The leaching process of iron and manganese in tungsten smelting slag

The analysis results of raw materials by XRF, XRD and SEM show that: the main constituent elements of Fe, Mn, and Ca were determined to be approximately 23.41%, 7.166%, and 15.22%; the higher content of iron compound crystals and manganese compound crystals are mainly Fe₂O₃ and NaMn(Mn, Fe)₂(PO₄)₃; in the tungsten smelting slag, crystalline substances are adsorbed on the surface of large particles. The morphology and size of the particles have great difference. Sulfuric acid was selected as the leaching agent for the tungsten smelting slag, and the iron and manganese were selectively leached. In the calcium-enriched filter residue, the leaching amounts of manganese and iron in the 10 g tungsten smelting slag were about 0.58 g and 2.1 g, respectively. The effects of reaction temperature, solid-liquid ratio, mass fraction of sulfuric acid and reaction time on the leaching rate of iron and manganese were investigated. The optimum conditions were obtained by orthogonal experiment table: reaction temperature 80 ℃, solid-liquid ratio 1:6 (g/g), mass fraction 25% (g/g) and reaction time 90 min. The number of leaching is 1 time. The leachate cycle leaching times can increase the concentration of iron and manganese by approximately 50% and 38%. The kinetics of the leaching process is more consistent with the control of the diffusion through the product layer, in which the iron leaching rate is faster.