红土镍矿中MgSiO3在NaOH亚熔盐体系中的浸出反应机理

摘要

Based on the existence form of MgSiO3in garnierite, MgSiO3 was synthetized through chemical precipitation method. Through the orthogonal experimentation, the effects of reaction temperature, reaction time, liquid-to-solid ratio and concentration of NaOH on the leaching process of MgSiO3 in NaOH sub-molten salt system were observed, and the optimal experimental conditions include reaction temperature of 210℃, reaction time of 180 min, liquid-to-solid ratio of 6:1, and concentration of NaOH of 80%. Based on the optimized experiment, on-line detection for the reaction process was made by using Raman spectroscopy, XRD and IR were used to analyze the structural change of water leaching residue and explore the reaction mechanism of MgSiO3 in NaOH sub-molten salt system. The results show that, during the reaction process, the Si—O bond in the SiO4 is destroyed and the NaOH inserts itself into the silicate lattice, producing intermediate Mg2SiO4and Na2MgSiO4 products. After the alkali leaching process, Mg2+ can be separated from SiO4 array, which can be released out of the silicate in the form of Mg(OH)2.%根据硅镁型红土镍矿中镁硅酸盐存在形式，采用化学沉淀法合成MgSiO3，通过正交实验考察反应温度、反应时间、液固比和NaOH浓度对MgSiO3在NaOH亚熔盐体系中的浸出过程的影响，得出优化实验条件为：反应温度为210℃，反应时间为180min，液固比为6：1，NaOH浓度为80%。在优化实验的基础上，采用Raman光谱对反应过程进行在线检测，利用XRD和IR光谱分析反应后的水浸渣结构变化，解析MgSiO3在NaOH亚熔盐体系中的反应机理。结果表明：在反应过程中，SiO4中的Si—O被破坏，NaOH介入硅酸盐晶格中，其中间产物为Mg2SiO4和Na2MgSiO4，Mg2+经过碱浸过程可以脱离SiO4阵列，以Mg(OH)2形式从其硅酸盐中得以释放。