Recycling Of Acidic Wastewater From Copper Smelting

Large amounts of acidic wastewater are produced in the copper smelter off-gas acid washing purification process, due to its high acidity, smelting enterprises generally referred to as "waste acid". The system of waste acid is very complex, composition and high concentration, it mainly contains a high concentration of sulfuric acid root ion, fluorine ion and chloride ion, at the same time also contains high concentrations of arsenic, a variety of metals such as copper, zinc, lead,cadmium, etc., it is a kind of wastewater that having serious harm and very difficult to treat in metallurgy industries. If the metallurgy industries treat the waste acid uneffectively, not only it will cause serious environmental pollution, but also causes the waste of resources. According to the characteristics of the waste acid, studying the treatment technology of recycling a variety of valuable elements in waste acid has important practical significance.For the shortage of high cost, waste of resource, produced large numbers of unwieldiness and hazardous solid waste, and water quality is difficult to meet the requirements of recycling by the methods of sulfide precipitation and iron salts, lime neutralization which are widely used in the treatment of copper smelting waste acid. Based on the train of thought of comprehensive utilization by enrichment method which recycling Arsenic trioxide by evaporation and concentration method,sulfurizing and precipitating metal in the dilute acid, recycling the dilute acid after removing the Fluorine, Chlorine in the concentrate of waste acid. In this paper, the author study the processing technology of the comprehensive utilization of the concentrate of waste acid in copper smelting based on the evaporation and concentration process that is purificating and recycling the copper smelting waste acid as the research object, studying the questions of removing fluorine,chlorine, arsenic and heavy metals, the main work and the main results as follows:(1)Study on the method of removing chloride in waste acid concentrate liquid by copper residue, the experiment investigates the influence factors of copper and copper oxide dosage, reaction temperature, reaction time, stirring speed on the removal efficiency of chlorine in waste acid concentrated liquid. The experimental results show that, when the copper and copper oxide dosage is more than 3 times of the stoichiometric quantities, reaction temperature is 20℃, reaction time is 1.5h, the stirring speed is 200r/min, the chlorine removal rate reached over 95%.(2)Study on the method of adsorbing fluoride in waste acid concentrate system by diatomaceous earth, the experiment investigates the influence factors diatomaceous earth dosage,reaction temperature, reaction time, stirring speed on the removal efficiency of fluoride in wasteacid concentrated liquid. The experimental results show that, when the diatomaceous earth dosage is more than 1.8 times the stoichiometric, reaction temperature is 60℃, reaction time is 10 h, the stirring speed is 200r/min, the fluoride removal rate reached over 90%.(3)In high acid condition,study on the removal effect of As and other heavy metals by sulfide precipitation in the waste acid concentrated liquid. The experiment investigates the influence factors sodium sulfide dosage, reaction temperature, reaction time, stirring speed on the removal efficiency of As and other heavy metals in waste acid concentrated liquid. The experimental results show that, when the sodium sulfide dosage is more than 4 times the stoichiometric, reaction temperature is 60℃, reaction time is 1h, the stirring speed is 150r/min, the removal rate of As, Cd, Cu, Fe, Pb and Zn can reach over 95%, 70%, 99%, 50%, 75%, 85%.