Content of Process & Technology in our journal

Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Effect of particle size on thermal decomposition kinetics of micron magnesium hydroxide Yingchun CHEN Hang CHEN Jianguo YU The Chinese Journal of Process Engineering    2021, 21 (12): 1463-1472.   DOI: 10.12034/j.issn.1009-606X.220362 Abstract （223）      PDF （1746KB）（32）       Knowledge map    Save The non-isothermal pyrolysis kinetics of micron Mg(OH)2 is studied with the thermogravimetric analyzer under nitrogen atmosphere. It mainly focuses on clarifying the effects of particle size on the pyrolysis process. The measured thermogravimetric curves show a stepwise characteristic. At the main decomposition stage, the pyrolysis of Mg(OH)2 is rapid with a sudden mass loss. At the subsequent stage where conversion rate is larger than 0.8, the rate of weight loss decreases significantly because the diffusion of product water vapor is hindered by the product of MgO film. As for the main decomposition stage with conversion rate of 0~0.8, the Starink method and combined kinetic analysis are applied to fit and analyze its kinetic model. It is found that particle size has no distinct effect on the pyrolysis kinetics of micron Mg(OH)2. The model fitting results show that the pyrolysis reaction activation energy of micron Mg(OH)2 is 129.4 kJ/mol, the pre exponential factor is 1.820×1010 min?1, the pyrolysis reaction process follows the mechanism of random nucleation and growth of nuclei (A1.5). Compared to the experimental results, the thermogravimetric curves reconstructed based on these fitting parameter have the deviation less than 5%, which indicates that the kinetic model is reasonable. Meanwhile, it can be concluded that the pyrolysis process is controlled by decomposition reaction in the investigated range with the conversion rate from 0 to 0.8. The resistance effect of particle heat conduction and product water vapor diffusion is weak relatively. The main process of Mg(OH)2 weight loss is approximate to a homogeneous reaction. Considering the current investigation mainly focuses on the main decomposition stage of Mg(OH)2 with the conversion rate from 0 to 0.8, the kinetics of second stage of weight loss process remains to be studied further. Related Articles | Metrics Select Investigation on direct to blister copper smelting for high?grade copper concentrate Shiwei ZHOU Xiang GUO Kelun ZHANG Ba ZHANG Bo LI Yonggang WEI The Chinese Journal of Process Engineering    2021, 21 (12): 1473-1480.   DOI: 10.12034/j.issn.1009-606X.220421 Abstract （378）      PDF （1423KB）（43）       Knowledge map    Save Conventional copper smelting technology combines two steps of smelting and converting, with oxygen-enriched smelting as a typical representative. Intermittent operations would inevitably cause common issues such as long operation procedures and low-level sulfur dioxide pollution. Therefore, development of short-process for copper smelting technology is particularly necessary. Direct to blister copper smelting technology was carried out in a single furnace. It has the advantages of short process, good environmental benefits, and low investment cost, which is in line with the development direction of modern short-process smelting technology. The high-grade copper concentrate was used as raw ore for direct to blister copper smelting in present, and the method of theoretical calculations combined with experiments in lab-scale was adopted to investigate the phase transformation, blister copper yield, and copper content in the slag during the smelting process. Theoretical calculations indicated that the spinel phase in the melt can be avoided by adding CaO, as the ratio of iron to silicon was controlled to be 0.6 in the raw material. The corresponding chemically dissolved copper content in the slag at 1300℃ was approximately 8.6wt%. The effects of the amount of injected oxygen and settling time on the weight of blister copper and slag properties was discussed. For 80 g raw material, the oxygen-enriched air (50vol% O2) with a rate of 0.4 L/min was injected for 70 min, and then settling for 2 h. The experimental results indicated that the blister copper with a recovery rate of 82.12% could be obtained from a high-grade copper concentrate containing 45.94% Cu via direct to blister copper smelting at 1300℃. SEM-EDS analysis method was used to investigate the microstructure of the slag, which indicated that a large amount of spinel phase existed in the slag, hindering the sedimentation of copper particle. The copper in the form of mechanical entrainment was observed as a result. Related Articles | Metrics Select Effect of external magnetic field on cleanliness of electroslag ingot Xiaofang SHI Chunli ZHU Tao XU Lizhong CHANG The Chinese Journal of Process Engineering    2021, 21 (12): 1481-1490.   DOI: 10.12034/j.issn.1009-606X.221010 Abstract （214）      PDF （1034KB）（40）       Knowledge map    Save In order to further remove the large inclusions, an electroslag remelting furnace with electromagnetic stirring is designed and the effects of external magnetic field and different electrical parameters on the cleanliness of electroslag ingot are studied. The gas content is analyzed by oxygen and nitrogen analyzer, and the morphology, composition and size of inclusions are observed and analyzed by scanning electron microscope. It is found that the oxygen content in ESR ingot increases obviously after electroslag remelting whether the external magnetic field is applied or not, but the nitrogen content decreased slightly. The oxygen content in consumable electrode increased from 0.0007% to 0.0052%, and the growth rate is as high as 7 times. However, the types of inclusions are basically unchanged, which are mainly composed of alumina, manganese sulfide, manganese sulfide oxide composite inclusions and oxides, among which alumina is the most. After remelting with external magnetic field, the diameter of the largest inclusion in the consumable electrode decreased from 89.6 μm to 12.1 μm in ESR ingot (1.1 kA/108 Gs), the proportion of small inclusions increases and the number of large inclusions decreases. However, excessive electromagnetic force is not conducive to the removal of large inclusions. When the remelting current is 1.5 kA and the magnetic induction is 108 Gs, the electromagnetic force is the largest, and the maximum diameter of inclusions is up to 30.6 μm which is larger than that in electroslag ingot without magnetic field. The increase of oxygen content after electroslag remelting is caused by air pollution and unstable oxides in slag. The electromagnetic force generated by external magnetic field increases the contact area between slag and metal, thus absorbing large inclusion. Related Articles | Metrics Select Comparative study on typical vertical flame spread characteristics of EPS insulation material under concave structure Xinjie HUANG Jinda GAO Zhijie ZHOU Xiaofeng ZHANG Junjie HU The Chinese Journal of Process Engineering    2021, 21 (11): 1315-1322.   DOI: 10.12034/j.issn.1009-606X.220315 Abstract （247）      PDF （2621KB）（97）       Knowledge map    Save The vertical upward and downward flame spread characteristics of insulation material EPS in the concave structure were studied by building a small-scale flame spread experimental platform. The changes of parameters such as flame structure characteristics, flame spread speed, mass loss rate, flame temperature were comparatively analyzed. The research results showed that in the process of vertical upward spreading, EPS appeared stagnant combustion; this was mainly caused by the large gas flow generated by the chimney effect. However, in the process of vertical downward spreading, the flame spread speed was obviously accelerated due to the increase of EPS accumulated in the process of flame spread and the effect of the reverse stack effect. During the upward spreading process, the length of the pyrolysis zone was significantly longer than the pyrolysis zone spreading downwards. At the same time, the flame was basically inclined to both sides of the concave groove, and the molten dripping of the material can be clearly seen, but it was spreading downwards almost no molten spilled liquid. The mass loss rate in the process of flame spread was affected by the flame height to a great extent, which was mainly manifested in two stages: initial oscillation stage and stable oscillation stage. The influence of the stack effect on it was transient and temporary. In the unburned area, the flame temperature experienced two temperature peaks, and the first peak was larger than the second peak in the case of upward spread; while the first peak was smaller than the second peak for downward propagation. This was mainly due to the structure of the flame and the directional characteristics of the chimney effect, resulting in the generation of two different peak sizes. The research results of this work can provide early theoretical and reference value for the study of flame spread characteristics under actual concave structures. Related Articles | Metrics Select Effect of coordination of acoustic wave and chemical agglomeration on fine dust agglomeration in converter Yuqing ZHANG Yimin YIN Haiying LI Qiudong HU The Chinese Journal of Process Engineering    2021, 21 (11): 1323-1329.   DOI: 10.12034/j.issn.1009-606X.220343 Abstract （302）      PDF （978KB）（103）       Knowledge map    Save At present, air pollution caused by heavy industrial products such as iron and steel, thermal power generation and cement is still very serious in China. The main reason is the low dust removal effect of PM2.5 and PM10 particles. To solve the problem of difficult treatment of fine dust in converter flue gas, the collaborative treatment method based on acoustic waves and chemical agglomeration was used to pretreat converter flue gas dust in an evaporative cooler to improve the dust removal efficiency of fine dust. Single-factor experiment and orthogonal experiment were used to study the agglomeration effect of fine dust under different factors, such as the type of flocculants [acrylamide (PAM), sodium carboxymethyl cellulose (CMC) and xanthan gum (XTG)], flocculant concentration, acoustic frequency and acoustic field time. The results of the single-factor experiment showed that the agglomeration effect of the three flocculants was PAM>CMC>XTG from large to small, taking the increase of the peak particle size of the fine dust as the evaluation standard. The agglomerating effect was the best when the concentration of agglomerating agent was 0.1 g/L, the effect was obvious when the acoustic frequency was 33 kHz, and the effect was the best when the acoustic residence time was 15 s. The synergistic effect of the acoustic wave and chemical agglomeration was better than that of chemical agglomeration and acoustic wave alone. The results of the orthogonal experiment showed that when the concentration was 0.1 g/L, the acoustic frequency was 33 kHz, and the acoustic residence time was 15 s, the agglomeration effect was the most significant. The peak particle size increased from 3.311 μm to 43.59 μm, and the dust removal efficiency of the corresponding electrostatic precipitator reached 97%. From the experimental comparison of the coordination mechanism and the single agglomeration mechanism, the synergetic mechanism combined the advantages of a single agglomeration mechanism such as chemistry and acoustic waves, and provided a feasible basis for multi-mechanism dust removal in the industry. The results can provide reliable basic data for improving the removal of fine dust in the flue gas of iron and steel production, and lay a foundation for improving the removal efficiency of fine dust in the industrial flue gas. Related Articles | Metrics Select Study on wettability difference of profiled fiber based on optical measurement Feng CHEN Yuchen HU Jinjie LU Xiaolin WU Zhongli JI The Chinese Journal of Process Engineering    2021, 21 (11): 1330-1337.   