Randgold Resources has started commissioning of the sulphide circuit at the Kibali gold mine in the Democratic Republic of Congo.
Kibali began production from its open pit through its oxide circuit in September 2013 and completion of the sulphide circuit will significantly advance its development as a gold mining complex.
Kibali mine will have a life of 18 years and is expected to produce about 600,000oz of gold a year for the first 12 years.
Randgold is developing and operating Kibali, in which it has a 45% interest.
AngloGold Ashanti has a 45% stake in the project and Sokimo owns the remaining 10% interest.
Speaking at the BMO Global Metals and Mining conference in Miami, Florida, Randgold Resources chief executive Mark Bristow described Kibali as a work in progress.
"While the plant processes ore from the open pit mine, the underground mine is still being developed and has just accessed the first underground ore," Bristow said.
Bristow noted that the Kibali mine posted a bottom-line profit in its first quarter of operation in the three months to December 2013, and is on-track to meet its production guidance of 550,000oz for this year.
"While much of the gold mining industry has been left in disarray by the downturn in the gold price, Randgold's long-term growth strategy remains intact," Bristow added.
"In addition to the upside associated with Kibali's main open pit and underground ore bodies, which is still being evaluated, our exploration team is also hunting for fresh opportunities within its vast lease areas, and a number of exciting, if early stage, prospects have already been identified."
"Elsewhere in the Democratic Republic of Congo and West Africa, we're aggressively exploring our extensive ground holdings for new discoveries."