Abstract: Potassic rocks are aluminosilicate crystals containing abundant potassium elements, which could be used to produce K-fertilizers by extracting K+, synthesizing zeolites, and preparing valuable industrial products. To realize the efficient utilization of potassic rocks, the sub-molten salt method was used to activate potassic rocks using NaOH-NaCl as the activating agent. The effects of the addition of NaOH, NaCl, and H2O on the leaching rate of K+ were investigated, respectively. The raw materials, activated products and filtration were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and titration method. The experimental results showed that the optimal activation conditions are m(NaOH)/m(potassium rocks) of 0.7, m(NaCl)/m(potassium rocks) of 0.7, m(H2O)/m(potassium rocks) of 1.0, activation temperature of 160℃, and activation time of 120 min. The leaching rate of K+ could reach about 92%, and the alkali concentration was decreased to 41wt%. Comparative investigations were made with the effect of activation of potassic rocks using the NaOH sub-molten method concerning the leaching rate of ions of K+, SiO32- and Al3+ and activated products in the identical reaction conditions. The concentrations of K+, SiO32- and Al3+ in the mother liquor obtained from NaOH-NaCl sub-molten system were significantly increased in contrast with that from the system in the absence of NaCl, demonstrating the promotion effect of NaCl for the activation of potassic rocks and the peaks assigned to SOD zeolite were greatly intensified with the introduction of NaCl. Compared with the activation effect and conditions of other additives in the sub-molten salt method reported in the literature, NaOH-NaCl sub-molten system exhibited a satisfactory leaching rate of K+ under the condition of significantly decreased alkali concentration at a low temperature (160℃) for short time (120 min), which greatly reduced energy consumption and time wasting. According to the compositions of mother liquor after sub-molten salt activation, the circulating process for the activation of potassic rocks in the NaOH-NaCl mixed sub-molten salt system was designed to realize the recycling of NaCl. This work provides an energy-saving and effective method for the activation of potassic rocks, paving a new way to realize the comprehensive utilization of potassic rocks.

Key words: Potassic rocks, Sub-molten salt method, NaOH–NaCl, Leaching rate of K+, Zeolite SOD, Ion exchange

摘要： 为了实现含钾岩石的高效利用，以NaOH-NaCl混合碱为助剂进行亚熔盐法活化含钾岩石的研究。采用X射线衍射(XRD)、扫描电镜(SEM)及滴定法对反应前后的产物组成进行分析。结果表明，含钾岩石活化的适宜条件为：m(NaOH)/m(potassic rocks)=0.7、m(NaCl)/m(potassic rocks)=0.7、m(H2O)/m(potassic rocks)=1.0、反应温度160℃，反应时间120 min。在该条件下，K+浸出率可达92%，碱浓度下降至41wt%，低于常规亚熔盐体系的介质浓度，活化后产物为SOD沸石。通过分析合成后母液组成，设计母液的循环工艺，实现NaCl的循环利用。该法显著减少了亚熔盐活化含钾岩石过程中的碱用量，并实现矿石的高效活化，为含钾岩石的综合利用提供新途径。

关键词: 含钾岩石, 亚熔盐法, NaOH–NaCl, K+浸出率, SOD沸石, 离子交换