Study On The Process Of Double Membrane And Three Compartment Electrolysis

Double membrane and three compartment electrolysis is used by dealing with metal waste water and recycling metal by electrodeposition. Using double membrane and three compartment electrolysis to deal with metal waste water could recycle expensive metal at the same time with a good economic benefit. This report is focus on the process of double membrane and three compartment electrolysis which does electrolysis by using Cobalt Chloride liquor as electrolytic concentrate.First, we studied the normal process of electrolysis of Cobalt by an experiment. According to the result of experiment, we got the most appropriate pH for electrolyzing Cobalt Chloride is4. With Co cathode plate and Ru-coated Ti anode plate, the most appropriate ampere density is100A/m2; And the current efficiency could reach95.45%which is the highest one. In the normal process of electrolysis, a large amount of Chloridion is oxidized at positive pole and is transferred to chlorine. It does harm to environment and cause health damage to operation staffs. With the electrolysis going, at the same time, the pH of electrolytic concentrate would be reduced as a result of lots of hydrogen ion is made by water being electrolyzed. Hydrogen ion’s overpotentia is small on the pole so that the hydrogen evolution reaction would be stronger while the density of hydrogen ion is increasing. It would influence the quality of Cobalt recycle and reduce the current efficiency in the electrolysis process.With double membrane and three compartment electrolysis, this problem could be solved. Therefore, we used the electrolytic concentrate from metal Cobalt refining product-line of Jinchuan company to do experiment with double membrane and three compartment cell in order to study the process. Then we did the comparison analysis to some important influential factors. Last, we made sure the best producing circumstance and analyze the influential levels of all factors by orthogonal experiment.In operation, we used two kinds of cation exchange membrane and two kinds of anode electrode separately to compare. In. the study, we come up with that the cation exchange membrane made by China is weaker on obstructing chlorine but better on current efficiency performance than the cation exchange membrane made by other countries; For the material of positive pole, according to the test of oxygen evolution voltage and chlorine evolution voltage between graphite electrode and Ru-coated Ti anode plate, the oxygen evolution voltage is lower and chlorine evolution voltage is higher for Ru-coated Ti anode plate. In the experiment, the current efficiency is better for Ru-coated Ti anode plate; On the basis of experiment on different ampere density, we could get the current efficiency reaches the highest number at the ampere density which was200A/m2; Doing electrolysis under different pH conditions, we found that the current efficiency was higher when the pH is4, the enrichment of metal crystal was in good condition, the surface of counter electrode was smooth, and the cobalt was silvery white with gloss.Doing orthogonal experiment with ampere density, pH, and electrolytic concentrate density, the highest current efficiency could reach85.2%with the best combination which with current density being200A/m2, pH being4, and electrolytic concentrate density being150g/L; According to the analysis of data from the orthogonal experiment,in the process of electrolysis, ampere density did most influence to result, electrolytic concentrate density is the second one, and pH had a less influence.