Method for separating molybdenum from aluminium in alkaline solution

Abstract

The invention provides a method for separating molybdenum from aluminium in alkaline solution. The method is characterized in that alkali metal hydroxide is added; the consistency of free alkali is controlled within 1.20-1.80mol / L; according to the molar ratio of 0.95-1.05 of Al:Si, alkali metal silicate solution is added under mixing condition at the normal temperature within 3 hours; the mixing condition is kept, the temperature is increased to the gelatinizing temperature of 50-80 DEG C and the gelatinizing temperature is kept for 2 hours; subsequently, the temperature is increased to the crystallization temperature of 90-110 DEG C and the crystallization temperature is kept for 3-5 hours; after filtration and separation, aluminosilicate precipitate and molybdate solution are obtained; after separation, the content of molybdenum in the aluminosilicate precipitate is reduced to below 0.2%wt, the content of aluminium or silicon in the filtrate is reduced to below 0.5g / L, the precipitation rate of the aluminium or the silicon is more than 98%. More than 98% of the soluble molybdate in the molybdenum filtrate is remained, thus achieving good separation coefficient. The method is suitable for recovering molybdenum element from waste catalyst.

Description

technical field [0001] The invention relates to a method for separating elements, in particular to a method for separating molybdenum and aluminum. Background technique [0002] Molybdenum is a rare and precious element and also a major catalytic element. It often plays its role together with aluminum as a carrier in chemical catalysis, such as Ni-Mo / Al for petroleum hydrodesulfurization and catalytic reforming. 2 o 3 、Co-Mo / Al 2 o 3 And organic chemical liquid phase hydrogenation Raney nickel catalyst Ni-Mo / Al, etc. Therefore, the recovery of molybdenum from spent catalysts has become an important source of molybdenum products. [0003] At present, in the recovery of molybdenum from molybdenum-containing aluminum-based catalysts, regardless of the acid leaching or alkali roasting-leaching process, co-leaching of molybdenum and aluminum occurs to obtain a mixed solution of sodium molybdate and sodium aluminate. The mixed solution is an alkaline solution containing molyb...

AI Technical Summary

Problems solved by technology

However, since aluminum hydroxide is a colloidal precipitate, the adsorption surface area is huge. Under the condition of high aluminum and high molybdenum concentration, the content of molybdenum adsorbed in the solid phase of aluminum hydroxide can reach as much as 2%wt, which seriously affects the relationship between molybdenum and aluminum. separate

The recovery of molybdenum in the form of barium molybdate or calcium molybdate solid precipitation has certain limitations, and the recovery rate of molybdenum is only about 90%.

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