Abstract: A method and apparatus for extraction of zinc ore is disclosed. The zinc ore is mixed with a dilute acid, typically sulfuric acid, in a leaching process and is thereafter filtered through an appropriate number of stages. The filtration removes some of the heavier metals such as lead. Purification removes other elements, typically copper and cadmium. After purification, the filtrate is introduced on the cathode side of a tank having an anode and cathode separated by a permeable diaphragm. The elemental zinc deposits on the cathode while reconstituted acid accumulates on the anode side. The acid is recovered and recycled to the leaching step. The rate of recovery of zinc at the cathode is substantial.

Abstract: A method and apparatus for recovery of elemental zinc from zinc scrap, typically skimmings, is disclosed. Zinc skimmings include chlorine as a zinc chloride contaminate. Chlorine liberation in zinc electrolytic refining techniques in an acid bath has failed heretofore because the elemental chlorine attacks the equipment as hydrochloric acid as well as producing a reversible chemical reaction. This method and apparatus capture the chlorine gas and remove it, enabling the process to continue indefinitely where elemental zinc is recovered at a cathode in a zinc sulfate bath which is separated from the anode by a permeable diaphragm. The process separates and removes chlorine and also collects the metal at the cathode, separates the sulfuric acid from the catholyte by transferring it by electrodialysis across the diaphragm into the anode compartment for re-use and also by this recycle enables the process to continue in operation indefinitely.

Abstract: A method of purifying a galvanizing and/or metal cleaning plant pickle liquor to enable repetitive re-use of the acid which includes the steps of placing a cathode and an anode in the spent acid (pickle liquor) and passing a DC current therethrough. The cathode and anode are separated in the pickle liquor solution by a permeable diaphragm which permits transfer therethrough of the metal ions and the acid anions. Metal molecules in the liquor such as iron, zinc, etc., are recovered upon their adherence to the cathode. The recovery is about 80 to 90 percent of the total metal ion content on that side of the diaphragm. The iron in solution is removed from that side of the tank and it is transferred to a precipitator tank. There, a neutralizing base is added to precipitate the remaining iron typically as a ferric hydroxide out of the tank.