Recovery of Alumina From Coal Fly Ash By High Temperature Chlorination

The recovery of metals from low value sources will help reduce our national demand for foreign resources. The ash from bituminous type coals contains about 20 percent aluminum oxide and 20 percent iron oxides by weight. Recovery of these metals would provide an alternate source to the ores now used. The iron and aluminum materials in fly ash are recoverable by high temperature chlorination. Passing dry chlorine gas through a bed of nonmagnetic fly ash maintained at 850 to 900 degrees C. chlorinates the iron and aluminum constituents forming volatile compounds which are carried from the bed by the exit gas stream. In exploratory runs, 55 percent of the aluminum has been recovered as aluminum chloride in a nearly silica-free state