高炉喷吹垃圾焚烧飞灰预处理工艺分析

为了解决高炉协同处置垃圾焚烧飞灰时氯负荷高的问题,以去离子水作为洗脱剂,通过考查不同水洗条件(水灰比、水洗时间、水洗温度、水洗次数)下垃圾焚烧飞灰中Cl元素和重金属元素的脱除效果,对飞灰高炉焚烧固化预处理中的工艺参数进行研究。结果表明,飞灰中Cl主要以NaCl、KCl、CaClOH的形式存在。在高炉协同处理前水洗预处理的适宜条件为水灰比为4 ml/g、水洗时间为5 min、水洗温度为25 ℃、水洗1次。在此条件下飞灰中Cl脱除率为86.45%、Zn脱除率为4.77%、Pb脱除率为35.65%、Cu脱除率为7.63%、Cr脱除率为9.71%。水洗后飞灰的配加比例、单位时间喷吹量、喷吹速度需按企业自身情况确定。在高炉喷煤比为139.12 kg/t(Fe)和飞灰喷吹量为喷煤量的1%条件下,由水洗后飞灰带入高炉的Cl质量为0.078 kg/t(Fe)、Zn为9.74×10-3 kg/t(Fe)、Pb为1.53×10-3 kg/t(Fe)、Cu为8.35×10-4 kg/t(Fe)、Cr为9.88×10-5 kg/t(Fe),远低于一般高炉熔炼要求,可以满足高炉正常运行需求。

Analysis on pretreatment process of municipal solid waste incineration fly ash injected in blast furnace

In order to solve the problem of high chlorine load in the coordinated disposal of municipal solid waste incineration (MSWI) fly ash by blast furnaces, the removal effects of Cl and heavy metal elements in fly ash under different washing conditions (such as water to ash weight ratio, water-washing frequency, temperature and time) and fly ash pretreatment process parameters in blast furnace were investigated using deionized water as eluent. The results show that chlorine in fly ash exists mainly in the form of NaCl, KCl and CaClOH. The suitable conditions for washing are as follows, water to ash weight ratio is 4 ml/g, water-washing time is 5 min, temperature is 25 ℃, and frequency is once. In this case, the dechlorination efficiency was 86.45% and removal rates of Zn, Pb, Cu and Cr were 4.77%, 35.65%, 7.63% and 9.71%, respectively. The proportion, injection volume per unit time and injection speed of fly ash after washing needed to be determined according to the enterprise′s own situation. According to the calculation of coal injection ratio of 139.12 kg/t(Fe) and fly ash injection amount of 1% for coal injection amount, the mass of Cl brought into blast furnace by fly ash after washing was 0.078 kg/t(Fe), mass of Zn was 9.74×10-3 kg/t(Fe), mass of Pb was 1.53×10-3 kg/t(Fe), mass of Cu was 8.35×10-4 kg/t(Fe), and mass of Cr was 9.88×10-5 kg/t(Fe), which was far lower than the requirement of general blast furnace smelting and could meet the operation need of blast furnace.