How Talc deposits are formed ?
Talc deposits result from the transformation of existing rocks under the effect of hydro-thermal fluids carrying one or several of the components needed to form the mineral (MgO, SiO2, CO2). Tectonics plays a major role in the genesis of a talc deposit. It enables hydro-thermal fluids to penetrate the rock, creating a micro-permeability that facilitates reactions in the mass. The size and shape of talc deposits depend upon the intensity of the hydrothermal activity which corresponds to the climate of a low temperature metamorphism. Pressure and deformations, both concurrent with and subsequent to this transformation, determine the crystallinity of the talc ore in the deposit.
Extraction and Processing
- Overburden Removal : Most talc deposits are open-pit mines. The waste rock covering the talc vein is removed using giant shovels that can shift up to 1,500 tons of rock an hour.
- Talc Extraction: The exposed talc is then extracted using shovels. Even at this early stage, the different ore types are sorted as they are extracted from the seam.
- Sorting:Sorting the different talc ores according to their talc content and brightness is a key phase of the production process. Techniques include hand sorting, state-of-the-art laser and image analysis technology or flotation.