Vermiculite is a group of hydrated, laminar silicate minerals containing interlayer water. Rapid heating turns that water to steam and exfoliates the flakes; raw concentrate, exfoliated material and ground product are distinct states.
- Correct class
- Hydrated laminar silicate group
- Main transformation
- Thermal exfoliation / expansion
- Critical distinction
- Raw and expanded products are defined separately
Raw vermiculite and exfoliation
Raw concentrate has a micaceous appearance and water held between its layers. During rapid heating the resulting steam opens the layers into accordion-like particles, a physical transformation called exfoliation.
The low-density expanded material behaves differently from the raw feed. Grinding before or after expansion serves different purposes and can change product morphology.
Difference from perlite
Vermiculite is a laminar silicate-mineral group; perlite is an industrial material derived from hydrated volcanic glass. Both may expand on heating, but their mechanisms, product shapes and process windows differ.
A perlite flowsheet is therefore not copied directly to vermiculite; feed mineralogy and the required expanded product are validated separately.
Preparation steps
- Size separation of crude feed and removal of waste rock
- Drying and grading of concentrate
- Rapid thermal exfoliation when required
- Gentle handling, air classification or screening of expanded product
- Structure-aware controlled grinding for fine grades
Selection inputs
- Raw or exfoliated product target
- Feed PSD and moisture
- Bulk-density and particle-strength expectations
- Permitted fines and target fractions
- Boundaries for drying, expansion, collection and packaging
