JOHANNESBURG (miningweekly.com) – London-listed Mwana Africa has achieved steady-state production at its Klipspringer slimes retreatment project, in Limpopo, with fine diamond output more than doubling over the quarter to March.

The pan-African, multicommodity mining and development company produced 12 383 ct during the quarter under review, an increase of more than 100% on the previous quarter to December 2013, Mwana CEO Kalaa Mpinga said on Tuesday.

“This flowed from the retreatment of 16 000 t of fine residue tailings, at an average grade of 77.4 ct [for every] 100 t, from the [nearby] old Marsfontein mine,” he explained.

Mwana, which started the Klipspringer slimes retreatment project in October 2013, achieved an average price of $21/ct.

Process changes made to the plant, including screening improvements and the installation of a dense-medium separator surge bin, and the onset of the dry season were expected to result in a “substantial” improvement in throughput over the next year.

Meanwhile, gold output from the group’s Zimbabwe-based Freda Rebecca gold mine fell year-on-year, but increased over the previous quarter.

Year-on-year, gold production was weighed down by the failure of a leach tank in the first quarter, which affected mill throughput and recovery, with total gold production falling 10.5% to 58 704 oz.

However, a combination of improved milled tonnes and feed grade resulted in gold production rising by 2% during the quarter under review to 13 380 oz, compared with the 13 072 oz reported during the previous quarter.

While the hike led to a decrease in cash operating costs from $1 066/oz during the quarter to December to $1 053/oz in the March quarter, all-in sustaining costs increased 3% from $1 291/oz in the previous quarter to $1 325/oz in the quarter under review. This was the result of a 10% hike in the asset amortisation charge owing to the continuing commissioning of the tailings retreatment project pilot plant.

Production of nickel in concentrate at subsidiary Bindura Nickel Corporation’s (BNC’s) Trojan mine, in Zimbabwe, rose 9.5% quarter-on-quarter to 2 207 t. The higher tonnage mined during the March quarter marked continued progress towards a steady state of 195 000 t a quarter, while the increase in tonnes milled indicated more consistent, efficient operation of the mills.

The company reported an increase in all-in sustaining cash costs from $11 819/t to $12 220/t during the three months to March, as a result of continued production ramp-up and the shaft redeepening.

Nickel sales for the quarter reached 2 250.2 t, achieving a 1.5% increase in the average nickel price to $14 075/t.

“We anticipate that at Freda Rebecca, the current focus on mining and processing efficiencies, and at BNC, continued progress by [the] Trojan mine towards steady-state and stronger mill performance, will deliver further operational improvements for the group in the year ahead,” Mpinga said.

Meanwhile, Mwana continued to work towards the completion of a feasibility study at the group’s Zani Kodo gold exploration project, in the Democratic Republic of Congo (DRC). A resource-conversion drilling programme was currently under way – to be followed by a geotechnical drilling programme – and continuing regional field investigations.

Work at Mwana’s Semkhat copper/cobalt exploration project, also in the DRC, was also progressing as the company’s joint venture partner Hailiang prepared to kick off the second year's exploration programme, which would include six targets, with geochemistry and geophysics, followed by drilling, at the end of the rainy season.

Mwana would publish its preliminary operating and financial results for the 2013 financial year in July.