A capacitive deionization process is provided. The capacitive deionization process includes a charging step of applying power to a capacitive deionization apparatus in a charging state and supplying charge water containing target dissolved ions to be precipitated to the capacitive deionization apparatus for a predetermined period of time, a discharging step of applying power to the capacitive deionization apparatus in a discharging state and supplying discharge water in which the target dissolved ions are in a saturated state to the capacitive deionization apparatus for a predetermined period of time, and a crystal recovery step of recovering a crystal of the target dissolved ions precipitated in the capacitive deionization apparatus and/or the discharge water.

A capacitive deionization process is provided. The capacitive deionization process includes a charging step of applying power to a capacitive deionization apparatus in a charging state and supplying charge water containing target dissolved ions to be precipitated to the capacitive deionization apparatus for a predetermined period of time, a discharging step of applying power to the capacitive deionization apparatus in a discharging state and supplying discharge water in which the target dissolved ions are in a saturated state to the capacitive deionization apparatus for a predetermined period of time, and a crystal recovery step of recovering a crystal of the target dissolved ions precipitated in the capacitive deionization apparatus and/or the discharge water.

Lithium recovery processes are described using concentration and conversion techniques. A vaporizer or membrane can be used to concentrate lithium and precipitate impurities. A conversion process can be used to replace anions in lithium bearing streams by adding a second anion and precipitating lithium in a salt with the second anion. Rotary separation can be used to separate the precipitated lithium salt.

Lithium recovery processes are described using concentration and conversion techniques. A vaporizer or membrane can be used to concentrate lithium and precipitate impurities. A conversion process can be used to replace anions in lithium bearing streams by adding a second anion and precipitating lithium in a salt with the second anion. Rotary separation can be used to separate the precipitated lithium salt.

Traditional methods for producing lithium carbonate involves thermal precipitation of a lithium sulfate purification liquid and a sodium (potassium) carbonate purification liquid to produce crude lithium carbonate to the production of a refined lithium carbonate wet product. The employment of “reverse feeding, non-circulating mother liquor”, “pre-precipitation supplementary impurity removal” and “high-efficiency desorption” can reduce industrial grade lithium carbonate sulfate radicals to 0.03%, increase the main content to 2.5N, reduce battery grade sulfate radicals to 0.008%, and stably increase the main content to 3N, or even reach the limit of 3.5N-4N. The high-efficiency desorption involves thermal precipitation with small temperature increases and thermal stirring washing, medium-high temperature strong desorption, and hydrocyclone separation. Impurities such as sulfate radicals that are chemically adsorbed and encapsulated in the peritectic core of lithium carbonate particles can be released into deionized water, which are then effectively carried away by a hydrocyclone separation liquid phase.

Traditional methods for producing lithium carbonate involves thermal precipitation of a lithium sulfate purification liquid and a sodium (potassium) carbonate purification liquid to produce crude lithium carbonate to the production of a refined lithium carbonate wet product. The employment of “reverse feeding, non-circulating mother liquor”, “pre-precipitation supplementary impurity removal” and “high-efficiency desorption” can reduce industrial grade lithium carbonate sulfate radicals to 0.03%, increase the main content to 2.5N, reduce battery grade sulfate radicals to 0.008%, and stably increase the main content to 3N, or even reach the limit of 3.5N-4N. The high-efficiency desorption involves thermal precipitation with small temperature increases and thermal stirring washing, medium-high temperature strong desorption, and hydrocyclone separation. Impurities such as sulfate radicals that are chemically adsorbed and encapsulated in the peritectic core of lithium carbonate particles can be released into deionized water, which are then effectively carried away by a hydrocyclone separation liquid phase.

A method of heat-treating a waste cathode material to recover lithium carbonate from the waste cathode material, and a lithium carbonate recovery method using the waste cathode material heat treatment method are provided. The method of heat-treating the waste cathode material includes heating an interior of a heat treatment furnace by burning a hydrocarbon fluid in the heat treatment furnace and producing lithium carbonate (Li.sub.2CO.sub.3) and residual metal oxide by reacting a waste cathode material in the heat treatment furnace with CO.sub.2 generated during burning of the hydrocarbon fluid.

A method of heat-treating a waste cathode material to recover lithium carbonate from the waste cathode material, and a lithium carbonate recovery method using the waste cathode material heat treatment method are provided. The method of heat-treating the waste cathode material includes heating an interior of a heat treatment furnace by burning a hydrocarbon fluid in the heat treatment furnace and producing lithium carbonate (Li.sub.2CO.sub.3) and residual metal oxide by reacting a waste cathode material in the heat treatment furnace with CO.sub.2 generated during burning of the hydrocarbon fluid.

A heat treatment apparatus used in a process of recovering lithium carbonate from a waste cathode material and a lithium carbonate recovery apparatus using the same are provided. The heat treatment apparatus includes a heat treatment furnace having an inlet through which an object to be treated is input and an outlet through which the heat-treated object is discharged, a support section rotatably supporting the heat treatment furnace, a burner provided in the heat treatment furnace to supply combustion gas to the heat treatment furnace, and an exhaust gas re-supply device re-supplying a portion of the combustion gas discharged from the heat treatment furnace to the heat treatment furnace, wherein the heat treatment furnace is divided into a first region in which the inlet is disposed, a second region connected to the first region, and a third region connected to the second region and in which the burner is disposed.

A heat treatment apparatus used in a process of recovering lithium carbonate from a waste cathode material and a lithium carbonate recovery apparatus using the same are provided. The heat treatment apparatus includes a heat treatment furnace having an inlet through which an object to be treated is input and an outlet through which the heat-treated object is discharged, a support section rotatably supporting the heat treatment furnace, a burner provided in the heat treatment furnace to supply combustion gas to the heat treatment furnace, and an exhaust gas re-supply device re-supplying a portion of the combustion gas discharged from the heat treatment furnace to the heat treatment furnace, wherein the heat treatment furnace is divided into a first region in which the inlet is disposed, a second region connected to the first region, and a third region connected to the second region and in which the burner is disposed.