Abstract: A control system for a liquid-solid contacting apparatus and method therefor is designed to greatly minimize the dilution and contamination of the product streams as well as to perform the desired separation, concentration or conversion reactions at peak efficiency.The liquid-solid contactor comprises a loop; a plurality of loop valves dividing the loop into loading, pulse and regenerating sections; feed means for supplying a feed containing sorbable material to the loading section; sorption solid substantially filling the loop; regenerating means for supplying regenerating fluid to the regenerating section; first removal means for removing the material desorbed by the regenerating fluid from the loop; second removal means for removing the processed liquid from the loop; pulse inlet means for supplying a pulse liquid to the pulse section and an outlet means for removing a portion of the pulse liquid from the loop.

Abstract: An improved process for preparing highly concentrated salt solutions of metals of high purity from waste metal sludges at superior dissolution rates is achieved by preparing, concentrating and washing the sludge containing insoluble metal hydroxide under specific conditions to safeguard against the solids being exposed to air or dried out. The wet sludge is then dissolved in a dilute acid. The resultant solution can be used directly e.g. as make up in many electrolytic metal finishing processes to compensate for drag out losses occurred, or as the primary metal source in electrolytic processes employing insoluble anodes. Other specific uses for the process include the preparation of aluminum sulfate coagulants.

Abstract: Evolution of NOx fumes during dissolution of metal values in mineral acid solutions of nitric acid can be eliminated by the addition of small quantities of hydrogen peroxide to the acid solution.