水泥窑共处置废物过程中重金属的流向分布

为了探索水泥窑共处置危险废物过程中重金属流向分布规律,研究了不同温度条件下Cr、As、Pb在煅烧熟料、颗粒物和尾气中的残留率.在900、1 000、1 100、1 200、1 300和1 450℃温度条件下,将添加Cr、As和Pb化学试剂的生料分别进行煅烧,模拟重金属在水泥窑内不同温度带的煅烧过程.结果表明,6个温度条件下,Cr主要分布在熟料中并且呈现不规则变化;颗粒物中的Cr在1 200℃条件下分布量最大,所占比例为32.79%(w);在900℃和1450℃条件下,烟气中的Cr分布量最大,所占比例为0.24%(w).6个温度条件下As主要分布在熟料中并且1 000~1 450℃条件下稳定在81%~83%之间;在900℃条件下,As在熟料中的残留率最大,所占比例为97%(w);在1450℃条件下,As在尾气中的分布达到最大值,所占比例为0.0023%(w).6个温度条件下,Pb在熟料中的残留率随着温度升高而逐渐减少,挥发颗粒物中的含量呈现相反的趋势;尾气中Pb的含量随着温度的升高逐渐增加.

Distribution of heavy metals during co-processing hazardous wastes in cement kilns

The distributions of heavy metals which contained in wastes and raw materials during co-processing of hazardous waste using cement kilns under different burning temperatures were studied. Cr, As, Pb chemical reagents were mixed with cement production raw materials, and then were burned under 900℃, 1 000℃, 1 100℃, 1 200℃, 1 300℃, 1 450℃, respectively, to simulate the co-processing wastes using cement kiln. Cr, As and Pb contents in clinker, particulate matter and exhaust under different burning temperatures were determined. The results showed that Cr was mainly distributed in the clinker under six temperatures. The distribution of Cr in volatile particulate matter was the largest at 1 200℃ and the proportion was 32.79%. While under 900℃ and 1 450℃, the distribution proportion of Cr in exhaust gas up to peak which both were 0.24%. As was also mainly distributed in the clinker at six temperatures and distribution rates were stable between 81% and 83%. At 900℃,the fixing rate of As in clinker was the largest which was 97%. At 1 450℃, the As concentration in the exhaust gas reached the maximum and the proportion was 0.0023%. The residual ratio of Pb in the clinker decreased gradually as the temperature rising. While the concentrations of Pb in volatile particles and exhaust gas showed an opposite trend.