Study for Preparation of Industrial Ammonium Molybdate from Low Grade Molybdenum Concentrate

Abstract

The preparation of industrial ammonium molybdate from molybdenum concentrate was conducted according to the process of roasting—leaching—purification—precipitation—crystallization. The optimum technological conditions were determined: the roasting temperature was 680 °C, the roasting time was 2.5 h; in the leaching process the alkali excess coefficient was 1.2, the reaction temperature was 80 °C, the liquid-solid ratio was 3:1, the leaching time was 3 h; the amount of (NH₄)₂S added into the solution was 1.1 times of the theoretical amount, the temperature was 80–85 °C, and the terminal pH was 8.5–9 in the purification process; the density of the solution was 1.4–1.6 g/mL, the pH was 1.5–2 in the precipitation process; temperature of dissolution was controlled at 80–90 °C. The recovery of the preparation of ammonium molybdate can reach 85.18%.