The RHA underground tungsten mine, in Zimbabwe, has a forecast eight-year mine life, but a resource upgrade, which is expected to conclude in the coming weeks, should “more accurately” assess the life-of-mine (LoM).

Aim-listed Premier African Minerals CEO George Roach tells Mining Weekly that he would like to see a combination of underground and opencast mining at the mine. “When our resource evaluation and update conclude, I will be able to take better view of this.”

The multicommodity African exploration project developer reported in July that it had completed plant upgrades at its 49%-owned RHA tungsten project, which produced its first concentrate last year.

At this time, the screens, plant modifications and electrical reticulation works had been completed and the plant was undergoing a phased commissioning and optimisation process to achieve the expected recoveries and operational throughput.

The miner noted that wolframite concentrate from ore of the underground mine had been produced and that the throughput of the plant would steadily be increased to the plant’s design capacity of 16 t/h. RHA has a target mining rate of 8 000 t/m of tungsten.

Meanwhile, X-ray transmission (XRT) testwork has also been conducted on bulk sample material from RHA, which was rerun at the express direction of the equipment provider to confirm previous results.

“The equipment provider now confirms that the sort achieved a near 100% recovery. Premier is reassessing the pit capacity to meet the minimum tonnage that XRT sorting will require and expects to be in a position to progress this in early August,” Roach said in July.

Meanwhile, he tells Mining Weekly that Premier African Minerals still knows “very little” about the ultimate depth extensions at the RHA project beyond historical drilling. “One interesting feature is that concentrates from underground ore carry copper. It has been speculated that this may increase with depth,” Roach adds.

The project, near Hwange, boasts entirely local skills, with no expatriates employed at the mine, which started operations in August.

Roach says the 1 800 ha project is divided into 50 mineable mineral blocks, of which Premier African Minerals owns ten.

“Premier has an option over surrounding claims that has been exercised; however, a dispute has delayed the transfer of the claims under option. Those we hold cover the entire known mineralisation of the surrounding areas at RHA,” he states, adding that those in the option represent possible exploration targets.

The underground mine produces a wolframite concentrate that is measured in metric ton units (mtu); wolframite consists primarily of ferberite, with a smaller quantity of hubnerite, Roach adds.

Every mtu of concentrate is equivalent to 10 kg of tungsten trioxide contained in a concentrate at about 60%.

“The concentrate is sold at a discount at the ammonium paratungsten price of $185/mtu to $200/mtu. “The production of ammonium paratungsten from wolframite concentrates is a chemical process that we do not undertake,” explains Roach.

In terms of RHA’s environmental impact, he points out that during the mining of tungsten, there are no contaminants left over in the water used for the mining operation which would usually have a negative affect on the surrounding communities.

That said, the project is located far away from civilisation and it only has to deal with wild animals; “. . . none of which seem in the slightest perturbed by the mining or waste. . . . our mine dam and tailings facilities are, in fact, a source of sustenance in an otherwise very dry region of Zimbabwe”, says Roach.

Lithium Operations
Premier African Minerals has started to explore potential lithium and tantalum operations at its Zulu project, in south- central Zimbabwe.

Roach explains that these operations are still in the early phases of exploration, but have shown promise. An historical exploration project carried out at Zulu by mining corporation Rhodesian Selection Trust indicated a potential 1.4-million tons of pegmatite with a 1.4% lithium superoxide.

Premier African Minerals hopes to advance the Zulu project by conducting a further 1 000 m of trenching in the area, along with 2 000 m of core drilling, accompanied by metallurgical studies.

Roach notes that African Premier Minerals has been approached by Chinese and Japanese companies that want to buy lithium and tantalum, adding that some of the ore produced from the mines is likely to be sold to the European market.