| In the past several decades, silver-manganese ore was discovered in Hunan, Hubei, Anhui, Jiangxi, Hebei, Guangxi, Inner Mongolia and some other provinces in China. In general, the grade of Ag in silver-manganese ore is 150 g/t to more than 1000 g/t, and the grade of Mn is 10% to 30%. Silver-manganese ore is one kind of important resources of silver, the separation and recovery of Ag is of significance for industry and economy, so it is necessary to develop effective technique for processing silver-manganese minerals.The status of silver-manganese ore processing methods is reviewed. Based on thermodynamic analysis and experiments, a novel technique for processing silver-manganese mineral was developed, including reducing leaching of manganese with iron scrap as reductant, gravity desliming and silver leaching with thiourea. Test results showed that the separation and recovery of Ag by this technique is more satisfactory than that by traditional technique.The possibility of manganese leaching with iron scrap as reductant was investigated through thermodynamic calculation. As a result, the Gibbs free energy and equilibrious constant were calculated, and the raction was proved to be complete. Systematic tests and mechanism analysis of leaching manganese with iron scrap from silver-manganese ore were conducted. The results show that the leaching of manganese is affected by the grinding size of silver-manganse ore, ratio of sulphuric acid to ore and ratio of iron scrap to ore. The kinetic experiments indicated that the reaction of leaching manganese with iron scrap is controlled by diffusion and the kinetic equation is derived as follows:The approximate condition was determined by the thermodynamic analysis and the kinetic experiments, but the optimum condition needs to be determined by orthogonal experiments. The optimum condition on manganese leaching is that the particle size of silver-manganse ore 0.088 mm to 0.074 mm, ratio of sulphuric acid to ore 0.6:1, ratio of iron scrap to ore 1:12, ratio of liquid to solid 3:1, leaching time 45 min and the room temperature, and 96.67% of manganese was obtained from the lixiviation liquid and 95.48% of silver was recovered from the residue at the optimum leaching condition. Effect on separation of silver from manganese was satisfied, and the essential condintion was provided for the following process.The study on gravity desliming, reducing leaching silver with thiourea and reaplacement by zinc after the reducing leaching manganese with iron scrap was carried out. The result of gravity desliming with the helical smooth groove for the leaching residue showed that the silver grade was increased fom 473.23 g/t to 1113.10 g/t at the optimum condition and the recovery of manganese was 98.32%. The leaching rate of silver with thiourea was 96.54% under the optimum contidion of ratio of liquid to solid 12:1, [TU] 12 g/L, [Fe3+] 0.012 mol/L, pH 1.5～2.0, temperature 40℃～60℃and leaching time 120 min. And the recovery of replacement for silver was 97.73% with zinc at the optimum condition that zinc 2g/L,time 15 min, mixing speed 180r/min.Through the novel thchnique incluing rehucing leaching, gravity desliming, silver leaching with thiourea and replacement with zinc, a silver recovery of 88.57% was obtained. Without pollution, this technique is better than traditional one, and the reductant used in the technique is easily available and the cost for operation is low.
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