铜离子对硫酸锌溶液中钴返溶的影响及机理

Effects of copper ion on cobalt re-dissolution from zinc sulphate solution

本文研究了对湿法炼锌过程中钴的返溶的影响因素,对反应时间,氧化,锌粉粒度,Cu2+等因素进行了系统的研究.当锌粉量一定时,小颗粒锌粉有较高的初始置换速率,但是也更容易返溶.大颗粒锌粉置换速率慢,但是几乎不返溶.添加了铜离子,返溶明显,而没有添加铜离子的溶液,虽然除钴效果稍差,但是不会返溶或者返溶不明显.然而铜离子的存在对钴的返溶究竟起着何种作用还有待于进一步研究.在锌粉置换过程中,钴返溶的正确的反应为:Zn+Co2+→Zn2++Co(s),Co(s)+2OH-→Co(OH)2+2e.

The factors affecting the cobalt re-dissolution from zinc sulphate solution in zinc hydrometallurgy, including the reaction time, oxidation, particle size of zinc powder, and Cu2＋ concentration, are summarized in the article. It was shown that the re-dissolution did not occur at all when very large-sized zinc powder was employed, but it occurred markedly with small-sized zinc powder. Meanwhile, the re-dissolution was aggravated with copper ions added, whereas no re-dissolution occurred without copper ion addition. The role the copper ion played in the cobalt re-dissolution is however unclear yet. The reaction of cobalt re-dissolution was assumed to be Zn＋CO^2＋Zn^2＋＋Co（a）,Co（s）＋2OH^-→Co（OH）2＋2e.