不同碱度下不锈钢渣中铬的迁移及富集行为

Migrant and enrichment behavior of chromium in stainless steel slag at different basicities

铬元素的赋存状态对不锈钢渣中铬的稳定性有重要的影响,而尖晶石相被认为是最佳的铬稳定相。为有效稳定不锈钢渣中的铬元素,降低铬的溶出性,减少污染的风险,研究了不同碱度条件下铬的迁移及富集行为。试验过程中所用的合成渣在1 600℃条件下充分熔化后,然后分别在1 600℃和1 300℃下保温30min后进行水冷,并采用SEM-EDS及XRD观察不同碱度下不锈钢渣的物相组成和铬的赋存形式。结果表明:碱度能显著影响铬的迁移及富集行为,试验中碱度为1.5时,有利于不锈钢渣中的铬富集于尖晶石相,在1 300℃条件下,铬的富集度接近100%。碱度为1.0时,铬主要溶解于液相中,1 300℃条件下冷却只有少量的含铬尖晶石相生成。当碱度为2.0时,有含铬的方镁石相析出。同时低温条件下淬冷有利于不锈钢渣中的铬向尖晶石相富集。

The existential state of chromium has a great influence on stability of chromium in stainless steel slag,and spinel phase is considered to be the optimal stable phase for preventing the chromium from leaching.In order to effectively stabilize chromium element in stainless steel slag and reduce the leaching of chromium to decrease the risk of pollution,in the present work,the effect of slag basicity on the migration behavior and existential state of chromium was investigated in the experiment.The samples were heated for 30 min at 1 600℃for completely melting and soaking for 30 min at 1 600 ℃and 1 300 ℃ before quickly quenched in water.The microstructure and existential state of chromium were determined by scanning electron microscope-energy dispersive spectroscopy（SEM-EDS）and Xray powder diffraction（XRD）.The results showed that the basicity significantly influenced the migrant and enrichment behavior of chromium in stainless steel slag.It was beneficial for chromium enriching in spinel phase with w（CaO）/w（SiO2）ratio of 1.5,especially at 1 300 ℃,the enrichment degree of chromium was nearly up to 100%.When the basicity was 1.0,the solubility of chromium in the liquid phase was relatively high,and only minor amount of spinel phase could be formed at 1300 ℃.As the basicity increased to 2.0,the chromium-bearing periclase phase was precipitated.