Recycling of White Aluminium Dross: Production of Potash Alum

Abstract

Aluminium dross, an industrial by-product generated in large quantities, is fairly rich in aluminium content. Even though there are means of recycling (pyrometallurgical and hydrometallurgical routes), still a large amount of aluminium dross is landfilled. This research article emphasizes on recycling of aluminium dross by the production of potash alum. Powdered aluminium dross is allowed to react with potassium hydroxide, followed in sequence by filtration, slow addition of sulphuric acid coupled with constant stirring of the solution, heating the solution and cooling it in the cold water bath to produce potash alum. The crystals of potash alum are formed in the solution after a few hours. Analysis of the product potash alum, parent liquor and the residual liquor shows that nearly 89.2% of aluminium present in the parent liquor is successfully transferred into the product potash alum crystals. Potash alum finds its applications in wastewater treatment plants, pharmaceutical cosmetic industries and leather tanning units.