Experiment And Application Research On The Recycling Technology Of Waste Acid In Nonferrous Metallurgy

The waste acid produced by acid making with gas in non-ferrous smelting industry were have large output and difficult to treat, and has been paid much more attention. This paper aiming at a Yunnan nonferrous smelting enterprise discharge waste acid that containing high arsenic and low pH value. Based on waste acid resourceful treatment, had study the vacuum evaporation experimental of waste acid. To investigate the effect of operating conditions on evaporation process and pollutant removal rate, the evaporation temperature, evaporation rate, degree of vacuum, stirring speed have been investigated. And the best operating conditions were obtained; the variation characteristics of heavy metals in crystallization have been explored. According to the experimental research results, combined with Yunnan nonferrous smelting industry status, proposed the new evaporation concentration processing, and the process design were performed on the evaporator.Experimental results show that:① the quality of concentrated solution is mainly affected by the evaporation rate in the process of evaporation of waste acid. The arsenic removal rate is more ideal in 6-7 concentration ratio, fluorine and chlorine removal rate in 6 better;② improve the evaporation temperature and the operation vacuum degree, is beneficial to the processing ability, and can reduce the concentrate of arsenic, fluorine and chlorine ion in the concentrated solution. Combined with the energy consumption and the concentrate quality requirements, advised to choose the vacuum degree in 0.06 MPa, and evaporating temperature is 125℃ for enrichment processing;③ the stirring speed also promoting to the removal rate of fluorine and chlorine, the stirring speed faster the better ability of removing fluorine chlorine. And enrichment process in a certain degree of stirring can increase the discharge of crystallization, stirring speed between 60 to 90 r/min crystallization effect is best;④ through the orthogonal experiment analysis, and combined with the corresponding cost control analysis, determine the optimum operating conditions in vacuum evaporating concentration of nonferrous smelting waste acid are that the evaporation temperature is 125℃,concentration ratio is 6, vacuum is 0.06MPa, stirring speed is 60 r/min.⑤ By XRD and XPS characterization analysis, the main heavy metals in waste acid in the form of As2O3, PbSO4, Cr2(SO4)3 deposited in the crystallization, and the heavy metals can be recovered by evaporation and crystallization.In order to recycle sulfuric acid and heavy metals resources, this paper aiming at the waste acid treatment scale of a nonferrous smelting enterprises in Yunnan Province, has carried on the design to the evaporation process, determine the processing technological process, evaporating of evaporation operation conditions, the type of evaporator, process calculation. Determine the heat transfer area, the structure size of the evaporator.The design scheme can effectively recover sulfuric acid and heavy metals, the project is economical and feasible, and can save and use energy, which provides a new method for the treatment of the waste acid of smelting enterprises.