NMC Battery Recycling（3）

Crystallization drying

Three evaporation and crystallization units are set up to produce manganese sulfate, nickel sulfate and cobalt sulfate respectively. The main production processes include evaporation concentration and drying and packaging. The specific production process is described as follows:

1. Evaporation crystallization

The refined manganese sulfate solution, refined cobalt sulfate solution and refined nickel sulfate solution in the product transfer tank are transported to the MVR evaporation crystallization device through pipelines for evaporation and crystallization. The water vapor generated during the evaporation process is condensed and reused as production make-up water.

2. Dry packaging

The wet product material is evenly transferred to the disc dryer for drying through a screw feeder. Steam is used as the heat source and the drying temperature is between 100℃ and 120℃. The dried product material is then sent to the automatic packaging machine through a vacuum loader for packaging, and is respectively packaged into battery-grade manganese sulfate, battery-grade nickel sulfate and battery-grade cobalt sulfate.

Ternary precursor synthesis

The ternary composite cathode material precursor (ternary precursor for short) is a finished product based on nickel, cobalt and manganese. Its specific production process is as follows:

1. Liquid preparation

Refined nickel sulfate solution, refined manganese sulfate solution, and refined cobalt sulfate solution are separately delivered to a mixing tank in the precursor workshop via a metering system. Stirring and mixing produces a nickel-cobalt-manganese multicomponent salt solution. The nickel-cobalt-manganese molar ratio is 8:1:1, and the total metal ion concentration is controlled between 100g/L and 120g/L. The mixed salt solution is then delivered to a multicomponent salt solution storage tank via a transfer pump.

2. Synthesis

The prepared highly purified mixed salt solution, 32% sodium hydroxide solution and 20% ammonia water are transferred to their respective balance storage tanks, and then continuously added to the reactor at a certain flow ratio through a precision metering pump, and nitrogen is filled as a protective gas to prevent oxidation. By controlling the pH value in the reactor to 11-12, the reaction temperature to 55±5℃, the alkalinity to 12±1g/L, the solid content to 300±50g/L, the stirring speed to about 300±50rpm, and the reaction time to 15±2h, a ternary precursor with a particle size of about 8~12μm is synthesized.

The main reaction formula is as follows:

xNiSO₄ + yCoSO₄ + (1-x-y)MnSO₄ + 2NaOH → NiₓCoᵧMn₁₋ₓ₋ᵧ(OH)₂ + Na₂SO₄

3. Aging

The ternary precursor slurry generated by the synthesis reactor enters the aging reactor through a pipeline and is aged for 12 to 24 hours under the conditions of maintaining a reaction temperature of 55±5°C and low-speed stirring of 50 to 150 rpm. This allows the trace free Ni, Co, and Mn metal ions remaining in the mixed solution to continue to react and grow on the surface of the ternary precursor spheres, thereby improving the sphericity of the crystal nuclei.

4. Centrifugal separation

After the aging reaction is completed, the slurry is transported to the centrifuge via a transfer pump for solid-liquid separation. The solid material is transferred to the soaking tank, and the centrifugal wastewater is sent to the ammonia wastewater treatment system for further treatment.

5. Alkali bubbles

Add 32% sodium hydroxide solution and condensed water into the soaking tank, soak the solid material after centrifugal separation in 100g/L sodium hydroxide solution for about 2 hours, and then wash and filter the slurry after the alkaline soaking is completed.

6. Washing filter press

After the alkaline soaking process, the slurry needs to be washed twice and filtered. Condensate water is used for thorough washing to ensure that the sodium salt in the slurry is completely washed away. The washed slurry is separated into solids and liquids using a filter press. The solid precursor wet material is then fed into the drying section. The filter press wastewater is sent to the ammonia wastewater treatment system for further treatment.

7. Dry packaging

The wet ternary precursor material is evenly transferred to a disc dryer via a screw feeder for drying. Steam is used as the heat source, and the drying temperature is between 100°C and 120°C. The dried ternary precursor material is then passed through a vacuum feeder for screening, batch mixing, and iron removal. The screening machine uses a vibrating disc screen to separate the ternary precursor material of different particle sizes. The various particle sizes are then mixed according to the purchase order requirements. The mixed product is then de-ironed with an electromagnetic de-ironing device and packaged by an automatic baler for sale.

Cathode Solution specializes in the complete design and production of equipment for the production of ternary precursors, and can also provide technical services .