Factors Affecting the Bioleaching of Scandium from Fly Ash and Slag

The influence of preliminary crushing of fly ash and slag from lignite and its firing temperature on its structure is studied by electron microscopy. In addition, the influence of those factors on the bioleaching of scandium and the total quantity of rare earth metals and on the mass loss of the fly ash and slag and the target metals is investigated. Optimal firing conditions are chosen. Decrease in organic content of the fly ash and slag increases the bioleaching of scandium by ~80% and of rare earth elements by ~10%. The mass loss of the fly ash and slag on firing is around 3%. Principles are outlined for the accumulation of scandium in the organic component of the fly ash and slag, regardless of its distribution between the organic and mineral components of the lignite.