Research On Preparation Of Molybdate By Hydrometallurgy From Low Grade Ore And Molydbenum Slag

Molybdenum is a rare and non-renewable resource. Now there are more than 20 molybdenum minerals in the world, but there are only four of them have industrial value .In all the molybdenum minerals, the molybdenite are widely used. About 99% of molybdenum exists in the form of molybdenite. Low-grade molybdenite occurs in the process of molybdenum ore flotation, it is a kind of mineral with high impurity content and week activity. It is high investment and poor applicability for the traditional pyrometallurgy and also produced wastes, polluted environment. In this paper we recover the molybdenum from low-grade molybdenite and residue, which realizes the complex using rate of the resource and also can increase the income of the corporations and effectively decreases the pollution of fume of molybdenum.In this study, we adopt hydrometallurgy to leach the molybdenum from low-grade molybdenite and residue which contain main calcium molybdate, then product ammonium molybdate directly.First, the preparations of the low-grade molybdenite and residue sample are carried out. Then adopt sodium hypochlorite and sodium carbonate to process sample. The molybdenum contents in sample are determined with 6.2 % and 8.23 % respectively, other constituents contents are determined by ICP-AES.The low-grade molybdenum is leached by sodium hypochlorite and then the optimal condition is determined. The thermodynamic and kinetics analysis on the low-grade molybdenite is also studied. Results show that: the optimal technological parameters of leach are : the ratio of liquor to solid is 17:1, leaching temperature is 30℃, leaching time is 1h. Under the optimal technological parameters, leaching ratio could reach 83.40%. The values of Gθwere negative and the absolute values of them were high in the leaching reaction. In the view of thermodynamic point , MoS2 could be leached by sodium hypochlorite theoretically. That reaction equilibrium constants show that it is a typical irreversible reaction .Leaching reaction in line with empirical Arrhenius, Ea =13.8kJ/mol, Leaching reaction can be complete.The residue which contains main calcium molybdate is also study the optimal condition, finally, Synthetic ammonium molybdate directly. For the residue, the optimal technological parameters of leach are: the concentration of leaching solution is 10%, the ratio of liquor to solid is 5:1; leaching temperature is 80℃; leaching time is 1.5 h. Under the optimal technological parameters, leaching ratio could reach 81.29%.Molybdate made by the low-grade molybdenite after product analysis by XRD can get for: （NH₄）₂（Mo₂O₇）, the purity is 76.0%. molybdate made by the industrial residue get acid sinking products: （NH₄）₂Mo₃O₁₀; Second acid sinking products: （NH₄）₂Mo₄O₁₃ . The purity is 43.69% and 91.89% respectively.