垃圾焚烧飞灰中氯元素存在形态及深度脱氯的研究

垃圾焚烧飞灰中的氯含量影响其在水泥窑协同处置生料中的占比,因此需要对飞灰做脱氯处理。利用XRD对飞灰氯元素的存在形态研究表明：氯元素以水溶性氯和非水溶性氯2种形态存在于飞灰中,炉排炉飞灰的水溶性氯化物为CaCl₂·Ca（OH）₂·H₂O、CaClOH、CaCl₂·2H₂O、KCl和NaCl,非水溶性氯化物为AlOCl和Ca₁₀（Si₂O₇）₂（SiO₄）Cl₂（OH）₂等;流化床飞灰的水溶性氯以CaCl₂·2H₂O和KCl形式存在,非水溶性氯以AlOCl、Ca₁₀（Si₂O₇）₂（SiO₄）Cl₂（OH）₂和Ca₄OCl₆等形式存在。对水洗脱除水溶性氯的研究结果显示：对于炉排炉飞灰,控制液固比（mL/g,下同）为10+4+2、3次常温水洗,水溶性氯脱除率达97.01%;对于流化床飞灰,控制液固比组合6+6+4、3次常温水洗,水溶性氯脱除率达99.17%;酸、碱洗及高温煅烧均能降低飞灰非水溶性氯含量,其中煅烧处理后的炉排炉飞灰残氯质量分数为0.36%、流化床飞灰为0.45%。

Study on existing speciation and deep dechlorination of chlorine in waste incineration fly ash

The chlorine content of fly ash in waste incineration affects its proportion in the cement kiln co-treatment of raw materials,so fly ash needs to be dechlorinated.XRD was used to study the existing speciation of elemental chlorine,which showed that chlorine existed in fly ash in two forms of water-soluble chlorine and water-insoluble chlorine.The water-soluble chlornde in fly ash of grate furnace were CaCl₂·Ca（OH）₂·H₂O,CaCl₂·2H₂O,CaClOH,KCl and NaCl,and the water-insoluble chlorine were Ca₁₀（Si₂O₇）₂（SiO₄）Cl₂（OH）₂ and AlOCl,etc. The water-soluble chlorine in fly ash of fluid-bed existed in the forms of CaCl₂·2H₂O and KCl and the water-insoluble chlorine existed in the forms of AlOCl,Ca₁₀（Si₂O₇）₂（SiO₄）Cl₂（OH）₂ and Ca₄OCl₆ and so on.The experimental results of water elution to remove water-soluble chlorine showed：for the fly ash of grate furnace,under the conditions of 10+4+2 of liquid-solid ratio（mL/g） and washing for three times at room temperature, the water-soluble chlorine removal rate could reach 97.01%;for the fly ash of fluid-bed,under the conditions of 6+6+4 of liquid-solid ratio and washing for three times at room temperature,the removal rate of water-soluble chlorine could reach 99.17%.Washing with acid and alkaline,high-temperature calcination could reduce the water-insoluble chlorine content of fly ash.The residual chlorine content of fly ash of grate furnace and the fly ash of fluid-bed after calcination were 0.36% and 0.45% respectively.