Abstract
The extraction of manganese from a semi-oxidized manganese ore was investigated with sucrose as the reducing agent in dilute sulfuric acid medium. The kinetics of leaching manganese from the complex ore containing MnCO3 and MnO2 was also investigated. The effects of sucrose and sulfuric acid concentrations, leaching temperature and reaction time on the total Mn (TMn), MnO2 and MnCO3 leaching were investigated. Results showed that MnCO3 could more easily react with hydrogen ions than MnO2 in ores, and MnO2 decomposition could be advantageous for MnCO3 leaching. The leaching efficiencies of 91.8% for total Mn, 91.4% for MnO2 and 96.9% for MnCO3 were obtained under the following optimized conditions: 0.035 mol/L sucrose concentration, 5 mol/L sulfuric acid concentration, 60 min of reaction time and 363.2 K of leaching temperature. In addition, it was found that the leaching process of semi-oxidized manganese ore follows the shrinking core model and the leaching rate was controlled by chemical reaction and diffusion. The apparent activation energy of the total manganese, MnO2, and MnCO3 leaching were 40.83, 40.59, and 53.33 kJ·mol−1, respectively.
Highlights
Manganese and its products are widely used in steel, ferromanganese, non-ferrous alloys, dietary additives, fertilizers, paints, electronic components and other chemicals [1]
The effect of agitation speed on the leaching rate of total manganese was investigated in the range of 100–700 r·min−1 under the conditions of the initial sulfuric acid concentration of 5 mol/L, 0.035 mol/L sucrose and temperature of 363.2 K
A slight decrease was observed when the agitation speed increased from 500 to 700 r·min−1, and this decrease was ascribed to the violent agitation that caused the particles to adhere onto the inner wall of the three-neck flask
Summary
Manganese and its products are widely used in steel, ferromanganese, non-ferrous alloys, dietary additives, fertilizers, paints, electronic components and other chemicals [1]. China is the largest producer and consumer of manganese products in the world, annually consuming more than 14 million tons of manganese ores [2]. The efficient and economic extraction of manganese from low-grade manganese ores in China is of practical significance. As a low-grade manganese ore, semi-oxidized manganese ore is a rhodochrosite (MnCO3 ) that has been partly oxidized to manganese dioxide (MnO2 ). The mineral compositions found in ore are rhodochrosite (MnCO3 ), manganese oxide ore (MnO2 ) or mischcrystal structure of MnCO3 and MnO2
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