DOI: 10.12034/j.issn.1009-606X.221226 Abstract （279）      PDF （2070KB）（113）       Knowledge map    Save Gas-liquid coalescence filtration is widely used in process industry. The wettability of fiber material is the key factor affecting the filtration performance of coalescing element. Based on the optical measurement method, the wettability difference of liquid on the surface of single triangular, trilobal and cruciform fiber was studied. The change process of liquid contact angle and volume was analyzed, and the influence of liquid type, fiber inclination angle and profiled degree on wettability was investigated. The results showed that with the decrease of liquid surface tension, the contact angle reduced and therefore the wettability enhanced. However, the volatility of liquid was easy to cause the actual contact angle to be greater than the theoretical one. The contact angle of triethylene glycol, dioctyl sebacate and silicone oil did not change with time. The contact angle of water and ethanol gradually decreased with time, and the decreasing rate of ethanol was greater due to the higher evaporation rate. The contact angle of liquid presented a "V" shape distribution with the inclination angle of the profiled fiber, that was, there was a minimum point (inclination angle of 30°) to make the fiber wettability reach the best. When the profiled degree of the fiber increased, the contact angle difference between different liquid decreased and the overall wettability improved, which indicated that the fiber with higher profiled degree should be selected as the material of prefilter layer or drainage layer. Related Articles | Metrics Select Dilution of Isa copper smelting slag by carbothermic reduction with waste cathode carbon Guodong WU Lei LI Kongzhai LI Yong YU The Chinese Journal of Process Engineering    2021, 21 (10): 1187-1195.   DOI: 10.12034/j.issn.1009-606X.220327 Abstract （248）      PDF （1967KB）（146）       Knowledge map    Save Massive waste cathode carbon block are produced from the electrolytic aluminum process each year, which is mainly composed of carbon, sodium fluoride and other compounds. The fluoride and cyanide components in it cause serious environment pollution if it accumulated and exposed to air for a long time. It is regarded as a hazardous waste by various environmental bodies. An innovative method for resource processing of this waste cathode carbon block was proposed in this work. Using this waste cathode carbon block as the reducing agent can realize the effective dilution and recovery of copper from the smelting slag of Isa copper through a reduction process. According to thermodynamic analysis, the influence of the amount of waste cathode carbon addition, reduction temperature, holding time and CaO addition on the recovery ratio of copper dilution in Isa copper smelting slag was studied. The results showed that the recovery ratio of copper dilution can reach 98.24% under the conditions of waste cathode carbon addition amount of 2.0%, reduction temperature of 1300℃ and holding time of 60 min. At the same time, the F in the waste cathode carbon can be transferred and fixed in the diluted tailings in the form of CaF2. The toxic leaching concentrations of F? and CN? in the tailings were far lower than the national permissible emission standard. The research has realized the high-efficiency recovery of copper from Isa copper smelting slag and the resource utilization of waste cathode carbon. Related Articles | Metrics Select Structure design and optimization of thin plate static mixer for dilution water mixing Jianqiu LU Jiaqing CHEN Wenjin LIU Quan LUO Guodong DING Xiaoping WANG The Chinese Journal of Process Engineering    2021, 21 (10): 1196-1206.   DOI: 10.12034/j.issn.1009-606X.220322 Abstract （337）      PDF （2902KB）（169）       Knowledge map    Save The dilution water blending is a key link in the crude oil electrical desalination system of oil fields or refineries, which directly affects the efficiency and operating energy consumption of electrical desalination. In order to further simplify the equipment structure, reduce costs and increase system efficiency, a thin plate static mixer for dilution water mixing was proposed. On the basis of the preliminary structural design of the thin plate static mixer, computational fluid dynamics (CFD) was used to perform three-dimensional numerical simulation of oil-water mixing, the square root of segregation strength (IOS0.5) in a uniform mixing state and pipeline pressure drop (Δp) were used as evaluation parameter, which can indicate the influence of structural parameters on the uniformity of oil-water mixing and the running energy. The structural parameters were the length of water injection pipe, the distance between water injection pipe and thin plate, thin plate guide position and the thickness of bending sheet. Subsequently, with the inner diameter D of the hybrid pipeline as a reference, the key structural parameters were optimized by the response surface method (RSM), and the mixing performance under the optimal combination of structural parameters was predicted. The optimal combination of structural parameters obtained by optimization was as follow: the length of the injection pipe was 1/3D, the distance between the center of the injection pipe and the orifice was 4/25D, the guiding position of the orifice was 1/8π, and the thickness of the orifice was 1/25D. By comparing and analyzing the mixing effect of the thin plate static mixer before and after optimization, it was found that the optimized structure of IOS0.5 was 43.06%, which was lower than before optimization. Qualitative analysis of the water phase velocity cloud diagram and streamline diagram in the thin plate mixer showed that when the water injection ratio was 2%, the oil and water two phases can reach a uniform mixing state at the 3D downstream of the water injection pipe. It can be seen that the thin plate static mixer can quickly achieve uniform mixing of oil and water at a small water injection ratio. Related Articles | Metrics Select Leaching of valuable metals from nickel sulfide ores by mechanical activation Xiaohong ZHENG Weiguang LÜ Hongbin CAO Nan CAI Jin ZHAN Qingchun LI Fei KANG Zhi SUN The Chinese Journal of Process Engineering    2021, 21 (9): 1064-1073.   DOI: 10.12034/j.issn.1009-606X.220146 Abstract （244）      PDF （3050KB）（231）       Knowledge map    Save The demand for nickel resources has increased significantly in recent years due to the large-scale application of high-nickel ternary lithium batteries in the field of new energy electric vehicles. To alleviate the shortage of nickel resources in China, the nickel extraction from nickel-containing minerals has received widely attention. As an important nickel-containing minerals, the composition of nickel sulfide ore is complex and it is difficult to be leaching under atmospheric conditions. Therefore, green, high efficient, and low-cost technologies for extracting nickel from nickel sulfide ore resources have attracted much attention. In this work, the mechanical activation was introduced to increase the reactivity of nickel sulfide ore, then Na2S2O8 was used to leaching activated nickel sulfide ore under atmospheric conditions. Various conditions including rotation speed, ball-to-material ratio and ball milling time as well as the acid concentration, oxidation concentration, leaching time, liquid-to-solid ratio, stirring rate and temperature in the leaching process were optimized and the mechanism was further discussed. It was found that the mechanical activation process reduced the particle size and increased the degree of amorphization of nickel sulfide ore resulting in an increase in its reactivity, and the leaching process converted part of the S2- to sulfur by Na2S2O8 reducing the release of harmful gas H2S during the reaction. At the optimal conditions (rotation speed of 613 r/min, ball-to-material ratio of 20:1, ball milling time of 120 min, acid concentration of 2 mol/L, Na2S2O8 concentration of 0.42 mol/L, leaching time of 60 min, liquid-to-solid ratio of 5:1, stirring rate of 400 r/min and temperature of 80℃), leaching rate of Ni, Co, Cu and Fe were 98.9%, 97.7%, 98.2% and 98.7%, respectively, while the content of Ni, Co and Cu in residues were 0.45%, 0.03% and 0.14%, respectively. With this research, it was expected to provide theoretical and technical support for the efficient extraction of valuable metals from nickel sulfide ores. Related Articles | Metrics Select Characteristics of silicon-based substances effect on hot-metal dephosphorization process Guobin SUN Xiaodong XIANG The Chinese Journal of Process Engineering    2021, 21 (8): 944-950.   DOI: 10.12034/j.issn.1009-606X.220183 Abstract （353）   HTML （3）    PDF （663KB）（109）       Knowledge map    Save In the context of increasing domestic demand for hot-metal dephosphorization and advocating the utilization of solid waste, it is of great practical value to understand the effect of silicon impurities on the hot-metal dephosphorization when industrial solid waste is used to prepare dephosphorizer. Therefore, in order to explore the effect of silicon-based substances on dephosphorization efficiency, the dephosphorization experiments were carried out by using ferrosilicon and SiO2 to prepare hot-metals containing different mass fraction of silicon and dephosphorizers containing different mass fraction of SiO2. Meanwhile, to further understand the characteristics of hot-metal dephosphorization when different silicon-based substances were used as initial conditions in the slag-iron system, under the condition of ensuring the same molar amount of silicon-based substances, the dephosphorization experiments were carried out by selecting different silicon-based substances involved in desiliconization process as an additive to hot-metal or dephosphorizer, including ferrosilicon, SiO2 and CaSiO3, and the overall mass transfer coefficient of phosphorus in the three experiments was calculated by theoretical derivation and curve fitting. The results had shown that under the conditions of temperature 1400℃ and initial hot-metal phosphorus content of 0.3wt%, when the initial hot-metal silicon content was 0.4wt%, the highest dephosphorization efficiency can be obtained. The effect of initial SiO2 content in the dephosphorizer on dephosphorization efficiency can be ignored. In addition, under the condition that the molar amounts of silicon, SiO2 and CaSiO3 were the same, a higher overall mass transfer coefficient of phosphorus can be obtained in the hot-metal dephosphorization by using the dephosphorizer containing CaSiO3. Related Articles | Metrics Select Impurity removal and hydrothermal heterogeneous cryogenic rapid oxidation of semi-dry desulfurization ash from iron ore sintering flue gas Rufei WEI Yulong ZHU Di ZHOU Yifan WANG Hongming LONG The Chinese Journal of Process Engineering    2021, 21 (8): 951-958.   