Modern Mining: Featured News

Spurred on by a tin price that is already very healthy (US$21 600/tonne as of early March) and set to possibly go even higher, several junior mining companies are pursuing tin projects around Africa. Among them is AIM‑listed AfriTin, which has an 85 % interest in the past-producing Uis tin mine in Namibia. AfriTin’s Chief Executive Officer, Anthony Viljoen, says the company intends bringing Uis back into operation later this year. “Initial production will be on a small scale but our intention is to upscale to 5 000 t/a of tin concentrate within several years,” he recently told Modern Mining.

The Uis project, which comprises three separate mining licences, is located 220 km north of the Port of Walvis Bay in Namibia’s Erongo region (and close to the famous Brandberg Mountain). Although the tin mineralisation at Uis was discovered in 1911, it was only in the early 1950s that a commercial-scale mine was established at the site. This was acquired by Imcor (a subsidiary of Iscor) in 1958. Imcor started operations with a 35 t/h extraction plant which was enlarged in 1966 and then again in 1980 to an eventual capacity of 140 t/h. The mine continued to produce through to 1990 when it was closed due to a collapse in the tin price.

Afritin Aerial 1

Aerial view of the Uis mine. It was reportedly the largest hard-rock tin mine in the world at one stage.

“In its day, Uis ranked as the largest hard-rock tin mine in the world,” says Viljoen. “Annual tin production was as much as 1 500 tonnes, which was very substantial for that era. Since the closure of the mine, there have been several attempts to re-establish operations but none of them succeeded. We aim to break that pattern. We have a clear strategy to revive Uis and we should be selling our first concentrates within the next few months, making us the first of the new crop of aspiring African tin producers to enter production.”

The grade of the Uis deposits is very low but this is balanced by the fact that opencast mining methods can be employed. “Most tin production globally is either from high-cost underground mines, which account for around 60 % of production, or from alluvial operations,” Viljoen explains. “Once we’re in operation, we will be one of only a relatively few open-pit tin mines globally and, in fact, will be comparable in many respects to the Pitinga mine in Brazil, currently the world’s biggest open-pit tin mine. We will also benefit from an orebody that is exceptionally coarse-grained, which makes for very low comminution costs and a simple process flowsheet.”

Viljoen also points out that the Uis project is located in one of the most stable mining jurisdictions – indeed, one of the most stable countries – in Africa. It is in an area served by excellent infrastructure, with a deep-water port – Walvis Bay – within easy reach. Moreover, mining skills are plentiful within Namibia and the country has a very competent engineering industry accustomed to providing support to the mining sector.

Uis represents the flagship project of AfriTin, which was created last year to house tin assets previously owned by AIM-listed Bushveld Minerals. AfriTin was incorporated in September 2017 and listed on AIM in November, having successfully raised £4,5 million (£3,5 million in equity and a further £1 million in convertible loan notes). Apart from the Uis project, AfriTin also inherited the Mokopane tin project in South Africa from Bushveld.

The Uis tin mine is located within the Uis pegmatite swarm. The primary mineral is cassiterite (SnO2), with secondary tantalum, niobium and lithium. A mine planning report compiled in the late 1980s by SRK identified reserves of 73 Mt at 0,136 % Sn (with an additional 2,7 Mt at 0,015 % Ta2O5) containing just over 95 000 tonnes of tin. “The SRK figures are not compliant with modern reporting codes and we are in the process of preparing our own mineral resource estimate but clearly we have a substantial deposit,” says Viljoen. “Moreover, there is a strong possibility that we could exploit the secondary minerals to enhance the economics of the project.”

He stresses the exploration upside at Uis. “Imcor’s mining operations were extensive and saw mining taking place in about 12 separate pits. Nevertheless, there is still huge scope for exploration as there are many virgin pegmatite outcrops across our mining licence area which were never evaluated in the past. Imcor exploited only a small part of what is a vast area of mineralisation.”

