Heat treatment method of waste cathode materials and lithium recovery method using same

A method of heat-treating a waste cathode material using a heat treatment furnace having a burner and an inlet, the heat treatment furnace being into a first region in which the inlet is disposed, a third region in which the burner is disposed, and a second region disposed between and connected to the first and third regions, the method comprising:

• supplying the waste cathode material via the inlet;
• generating a combustion gas including CO2 inside the heat treatment furnace and heating an interior of the heat treatment furnace using the combustion gas, by burning a hydrocarbon fluid by the burner inside the heat treatment furnace;
• reacting the waste cathode material in the heat treatment furnace using CO2 included in at least a first portion of the combustion gas before the first portion of the combustion gas is discharged from the heat treatment furnace and thereby producing lithium carbonate (Li2CO3) and residual metal oxide inside the heat treatment furnace;
• discharging a second portion of the combustion gas including CO2 to the outside of the heat treatment furnace, and re-supplying at least a portion of the second portion of the combustion gas including CO2 back to the heat treatment furnace via a re-supply port;
• cooling a third portion of the combustion gas discharged from the heat treatment furnace;
• and
• re-circulating the cooled third portion of the combustion gas into the heat treatment furnace via another re-supply port, which is positioned in the third region, such that a temperature of the third region is decreased and the temperature difference between the first region and the third region is reduced.