Optimization of Hydrochemical Leaching Process of Kaolinite Fraction of Bauxite with Response Surface Methodology

Abikak Y. Bakhshyan A. Dyussenova S. Gladyshev S. Kassymzhanova A.
July 2024 Multidisciplinary Digital Publishing Institute (MDPI)

Processes
2024 #12 Issue 7

A technology for the hydrochemical processing of the kaolinite fraction of bauxite has been developed, and it involves preliminary chemical activation in a sodium bicarbonate solution and alkaline leaching in a recycled high-modulus solution with the addition of an active form of calcium oxide. Chemical activation allows for the transformation of the difficult-to-explore kaolinite phase to form easily soluble phases of dawsonite, sodium hydroaluminosilicate and bemite. An active, finely dispersed form of calcium oxide was obtained as a result of CaO quenching in Na₂SO₄ solution at elevated temperature and pressure. Using a central composite design (CCD) via response surface methodology (RSM), the technological leaching mode was achieved. The influence on the leaching process was studied by adjusting the CaO/SiO₂ ratio, temperature, alkaline solution concentration and duration. It was found that the determining factors are the concentration of the leaching solution and the temperature. At a stable CaO/SiO₂ ratio, a combination of these two factors determines the duration of the process to achieve the predicted degree of recovery. The results of experiments carried out using the developed model of the leaching process confirmed the validity of the calculated indicators, with an error of 2.01%. In an optimal technological mode at a Na₂O leaching solution concentration of 260 g/L, a temperature of 260 °C, a CaO/SiO₂ ratio of 1.5 and a leaching time of 5 h, the extraction of Al₂O₃ into the solution was 89.7%, which is close to the value of 87.9% predicted by the model.

alkaline leaching , bauxite , factors , kaolinite fraction , response surface methodology

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Institute of Metallurgy and Ore Beneficiation JSC, Satbayev University, Almaty, 050000, Kazakhstan

Institute of Metallurgy and Ore Beneficiation JSC

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