DOI: 10.12034/j.issn.1009-606X.220223 Abstract （369）   HTML （11）    PDF （1803KB）（269）       Knowledge map    Save The semi-dry desulfurization ash of iron ore sintering flue gas cannot be effectively utilized because it contains a lot of unstable calcium sulfite. Oxidation modification of desulfurization ash is an important means to realize its large-scale or high-value utilization. The results show that the calcium carbonate in the desulfurization ash is the main factor limiting its oxidation modification. Calcium carbonate and calcium sulfite cover each other, which reduces the specific surface area of calcium sulfite oxidation reaction and limits its oxidation rate. Two weak acids, L(+)-ascorbic acid and glacial acetic acid, were used to remove calcium carbonate. Glacial acetic acid with a concentration of 0.4 g/g could increase the content of calcium sulfite to 81.17% with the maximum increase of 69.71%. The effect of different factors on the oxidation rate of calcium sulfite in desulfurization ash was studied by subcritical hydrothermal heterogeneous oxidation method. The results showed that the oxidation rate of calcium sulfite was significantly increased after removing impurities. The oxidation rate of calcium sulfite can be increased by increasing the initial pressure, the reaction temperature and time, and reducing the solid-liquid ratio. When the reaction temperature was 140℃, the reaction time was 30 min, the initial pressure was 2 MPa, the initial solid-liquid ratio was 1:30 and the rotating speed was 300 r/min, the oxidation rate of calcium sulfite was 98.72%, while the oxidation rate of desulfurized ash without impurity removal was only 78.77% at 180℃(other conditions were the same). In this work, the desulfurization ash was oxidized rapidly at low temperature. From the micro morphology point of view, compared with the desulfurized ash without impurity removal, the calcium sulfite after impurity removal was easier to grow along the radial direction, which had preliminary conditions for the preparation of calcium sulfate whiskers with a large aspect ratio, which was of great significance for the preparation of calcium sulfate whiskers. Related Articles | Metrics Select Influence of the dilution gas flow rate on SiO 2 deposition on the powder surface during the fluidized vapor deposition Zhaoyang WU Zihan GAO Hui KONG Chen XIAN Jixiang JIA Xiangwei LIAO The Chinese Journal of Process Engineering    2021, 21 (8): 959-968.   DOI: 10.12034/j.issn.1009-606X.220257 Abstract （257）   HTML （3）    PDF （4268KB）（136）       Knowledge map    Save Using Fe(Si) alloy particles as deposition basement materials and tetraethoxysilane as gas SiO2 precursor, Fe(Si)/SiO2 composite powders were synthesized under fluidized vapor deposition. The influence of Ar dilution gas flow rate on deposition process of SiO2 insulating medium, and the formation Ar dilution gas flow rate range of complete Fe(Si)/SiO2 core-shell heterostructure were investigated. The results showed that the microstructure of SiO2 insulating medium on the Fe(Si) particle base surface varied from submicron clusters to integrated films to porous films with the increasing of Ar dilution gas flow rate during a fluidized vapor deposition process, while the deposition rates SiO2 insulating medium first decreased, then increased and decreased again. The homogeneity of the SiO2 insulating medium was the best and the deposition rate was 0.069 nm/s when the Ar dilution gas was at a flow rate of 250 sccm. In addition, when reaction temperature, reaction time, gas SiO2 precursor content and carrier gas flow rate was 930 K, 60 min, 9 mL and 100 sccm respectively, the conversion from Fe(Si) alloy particles to complete Fe(Si)/SiO2 core-shell heterostructure particles during the fluidized vapor deposition occurred within the Ar dilution gas flow rate range from 200 sccm to 300 sccm. The results of the performance test indicated that the Fe(Si)/SiO2 core-shell heterostructure led to a substantial enhancement in the electrical resistivity of the particles and reduction in their saturation magnetization, but hardly affected the coercive force. Compare to Fe(Si) alloy particles, the Fe(Si)/SiO2 core-shell heterostructure particles exhibited much higher electrical resistivity. The varying trend of Fe(Si)/SiO2 core-shell heterostructure particles was consistent with the deposition rate of SiO2 insulating medium. The results in this study may provide a foundation for future kinetics investigations and the application of fluidized vapor deposition technology. Related Articles | Metrics Select Study on uniaxial/triaxial impact dynamic properties of structurally heterogeneous coal Weimin LIANG, Heng LIU, Minmin LI, Gaowei YUE The Chinese Journal of Process Engineering    2021, 21 (7): 817-826.   DOI: 10.12034/j.issn.1009-606X.220178 Abstract （235）   HTML （2）    PDF （2763KB）（84）       Knowledge map    Save As a heterogeneous, anisotropic and porous porous brittle material, the coal body has a large number of micro-scales such as bedding, joints, cracks, etc. so that the blasting and cracking effects in different directions will be significantly different. Based on this, a split Hopkinson pressure bar (SHPB) experimental device was used to perform impact loads of 0.1, 0.15, 0.2, 0.3, 0.5 MPa on the coal samples taken from the vertical and parallel bedding directions. The uniaxial/triaxial SHPB impact test was used to compare the uniaxial/triaxial impact dynamics performance of the anisotropic coal body stress-strain, peak stress, average strain rate, etc. after the impact. The results showed that under the action, the uniaxial and triaxial stress-strain curves had the same trend, and the peak stress and average strain rate increased with the impact load, and the growth trend was also the same. When the uniaxial impact, the stress of the coal sample followed the strain which can reach the peak stress quickly and dropped down quickly to complete the unloading. During triaxial impact, this stage was relatively smooth and had a longer elastoplastic deformation, so its dynamic mechanical properties were also improved well. Due to the relatively weak bonding surface between coal layers, the dynamic compressive strength was relatively smaller than the dynamic compressive strength in the vertical bedding direction; the triaxial SHPB impact had the peak stress and average strain rate under the constraint of the axial and confining pressures on the coal sample compared to the uniaxial improved, and the peak stress increased the most when the impact load was 0.15~0.2 MPa, increasing by about 50%. The dynamic performance improvement in the vertical bedding direction was slightly better than that in the parallel bedding direction. The effect of pressure had certain limitations, that was a certain confining pressure had a certain limit to improve the mechanical properties of coal samples. Table and Figures | Reference | Related Articles | Metrics Select Effect of V content on microstructure and mechanical properties of Ti-V complex microalloyed steel Zihao CHEN, Ke ZHANG, Xibin FU, Zhaodong LI, Xi ZHANG, Xiaofeng ZHANG, Xinjun SUN, Jianqing QIAN The Chinese Journal of Process Engineering    2021, 21 (7): 827-835.   DOI: 10.12034/j.issn.1009-606X.221107 Abstract （302）   HTML （2）    PDF （1505KB）（103）       Knowledge map    Save Using the combination of microalloying technology and controlled rolling and controlled cooling technology, the development of microalloyed high-strength steels with well-matched strength and toughness and low cost has gradually become a research hotspot, which mainly improve the properties of microalloyed steel by the soft toughness of ferrite and the precipitation strengthening of nano microalloyed carbonitride. At present, there are few reports about the effect of V content on the strength and plasticity of hot-rolled Ti-V complex microalloyed steel sheet at domestic and abroad. Therefore, the research on the microstructure and mechanical properties of hot-rolled Ti-V complex microalloyed steel sheet can provide theoretical basis and process guidance for the development and microstructure and properties control of Ti-V complex microalloyed high strength steel. Two kinds of Ti-V complex microalloyed steels with different V contents were obtained by adding Ti and V microalloying elements. Meanwhile, the effect of V content on the microstructure and mechanical properties of Ti-V microalloyed steels at different coiling temperatures were discussed by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD) and physicochemical phase analysis. The results showed that when the two Ti-V microalloyed steels were coiled at 500~650℃, the microstructure was composed of polygonal ferrite and pearlite, and the formation of pearlite was inhibited by increasing the V content. When coiled at 500~650℃, with the increase of V content, the uniform elongation and total elongation decreased to a certain extent, while the tensile strength and yield strength increased significantly. The coiling temperature had little effect on the uniform elongation and total elongation and the comprehensive mechanical properties of the two experimental steels were up to best when coiled at 600℃. With the increase of V content significantly increased the number of (Ti, V)C particles smaller than 10 nm in size when coiled at 600℃. The precipitation strengthening increment σP of high vanadium steel was about 183 MPa, and the strengthening mechanisms were mainly precipitation strengthening and fine grain strengthening. V content was the main factor affecting precipitation strengthening increment and yield strength of Ti-V complex microalloyed steel. Table and Figures | Reference | Related Articles | Metrics Select First-principles calculation of adsorption mechanism of hydrochloric acid on chalcopyrite surface Xiaoliang LI, Guocai TIAN The Chinese Journal of Process Engineering    2021, 21 (7): 836-846.   