拜尔法赤泥精细还原实验研究
doi: 10.13205/j.hjgc.201501024
THERMAL DESORPTION EXPERIMENT OF POLYCYCLIC AROMATIC HYDROCARBONS CONTAMINATED SOIL USED AS CEMENT RAW MEAL
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摘要: 用精细还原方法对拜尔法赤泥进行了处理,以铁氧化物的还原度为考察指标,取其影响因素及变化范围为:赤泥颗粒平均尺度1.24~2.43μm、气态还原剂CO-H2、还原温度700~1 000℃、还原时间2~4 h。研究结果表明,还原温度对还原度的影响最为显著,其他因素影响不显著;最佳还原工况为:还原温度1 000℃、赤泥颗粒平均尺度1.236μm、气态还原剂为H2,还原时间4 h;在最佳工况条件下进行还原,还原度高达99%以上;精细还原过程中赤泥颗粒间未发生烧结,有利于采用物理方法将铁元素与其他杂质元素进一步分离;分离铁以后的尾渣可用于炼钢用脱硫渣。Abstract: Taking polluted soil surrounding a Shougang coking workshop as sample object,TG analysis,and thermal analysis on raw soil and cement raw mill experiments were conducted,the results showed that: The polluted soil contained various organic pollutants of PAHs,and the total concentration of PAHs was about 156. 39 mg /kg. Weight loss of the soil contaminated by PAHs could be divided into three stages at 850 ℃: Water losing stage,organic matter decomposition stage, and inorganic carbonate decomposition stage. With the increase of heating temperature,removal rate of total PAHs in raw soil went up. Using polluted soil as cement siliceous raw material,except naphthalene,acenaphthene,two hydrogen acenaphthene and anthracene,other organic compounds of PAHs had residues at 300 ℃ and small amounts of phenanthrene had residue at 600 ℃,showing that cement raw material had certain adsorption on PAHs pollutants. Therefore,when polluted soil of PAHs was coprocessed into the cement kiln,the content of pollutants in flue gas volatilization should be focused on.
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Key words:
- polluted soil /
- polycyclic aromatic hydrocarbon ( PAHs) /
- raw meal
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