Method for preparing cathode active material precursor for secondary battery, and preparation apparatus using same

1. A method for preparing a cathode active material precursor for a secondary battery, the method comprising:

moving a co-precipitation filtrate generated after a co-precipitation reaction to a co-precipitation filtrate storage tank;

removing a metal hydroxide by passing the co-precipitation filtrate through a filter;

reacting the co-precipitation filtrate from which the metal hydroxide is removed with sulfuric acid or nitric acid to produce an ammonium sulfate or an ammonium nitrate while removing ammonia from the co-precipitation filtrate from which the metal hydroxide is removed;

cooling and crystallizing the co-precipitation filtrate from which the metal hydroxide and ammonia are removed to precipitate a sodium sulfate;

filtering the precipitated sodium sulfate to separate the precipitated sodium sulfate from the co-precipitation filtrate from which the metal hydroxide and ammonia are removed;

drying the sodium sulfate separated from the co-precipitation filtrate and moving the co-precipitation filtrate separated from the sodium sulfate to a circulation concentration tank; and

heating the co-precipitation filtrate stored in the circulation concentration tank to a predetermined temperature for recycling and performing N 2 purging or bubbling.

2. The method for preparing of claim 1 , further comprising

increasing pH of the co-precipitation filtrate to 11.8 or more by adding NaOH to the co-precipitation filtrate in the co-precipitation filtrate storage tank.

3. The method for preparing of claim 1 , wherein

in the removing of the metal hydroxide by passing the co-precipitation filtrate through the filter, the metal hydroxide includes a metal hydroxide remaining in the co-precipitation filtrate and a metal hydroxide newly formed when NaOH is added to the co-precipitation filtrate.

4. The method for preparing of claim 1 , wherein

in the reacting of the co-precipitation filtrate from which the metal hydroxide is removed with the sulfuric acid or nitric acid to produce the ammonium sulfate or ammonium nitrate while removing ammonia from the co-precipitation filtrate from which the metal hydroxide is removed, the ammonia is NH 3 in a gaseous state.

5. The method for preparing of claim 1 , wherein

in the cooling and crystallizing the co-precipitation filtrate from which the metal hydroxide and ammonia are removed to precipitate the sodium sulfate, the co-precipitation filtrate is cooled to 10° C.

6. The method for preparing of claim 1 , wherein

in the heating of the co-precipitation filtrate stored in the circulation concentration tank to the predetermined temperature for recycling, the temperature is 45° C. or higher.

7. The method for preparing of claim 1 , wherein

in the co-precipitation reaction, a metal solution is prepared by dissolving a metal sulfate in distilled water, and the metal solution is injected into a reactor together with NaOH and NH 4 OH; and

instead of NH 4 OH in the co-precipitation reaction, the ammonium sulfate produced while removing the ammonia is re-dissolved and used.

8. A preparing apparatus of a cathode active material precursor for a secondary battery, the preparing apparatus comprising:

a co-precipitation filtrate storage tank configured to store a co-precipitation filtrate generated after a co-precipitation reaction;

a filter configured to remove a metal hydroxide from the co-precipitation filtrate;

an ammonia removal membrane contactor configured to remove ammonia from the co-precipitation filtrate from which the metal hydroxide is removed;

a sulfuric acid or nitric acid tank configured to supply sulfuric acid or nitric acid to be in contact with ammonia to the ammonia removal membrane contactor;

a cooling and crystallizing tank configured to cool and crystallize the co-precipitation filtrate from which the metal hydroxide and ammonia are removed to precipitate sodium sulfate;

a filter configured to filter the precipitated sodium sulfate to separate the precipitated sodium sulfate from the co-precipitation filtrate from which the metal hydroxide and ammonia are removed;

a dryer configured to dry the sodium sulfate separated from the co-precipitation filtrate;

a circulation concentration tank configured to store the co-precipitation filtrate separated from the sodium sulfate; and

an initial solution preparation tank configured to heat the co-precipitation filtrate stored in the circulation concentration tank to a predetermined temperature for recycling and to perform N 2 purging or bubbling.

9. The preparing apparatus of claim 8 , wherein

pH of the co-precipitation filtrate is increased to 11.8 or more by adding NaOH to the co-precipitation filtrate in the co-precipitation filtrate storage tank.

10. The preparing apparatus of claim 8 , wherein

the filter removes a metal hydroxide remaining in the co-precipitation filtrate and a metal hydroxide newly formed when NaOH is added to the co-precipitation filtrate.

11. The preparing apparatus of claim 8 , wherein

ammonia exists as NH 3 in a gaseous state in the ammonia removal membrane contactor.

12. The preparing apparatus of claim 8 , wherein

the cooling and crystallizing tank cools a temperature to 10° C.

13. The preparing apparatus of claim 8 , wherein

the initial solution preparation tank heats the stored co-precipitation filtrate to 45° C. or higher.

14. The preparing apparatus of claim 8 , further comprising:

an ammonium sulfate supply tank configured to store the ammonium sulfate in which in the co-precipitation reaction, a metal solution is prepared by dissolving a metal sulfate with distilled water, and the metal solution is injected into a reactor together with NaOH and NH 4 OH; and

instead of NH 4 OH in the co-precipitation reaction, the ammonium sulfate produced while removing the ammonia is re-dissolved and used.