| Flotation is the most commonly used in the domestic and international Cu-Pb-Zn sulfide ore. In the flotation process, adding organic sulfhydryl compounds as trapping agent of sulfide mineral. Among the mercapto flotation reagent, Potassium n-butyl xanthate (PBX) is the most widely used. In addition to be sulfide mineral surface adsorption, the rest of the PBX will remain in the flotation wastewater, and make a large impact on the environment. In the meanwhile, 《Lead-zinc industry emission standards》 (GB25466-2010) implemented in 2012 has higher requirements to control the water pollution of Pb-Zn flotation wastewater.This thesis used ozonation methods to treat the PBX simulation wastewater and actual wastewater. It explored the influence of different ozonation conditions on the removal rate of PBX. The migration characteristics of Carbon and Sulfur in PBX simulation wastewater were studied. The products of ozonation were analyzed.In the meanwhile, the treatment efficiency of actual wastewater by ozonation was studied.Firstly, the experiment investigated the decomposition of 100 mg/L PBX simulation wastewater by different concentrations of ozone. The results demonstrated that:in different ozone concentrations, the removal rate of PBX could reach to 100%. The higher concentration of ozone output, removal rate of PBX was faster. However, the removal rate of COD and TOC were 50.9% and 28.5% respectively. It is shown that PBX can not be mineralized completely in the ozonation process, and generated small molecule organic matter which can be stable in water. The pH in simulation wastewater was decreased from 7.50 to 3.18.Secondly, the migration characteristics of Carbon and Sulfur in PBX during ozonation were analyzed by TOC analyzer, Ion Chromatography. The results showed that the distribution ratio of Carbon and Sulfur in gas and liquid phase system is not affected by concentration of ozone. When PBX was decomposed completely,71.5% of the Carbon and 79.4% of the Sulfur were determined in the liquid phase system,28.5% of the Carbon and 20.6% of the Sulfur were determined in gas phase system. The carbon and sulfur in liquid phase system is in form of TOC and SO42-, respectively. It can speculate that, at the beginning of the reaction, the ·HO2,·O2- and H+ are generated by indirect reaction of ozone in the wastewater. The·HO2 and·O2- are reacted with thiol preferentially and generate SO42-. The rest of H+ make the pH decrease.Thirdly, the ozonation products were determined by GC/MS and UPLC/MS. The results showed that the decomposition products of PBX (C4H9OCSSK) were SO42- and C4H9OH by ozonation. SO42-is generated from low-valent sulfur (<+6) which is the polar group of PBX. C4H9OH is generated from breaking C4H9-O-C of PBX. When the hydroxyl radical inhibitor (C4H10O) appears, the indirect reaction is inhibited and the decline of PH is not obvious.Finally, the comparison test of flotation wastewater and tailing reservoir wastewater by natural degradation and ozonation were discussed. The result showed that, ozonation is more effective than natural degradation of removing COD, and ozonation method save more time. The treatment effect of tailing reservoir wastewater by ozonation is more obvious. Appropriate optimization method can be used as the depth treatment of tailing reservoir wastewater. During the experiment, it is found that the SO42- of each unit operation wastewater (without slime wastewater) was increased after ozonation treatment. It is indicated that there are lots of low-valent sulfur (<+6) in the wastewater. |
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