JOHANNESBURG (miningweekly.com) – Diamond sales from tailings recoveries at Southern African diamond development and exploration company DiamondCorp’s Lace mine, 200 km south-west of Johannesburg, have reached 7 505 ct since February.

The sales for the year to date had achieved proceeds of $471 160 at an average sales price of $63/ct.

DiamondCorp, which had scheduled ten sales for the year, expected the tailings retreatment to generate positive cash flow of R9/t, considering current exchange rates, the budget grade, sales price and operating costs after the installation of the degrit circuit in May.

The Aim- and JSE-listed group said diamond recoveries for the period totalled 6 953 ct at a recovered grade of 4.64 carats per hundred tonnes (cpht) against a budget of 5 cpht during the quarter to March, with output from the Free State-based mine sourced from the oldest and lowest grade section of the dumps during January and February.

The recovered grade for March was 5.81 cpht and 5.77 cpht for April.

During the period ended March, the plant processed 149 957 t of tailings against a budget of 140 000 t.

After the 400 t/h sand screen commissioned in February failed to achieve the required performance, the company demobilised the unit and was currently installing a conventional degrit circuit with the potential to increase tailings throughput to 120 000 t/m.

The circuit was expected to be commissioned in May.

The underground development at the Lace diamond mine remained close to schedule, with underground tunnel development 21%, or 1 508 m complete, compared with the scheduled 24%, or 1 777 m, and within budget at 95% of the project’s budgeted cost a metre.

“Development rates were impacted during the period owing to mechanical breakdowns on face drilling rigs and heavy seasonal rains, which caused slippery roadway conditions on the boxcut ramp. The rains have now ceased and the rigs are again providing good availability,” DiamondCorp said.

The programme for installation of the underground conveyor belt system was 95% complete and under budget.

The fabrication of two of the eight legs had been completed, while the company had started the fabrication of the third leg.