DOI: 10.12034/j.issn.1009-606X.220175 Abstract （502）   HTML （2）    PDF （1478KB）（151）       Knowledge map    Save The leaching of chalcopyrite has always been the core of copper sulfide hydrometallurgy, but chalcopyrite is a sulfide mineral that is difficult to be oxidized and decomposed. At present, a large number of macroscopic phenomena are obtained by focusing on experimental research, and the mechanism is mostly inferred. However, the lack of information on atomic or molecular level hinders the clear and effective explanation to these macroscopic phenomena. Therefore, it is necessary to study the surface interaction between liquid medium and chalcopyrite and the influence of medium on the formation of surface products by means of atomic or molecular level calculation and analysis, which are of great significance to reveal the reaction mechanism of leaching process and improve or develop a green hydrometallurgical technology of chalcopyrite. As a common leaching agent, hydrochloric acid can be used in the leaching of chalcopyrite, and it has been widely studied because of its advantages of recyclable leaching agent, high solubility of metal ions, good oxidation reduction performance and fast leaching rate. In this work, the adsorption and reaction mechanism of hydrochloric acid on different sites of chalcopyrite surface were studied with first-principles calculation. It was shown that the reconstructed sulfur terminated chalcopyrite (001) surface [labeled as (001)-S surface] led to the formation of disulphide S22-. Hydrochloric acid was adsorbed on the sulfur terminated surface (001)-S of chalcopyrite in the form of dissociation. In the process of leaching, the adsorption of H+ on sulfur terminated surface (001)-S of chalcopyrite destroyed the S22- formed on the surface. The surface structure of chalcopyrite (001)-S was destroyed by adsorption of chloride ion Cl-. During the adsorption process, the chemical reactions between H+ and Cl- with the surface of chalcopyrite produce the FeCl2 and H2S, which were both beneficial to the leaching of chalcopyrite. The results can provide a theoretical basis and guidance for future research. Table and Figures | Reference | Related Articles | Metrics Select Green synthesis of m-xylylene dicarbamate using urea as carbonylation reagent Xiaoyu HUANG Junya CAO Fenggang HAN Liguo WANG Yan CAO Peng HE Shuang XU Jiaqiang CHEN Fan YI Huiquan LI The Chinese Journal of Process Engineering    2021, 21 (5): 587-593.   DOI: 10.12034/j.issn.1009-606X.220087 Abstract （284）      PDF （737KB）（159）       Knowledge map    Save M-xylylene diisocyanate (XDI) is an important special isocyanate that draws more and more attention in recent years. The introduction of the –CH2– group between the benzene ring and isocyanate group, which makes it resistant to yellowing, can be applied in the fields of high value-added polyurethanes, such as high-grade coatings, medical polyurethane, high-grade optical polyurethane, and so on. M-xylylene dicarbamate (XDC) is the key intermediate for the synthesis of XDI via the non-phosgene thermal decomposition route. In this work, a novel methodology for the synthesis of XDC via carbonylation of m-xylylenediamine (XDA) using urea as carbonylation reagent over TiO2 catalyst was proposed. The standard XDC sample was first synthesized by the reverse reaction between XDI and ethanol, and then, the qualitative analysis of the standard XDC sample was characterized by FT-IR and 1H-NMR to confirm its structure. The standard curve of XDC was then successfully established in liquid chromatography with a correlation coefficient of more than 0.999. The qualitative analysis of the target product was carried out by GC-MS, and the reaction path was primarily speculated. Furthermore, the effects of different catalysts, reaction temperature, reaction time, the molar ratio of raw materials, and catalyst dosage on the yield of XDC were studied. The results showed that using TiO2 as the catalyst, under the optimized conditions, the reaction temperature of 205℃, the reaction time of 6 h, n(urea):n(XDA) of 3:1, the amount of catalyst was 15wt% XDA, the conversion of XDA was 100%, and the yield of XDC could reach to as high as 82.4%. Therefore, this process not only provides a feasible route for green, effective, and economic production of XDC, but also provides a theoretical basis for the non-phosgene synthesis of special isocyanate XDI. Related Articles | Metrics Select Effect of water on microstructure and transport properties of ionic liquids Yandong GUO Linlin YOU Xiaochun ZHANG Chin. J. Process Eng.    2021, 21 (4): 431-439.   DOI: 10.12034/j.issn.1009-606X.220117 Abstract （413）      PDF （979KB）（134）       Knowledge map    Save Due to the unique structure and excellent physicochemical properties, ionic liquids have shown a broad application prospect. However, some water inevitably exists in ionic liquids during applications. The presence of waters has a significant impact on the structure and properties of ionic liquids. In this work, the microstructure, interactions and transport properties of [Bmim][B(CN)4], [Bmim][PF6] and [Bmim][Tf2N] with different contents of water were systematically studied by molecular dynamics simulations. By analyzing the number of hydrogen bonds for the system of ionic liquids and water, it was found that the number of hydrogen bonds between anions and water increased significantly with increasing water content, while the number of hydrogen bonds between anions and cation decreased gradually with the increase of water content. The number of hydrogen bonds between anions and water were greater than those between cations and water. The self-diffusion coefficients for the mixture of ionic liquids and water were calculated. It was found that the self-diffusion coefficient of the ionic liquid increased gradually with the increase of the water content. The more hydrophilic the ionic liquids were, the more the diffusion coefficient increased. The radial distribution function and coordination number results showed that the interaction between anions and water was stronger than that between cations and water. However, addition of water to ionic liquids was found to have no impact on the structure between anions and cations. In addition, the results of the spatial distribution function suggested that the distribution of anions and water around H5 and H4 of imidazolium cation ring were competitive, which reduced the interaction between cations and anions. This research results can help to further understand the microscopic mechanism of ionic liquids and water system and promote the application of ionic liquids. Related Articles | Metrics Select Reduction of magnesium oxide in calcined dolomite with a mixture of aluminum and ferrosilicon Yaoning WANG Hongzhou MA Zhixian WANG Dingding WANG Bixia WANG Chin. J. Process Eng.    2021, 21 (4): 440-445.   DOI: 10.12034/j.issn.1009-606X.220138 Abstract （563）      PDF （475KB）（121）       Knowledge map    Save The Pidgeon process is the main process of magnesium production. The higher reduction temperature of the silicothermic process results in high energy consumption in the magnesium reduction process. Improving the reducing performance of reducing agents was one of the ways to reduce the energy consumption of metallic magnesium production. The theoretical and experimental research on the reduction of MgO in calcined dolomite was studied by the mixture of aluminum and ferrosilicon as reducing agents. The effects of aluminum dosage, reduction time and temperature on the reduction rate of magnesium were discussed. The reduction process of magnesium oxide and the phase transformation of aluminum and ferrosilicon at different temperatures were studied. The results showed that when aluminum was involved in the reduction of magnesium oxide by silicothermic method, the initial reaction temperature of reduction of MgO by silicothermic method was reduced to below 700℃, and the effect of improving the reduction rate of MgO was obvious in the low-temperature stage. The reduction process of magnesium oxide by aluminum included two aspects. On the one hand, it was directly involved in the reduction of magnesium oxide to MgO?Al2O3. With the increase of temperature, MgO?Al2O3 was further reduced by aluminum. On the other hand, aluminum and ferrosilicon from the Al3FeSi2 phase, which promoted the reduction of silicon and reduced the temperature of silicon participating in the reduction of magnesium oxide. In the presence of aluminum, the reduction process of magnesium oxide by ferrosilicon was as follows: at 700~950℃, silicon participated in a reduction in the form of Al3FeSi2, and at 1200℃, the magnesium oxide was reduced in the form of Si and FeSi2. Under the experimental conditions, when aluminum participated in the reduction of magnesium by ferrosilicon, the reduction rate of magnesium oxide increased gradually with the increase of aluminum dosage. When the aluminum dosage was 12% and 1000℃, the reduction rate of magnesium oxide can reach more than 90%. Aluminum participated in the reduction of MgO to produce alumina, which reactd with CaO and SiO2 in calcined dolomite to produce CaAl2O4, CaAl2Si2O8. Related Articles | Metrics Select Role of surface energy in the formation of ice morphology Qinqin WU Yongjun CHEN Xianglei DONG Hui XING Yongsheng HAN Chin. J. Process Eng.    2021, 21 (4): 446-453.   DOI: 10.12034/j.issn.1009-606X.220110 Abstract （424）      PDF （3844KB）（239）       Knowledge map    Save The icing phenomenon is ubiquitous in nature, from the formation of snowflakes to the low-temperature preservation of food to the anti-icing of aircraft wings. It is both a scientific and technological interest to understand and control the morphology of ice crystals. Inspired by the concept of mesoscience, this study raises the scientific hypothesis that surface energy plays an important role in the morphology evolution of ice crystals. To regulate the surface energy, different additives (sucrose, sodium chloride, and surfactant SDS) were added to the aqueous solution, and the icing processes with different surface tensions was observed by a homemade cooling device loaded at a laser confocal microscope. It was found that the morphologies of ice crystals transfer from dendritic with good symmetry to disordered seaweed crystals with the decrease of the surface tension at the same undercooling conditions, and this change was verified in different kinds of solutions. Further investigations showed that the lower surface tension of the solution resulted in a change of growth rate of ices in the solution. At high growth rates, the growing surface of ice crystals became unstable, and the crystal plane grew anisotropically, resulting in the formation of dendrite structures. However, at low growth rates, the growth surface of ice crystals was covered by additive molecules. The anisotropy of the crystal plane disappears, and hence a disordered dendrite structure was formed. The above findings confirmed the dominant role of supercooling and surface energy in the growth of the material structure, which provides experimental proof to evaluate the concept of mesoscience. Related Articles | Metrics Select Effect of high-pressure water jet on monomer dissociation degree in Bayan Obo Mine Yibo GAO Chunhua BAI Jianying WANG Xu WU Xiao LEI Chin. J. Process Eng.    2021, 21 (3): 298-304.   