Pärhä Oy’s Lokotrack® plant specializes in high-quality production of concrete gravel

Metso’s diesel-powered/electrical Lokotrack^® double-stage plant ensures that different types of crushed rock are produced effectively and economically. As a bonus, the new Lokotrack^® ST4.10™ screen operates carbon neutrally, using electricity produced by the tertiary crusher.

“Last year, we crushed more than 600,000 tons, of which some 250,000 tons were processed into different types of concrete gravel. The majority of the concrete gravel is delivered to five companies operating in the concrete industry in the Päijät-Häme region,” says Jari Pärhä, who is in charge of the crushing operations and production at Pärhä Oy.

“When such volumes are being produced by a single crushing plant, the machinery needs to be reliable. Metso is known as a dependable Finnish company that also provides well-functioning maintenance services.”

“Metso developed a Lokotrack for our needs”

The family-owned company, established by Tuomo Pärhä in 1980, shifted from forestry to the gravel business at the beginning of the 2000s. Currently, the company specializes in crushing and transportation services. Since the beginning of this year the company has three partners: Petri Pärhä is Managing Director, Jari is in charge of the crushing operations, and Tommi is taking care of the transportation arrangements.

The company acquired their first Lokotrack^® LT106™ jaw crusher in 2013, followed by a Lokotrack^® ST2.8™ mobile screen. When the company decided to focus more on crushing operations, Pärhä asked Metso for a new tertiary crushing plant. It turned out that the existing Lokotrack range did not have the right solution for Pärhä Oy.

“A few weeks later, Mikko Takaniemi from Metso came to demonstrate a raw version of the plant we were looking for. The cone crusher and screen plant included the pre-screen we had requested,” Jari Pärhä says.

In 2017, a unique diesel-powered/electrical plant, called Lokotrack^® LT330GPSE, started operating at Pärhä’s quarry in Nastola. The primary crusher was replaced by the LT120E jaw crusher, and last fall, the screen was replaced by ST4.10, a new Metso model, equipped with a 1.5 × 6.0 meter three-deck screen.

Fine materials separated in the pre-screen

When different types of gravel for concrete and gritting are being produced, primary crushers feed enters first the LT330GPSE pre-screen, which removes the fine materials before going to the cone crusher.

“The pre-screen helps us to only feed pure rock material into the crusher, especially in wet conditions. This makes the production more effective and improves the quality of end products. Metso’s pre-screen works just as we planned,” Jari Pärhä says.

The double-stage plant and mobile screen produce gravel of 6–12 mm and 12–16 mm at an hourly rate of roughly 200 tons. At the same time, the process produces gritting gravel of 3–6 mm and fine rock dust of 0–3 mm. When coarser material is being produced, the capacity increases to 350–400 tons.

Pärhä Oy’s vehicles are used to deliver different types of gravel to companies operating in the concrete industry, for infrastructure construction and to private customers.

“Quality and documentation are important to us. For example, we check the quality of concrete gravel after every 500 tons,” Managing Director Petri Pärhä says.

Asphalt and track ballast as new products

This year, Pärhä will expand its production to asphalt and railway ballast. The company has therefore acquired a quarry from Mäntsälä to produce high-quality aggregates.