To improve sorting efficiency, Sätertorps Grus AB in Sweden first had to address the issue of handling the muddy and sticky material. Metso's Lokotrack® ST3.8™ helps Sätertorps Grus AB to separate mud and clay from stones.
Based in Strängnäs, Sätertorps Grus AB is a small family-owned company that has existed in its current form since 1981. The company produces approximately 300,000 tons of natural gravel and crushed stone per year, which compares very favorably to the market's major players. Nowadays, crushed stone is produced on a larger scale than natural gravel, which is consistent with the government's environmental policy. Sätertorps Grus believes that it is precisely these policies that have been problematic for its competitors that have been working in this area for a longer period of time.
Spread across six hectares, the open-cast mine is a combination of natural-gravel and rock quarry. Sätertorps Grus engages a contractor to manage the actual crushing of stone inside the two hectare, 15-meter-deep pit. At the moment, Sätertorps Grus has plenty of work because of ongoing projects in the local area, like the building of a railway tunnel, a railway station and housing.
"The main customers come from within the concrete industry: 80% of our business is concerned with providing aggregate for this sector, so it is clearly our core business," explains CEO Ola Åkerman. But private individuals can also turn to the company for delivery or collection – as they do, especially during the summer.
Cleaner stones, clear advantages
When it was time to invest in a sorting plant, Åkerman was recommended to turn to Metso. This was a supplier that he was already aware of and one that had a good reputation for quality. Another important factor was the local availability of Metso's services.
"Metso has a service agreement with our mining contractor and has delivered the crushed stone used in the quarry. It was a combination of several favorable factors that led to our decision," explains Ola Åkerman.
Micael Larsson, Sales Engineer within crushing and screening, continues: "Metso's Lokotrack® ST3.8™ mobile screen arrived in August 2015, upgraded with the optional vibrating grizzly. At the edge of the ridge of boulders, the material is sticky and muddy, so it's clearly advantageous to have the grizzly, which removes the mud from the stone material before it continues up into the chute. The result is cleaner stones and more efficient sorting."
According to Larsson, there is a large market in Sweden for this type of sorting plant and he hopes that more businesses will realize the advantage provided by the grizzly in areas where the material can be muddy or covered in clay.
*Metso Outotec was formed July 1, 2020 when Metso and Outotec merged into one company. This case study has been written prior to the merger under the old company name.