DOI: 10.12034/j.issn.1009-606X.220014 Abstract （394）      PDF （2010KB）（109）       Knowledge map    Save The dissociation of mineral monomers is one of the key factors that can be efficiently sorted. The crushing method has a great influence on the dissociation degree of mineral monomers. The Bayan Obo rare earth mine contains more than a dozen rare earth minerals, with the close symbiosis of minerals and complex embedded types. Among them, the rare earth is mainly concentrated in bastnaesite and monazite ore. The analysis shows that minerals form contiguous, network veins, dissolution and ring embedment due to mutual enveloping, interpenetrating and alternation. To improve the dissociation degree of mineral monomers, the water jet mineral dissociation device was independently developed to explore the influence of water jet velocity on the dissociation degree of rare earth monomers in Bayan Obo Mine. Under the same particle size distribution, the experimental results of high-pressure water jet pulverization and conventional ball milling (iron medium) were compared, and the effects of the two pulverization methods on the dissociation state of rare earth minerals and the particle interface were analyzed. The analysis by laser confocal microscope and the automatic quantitative analysis system of mineral characteristics (AMICS) showed that the dissociation degree of the high-pressure water jet crushing Bayan Obo rare earth mineral monomer was better than that of ball milling, and it had the characteristics of high dissociation degree and relatively uniform particle size, the natural interface of mineral particles keep better, the surface was smoother, the rare earth minerals were concentrated in the particles below 0.038 mm, which was beneficial to the flotation separation of rare earth, and had certain guiding significance for the ore crushing of the Bayan Obo mine. Related Articles | Metrics Select The construction of phase diagram for ionic liquid/wool fiber/coagulator ternary systems Fengjiao PAN Le ZHOU Shaojuan ZENG Xue LIU Yanrong LIU Yi NIE Chin. J. Process Eng.    2021, 21 (2): 160-166.   DOI: 10.12034/j.issn.1009-606X.220063 Abstract （372）      PDF （1252KB）（161）       Knowledge map    Save Keratin is one of the natural polymers with abundant reserves, wool fiber consists 95wt% of keratin, which is an important source of natural keratin and has excellent mechanical and biological properties. However, due to the numerous complex inter- and intra-molecular hydrogen bonds, disulfide bonds and other chemical bonds, wool fiber is insoluble in water and common organic solvents. As an emerging green solvent, ionic liquid (IL) shows outstanding performance in dissolving natural polymers such as wool fiber, cellulose, chitin, etc. due to their tunable structure, non-volatile, thermal stability, as well as high solubility for biopolymer. According to the reports, the current researches of ionic liquids on wool fiber are mainly focused on the solubility properties of wool fiber. The studies on the regeneration properties of wool keratin are still limited. There are three components involved in the regeneration process of wool fiber, and thus the thermodynamic behavior of polymer regeneration can be investigated by the ternary phase diagram. In this study, the linearized cloud point (LCP) correlation and ternary phase diagram of IL/wool fiber/coagulator (T) system were constructed by the turbidity method. The effects of coagulator types, coagulation temperatures, and structures of ILs on the properties of wool keratin regeneration were investigated systematically. The regenerated wool keratin was obtained using [Emim]Dep as the solvent with the coagulation temperature of 25℃. In different coagulator systems, the order of wool keratin regeneration capacity is water>ethanol>iso-propanol. The regenerated wool keratin was obtained using [Emim]Dep as the solvent, and water as the coagulator. In different coagulation temperature systems, as the coagulation temperature increased, the regeneration capacity of wool keratin gradually decreased. The regenerated wool keratin was obtained using water as the coagulator with a coagulation temperature of 25℃. In different IL structure systems, the order of wool keratin regeneration capacity was [Emim]Dep>[DBNE]Dep>[DBNH]OAc. The characterization of raw wool fiber and regenerated wool keratin under different regeneration conditions were obtained by FT-IR and XRD, the characterization of the structures and properties showed that the main structure of the regenerated wool keratin basically agreed with the raw wool fiber, and the crystallinity of the regenerated wool keratin had decreased than raw wool keratin. The highest crystallinity of the regenerated wool keratin was obtained from the system of [Emim]Dep/wool fiber/water system at the coagulation temperature of 25℃. Related Articles | Metrics Select Release of sulfur from roasting the acid leaching tailings of vanadium-bearing stone coal minerals as the raw materials for preparing ceramsite Chunguang SONG Hongling ZHANG Yuming DONG Lili PEI Honghui LIU Junsheng JIANG Hongbin XU Chin. J. Process Eng.    2021, 21 (2): 167-173.   DOI: 10.12034/j.issn.1009-606X.220045 Abstract （382）      PDF （586KB）（133）       Knowledge map    Save The acid leaching tailings of vanadium-bearing stone coal minerals (hereinafter referred to as “tailings”) is the solid waste discharged in the industry of vanadium extraction from stone coal. Using the tailings as raw materials for the preparation of ceramsite is an important way for the resource ultilization of the tailings. Ceramsite can be widely used in many areas, and the main application is to be used as lightweight aggregate in construction industry. Lightweight aggregate has a critical requirement of sulfur content when it is used as building materials. The total contents of sulfate and sulfide, calculated by SO3, should be no higher than 1.0wt%. Usually, the sulfur content (calculated by SO3) of the tailings is much higher than 1.0wt%, which is much higher than the requirement of lightweight aggregate. So, it is necessary to study the release of sulfur during the preparation of ceramsite using tailings as raw materials. In this work, simultaneous thermogravimetric–Fourier transform infrared spectrometry (TG–FT-IR) analysis were used to investigate the weight loss, the exothermic/endothermic phenomenon, and releasing of gases in the process of roasting the tailings as the raw materials for preparing ceramsite. The sulfur contents of samples prepared by roasting tailings at different temperatures were tested, their crystal phases were characterized, the Gibbs free energies of several reactions were obtained by thermodynamic calculation, and the mechanism of sulfur releasing from tailings was discussed accordingly. The results showed that sulfur-containing substances in the tailings gradually decomposed and SO2 was released with temperature increasing. Consequently, the sulfur content of samples gradually decreased with roasting temperature increasing. The sulfur content (0.44wt%) of samples obtained at 1200℃ can meet the requirements of lightweight aggregate. Intermediated phases such as wollastonite (CaSiO3) might be formed by the reaction of anhydrite and quartz in the tailings, accompanied with the releasing of SO2. SiO2, Fe2O3 and Al2O3 in tailings might be helpful for the releasing of sulfur. Related Articles | Metrics Select The settling behavior of scaling ions in brine purification process by NaOH–flue gas method Xingguo LUO Jianbo PENG Sanqiang ZHENG Mingyu ZHANG Xingbin LI Chang WEI Zhigan DENG Chin. J. Process Eng.    2021, 21 (2): 174-182.   DOI: 10.12034/j.issn.1009-606X.220002 Abstract （385）      PDF （1105KB）（135）       Knowledge map    Save The scaling ions (Ca2+, Mg2+ and CO32–) in raw brine are easy to form calcium carbonate and calcium sulfate deposit in the process of vacuum evaporation. Because of their poor thermal conductivity and their good adherence to the walls, these mineral compounds decrease the heat transfer ratio and even shorten equipment life by corrosion. The brine purification method of NaOH–flue gas can utilize the flue gas from a power plant and low concentration waste alkali from chlor-alkali enterprises, which has absolute advantages and broad application prospects in energy conservation and environmental protection. In order to analyze the behavior of scaling ions in the process of brine purification by NaOH–flue gas method, the experiment of brine purification by CO2 instead of flue gas was carried out. The effects of CO2 feeding time and pH value on the behaviors of Ca2+, Mg2+ and CO32– in brine were investigated. The behavior of scaling ions and the mineralogical characteristics of precipitates were studied by thermodynamic calculation (Factsage), XRD and SEM–EDS. The thermodynamic and experimental results showed that when pH=11.5 and CO2 introduction time was 60 min, Ca2+ in raw brine was reduced to 6.0~8.0 mg/L, and Mg2+ concentration was reduced to 0.65 mg/L when the time was extended to 80 min. There was a linear relationship between the concentration of CO32– and CO2 entry time. Besides, the dissolution amount and ratio of CO2 in brine were the largest, and the equilibrium constant (K) was the largest at the pH=11.5. Then, the results of XRD and SEM showed that the precipitated vaterite type of calcium carbonate crystals was obtained when the pH of the process was controlled at 9.5. When the pH value increased to 10, the crystal form of calcium carbonate transformed from vaterite to aragonite crystals, and its morphology changed from a regular spherical shape to an oval shape. When the pH was 11 or 11.5, the precipitation was a eutectic of calcium and magnesium, and the crystal form of calcium carbonate was converted from vaterite to calcite crystals, which was more thermodynamically stable. Related Articles | Metrics Select Experiment and calculation for phase equilibria in quaternary system of ammonium dihydrogen phosphate-diammonium hydrogen phosphate-ammonium polyphosphate-water Xiaofu Lü Dehua XU Zhiye ZHANG Xinlong WANG Lin YANG Chin. J. Process Eng.    2021, 21 (1): 64-70.   DOI: 10.12034/j.issn.1009-606X.220042 Abstract （612）      PDF （497KB）（192）       Knowledge map    Save Ammonium polyphosphate is widely used in water soluble fertilizer industry due to its excellent water solubility, slow-release property and chelation. However, ammonium polyphosphate is easily hydrolyzed into ammonium dihydrogen phosphate and diammonium hydrogen phosphate in storage, and the composition of its aqueous solution changes continuously. Its solubility decreases with decreasing polymerization rate, causing crystallization and precipitation in the storage solution, that increases the cost of transportation and application. The quaternary phase diagram of ammonium dihydrogen phosphatediammonium hydrogen phosphateammonium polyphosphatewater at 25℃ was established by using Schreinemaker wet slag method, and the mass distribution of each component in saturated liquid and wet slag phase was obtained by ion chromatography and mass conservation equation. The reasons of crystallization and precipitation of ammonium polyphosphate solution were explained, which was a guidance for storage and use of ammonium polyphosphate as a high efficiency water-soluble fertilizer. The polymerization degree of ammonium polyphosphate was diverse due to the variety of ammonium polyphosphate products produced by the manufacturers. There were different solution systems while the ammonium polyphosphate as a compound fertilizer raw materials, and it was time-consuming and laborious to obtain phase diagrams by experiments for each system. The calculation of watersalt phase diagram by mathematical model can save a lot of experimental work and provide the basis for the agricultural use of ammonium polyphosphate. In order to quickly obtain phase diagrams of other ammonium polyphosphate systems, local composition model of electrolyte solution was introduced to get solvent (salt)salt interaction energy parameters of the experimental system. The phase diagram calculated by regression parameters was in good agreement with the experiment, and it can be used to predict the phase diagram of other ammonium polyphosphate systems. Related Articles | Metrics Select Multi-objective optimization of separation unit for coal-based methanol aromatization Yandong GUO Hang SU Songsong CHEN Feng HUO Junping ZHANG Chin. J. Process Eng.    2021, 21 (1): 71-82.   