A process is provided that comprises (A) preparing a mass from one or more lithium ion batteries, wherein the mass comprises one or more selected from the group consisting of lithium, cobalt, nickel, manganese, iron, aluminum, and any combination of two or more of the foregoing; (B) contacting the mass with an acid to form a combination; (C) contacting the combination with a reducing agent so as to form an acid leachate, wherein the reducing agent comprises sodium thiosulfate; (D) adjusting the pH of the acid leachate so as to form a precipitate comprising aluminum; and (E) extracting from the acid leachate one or more selected from the group consisting of lithium, cobalt, nickel, manganese, iron, aluminum, and any combination of two or more of the foregoing