JOHANNESBURG (miningweekly.com) – Southern African diamond development and exploration company DiamondCorp has completed the first sale of diamonds recovered from tailings retreatment activities at its Lace diamond mine, in the Free State.

The sale of 6 442.04 ct earned gross proceeds of $278 574.30, representing an average of $43/ct.

The November diamond sale included the first diamonds sold to Tiffany & Co subsidiary Laurelton Diamonds under a January offtake agreement, in terms of which DiamondCorp had agreed to a term loan of $6-million in exchange for awarding Laurelton the right to buy, on commercial terms related to fair market value, production from the Lace mine.

The diamonds sold comprised 5 026.72 ct recovered prior to and during the commissioning of the Lace recovery plant, and 1 415.32 ct of run-of-mine gems recovered after plant modifications were made to increase the bottom screen cut size in the plant.

The diamonds recovered after the modifications comprised a coarser stone size distribution, achieving an average price of $63/ct, which DiamondCorp considered to be a fair benchmark for the economics of the tailings retreatment operation in 2014.   

Amid “subdued” overall diamond market conditions characterised by soft prices for small stones, the diamond developer expected that tailings retreatment operating costs could be reduced from R32/t to R22/t once three shifts were operating.

“As a result, we are proceeding with a ramp-up to a three-shift operation by the end of January next year, with plans in place to increase tailings throughput to more than 150 000 t/m in the first half of 2014 through the introduction of in-pit screening,” DiamondCorp said in a statement on Tuesday.

Should recoveries remain in the order of 5 ct per hundred tons, the in-pit screening had the potential to increase production to 7 500 ct/m, which would allow a significant proportion of the tailings to be retreated prior to the underground mine achieving full production.

Meanwhile, income from the Lace beneficiation joint venture with Distinctive Choice netted $20 361 in October, while development of the underground mine at Lace, operated by DiamondCorp’s 74%-owned subsidiary Lace Diamond Mines, was fully financed for the 47 level block cave.

“Mining remains on track and within budget. At head office, management have made extensive cost savings, which have enabled the company to defer any fundraising to cover corporate overheads until 2014,” said the miner.