CODcr测定废液中银的回收与利用

对重铬酸钾法测定CODCr的废液组成进行了估算,提出了以氯化银沉淀形式收集CODCr废液中的银离子,用Zn-H2SO4体系还原氯化银沉淀的方法,采用该方法可得到纯度为99.6%的金属银粉,回收率为94.8%,回收的银粉可用于CODCr的分析。回收银后的废液在碱性条件下加过量硫化钠生成硫化铬、硫化亚汞和硫化亚铁共沉淀,达到去除Cr3+,Hg2+和Fe3+的目的,清液可排放。

Recovery and Reuse of Silver from Waste Liquid of CODcr Tests

The constitute of the waste liquid from the measurement of CODCr using potassium dichromate was estimated, A method that recycling Ag+ by depositing silver chloride and deoxidizing the deposition of silver chloride by Zn-H2SO4 system was proposed. Using this method, silver powder with purity of 99.6% can be obtained, the recover rate is 94.8%, and the recovered silver powder can be reused for CODCr analyzing. The waste liquid after the silver recovery is disposed to remove Cr3+, Hg2+ and Fe3+ by dosing excessive sodium sulphide to create codeposition of chromium sulphide, mercurous sulphide and ferrous sulfide under the alkaline condition. The clear liquid can be discharged directly.