Separation And Recovery Of Silver Form Silver-manganese By Hydrometallurgical Process

Silver mineral resources are non-renewable and becoming exhausted. This is mostly due to the tremendous growth of silver demand in photography, decorative, silverware, jewelry and minting coins industry. In china, the exhaustion of silver ores has driven scholars and policy-maker to study the feasibility of mining silver-manganese deposit which occurs mainly as low grade ore in order to recover the silver.In this study, the separation and recovery of silver from silver-manganese ore by hydrometallurgical process is investigated through, magnetic separation, reductive acid leaching of manganese using sucrose as reductant, spiral concentrator desliming, leaching and silver recovery. This process route was used to design a friendly environmental flowchart for silver extraction. Test results showed that the separation and recovery of Ag by this hydrometallurgical technique is successfully achieved.Magnetic separation tests indicate that Slon-100 cyclic pulsating high gradient magnetic separator can effectively remove the impurities and upgrade the concentrate. The effects of sample particle size and various other reduction parameters on the efficiency of Slon-100 magnetic separation were studied. Under the optimum experimental conditions, the manganese content in the ore increased from 13.68% to 21.87%, and the concentrate grade of Ag increased from 185 g/t to 318 g/t by this method.In the sucrose leaching test of the silver-manganese magnetic concentrate ore, about 95.21% of Mn was extracted and 93.71% of silver was recovered from the residue within 2 hours. The optimum condition was obtained at 80% (g/g) of sulfuric acid, ratio of sucrose to ore 1:7, ratio of liquid to solid 3:1, and at temperature of 80 C. During the experiment, the content of Ag was upgraded in the residue to reach 483 g/tTo perform efficient spiral concentrator desliming and restrict the lighter particles to move into the narrowed inner part, the conditions need to be fixed as follow:pulp density of 25%, water wash flow rate of 15 L/min, particle size of 0.074 mm and the Ag concentrate grade is 2234 g/t for 89.27% of recovery.The optimized condition for silver extraction from the deslimed leaching reductive residue was as follows:Jinchan leaching agent (JC) concentration of 4 kg/t, pH of 11.2 leaching time, leaching temperature and the liquid/solid ratio of 14-16 h,25℃ and 2:1, respectively. Under these conditions, the silver recovery was approximately 86%. The precipitation rate of silver reached 92.18% in the zinc-dust precipitation experiment under the condition of Zn concentration of 2 g/L and 30 min of reaction time.Through the technique including wet magnetic separation, reducing leaching, gravity desliming, silver leaching with Jinchan leaching agent follow by zinc-dust precipitation process, the silver recovery was over 90%.It appears that sucrose leaching studied are promising for environmental applications, especially in sugar industry, where cane molasses should be removed. Hence, environment-friendly Jinchan leaching agent which compared with sodium cyanide, is a non-toxic low-cost process with a high leaching speed, should be universally adopted as an alternative leaching reagent for silver.According to these results, it can be concluded that by comprehensively applying these upgrading and hydrometallurgical strategies, satisfactory silver extraction from silver-manganese is realizable in order to achieve a development that meets the needs of the present without compromising the ability of future generations to meet their own needs.