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Caledonia plans to extend depth of central shaft at Blanket gold mine in Zimbabwe

In light of the increased resource base, the boards of the Blanket Mine in Zimbabwe (Blanket) and Caledonia have approved a decision to invest further in the deepening of the central shaft.

“We are very pleased that the long track record of sustained resource growth at Blanket, particularly the continued discovery of resources at depth with good grade continuity, supports an extension of the central shaft project at Blanket,” comments CEO Steve Curtis.

“The central shaft is already a transformational project for our business and to extend the project an additional 250 m in depth including development on 34 and 38 levels will potentially secure Blanket’s operating future for the next 20 years taking exploration potential into account,” he continues.

The extension of the central shaft is expected to cost approximately $10 million and additional development of the two production levels below 30 level (990 m) is expected to cost approximately $8 million.

Total incremental project capital expenditure is therefore expected to be an increase of $18 million.

The capital cost of deepening the shaft before it is commissioned is expected to be significantly lower and less disruptive than would be the case if the shaft is extended after it’s commissioning by eliminating the duplication of infrastructure at the bottom of the shaft and site re-establishment of shaft sinking equipment and sinking crew.

The deepening of the central shaft is not expected to adversely affect the production target of 80 000 ounces of production by 2021 and is expected to extend the life of Blanket by potentially an additional four years beyond the current mine life, based on the existing Indicated and Inferred resources below 30 level to support operations at Blanket until 2031.

It is also expected to enable significantly increased operational flexibility at the mine as the deeper shaft will support operations over four production levels rather than the previously planned two levels.

This is expected to enable production to continue at the rate of 80 000 ounces until at least 2029 based on the current Inferred Resources below 30 level and potentially longer depending on future exploration success at depth extensions of known ore bodies above 30 level which will also enable exploration below 38 level (1230 m).

Blanket implemented a mid-shaft loading system at the beginning of November 2017 to enable central shaft to handle development waste, thereby alleviating some of the logistical pressure on number 4 shaft and ensuring that the horizontal development on 26 and 30 levels can start at least ten months earlier than the original project schedule.

The implementation of mid-shaft loading is also intended to allow number 6 Winze to hoist ore rather than ore and waste and should reduce waste haulage and hoisting via number 4 shaft due to the use of central shaft for the hoisting of development waste.

“Mid -shaft loading is not expected to have any negative effect on the plan to achieve 80 000 ounces of gold production by 2021 or to have any adverse impact on medium term production due to the increased operating flexibility the mid-shaft loading is expected to provide,” notes Curtis.

Feature image credit: Caledonia Mining