Size reduction of talc ore before ultra-fine milling is the coarse and medium crushing stage. Its goal is to break large talc boulders into uniform, mill-ready feed particles, liberate iron-bearing gangue, and protect talc’s natural lamellar structure without over-grinding.
1. Primary coarse crushing
Large raw talc blocks are fed into a jaw crusher for primary size reduction. It handles big feed lumps and reduces ore to 50–100 mm. This step only breaks big rock into manageable fragments, not fine powder. Avoid heavy impact at this stage to preserve talc flakes.
2. Secondary medium crushing
The crushed material then goes to an impact crusher for medium crushing. Impact crusher selectively fractures ore along mineral grain boundaries, separating talc from iron oxides and gangue. The target output size is 10–25 mm, which is the optimal feed range for talc ultra-fine mills.
If the ore contains a high proportion of hard gangue, a cone crusher can be an alternative, but cone crushing applies compressive force and may break talc lamellae more easily.
3. Closed-circuit vibrating screening
A vibrating screen is installed after secondary crushing to form a closed loop. Particles that meet the target size pass through to the next pretreatment steps. Oversized fragments are returned to the secondary crusher for re-crushing. Closed screening ensures consistent feed size and prevents large hard gangue from entering the mill.
4. Pre-removal of tramp iron and impurities
Before crushing, remove tramp iron and large dark gangue. After crushing, primary magnetic separation captures exposed iron-bearing minerals. This lowers iron load for downstream milling and protects mill liners from abrasive wear.
5. Key operational tips
- Do not over-crush. Too many fine particles created in the pre-milling stage cause agglomeration and hurt magnetic separation efficiency.
- Keep the crushing system enclosed to avoid external dust contamination.
- Control moisture properly; wet sticky talc will clog screens and crushers.
To reduce talc ore size before milling, use jaw crusher for primary crushing, impact crusher for secondary crushing, plus closed-circuit vibrating screening. This process produces uniform feed size, liberates iron impurities, and retains talc lamellar morphology, preparing qualified feed for subsequent ultra-fine grinding.
