都市垃圾焚化飛灰中含有高量的可溶解性鹽類(如氯鹽、鈉鹽…)，且重金屬有溶出之疑慮，進而影響其再資源化發展。因此，去除鹽類的水萃程序為前處理最常用的方法之一。水萃可去除溶解性鹽類，同時也將大量的重金屬鉛和其他重金屬帶到水萃液中，使得水萃液中含大量重金屬。根據文獻，坡縷石是一種多孔性的天然黏土礦物，具有高吸附量的優點，且濕式研磨對焚化飛灰有穩定重金屬的效果，因此本研究以坡縷石吸附飛灰水萃液之重金屬，並引進機械化學濕式研磨技術，使重金屬達到穩定不易溶出的效果，製造出無害化的原料。 研究分為兩部份，第一部份：坡縷石吸附重金屬能力之研究，解決水萃廢水中重金屬含量的問題，以實際水萃程序所產生之水萃液，探討坡縷石在此環境中對重金屬的吸附能力。第二部份：研磨對水萃灰加吸附後坡縷石的穩定效果探討，解決水萃灰和吸附後坡縷石重金屬溶出的問題，在水萃灰與吸附後坡縷石混合的情況下，探討機械化學對重金屬穩定的影響，最後應用序列萃取(Sequential Extraction Procedure)討論各種重金屬研磨後之穩定特性。 由實驗結果得知，添加3 g改性後的坡縷石能有效的將100 ml的水萃液中重金屬吸附處理到符合放流水標準。將水萃灰與吸附重金屬的坡縷石以乾重比10：3混合並進行研磨，研磨能有效減少混合灰粉體粒徑至2.5 μm，且對混合灰中重金屬具有穩定的作用，使用研磨2小時即可抑制鉛、鋅的TCLP溶出，分別從1.18與0.66 mg/L降至0.03與0.01 mg/L；序列萃取結果也顯示研磨之後，重金屬鉛、鋅、銅、鎘，皆傾向形成較穩定的重金屬型態，顯示濕式研磨對水萃灰與坡縷石兩種材料混合一樣能有效降低其重金屬溶出，將重金屬穩定在粉體中。 Municipal solid waste incinerator (MSWI) fly ash contains a large amount of solubility of salts (ex: chloride, sodium …), and easily dissolved heavy metals that can affect its recycling. Therefore, the water extraction was usually used to remove the salts as the pretreatment process for fly ash recycling. Pb and other heavy metals would be removed into the water extraction solution at the same time. The waste water from water extraction could contain a large number of the heavy metals. Many studies indicate that palygorskite is porous natural clay minerals and have the advantage of adsorption. The wet milling process can stabilize the heavy metals of MSWI fly ash. In this study, palygorskite was used to adsorb the heavy metals of extracted water and then the wet milling process was used to stabilize the heavy metals in the milled mixture of the fly ash and the adsorbed palygorskite. Finally, a non-hazardous mater will be made after the processes.
This study consists of two parts: first one, discussing palygorskite adsorption capacity of heavy metals to solve the problem of the heavy metal of extracted solution. Second one, the wet milling was used to investigate the stabilization effect on water extracted fly ash and adsorbed Palygorskite.
The results of the experiment show that add 3g of modified palygorskite was able to effectively treat heavy metals to meet the effluent standards for water-extraction solution of 100ml. The extracted fly ash and adsorbed Palygorskite mixed and milled by the dry weight ratio 10:3. Milling can effectively reduce the mixed ash of the particle size D50 to 2.5 μm and stabilized the heavy metals in the mixed ash. The milling can restrain the leaching of Pb and Zn of TCLP after 2 hours extraction. The TCLP concentration of Pb and Zn were decreased from 1.18 and 0.66 mg/L to 0.03 and 0.01 mg/L. The results of sequential extraction procedure (SEP) shows that the heavy metals of Pb, Zn, Cu, Cd were tend to form more stable species after milling.