Abstract

This study focused on the exploration of a novel reductive leaching method from pyrolusite ore which can effectively reduce residual organics in leaching solution. Formaldehyde was used as a reductant to extract manganese from low-grade pyrolusite. Organic residue in the leaching solution was analyzed via HPLC. Kinetics model was also exposed. The optimized leaching conditions were as follows: H₂SO₄ concentration 2.21 mol/L, liquid-to-solid ratio 8:1, 2.5 ml formaldehydel/10g low-grade pyrolusite, stirring rate 200 r/min, leaching temperature 353 K and leaching time 120 min. The extraction ratios of Mn, Al, Fe, Mg, and Ca were 90.24%, 22.78%, 61.61%, 53.38%, and 84.2%, receptively under the optimized conditions. Formic acid was the main residual organic from the oxidized production of formaldehyde; its concentration was only 2.24 g/L. The kinetic data for leaching process obeyed a mix-controlled kinetic model. The apparent activation energy of leaching reaction was 34.81 kJ/mol for 0-30min, 30.1 kJ/mol for 30–150min, respectively.

摘要

本研究的重点是探索一种新的软锰矿还原浸出方法，该方法可以有效减少浸出液中的残留有机物。甲醛被用作还原剂从低品位软锰矿中提取锰。通过HPLC分析浸出溶液中的有机残留物。动力学模型也被曝光。优化浸出条件如下： H ₂ SO ₄浓度2.21 mol/L，液固比8:1，2.5 ml甲醛/10g低品位软锰矿，搅拌速度200 r/min，浸出温度353 K，浸出时间120 min。在优化条件下，Mn、Al、Fe、Mg和Ca的提取率为90.24%、22.78%、61.61%、53.38%和84.2%。甲酸是甲醛氧化生产过程中的主要残留有机物；其浓度仅为 2.24 g/L。浸出过程的动力学数据服从混合控制动力学模型。浸出反应的表观活化能为0-30min为34.81 kJ/mol，30-150min为30.1 kJ/mol。