Effect of Temperature on Rare Earth Elements Recovery from Coal Fly Ash Using Citric Acid

Abstract

Production of fly ash as a solid waste of coal combustion rises as the need of electricity in Indonesia increases. In 2020, the amount of fly ash produced is estimated to reach 9.72 million tons. Utilization of coal fly ash is still limited while poor handling on abundant amount of this material can cause air, soil and water pollution. This research aims to recover rare earth elements contained in coal fly ash. In this study, the recovery of La, Ce, Nd, Dy and Y was done using citric acid. Magnetic phase of fly ash with particle size less than 38 μm from PLTU Tanjung Awar-awar Tuban was leached with 300 mL citric acid of 0.5 M using solid/liquid ratio of 1:10. The experiment was carried out in various temperature of 26°C and 45°C. Liquid samples were taken at 2, 5, 10, 15, 30, 60, 90, 120 and 240 minutes to be analyzed. The five elements recovered was found to rise until the end of the leaching period. Value of relative recovery also increases along with leaching temperature. The greatest recovery value is reached by yttrium that are 51.00% for leaching at 26°C and 83.35% at 45°C.