中文摘要：

铬渣是毒性较强的危险废物,通过实验室模拟化学还原处理技术,以亚硫酸钠为还原剂,将铬渣中毒性强的六价铬（Cr（VI））还原转化为低毒的三价铬（Cr（III））,考察不同的反应时间和亚硫酸钠用量对铬渣中六价铬去除效果的影响.结果表明：亚硫酸钠可以有效去除铬渣中的六价铬,当亚硫酸钠与六价铬的计量比为理论计量比的12倍、修复时间为15d以上时,总铬浸出浓度去除率最高（78%）;继续延长反应时间或增加亚硫酸钠用量均不能有效提高去除率.随后加入磷酸钠作为稳定剂稳定解毒后的铬渣,当磷酸钠与三价铬的摩尔比为4∶1时,总铬浸出浓度为6.9mg/L,低于危险废物鉴别标准GB 5085.3—2007中规定的总铬浸出浓度限值15mg/L,并生成稳定的CrPO_4·6H_2O晶体.此外,亚硫酸钠与磷酸钠分步加入（两步法）处理铬渣的效果好于两者同时加入（一步法）的效果.

英文摘要：

Chromite ore processing residue （COPR） is one of the most hazardous residues. Batch experiments were conducted to evaluate the feasibility of the remediation of Cr（Ⅵ） in COPR by the reductant sodium sulfite （Na2SO3）. Different reaction time and Na2SO3 dosages were investigated to evaluate the efficiency of Cr（Ⅵ） reduction. The results indicated that Na2SO3 could effectively remove Cr（Ⅵ） from COPR. When adding Na2SO3 at a dosage of 12 the stoichiometric requirement and maintaining the treatment time over 15 days,78% of total Cr in leachate was removed; further increases of Na2SO3 dosage and/or treatment time had little effect on the removal of total Cr in leachate. Afterwards, sodium phosphate （ Na3PO4 ） was added to immobilize the Cr （III）-containing compounds in COPR. When the molar ratio of Na3PO4 to Cr（Ⅲ） was 4：1 ,the total Cr in leachate was 6. 9mg/L,which was much lower than the limit concentration （≤ 15mg/L） in China Hazardous Waste Identification Criteria （GB 5085.3--2007）. Moreover, crystalline CrPO4 · 6H2O was observed after Na3 PO4 was added as an immobilizer. In addition ,the two-step treatment （i. e. , Na2SO3 and Na3PO4 were sequentially added into the COPR） was more beneficial to remove Cr （Ⅵ） than the one-step treatment （i. e. ,Na2SO3 and Na3PO4 were simultaneously added）.