The underground mining sector in Portugal is climbing up the European equipment automation ranks, with Boliden’s recently acquired Somincor mine in Neves-Corvo being one of the frontrunners.
Nestled in a pocket of the country that many of Portuguese workers think of as remote – in Alentejo province, southern Portugal; roughly a two-hour drive from Lisbon – Somincor is one of Europe’s biggest zinc producers.
It is located on the renowned Iberian Pyrite Belt, having a deposit that has copper, zinc and lead. The operation was mining up to five orebodies at any one time when IM visited in late February, with the deepest going down to around 1,000 m below ground.
The asset only came into the Boliden fold last year along with the Zinkgruvan mine in Sweden as part of an acquisition of Lundin Mining’s European assets in a deal that could rise to around $1.6 billion, yet the Sweden-based company is already starting to imprint its DNA on the Somincor operation.
It drafted in Gunnar Nyström as General Manager, who moved over from the Tara mine in Ireland.
Nyström has been keen on getting closer to the core of the operation. When IM visited, he had just relocated some of the support functions closer to the mine, signifying the importance he placed on being seen and being always engaged with the operational part of the mine.
“This wasn’t a big move, but I felt it was important to let all the workers know that I am taking a keen interest in all aspects of the operation on a day-to-day basis,” he told IM.
One of the aspects that will remain in place for the foreseeable future at Somincor is the tight community relations with locals, the predominance of local employees and strong focus on environmental, social and governance initiatives.
Gonçalo Pernas, Head of the Communication and Social Responsibility Department at Boliden Somincor, explained: “We are by far the biggest employer in the region and have established an honest relationship with the nearby community. We will continue to foster this as mining progresses.”
Metal recovery roadmap
And mining looks like continuing for some time, with Nyström referencing a recent life of mine plan that has operations running until 2041. “We will need to address the tailings dam capacity before this point,” he said. Nyström said there were plenty of options on the table for pushing the life of the facility out past 2032.
The tailings benefit from a “semi-dry” stacking deposition technique, which aligns nicely with the operation’s ongoing focus on efficient water recycling. More than 95% of the site’s industrial water is currently reused, meaning it pulls very little from its local water source.
Around 50% of the tailings head back underground as backfill, with Nyström keen on increasing this percentage while also upping the utilisation of the existing paste plant at site. “At the moment, we are using a mixture of paste from this plant and hydraulic sand we purchase,” he explained. “I would like to see more of our own paste used in the backfill composition going forward.”
Currently, ore is extracted through the underground shaft system and dispatched to the corresponding copper or zinc “ore park”. In the case of copper ore, material is further classified into two categories based not only on geological type, but also on the concentration of penalty elements.
Stockpile management and surface blending are carried out to ensure compliance with the required plant feed grade specifications. The blended ore is reclaimed by wheel loader and fed into the crushing and pre-screening circuit, after which it is transferred to a buffer silo supplying the two grinding lines of the copper plant. The comminution stage consists of two parallel rod mills (one per grinding line), followed by two inter-mixable primary rod mills operating in closed circuit with two cyclone batteries. The cyclone overflow from the two lines is combined and sent to a secondary classification system operating in closed circuit with a secondary ball mill. The final overflow from this circuit constitutes the feed to the flotation stage.
Froth flotation is carried out in a conventional circuit comprising rougher flotation, followed by regrinding of the rougher concentrate, and subsequent scavenger and cleaner stages. A retreatment circuit is in place to process both the coarse and fine tailings from the main flotation circuit. This retreatment circuit produces a secondary copper concentrate with lower copper grade and higher penalty element contents, as well as a zinc concentrate that is blended with the concentrate produced in the zinc plant. In this circuit, regrinding is performed using an IsaMill from Glencore Technology to achieve the required mineral liberation.
In the zinc plant, the crushing and pre-screening stages, along with the rod and primary mills, were replaced by the SAG mill commissioned in February 2022. The SAG mill operates in closed circuit with the primary cyclones. The primary cyclones overflow feeds a “trash screen” that removes coarse particles and process debris. The screened product is then directed to a secondary classification system operating in closed circuit with a Vertimill from Metso. The overflow from this circuit constitutes the feed to the differential flotation circuit for lead and zinc currently used in the zinc plant.