DOI: 10.12034/j.issn.1009-606X.220078 Abstract （429）      PDF （786KB）（146）       Knowledge map    Save The development of new technologies for synthesizing xylene from methanol has great significance in China, as the coal-based chemical products have been redundant and homogeneous seriously. Due to the challenge of high energy consumption in the chemical separation process, a multi-objective optimization research was carried out in the separation of non-aromatic hydrocarbons, benzene, toluene and xylene mixture using Aspen Plus and Matlab software in this work. The traditional two-column sequence separation process and the dividing wall column process had been simulated and optimized by NSGA-II algorithm respectively. Total annual cost (TAC), energy consumption per product flow rate (GEC), the productivity of benzene-toluene and the productivity of xylene were set as objective functions. The results showed that effect of the reflux ratio on TAC was critical. The two separation processes were compared based on the lowest TAC under the premise of satisfying the constraints. The results indicated that the lowest TAC, heat transfer cost and GEC of the dividing wall column process were reduced about 7.7%, 16.1% and 26.3% in comparison with the two-column sequence process, respectively. It implied that the dividing wall column process would be the best sustainable process in xylene production with lower TAC and GEC. Related Articles | Metrics Select Design and experiment research of the liquid accumulator in compact phase-change energy storage refrigeration system Junfei YUAN Lin WANG Zhanwei WANG Yonggang JIAO Chin. J. Process Eng.    2020, 20 (12): 1439-1447.   DOI: 10.12034/j.issn.1009-606X.219345 Abstract （397）      PDF （479KB）（136）       Knowledge map    Save Compact phase-change energy storage refrigeration system, which cools the short-time high-power electronic appliances directly, is an important thermal management system. The effective control of the temperature and pressure in the working process is the main problem to be solved during the application of the system cooling a high power heat source. In this work, theoretical analysis, design and calculation of the liquid accumulator for the energy storage refrigeration system of 10 kW heat source with NH3 as the refrigerating working medium was studied theoretically, and the experimental platform for the experimental research was also built up. The results showed that the liquid accumulator, as the constant pressure equipment of the system, played a role of replenishing and storing the working medium of the storage system during the system start-up and operation. The pressure fluctuation in the accumulator was related to heat addition, evaporation temperature, volume of reservoir and initial system pressure. The temperature fluctuation of the heat source during operation was only 1.2℃, as the volumetric ratio of accumulator to system of 1.48. The coupled working characteristics of the condensing reservoir and the accumulator can restrain the temperature and pressure fluctuation of the system, when the heat source was disturbed. Related Articles | Metrics Select Influence mechanism of surface properties of coal and kaolinite on coagulation process Xixi WANG Yuan HUANG Yue SUN Mengyun SHI Anran NIU Zhe LIN Chin. J. Process Eng.    2020, 20 (12): 1448-1454.   DOI: 10.12034/j.issn.1009-606X.219369 Abstract （369）      PDF （559KB）（150）       Knowledge map    Save Coal slime water contains a large amount of clay minerals such as kaolinite, which brings great difficulties for flocculation and sedimentation. In order to clarify the influence mechanism of these mineral properties on the coagulation process, the interaction between the particles of coal or kaolinite were calculated by the extended DLVO theory, and the coagulation process of 20 g/L coal and kaolinite suspension with a CaCl2 dosage of 4.5 mmol/L was monitored by a focused beam reflectometer at the stirring speeds of 60, 100 and 150 r/min. The results showed that the electrostatic interaction played a dominant role in the range of 2?200 nm for particle surface distance. The kaolinite particles had larger electronegativity, so it was more difficult to approach to and collide to each other during the coagulation process. The higher rotation speed increased the momentum of particles and was beneficial to increase the collision frequency and shorten the time required to complete the coagulation. Under the experimental conditions, the coagulation times of coal and kaolinite were shortened from 74 and 123 s to 47 and 89 s, respectively. The hydrophobic force played a leading role in the range of particle spacing less than 2 nm, which determined the adhesion efficiency of the particles. With strong hydrophobic surface, coal particles were easier to adhere to each other after collision, and can resist higher fluid shearing action. As the result, coal particles can agglomerate to form large agglomerates of 100 μm from its initial size of 19.32 μm, while kaolinite was difficult to obtain agglomerates larger than 30 μm due to their hydrophilicity. Related Articles | Metrics Select Flotation mechanisms of rutile in synergistic system composed by sodium oleate and sodium benzohydroxamide Mingbao LIU Wanzhong GUO Siyu TIAN Mei CHEN Chin. J. Process Eng.    2020, 20 (11): 1296-1303.   DOI: 10.12034/j.issn.1009-606X.219332 Abstract （409）      PDF （879KB）（116）       Knowledge map    Save The flotation behaviors of rutile in combined regent system of sodium oleate (SO) and sodium benzohydroxamide (BHA) were studied via pure mineral flotation test. The interactions between reagents, reagents and mineral as well as the effect of the reagent combination on rutile flotation had been investigated through several measurements, including Zeta potential, contact angle, surface tension, UV diffuse reflectance spectroscope, concerning the interface chemistry properties at gas?liquid interface and solid?liquid interface. The results indicated that the reagent addition sequence influenced rutile recovery significantly and the combined use of reagent had a distinct positive-synergistic effect under different pH values. The flotation recovery of rutile and synergistic effect index followed the order: adding BHA prior to SO>pre-mixed before adding>adding SO prior to BHA. The electron-rich double bond in SO may interact with the electron-deficient benzene ring in BHA to form diverse interionic/intermolecular association complexes. The amount of the complex presented as the optimum configuration on mineral surface was critical for the synergistic effect of reagent combination and rutile flotation behavior. The effect of reagent combination on flotation recovery rate agreed well with that on the rutile bandgap width according to the UV diffuse reflectance spectroscope spectrum of rutile sample after interacted with the reagent combination under various conditions.with the electron-deficient benzene ring in BHA to form diverse interionic association complexes. The amount of the complex presented as the optimum configuration on mineral surface is critical for the synergistic effect of reagent combination and rutile flotation behavior. The effect of reagent combination on flotation recovery agree well with that on the rutile bandgap width according to the UV diffuse reflectance spectroscope spectrum of rutile sample after interacted with the reagent combination under various conditions. Related Articles | Metrics Select Optimization on bottom blowing+side blowing lead smelting for utilizing of lead?silver leaching residues Ze YANG Yaru CUI Yu HAO Lü ZHAO Zhengmin WANG Tingliang ZHANG Junxue ZHAO Fan ZHU Chin. J. Process Eng.    2020, 20 (11): 1304-1312.   DOI: 10.12034/j.issn.1009-606X.219376 Abstract （452）      PDF （1081KB）（134）       Knowledge map    Save The comprehensive recovery and complementation of lead and zinc resources is the main developing trend for lead and zinc enterprises. This work aim is to solve the problems, such as lack of heat in oxidizing smelting, difficulty in process control of slag, poor stability of reducing slag, etc, emerged in the bottom blowing-side blowing lead smelting system mixed with lead?silver leaching residues in Hanzhong Zinc Industry Co., LTD. On the basis of comprehensive evaluation of the original process, thermodynamic analysis on dominant region and phase diagram of melting process were calculated, the slag properties were determined, and subsequently, optimizing process based on regulation of slag system were put forward. The results showed that the temperature of oxidizing smelting was raised to 1050℃ and the reduction smelting was lowered to 1250℃, though adjusting heating mode of the bottom blowing furnace from sulfur to bituminous coal and pyrite as auxiliary. The direct lead-smelting process mixed with lead-containing residues can be operated smoothly though controlling reduction smelting slag, in which FeO/SiO2 mass ratio was 1.2?1.6, CaO/SiO2 mass ratio was 0.4?0.6, and ZnO≤20wt%. After process optimization, the ratio of oxygen to material decreased from 120 Nm3/t to 110 Nm3/t, and the proportion of lead?silver leaching slag mixed in charge materials increased to 24wt%. In the meanwhile, the dust content of smelting flue gas in oxidation and reduction smelting reduced by 13.47% and 15.82%, respectively, and the cost of crude lead reduced by 10.63% as a result. Related Articles | Metrics Select Investigation on the spreading dynamics of metal powder based on discrete element method Wenguang NAN Yiqing GU Chin. J. Process Eng.    2020, 20 (11): 1313-1320.   