The tin-bearing gossan on the Bisie Ridge was discovered in 2002 whereupon it became the subject of widespread small-scale artisanal mining. Alphamin’s interest began in 2011, when it acquired an initial 70% interest in the Bisie Tin Project from Kivu Resources, which it later increased to 100%.
Maiden resource and feasibility study
Prior to Alphamin’s involvement there had never been a formal mineral reserve or resource delineated at Bisie. However, this changed when, in November 2013, the company reported a maiden NI 43–101 compliant inferred mineral resource of 4.0Mt at a 3.5% tin (Sn) grade containing 141,200t of contained tin (at a 0.25% Sn cut-off), with the best assay results occurring in the four deepest holes drilled. Copper, lead, zinc and silver were also present.
An initial definitive feasibility study (DFS) was completed in February 2016, which estimated that the project could produce 9,000t of tin per year over an estimated 10.5 years after an initial US$119.2m in capital expenditure. The DFS was subsequently updated and optimised to reflect front-end engineering and design and control budget estimates, such that it ultimately projected production of 152,300t of tin over a 12-year life with payback in 17 months after an initial US$126.1m in capital expenditure, resulting in a project NPV8 of US$402.2m and an IRR of 49.1%.
After a final investment decision, Alphamin secured an US$80m senior secured, non-revolving credit facility in November 2017 with Sprott, Barak and Tremont, to be provided to Alphamin Bisie Mining (ABM) – the owner of Bisie. Construction at Bisie commenced later the same year and, after slightly more than a year’s construction, plant commissioning commenced in early 2019. Just prior to plant commissioning however, it was decided to change the mining method at Mpama North to one of cut and fill, after a management review into the suitability of sublevel caving in the light of prevailing rock conditions. The change resulted in revised reserves and a revised mining schedule in addition to adjustments to operating cost assumptions, mined grades and metallurgical recoveries. Nevertheless, the mine declared commercial production later the same year, in Q319.
Teething problems overcome
While Bisie was ramping up to full production, on 30 October 2019, the logistically important Maiko Bridge at Waine-Rukula collapsed. Prior to the collapse, concentrate produced at Bisie was trucked over the Maiko Bridge en route to Kisangani and, from there, to Gerald Metals depots (based in Kampala, Uganda) and then on to Mombasa, Kenya. As a result, Alphamin incurred additional logistical costs in Q120 relating to the sale of concentrate plus additional costs (eg hiring a helicopter from South Africa to transport material across the Maiko river). In consequence, on 9 December 2019, the company accepted a trader advance of US$12.6m from the company’s offtake partner, Gerald Metals, to assist with cash flow. The advance took the form of a spot contract for the sale of US$20m of tin concentrate and was ostensibly extinguished in Q120 and then fully extinguished in Q320 after the delivery of the associated lots to the designated delivery point in Uganda.
On 15 May 2020, Alphamin concluded a private placement of US$31m, which was applied to reduce its debt balance. Concurrently, it signed an amended and restated credit agreement with improved terms. Finally, in May 2020, it settled certain third-party indebtedness of ABM, the owner of the Bisie tin mine, by the issue of Alphamin shares in consideration for a temporary loan due by ABM. Subsequently, it secured the required board and shareholder approvals from ABM to convert this ABM loan into new shares of ABM, which increased Alphamin’s equity ownership of ABM to 84.14%, with South Africa’s Industrial Development Corporation’s interest then being diluted to 10.86% and the government of the DRC’s interest remaining at 5%.
Coronavirus pandemic circumvented
With the exception of some early logistical disruptions (eg along the trucking routes between Kenya and Uganda), it is worth noting that Africa, in general, and Alphamin, in particular, were barely affected by the coronavirus pandemic of 2020–22, with management reporting that East African countries reacted in a manner appropriate to the crisis that was proportionate to the risks and that the logistical supply routes between the DRC and Mombasa continued to operate in an orderly and efficient manner. As a result, mining at Bisie continued, to all intents and purposes, without disruption, allowing the company to become net cash positive in Q321 and to pay a maiden dividend to shareholders for FY21 early in FY22. It subsequently fell into a pattern of declaring interim and final dividends during FY22 (all of which have been at a level of C$0.03/share to date).
Process plant optimisation
To manage fine and ultrafine tin losses in circuit (identified at the time of the plant’s commissioning in 2019), a decision was taken to install a fine tin recovery circuit in mid-2021, which acted to improve both the plant’s metallurgical recoveries (by c 5.5 percentage points) and its throughput rate by up to 10% (in conjunction with a process of debottlenecking).
In early March 2022, Alphamin announced a maiden resource at its second major exploration target after Mpama North, called Mpama South, plus the results of the preliminary economic assessment (PEA). The PEA indicated that a mine at Mpama South could produce 7,232t contained tin per year from 468kt ore processed at a grade of 2.21% and a metallurgical recovery of 70% for a capital outlay of US$115.97m and an all-in sustaining cost (AISC) of US$15,188/t (at a tin price of US$40,000/t). Later that same month, Alphamin announced a resource upgrade at Mpama South and a decision to proceed with developing the new project.
Notwithstanding the near halving of the tin price in the second half of 2022, work commenced on the new mine. Underground development remains ongoing and on schedule and, as of August 2023, development progress is as follows:
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A total of 1,460m of underground development at Mpama South has been completed to date, of which 603m was achieved in Q223 (cf 418m in Q123). Development accelerated during Q2 as additional underground equipment arrived on site. During July 2023, the underground development connecting Mpama North and Mpama South reached the intersection point where the new Mpama South adit from surface will connect. Owing to a 6m wide area of extremely poor ground conditions, the Mpama South adit is now expected to connect with the Mpama South underground workings during November 2023, albeit this will still be in time for the tramming of ore to the new processing facility. Otherwise, year-to-date development metres are in line with the company’s updated two-year underground mine plan to achieve the targeted tin production expansion from FY24. This plan requires an additional c 2,000m of underground development at Mpama South during the six months ending December 2023, which should be achievable as additional development ends become available from Q323.
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In the meantime, the new processing facility is reported to be progressing well. Following completion of all procurement, design and engineering, fabrication, earthworks and substantially all civils, the focus has moved to plant erection and tracking of steel and equipment in transit. The fine tin plant structure, primary crusher structure and concentrate drying and storage building were erected during Q2 and the commissioning of the new processing plant remains on target to commence in December 2023, whereafter first ore is expected to be processed from late January 2024. Currently, the Alphamin project team, together with the existing site team, remains focused on operational readiness preparation, including the recruitment and training of personnel, expansion of the laboratory and accommodation facilities and infrastructure and increasing the supply chain in anticipation of additional production.
As such, the Mpama South development project remains forecast to be substantially complete within its budget of US$116m and within its expected timeframe.