| Summary: | 碩士 === 淡江大學 === 水資源及環境工程學系碩士班 === 99 === Municipal solid waste incinerator (MSWI) fly ash with high alkalinity, high chloride and heavy metals problems. The chlorine and heavy metal will form easily dissolved salts in fly ash. In this study, the water extraction procedure as a pre-treatment to remove plenty of chlorine salts. Then stability of heavy metals with wet ball milling technology. The study is to investigate heavy metal stabilization efficiency and mechanism during the wet ball milling for MSWI fly ash. And adding a known concentration of lead fluid in experimental. Observed the lead by mechano-chemical of change. According to the results of water-extracted fly ash leaching of heavy metals, the lead of the leached concentration was 9.76 mg/L. It was higher than with the USEPA regulatory limit of 5mg/L. Therefore, the future tendency is to discuss Pb stabilization by milling.
According to the experimental results, stabilizing effect of lead using the mixing ratio of milling media 1:1(diameter of milling media is 1 and 5 mm respectively) is better than a single small diameter 1mm milling media. However, the mutual milling of the water-extracted fly ash and concentration 10g/L、40g/L lead fluid was 8 hours and then extractable lead by TCLP. The results show that 93%、82% of lead stabilization efficiency respectively. The water-extracted fly ash and concentration 40g/L lead fluid milled 0-20 hours. The results by XRD analysis showed with the long milled of the lead crystalline particles were hardly to identify. The observation of SEM indicates that milled fly ash to from solid solution which led the lead into fly ash to result in stabilization. According to mathematical projections, mechano-chemical treatment can increase 37-40% stabilization efficiency of heavy metals. Chemical reaction to form a stable compound that only 12% stabilization efficiency of heavy metals. The lead to form a stable adsorption can increase 18% stabilization efficiency of heavy metals. Finally, the results by XRD analysis showed the lead milled 8 hours. The predominant species of lead was identified to be Pb7O6Cl2 into insoluble state PbO2. Confirmed that mechano-chemical treatment can effectively inhibited the elution of lead from fly ash.
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