Aluminum Gray And Efficient Separation And Extraction And Recycling Use

Considering resource shortage, environment pollution and economy development, regenerating aluminum resource has been increasingly concerned. The aluminum ash containing massive metal aluminum will be produced in the process of aluminum production, while aluminum can be recovered and utilized for many times, and the energy consumed in the process of recovery is only 5% of which in production of primary aluminum. However, aluminum recovery through traditional frying ash method in which secondary aluminum ash do not be used anymore is lower, and will cause the waste of aluminum resource and the pollution of environment.The paper took the aluminum ash from Baotou Aluminum Co. Ltd as study object, developed a novel efficient separation reagent of the aluminum ash which made the aluminum recovery improve remarkably. And the quadratic aluminum ash, which was treated by means of lye leaching, met the requirements of returning electrolyzer and recycling basically. The main experimental contents and results include the following four aspects.(1) The metal aluminum contents in the aluminum ashes with different particle sizes, which were obtained by ball milling and screening, were measured. And the effect of particle sizes on metal aluminum distribution in the ash was researched. The results showed that, the metal aluminum contents in aluminum ashes with particle sizes above 0.9mm accounted for about 72% in the total metal aluminum amount of all ashes; the rest 12% metal aluminum were in aluminum ashes with particle sizes lower than 0.15mm.(2) A novel efficient separation reagent of the aluminum ash was researched and developed. The effects of several factors such as addition amount of separation reagent, working temperature, addition amount of Na3AlF6, content of Al2O3 and different additives on aluminum recovery were investigated. The best working temperature of the separation reagent was 680℃. The optimized formula was: 42.5%NaCl,42.5%KCl, 10%Na3AlF6 and 5% CaF2·The aluminum recovery reached 93.5% when employing the formula of the separation reagent in the recovery process of the aluminum ash.(3) According to the results from laboratory experiments of aluminum ash recycling, related equipments were designed and manufactured, and pilot scale tests of application research of the novel separation reagent were developed. The experimental results showed that, in the recycling process of aluminum ash, the metal aluminum recovery increased to 92% from 71% as addition of the separation reagent; and in the production process of metal aluminum, the content of the metal aluminum in aluminum ash produced was decreased to 11% from 45% as addition of the separation reagent.(4) The methods of treating the quadratic aluminum ash were first proposed in the paper. The effects of different methods including one-time water leaching process, secondary water leaching process, hot ball-milling leaching process and lye leaching process on leaching rate of elements such as Na, K, Cl and Si were compared. The results showed that the effect of lye leaching process was best, and the optimal process conditions were that the NaOH concentration was 1.5mol/L, the leaching temperature was 70℃. The leaching rate of the elements including Na, K, C and Si were separately 85%,80%,95% and 55%. All of these have met the requirements of returning electrolyzer and recycling basically.