Chemical Development of the Calsinter Process for Recovering Resource Materials from Fly Ash

摘要

Laboratory-scale tests of several methods for the recovery of resource materials from fly ash have led to the development of a sinter/dilute-acid leach process, called Calsinter. In this process, fly ash is sintered with added CaSO sub 4 and CaCO sub 3 at 1200 exp 0 C and the sinter product is subsequently leached with 4 N H sub 2 SO sub 4 . Results of experiments using Calsinter show that aluminum recovery increases with the sintering temperature in the range 800 to 1200 exp 0 C and exceeds 95% at the optimum sintering conditions. An attractive feature of the process is that flue gas desulfurization sludge can be substituted for CaSO sub 4 without reduction of the metal values recovery. Other resource materials such as Fe, Ti, Mn, U, and Th can also be recovered by including a solvent extraction step, which provides primarily for the recovery of a pure A1 sub 2 O sub 3 product. In addition, this process provides for effective management of potentially hazardous materials (e.g., Ba, As, Hg, Cd, Se, Cr, Pb, and Ag) so that the resulting waste is more environmentally stable than the original waste materials. (ERA citation 06:019706)