Zinc recovery method and zinc ferrite decomposition method

A zinc recovery method comprising:

• a high-temperature high-alkaline processing step that includes a contact step of bringing a raw material containing a zinc component and zinc ferrite or a processed raw material obtained by processing the raw material and an aqueous alkali hydroxide solution into contact with each other, a heating and temperature raising step of heating the raw material or the processed raw material and the aqueous alkali hydroxide solution brought into contact with each other in the contact step, and raising a temperature of the raw material or the processed raw material and the aqueous alkali hydroxide solution to a temperature reaching a boiling point of water exhibiting a boiling point rise, and a concentration maintaining step of maintaining a concentration of an alkaline agent contained in the aqueous alkali hydroxide solution at a time of stop of evaporation of a water content of the aqueous alkali hydroxide solution after the temperature reaches the boiling point, and that decomposes the zinc ferrite into a zinc oxide component and an iron oxide component by contact of the alkaline agent whose concentration is maintained in the concentration maintaining step and the zinc ferrite in the raw material or the processed raw material with each other;
• a first leaching step of, at a temperature less than the boiling point, bringing water into contact with the alkaline agent, the zinc oxide component, and the iron oxide component and leaching the zinc oxide component in an aqueous alkali hydroxide solution to obtain a first zinc-containing aqueous solution containing a zinc component and a slightly soluble material containing an iron oxide component not dissolved in the aqueous alkali hydroxide solution, thereby separating the slightly soluble material and the first zinc-containing aqueous solution from each other;
• and
• a zinc recovery step of recovering a zinc component originating from the first zinc-containing aqueous solution.