焚烧飞灰水泥窑共处置过程Pb的迁移模型

Modeling of lead migration in MSWI fly ash during the co-processing with cement kiln

以焚烧飞灰替代水泥原料,开展熟料煅烧实验,通过水泥回转窑系统中Pb的简化质量平衡模型,研究替代生料比例分别为1%、5%、10%和20%时,窑灰循环对Pb固定和迁移的影响.根据工业水泥窑Pb的监测数据,分析Pb和Cl输入总量对Pb迁移的影响.模型计算表明,飞灰替代原料导致窑灰和熟料中Pb的质量分数显著增加,当替代比为10%时,窑灰和熟料中Pb的质量分数由114.9 mg/kg和21.1mg/kg分别增至1 125.6 mg/kg和206.7 mg/kg.窑灰循环也对Pb的迁移影响显著,当替代比为1%,窑灰循环率为0.4时,3 h内窑灰和熟料中Pb的质量分数增至200 mg/kg和39.3 mg/kg,而后渐缓直至稳定.窑灰循环率从0.4增加到1,在最终稳定状态时,熟料中Pb的质量分数为90.22 mg/kg,现场试验熟料中Pb的质量分数为82 mg/kg,理论计算与实际检测基本吻合.

The fly ash of municipal solid waste incinerator （MSWI） was added to the cement raw meal to produce clinkers on a lab scale and a real scale. The monitoring data of Pb in the cement kiln, which co-processed waste materials, were statistically analyzed to clarify the effect of total Pb or chloride input on Pb migration. A simplified mass balance model of Pb in the cement kiln was built to investigate the effect of kiln dust circulation on the migration characteristics of Pb when the substitution ratios of MSWI fly ash to cement raw meal were 1%, 5%, 10% and 20%, respectively. The results of the calculation model show that the Pb concentration in kiln dust and clinker increased quickly from 114.9 mg/kg and 21.1 mg/kg to 1 125.6 mg/kg and 206.7 mg/kg respectively at the substitution ratio of 10%. Furthermore, the kiln dust circulation had a significant effect on the Pb concentration in kiln dust and clinker, which increased quickly to 200 mg/kg and 39.3 mg/kg at the initial 3 h and subsequently decreased slowly at the substitution ratio of 1% and at a kiln dust circulation ratio of 0. 4. The Pb concentration in clinker increased to a large degree during the final stabilization stage when the kiln dustcirculation rate increased from 0.4 to 1. The calculated and tested Pb concentration in clinker was 90.22 mg/kg and 82 mg/kg, respectively, which shows the calculation model is accurate.