NMC Battery Recycling（2）

Extraction process

1. P204 Extraction and impurity removal

The purpose of P204 extraction and impurity removal is to deeply remove impurity metal ions such as Fe, Al, Ca, Cu, and Zn from low-acid leachate. P204 extraction and impurity removal utilizes P204's extraction ability for different metal ions. In a sulfuric acid system, the extraction order of metal ions such as Fe³⁺, Fe²⁺, Zn²⁺, and Mn²⁺ precedes that of Co²⁺, Ni²⁺, and Li+ ions. Therefore, under appropriate pH conditions, P204 extractant can be used to separate Fe³⁺, Fe²⁺, Zn²⁺, and Mn²⁺ from Co²⁺, Ni²⁺, and Li⁺ ions in the sulfuric acid system. The extraction order of various metal ions under different pH conditions is shown in Figure.

Extraction rate of metal ions

P204. The chemical reaction equation for the impurity removal process is as follows:

P204 extraction:2 (R'O)₂POONa + Me₂SO₄ → [(R'O)₂POO]₂Me + Na₂SO₄

Among them: (R'O)₂POOH is P204, R is the organic functional group of P204 extractant; Me is impurity metal ions such as Mn, Cu, Fe, Ca, Zn, Al, etc.

Saponification reaction: (R'O)₂POOH+NaOH＝(R'O)₂POONa+H₂O

1.1. P204 extraction

The low-acid leachate is pumped through a pipeline to a low-acid leachate storage tank for temporary storage. The low-acid leachate is then pumped from the storage tank via a pipeline into the extraction tank for a replacement reaction with the P204 extractant. In the extraction tank, the low-acid leachate undergoes multi-stage countercurrent extraction. The reaction temperature is controlled within the extraction tank range of 30°C–35°C, and the pH is maintained between 3.0 and 3.5. The extraction efficiency is maintained at ≥99%. Manganese ions in the low-acid leachate undergo a replacement reaction with Na+ ions in the extractant, entering the organic phase, while nickel and cobalt ions enter the raffinate (aqueous phase). The raffinate (aqueous phase) is then pumped via a pipeline to the P507 cobalt extraction process to produce cobalt sulfate. The organic phase enters the acid wash tank.

1.2. Pickling

In the pickling tank, the organic phase is washed with 0.5 mol/L sulfuric acid solution. The washing liquid containing nickel and cobalt ions is pumped together with the raffinate (aqueous phase) through a pipeline to the P507 nickel and cobalt separation process to produce cobalt sulfate. The organic phase after pickling is pumped into the stripping tank.

1.3. Stripping manganese

In the stripping tank, 2mol/L sulfuric acid solution is used to strip the manganese ions in the organic phase. The pH value in the stripping tank is controlled in the range of 2~3. Manganese is stripped out from the organic phase to obtain a crude manganese sulfate solution. After deep copper removal, it is pumped through a pipeline to the C272 manganese extraction section; the organic phase after stripping enters the deep iron removal tank.

The chemical reaction equation for stripping manganese is as follows:

[(R'O)₂POO]₂Mn + H₂SO₄ → 2 (R'O)₂POOH + MnSO₄

1.4. Deep copper removal

Sodium carbonate solution and sodium sulfide solution are added to the copper removal tank to further remove Cu²⁺ and Zn²⁺ from the crude manganese sulfate solution. After extensive copper removal, the crude manganese sulfate solution is filtered and pumped through a pipeline to the C272 manganese extraction section. The copper slag produced by the filter press has a moisture content of 30% and is temporarily stored in the plant's hazardous waste storage facility as solid waste awaiting identification.

1.5. Deep anti-iron

The organic phase is washed with 6 mol/L hydrochloric acid in a deep iron removal tank. The washed organic phase enters the acid washing tank; the iron removal wastewater is collected and sent to the sewage treatment station for further treatment.

The chemical reaction equations occurring in the deep anti-iron section are as follows:

R₃N+HCl=R₃NHCl

Fe₃++4Cl- =FeCl₄-

R₃NHCl+FeCl₄ - =R₃NHFeCl₄+Cl-

1.6. Acid washing

The purpose of acid washing is to remove hydrochloric acid from the organic phase. The wastewater from acid washing is collected and sent to a sewage treatment plant for further treatment.

1.7. Saponification

The saponification stage uses 400g/L sodium hydroxide solution as a saponifying agent, regenerating the P204 extractant for reuse in the P204 extraction and impurity removal process. First, P204 extractant is added to the extraction tank to prepare an organic phase with a 20% P204 concentration. A 32% caustic soda solution is then added to the P204 extractant to initiate a saponification reaction, replacing the Na+ ions with the H+ ions in the extractant.

2. C272 Manganese extract

The crude manganese sulfate solution obtained after stripping manganese in the P204 impurity removal section is pumped via a pipeline to the extraction tank of the C272 manganese extraction section for a displacement reaction. The manganese sulfate solution undergoes multi-stage countercurrent extraction in the extraction tank, maintaining a temperature of 30°C–35°C and a pH of 3.0–3.5. This allows manganese ions to undergo a displacement reaction with Na⁺ ions in the extractant, entering the organic phase and allowing trace impurities to enter the manganese extraction wastewater (aqueous phase). The organic phase is washed with 0.5 mol/L dilute sulfuric acid to remove trace impurities before entering the manganese stripping section. The manganese extraction wastewater (aqueous phase) and the organic phase acid wash wastewater are then fed into the sodium sulfate wastewater treatment system.

