Raymond Mill for Lithium Hydroxide – Product Application Analysis and Feasibility Plan

1. Produktübersicht

1.1 Introduction to Lithium Hydroxide

Lithium hydroxide (LiOH) is an inorganic compound appearing as a white crystalline powder. Its physical properties are as follows:

Lithium hydroxide is mainly used in the preparation of lithium salts, lithium‑based greases, electrolyte for alkaline batteries, and absorbent solutions for lithium bromide chillers. With the rapid development of the new energy vehicle industry, battery‑grade lithium hydroxide, as a key raw material for ternary cathode materials, has seen continuously growing market demand.

1.2 Introduction to Raymond-Mühle

The Raymond mill (roller suspension mill) is a dry grinding equipment widely used for non‑metallic mineral processing. The spodumene Raymond mill is specifically designed for grinding lithium ore raw materials such as spodumene and lepidolite with Mohs hardness below 7. It uses the compression action of grinding rollers and rings to crush and grind materials into fine powders of 80‑600 mesh. The Raymond mill is one of the key pieces of equipment in the front‑end process for lithium battery cathode materials (such as lithium carbonate and lithium hydroxide).

In lithium extraction processes, to increase the specific surface area of particles and enhance the reaction speed and efficiency of the impurity‑containing electrolyte during heating and stirring, the electrolyte needs to be sent to a Raymond mill for grinding into powder. The European‑type Raymond mill is also a common choice for lithium ore grinding, serving as an ideal dry‑process powdering solution.

2. Technical Requirements for Lithium Hydroxide Grinding

2.1 Product Quality Requirements

Different grades of lithium hydroxide have different fineness requirements:

2.2 Special Challenges in Grinding Lithium Hydroxide

Grinding lithium hydroxide presents the following special challenges:

1. Hygroscopicity – Lithium hydroxide readily absorbs carbon dioxide and moisture from the air, leading to wall sticking and material blocking.
2. Strong alkalinity – Its strong alkaline nature causes corrosion to equipment.
3. Adhesiveness – It tends to stick, affecting grinding efficiency and discharge smoothness.
4. Strict purity requirements – Battery‑grade applications demand “zero tolerance” for metallic impurities.
5. Heat sensitivity – Local overheating may degrade the material.

3. Technical Analysis of Grinding Lithium Hydroxide with a Raymond Mill

3.1 Working Principle of Raymond-Mühle

The main components of a Raymond mill are a fixed base ring and rotating grinding rollers. The base ring is equipped with a grinding ring at its edge. As the rollers rotate around the vertical axis, centrifugal force presses them tightly against the grinding ring. Scrapers rotating together with the rollers spread the material on the base plate between the rollers and the ring, where it is crushed by compression and attrition. The pulverised powder is blown up by the airflow from the fan, passes through the classifier, and the fines that meet the fineness requirement are carried into the cyclone collector for collection.

3.2 Feasibility Parameters for Processing Lithium Hydroxide with Raymond Mill

3.3 Applicability Assessment of Raymond-Mühle for Lithium Hydroxide

✅ Suitable applications:

• Coarse powder processing of industrial‑grade lithium hydroxide (80‑200 mesh)
• Pre‑grinding of precursor materials such as spodumene calcine
• Processing of intermediate lithium hydroxide products with less stringent metallic impurity requirements
• Preparation of primary lithium ore powders (100‑150 μm)

❌ Unsuitable applications:

• Ultrafine grinding of battery‑grade lithium hydroxide (D50 = 3‑8 μm)
• Applications with strict limits on metallic impurity content

3.4 Main Risks of Using Raymond Mill for Lithium Hydroxide

1. Metal contamination risk – The industry generally does not recommend traditional mechanical compression mills (like Raymond mills) because they easily introduce iron filings and have sealing difficulties.
2. Sealing issues – Lithium hydroxide is hygroscopic, and Raymond mills cannot completely isolate air and moisture.
3. Fineness limitation – Raymond mill products are typically 80‑400 mesh, far from the micron‑level required for battery grade.
4. Wall sticking – The adhesiveness of lithium hydroxide can cause blockages in the grinding chamber and pipelines.

