| Summary: | 碩士 === 崑山科技大學 === 環境工程研究所 === 97 === The sludge from the wastewater treatment process in the electroplating plant contains high level of hazardous metals. It will result serious pollution of soil and groundwater if the sludge is discarded without any
treatment. The object of this study is recovery useful metals from the sludge generated in a chemical Zn-plating process by vitrification. The Zn-plating sludge was mixed with dolomite, limestone, and cullet, and heated to 1400 oC for melting. The molten material was separated into slag
and ingot due to the density of the metal species. In addition, the metals with low boiling point was vaporized into flue gas and concentrated in the fly ash. The high level of Zn made the fly ash deserve to be recovered.
The main composition of sludge is Fe and Zn. For the contribution of input materials, Mg, Ca, and Si are provided by dolomite, limestone, and cullet, respectively. For output material, the major composition of slag and
ingot is Fe. The main constituents of particulate phase in flue gas are Cd and Zn. The slag was tested by toxicity characteristics leaching procedure to check its chemical stablility. The leaching concentration was all below
the standard limits and the slag can be recovered as building materials. Before vitrification, the level of Fe and Zn was 21.0% and 9.3%,respectively. After vitrification, the concentration of Zn was reduced to
1,000 mg/kg and 99.9% of Zn was vaporized into flue gas. In a real scale plant, the Zn in the flue gas can be recovered by air pollution control device. For ingot, the level of Fe was 66 %, and it can be used as the raw material
for steel making. Overall speaking, the vitrification technology can stabilize the sludge, and recover Fe and Zn, and achieve the goal of transforming waste into resource.
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