焦化废水还原浸出软锰矿动力学

Leaching kinetics of pyrolusite ores using coking wastewater as reductant

以焦化废水为还原剂,在硫酸介质中利用收缩芯模型研究焦化废水加压直接还原浸出软锰矿的动力学,考察搅拌速度、反应温度、软锰矿粒径、硫酸浓度和焦化废水CODcr浓度对锰浸出速率的影响。结果表明:锰浸出率随反应温度、硫酸浓度、焦化废水CODcr浓度的增加和软锰矿粒径的减小而增大。在393 K^423 K间,焦化废水还原浸出软锰矿受固膜扩散控制,表观活化能为15.2 kJ/mol,硫酸和焦化废水CODcr浓度的表观响应级数分别为1.21和0.98。机理分析表明:软锰矿氧化焦化废水中大分子有机物分解成小分子而被还原溶出,或被小分子直接还原溶出;反应过程中,软锰矿表面残留的Fe、Si、Al形成孔洞薄壁而影响锰的溶出过程。

Using the coking wastewater as reducing agent to pressure leaching the pyolusite, the shrinking core model was used to investigate the kinetics of the manganese reductive leaching process in the sulfuric acid solution. The effects of stirring speed, reaction temperature, the particle size of the pyrolusite and the concentrations of H_2SO_4 and coking wastewater on the leaching rate were investigated. The results show that the leaching of manganese increases with the increase of the temperature, the concentrations of H_2SO_4 and coking wastewater, whereas decreases with the increase of particle size. The kinetic equation for the manganese pressure reduction is presented at the temperature ranging from 393 K to 423 K, with the apparent activation energy of the leaching process is obtained to be 15.2 kJ/mol and the reaction orders for the concentration of H_2SO_4 and coking wastewater are 1.21 and 0.98, respectively. It suggests that the reduction of manganese from pyrolusite is controlled by the diffusion through the ash-inert layer. The mechanism analysis shows that pyrolusite is reduced by the multikey macromolecules of coking wastewater through providing the oxygen atom for the macromolecular organic compounds decomposition, or is reduced directly by small organic molecules. The thin-walled with holes superficial layer constituted by residual of Fe, Si, Al affects the Mn leaching.