Manganese leaching during high concentration flue gas desulfurization process with semi-oxidized manganese ore was studied in this paper. It was found that there were different reaction pathways among which MnO 2, Mn 2 O 3 and MnCO 3 in semi-oxidized manganese ore during flue gas desulphurization and manganese leaching. High SO 2 concentration facilitated redox reaction between MnO 2 and SO 2 , and high concentration of H 2 SO 4 accelerated MnCO 3 /Mn 2 O 3 leaching from semi-oxidized ore. Kinetics study showed that manganese leaching in flue gas desulfurization process with semi-oxidized ore was controlled by a mixed-control model, that is the surface chemical reaction and mass diffusion dominated both the oxidation of SO 2 and manganese leaching process. The apparent activation energy was 13.05 kJ·mol −1 and the reaction orders with respect to SO 2 and H 2 SO 4 concentration were 1.38 and 0.10, respectively. Finally, a semi-empirical rate equation based on shrinking core model was derived to describe the process.
Guocan Zheng,Yingchun Zhang,Qinrui Du,Yingxia Zhang,Kehao Wang,Jingxiao Du
Electrolytic manganese residue (EMR) represents a solid waste generated during the production of electrolytic manganese. Under the leaching and dissolution by rainwater, manganese, ammonia nitrogen, and heavy metal ions in EMR can infiltrate into the surrounding environment, thereby disrupting ecological balance and posing threats to human health. This study optimized the leaching conditions for manganese from EMR using ammonium persulfate(APS) through single-factor and orthogonal experiments. It was found that temperature, APS concentration, and reaction time significantly influenced the manganese leaching efficiency. Under leaching temperature of 80°C, leaching time of 3 hours, APS concentration of 30 g/L, and a liquid-to-solid mass ratio of 6 mL/g, a high manganese leaching rate of 88.91 % was achieved in a single process, and significant removal of ammonia nitrogen was observed. After enhanced leaching, the content of organic matter and the total amount of water-soluble salt were 4.10 wt% and 3.11 wt%, respectively. And it meets the requirements of the standard GB 18599–2020 for solid waste entering the class II site in China. Kinetic analysis revealed that the manganese leaching process was controlled by intraparticle diffusion within the solid phase. Mineralogical phase analysis indicated that the primary mineral structures were oxidatively decoupled and disrupted, leading to the dissociation of aggregates, which facilitated the leaching of manganese and ammonia nitrogen. This study provides a practical, green, and economical technological route for the harmless treatment of EMR.
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