Analysis on pretreatment process of municipal solid waste incineration fly ash injected in blast furnace
PING Xiao-dong1, WANG Feng1,2, WANG Hai-feng3
1. State Key Laboratory for Advanced Iron and Steel Processes and Products, Central Iron and Steel Research Institute, Beijing 100081, China; 2. Research and Development Department, CISRI Sunward Technology Co., Ltd., Beijing 100081, China; 3. Department of Science andTechnology Development, China Iron and Steel Research Institute Group, Beijing 100081, China
Abstract: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.
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