Optimizing High Purity Aluminum Extraction from Bauxite: A Comprehensive Hydrometallurgical Approach

Bauxite is the primary source material for producing alumina, and this research aims to use hydrometallurgical techniques to obtain a solution with a higher concentration of aluminum from bauxite. The study further explores methods to purify this solution and produce high-purity α-alumina. Several parameters were tested to determine the optimal solution for leaching all the aluminum from bauxite. The purification process involved batch ion exchange using two different resins: a cationic resin (Lewatit® TP207) and a cheating resin (Puromet MTS950). Leaching experiments revealed that 3 M sulfuric acid for 4 h at 90°C with a solid-to-liquid ratio of 1:10 achieved successful aluminum extraction. Using S950 resin in batch ion exchange at pH 0.5 for 2 h at 25°C, it was observed that 65% of the iron and only 1.5% of the aluminum were adsorbed. This resin was then employed in the continuous ion exchange process at a flow rate of 2 BV (bed volume). After passing through three series columns, 89% of the iron was adsorbed, but there was a 15% loss of aluminum. Finally, the solution was precipitated at a pH 3 using ammonium hydroxide. The resulting precipitate, calcined at 1200°C, successfully produced α-alumina with a purity of 99.8%.