High in the mountains of northern Peru lies the La Arena open-pit mine, a combined gold and copper operation. The site sits along one of the world’s largest porphyry copper–gold belts, part of the Andean metallogenic area that has yielded many of South America’s major deposits. As of late 2024, the mine is owned by Zijin Mining.

The geology at La Arena is notably abrasive, with hard volcanic and intrusive formations that place significant stress on drilling equipment. These ground conditions make controlled blasting especially important, and the mine relies on pre-splitting to define stable walls and predictable bench geometries. Pre-splitting involves drilling a precise line of holes ahead of the main blast, creating a clean fracture plane that limits overbreak and improves overall pit stability.

Pree-splitting at La Arena is performed by Spanish company Acciona, a global infrastructure and mining contractor. Acciona uses 4” Down the Hole hammers paired with 5” bits. Because of the highly abrasive rock, tool life has been a long-standing challenge, prompting Acciona to run a series of comparative tests to identify equipment that could best withstand the conditions.

In mid-2025, Acciona invited Robit to participate in the tests. The setup included the Robit® H4 Marathon hammer with a TD40 shank, along with three different sets of drill bits. Robit’s DTH Drillmaster, Renato Castro, supervised the trial on site, ensuring proper operation, monitoring wear, and gathering performance data. The test period ran from June to July 2025.

The results were decisive. The Robit H4 Marathon hammer achieved a total service life of 4,740 drill meters, significantly outlasting the competitor, which reached 3,100 meters.

Bit performance showed the same trend. In the extremely abrasive rock, Robit’s bits averaged at 140 meters, while competitor bits averaged around 65 meters. Among the designs tested, the convex-face bit with Extreme Carbide gauge inserts delivered the best balance of durability and penetration.

Encouraged by the results, Acciona is exploring additional bit designs with Robit, including Extreme Carbide models, to further reduce cost per meter and improve productivity. The Marathon hammer has already convinced the contractor with its longer lifetime and penetration rates about 30% faster than the competing product.

For Robit, the successful trials represent a promising technical outcome – and the foundation for a potential long-term collaboration.

In 1987, some 30 kilometres north of Sodankylä in Finnish Lapland, prospectors made a promising discovery: their rock samples contained nickel and copper. It soon became clear that this Kevitsa ore find was one of the largest ever made in Finland. 

In the 1990s and early 2000s, the mining rights for the deposit changed hands several times. Actual mining did not begin until 2012. Since 2016, the Kevitsa open pit has been owned by the Swedish company Boliden. In 2024, it processed almost 10 million tonnes of ore, primarily nickel and copper, as well as cobalt, platinum, palladium, and gold.

Today, Boliden Kevitsa’s polymetallic mine is one of the largest in Finland. It provides direct and indirect employment for hundreds of people in Lapland and generates significant tax revenues for the region. Production is expected to continue well into the 2030s.

Responsible metal production in Arctic conditions The strategy of the Swedish metals company Boliden revolves around responsible mining, circular-economy solutions, and the production of critical metals for the green transition. Boliden Kevitsa’s polymetallic mine is an integral part of this whole.

The bedrock at Kevitsa is demanding in all respects. The rock is both tough and extremely abrasive, says Juha Ranta, Drilling Development Coordinator at Boliden Kevitsa.

“The mixture of various ore zones, wall rock, and waste rock has formed over thousands of years. Alongside the copper and nickel, there is cobalt, platinum, palladium, and gold, and each zone behaves differently when drilled,” Juha explains.

The natural conditions in Sodankylä don’t make mining any easier either. “In winter, the groundwater in the pit is completely frozen. The hammer must operate just as reliably at -40 degrees as it does at +35 degrees in the summer. That’s a tough combination for any equipment,” Juha says.

Technologically, Kevitsa is a state-of-the-art mine. Production drilling is conducted almost entirely by remote control. From the control room, operators monitor the drill rigs working in the pit around the clock.

An unmanned drill rig plus two men – Kimmo Kangas, left and Juha Ranta.

Testing and developing Robit’s H8 DTH hammer together 

Since early 2025, Robit’s H8 DTH hammer has been tested and developed at Kevitsa in close cooperation with Boliden, says Robit Sales Director Kimmo Kangas.

“The feedback from the operators has been encouraging: the H8 is easy to drill with, penetration rate is good, and durability looks promising,” Kimmo says.

The H8 hammer has been tested with two different 229 mm drill bits to optimize the combined performance of hammer and bit for Kevitsa’s conditions.

The H8 is by no means the first hammer to be tested in Kevitsa’s demanding rock. Tools that perform well elsewhere have often revealed weaknesses in Lapland. “Here, for example, rock hardness and the way the impact energy bounces back from the rock can be very different from what you encounter in other mines,” Juha notes.

Cooperation with Robit’s product development team has been close. “Whenever we’ve found a component that doesn’t last, we’ve sat down together to decide what to do about it. Do we change the material or redesign the part completely? Recently, we’ve focused on improving the hammer’s wear life, first the ‘innards’ and now increasingly the durability of the hammer body,” Juha says.

At Kevitsa, the “Marathon” version of the H8 hammer is in use, featuring a wear-protected outer casing. The goal is to extend service life and reduce both downtime and spare part consumption.

A step towards more economical and sustainable mining 

Boliden works systematically towards environmentally friendly and cost-efficient mining. “The drilling tools are one part of that. With the right tooling, you can achieve substantial cost savings, both in the equipment itself and in fuel efficiency,” Juha points out.

“Equipment durability and reliability have a direct impact on cost per drill meter. As wear resistance improves, material flows – and therefore costs – go down.” 

“New surface treatment methods also allow us to make the materials more wear-resistant. Reliability improves when components that have proved weak are reshaped and redesigned.” Testing the H8 hammer at Kevitsa is part of this overall effort. “With measures like these, we keep moving towards economical mining, with green values firmly in mind,” Juha Ranta concludes.