JOHANNESBURG (miningweekly.com) – Johannesburg- and New York-listed Sibanye Gold on Monday declared a 46% hike of its mineral reserves that would “significantly” enhance and extend the gold producer’s life-of-mine (LoM) production profile.

The group’s economically extractable gold mineral reserves had increased to 19.73-million ounces by December 2013, up from the 13.5-million ounces recorded as at December 2012.

Sibanye’s total uranium mineral resources, which were not considered in 2012, amounted to 68.81-million pounds, including 43.16-million pounds of uranium mineral reserves.

However, the group’s gold reserve grades remained at similar levels, while Sibanye’s total attributable gold mineral resources declined 13% to 64.96-million ounces.

The drop in mineral resources was partially offset by the inclusion of 1.14-million ounces of gold contained in the newly declared mineral resources at the Beisa reef section, at Beatrix West, in the Free State.

Sibanye noted that lower pay limits resulting from operating cost reductions, improved mining quality factors and an 8% increase in the assumed gold price to R410 000/kg had allowed the inclusion of 0.93-million ounces of additional mineral reserves from secondary reefs.

“A comprehensive review of all unmined areas across the operations (white areas) resulted in the inclusion of an additional 2.85-million ounces in the mineral reserves,” the gold producer said.

Mineral reserves at the Driefontein and Kloof operations, both west of Johannesburg, increased to 1.69-million and 6.02-million ounces respectively on the back of detailed investigations into the economic potential of white areas, which were not previously considered in the LoM plans.

The respective 39% and 4% rise in reserves at Driefontein and Kloof was also the result of secondary reefs becoming available following an 8% and 10% decrease respectively in the overall pay limit.

Further, a prefeasibility study on the Driefontein 1 shaft pillar saw the inclusion of another 490 000 oz.

Studies were ongoing and further additions from secondary reefs and white areas were likely in the future, the company pointed out.

The total mineral reserves also included the addition of 4.02-million ounces of gold contained in the tailings storage facilities at the Kloof and Driefontein operations that would be mined as part of Sibanye’s West Rand Tailings Retreatment Project.

The mineral resources at Driefontein decreased by almost 1-million ounces to 21.25-million ounces, while the resources at Kloof fell 24% to 30.38-million ounces.

Meanwhile, the Beatrix operation reported an 8% rise in mineral reserves to 3.63-million ounces, owing to a 10% decrease in the overall pay limit and the inclusion of additional white areas in the new LoM plan. Gold mineral resources at the mine increased 10% to 9.31-million ounces.

Sibanye also declared a 25.66-million-pound uranium mineral resource at the Beisa section of Beatrix West for the first time, following the successful conclusion of a concept study that investigated the economic potential of mining uranium and gold from this section.