Currently designed only as an open pit, going underground would add a further 50,000 ounces to output, according to a preliminary economic assessment that looks at expansion plans.
This would boost the net present value of the project to US$200mln at an estimated capital cost of US$37mln.
The cash operating cost of an underground mine are forecast to be US$664 an ounce, giving all-in sustaining costs of US$845 per ounce. The net operating cash flow generated is estimated to be around US$30mln a year.
KEFI’s exploration director Jeff Rayner said: "As we continue to make excellent progress on financing and preparing for the development of the Tulu Kapi open pit mine, we are pleased with the positive results of our preliminary economic assessment for the underground mine potential.
“When combined, the estimated total annual gold production increases to approximately 150,000 ounces.
“We expect the development of the underground mine to commence after the open pit has begun generating cash flow and repayment of development finance, and so it will increase the net operating cash flow of the project, thereby strengthening the economic potential of Tulu Kapi.
“We look forward to reporting progress on this, and other exploration targets that stand to leverage the Tulu Kapi infrastructure, in due course."