Green Treatment And Utilization Of Hazardous Waste Aluminum Dross

Aluminum dross refers to the metal aluminum formed by the molten aluminum in contact with air during the processing of electrolytic aluminum,aluminum refining,aluminum smelting and casting,and combined with salt fluxes such as covering agent,slagging agent,and refining agent.Which formed mixture is mainly composed of metal aluminum,aluminum,iron,magnesium,calcium and other oxides,non-metal oxides,and fluoride salts and chloride salts.The aluminum nitride and aluminum carbide in the hazardous waste aluminum dross will produce ammonia,methane and other harmful gases in contact with water.The fluorine salt and chlorine salt will cause soil salinization,seriously pollute the environment and damage the health of operators.The aluminum dross is rich in metallic aluminum and aluminum oxide,which has recycling value.Therefore,the green treatment and utilization of hazardous waste aluminum dross is imperative.Therefore,this article has carried out the research on the environmental protection and utilization of aluminum dross.The results of the study are as follows:(1)In the aluminum nitride hydrolysis experiment,the effects of leaching time,leaching temperature,stirring rate,liquid-to-solid ratio,acid-base and additives on the hydrolysis process were studied.The results show that the leaching temperature is 90℃,the leaching time is 6 h,the stirring rate is 500 rad/min,the liquid-to-solid ratio is 12 ml/g,and NaOH with a solvent mass of 10%is added to promote the hydrolysis of aluminum nitride and the hydrolysis rate is 98.17%.(2)Use response surface methodology to study the pH changes during the hydrolysis of aluminum nitride.Use Design Expert software to design a quadratic rotation orthogonal test to investigate the significant degree of hydrolysis temperature(A),liquid-to-solid ratio(L/S,B)and reaction time(C)of the three factors on hydrolysis and the difference between the three factors.Whether there is an interaction.It is found that all three have a significant effect on the pH change during the hydrolysis of aluminum nitride in aluminum dross.The three have almost no interaction.After quadratic regression analysis,the equation is obtained.pH=10.00+0.12A-0.15 B+0.035C+0.020A·B-0.017A·C+0.0 18B·C+0.001167A2+0.00366B2-0.014C2Through some experiments,the fitting accuracy of the upper quadratic regression equation is verified.The results show that the maximum value of the relative error between the two is 2.43%,indicating that the equation has good guidance for the prediction of the pH of aluminum nitride hydrolysis.(3)In the experiment of extracting aluminum by ammonium sulfate mixed roasting and water leaching method,the influence of factors such as the molar ratio of total aluminum in ammonium sulfate and aluminum dross,roasting time,roasting temperature,leaching temperature,leaching time,and solid ratio of leaching liquid on the extraction of aluminum was studied..When the molar ratio of ammonium sulfate to total aluminum element is 0.84:1,the roasting time is 90 min,the roasting temperature is 350℃,the leaching temperature is 90℃,the leaching time is 80 min,and the liquid-to-solid ratio is 10 ml/g,the extraction rate of aluminum is 65.35%;calcined product calcined at 1250℃ for 3 h.According to XRD analysis,the calcined products are mainly inclusions such as alumina,a small amount of magnesia,silica and calcium oxide.According to XRF analysis,the alumina content in the calcined product is about 88.60%.