Most of the infrastructure of the old mine has either been removed or is in a state of disrepair, so AfriTin is essentially having to start from scratch at Uis. “Currently, we have a small 3 t/h pilot plant on site which we’re using for metallurgical testing. We are, however, in the process of building our Phase 1 plant which will allow us to produce up to 780 tonnes of tin concentrate per annum,” says Viljoen.

“Next year, we will start on our Phase 2 plant, which will be a full-scale facility able to treat 3 Mt/a ROM. We envisage that this will be commissioned in 2020, enabling us to start a ramp up to a steady-state production level of 5 000 tonnes per annum of a 65 % tin concentrate.”

AfriTin has already made good progress in procuring equipment for the Phase 1 plant, announcing in January this year that it had purchased the entire front-end crushing component required through its Namibian subsidiary, Dawnmin Africa Investments. The equipment includes a jaw crusher, three cone crushers, stacking and conveying equipment and electrical switchgear.

It also announced that it had appointed Crushplant & Utility Spares, a Namibian-based engineering firm specialising in the construction and installation of crushing equipment, to match the equipment to the required specifications and prepare it for installation at the mine site.

Comments Viljoen: “This equipment represents the entire comminution circuit for the Phase 1 plant. In addition, we’ve purchased two DMS units, which are currently in South Africa and awaiting delivery to site. All these components – which collectively represent about 60 % of the Phase 1 plant – have been purchased second-hand at extremely good prices.”

He adds that the process route being adopted by AfriTin is based on the flowsheet used by Imcor. “They used a simple gravity process using jigs, spirals and shaking tables. The only real change that we’re making is that we’ve elected to use DMS units rather than jigs. We’re also looking at some form of pre-concentration of the ROM material. At the moment, we pre-sort – quite successfully – by hand but this would not be appropriate for the larger ROM tonnages we ultimately envisage.”

Turning to the mining of the ore, Viljoen says AfriTin envisages a straightforward open-pit operation using standard drilling and blasting and load and haul methods. “The tonnages we need to move, even for the Phase 2 plant, are not huge and the envisaged strip ratio is very low so essentially we need only a relatively small fleet of excavators and articulated dump trucks,” he states. “Historic mining revealed no problems with pit slopes or groundwater. Initially, we’ll concentrate on exposed ore zones within the old mining footprint.”

The initial focus of mining is likely to be the V1 and V2 pegmatites. AfriTin has completed detailed geological mapping of the two pegmatites and developed a 3D geological model. The model provides an outline of the V1 and V2 orebodies extending to a depth of 150 m and will be utilised to generate a block model from which a provisional mine production plan will be produced.

To implement the Uis project, Viljoen is assisted by a small but highly experienced team. Its members include mining engineer Frans van Daalen, who is COO of AfriTin (and a co-founder and current director of well-known mining consultancy VBKom), electrical engineer Michiel Odendaal, with 40 years of experience, exploration geologist Timothy Marais, who has worked on projects across Africa, and metallurgist Jan Rabe (the founder of TrueGround Consulting, a process engineering consultancy).

AfriTin is partnered in the Uis project by the Small Miners of Uis (SMU), a mining co-operative established by Namibia’s Ministry of Mines & Energy in the 1990s. The SMU holds 15 % of the project.

The ultimate success of the Uis project will depend on the tin price remaining healthy. The metal has a history of price volatility (over the past 20 years it has ranged from as low as US$3 880 in 2001 to as high as nearly US$33 000 per tonne in 2011) but Viljoen is confident that the outlook is very positive.

“Tin is a ‘green’ metal that is absolutely crucial to modern technologies. Most notably, it has replaced lead in solder alloys and is also an important constituent of lithium-ion batteries. As a result, global demand has been steadily increasing year by year. Mine production has not kept pace and this has resulted in the price moving up sharply over the past couple of years. The global deficit in supply is expected to continue so our project is very well-timed. It will re-establish Namibia as a significant world producer of tin and also provide a platform for AfriTin to achieve its stated goal of becoming the ‘Tin Champion’ of Africa,” he concludes.

Report by Arthur Tassell, photos courtesy of AfriTin.

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Title: Editor
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Email: mining@crown.co.za
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