PROCESSING METHOD OF POSITIVE ELECTRODE ACTIVE SUBSTANCE WASTE OF LITHIUM ION SECONDARY BATTERY

A method for processing positive electrode active material waste of lithium ion secondary batteries, the waste containing cobalt, nickel, manganese and lithium, the method including: a carbon mixing step of mixing the positive electrode active material waste in the form of powder with carbon to obtain a mixture having a ratio of a mass of carbon to a total mass of the positive electrode active material waste and the carbon of from 10% to 30%; a roasting step of roasting the mixture at a temperature of from 600° C. to 800° C. to obtain roasted powder; a dissolution step including a first dissolution process of dissolving lithium in the roasted powder in water or a lithium-containing solution, and a second dissolution process of dissolving the lithium in a residue obtained in the first dissolution process in water; and an acid leaching step of leaching a residue obtained in the lithium dissolution step with an acid.