The Zimbabwe-based Blanket gold mine continues to perform in line with the expectations of operator Caledonia Mining Corporation, having set a new quarterly production record in the third quarter of this year of 21 772 oz.

This production record is 3% up from production in the third quarter of 2022 and took production for the first nine months of this year to 55 244 oz, thereby leading to Caledonia reiterating its confidence in reaching its slated guidance for the year of between 75 000 oz and 80 000 oz.

Rich Legacy

The Blanket mine has a long history of producing gold in Zimbabwe, coming into production in 1904.

In 1965, Falconbridge acquired the mine property and increased gold production to an average of 1 587 oz a month, while Kinross acquired the mine in 1993 and added extra capacity to the carbon-in-leach plant with capacity of about 3 800 t/d to treat an old tailings dump, together with the run-of-mine ore.

During tailings treatment years 1995 to 2007, gold production from Blanket mine topped 3 880 oz a month; to date, in excess of one-million ounces of gold have been produced from the mine.

A wholly-owned subsidiary of Caledonia Mining Corporation completed the purchase of the Blanket mine from Kinross during April 2006, following which Caledonia made considerable capital investments in the mine’s underground, surface and township facilities.

These investments culminated in the commissioning of the Number 4 Shaft expansion project at the end of September 2010, which increased Blanket mine’s hoisting capacity from that shaft from 500 t/d, to 3 000 t/d.

The Number 4 Shaft is equipped with an automated loading system, which Caledonia states was the first such use case in Zimbabwe, which sequentially fills two 6 t ore skips which are hoisted from the 789 m level to surface.

The use of such an automated system reduces the risk of ore loading accidents and injuries, and reduces labour force costs, spillage and skip loading times, while it also serves to increase hoisting capacity, ensure precise ore tonnage accountability and enhance winder efficiency, as well as reduces loading and hoisting costs.

Further, Caledonia Mining Corporation started construction of a new Central Shaft in August 2015, which enabled the miner to reach deeper levels of up to 1 200 m from surface.

The Central Shaft, commissioning of which was completed in the first quarter 2021, provides access for horizontal development in two directions on two levels below 750 m, thereby increasing production and extending the life-of-mine (LoM).

"We have invested heavily in Blanket over the last seven years, including investment this year to construct a new tailings storage facility which is expected to have a life of at least 15 years, based on the current production profile, and will support production well into the future,” says Caledonia Mining Corporation CEO Mark Learmonth.

Meanwhile, between the third quarter of 2022 and early in 2023, Caledonia Mining Corporation commissioned and set into operation a 12 MW solar photovoltaic plant to supplement as much as 25% of Blanket mine’s daily power demand and enhance sustainability.

"The solar plant . . . continues to operate well. The solar plant is owned by Caledonia rather than by Blanket and therefore the economic benefit arising from the solar plant has been realised in the consolidated all-in sustaining cost rather than the on-mine cost,” he notes.

More recently, Learmonth points out, an offer was received from a global solar operator to buy the solar plant. “The sale process is underway.”

He adds that the Blanket mine continues to provide the company with a solid foundation, providing Caledonia Mining Corporation with a platform for its other growth projects in Zimbabwe.

These include, Caledonia Mining Corporation reported in October, its exploring of options to raise $250-million to develop its Bilboes project into what it says could be Zimbabwe's biggest gold mine.

The Bilboes project could potentially produce about 170 000 oz/y of gold, boosting Caledonia Mining Corporation's total bullion output to about 250 000 oz.

Going forward, Caledonia Mining Corporation intends to operate Blanket gold mine in 2024 within the same guidance range as 2023 of between 75 000 oz to 80 000 oz, while also continuing to explore the mine with the objective of further upgrading inferred mineral resources, thereby extending the LoM.