The Catoca diamond mine is located near Saurimo in the Lunda Sul province of Angola. The African diamond mine currently ranks as the world’s fifth biggest diamond mine by reserve. It has an expected mining life of 30 years.
The open-pit mine is owned and operated by Sociedade Mineira de Catoca, a joint venture of the state-run mining company Endiama (32.8%), Russia-based diamond producer Alrosa (32.8%), China Sonagol (18%), and Odebrecht Mining (16.4%).
The diamond mine produced 6.7million carats (Mct) of rough diamonds and earned revenue of $579m in 2012. It accounts for about 6% of the world diamond production and about 70% of Angola’s diamond output.
Catoca diamond mine geology and reserves
Catoca is the biggest among all kimberlite pipes situated in the Lucapa structure in North-eastern Angola. The Catoca kimberlite pipe, underlying a surface area of about 64 hectares, is considered to be the fourth biggest diamond-rich rock formation in the world.
The pipe comprises of volcanogenic-sedimentary rocks. The inner ring of the vertical tube is made up of porphyric kimberlites, while the central part is filled with kimberlitic breccias.
The proven and probable diamond reserves of the mine are estimated at 130Mct.
Catoca mine history
The Catoca kimberlite pipe was discovered by Companhia de Diamantes de Angola (Diamang) in 1965. Artisanal method of mining was carried out during the exploration. Endiama conducted feasibility studies for the commercial exploitation of the kimberlite during 1980s.
The Sociedade Mineira de Catoca joint venture was formed in 1994 to build and operate the mine. The first diamonds from the Catoca processing plant were recovered in 1997. The expansion of the processing plant was completed in 2005.
Mining and ore processing at Catoca diamond mine
Catoca employs open pit mining method with the use of bulldozers and dump trucks. The current operating depth of the open-pit exceeds 200m. The mining depth is expected to reach 600m by 2034. Caterpillar trucks, and Caterpillar and Liebherr excavators are used for the mining operation.
The first processing plant at Catoca commenced operations in 1997 with a processing capacity of 4Mtpa. A second processing plant was installed in 2005 raising the combined processing capacity to 10Mt of ore per annum.
The extracted ore is transported by truck to the processing plant. The ore is first crushed and then sent to the autogenous grinding mill via head belt conveyor. The milled ore passes through five different stages of particle sizing.
The X-ray recovery unit of the X-ray luminescence (XRL) separation facility separates diamonds from the process stream. The diamonds are refined in the refinement section and concentrated in a jigging machine.
Diamonds are separated from the concentrate though froth flotation. The separated diamonds are cleaned, handpicked, weighed, and containerised.
Contractors involved with Catoca diamond mine
ALROSA’s Yakutniproalmaz Institute developed the production complex at Catoca and also provides technical assistance for the mine.
Solcon was awarded the contract for providing HRVS-DN medium voltage soft starters for the mine. The HRVS-DN medium voltage soft starters eliminate high inrush current enabling stable power supply.
The soft starter also reduces the high starting torque, thereby avoiding damage to the conveyor belt, and increases the life expectancy of the conveyor mechanical system.
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