Examining alumina out of alunite ore through thermaland mechanical activation

In this study, the extraction of alumina from the alunite ore, found in the Kutahya/Turkey-Saphane Mining deposit belonging to Eti Mining Operations General Directorate, by thermal and mechanical activation methods was investigated. The experiments were designed using the Response Surface Methodology with Central Composite Design option. Thermal activation processes involved NaOH, KOH leaching after calcination, and thermal degradation of alunite + NaOH, alunite + KOH mixtures at different temperatures to absorb Al and K into the solution by water leaching. In the mechanical activation experiments, water leaching was carried out after grinding the alunite milled in the vertical stirred mill at different concentrations of NaOH, KOH and the mixture of alunite + NaOH, alunite + KOH in the mill. Thus, it is aimed to pass Al and K into the solution. As a result of these works, calcination at 30 min/800oC with water leaching was performed for 60 minutes, and potassium solution was recovered with 85.18% efficiency. After the calcination of the sample + NaOH mixture at 600oC, it was determined that the highest-yield absorption into the solution was achieved because of water leaching at 100 oC for 65 minutes at 900 rpm and 15% solid ratio. To recover Al that passed into the solution, formed the precipitated yield with HCl was calcined at 1100 oC for 240 min. and alumina was extracted with 89.89% recovery rate and 91.24% of Al grade, and 98.32% recovery rate and 99.67% of K grade.