The mined ore is hauled a short distance of between 2 km and 7 km by contracted trucks to the crushing plant. The ore is first crushed in a tertiary stage crushing plant from a feed of 350 mm to less than 16mm in size. It is then conveyed to the grinding circuit where the material is added to a rod mill along with water to form slurry. The rod mill instantly grinds the ore after which it is sized using a hydrocyclone. Any oversized material is passed to the ball mill for a further grinding to the desired size of 80%. The ore is now ready for flotation.
Flotation is the process that concentrates the ore. This is done by agitating the ore slurry in cells with air bubbles. By adding a combination of fatty acid reagents, the fluorspar in the ore attaches itself to the air bubble to float to the top of the cell. This product is skimmed off leaving the waste in the bottom of the cell.
The process is conducted in a series of “rougher” and “cleaner” cells that successively concentrates the ore from 40% CaF2 in the feed material to a minimum of 97.0% CaF2 in the final concentrate. The water in the final product is then removed in a thickener and a rotary drum filter. This produces a filter cake concentrate containing approximately 11,0% moisture. The samples are analysed in the company’s assay and research laboratory. The waste product is pumped to the tailings dam and settled water is recycled to the plant for reuse.