The feed size of a talc ball mill depends on mill model, liner type, ball grading, and whether it works in open or closed circuit. For talc processing, the recommended feed size is controlled to balance throughput, energy consumption, and protection of talc’s lamellar structure.
Standard feed size range
For most industrial ball mills used for talc:
- Typical feed size: 10 mm ~ 25 mm
- Optimum feed: less than 20 mm
- Harder gangue-rich talc ore: better limited below 15 mm
If the incoming ore is larger than 25 mm, the grinding efficiency drops sharply, media wear increases, and hard iron-bearing gangue will accelerate liner abrasion and introduce secondary iron contamination.
Two common scenarios
- Primary ball mill (coarse grinding)
Feed size: 10–25 mm. It takes material from secondary crushing, reduces talc to intermediate fineness, and releases embedded iron impurities for later magnetic polishing. - Secondary ball mill (fine grinding / regrinding)
After pre-classification, the feed size is much finer, usually 0.5–3 mm. This stage is used for further fine pulverization of pre-ground talc powder.
Important notes for talc
- Talc is soft (Mohs hardness 1), but mixed quartz and iron gangue are abrasive. Oversized feed causes heavy wear of metal liners and steel balls, bringing extra iron into talc powder and lowering whiteness.
- Do not use extremely fine feed into the primary ball mill. Excess fines cause material cushioning effect, reducing grinding impact and wasting energy.
- When using non-metallic liners and ceramic media for low‑iron talc production, the feed size should be kept at the lower end (≤15 mm) to reduce impact stress on ceramic components.
For a talc primary ball mill, the standard feed size is 10–25 mm, with the best target below 20 mm. Closed-circuit crushing and screening are required to guarantee stable feed size before entering the ball mill.
