Method for recovering valuable metal from waste battery material and waste cathode active materials

A method for recovering a valuable metal from a waste battery material and a waste cathode active materials, the method comprising:

• a reduction and heat treatment step comprising adding a reducing agent to a raw material including the waste battery material and the waste cathode active materials and heat-treating the raw material to obtain a lithium compound;
• a water washing step comprising adding water to the heat-treated raw material to obtain a first aqueous lithium solution in which the lithium compound is dissolved and a water washing residue not dissolved in the water;
• an acid washing step comprising performing a solid-liquid separation with the first aqueous lithium solution and the water washing residue, and adding an acidic solubilizer to the water washing residue to obtain an acid solution in which the valuable metals including lithium, nickel, cobalt, and manganese are dissolved and an acid washing residue not dissolved in the acidic solubilizer;
• and
• a valuable metal precipitation step comprising performing a solid-liquid separation with the acid solution and the acid washing residue, and adding a pH adjuster to increase pH to the acid solution to obtain a precipitation residue in which nickel, cobalt, and manganese are precipitated and a second aqueous lithium solution in which lithium remains,
• wherein the first aqueous lithium solution recovered in the acid washing step is used for the pH adjuster.