Tulawaka Gold Mine, Tanzania
Tulawaka Gold Mine is situated 160km south-west of Mwanza inside the western portion of the Lake Victoria Goldfield, within the United Republic of Tanzania. The mine is owned 70% by African Barrick Gold (ABG) and 30% by Canada-based MDN Northern Mining.
ABG may be the operator of the mine. The house lies within the Biharamulo district (Kagera Area) license location and has a surface area area of 317km².
The mine consists of two ore bodies, which include the East and West Zones. Exploration and drilling activities in the east zone extended the mine’s life from 2011 to July 2012. Further drilling programmes are planned to improve the mine’s lifestyle past July 2012.
Commercial mining at the Tanzania mine
MDN commenced business production at the Tulawaka mine in March 2005. The mine produced sixty,134oz of gold having a 93.2% recovery price in 2010. The production in 2011 stood at 84,101oz of gold, an increase of 40% over 2010, with an general recovery price of 95.1% pushed by high graded stockpiles and large mill recoveries.
Geology, reserves and mineralisation of the Tulawaka gold mine area
Tulawaka gold mine lies in the western Rwamagaza greenstone belt with mineralisation hosted in a regional northwesterly striking Ushirombo shear zone.
The east zone is hosted in dominantly volcanogenic tuffaceous rock and bedded terrigenous sediment with small layers of silicate iron formations. Six different mineralised areas were identified through geological studies from the mine.
Proven and probable reserves in the mine as of December 2011 stand at 237,000t graded at 12.02g/t Au, which is equivalent to 91,000oz of Au.
Gold mineralisation at the east zone occurs inside quartz – tourmaline veins and minor sulphides within a 30m to 80m shear structure. The gold deposits are spread laterally at a depth of 100m. The mineralisation extends to a strike length of 1.1km. The east zone is highly mineralised compared to the west zone.
The gold deposits within the west zone are hosted inside of a sheared felsic intrusive. The gold is consociated with distributed sulphides, periodic quartz stringers and narrow veins. Mineralisation is open in all directions and spans to a strike length of 750m.
Mining at ABG and MDN Northern Mining’s Tulawaka east and west zones
The Tulawaka gold mine was initially developed as an open-pit operation in 2005. The east zone deposit was mined by the Tanzania-based company Caspian through an open-pit method. It was converted to underground mining operation in 2008.
The mine comprises of a dessert open-pit, an underground access ramp in the rear from the pit, waste rock dumps, an ore stockpile area, crushing plant, a processing plant and wastewater treatment and appurtenant facilities. The infrastructure being used for mining includes Komatsu shovels, loaders, dozers and haul trucks.
Processing plant and methods at the United Republic of Tanzania gold mine
The processing plant in the Tulawaka mine can process 1,480 tons a day (tpd) of ore.
The run of mine (ROM) ore stockpiled is crushed to high degree of fineness by using a primary jaw crusher. The crushed ore is transferred to a single stage semi autogeneous grinder (SAG) mill for grinding.
The ground ore is fed to the FFE liners, Knelson concentrators, a Gekko intensive leach reactor and electrowinning circuit to retrieve approximately 50% to 70% from the gold. The remaining gold is treated through carbon-in-leach (CIL) technology.
In the CIL method, the ground ore is transferred to cyanide leach tanks to generate pregnant solution. The solution is fed to a series of carbon adsorption agitated tanks where the gold sticks to the surface area of the carbon. The gold bearing carbon is poured into a heated sodium hydroxide-cyanide-water solution to detach the gold precipitates from carbon.
The gold precipitates are washed with higher pressure sprays, dried and melted at the smelter or refinery to produce pure gold dore bars or ingots for export. The solution is transferred to the tails thickener to recycle water for the processing plant.