铜冶炼过程酸浸高硅渣碱性焙烧热力学研究

Study on Thermodynamics of Alkaline Roasting of Acid Leaching High-silica Slag in Copper Smelting Process

火法炼铜吹炼过程产出大量铜渣,经酸浸处理回收铜等有价金属后会产生大量高硅渣。为了实现高硅渣的无害化处置和硅的回收利用,采用热力学软件Factsage 7.3和HSC 6.0对高硅渣碱性焙烧过程主要反应的ΔG-T图、物相平衡分配图及Na_(2)O-SiO_(2)-FeO体系相图进行计算和绘制。研究结果表明:焙烧温度和ω(Na_(2)O)/ω(SiO_(2))的变化会显著影响焙烧转型过程和产物的物相组成。理论上实现SiO_(2)转型的优化条件为:焙烧温度800~900℃、ω(Na_(2)O)/ω(SiO_(2))=0.41~0.64。高硅渣中的杂质Al和Fe参与反应过程,且不溶性杂质NaAlSiO_(4)较可溶性杂质Na_(2)FeO_(2)优先生成。根据热力学分析结果,开展了验证试验,结果表明:在碳酸钠过量系数为SiO_(2)、Al和Fe理论总用量的0.9倍,焙烧温度850℃,焙烧时间2 h的条件下,硅的浸出率达到88.56%。

A large amount of copper slag is produced in the pyrometallurgical process of copper smelting,and a substantial quantity of high-silica slag is produced after the recovery of valuable metals such as copper by acid leaching.In order to realize both the harmless disposal of high-silica slag and the recovery utilization of silicon,thermodynamic software Factsage 7.3 and HSC 6.0 were used to calculate and construct ΔG-T diagrams,phase equilibrium distribution diagrams,and phase diagrams of Na_(2)O-SiO_(2)-FeO system during the main reactions involved in the alkaline roasting process for high-silica slag.The results indicate that variations in roasting temperature andω(Na_(2)O)/ω(SiO_(2))can significantly affect the roasting transformation process and product phase composition.Theoretically,the optimization conditions for SiO_(2) transformation are determined to be a roasting temperature range of 800—900℃ with ω(Na_(2)O)/ω(SiO_(2))=0.41—0.64.Furthermore,impurities such as Al and Fe were found to participate in the reaction process within high-silica slag,and insoluble impurity NaAlSiO_(4) being formed prior to soluble impurity Na_(2)FeO_(2).According to the results of thermodynamic analysis,validation tests were carried out.The results show that the leaching rate of silicon reaches 88.56% under the conditions including excess coefficient of sodium carbonate of 0.9 times of the theoretical total amount of SiO_(2),Al and Fe,roasting temperature of 850℃,and roasting time of_(2)h.