Recovery of sodium from alumina-extracted fly ash using concentrated sodium carbonate solution

Abstract

A novel method for the recovery of sodium from alumina-extracted fly ash (AEFA) using concentrated Na 2 CO 3 solution is presented. Sodium was efficiently extracted from AEFA, which was mainly composed of NaCaHSiO 4. The factors influencing the process were systematically investigated, and the optimal conditions were determined to be: reaction temperature = 180 °C, Na 2 CO 3 concentration = 170 g/L, liquid-to-solid ratio = 10 mL/g, and reaction time = 2 h. Under optimal conditions, a low Na 2 O content of 1.02 wt% of the products, with Na 2 O extraction rate of 93.79% was achieved. The results indicated that this process was more effective than the recovery of sodium from AEFA using a dilute NaOH solution. Furthermore, this process avoided the production of a dilute NaOH solution, therefore lowering the energy consumption during the concentration and recycling of sodium, when compared with the NaOH-based route. Therefore, the recovery of sodium from AEFA using concentrated Na 2 CO 3 solution is more suitable for use in industrial applications.