Study On Removal Of Fluorine, Chlorine, Arsenic In Treatment Of Smelting Contaminated Acid By Evaporation Condensing Process

Copper smelting gas producing contaminated acid process produces large amounts of contaminated acid which contains high concentration of fluorine, chlorine, arsenic and copper, zinc, lead, cadmium and other metals. The sulfide precipitation and lime neutralization methods have widely been used at present. Those methods have some deficiencies as which produces a lot of hazardous and unwieldy solid wastes, spends huge processing cost, reuse difficultly the water after treatment. Along with the increasingly strict environmental protection and enterprise the need of construction of circular economy development mode, it is necessary to research the development of new resources comprehensive recovery characteristics of acid treatment process and technology.In this paper, according to the characteristics of this kind of contaminated acid, the method was based on evaporation concentration of the processing about its economic, efficient, recycling, the feasibility of integrated resources. Experimental evaporation and concentration of arsenic in the process of concrete was studied, and distribution of fluorine, chlorine, the removal of fluorine, chlorine on content in condensate are aim to lay the foundation for subsequent processing technology research.Evaporation concentration experiment explored the distribution characteristics of fluorine, chlorine, sulfate radical, arsenic in condensate and in concentrate and the crystallization removal rates of arsenic trioxide in concentrate at different heating temperatures and different enrichment ratios. The results showed arsenic, fluorine and chloride have good removal rates from contaminated acid by evaporation condensing process. Heating temperature at130℃, enrichment ratios in6-7, the removal rate of arsenic, fluorine and chlorine reached72%,88%,77%, beside, the concentration of sulfate radical in concentrate reached336483mg/L.From the process of evaporation concentration, the concentration ranges of fluorine, chlorine in concentrate were respectively2000-4200mg/L,390-580mg/L. Lime precipitation-lime aluminium salt processing of the fluorine and chlorine ion in condensate were used. For defluorination, the calcium fluoride ratios, pH, reaction time, sedimentation time and the quantities of PAM were studied especially. The results showed the effects were good. In11.0<pH<12.0, the mole ratio of calcium and fluoride in1.5:1, mixed reaction time in40min, sedimentation time in120min and the quantity of PAM about3mg/L, the concentration of the fluorine ions in wastewater could be reduced to20mg/L and the removal rate could reach more than99%. Through the orthogonal experiment, the results indicated the factors which affect the effects of removing fluorine ion order as:the mole ratio of calcium and fluoride>pH>reaction time> the quantity of PAM.For dechlorination, the calcium and aluminum and chloride ratios, pH, reaction time and temperature were studied especially. The results showed the effects were good. In12.8<pH<13.0, the mole ratio of calcium and aluminum and chloride in10:4:1, mixed reaction time in120min, the temperature in25℃, the concentration of the chloride ions in condensate could be reduced to220mg/L and the removal rate could reach more than70%. Through the orthogonal experiment, the results indicated the factors which affect the effects of removing chloride ion order as:the mole ratio of calcium and aluminum and chloride>pH>temperature>reaction time.