分质回收铜冶炼废酸中酸、砷、铜/锌的电渗析新工艺

New Electrodialysis Process for Recovering Acid,Arsenic and Copper/Zinc from Waste Acid of Copper Smelting

为了有效分离冶炼废酸中酸、砷、铜/锌,采用电渗析和双极膜处理模拟废酸,考察了运行时间、酸度、砷初始浓度、铜/锌初始浓度等对酸、砷、铜/锌分离效果的影响,并采用该工艺对铜冶炼废酸进行效果验证,同时对长期使用后的电渗析阴膜、阳膜和双极膜膜面进行分析和表征。结果表明,在运行时间大于80 min、砷浓度小于9 g/L、酸度小于5%、铜/锌浓度小于5 g/L条件下,分质得到含砷、含有价金属盐和含酸的3种溶液,其中砷分离率大于93%、铜/锌回收率大于96%、酸回收率大于97%,且废酸中90%以上的其他金属离子(如Na、K、Mg、Ca等)截留在双极膜盐室,有效实现开路回收酸中无机盐离子;使用近两年后,电渗析膜和双极膜表观形貌无明显变化,无明显沉淀附着。

In order to effectively separate acid,arsenic and copper/zinc from smelting waste acid,a kind of simulated waste acid was taken to be treated by using electrodialysis with bipolar membrane.The effects of running time,acidity,initial concentration of arsenic and copper/zinc on the separation rate of acid,copper/zinc,and arsenic were investigated,and the process was also applied in the treatment of waste acid from copper smelting for verification.Besides,the surfaces of anion exchange membrane,cation exchange membrane and bipolar membrane in electrodialysis after long⁃term usage were analyzed and characterized.The results show that with the running time more than 80 min,arsenic concentration less than 9 g/L,acidity less than 5%and copper/zinc concentration less than 5 g/L,three kinds of solution respectively containing arsenic,valence metallic salt and acid were obtained.It is shown that the arsenic separation rate is more than 93%,the recovery rate of copper/zinc is more than 96%,and the recovery rate of acid is more than 97%.More than 90%of other metallic ions(such as Na,K,Mg,Ca)in waste acid are trapped in the bipolar membrane salt chamber,thus making inorganic salt ions effectively recovered from waste acid by an open circuit.After nearly two years of application,electrodialysis membrane and bipolar membrane are observed to have no obvious change in the apparent morphology,and no obvious precipitant attached on them.