Ore is mined, crushed and sent directly to the mill for concentrating of the valuable metal it contains. Alternatively, ores containing leachable minerals may be sprayed with dilute sulfuric acid to recover those metals, over a period of time. The process is conducted in an environmentally sound manner by ensuring capture of metal-bearing solutions.
Overburden generally lacks any recoverable minerals and contains only trace amounts of metals.
Naturally occurring rock which has been mined but is not of sufficient value to warrant further processing. This rock is usually separated from the ore body and set aside in another part of the mine. Waste rock may be used for road construction at the mine site. The portion of washed or milled ore that remains after metal-bearing minerals have been removed in the flotation process. In this process ore is ground to a fine sand consistency, mixed with water and biodegradable reagents to create a slurry that is piped into flotation tanks where it is agitated with air causing a froth.