Endeavour Mining is well advanced with a US$290 million expansion that will result in the refractory ore from the Massawa deposits being integrated into the Sabodala-Massawa mining complex’s production profile.
Endeavour Mining’s COO, MARK MORCOMBE, recently responded to questions put to him by ARTHUR TASSELL on the rationale for the expansion, the progress being made and what the project will mean for the group.
The project, located in southeastern Senegal, will result in the full incorporation of the Massawa refractory deposits into the Sabodala-Massawa mining operation. This will result in the Sabodala- Massawa complex becoming a Tier 1 gold producer with an annual production of over 400 koz at a low AISC of US$745 per ounce.
The Massawa property is located approximately 30 km to the south of Sabodala. The Sabodala mine, the cornerstone of the complex, ranks as Senegal’s first large-scale gold mine and has processed well over 50 Mt of freemilling gold ore since its start-up in 2009.
The mine entered the Endeavour portfolio in 2021 when Endeavour acquired Teranga Gold. As part of the deal, Endeavour also inherited the unexploited Massawa deposits. Originally a Randgold Resources project, Massawa was acquired by Teranga in 2020 from Barrick Gold, which had merged with Randgold Resources in early 2019.
The expansion is expected to yield incremental production of 1.35 Moz at a low AISC of US$576/oz over its life of mine (through to 2033). Sabodala-Massawa currently has 4.1 Moz at 2.02 g/t Au of proven and probable reserves, 6.3 Moz at 1.86 g/t Au of measured and indicated resources and 1.4 Moz at 2.16 g/t Au of inferred resources. Of the M&I resource, 4.2 Moz, or 66%, is classified as non-refractory material while 2.1 Moz, or 34%, is classified as refractory and will be processed through the new BIOX® expansion.
According to Morcombe, the expansion project boasts very attractive economics. “At a US$1 700 gold price, the project has a post-tax 72% IRR and a payback period of just over a year, which improves significantly at higher gold prices,” he says.
“Of the initial capital cost of US$290 million, 84% had been committed by 9 November 2023 with pricing in line with expectations. I am really pleased with the progress made on the project, which remains on budget and on track to start up in the second quarter of 2024.”
He adds that the expansion will add to and diversify Endeavour’s already high-quality portfolio of mines in West Africa. Apart from Sabodala-Massawa, these are Houndé and Mana in Burkina Faso and Ity in Côte d’Ivoire. Between them, they are expected to produce between 1.06 Moz and 1.13 Moz of gold in 2023 at an AISC of between US$895 and US$950/oz.
They will be joined soon by the new Lafigué mine in Côte d’Ivoire, currently under construction at a cost of US$477 million, which is scheduled to enter production in Q3-2024. Discussing the need for a BIOX® plant, Morcombe points out that refractory gold is simply gold that is hosted within the sulphide lattice and needs to be pretreated before it can be processed by conventional CIL processing.
“There are several pre-treatment options available such as BIOX®, pressure oxidation, or roasting. We chose BIOX® as it proved to be the most viable,” he explains.
“The technology was developed by Metso-Outotec and has been a commercially viable technology for over 30 years with over 24 Moz of gold recovered globally since its adoption.
“Pressure oxidation (using autoclaves) was considered as part of earlier studies but given the remoteness of the operation, the relatively small inventory of refractory material and the capital intensity and complexity of the pressure oxidation process, the studies concluded that it was not a commercially viable and technically appropriate process.
BIOX® technology
“The BIOX® technology is designed and operated under licence from Metso-Outotec and has been designed to dissolve >95% of the sulphide minerals, thereby liberating the associated gold, and we are expecting recoveries above 90%.”
Low-capital brownfields project
The Sabodala-Massawa expansion, essentially a low-capital brownfields project, involves the construction of a 1.2 Mtpa BIOX® plant that will process the high-grade refractory ore from Massawa. It will supplement the current 4.2 Mtpa carbon-in-leach (CIL) plant at Sabodala which will continue to process non-refractory ores.
A new Tailings Storage Facility (TSF) will also be built. It will be a fully HDPE-lined storage facility designed to host the neutralised product from the BIOX® reactors and the BIOX® CIL tailings. It is designed to accommodate a total of 1,0 Mt of tailings.
ALSO READ:
Endeavour Mining triples indicated gold resource at Tanda-Iguela
Morcombe notes that Endeavour has dedicated in-house expertise to manage BIOX® technology and will have Metso- Outotec consultants on site during the first year of start-up to ensure ramp-up to plant design.
“Earlier in my career I was operating one of the biggest BIOX® plants in the world at the Obuasi mine in Ghana and we have a strong BIOX® bench strength within both our operating and projects team,” he says.
