Cradle Arc Mowana copper mine and process plant
Cradle Arc Mowana copper mine and process plant

Cradle Arc has received an independent test report from SGS South Africa confirming the applicability of Dense Media Separation (DMS) for its flagship Mowana copper mine.

Botswana Accordingly, it remains the board’s intention to pursue a DMS installation in due course as the development plan for the upgrades to the Mowana processing plant progresses.

The DMS has been identified as a low capex expansion option to potentially increase production at Mowana to approximately 22 000 tpa of copper in concentrate.

At an increase in throughput to approximately 2.6 Mtpa with reduced cash costs, an increased NPV of up to US$245 million (from the current base case NPV of US$87 million) would be realised.

Test work has demonstrated that DMS pre-concentration can be deployed at Mowana on all low oxide ores (those that contain less than 25% acid soluble copper).

The following key metrics were derived by Cradle Arc from the independent test work:

  • A mass yield of 30-40%, and an expected copper recovery of in excess of 85% can be expected
  • Mill feed grades in excess of 2% can be expected, nearly double the current ROM
  • An optimal crushing top size of 10-12mm should be designed for with respect to the upgrade project
  • Good rejection of gangue minerals is achieved, including carbon and silicon (with more than 75% being rejected).

Initial DMS preparatory work is anticipate to be completed within Q1, 2018.

Cradle Arc is also generating a new block model for the resource at Mowana, which will enable it to complete new mining schedules that incorporate the DMS study results as well as the additional knowledge gained from a re-logging exercise.

To complete the technical aspects of the DMS upgrade project, Wardell Armstrong International has been appointed to re-model the Mowana resource. Such modelling includes the re-logging of drill core and confirmatory assay on selected samples allowing a fuller interpretation of the data base.

As a result of this re-modelling and the abovementioned SGS work, Cradle Arc anticipates that it will then be able to update the Mowana resource and reserve statement.

“Our expectation that DMS upgrades should be deployed at Mowana has been confirmed by SGS’s report.  We are now focused on working closely with our selected contractors to finalise the budget and implement the strategy to upgrade the processing plant,” says Kevin van Wouw, CEO of Cradle Arc.

“We are confident that we can rapidly move the Mowana mine from operating at its current nameplate capacity capable of producing 12 000 t of copper per annum, to operating at an improved capacity, that should enable copper production to increase to, potentially, more than 20 000 t of copper per annum. This is expected to dramatically improve cash flows and the net present value.”

Feature image credit: Cradle Arc (Mowana processing plant)