Experimental study of rare earth element enrichment from Indonesian coal fly ash: Alkaline leaching

Rare Earth Element plus Yttrium (REY) is an critical element in green technology and consumer goods. Due to its limited supply, it is necessary to look for alternative sources of REY which one of the potential candidates is coal fly ash. Two samples of coal fly ash which originated from Indonesia were leached in an alkaline solution in order to remove Si and increase REY content. Samples were collected from pulverized coal power plant in East Java (sample T) and West Java (sample I). Leaching conditions were studied including concentration of NaOH, ratio of volume of liquid (L) to weight of solid (S) and leaching time. It was found that the optimum condition was reached at NaOH concentration of 8M, L/S ratio (10 mL: 1 g) and leaching time of 120 min. At this condition, percent removal of Si and REY enrichment were respectively 56.22 and 30 for sample I, and 33.75 and 24 for sample T. © 2020 Trans Tech Publications Ltd, Switzerland.