Mining and Processing at Keysbrook
Mining and processing of the mineral sands deposit at Keysbrook will use well-proven techniques, widely used in Western Australia. The method employs wet screening, then gravity separation using flowing water over spiral concentrators, to separate the heavy minerals from the sand.
Chemicals, such as those used in Gold mining, are not used in this process. One additive, a flocculent, is used in small quantities to purify water being recycled for the spiral gravity processing.
Processing at Keysbrook will produce a heavy mineral concentrate which will be trucked to a mineral separation plant at Picton where the final ilmenite, leucoxene and zircon products will be separated.
Mining
Mining will be carried out using a scraper. Ore will be transported by the scraper to a hopper, then fed over a wet screen. Any material 2mm or over is screened out at this stage and returned directly to the mined pit.
The mining at Keysbrook is a straightforward, well established process with no realistic potential to impact on the environment. It will involve the excavation of sand by scraper to an average depth of 2 metres, mostly above the water table, and the removal of 2.7% of the material as zircon and titanium minerals. It is a proven process of gravity separation, followed by the replacement of the sand and topsoil for rehabilitation. No chemicals are used in the operation. The mining is in many ways similar to the earthworks for land subdivision.
Gravity Concentrating
During screening, the ore is mixed with water, then pumped as a slurry to the spiral concentrator. In the concentrator, differences in mineral specific gravity is used to separate light material (such as quartz sand) from the valuable heavy minerals such as Ilmenite, Leucoxene and Zircon. The heavier particles gravitate to the centre of the spiral, are progressively removed and stored ready for trucking to final processing at Picton.
The lighter material is carried by the flowing water to the outside of the spiral trough, where it is collected and pumped back to the mined pit.
Heavier particles to the centre
Spiral Concentrator
Water is Recycled
Water used in the Gravity Separation process is recycled. To clean the water of any fine suspended particles (such as clay) a binding material, or flocculent, is added to clump (or flock) the particles together.
Flocculants are commonly used to remove particles of impurity which would otherwise be too fine to be caught by a filter.
For example, flocculants may be used in both swimming pool and drinking water filtration to remove microscopic particles that would otherwise cause the water to be cloudy and which would be difficult or impossible to remove by filtration alone. Water authorities commonly use flocculants for clarifying water.
The Mining Process
