Experimental Study On Recovery Of Gold From Iodine Leaching Solution By Electrodeposition

The treatment of iodized leaching solution is the subsequent part of the iodized leaching process,including the recovery of gold,the recovery and recycling of iodine and iodine solution.At present,the relevant theoretical research and treatment technology is not yet mature,if the best treatment scheme can be obtained,it can promote the industrial application of gold leaching by iodization method.In this study,iodized leaching solution was treated by electrodeposition.The research contents are as follows:?1?to determine the optimal parameters of electrodeposited gold electrolytic cell;?2?the single factor test and response surface optimization were used to determine the optimal electrodeposition gold process conditions,the electrodeposition gold kinetic model was analyzed,and the leaching liquid composition before and after the reaction was determined,and the influence of the leaching liquid composition on the gold deposition effect was discussed;?3?research was conducted on the recovery of anode iodine and the recycling of iodine solution,and the optimal treatment scheme was obtained.The main conclusions are as follows:?1?Through single factor experiment investigation type ion exchange membrane,cathode materials,anode materials and the influence on the effect of the distance between the two plates of gold deposits,it is concluded that using anion exchange membrane and graphite plate as anode,titanium plate as cathode,60 mm distance between two plates,electrolysis after 2 h,gold deposition rate and current efficiency were 95.04%and 5.12%respectively;?2?The Au-I₂-KI solution was prepared as cathode solution for electrodeposition of gold,and the initial concentration of gold in cathode solution was 20 mg·L^-1,the iodine mass fraction of anode solution was 0.6%,the anode solution n?I₂?:n?I^-?1:8,the bath voltage was 12 V,the initial pH value was 3?8,the electrolysis time was 2 h,the gold deposition effect was the best,and the gold deposition rate could reach 96.25%.The experimental results show that the technique is feasible.The gold deposition process was optimized by response surface method,and the average gold deposition rate was 96.43%under the optimized process conditions,which was very close to the predicted value of 96.6%.The electrodeposited gold process conforms to the quasi two-order kinetic model.Ag⁺and Cu²⁺in actual iodized leaching solution will affect the deposition effect of gold.The current efficiency is still too low in electrodeposited gold process.?3?When the iodine mass fraction of anodes is 0.1%?0.8%,the iodine recovery rate is only more than 70%.That is,the recovery of iodine by the principle of co-deposition is limited.When the gold concentration of cathode is more than 40mg·L^-1,the recovery of iodine is not good.The recycling experiment of iodine solution shows that when the amount of iodine in the anode solution is small(such as when the gold concentration of the cathode solution is 20 mg·L^-1,the content of the anode iodine is less than 0.6%),the iodine solution can be recycled as an electrolyte.