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Apr 16, 2021

Double-deck screen removed a bottleneck in the crushing chain

A gigantic dust cloud rises over the rocky Oksala area in Palokka, Jyväskylä. It is -25 °C, and the crushing chain of RKJ Rahikainen Ky is crushing stone as usual. Actually, it is crushing better than before, now that the old screen is no longer the bottleneck in the production process.
Aggregates product at RKJ Rahikainen site

Jukka Rahikainen, one of the owners of the company, steps down from the excavator cabin and comes to talk to us. 

From Petäjävesi to entire Central Finland

“This is a family business. I’ve been involved in crushing with my brother and father since 2007.” Before that, father Reijo had worked in earth construction, digging ditches in forests, for example. 

“They opened a rocky area near our home in Petäjävesi, and we thought that we could start processing it further. Our operations have expanded a bit since then,” says Jukka grinning.

Considering the current situation, it can be said that they have indeed expanded their operations quite a bit. The company already has two crushing chains, one in Palokka and the other one in Leustu, Korpilahti. The goal is to produce one million metric tons per year with the two chains. They are currently producing up to 700,000 metric tons per year. The new Nordtrack™ S2.11 double-deck screen purchased for the Palokka quarry contributes to achieving this goal.

“We were looking for a screen that would had enough capacity to screen the material so that we wouldn’t have to slow down the crushing process. Metso contacted us and asked us if we were interested in trying this kind of solution,” Jukka reminisces.

Metso Outotec equipment at work in RKJ Rahikainen site
End products are piled on different sides of the screen, keeping different grades separated.

New screen helps increase production capacity

The new screen has been in use for six months now. The upper deck of the screen has a 10-mm mesh, and a 2.5-mm mesh is used on the lower deck. When making road-sanding gravel with the previous screen, the capacity was 200 metric tons per hour. Now, it is easy to produce 250 metric tons of clean output if the material is dry. 

All kinds of grades are produced at the Perälä quarry: road-sanding gravel, capillary break gravel and aggregates from 0–16 mm to up to 0–90 mm. According to Jukka, it is possible to produce 300–400 metric tons of 0–31-mm aggregates per hour. When making larger aggregates, only the feed bank and the feeder might slow down the process. 

Dust around the crushing equipment at RKJ Rahikainen site
Frost and dry weather make crushing and screening produce plenty of dust. Equipment has been designed accordingly.

Here at the Palokka site, Rahikainen is using a chain with Metso Outotec’s LT130E jaw crusher and a tertiary crusher, which is their own creation: a MX4 cone crusher installed on a LT300 track. A Nordtrack™ S2.11 screen was added to the chain at the same time with the jaw. It keeps the MX4 cone as full as possible, which enables the crushed stones to have the best possible shape. 

“The shape is important when producing 8–16-mm grades for the construction business. Stones should look like a Rubik’s cube: if there are too many long edges, the stone falls into pieces easily,“ Jukka explains.

Pure power and ease of maintenance ensure good profit

“It has worked well. I don’t know if we really had a bottleneck, but the machine has certainly enhanced our operation. We’ve been able to increase the capacity considerably. Simplicity and pure power. They are the key,” says Jukka.

Jukka also praises the ease of maintenance of the screen. Greasing points have been centralized well and there’s more room around the oil check point, so things have developed a lot. It is easy to change meshes and prepare the machine for transportation. 

“When you fold the conveyors, the screen becomes so compact that there’s no need to have an extra car driving in front when transporting the machine,” says Jukka. 

Metso Outotec's NordTrackTM S2.11 at RKJ Rahikainen site
NordTrackTM S2.11 is a perfect addition to the two-stage crushing chain of RKJ Rahikainen.

Metso Outotec’s maintenance service is also much appreciated. 

“The whole package is really comprehensive, quick and of high quality. We’ve always got help when we’ve needed it, although we haven’t always called them during business hours,” Jukka laughs.

 

Jukka Rahikainen at RKJ Rahikainen site
Jukka Rahikainen is happy with the increase in the production capacity enabled by the new screen.
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