| With the substantial increase of electrolytic aluminum production, the spent pot lining generated from aluminum electrolysis cell are also increased year by year. The spent pot lining are hazardous solid waste which contain a lot of soluble fluoride, and cause serious pollution on the surrounding environment when the spent pot lining are open dumpped or direct landfilled. Meanwhile, the fluorides have a serious impact on the flotation processes. Therefore leaching followed by the flotation process are proposed to remove the soluble fluoride, making hazardous solid waste into general solids, to optimize the flotation processes. Therefore, the study of the F- migration in the disposal processes of the spent pot lining have important theoretical and practical value.The new raw materials in this text are waste cathode materials of electrolytic aluminum reduction cell which are taken from electrolytic aluminum manufacturer in Yuncheng, Shan xi province. Its main component were fully studied by mineralogical analysis, XRD and elemental analysis to analyze the existence forms of fluoride. Through coarse crushing, fine crushing and leaching, the optimal leaching experimental conditions were studied, and meanwhile the fluoride waste were conducted with innocent treatments. After leaching, the leaching residue can be discharged directly as non-hazardous solid waste, and also sorted through the flotation process, to recycle the flotation concentrate ultimately.Through the experimental research, the main conclusions are as followed:(1)The constituents of the spent pot lining are mainly C, Na3AlF6, NaF, CaF2, in which the carbon content is up to 68.58% and others are the electrolyte. The fluoride are mainly Na3AlF6, CaF2, NaF, and Na F is the main soluble fluoride at room temperature.(2)The optimum leaching conditions of the experiment are: The maximum leaching rate of soluble F- is 11.25% which occupy 97.8% of the theoretical soluble F-, with water as the leaching agent, particle size of 0.075~0.096 mm, liquid to solid ratio of 55: 1, leaching temperature of 85 ? and 2h leaching time.(3)The XRD analysis of leaching residue showed: The NaF in waste cathode was almost completely dissolved into the solution. The F- in the leaching residue can be controlled within the limit content of hazardous solid waste, which can be discharged or recycled by flotation process.(4)The experimental results of high concentration fluorine-containing waste water processes showed that: the CaCl2 precipitation and aluminum sulfate precipitation methods can drop soluble F- concentration to 10mg/L or less to meet the national wastewater discharge standards, and the highest removal rate of soluble F- is 99.5%. The former final solution is neutral, and the latter is acidic. The CaO precipitation and ultrafiltration are unable to meet the standards. Comprehensive comparison, the CaCl2 precipitation is the best dispose experimental method for the fluorine-containing waste water treatment.(5)Put appropriate addition into original cathode to recycle the concentrate after flotation. The results showed that: After calcination by adding 20% bitumen and appropriate flotation concentrates in original cathode, the resistivity significantly increased, and can reach the using standard. At the same time, the flotation concentrate can't be too much, otherwise result in resistivity outside the specified range.The results have reference value for the storage, transportation, purification and waste water treatment. |
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