4. Feasibility Plans

4.1 Plan 1: Coarse Powder Processing for Industrial‑Grade Lithium Hydroxide (Raymond Mill Recommended)

Application scenario: Coarse powder processing of industrial‑grade lithium hydroxide with fineness requirement of 80‑200 mesh and less stringent metallic impurity limits.

Process flow:

Bulk LiOH → Backenbrecher (coarse crushing) → Elevator → Storage hopper →
Electromagnetic vibrating feeder → Raymond mill (grinding) → Classifier (separation) →
Cyclone collector → Pulse dust collector → Finished product packaging

Recommended equipment configuration:

Raymond mill model reference:

Key precautions:

• Feed material must be thoroughly dried to below 1% moisture content; otherwise, wall sticking and blocking will occur
• All material‑contact parts should be made of 304/316L stainless steel or lined with ceramic/polyurethane to resist strong alkaline corrosion
• The system should operate under full closed‑circuit negative pressure with a pulse dust collector
• PLC fully automatic control is recommended for remote operation and automatic adjustment

4.2 Plan 2: Ultrafine Grinding for Battery‑Grade Lithium Hydroxide (Raymond Mill NOT Recommended)

Application scenario: Ultrafine grinding of battery‑grade lithium hydroxide requiring D50 = 3‑8 μm and D97 ≤ 15 μm.

Recommended equipment: Nitrogen‑protected fluidized bed opposed‑jet mill

Reasons for recommendation:

• No metal contamination – High‑speed airflow causes particles to impact each other; no grinding media or mechanical wear, ensuring high purity
• Low‑temperature grinding – Air expansion absorbs heat, keeping the chamber cool and preventing thermal degradation
• Closed‑circuit nitrogen protection – Oxygen content can be controlled to single‑digit ppm levels, preventing moisture absorption and oxidation
• Explosion‑proof design – Integral explosion‑proof construction with PID dynamic balance for process safety

Reference equipment parameters:

4.3 Plan 3: Pre‑Grinding of Spodumene Calcine (Mature Raymond Mill Application)

Application scenario: Pre‑grinding of calcined spodumene in the sulphuric acid process for lithium extraction.

Spodumene calcine is a mixed material typically requiring dry grinding to about 200 mesh, which is well within the capabilities of a Raymond mill. Common equipment types for spodumene calcine grinding include R‑series Raymond mills and HC pendulum mills, covering powder production from 80 to 2,500 mesh.

Recommended process:

Spodumene calcine → Jaw crusher → Raymond mill → Classifier → Collector → Next process (acid roasting, etc.)

4.4 Equipment Selection Comparison Summary

5. Conclusions and Recommendations

5.1 Overall Conclusion

A Raymond mill can be used for grinding lithium hydroxide, but its applicability has clear boundaries:

1. Coarse powder processing of industrial‑grade lithium hydroxide (80‑200 mesh): FEASIBLE. The Raymond mill is mature, has lower capital cost, and offers high capacity – it is an economically sound choice.
2. Ultrafine grinding of battery‑grade lithium hydroxide (D50 = 3‑8 μm): NOT FEASIBLE. The fineness cannot be achieved, and there is a risk of metal contamination; the industry does not recommend it.

5.2 Implementation Recommendations

If a Raymond mill is chosen for lithium hydroxide grinding, we recommend:

1. Strict moisture control: Feed material must be thoroughly dried to below 1% moisture content.
2. Corrosion protection: All material‑contact surfaces should be stainless steel or ceramic‑lined.
3. Sealing upgrades: Enhance system sealing to prevent moisture absorption and dust leakage.
4. Environmental accessories: Equip with high‑efficiency pulse dust collectors to ensure emission compliance.
5. Trial grinding: Request the equipment supplier to conduct a trial run with your material to verify performance.
6. Automation: Use PLC control systems to ensure production stability and efficiency.

If producing battery‑grade lithium hydroxide, we recommend:

Directly evaluate a nitrogen‑closed‑loop fluidised‑bed jet mill system. Although the initial investment is higher, it guarantees product purity and fineness.