“Our project director building the expansion designed and built the Jinfeng BIOX® plant and did the study work at the Runruno project, our plant manager was at the Bogosu BIOX® plant, our deputy plant manager was also at Obuasi and our process lead has worked at Jinfeng, Runruno, Obuasi and Fosterville, so we have built up a strong and experienced team.”
Explaining the rationale for locating the BIOX® plant adjacent to the existing CIL plant, Morcombe says it will allow Endeavour to reduce costs and improve efficiencies by sharing infrastructure.
“Ore from the Massawa property will be transported approximately 30 km by road to the Sabodala processing facilities,” he states.
“However, refractory ore will be treated in an entirely separate circuit from the CIL circuit with no mixing of streams. That said, there are several shared services that we can leverage between the two processing circuits, namely the power station as well as other auxiliary buildings. Using these existing facilities reduces the capital and operating costs of the project, ultimately boosting the return.”
Apart from Metso-Outotec (which has also supplied equipment packages to other Endeavour projects such as Houndé and Ity), other major contributors to the Sabodala- Massawa expansion include the EPCM contractor, Lycopodium, a long-time partner of Endeavour, and Wärtsilä, which is undertaking an 18 MW expansion – comprising three 6 MW HFO generators and two backup diesel generators – of the current 36 MW HFO power station at Sabodala. Concrete and civil construction works have been awarded to a local Senegalese contractor.
Open-pit mining On the subject of the open-pit mining at Sabodala-Massawa, Morcombe describes it as a straightforward operation which uses conventional drill and blast methods. The current mining fleet, which is owned by Endeavour, includes approximately 70 mobile mining equipment units with the capacity to move over 50 Mtpa of ore. Units deployed include PC3000- 6 face shovels, PC1250 excavators and HD- 787-7 dump trucks, all
Komatsu machines, and Cat 777E dump trucks. The mining is undertaken in-house although surface ore haulage and blasting is outsourced to a specialist contractor. Drilling is carried out by a combined owner and contractor drilling fleet.
“Mining activities in 2023 were undertaken across several pits,” says Morcombe. “We have a high degree of flexibility at Sabodala-Massawa as we are able to source oxide materials from many active mining areas. For example, in 2023, ore was sourced across the Sabodala, Niakafiri East, Kiesta, Delya, Sofia North extension and Bambaraya pits, with some supplemental highgrade material being provided by the Massawa North Zone pit.”
Solar facility An interesting development at Sabodala-Massawa is that Endeavour has made the decision to build a 37 MW photovoltaic solar facility and 16 MW battery storage system to complement the existing power plant. The Kedegou region, where the Sabodala-
Massawa mine is located, boasts a high solar resource of 2 130 kWh/m2 per year and suitable land, with a footprint of over 51 ha, has been secured approximately 3 km away from the mine. The capital cost of the project – which will allow operations to function with only one generator active during clear sky days – is US$55 million and commissioning is expected in Q1-2025.
Dornier Suntrace, an independent solar energy solutions expert based in Germany, has been contracted to engineer and support the construction of the solar system. Design work, geotechnical studies and the procurement process are all progressing to plan and the project is on schedule and on budget.
“The solar plant will be our first venture into solar and a key contributor to our emissions reduction strategy as it is expected to help lower our carbon dioxide emissions at Sabodala-Massawa by 46 kt of CO2 emissions, or roughly 24% of the site’s current emissions, thereby helping us to meet our group 2030 emission reduction targets,” says Morcombe.
He adds that Endeavour is hoping to explore solar opportunities at its other operations across the West African region.
Morcombe emphasises that there is tremendous exploration potential at Sabodala-Massawa, which could extend mine life considerably.
“The exploration land package is a large area which covers over 1 240 km2,” he states.
“We are on track to meet our ambitious target of discovering 2.3 to 2.7 million ounces of indicated resources at Sabodala-Massawa over the 2021 to 2025 period at a low discovery cost of less than US$26 per ounce.
“The current focus area for exploration is in the Niakifiri area to delineate extensions and further high-grade oxide ore pockets and to further understand the opportunity for future underground potential across the Kerekounda- Golouma complex and the Massawa zone.”
Senegal’s stable mining code Finally, and on the subject of Senegal as a mining destination, Morcombe points out that the country is a member of the Economic Community of West African States (ECOWAS) and the West African Monetary Union (WAEMU).
“The country shares a common currency and central bank with the other WAEMU members, including Côte d’Ivoire and Burkina Faso, which means the fiscal and monetary policy, as well as mining policy, are very well aligned across these countries, making it easy for us to operate in the region.
As a result, Senegal has a stable mining code and deploys standard tax principles that are consistent across the region and aligned with guidance from the IMF,” he states. “Overall, Senegal is a stable, mining friendly country to operate in and we operate closely with our partners in the region to provide a positive impact to our host communities and governments.”