Stepwise Leaching Of Manganese Ores And The Degradation Kinetics Of Glucose

Manganese is a kind of strategic resource,plays an important role in the national economy.For many years,the processing of manganese ore resources mainly focus on the utilization of manganese carbonate ore.That makes the reserve and grade of manganese carbonate ore fallen sharply,while substantial reserves of low grade manganese oxide ores have not been widely exploited for technical and cost problems.So it is urgent to seek a reasonable craft to utilize the existing resources.The leaching features have been different between manganese oxide ore and manganese carbonate ore,which can make full use of it by taking the stepwise leaching method of the kinds of ores in a reasonable process.Hence,the study focused on the conditions of stepwise leaching manganese oxide ore and manganese carbonate ore,and the degradation kinetic model of glucose during the reaction had been discussed.The main contents were as follows:In the stepwise leaching experiments,orthogonal and single factor experiments had been employed to investigate the effects of the concentration of H2SO4,dosage of glucose,reaction temperature and reaction time of Mn leaching rate in the first leaching stage.Then adding anolyte and manganese carbonate ore in reactor,the effects of the dosage of manganese carbonate ore,the second stage of reaction temperature and reaction time on Mn leaching rate and residual acid concentration had been studied.The results indicated that the concentration of H2SO4 4.37 mol�L-1,glucose/manganese oxide ore 0.063 g�g-1,liquid-solid ratio 1.5,reaction temperature 90? and leaching 3 h in the first reduction leaching stage.Then the leaching process had been continued for 3 h at 90? through adding manganese carbonate ore(1.5 times quality of manganese oxide ore)and anolyte.Under these conditions,Mn leaching rate reached 96.10%,and the concentration of residual acid dropped to 9.39 g�L-1.The higher leaching rate of manganese oxide ore and lower organic residuals could be obtained by using glucose and ferrous powder as reducing agents in the stage of reducing organic in solution.In addition,the concentration of residual acid could be reduced apparently by adding manganese carbonate ore in the third leaching stage.The optimal stepwise leaching process as follow:the first leaching stage,glucose/manganese oxide ore 0.027 g�g-1,the concentration of H2SO4 3.43 mol�L-1,liquid-solid ratio 2,reaction temperature 90? and leaching 3 h;the second stage,Adding anolyte and adjusting the temperature to 50? after the first leaching stage ended,then adding ferrous powder(0.047 times quality of manganese oxide ore)to react 0.5 h;the last leaching stage,adjusting the temperature to 90�C,then adding manganese carbonate ore(1.5 times quality of manganese oxide ore)to continue leaching 3 h.Under these conditions,Mn leaching rate reached 97.67%,while the concentration of residual acid dropped to 5.23 g�L-1 and the concentration of COD was lower than 10mg�L-1.In the leaching process,the effects of the concentration of glucose and H2SO4,the manganese oxide ore dosage and the reaction temperature on the degradation kinetics of the glucose were investigated.The experimental data for the degradation rate of glucose were fitting and the kinetic model was established.The apparent activation energy of degradation kinetics model was 41.80 kJ�mol-1,and the apparent reaction order was 2.0,0.927 and 0.976 for COD,H2SO4 and manganese oxide ore respectively.Where C1 was H2SO4 concentration(mol L-1),C2 was COD concentration(mg�L-1)and C3 was manganese oxide ore dosage(g�L-1).