炼锌窑渣铁精矿HCl浸出过程中硅的行为研究

摘要

The behaviors of silicon in the hydrochloric acid leaching of iron concentrate recovered from zinc kiln slag were investigated through both thermodynamic calculations and experimental studies. The results show that the variation of total chloride concentration [Cl−]T has little impact on the solubility of FeSiO3 when pH is less than 10, while the solubility of FeSiO3 gradually increases with the increase of total chloride concentration when pH is less than 10. The predominance areas of Fe2+ and Fe(OH)+ are replaced by those of FeCl+and FeCl2(aq) correspondingly. In addition, the precipitation pH of SiO2 increases from 0.73 to 1.31 when the concentration of hydrochloric acid increases from 0 mol/L to 6 mol/L. The leaching of silicon and metal values increases with the increase of leaching temperature and the concentration of hydrochloric acid. However, silicon dissolved in leaching solution will be precipitated significantly as amorphous SiO2 when the concentration of hydrochloric acid increases more than 5 mol/L, which is consistent with the thermodynamics results. The precipitation of silicon adsorbs or encapsulates on the surface of iron concentrate particles by amorphous SiO2, which leads to the decrease of leaching rate of metal.%通过热力学计算和实验分析，研究炼锌窑渣铁精矿盐酸浸出过程中硅的行为。研究结果表明：当Cl−总浓度[Cl−]T＜0.1 mol/L时，[Cl−]T的变化对FeSiO3的溶解几乎无影响；而当pH＜10时，随着[Cl−]T由0 mol/L增加至6 mol/L，Fe2+和Fe(OH)+的优势区域被FeCl+和FeCl2(aq)所取代，FeSiO3的溶解度增大，同时析出二氧化硅的临界pH由0.73升高至1.31；随着浸出温度和盐酸浓度增加，硅和有价金属的浸出率逐步提高，然而，当浸出酸度超过5 mol/L时，浸出体系中的硅极易以聚合硅酸或无定型SiO2从溶液中析出，这与热力学分析结果一致；析出的二氧化硅吸附或包裹在窑渣铁精矿颗粒表面，导致铁精矿中有价组分浸出率降低。