Mine Operations

Karebe Gold Mining Limited (KGML) combines underground mining at three KGML mines with tailings re-processing.

01. Mining

Underground operations are carried out using conventional underground Resue mining methods suitable for narrow vein mining. Resue mining is a method of mining that allows split face firing within stops to allow waste and ore to be mined separately, allowing dilution to be minimised. KGML operates a raising and winzing system and typical stopping techniques when mining. Ore is mined through drilling and blasting.

02. Transporting

Mined ore is loaded into cocopans, which run on a rail system to mining shafts. The ore is tipped into ore shoots/boxes from which it is loaded into skips, which hoist ore to surface. Mined ore is delivered by tractor and trailor to the main ore bin, from which it travels on conveyors to a series of gyro and jaw crushers.

03. Crushing

Ore is withdrawn from the ore and crushed by a gyro crusher and a series of three jaw crushers. After each crusher, material is fed over a vibrating screen; large particles are returned for recrushing, and fine material that passes through the screens progresses towards the next crusher and eventually on to the mill feed bin.

04. Milling

Ore is fed from the crushing line into the ball mill where it is ground with steel balls. Inlet dilution water is added to the mill feed chute to control mill slurry density. The ball mill discharges the resultant slurry via a trammel screen to the gravity concentrator. Any material not collected in the concentrator is pumped to a cyclone at the head of the CIP plant and treated with cyanide.

05. Gravity Circuit

Ore particles are subjected to a force of 60 gravities in a fluidization process in a Knelson Concentrator. When the concentration cycle is complete, concentrates are flushed from the cone into the concentrate launder through a patented multi-port.

06. Thickening

The tails empty to a tank and process water is added before being pumped to 100mm cyclone. The cyclone classifies the mill product into two fractions. The overflow fraction reports to a trash removal screen and then to a high thickener. The underflow fraction is controlled manually by opening or closing the thickener drain valve to attain the desired pulp density. The thickened pulp is pumped to the No 1 carbon in leach (CIL) tank.

07. CIL/CIP-Carbon
in Pulp Leaching

Cyanide is added into the No1CIL tank. To assist in the leaching process, hydrogen peroxide is added. Slurry overflows from the mechanically agitated leach tank through six mechanically agitated CIL tanks to ensure complete dissolution as a cyanide complex and adsorption onto activated carbon. Carbon recovered on the screen is delivered to a bulk bag for re-use. Tailings discharging from the tailings linear gravitate to the tailings section.

08. Tailings

Tailings slurry passing through the CIL tailings screen gravitates via pipes to the tailings dam in the immediate vicinity of the plant. Water on the tailings dam gravitates via a penstock into a return water pond from which return water is pumped to the plant for re-use.

09. Refining

Concentrates from the Knelson concentrator and elutions extracted from the pregnant carbon are further refined.