CaS升温浸出过程的电位-pH图

针对炼钢脱硫废渣的浸出去硫热力学研究,采用平均热容法通过热力学计算绘制出不同温度条件下CaS-H2O系电位-pH图;考察了温度对钙、硫稳定存在形式和体系中电极反应平衡关系的影响.结果表明,298 K时,硫化钙的浸出反应即可自发进行;降低pH,硫以H2S的形式逸出,增大pH,硫以S2-的形式进入浸出液.随着温度升高,有利于HS-向S2-和H2S转化和微溶物质CaSO4的浸出,提高硫的浸出率。与常温相比,高温条件下,pH>7时,更有利于钙形成Ca(OH)2和硫以S2-,HS-,SO4-2离子进入浸出液或以H2S的形式逸出.

Potential-pH diagrams for heating leaching process of calcium sulfide

In order to study the leaching of sulfur from the steel desulfurization slag,the potential-pH diagrams of the CaS-H2O system at different temperature conditions were drawn based on thermodynamic calculation by the average heat capacity method.The influence of temperature on calcium,the stable region of sulphur and the electrode reaction balance were studied.The results show that,at the normal temperature,the sulfur can be leached spontaneously;as the pH decreases,the sulphur escapes in the form of H2S;while as the pH increases,the sulphur turns into leachate in form of S2-;the rising temperature is favorable to transform HS-into H2S and S2-,the leaching of CaSO4 can increase the leaching ratio of sulfur.Compared with the normal temperature,at higher temperatures,when pH is above 7,it is more profitable to convert calcium to Ca(OH)2,and it also beneficial to turn the sulphur into leachate in forms of S2-,HS-,SO-24,or escape in the form of H2S.