Separation and Recovery of Molybdenum from Acidic Solution using LIX 973 N

Abstract

Leach liquors bearing 10.682 g/L Mo, 2.411 g/L Co, and 3.842 g/L Al obtained by the acid leaching of spent hydrodesulphurization catalysts were treated for the separation and recovery of Mo(VI) leaving Co(II) and Al(III) in the raffinate using solvent extraction by LIX 973 N. Equilibrium conditions for the extraction (loading) and stripping of molybdenum(VI) were determined. Extraction of molybdenum(VI) was increased from 13.9 to 96.7% with an increase in the extractant concentration from 2.5 to 30.0% (v/v) using 30% LIX 973 N in kerosene with feed pH 1.0 and a phase ratio of O: A = 1:1. The McCabe-Thiele plot for extraction of molybdenum(VI) with 30% LIX 973 N illustrated 2-stages at 2:3 (O: A) phase ratio and the loaded organic contained 16.021 g/L molybdenum(VI) indicating complete (99.9%) extraction. Stripping of molybdenum(VI) from the loaded organic was carried out with different (NH 4 ) 2 CO 3 concentration and a maximum of 98.45% stripping efficiency resulted at the unit phase ratio. Strip solution bearing molybdenum at about 48.049 g/L was achieved in 3-counter-current stages at O: A ratio of 3:1 with 1.5 M (NH 4 ) 2 CO 3 . High purity (99.9%) molybdenum trioxide prepared from the strip solution via crystallization was confirmed from the XRD study.