DOI: 10.12034/j.issn.1009-606X.220210 Abstract （466）      PDF （2229KB）（220）       Knowledge map    Save The use of Additive Manufacturing (AM) is increasing at a fast rate in wide ranging industries, aerospace, medical technology, transport and energy. One of the manufacturing methods used in this field is based on powder processing, but its major bottleneck is associated with the quality of particle spread layer in the powder spreading process, as its underlying particle dynamics remains unknown, which is sensitive to the type of spreader and the cohesive interaction between particles. Here, the particle dynamics in the powder spreading process for a gas-atomised metal powder was explored by discrete element method (DEM), using the most realistic physical and mechanical properties of the particles. The velocity and trajectories of particle within the heap, and the quality of the particle spread layer, were compared in the blade and roller spreading processes. Their sensitivity to the cohesive interaction between particles were also explored. The results showed that compared to blade spreading, there were several velocity bands in cascading style and particle convection within the heap in the roller spreading process, due to the rotational motion of the roller spreader. Before the formation of particle spread layer in roller spreading, the particles needed to climb upward and slip downward along the edges of heap, resulting in longer trajectories of particles. With the increase of particle surface energy, the total particle volume of spread layer was reduced in both blade and roller spreading. Compared to blade spreading, the total particle volume of spread layer in the roller spreading was smaller and more sensitive to particle surface energy. This could be attributed to the formation mechanisms of particle spread layer, i.e. the ability of particles within the heap entering into the gap region between the rough base and spreader, and the drag effect of particles by the spreader in the gap region. Related Articles | Metrics Select Effects of salt ions on the hydration and expansion characteristics of montmorillonite Yuanqing TAO Kefeng YAN Xiaosen LI Hao CHEN Chin. J. Process Eng.    2020, 20 (10): 1182-1189.   DOI: 10.12034/j.issn.1009-606X.219364 Abstract （504）      PDF （786KB）（89）       Knowledge map    Save As an important component of natural gas hydrate reservoir, montmorillonite is of great research significance to the exploitation and application of natural gas hydrate. The inhibition of salt ions in seawater on the hydration expansion of montmorillonite has important effects on the distribution of free water and bound water in hydrate reservoirs. Water content in montmorillonite with NaCl solution was measured by thermogravimetric method combined with several pretreatment methods (the centrifugal method, the direct drying method and the freeze-dried method). The effects of salt concentration on bound water and free water content of montmorillonite were analyzed. The variations of total water content and bound water content in montmorillonite with different NaCl solution concentration were discussed. The hydration and expansion characteristics of montmorillonite and the inhibition of salt ions were studied. The results indicated that the hydration expansion of montmorillonite was inhibited by salt ions. The existence of salt ions reduced osmotic hydration force. Meanwhile, it affected the van der Waals force between water molecules, the hydrogen bonding force and the electrostatic attraction force between water molecules and the surface of montmorillonite. The total water content of montmorillonite decreased with the increase of salt ions concentration. In the same time, bound water content of montmorillonite was inverse related to the salt ions concentration, and approached the minimum when the salt ions concentration was 0.2 mol/L, as the inhibition effect of salt ions on the hydration expansion of montmorillonite reached the peak. When the ion concentration was greater than 0.2 mol/L, the content of free water and bound water did not change significantly with the increase of salt ion concentration. Therefore, the study on the influence of salt ions on hydration and expansion characteristics of montmorillonite, so as to further explore the influence of salt ions on the formation of hydrate in montmorillonite, has important guiding significance for the study of hydrate distribution characteristics in deep-sea sediments. Related Articles | Metrics Select Thermodynamic and kinetic analysis of the process of preparing Al?Si alloy from polysilicon cutting waste by diamond-wire Ting XIAO Guoqiang Lü Junpeng WANG Xiongdong YANG Wenhui MA Chin. J. Process Eng.    2020, 20 (10): 1190-1197.   DOI: 10.12034/j.issn.1009-606X.219333 Abstract （412）      PDF （2449KB）（223）       Knowledge map    Save The diamond wire saw powder composition and its silicon oxides were analyzed by X-ray diffraction analysis (XRD), X-ray fluorescence spectrum analyzer (XRF) and Fourier transform infrared spectrometer (FT-IR). The possible reaction process for alloying between aluminum and diamond wire saw powder was analyzed, and its thermodynamics were determined by HSC Chemistry 6.0 software. The kinetics process of aluminum thermal reduction of SiO2 was discussed, and the Al?Si alloy preparation by using diamond wire saw powder with aluminum was experimentally investigated. The results showed that the diamond wire saw powder melted with aluminum in different mole proportion during the alloying process at the temperature range of 800~1600℃ with the influence of electromagnetic stirring. Meantime, SiO2 impurities can be reduced to Si during aluminum thermal reduction. The apparent activation energy was 364.1 kJ/mol, while the reaction order was 0.91. Finally, phase composition of alloy and slag were analyzed by EPMA, XRD, and the results were in agreement with the thermodynamic and kinetic analysis. This work provided a new idea for effectively solving the problem of silicon waste recovery and utilization during the photovoltaic industry. Related Articles | Metrics Select Studies on association equilibrium of Mg 2+ and SO 4 2+ by confocal Raman spectroscopy Bo YAN Huan ZHOU Shuixiu LI Chin. J. Process Eng.    2020, 20 (9): 1063-1073.   DOI: 10.12034/j.issn.1009-606X.219349 Abstract （382）      PDF （537KB）（105）       Knowledge map    Save Magnesium Sulfate solution is an important electrolyte solution which is widely used in many fields. The characteristics and the association equilibrium of Mg2+ and SO42- have been the focus of attention, which has important application values. In this paper, the characteristic of ion association structure of Mg2+ and SO42- in different concentration MgSO4 solutions at different temperature were studied by Raman Spectroscopy combined with Gauss-lorentz peak fitting program. Furthermore, the ion association equilibrium constant KR of MgSO4 solutions were calculated. Furthermore, the apparent thermodynamic parameters of the associated reaction of Mg2+ and SO42? and the product of the contact ion pair CIP′under standard state were inferred. The spectra experiments results showed that the peak area and peak intensity of the ν1-SO42? characteristic peaks in MgSO4 solution were linearly associated with the concentration of SO42?. The free SO42- ion was the main structure of ν1-SO42? characteristic peaks. During the process of the temperature increasing for high concentration of 1.5mol/L and 2.0mol/L MgSO4 solution, the peak area and peak intensity of the ν1-SO42? characteristic peaks decreased, red shift phenomenon occurred in the peak position, and the symmetry of the peak changed. Accordingly, the content of free SO42- ions decreased, the chance of monodentate contact ion pairs (CIPs) increased, but the content of bidentate CIPs and SO42- groups structure changed irregularly. Likewise, the ion association equilibrium constant KR of MgSO4 solution increased which showed that the ion association equilibrium moved to the right with the temperature increasing for 1.5mol/L and 2.0mol/L MgSO4 solution, thus more CIPs generated. In dilute MgSO4 solutions, there were almost no bidentate CIPs and SO42- groups structure detected, the ion association structure of ν1-SO42? characteristic peaks and KR value changed irregularly. At the same temperature, the KR value decreased exponentially with the increasing of the concentration of MgSO4 solution. Related Articles | Metrics Select Effect of P 2O 5 on lime dissolution process in steelmaking slag Yanbo CAO Yunjin XIA Jie LI Dingdong FAN Chin. J. Process Eng.    2020, 20 (9): 1074-1081.   DOI: 10.12034/j.issn.1009-606X.219324 Abstract （508）      PDF （1545KB）（146）       Knowledge map    Save The dissolution behavior of lime in two groups of slag systems under static conditions was studied by introducing lime blocks with an average size of φ15 mm?10 mm into CaO?SiO2?FeO and CaO?SiO2?FeO?P2O5 slag at 1400℃. The results showed that four areas were formed along reaction interface around in two slag, namely base slag layer, C2S permeable layer, calcium ferrite permeable layer and lime layer. C2S permeable layer and calcium ferrite permeable layer were formed by the interpenetration of Ca2+ in lime and Fe2+ in liquid slag. The presence of a dense solid phase layer in the permeable layer affected the dissolution of lime. The calcium ferrite layer in the permeable layer was gradually replaced by C2S layer. The thickness of C2S layer increased and reached maximum. Finally C2S layer was dissolved in liquid slag. The dissolution rate of lime in the two groups of slag was similar in reaction time of 5~60 s, and the dissolution rate of lime in phosphorus-containing slag was significantly accelerated in reaction time of 60~80 s. When P2O5 was added to the slag, phosphorus was dissolved in C2S to form a C2S?C3P solid solution layer. The formation of this layer will displace FeO into the slag, improve the permeability of the slag, and accelerate the dissolution of lime. Related Articles | Metrics Select Continuous flow synthesis of methyl acetoacetate in microchannel reactor Jianwu LIU Han JIANG Shenghu YAN Yue ZHANG Jiefa SHEN Daixiang CHEN Chin. J. Process Eng.    2020, 20 (9): 1082-1088.   DOI: 10.12034/j.issn.1009-606X.219308 Abstract （540）      PDF （1194KB）（204）       Knowledge map    Save Synthesis using traditional batch reaction system has many problems. First of all, it is difficult to control temperature. Secondly, the production capacity is low, and lastly, the reaction time is more. In this work, using diketene and methanol as starting materials, a new method for synthesizing methyl acetoacetate in a microchannel reactor with variable diameter pulse structure, was explored. The method mainly studied the catalyst type, material ratio, residence time, reaction temperature, and catalyst dosage. The best combination of conditions included sodium methoxide as the catalyst, n(diketene):n(methanol):n(sodium methoxide)=1:1.1:0.02, reaction temperature of 90℃, and residence time of 90 s. Under these conditions, the conversion rate of diketene was 100% and the selectivity of methyl acetoacetate was 96.8%. Compared with the traditional batch process, the operating mode of the reaction was updated and the reaction was carried out in an entirely continuous manner. This could achieve continuous automatic control of the process, thus preventing process fluctuation, unstable product quality and safety concerns caused by intermittent manual operation. The challenge was to provide reliable guaranty of heat transfer, mass transfer, environmental protection, and safety. Through process enhancement, precise temperature control, and reduction of liquid holding capacity, the production of by-products was greatly reduced and the production capacity was significantly improved. The microchannel reactor showed strong mass transfer and heat transfer conditions, which strengthened the reaction conditions and completed the reaction in a short time. The safety parameters of the reactor were good, the liquid holding capacity in the reaction zone was small, no unstable intermediates remained, the system was closed, the amplification effect was weak, side reactions were lesser, yield was higher, reaction could be precisely controlled, product quantity increased, there was energy saving and emission reduction, and also quick response to unexpected situations. Related Articles | Metrics Select Improving the accumulation of semi-autogenous grinding mill hard stones of a copper?nickel ore in Xinjiang Qian ZHANG Qingfei XIAO Xudong WANG Sen YANG Shuai MA Chin. J. Process Eng.    2020, 20 (9): 1089-1096.   