Research On The Removal Of Lead And Chromium Ion In The Simulated Flotation Wastewater Of Nonferrous Metals Treated By Pyrrhotit

This subject is launched to resolve the questions of large quantity of sludge, difficulty of Solid-Liquid Separation and no reutilization in the application of mineral in the treatment of nonferrous metals flotation wastewater. Pyrrhotite was used as the primary material and wastewater was simulated in this experiment. The properties and mechanism were studied systematically in the application of pyrrhotite in the treatment of lead ion and Cr⁶⁺ in the nonferrous metals flotation wastewater in this experiment.The influencing factors of the disposal of lead ion in the nonferrous metals flotation wastewater treated by pyrrhotite was studied in the experiment, the results indicated: (1) The native pyrrhotite could reduce pH value and remove lead ion simultaneously and was suited to treat alkaline wastewater with high concentration of lead, and the characteristics of high processing speed was also showed in the experiment. The dosage of mineral should accord to the pH value of wastewater. Minerals with small grain sizes and residual organic pharmacy was beneficial to treat the wastewater. Interferential electrolyte Ca²⁺ showed little effect to the removal of lead ion. (2) The best roasting conditions for the pyrrhotite was as follows: the calcination temperature was 400℃, the calcinations time was 50min, the grain sizes of minerals was 61μm～74μm. (3) The minerals under the best roasting conditions had better capacity than native pyrrhotite in the treatment of nonferrous metals flotation wastewater. The trend of treatment effect caused by influencing factors of roasted minerals was similar to that of native pyrrhotite.The influencing factors of the disposal of Cr⁶⁺ in the nonferrous metals flotation wastewater treated by pyrrhotite was studied in the experiment, the results indicated: (1) Alkaline wastewater contained Cr⁶⁺ could be treated directly by native pyrrhotite, but acidic conditions was more beneficial for the treatment. Pyrrhotite had high processing speed to Cr⁶⁺, the removal rate of Cr⁶⁺ increased with the increasing of the dosage of mineral and the diminishing of grain sizes of minerals. Residual organic pharmacy and a certain concentration of Ca²⁺ were beneficial for removal of Cr⁶⁺.(2) The best roasting conditions for the pyrrhotite was as follows: the calcination temperature was 400℃, the calcinations time was 50min, the grain sizes of minerals was 61μm～74μm. (3) The minerals under the best roasting conditions had better capacity than native pyrrhotite in the treatment of nonferrous metals flotation wastewater. The trend of treatment effect caused by influencing factors of roasted minerals was similar to that of native pyrrhotite.Reuse experimentation of pyrrhotite was operated, the results indicated: (1) both of native pyrrhotite and roasted minerals had the advantages of low loss rate and good reuse value. (2) Compared to bentonite, pyrrhotite could flocculate suspended solids which bring a speedy Solid-Liquid separation. Pyrrhotite also had the advantages of less sludge and low-cost for the treatment of sludge.The results of XRD, XRF and analyse of experimental phenomenon indicated: some intermediate products such as FeSO₄,Fe₃O₄ was produced when the calcination temperature was 400℃and the calcinations time was 50min. This was the main reason of the markedly improving of treatment capacity for pyrrhotite. Poriferous surface of roasted minerals was also one reason of the improving of treatment capacity for it.