The production process of needle shaped wollastonite powder is a multi-step fine processing process aimed at maintaining its unique needle like structure and meeting the needs of different industrial applications. The following are the main production processes and key steps based on search results:
1. Raw material pretreatment
Cleaning and screening: Wollastonite raw ore needs to be cleaned with a high-pressure water gun to remove surface impurities, and preliminarily screened through a rolling screen to ensure the cleanliness of the raw materials.
Crushing: The cleaned ore is roughly crushed to 10-20 mesh by a jaw crusher to prepare for subsequent grinding.
2. Fine grinding and grading
Grinding equipment: Raymond mill, vertical mill or air flow mill are used for multi-stage grinding to maintain the fibrous structure. Vertical mills have gradually become mainstream equipment due to their good sealing and low energy consumption (30% more energy-efficient than Raymond mills).
Grading control: Particle size control is achieved through an airflow classifier to ensure that the product meets different fineness requirements such as 200~6000 mesh.
3. Surface modification (dry process)
Using silane coupling agents, titanium esters and other modifiers to treat powders, improving compatibility with polymer materials and enhancing reinforcement effects.
4. Collection and packaging of finished products
The ground powder is collected by a bag filter and finally packaged according to customer requirements (25kg woven bags or ton bags).
5. Key points of quality control
Physical testing: including hardness, density testing, and microscopic observation of the integrity of needle like structures.
Chemical analysis: X-ray diffraction (XRD) is used to verify the crystal composition, and acid washing is used to remove impurities such as calcium and aluminum.
Process parameter monitoring: Strictly control the grinding temperature, classifier speed, etc. to ensure that the aspect ratio and fineness meet the standards.
(Examples of production equipment: vertical grinding mill, air classifier, etc.)
Industry Trends
As the world’s largest producer, China’s annual production of wollastonite reached 550000 tons in 2021, accounting for 70% of global exports. High aspect ratio products (such as 6000 mesh) have a significant market premium due to technological breakthroughs.