蔗髓低温还原焙烧-浸出低品位软锰矿工艺

Reduction Roasting and Leaching of Low-grade Pyrolusite with Bagasse Pith at Low Temperature

以蔗渣造纸工业废弃物蔗髓为还原剂,研究了低温焙烧还原浸出软锰矿的新工艺.考察了蔗髓与软锰矿中锰的质量比、焙烧时间、焙烧温度、搅拌速率、浸出温度、浸出时间、H2SO4浓度和液固比对锰浸出率的影响,并分析还原焙烧过程.结果表明,锰浸出率随蔗髓用量、焙烧时间、焙烧温度、搅拌速率、浸出温度、浸出时间、H2SO4浓度和液固比增加先增加然后基本保持不变.蔗髓热解生成还原性气体有机物将软锰矿中高价锰氧化物MnO2还原为低价MnO.适宜的焙烧还原浸出条件为:蔗髓/锰质量比0.62:1、还原焙烧温度350℃、还原焙烧时间60 min、浸出搅拌速率200 r/min、浸出温度60℃、浸出时间40 min、H2SO4浓度3.0 mol/L、液固比6 mL/g.在此条件下,软锰矿的浸出率可达97%.

A new reduction roasting-leaching technology at low temperature was developed by using bagasse pith, a fibrous residue from the production of paper with bagasse, as reducing agent. The effects of mass ratio of bagasse pith to manganese in the ore, reduction roasting temperature, reduction roasting time, leaching temperature, leaching time, stirring speed, sulfuric acid concentration and the liquid/solid ratio on the leaching rate of manganese were investigated. The results showed that the leaching rate of Mn first increased and then kept constant with the increase of the mass ratio of bagasse pith to manganese, reduction roasting temperature, reduction roasting time, leaching temperature, leaching time, stirring speed, sulfuric acid concentration and liquid/solid ratio. MnO2 in the pyrolusite was converted to MnO by the reductive organic gasses forming in the pyrolysis of bagasse pith. The optimal conditions were obtained： the mass ratio of bagasse pith to manganese of 0.62：1, reduction roasting temperature of 350 ℃, reduction roasting time of 60 min, leaching stirring speed of 200 r/min, leaching temperature of 60 ℃, leaching time of 40 min, sulfuric acid concentration of 3.0 mol/L and liquid/solid ratio of 6 mL/g. The leaching rate of Mn was up to 97% at the optimal conditions.