摘要
本文系统分析了高离子强度下含Pb2+、Cl-、SO42-酸性溶液各离子间的平衡,计算出不同条件下PbCl2、PbSO4在高Cl-、SO42-的酸性溶液中的溶解度(mol/L)。绘制出25℃下,氢离子浓度分别为7.5、5、2.5、1、0.1(mol/L)时,PbCl2、PbSO4的溶解度(mol/L)随总硫酸根浓度[SO42-]T和游离氯离子浓度[Cl-]的关系曲面。PbCl2、PbSO4的溶解度曲面在高酸度的条件下有一交线。根据浓度积原理,将优先析出溶解度小的物质,即较低曲面所表示的物质。将各条件下,两曲面的交线对底面做投影,由投影得到的溶解平衡曲线图便可根据溶液的组成及温度条件判断出溶液中的Pb2+的析出形式。结果表明:在含Pb2+、Cl-、SO42-酸性溶液中,[H+]≥7.5mol/L、[Cl-]>2.5mol/L时,溶液中PbCl2的溶解度小于PbSO4的溶解度,PbCl2较PbSO4优先析出;随着[H+]的减小,PbSO4的溶解度逐渐减小,PbSO4较PbCl2优先析出的范围增大;[H+]=0.1mol/L时,仅仅在硫酸根浓度非常低,游离氯离子浓度非常高时,才可能优先析出PbCl2;[H+]≤0.01mol/L时,在[SO42-]T、[Cl-]可能达到的范围之内,都将优先析出PbSO4。从而较好地解释了在控制电位选择性氯化浸出高品位含金物料工艺中,分离铅时,加入了大量的SO42-,而析出铅渣99%以上是PbCl2的事实。
The reactions on the acidic Pb2^＋ -Cl^- -SO4^2- system with high ion intensity were analyzed in the present paper. The solubilities（mol/L）of PbCl2 and PbSO4 in such system were calculated. Using the results of the calculation curved surface charts showing the solubility changes of Pbl2 and PbSO4 with the [ SO4^2- ] T and [ Cl^- ] and a figure showing dissolution equilibrium of PbCl2 and ebSO4 under different conditions were obtained. The results indicate that： in the acid solution containing Pb^2＋, Cl^-, SO4^2-, when [ H ＋] ≥7. 5mol/L, [ Cl^-] 〉2. 5mol/L, the solubility of PbCl2 is lower than that of PbSO4, so the precipitate is PbCl2 but PbSO4. Along with the reducing of [ H^＋ ], the solubility of PbSO4 reduces, and the region, in which PbSO4 is the first precipitate, increases. Until [ H^＋ ] ≤0. 01mol/L, the lead ions can precipitate as PbSO4. Using this result, we can easily understand the fact that more than 99% of the total lead of leaching cinder is PbCl2 in the solution of selective chlorination leaching by controlling potential and containing a large number of SO4^2-.
出处
《贵金属》
CAS
CSCD
2008年第1期5-10,共6页
Precious Metals
关键词
湿法冶金
铅
贵锑
控制电位
氯化浸出
hydrometallurgy
lead
gold - antimony alloy
controlling potential
chlorination leaching
