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With the global demand for tin (Sn) on an upward trajectory as the energy transition kicks in, the emergence of a new tin province in central Africa is good news for a market besieged by instability.
While headwinds continue to batter established tin operations, there is an acute shortage of the white metal as junior miners struggle to get their greenfield projects up and running.
One mine that has been firing on all cylinders over the last two or three years is Alphamin’s Bisie Complex in the Democratic Republic of the Congo (DRC). Not only does Bisie now produce 4% of the world’s tin, but the mine is extracting ore at its Mpama North mine at mind-blowing grades with an average of 4% and higher.
The mine recorded contained tin production of 3,104 tonnes for the quarter ended September 2023 which is in line with the previous quarter. Tin production of 9,442 tonnes for the nine months ended September 2023 exceeds the run rate to achieve market guidance of 12,000 tonnes for the year ending December 2023.
The run-of-mine and crushed ore stockpiles ahead of the processing plant were at record levels at quarter-end, being 30,393 tonnes at an average tin grade of 4,79% (Q2: 27,439 tonnes at 6.74%).
Sales volumes of 3,111 tonnes of tin for Q3 2023 were slightly higher than the previous quarter and averaged a tin price of US$26,557/tonne (Q2 2023: US$25,587/tonne).
Investing in exploration
Besides mining at a frenetic pace, Alphamin has been investing heavily in exploration over the last 24 months, not only to drill out the Mpama South ore body but also to extend and expand Mpama North and more targets in between these tin occurrences.
What has become clear during the exploration program, is that the Bisie Complex forms part of a possible new tin province. Alphamin tenements are central to this large complex, but more artisanal activity and one or two new exploration outfits testing the water close to Alphamin on the extended Bisie ridge is an indication that Mpama South is certainly not the end of the road. In fact, it might just be the beginning as Alphamin starts digging deeper and ups the ante in its exploration drive.
Good rocks are not hard to find
In geological circles the adage goes that “good rocks don’t lie” and that certainly seems to be the case in the thick forest of the Congo Basin where Alphamin set up shop in 2018. It’s no secret that there are pretty “good” rocks to be discovered at Bisie Hill. It is also known that the best is yet to come. But for now, all indications are that Alphamin’s geologists have stumbled upon an anomaly that could prove the Bisie Complex to be regarded as the fifth tin province in the world.
Tin provinces and Bisie’s significance
Tin provinces are one of the best examples of metallogenic provinces. According to Lehmann (2020) about 85% of all historically mined tin is sourced from four main tin ore provinces within large granite belts. These are, in decreasing importance, Southeast Asia (Indonesia, Malaysia, Thailand, Myanmar), South China, the Central Andes (Bolivia, southern Peru), and Cornwall, in southwest England.
The Ridge at Bisie in the DRC is about 20km in length of which an extremely small area has been drilled up to now even after Alphamin’s extensive drilling program that got underway late in 2020.
When Bisie was initially developed Alphamin only drilled out a deposit of five million tonnes. The Bisie mine was designed to be a “staged rollout”, where sufficient Resources were identified to support an initial operation with an adequate Life of Mine and acceptable returns. Once operating, further drilling would be carried out with internally generated cash flow.
The result was that Alphamin discontinued the exploration program with only 40,000m drilled. The lure of Bisie was the grade though, which measured an average of close to 4.5%. In some holes, the geologists measured up to 7% Sn, which was unheard of. In the global context, that puts Bisie in a class of its own.
At that stage, the highest-grade tin mine in the world was believed to be San Raphael in Peru, which mined tin at close to 2%. Since then, the average tin grade at San Raphael has dropped to well below 1.8%. The exciting fact about Bisie is that what they found initially and then developed is only the tip of the iceberg. The current mine sits on top of a single deposit (Mpama North) located on a mineralized ridge of between 13km to 20km long.
About 750m from Mpama North lies Mpama South and further along the ridge, there are several other prospective targets. These targets all fall within Alphamin’s tenement at Bisie.
Mpama North fits the genetic model for tin deposits globally and like 99% of all tin in the world occurs in granite-associated lithologies. What makes Bisie unique, however, is that the deposit has remained intact for millions of years, in contrast to similar deposits in the world where erosion played a much greater role a lot earlier. These deposits usually occur on intercontinental margins, whereas Bisie lies in an inter-cratonic zone and is subjected to intense and repeated compression and extension.
The Bisie Ridge thus represents the contact between a granite/basement and metasediments. Mineralization occurs where northeast trending structures cross-cut this contact, evident at both the Mpama North and Mpama South deposits. This configuration is also evident at several other localities along this 13km ridge contact. Bisie is a strange anomaly in that it is a large, underexplored, extremely old, and very high-grade deposit.
Rapid development of Mpama South
While the high-grade tin continued flowing at Mpama North, Alphamin announced this week that the company had completed 2,448m in total of underground development to date at its Mpama South mine. More than 988m of development was done in Q3 2023 while the team advanced with more than 603m in Q2. The underground development rate thus increased by 64% in Q3 as more equipment was deployed during this time and additional development ends were made available underground.
In Q3 the Mpama South adit from surface successfully advanced beyond the previously reported area of poor ground conditions and Alphamin now expects it to connect with the Mpama South underground workings by early November 2023.
The year-to-date development meters at Mpama South align with the company’s updated two-year underground mine plan to achieve the targeted tin production expansion from FY2024.
This plan requires ~1,200m of underground development at Mpama South during the quarter ending December 2023. By quarter-end, Alphamin had spent close to US$99 million of cash resources on the Mpama South project of which US$24.5 million was spent in Q3 2023. The project is forecasted to be substantially completed within the budget of US$116 million.
Processing facility delayed
In a recent statement, Alphamin said that the commissioning of the new processing facility to accommodate the increased throughput from Mpama South, will be delayed by one or two months because of poor road conditions and a damaged bridge which has delayed container deliveries by almost three weeks.
The bridge on the primary export and import route was damaged in late September and according to Alphamin inbound and outbound trucks had to be re-routed, resulting in longer than normal transit times and delays in revenue receipts.
Additional road maintenance teams have been mobilized to ensure the efficient passage of inbound and outbound traffic via alternative routes which have been proven to be effective in the past. The negative liquidity impact from the damaged bridge is expected to reverse during Q4, 2023.
The Alphamin project team, together with the existing site team, remains focused on operational readiness preparation. This primarily involves recruitment and training of personnel, expansion of the laboratory and accommodation facilities and infrastructure, and increasing the supply chain to meet the additional production. The Mpama South project is expected to increase combined annual tin production from ~12,000 tonnes to ~20,000 tonnes.
