Alumina Production from Calcium Aluminate Slags with a Novel HCl-Based Metallurgical Process

A novel, HCl-based metallurgical process is investigated aiming at the production of α-Al₂O₃ from calcium aluminate slags. The process includes the following stages: (a) leaching of the slag with aqueous HCl to dissolve the aluminum content and separate SiO₂ as a filterable precipitate, (b) HCl_(g) purging precipitation of the dissolved aluminum in the form of aluminum chloride hexahydrate salt (AlCl₃∙6H₂O, ACH), (c) partial removal of dissolved metal impurities from the impure ACH by acetone washing and (d) calcination of the higher purity ACH to produce α-Al₂O₃. Under optimum leaching conditions, approximately 90% of aluminum is successfully extracted. An ACH purity of 97.5% was achieved after the precipitation and purification process. After calcination of the ACH, α-Al₂O₃ of 98.5% purity was produced.