DOI: 10.12034/j.issn.1009-606X.219347 Abstract （384）      PDF （1307KB）（104）       Knowledge map    Save Aiming at the problem that the semi-autogenous grinding mill of a copper?nickel ore in Xinjiang is seriously accumulated and the fineness of the grinding products is not up to standard, based on the determination of the mechanical properties of the ore, the fineness comparison of the semi-autogenous grinding mill grinding products was studied. In the method, the steel ball medium ratio was taken as a single variable, and the comparison test of the grinding index was carried out. The discrete element method was used to verify the laboratory test conclusions. In the end, the optimal medium ratio scheme of the semi-autogenous grinding mill was determined as follows: ?150:?120=1:2. The results showed that the average specific weight was 3.36 g/cm3, the average hardness coefficient was 7.93, the average static elastic modulus was 3.11×104 MPa, the average poisson′s ratio was 0.26, the ore was moderately hard as well as the ore with brittleness and toughness existed. Under the same grinding cycle conditions, the yield of 25~80 mm fraction of the hard stone grade gradually reduced in the recommended scheme of the semi-autogenous grinding mill. The plant scheme was reversed. After the three grinding cycles, the yield of 25~80 mm fraction of hard stone in recommended scheme was 4.19 percentage points lower than that in the plant scheme. The yield of three size fraction of +100, ?2.5 and ?0.074 mm were 0.25, 13.79 and 4.80 percentage points higher than that in the plant scheme respectively. Compared with the larger scheme, the recommended scheme showed better grinding ability as well. Under the same number of grinding cycles, the yield of 25~80 mm fraction of recommended scheme reduced by 3.36 percentage points, and the fineness of ?0.074 mm increased by 2.24 percentage points. The sum of the normal energy utilization of the recommended 25~80 mm fraction was 56.19%, which was 1.82 and 2.30 percentage points higher than the plant scheme and the larger scheme respectively. The recommended scheme showed better hard stone crushing ability. The results of the simulation tests were consistent with the laboratory test results. Based on the comparison of the test results, the recommended scheme had obvious advantages. Ensuring the fineness of the grinding products was in a good level, the accumulation of hard stones was fully solved, which provided a method to learn for a similar problem for related factories and mines. Related Articles | Metrics Select Cooling characteristics and influencing factors of glass quenching process Gaowei YUE Chongchong WAN Lu WANG Yanbing LI Chin. J. Process Eng.    2020, 20 (8): 947-958.   DOI: 10.12034/j.issn.1009-606X.219337 Abstract （814）      PDF （1274KB）（142）       Knowledge map    Save Cooling law of high temperature glass in air-grid plays an important role in the stress of tempered glass, and there are many factors that affect the cooling law of glass. However, because glass moves fast in air-grid, it is very difficult to test the real-time temperature change of high-temperature glass. Moreover, the test of glass cooling for each influencing factor greatly increases the workload of workers. So the physical model of glass cooling in air-grid was established to numerically simulate the cooling law, and in order to verify the reliability of the model, the cooling law of high temperature glass had been tested in air-grid with infrared thermometers under the set parameters. After the high temperature glass entered into the air-grid, the glass temperature at different times presented a strip, which reflected the nonuniformity of glass cooling, but on the whole, the glass temperature gradually decreased with the quenching time, and the glass temperature decreased with quenching time in a negative index. The numerical simulation results were in good agreement with the test results. Then the physical model was applied to simulate the cooling law of high temperature glass with the effect of wind pressure, wind temperature, distance from nozzle to glass, speed out of the heating furnace, and round-trip speed in air-grid. The results showed that the glass temperature decreased exponentially with the wind cooling time. The greater the wind pressure was and the lower the wind temperature was, the faster the glass cooling was, that was, the wind pressure and the wind temperature had a significant influence on the cooling law of glass. Secondly, the distance of the nozzle to glass had a certain effect on the glass cooling, and the effect of speed out of the heating furnace, and round-trip speed in air-grid was not obvious. This study provided important theoretical basis for setting technological parameters of tempered glass production process. Related Articles | Metrics Select Effect mechanism of Ca 2+ and Mg 2+ in water on the floatability of specularite and chlorite Mingyang LI De LIAN Junjie HAO Yiming HU Xiangpeng GAO Chin. J. Process Eng.    2020, 20 (8): 959-969.   DOI: 10.12034/j.issn.1009-606X.220024 Abstract （452）      PDF （1459KB）（146）       Knowledge map    Save In order to research the effect of water quality on the separation of specularite and chlorite, the effect and mechanism of Ca2+ and Mg2+ on the flotation behavior of specularite and chlorite using dodecylamine (DDA) as the collector were studied via micro-flotation tests, Zeta potential measurements, Boltzmann theoretical analyses, solution chemistry calculation and molecular dynamics simulation in deionized water and tap water flotation environment, respectively. The results of micro-flotation tests demonstrated that specularite and chlorite were depressed to some extent in tap water. Compared with the deionized water system, the recovery rates of specularite and chlorite decreased by 8.01 and 8.99 percent point, respectively. In simulated tap water environment, Ca2+and Mg2+ made the recovery rate of specularite decreased by 11.91 and 18.88 percent point, respectively, while decreased by 7.44 and 15.45 percent point, respectively, for chlorite. The inhibitory effect of tap water on specularite and chlorite flotation mainly caused by the existence of Ca2+ and Mg2+. The depression effect of Ca2+ and Mg2+ on specularite was stronger than that of chlorite, and the depression effect of Mg2+was more obvious than Ca2+. The results of mechanism detection indicated that the adsorption of Ca2+ and Mg2+ shifted the surface potential of the two minerals to higher values, wakened the electrostatic adsorption reaction between DDA and the two minerals, decreased the contact angle, hydrophobicity and the concentration of RNH3+ in interface layer, increased the adsorption distance between DDA and the two minerals, increased the loose degree of DDA, which in all depressed the flotation of specularite and chlorite. The research contents provide theoretical basis of disturbance law and elimination methods of water quality for iron ore flotation. Related Articles | Metrics Select Studies on reaction kinetics and phase changes during the synthesis of ionic liquids using an in-situ low-field MRI spectrometer Yadi LIU Niklas HEDIN Lina JIA Guoying ZHAO Yi NIE Chin. J. Process Eng.    2020, 20 (7): 807-821.   DOI: 10.12034/j.issn.1009-606X.220067 Abstract （372）      PDF （1360KB）（76）       Knowledge map    Save Ionic liquids (ILs) have a wide range of applications due to their many beneficial properties. However, the production cost of ILs is still high, which is limiting further industrialization. Hence, in-depth studies of the reaction kinetics and phase changes are essential to optimize the synthesis processes for ILs and the key equipment involved. An in-situ low-field magnetic resonance imaging (MRI) device was used to monitor the reaction kinetics and phase changes that occurred during the synthesis of ILs in real time. Quantitative analysis of the ILs components in the reaction system was performed using an established two-component analysis model via 1H low-field nuclear magnetic resonance (LF-NMR) relaxometry data. This analysis allowed investigating the effects of haloalkanes chain length, halogen species, stirring speed, and temperature on the reaction kinetics of the synthesis of imidazole-based ILs. Through the detected spatiotemporal T2 distributions of the phases state during the solvent-free synthesis of the 1-buty-3-methylimidazole ([C4mim]Br) IL by reacting 1-bromobutane (BuBr) with 1-methylimidazole (MIM). This study provided a set of fast, convenient, and non-destructive technical means for the detection of different aspects of the synthesis of ILs, including detection of the residual amount of ILs in organic solvents. Meanwhile, further exploration of using low-field MRI to study the combined mass transfer and reaction kinetics in ILs systems as the studied ones could be expected. Related Articles | Metrics Select Exergy analysis of synthesis of methanol from methane based on closed loop carbon dioxide reforming process Ling SUN Lin ZHU Yangdong HE Chin. J. Process Eng.    2020, 20 (7): 822-831.   DOI: 10.12034/j.issn.1009-606X.219290 Abstract （465）      PDF （1810KB）（160）       Knowledge map    Save The process of carbon dioxide reforming to methanol is of great significance for the efficient use of carbon sources and environmental protection, used as a way to replace the traditional high energy consumption and high emission steam reforming process. With aid of Aspen Plus, the process of methane to methanol in closed loop carbon dioxide reforming was simulated. The results showed that the exergy loss of this process mainly concentrated on the chemical process, accounting for 76.47% of the total exergy loss. The combustion reaction and reforming reactions accounted for 41.62% and 27.69%, respectively, while the methanol synthesis reaction and the water gas shift reaction accounted for 3.55% and 3.61%, respectively. Compared with the traditional steam reforming methanol process in the case of a certain amount of raw material methane input, the carbon dioxide reforming methanol system reduced in exergy loss of 21.44%, in water vapor consumption of 77.02%, in overall system carbon dioxide emissions of 25.89%, and increased in methanol production of 12.03%. In addition, in order to further improve the efficiency of the carbon dioxide reforming methanol process, the impacts of temperature and pressure in the reforming process were analyzed, showing that the exergy efficiency and methanol yield of the system increased first with the increase of reforming reaction temperature, then stabilized, and the reached maximum at 980℃. And the lower reforming reaction pressure was, the more beneficial improved methanol production. Related Articles | Metrics page Page 1 of 6 Total 230 records First page Prev page Next page Last page