JOHANNESBURG (miningweekly.com) – Aim-listed BlueRock Diamonds on Thursday reported that since it restarted operations at its Kareevlei mine, recovered grade has been improving from an initial 1.53 carats per hundred tonnes (cpht) to the most recent results of 3.02 cpht.

The company late last year embarked on a thorough overhaul of the main components of the processing plant.

The upgrades, which increased plant capacity and efficiency, started after the mine suffered a week-long suspension ordered by the Department of Mineral Resources, after an inspection on July 6, 2016, resulted in required changes to processing plant procedures, guarding rails on the plant and trackless mobile machinery.

Meanwhile, the mine recently achieved targeted volumes of around 1 250 t/d, “albeit not consistently owing to the continued exceptional levels of rainfall and to-be-expected commissioning issues arising from the plant laying idle for over six months”. 

In March, the plant processed 9 310 t and in April, so far, 3 330 t, from three days of production, until processing was halted by heavy rainfall on April 6.

“We anticipate that now that the commissioning issues are largely resolved and once the rain finally subsides we will be able to exceed our current monthly target of 25 000 t/m,” the company noted. 

The average diamond size recovered was significantly higher than has been mined to date, with BlueRock recovering about four times the number of diamonds in excess of 5 ct it usually does, including three diamonds over 6 ct, with the largest being 9.5 ct.

“Accordingly, value per carat and, more importantly, value per tonne processed are significantly higher than [what was] achieved by the old plant configuration, and at target volume levels will place Kareevlei in a healthy cash flow positive position,” the miner added.

The price per carat of diamonds sold in the April tender period has been estimated at over $500, compared with the previous average of $293.

BlueRock highlighted that it would now also focus on several new opportunities, having recently entered into detailed discussions regarding a previously unmined kimberlite prospect.

CEO Adam Waugh said that while it was still early days and there was limited data to provide greater detail, the company was encouraged by its production results and recovery to date.