Production of lithium compounds from lithium concentrate obtainedin the aluminum hydroxide production process at Eti̇ aluminum plant

This study investigates the recovery of valuable commercial lithium compounds from concentrated lithium cake, a by-product of the Bayer process applied at the Eti Aluminum Factory in Turkiye. The lithium cake, obtained from the processing of bauxite ore containing 300–350 ppm lithium through the Bayer process, contains approximately 68% lithium aluminum carbonate hydroxy hydrate [Li2Al4(CO3)(OH)12·3H2O]. In order to economically recover the lithium within the cake, leaching experiments were conducted using deionized water at different temperatures, reaction durations, and solid-to-liquid (S/L) ratios. The optimum conditions were determined as 220°C, 2 hours of reaction time, and a 1/10 S/L ratio. Under these conditions, lithium recovery efficiency reached 86.7% based on ICP-OES analysis. The lithium content in the cake, initially 3.82% Li2O, decreased to 0.79% in the solid residue after leaching, while the lithium concentration in the solution reached 1448 ppm. The solid waste obtained after the reaction was found to contain 84.7% boehmite, indicating its potential for reuse within the Bayer process. From the lithium solution obtained under optimum reaction conditions, high-purity lithium compounds such as lithium carbonate, lithium phosphate, lithium fluoride, lithium iron phosphate, and lithium hydroxide were produced. Among these, lithium carbonate, lithium phosphate, and lithium fluoride were successfully synthesized with high purity. A process flow diagram was developed for the production of lithium carbonate with 99.6% purity, suitable for use as a raw material in lithium-ion battery manufacturing.