海沙钛铁矿在硫酸溶液中的电化学溶解研究（英文）

An Electrochemical Dissolution Study of Ilmenite Fraction of Beach Sand in Sulphuric Acid Solution

采用电化学技术研究了孟加拉国海沙里钛铁矿在硫酸溶液中不同温度下的溶解行为.循环伏安研究表明,在没有添加碳粉的条件下钛铁矿的溶解非常困难.为探明钛铁矿的溶解过程,考察了钛铁矿-碳比例、硫酸浓度和温度对钛铁矿电化学溶解行为的影响.结果显示,钛铁矿在低还原电位和低温下的溶解速率较慢.施加更负的还原电位和在较高的温度下溶解速率加快.增加硫酸浓度(最大浓度达到1 mol·L^(-1))也可提高溶解速率,但在较高的硫酸浓度和还原电位下,由于氢气析出导致钛铁矿的溶解速率降低且气体吸附,最后使得钛铁矿的活性表面积减小.计算得到活化能数值在高温区间为50±10 kJ·mol^(-1),而低温区间为~15±5 kJ·mol^(-1),说明低温区间为扩散控制过程,而高温区间为化学控制过程.

Electrochemical techniques have been used to investigate the dissolution behaviors of ilmenite -action of beach sand of Bangladesh in sulfuric acid solutions at various temperatures. The cyclic voltammetric studies indicated that the dissolution of il- menite was very difficult without the addition of carbon powder in ilmenite. The effects of ilmenite-carbon ratio, acid concentration and temperature on cyclic voltammograrns have been investigated to understand the dissolution process of ilmenite. The investigat- ed results showed that the dissolution rate of ilmenite was slow at low applied reduction potentials and temperatures. However, the dissolution rate was accelerated at more negatively applied reduction potentials and higher temperatures. The dissolution rate was also increased with the increasing acid concentrations up to 1 mol. Ll. At larger acid concentrations and higher reduction potentials, the dissolution rate was decreased due to the starting of H2 gas evolution which eventually reduced the active surface area of pellet by adsorption. The activation energy was evaluated to be 50±10kJ·mol^-1 in the higher temperature region, while 15±5 kJ·mol^-1 in the lower temperature region, suggesting the diffusion controlled process at the lower temperature region and chemically controlled process at the higher temperature region.