Studies On Technology And Mechanism In Leaching An Copper-bearing Argentite Ore With The Method Of [Bmim]HSO₄-thiourea

Silver leaching with thiourea is gradually paid more attention by non-cyanide technologyresearchers for its outstanding characters, including fast leaching speed and insensitive toimpurity, so it is regarded as the most promising non-cyanide leaching technology. However,this technology still has some shortcomings in allusion to copper-bearing silver concentrate,such as low leaching rate, big agent consumption and so on. As a new type of green solvents,ionic liquid has excellent properties such as negligible vapor pressure and good adjustment ofsolubility.[Bmim]HSO4ionic liquid once successfully improved the thiourea leaching resultof some gold-silver ores, so further research on the behavior and mechanism of[Bmim]HSO4-thiourea leaching on copper-bearing silver ore, especially those with highcopper content be of great value to improve the utilization state of silver ore as well as itssecondary resources.The study was carried out on silver sulfide, in the system of [Bmim] HSO4-thiourea andH2SO4-thiourea this paper investigated influences of different leaching conditions, includingthiourea concentration, oxidizing agent concentration, leaching time, pH to the leachingefficiency. The result indicated that, in the optimum process parameters, for the [Bmim]HSO4-thiourea leaching system,[Bmim] HSO4concentration of0.05mol/L, thioureaconcentration of0.20mol/L, Fe2(SO4)3concentration of2×10-3mol/L, leaching time of32h,the leaching rate was98.5%; for H2SO4-thiourea leaching system, H2SO4concentration of0.05mol/L, thiourea concentration of0.20mol/L, leaching time of24h, Fe2(SO4)3concentration of4×10-3mol/L, the leaching rate was92.1%. Obviously, the leaching rate in[Bmim] HSO4-thiourea leaching system was6.4%higher than that in the HSO4-thiourealeaching system. Based on the silver sulfide leaching experiment, experiment was conductedon mixture of silver sulfide and chalcopyrite in the two systems mentioned above to find outinfluences of different leaching conditions to leaching efficiency, then a comparison wasmade between them. The result proved that [Bmim]HSO4concentration(pH), thioureaconcentration, Fe3+concentration and leaching time would affect the extraction rate. Underthe optimum technological parameters, the leaching rate in [Bmim] HSO4-thiourea leachingsystem and H2SO4-thiourea leaching system could reach92.58%and80.74%, respectively.The leaching rate in the [Bmim] HSO4-thiourea leaching system was11.84%higher than thatin H2SO4-thiourea leaching system in the same leaching condition. Pure mineral test and artificial mixture mineral test revealed that the laboratory findingsgained in pure mineral experimental by means of [Bmim] HSO4-thiourea leaching system andH2SO4-thiourea leaching system was applied to a flotation silver concentrate, the influencesof leaching conditions to leaching effectiveness were similar to that in the pure mineralexperimental system. After process optimization, the leaching rate in the [Bmim]HSO4-thiourea leaching system and H2SO4-thiourea leaching system could reach85.28%and72.16%respectively. The leaching rate in the [Bmim] HSO4-thiourea leaching system was13.12%higher than that in H2SO4-thiourea leaching system in the same leaching condition.Thus it could be seen that the method of [Bmim] HSO4-thiourea, as a safety system, will havea further development in the leaching of the actual silver concentrate.The dissolution mechanism of silver and strengthening leaching mechanism of[Bmim]HSO4was studied by some analysis test means，such as XRD, SEM, EDS and so on,the results showed that the dissolution process of silver was similar to the process in the[Bmim]HSO4-thiourea system, the better result may be related to the superior stable qualityof thiourea and the leaching product of Ag(CSN2H4)3+in the new environment.