Both the lead and zinc circuits include rougher, scavenger and cleaner stages, followed by column flotation in the lead circuit. The lead rougher tailings stream is routed to the zinc flotation circuit. In the zinc circuit, regrinding is carried out in a regrind Vertimill.
All concentrates are thickened in conventional rake thickeners and filtered using filter presses. The copper and zinc concentrates are transported by rail to Setúbal, while the lead concentrate is shipped by truck to Sines.
One of the focus areas for the plant has been on improving recoveries, Nyström said, with upcoming trials to look at the potential impact of thiosulphates and pyrite in the processing water during flotation, plus the options for grinding down to a finer fraction to boost metal recoveries. “We have an SMD (Stirred Mill Detritor) test unit on site that we are planning to leverage from March for some of this fine grinding test work,” he said.
The company also benefits from an on-site, ISO 17025-certified analytical laboratory that can carry out metallurgical test work using X-ray Fluorescence technology for not only the Somincor operation, but other mines.
Pushing new limits
It is underground where the company is really pushing the limits.
Drift-and-fill and bench-and-fill stoping are the primary methods in operation at the site, with both methods now well adapted and tailored to the large but locally complex high-grade ores present throughout the operations.
Underground operations already benefit from LTE infrastructure installed underground in 2023; this replaced the Wi-Fi network that was installed in 2021. The shift has allowed it to, among other things, up the automation ante when it comes to loading and drilling and keep a closer eye on personnel and vehicles.
The maze-like configuration of the mine and need to mine up to five orebodies mean there are more than 40 pieces of heavy equipment to call on. All this equipment, serviced via three underground maintenance workshops, is fitted with Mobilaris beacons that can be tracked from the control room on surface. All personnel have Mobilaris phones that are equipped with RFID technology for tracking.
The production support and ancillary fleet includes several Normet machines, with the production fleet having a split of the traditional yellow and orange equipment, much of which can be automated.
Somincor has three Epiroc Scooptram ST18 loaders to call on, all of which are connected to the OEM’s Deep Automation platform. These loaders – along with a fleet of Sandvik Toro® LH621is – deliver material to several Epiroc Minetruck MT65s. Nyström mentioned that the operation is expecting the delivery of four Sandvik Toro TH663is later this year or next year to bolster trucking operations.
When it comes to longhole drilling, the company initially experimented with Sandvik Solo rigs in teleremote mode, yet the change to LTE infrastructure in 2023 necessitated a shift to Epiroc Simbas for more automated drilling – especially for uphole drilling.
“We got the Simbas in late 2024/early 2025 and, in our first full year, carried out just under 10% of drilling in automated mode,” Nyström said. “We are pushing for much higher this year, which will be helped by newer Sandvik longhole rigs arriving to replace the older Solo rigs.”
The complications of automating a mixed fleet are felt most acutely on the loading side of operations, with two systems currently being utilised – Deep Automation for the Epiroc LHDs and AutoMine® Multi Lite for the Sandvik loaders.
Both systems are allowing continuous operations during blast clearance and shift changes, but the need to install two separate barriers for the different automation zones is not a practical or effective way to further refine autonomous loading operations.
Even with this hurdle in place, Nyström reported some punchy automated stope mucking numbers in late February: “In January, 64% of the stope tonnage mined was automated from the Automation Room on surface. Overall, in 2025, it was 42%, or some 1.13 Mt.”
In the future, the company could also consider carrying out automated trucking underground, with Nyström referencing the nearby (35-40 km) Aljustrel mine owned by ALMINA as an example to follow.
“We have a great relationship with ALMINA, so have seen the success of the automation program there,” he said. “They can carry out ore loading and haulage autonomously from the extraction point, all the way up the underground ramp and break through at surface before dropping off at a stockpile – all without an operator in these vehicles.
“We view this as a good example to follow.”
Teleremote mucking during shift changes in development stopes is another area of interest for the mine, Nyström says, especially considering the mineralisation continues to extend at depth where, at the height of summer, rock temperatures can reach up to 55°C.
It is this fact that has the company looking to double ventilation capacity with two new shafts, as well as increase its captive power supply.
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