| There is abundant resources of lead and zinc in China, but mostly are sulphide ore with complicated composition and refractory low grade lead-zinc oxide ore. It can't be effective recovery of valuable metals with conventional beneficiation and metallurgical methods from this low grade lead-zinc oxide ore because of its complicated composition. To improve the comprehensive utilization of resources, the development of high efficiency technology to treat such ores has important practical significance.It takes low grade lead-zinc oxide ore as materials in experiments. The new technology of hydrometallurgy and pyrometallurgy for treating low grade lead-zinc oxide ore by hydrothermal vulcanization-flotation and vulcanization roasting-flotation are proposed, and the theory and experiment of key process were investigated.The thermodynamics to reaction of oxides and vulcanizing agent sulfur (or pyrite) with additives carbon (or powder iron) was calculated, the possibility of oxide ore transforms into sulfide mine was analyzed by theΔGθ-T diagrams. The main vulcanization reactions were established by the technology of XRD and chemical phase analysis.Select the representative surfaces of ZnO (001), PbO (100) and CaO (001) as adsorption surfaces, CASTEP software was used to carry out structure optimization and energy calculation of adsorbing sulfur atoms on surfaces of ZnO (001), PbO (100) and CaO (001). The results of calculation show that the oxides (ZnO, PbO and CaO) can adsorb the sulfur atoms, but the Oxygen atoms in oxides take precedence over the metal ions in the oxides to adsorb sulfur. In these oxides, the PbO is most easily to adsorb the sulfur atoms, then is the CaO, the third is ZnO.The effects of hydrothermal vulcanization time, temperature, particle size, curing agent dosage, liquid-solid ratio on sulfidation rate were studied, the optimum test conditions obtained as follows:temperature is 180℃, time is 180min,particle size is -200 mesh, the dosage of sulfur is 1.2 times of theoretical dose, liquid-solid ratio is 1.2:1.Under these conditions, the highest sulfidation rate of zinc is 76.58%. The flotation process was choosed by exploratory test of flotation reagent, process and pretreatment before flotation. In the Closed-circuit flotation test, lead concentrate obtained contents 16.82% lead, the recovery of lead is 40.35%, zinc concentrate obtained contents 22.45% zinc, the recovery of zinc is 69.31%.The effects of sulfidation roasting time, temperature, particle size, curing agent dosage on sulfidation rate were researched in tubular resistance furnace, the optimum test conditions obtained as follows:temperature is 750℃, time is 120min,particle size is -200 mesh, the dosage of sulfur is 1.0 times of theoretical dose. Under these conditions, the sulfidation rate of zinc is above 94%, the sulfidation rate of lead is above 97%.In the closed-circuit flotation test, the mixed concentrate obtained contents 37.17% zinc with recovery of 86.62% and contents 9.40% lead with recovery of 74.42%.Choiced the process of vulcanization roasting-flotation as the better technology by comparing the laboratory test flotation indices of hydrothermal vulcanization-flotation and vulcanization roasting-flotation, and the pilot test was carried out with process of vulcanization roasting-flotation, test scale is 10t/d.The pilot test was carried on limestone ore for 21 shifts, when feed grade of lead is 1.03% and zinc is 7.81%, the flotation concentrate contents 3.56% lead with 63.75% recovery and 25.74% zinc with 75.06% recovery, the tailing contents 0.35% lead and 1.49% zinc. The pilot test was carried on sandstone ore for 15 shifts, when feed grade of lead is 1.04% and zinc is 6.63%, the flotation concentrate contents 4.33% lead with 60.24% recovery and 29.12% zinc with 74.83% recovery, the tailing contents 0.38% lead and 1.20% zinc. The pilot test was carried on mixed ore (mass ration of limestone to sandstone is 1:1) for 19 shifts, when feed grade of lead is 1.06% and zinc is 7.52%, the flotation concentrate contents 4.59% lead with 64.25% recovery and 31.74% zinc with 73.79% recovery, the tailing contents 0.33% lead and 1.40% zinc.Cumulative indices of 55 shifts with limestone, sandstone and mixed ore show that when feed grade of lead is 1.04% and zinc is 7.39%, the flotation concentrate contents 4.07% lead with 63.81% recovery and 28.15% zinc with 74.60% recovery, the tailing contents 0.34% lead and 1.40% zinc.
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