A simple expansion to the process plant completed around mid-2015, saw its production capacity output increase well above this to its current 3.3 million tonnes per annum ROM and 165 000 – 175 000 ounces per annum of gold. The mine produced 166 285 oz of gold for the 2016 year.
Otjikoto outperformed expansion forecasts while it took B2Gold only three years to deliver the gold-producing Otjikoto after acquiring the Greenfield project late in 2011. The mine’s journey since then has continued with equal if not greater momentum.
Located about 300 km north of Windhoek between Otjiwarongo and Otavi, the mine is 90% owned by B2Gold and 10% by EVI Mining, a local empowerment group. When first built, Otjikoto was designed to comfortably deliver around 140 000 ozpa of open cast gold resources from a 2.8 Mtpa ROM rate for just over 12 years.
“This is a phenomenal achievement considering the expansion simply entailed incorporating additional leach tanks, pumps and large diameter pipes – successfully implemented to the point where it now outperforms the planned 365 tph and delivers around 420 tph,” said Mark Dawe Managing Director, B2Gold Namibia.
“We have also increased our mining equipment fleet to accommodate these higher volumes and will add another five mining trucks and a 250 tonne excavator during the year to ensure we continue to operate comfortably,” Dawe added.
The latter half of 2015 also saw B2Gold introduce its nearby B2Gold-discovered Wolfshag deposit into its production mix. Dawe describes this as a “very rich ore body” strategically ideal to blend with the Otjikoto pit’s lower grade ores (0.6 to 2 g/t) and improve overall grade recoveries.
Consequently, the operation is expected to average about 1.59 g/t in 2017. Wolfshag also opens up the potential to process older stockpiles as the mine ages – thereby increasing the overall ounce profile of the mine quite significantly.
Dawe also attributed Otjikoto’s overall operating success to the process plant (design and built by B2Gold management and Lycopodium). “We have some of the highest overall metallurgical recoveries in the world – over 98% generally and sometimes close to 99% recovery,” he said.
“This is thanks to the mine’s geology, easily liberated gold mineralogy and high proportion of coarse gold, but more so because of the unconventional and “unique” plant design which sees all the milled product processed through the gravity circuit before being leached.
“We have some of the highest overall metallurgical recoveries in the world – over 98% generally and sometimes close to 99% recovery,” Dawe concluded.