Boliden Harjavalta has chosen Metso Outotec’s SMD grinding mills to improve the capacity of its slag concentrator, in Finland, the mining OEM says.

Boliden Harjavalta produces high-quality metals for European industrial customers, churning out 120,000 t of copper and 26,000 t of nickel in 2019.

The purpose of the slag concentrator is to recover copper from the slag produced in the copper smelter and to return it to the copper production cycle as high-quality slag concentrate, Metso Outotec said, with grinding being an essential part of the slag concentration process.

The raw materials of the Boliden Harjavalta smelter consist of concentrates and recycled metals, according to Boliden, with the company’s two mines in Finland – Kylylahti and Kevitsa – providing the smelter with concentrates. Concentrates are also purchased from external mines, Boliden says.

The order has been booked in Metso Minerals’ June quarter 2020 orders received.

Based on tests, Metso SMD (stirred media detritor, specialised for fine grinding applications) was chosen as the grinding technology, Metso Outotec said.

“Maintenance for the SMD is safe and cost-effective thanks to the simple mechanical structure of the mill and the smaller number of moving parts compared to traditional grinding mills,” the company explained.

Timo Sarvijärvi, Metso Outotec’s Head of Mining in the Nordics market area, said the company, at testing stage, noticed slag could be processed very efficiently using SMD technology.

“Now the slag concentrator can process larger amounts of material, without compromising the targets set for copper recovery,” Sarvijärvi said.