Process for recycling saltcake

Abstract

Saltcake generated by the aluminum industry is completely recycled through a process that simultaneously liberates the contained aluminum metal and dissolves the soluble salt fluxes to recover aluminum metal, aluminum oxide and salt fluxes by temperature controlled wet milling, rapid solids-brine separation and solar pond evaporation of the resulting clear brine. The temperature of the feedwater is 70.degree. F. or less to retard the exothermic reaction of aluminum metal with water, thereby minimizing the loss of metal to oxidation and the evolution of undesirable gases. Low temperature is maintained by using process water at or below the desired temperature, by forcibly cooling the mill with ambient air, and by controlling transit time through the mill to avoid excessive grinding of the aluminum metal. Minimizing the production of fine aluminum particles reduces the total surface area of aluminum metal available for exothermic reacton with the water. Particle size is controlled by monitoring the aluminum metal product and slurry from the mill in order to adjust the feed rate of saltcake and water to the mill. Particle size control also permits maximum recovery of aluminum. The slurry from the mill is rapidly separated by filters and clarifiers into aluminum oxide and clear brine. The brine is then evaporated in solar pond(s) to recover salt fluxes.

Dependencies are inferred from the claim text.