Study On Treatment Of Waste Acid In Copper Smelting By Ferric Oxide

Copper smelting waste acid is one of the difficult pollutants in the copper smelting industry.Because of its large output and complex composition,it becomes a"cancer"in the copper smelting industry.Aiming at the problem of removing arsenic from contaminated acid in copper smelting,based on the chemical precipitation of iron and arsenic compounds and the principle of colloidal flocculation,a method of using ferric oxide for the treatment of waste acid is proposed.The release of iron in the iron is mainly studied in the following three aspects:The effect of time,temperature,acidity,liquid-solid ratio and stirring speed of iron oxide on the total iron leaching from Ferric oxide and the ability to remove arsenic;Response surface method to optimize experimental leaching conditions,study on the removal effect and mechanism of arsenic in waste acid under the best leaching conditions;Study on the continuous leaching behavior and leaching kinetics of ferric oxide in waste acid.According to the effect of time,temperature,acidity,liquid-solid ratio,and stirring speed on the iron leaching of ferric oxide and the arsenic removal ability,the preliminary conclusion is that when the temperature is 65?,the stirring speed is 200r/min,the acidity is 150 g·L^-1,and the leaching time is 600 min,a better leaching effect of total iron can be achieved.Treating arsenic-containing contaminated acid under this condition,the arsenic treatment efficiency can reach 95%,ferric oxide can be used to treat arsenic in contaminated acid,and as the acidity increases,the reaction dissolves more iron.The better the effect,the higher the recovery efficiency of iron in the solution.When there is a certain treatment efficiency,the experimental leaching conditions are optimized by the response surface method and study the removal effect and mechanism of arsenic under the best conditions.The experimental results show that in acidity,leaching temperature,leaching time,liquid-solid ratio four among the factors,the leaching temperature and the liquid-solid ratio have the most significant effect on the leaching of total iron.The degree of influence is as follows:leaching temperature>liquid-solid ratio>acidity>leaching time.The best process for the leaching process is:acidity is 180 g·L^-1,leaching temperature is 85?,leaching time is 600 min,liquid-solid ratio is 125 m L:4.36 g.Under this condition,the total iron leaching concentration was 3139.85 mg·L^-1,which was close to the predicted value of the model.At the same time,the treatment effect of arsenic in sewage acid can reach 99.42%.By XPS,XRD and other analysis of the solid material after the reaction,it is speculated that the removal process of arsenic in the dirty acid is:iron oxide releases a lot of iron ions in the waste acid,and a large amount of Fe³⁺in the solution reacts with As to generate iron arsenate and precipitate it.In addition,the remaining iron ions will hydrolyze the Fe OOH generated,adsorbing As in the waste acid.Under the combined effect of the two,it could achieve the effect of treating the copper smelting waste acid.Through the study of the continuous leaching behavior and leaching kinetics of ferric oxide in contaminated acid,the following conclusions were drawn:the leaching rate of ferric oxide was faster in the first 60 minutes,and then the leaching rate gradually decreased within 720 minutes the p H of the acid solution did not change significantly.By scanning the solid with an electron microscope,it was found that the morphology of ferric oxide changed from the original compact state to looser and formed some irregular eroded pores after being eroded by the acid.On the basis of the continuous leaching experiment,the whole leaching process can be divided into two stages of 10-60 min and 60-720 min for kinetic study.The continuous leaching process of ferric oxide in contaminated acid can be described by a shrinking unreacted nuclear model.The results of kinetic fitting showed that the solid phase layer diffusion controlled the apparent activation energy of 8.1663 KJ·mol^-1 at 10-60 min,and was controlled by the chemical reaction process at 60-720 min,and the apparent activation energy of the reaction was 43.0429 KJ·mol^-1.