Sudy On The Method Of Using Membrance To Remove Chlorine In Production Of Cobalt

With the development of the society, cobalt are more and more applied to every fields ofsociety, while non-ferrous metals refining enterprises such as the cobalt, nickel and copperstill adopt the traditional electrodeposition technology in our country. The production processof these non-ferrous metals will produce large amounts of chlorine gas which is poisonousand highly corrosive has very serious impact on environment when released into theatmosphere and seriously affects the health level of front-line employees. Therefore, theimprovement of traditional electrodeposition technology to eliminate chlorine gas producedduring the process of electrodeposition can not only solve environmental problem, but alsobring huge social benefits.Cobalt electrolyte used in experiment is from non-ferrous metals refining production lineof Jinchuan Group Ltd, the main components of the electrolyte is cobalt chloride, electrolyticchlorine ions can be oxidized at the anode and release as chlorine gas when electrolyzing.Improve the traditional electrodeposition technology through the experimental comparisonand analysis, eventually, the application of3rooms with double membrane electrolysistechnology can achieve the goal of eliminating chlorine.By means of experiment on conventional electrolysis electrodeposition to produce cobalt,the optimum pH value of electrolyte was determined. Experiment shows that under thecondition of not forming cobalt hydroxide precipitation, the smaller of the pH value of theelectrolyte the harder for cobalt to separate out and the lower of current efficiency, electrolyticoptimal pH is4. Meanwhile, when the concentration of cobalt ion in the electrolyte reachesover15g/L, electric current density reach to the maximum which is96%. The analysis showsthat you must keep the cobalt ion concentration at higher concentrations to make theelectrolysis current density in a higher value.Based on comparative analysis of conventional electrolysis, double membraneventricular electrolytic method and3rooms with double membrane electrolysis technology,we finally established the3rooms with double membrane electrolysis technologyelectrodeposition to produce cobalt. Adopting double membrane electrolysis to producecobalt can not only eliminate the chlorine produced at the anode which means that a full set ofchlorine absorption system can be cancelled but also effectively improve the quality of cobalt,the current efficiency and reduce electric energy consumption of electrodeposition. Experiments determines the electrolyzer parameters, electrolyte composition of everypole compartment and main operation parameters: use circulating continuous electrolyzerwhose shape is rectangular and the sizes are as follows: B×L×H=96mm×260mm×260mm; cathode, septa and anode compartment electrolyte are respectively cobalt chloridesolution (concentration is15g/L or higher) and0.5%hydrochloric acid solution and1%sulfuric acid solution. When the current density is200A/m~2, the pH value of cathodeelectrolyte is4, electrolytic time is12hours and the current efficiency can reach above80%under this condition.Experiments determines the3rooms with double membrane electrolysis technology, thecirculating continuous electrolysis process and increases the treatment process and technicaldata of dechlorinating to anolyte，thus eliminating the chlorine produced at the anode.Experiments shows that producing per1ton cobalt electrodeposition can createeconomic benefit of1647yuan.The double membrane electrolysis eliminates the problems ofchlorine producing at the anode and has obvious both environmental and social benefits.In experiment, anode adopts titanium ruthenium coating electrode, not explore influencethat other electrode has on the elimination of chlorine at the anode, especially need furtherstudy on anode electrode materials at low oxygen evolution potential and high chlorineevolution potential. Experiment just discusses on the positive and negative membranes, needsto compare and demonstrate more ion exchange membrane and draw a conclusion ofindustrial membrane with high efficiency. Experiment without demonstrating on cyclemechanism of electrolyte, through the electrolyte circulation to keep the electrolyteconcentration in high concentration and also to achieve the effect of continuous electrolysisand stabilizing current efficiency.