Fundamental Study On Extraction Of Valuable Elements In Manganese Nodules

Manganese ore and its deep processing products have been widely used to national economy each domain and is the indispensable important raw materials for metallurgy and many industrial fields. The types of manganese ore in china have mainly carbonate manganese ore, manganese oxide, symbiotic polymetallic ore, sulfur manganese ore manganese nodules ore and so on in which the manganese nodules ore is one of the important types of manganese ore in china, which contains large amount of elements such as iron, manganese and silicon, it also contains a small amount of valuable elements such as silver. The manganese nodules ore may be maked a comprehensive recycling.First of all, process of leaching manganese was studied with ferromanganese nodules as raw material and pyrite as the reducing agent in sulfuric acid solution. The paper studied the influence effect of the mass ratio between manganese ore and pyrite, the volume concentration of sulfuric acid, solid-liquid ratio, reaction temperature, reaction time, stirring speed and other factors on manganese leaching rate, and indicated that optimum leaching technological conditions were that the mass ratio between manganese ore and pyrite is 7:1, the volume concentration of sulfuric acid is 9.1%, solid-liquid ratio (mL/g) is 5:1, reaction temperature is 90℃, reaction time is 3 h, the stirring speed of 300 r/min. The manganese leaching rate could reach 98.3%. Leaching process kinetics studies showed that acid leaching process of ferromanganese ore is liquid-solid-solid phase reaction process and this process is controlled by chemical reaction process, the chemical activation energy Ea = 46.31 KJ/mol, dynamic model as follows: .chemical reaction series is 1.3549.Secondly, the paper puted forward the two-step purification method of manganese leaching liquid. The first step was removal iron, in which Fe2+ was oxidized to Fe3+ in the leaching liquid by MnO2 in the conditions of reaction temperature at 80℃ and mixing reaction 1 h, then make the iron completely precipitate by adjust pH value with ammonia. The optimal conditions of hydrolysis precipitation of iron were as follows:pH = 5.5, the stirring speed is 500 r/min, the reaction time is 90 min. The removal rate of iron could reach 99.94%, the recovery rate of manganese could reach 95.48%.The second step was removal heavy metal, in which appropriate amount of (NH4)2S was added into to precipitate heavy metals from solution, then the pH of solution was adjusted to dissolve manganese sulfide generated. Research showed that the solution pH of dissolving manganese sulfide generated in the course of precipitating heavy metals was 1, the amount of (NH4)2S solution added was 0.022 L/L which the sulfur content in the solution is 2%, manganese recovery rate could reach 99%.And then, manganese carbonate was prepared with manganese leaching liquid purified which was firstly needed to adjust the solution pH value to ensure that the manganese recovery as completely as possible. Research showed that manganese recovery rate was 99.23% when the solution pH was 9. The experiment manganese total recovery rate could reach 90% finally. The manganese content of manganese carbonate products prepared(the mass fraction of manganese) is 42.45% , it reached the qualified level of industrial manganese carbonate. SEM analysis showed that the product is spherical particles and the particle size is about 500 nm and reached the submicron level.In the end, this paper studied the leaching technology of silver from acid leaching residue of ferromanganese nodules with sodium chloride solution, in which the silver elements was leached into solution in the form of silver chloride complex. Studies showed that silver leaching rate can reach 79.36%. The best process conditions of leaching silver as follow:the manganese leaching slag quality is 40 g, sodium chloride mass concentration is 25%, the liquid-solid ratio (mL/g) is 5:1, the stirring speed is 300 r/min, the reaction temperature is 80 ℃, reaction time is 180 min and the amount of hydrochloric acid is 15 mL.