Removal of Organohalogen Compounds and Recovery of Heavy Metals from Municipal Solid Waste Incineration Fly Ash by Column Flotation

建立了一套柱浮选装置，并开发了柱浮选技术，通过分离垃圾焚烧飞灰中富含有机卤素化合物的未燃碳（UC），去除飞灰中的有机卤素化合物，回收飞灰中的重金属。详细研究了各影响因素对UC去除率的影响。在不同浮选柱条件下进行了UC和有机卤素化合物的去除试验，为确定垃圾焚烧飞灰中有机卤素化合物的最佳浮选柱条件提供了重要参考。主要研究结果如下：1）物理化学影响因素：气体流量、分布器比表面积、pH值、捕收剂和助捕剂、UC粒径对垃圾焚烧飞灰中UC和有机卤素化合物的去除效果有重要影响。2）通过考察多种物理和化学影响因素对UC和有机卤素化合物去除效果的影响，最佳浮选条件为：加入HLB=13.5的混合表面活性剂，煤油浓度为3.0%（体积分数）将聚氧乙烯（20）失水山梨醇单油酸酯与失水山梨醇单油酸酯混合制成煤油混合物，然后将4.0ml/L的煤油混合物加入到料浆中，料浆中MIBC=53.3μl/L，pH=5.9，采用4#多孔板分布器，气体流速：0.0534m/s;两次浮选，第一次30 min，第二次40 min（条件D）3）在最佳浮选条件下，UC和PCDD/Fs的去除率分别为64.0%和41.9%，4）除Na、K、Ca和Zn向溶液中的迁移率较高外，其余金属大部分留在残渣部分。

The authors have set up a column flotation equipment and developed the technique of column flotation to remove organohalogen compounds and recover heavy metals from MSWI fly ash by separating the organohalogen compounds-enriched unburned carbon (UC) from MSWI fly ash. The effects of influential factors on the UC removal efficiency have been studied in detail. UC and organohalogen compounds removal experiments under different column flotation conditions were carried out, which provides an important reference for setting up the optimum column flotation condition for organohalogen compounds removal from MSWI fly ash. The main results are summarized as follows :1) The physical and chemical influential factors : gas flow rate, sparger surface area, pH, collector and collect assistant, UC particle size have important effects on the removal efficiencies of UC and organohalogen compounds from MSWI fly ash.2) By investigating the effects of many physical and chemical influence factors on the removal efficiencies of UC and organohalogen compounds, the authors obtained the optimum flotation conditions : adding the surfactant mixture (HLB=13.5, Concentration in kerosene=3.0 Vol.%) of polyoxyethylene (20) sorbitan mono-oleate and sorbitan mono-oleate into the kerosene to make kerosene mixture, then adding 4.0ml/L-slurry kerosene mixture into the slurry ; MIBC=53.3μl/L in the slurry, pH=5.9 ; using 4# porous plate sparger, gas flow rate : 0.0534m/s; twice flotation, first time 30 minutes, second time 40 minutes (condition D).3) Under the optimum flotation condition, 64.0% of UC and 41.9% of PCDD/Fs, 40.8% of coplanar PCBs and 44.1% of PCBs were removed from MSWI fly ash.4) Most of other metals are left in the residue part, except that the transference ratios of Na, K, Ca and Zn to solution are high.