Abstract: Several physical and chemical analytical detection methods were used to study the basic properties of electrostatic precipitator (ESP) dust collected from Baogang Steel Corporation. The results showed that the major components in the dust were K, Na, Fe and Ca salts. Water leaching could be used for recovering the potassium salt. Massive soluble calcium sulfate existed in the leaching solution. In order to provide theoretical guidance to inhibition of the dissolution of calcium ion from the ESP dust, the water leaching experiment on ESP dust was performed, and the dissolution behaviors of CaSO4 in potassium chloride, sodium chloride, potassium sulfate and their mixed salt solutions were studied. The result showed that the solubility of calcium sulfate dihydrate increased sharply with increasing of concentrations of KCl and NaCl due to the salting-in effect of KCl and NaCl. A lower ratio of liquid to solid should be chosen in the leaching process to increase the concentration of SO42- and inhibit the dissolution of calcium sulfate dihydrate by using the common ion effect of SO42-. Using sodium carbonate solution as precipitating agent, the effect of Na2CO3 on the removal rate of calcium ion was studied. Na2CO3 was effective in removal of calcium ion. The effects of concentration of sodium carbonate solution, reaction temperature, and stirring speed on preparation of spherical calcium carbonate particles were studied. Spherical calcium carbonate particles of less than 10 μm with good dispersion and grain size distribution were obtained. Furthermore, a potassium recovery process with joint production of spherical calcium carbonate from ESP dust was designed, and the quality of KCl product was stable and met the requirements of national standard GB 20406-2006. This process had industrial application potential.

Key words: sintering dust, potassium salt, leaching, crystallization, spherical CaCO3

摘要： 采用物理化学表征方法研究了包钢烧结电除尘灰的基础性质，结果表明，该烧结电除尘灰的主要成分为Fe，K，Na，Ca的化合物，其中的钾盐可通过水浸分离回收. 浸出液中含有大量可溶性硫酸钙. 为了在浸出过程中抑制硫酸钙的溶解，考察了硫酸钙在KCl，NaCl，K2SO4及其混合盐中的溶解性能. 结果表明，由于KCl和NaCl的盐溶效应，硫酸钙的溶解性能得到提升. 应采用低液固比，提高浸出液中硫酸根离子的相对含量，利用硫酸根离子的同离子效应抑制烧结电除尘灰中硫酸钙的溶解. 以碳酸钠为沉淀剂，考察其对钙离子沉淀效果的影响. 结果表明，碳酸钠具有较好的硫酸钙沉淀效果. 在沉淀钙离子的同时，研究了沉淀剂的浓度、反应温度、搅拌强度对碳酸钙晶体形貌的影响，制备获得了分散良好，粒径小于10 mm的球形碳酸钙副产品，实现了资源综合利用. 最后设计了从烧结电除尘灰提取国标20406-2006一级氯化钾并联产球形碳酸钙副产品的工艺路线，该工艺具有工业应用潜力.

关键词: 烧结电除尘灰, 钾盐, 浸出, 结晶, 球形碳酸钙