| Semi-oxidized manganese ore, where some or most of the manganese ore have been oxidezed and total manganese content is approximately 15% to 25%, is a transitional manganese ore zone between the primary ore zone and the oxidized ore zone. The characteristic of this zone is composed of several valence state of manganese compounds including Mn4+(pyrolusite, MnO2), Mn3+ (braunite, Mn2O3) and Mn2+(rhodochrosite, MnCO3). The utilization of semi-oxidized manganese ore is becoming more and more important with the high-grade manganese ore reducing increasingly. In this paper, the leaching technology of semi-oxidized manganese ore was studied using pyrite and cane molasses as reductive agents in sulphruic acid medium. The content of the thesis mainly contain several aspects as follow:In technology experiments of leaching semi-oxidized manganese ore using the pyrite as reductant, the effects of sulphric acid concentration, pyrite amount, reaction time and reaction temperature on the Mn leaching rate were investigated by using single factor experiment and orthogonal designed experiment. Experiment results indicated that the order of the effects of the factors on the Mn leaching rate is the content of pyrite, sulphric acid concentration, reaction time and reaction temperature; and about 92% Mn was extracted from semi-oxidized manganese with 3.00 mol·L-1 sulphric acid concentration, in a pyrite/semi-oxidized manganese ore mass ratio of 0.2 and a liquid/solid ratio of 3:1 at 85℃ in 2 h.In technology experiments of leaching semi-oxidized manganese ore using the cane molasses as reductant, the effects of sulphric acid concentration, cane molasses concentration, reaction time and reaction temperature on the Mn leaching rete was studied by using single factor experiment. Based on the single factor experiment, the Mn leaching rate as response value and sulphric acid concentration, cane molasses concentration and reaction time as independent variables, the Box-Behnken response surface methodology was used to optimize the leaching technology of semi-oxidized manganese ore. The results showed that sulphric acid concentration was 2.82 mol·L-1, cane molasses concentration was 27 g·L-1, reaction time was 132 min, reaction temperature was 90℃, Under these conditions, the Mn leaching rate was about 92%.Reserching an approach of increasing Mn leaching rate by using preroasting semi-oxidized manganese ore, and the effects of roasting temperature and roasting time on the Mn leaching rate was investigated respectively. The results showed that the way using preroasting-reductive acid leaching could increase Mn leaching efficiency from the semi-oxidized manganese ore. The leaching of manganese was respective 98.30% and 97.13% under 800 ℃ of roasting remperature and 30 min of roasting time by using pyrite and cane molasses as reductive agents to leach the semi-oxidized manganese ore. XRD denoted that after roasting, nearly all MnCO3 in the semi-oxidized manganese ore was reduced to Mn2O3. |
PDF Full Text Request