The mill expansion is expected to increase the operation's average annual gold output by between 75,000-100,000oz for the first five years, starting in 2020, with mill capacity expanding by more than 50% through the addition of a crusher, grinding mill and leach tanks.
The expansion project has a calculated internal rate of return of more than 20% and, together with other projects at Ahafo, extend profitable production through at least 2029.
"Combined with Subika underground, which was successfully completed in November 2018, the mill expansion will increase Ahafo's production to between 550,000 and 650,000oz/y through 2024, while lowering life-of-mine processing costs," said Newmont Goldcorp CEO Tom Palmer.
"The project also accelerates the efficient processing of stockpiled ore and supports profitable development of Ahafo's highly prospective underground resources, which continue to demonstrate considerable upside."
Ahafo is expected to achieve record production in 2019 at improved costs, driven by higher grades from the Subika openpit, a full year of mining from Subika and the mill expansion.
Capital costs for the AME are estimated at between US$140-180 million. Commercial production began at Ahafo in 2006 and, in 2018, the gold sold from the operation was 436,000oz at all-in sustaining costs of $864/oz.
Over the past six years Newmont has successfully built 11 new mines, expansions and projects on four continents - on or ahead of schedule and at or below budget. These projects include Akyem and the Phoenix Copper Leach in 2013, the Turf Vent Shaft in 2015, Merian and Long Canyon in 2016, the Tanami expansion in 2017, and Twin underground, Northwest Exodus and Subika in 2018, and the Tanami power project in 2019.
The company also completed the acquisition of Cripple Creek and Victor in 2015 and delivered a profitable expansion at the mine in 2016.
The company's NYSE-quoted equity (NYSE:NEM) traded in positive territory on Tuesday, adding as much as $1.04 intraday to a high of $40.93; just short of its recent 12-month high of $41.23. The company has a market capitalisation of $33.4 billion.