氯化剂对铁尾矿焙烧过程中重金属挥发的影响

针对铁尾矿中的重金属，采用氯化焙烧方法进行分离.考察了不同氯化剂（CaCl₂、NaCl和AlCl₃·6H₂O）在不同温度下对铁尾矿中重金属（Cr、Ni、Pb、Zn、Cu）挥发率的影响.结果表明：添加AlCl₃·6H₂O作为氯化剂时，由于其在135℃时过早分解，在1000℃时重金属的最高挥发率均在30%以下.添加NaCl可使重金属Pb、Zn、Cu的挥发率达到90%以上，但Cr和Ni的挥发率分别只有16.2%和30.0%.CaCl₂与NaCl、AlCl₃·6H₂O相比具有最好的去除效果，在900℃的焙烧温度下，能够去除大部分的Pb（97.5%）、Zn（99.0%）和Cu（93.3%），且Ni、Cr在1000℃时最大挥发率分别为31.9%和49.5%.此外，浸出实验表明，焙烧渣中Cr、Ni、Pb、Zn、Cu浸出浓度均低于GB16889-2008相关限值要求.

Effect of chlorine on the volatilization of heavy metals by roasting iron tailings

A chlorination roasting method was used for separating heavy metalsfrom iron tailings. The influence of chloride (i.e. CaCl₂, NaCl and AlCl₃?6H₂O), content of chloride, and temperatures on the volatilization of heavy metals was studied. Experimental results showedthat when usingAlCl₃?6H₂O as chloride, the volatilization ratios of heavy metals was lower than 30%, due to the prior decomposition of AlCl₃?6H₂O at 135℃. With the addition of NaCl, the volatilization ratios of Pb, Zn, Cuachieved above 90%, but only 16.2% of Cr and30.0% of Ni were removed from tailings. The addition of CaCl₂ exhibitedthe best volatilization effect compared to NaCl and AlCl₃?6H₂O.The hazardous Pb, Zn and Cu were reduced significantly (97.5% of Pb, 99.0% of Zn, 93.3% of Cu) at 900℃, and the maximum volatilization of Ni and Cr was 31.9% and 49.5% at 1000℃. Moreover, the leaching experiment showed the leaching concentration of Cr, Ni, Pb, Zn, Cu in roasted residue could meet the regulatory limit of leachate (GB16889-2008).