Research On Recycling Technology Of Waste Solution From Chemical Milling For Aviation Aluminum

In the progress of chemical milling to aviation aluminum which produces largemounts of aluminum ions, when the concentration of aluminum ions reaches to75g/L,the chemical milling solution will be discharged, which would deserve the wasting ofa lot of chemical reagents, and also bring about tremendous pressure on theenvironment. If concentration of aluminum ions in the waste chemical millingsolution could be reduced to30g/L～40g/L, which would achieve the requirement ofreuse. Therefore, the way could save natural resources and reduce costs.The experiment takes the discharged chemical milling solution as research object.To begin with, identifing the main factors that impact aluminum ions to decline in themethod of physical and chemical crystallization. In the following, taking the measureof orthogonal test on the base of crystallization to optimize the conditions for thewaste recycling. Experimental results show that:(1) The method of physical and chemical crystallization can effectively reducethe content of aluminum ions in the waste chemical milling solution. Dilutting1.0times of the waste with distilled water and then standng it for a month, the crystalamount of aluminum ions is up to52.46%.(2) Main factors that influence the crystallization of aluminum ions in chemicalmilling solution are diluted multiple, the amount of added crystal seed, mixingmethods, mixing time and temperature.(3) According to the orthogonal test, it is known that the diluted multiple ofchemical millint solution and amount of the added crystal seeds are significant factorsin the crystallization of aluminum ions. The optimal conditions of acceleratingchemical million solution to crystallize are diluting1.2multiple of the waste, addingcertain amounts of crystal seeds which the ratio is0.3to1relative to aluminum-ionsbetween in crystal seeds and the diluted solution, keeping the temperature of35℃,mechanical stirring (speed:100r/min), stirring period is1h/d. The concentration ofaluminum in the chemical milling solution changes from41.43g/L to30.10g/L in48hours, the recycling rate of aluminum-crystallization reaches to27.35%, which hasachieved the lowest concentration of30g/L requested for aluminum ions in normalmilling work. The achievement of research enables recycling of the chemical milling waste,which not only saving costs but also pretesting the environment, so it has obviouseconomic benefits and good prospects.