In the stripping manganese tank, 2 mol/L sulfuric acid solution is used to strip the manganese ions in the organic phase, and the pH value in the stripping tank is controlled within the range of 2-3. Manganese ions are stripped from the organic phase to obtain a high-purity refined manganese sulfate mixed solution, which is pumped through a pipeline to the manganese sulfate product storage tank. A portion of the manganese sulfate solution is evaporated, crystallized, and dried through MVR to produce battery-grade manganese sulfate. The remaining portion of the manganese sulfate solution is directly pumped to the ternary precursor workshop as raw material for the production of ternary precursors. The organic phase after stripping manganese is washed with hydrochloric acid and pure water, and then saponified with 32% sodium hydroxide solution to regenerate the C272 extractant, which is then fully reused in the C272 extraction tank.

3. P507 Cobalt extract

The P204 raffinate is pumped via a pipeline to the P507 extraction tank. After undergoing multi-stage countercurrent extraction, the P507 extraction tank is maintained at a temperature of 20°C–30°C and a pH of 3.0–3.5. This allows the cobalt ions to undergo a replacement reaction with the Na⁺ ions in the extractant, entering the organic phase and the nickel ions to enter the raffinate (aqueous phase). The raffinate (aqueous phase) is then pumped via a pipeline to the P507 nickel extraction section. The organic phase is washed with 0.5 mol/L sulfuric acid to remove trace nickel ions before entering the cobalt stripping section. The wash liquid containing nickel and lithium ions produced by the acid wash is pumped along with the raffinate (aqueous phase) via a pipeline to the P507 nickel extraction section.

In the cobalt stripping tank, 2mol/L sulfuric acid solution is used to strip the cobalt ions in the organic phase, and the pH value in the stripping tank is controlled in the range of 2-3. The cobalt ions are stripped from the organic phase to obtain a high-purity refined cobalt sulfate mixed solution, which is pumped through a pipeline to the cobalt sulfate product storage tank. A portion of the cobalt sulfate solution is evaporated, crystallized, and dried by MVR to obtain battery-grade cobalt sulfate. The other portion of the cobalt sulfate solution is directly pumped to the ternary precursor workshop as raw material for the production of ternary precursors. The organic phase after cobalt stripping is washed with hydrochloric acid and pure water, and then saponified with a 32% liquid alkali solution to regenerate the P507 extractant, which is then fully reused in the P507 extraction tank.

4. P507 Nickel extract

The P507 cobalt extraction residue is pumped to the P507 nickel extraction tank. The P507 extraction tank is maintained at a temperature of 20°C to 30°C and a pH of 3.0 to 3.5, allowing nickel ions to undergo a replacement reaction with the Na⁺ ions in the extractant and enter the organic phase. The organic phase is then washed with 0.5 mol/L sulfuric acid to remove trace impurities before entering the nickel stripping section. The nickel extraction wastewater and pickling wastewater are collected and then sent to the sodium sulfate wastewater treatment system.

In the nickel stripping tank, nickel ions in the organic phase are stripped with a 2 mol/L sulfuric acid solution, maintaining a pH within the tank between 2 and 3. Nickel ions are stripped from the organic phase to produce a crude nickel sulfate mixed solution, which is then pumped through a pipeline to the C272 magnesium extraction section. The organic phase after nickel stripping is washed with hydrochloric acid and pure water, followed by saponification with a 32% caustic soda solution to regenerate the P507 extractant, which is then fully recycled into the P507 nickel extraction tank.

5. C272 Magnesium extract

The crude nickel sulfate solution from the P507 nickel extraction section is pumped via a pipeline to the C272 magnesium extraction tank. The magnesium extraction tank's temperature is controlled between 20°C and 30°C, with a pH between 3.0 and 3.5. This allows magnesium ions to undergo a replacement reaction with Na⁺ ions in the extractant, entering the organic phase and nickel ions entering the raffinate (aqueous phase). The raffinate (aqueous phase) is a high-purity refined nickel sulfate solution, which is pumped via a pipeline to a nickel sulfate product storage tank. A portion of the nickel sulfate solution undergoes MVR evaporation, crystallization, and drying to produce battery-grade nickel sulfate. The remaining portion is directly pumped to the ternary precursor workshop as raw material for the production of ternary precursors. The organic phase is washed with 0.5 mol/L sulfuric acid to further remove impurities, resulting in a high-purity refined nickel sulfate solution.

The organic phase after acid washing enters the magnesium stripping tank, where magnesium ions are stripped with a 2 mol/L sulfuric acid solution. The pH in the stripping tank is controlled between 2 and 3. The magnesium ions are stripped from the organic phase, resulting in a magnesium sulfate solution that is pumped through a pipeline to a degraviation reaction tank. The organic phase after magnesium stripping is washed with pure water and then saponified with a 32% sodium hydroxide solution to regenerate the C272 extractant, which is then fully reused in the C272 magnesium extraction tank.

Sodium sulfide and steam are added to the degravity tank to remove nickel from the solution. After the precipitation reaction is completed, the material in the degravity tank is filtered to obtain nickel sulfide slag and filtrate (magnesium sulfate solution). The nickel slag has a moisture content of 30% and is temporarily stored in the hazardous waste storage warehouse on the factory site as solid waste to be identified. The filtrate (magnesium sulfate solution) is pumped into the magnesium precipitation reaction tank through a pipeline.

Add 30% sodium carbonate solution to the magnesium precipitation tank. After the precipitation reaction is completed, the material in the magnesium precipitation tank is filtered to obtain magnesium carbonate slag and magnesium precipitation wastewater (filtrate). The moisture content of the magnesium carbonate slag is 30%, and it is temporarily stored in the hazardous waste temporary storage warehouse in the factory as solid waste to be identified; the magnesium precipitation wastewater is discharged into the sodium sulfate wastewater treatment system.

Black mass extraction process flow chart