摘要：

电工钢表面的涂层大多为半无机涂层，涂液中含有剧毒的六价铬，在涂层机清洗和涂层切换过程中，会产生一定量的含铬涂层废液，废液具有六价铬含量高和成分复杂的特点。为使该废液中六价铬能够还原彻底，并且防止处理试剂过量添加，采用焦亚硫酸钠作为还原剂对电工钢含铬涂层废液进行处理，分别对pH、焦亚硫酸钠添加方式和反应时间对六价铬处理效果的影响作出了研究。结果表明，六价铬还原过程的最佳pH为1.8~2.0；焦亚硫酸钠添加方式以溶液ORP（氧化还原电位）控制，当溶液ORP小于400 mV时即可停止添加焦亚硫酸钠；搅拌反应40 min使六价铬与焦亚硫酸钠完全反应，即可满足处理后六价铬质量浓度小于0.05 mg/L的处理要求。

关键词: 电工钢涂层, 含铬废液, 焦亚硫酸钠

Abstract:

Most of the coatings on the surface of electrical steel are semi-inorganic coatings which contains highly toxic hexavalent chromium. During the cleaning of the coating machine and the coating switching process，a certain amount of chromium containing coating waste liquid is generated. The waste liquid has the characteristics of high hexavalent chromium content and complex composition. In order to completely reduce hexavalent chromium in the waste liquid and prevent excessive addition of treatment reagent，sodium pyrosulfite was used as reducing agent to treat the waste liquid of electrical steel chromium-containing coating. The effects of pH，sodium pyrosulfite adding method and reaction time on the treatment effect of hexavalent chromium were studied. The research results showed that the optimal pH of the hexavalent chromium reduction process was 1.8-2.0. The adding method of sodium pyrosulfite was controlled by the solution ORP （oxidation reduction potential）. The addition of sodium pyrosulfite could be stopped when the solution ORP was less than 400 mV. Stir and react for 40 min made hexavalent chromium fully react with sodium pyrosulfite，which was able to meet the treatment requirement of content of hexavalent less than 0.05 mg/L chromium after treatment.

Key words: electrical steel coating, waste liquid containing chromium, sodium pyrosulfite

中图分类号: 

• TK223.5

• X703.1