The Study Of The Extraction Recovery Of Molybdenum From The Alkaline Leaching Solution Of The Eliminating Molybdenum Slag

The thesis was based on the study of the eliminating molybdenum slag which was generated by the APT producing program in GanZhou city. The Molybdenum was recovered by alkali leaching-solvent extraction method. The extraction rate of the Molybdenum in different extraction conditions, the back extraction rate of the Molybdenum in different back extraction conditions, the extraction mechanism and the extraction dynamics were studied. It could be some reference value on the recycling of the Molybdenum in the eliminating molybdenum slag.Different organic phase were used in the extraction experiments and the result showed that the carbonate extraction N263, Secondary caprylic alcohol and kerosene as the organic phase. The extraction mechanism of the Molybdenum by N263 extract in alkaline solution showed that the logarithmic of the Molybdenum extraction distribution ratio lgD and the logarithmic of the extractants concentration lg [(R3NCH3)2CO3]o were the linear relation and the slopes of curve was near 1. Maybe the influence of the polymerization reaction in the extractants or the competitive effect between the OH" and MoO4^2- were the reason. The thermodynamic analysis showed that the enthalpyΔH was-2.19kJ/mol when the N263 was used to extract the Molybdenum in the alkaline solutions. The extraction of the Molybdenum was a micro-heat process and it was disadvantage on the extraction of the Molybdenum when the temperature raised. The extraction dynamics results showed that:There was a little affect on the extraction of the Molybdenum when the stirring strength or the interface contacting area changed, and the reaction could reach equilibrium in short time. The extraction of the Molybdenum in the alkaline solutions was "diffusion-control".As the suitable optimum extracting conditions were got through orthogonal experiments, the factors of the extraction rate of Molybdenum were investigated in the thesis, including the initial pH in the solution, the extractants concentration, the additive agent concentration, the Molybdenum concentration in the feed solution and the O/A phase ratio. When the concentration of the Molybdenum was lOg/L, the organic phase concluding 20 percent carbonate N263 as extraction agent, secondary 20 percent caprylic alcohol as additive agent and 60 percent kerosene as diluent,12.5 of the initial pH in feed solution,1:1 for the proportion of organic and inorganic,15 minutes for extraction demixing time,800rpm for agitation speed, and 5 minutes for phase separation time, the extraction rate of the Molybdenum could reach 87.4%. Under the condition of 1.0mol/L for sodium chloride solution concentration, 1:1for the organic phase ratio(O/A),800rpm for stirring speed,10 minutes for shaking time, and 5 minute for phase separation time, the rate of single-stage stripping could reach 86%.It could achieve the closed cycle when the raffinate return to the leaching process. It was not only can achieve the recycling raffinate, but also can achieve zero discharge of wastewater, accessing to certain economic and environmental benefits.