Comminution is a technical term used in mining and metallurgy to refer to the process of reducing the size of rocks or minerals by crushing and grinding. The main objective of comminution is to free valuable mineral particles from gangue (unwanted material) so that they can be processed and recovered in later stages, such as concentration or leaching.
Main stages of comminution
1. Crushing:
- Initial size reduction process.
- It is carried out in crushers (jaw, gyratory or cone) to bring large rocks extracted from the ore deposit to more manageable sizes.
- It generally reduces the particle size to centimeter ranges.
2. Grinding:
- Finer process that occurs after crushing.
- It is carried out in mills (ball, rod, SAG or autogenous), where the particles are reduced to smaller sizes, usually in the micron range.
- It is crucial to release the valuable mineral, especially in low-grade deposits.
Importance of comminution
- Mineral liberation: Allows for effective separation of valuable minerals from gangue.
- Process efficiency: Adequate particle size facilitates the recovery of minerals through flotation, magnetic separation, gravimetry, leaching, among others.
- Energy costs: Comminution consumes between 30% and 50% of the total energy of a processing plant, so optimizing this stage is key to reducing costs.
New technologies in comminution
- High pressure grinding rolls (HPGR): More energy efficient, ideal for hard minerals.
- Vertical mills: Require less space and energy compared to traditional mills.
- Selective fragmentation: Technologies that break particles based on their mineralogical properties.
