Boliden Odda: A 40-year partnership for sustainable zinc smelting

Boliden Odda demonstrates how sustainable zinc smelting can be achieved at industrial scale. For over 40 years, Endress+Hauser has supported the site with measurement technology and process transparency. Through renewable hydropower, underground residue disposal, recovery of valuable metals from waste streams and data-driven process optimization, Boliden Odda has built one of the world's most climate-effective zinc smelters. The result is a reduced environmental footprint, improved resource efficiency and a planned capacity increase from 200 to 350 kilotonnes of zinc per year.

A key milestone in Boliden’s sustainability journey dates back to 1986. At that time, the plant introduced a new approach to residue management. Instead of disposing of hazardous materials on the surface, residues are pumped into deep caverns in the surrounding mountains, where they are safely isolated. Compared to conventional surface disposal, this solution significantly reduces long-term environmental risks.

Turning waste into valuable resources

Building on this foundation, Boliden Odda later invested in processes that transform former waste streams into valuable products. By using chemical treatment and heating, residues are processed into around 40,000 tonnes per year of so-called Odda leach product. Valuable metals such as silver and lead are selectively recovered. What was previously considered waste is now part of a more circular value chain.

Reliable measurement data and long-term process transparency play a key role in controlling precipitation steps and ensuring stable separation of silver chloride and lead chloride.

Energy efficiency powered by renewable hydropower

Zinc smelting generates large amounts of excess heat, which is systematically recovered and reused within the plant.

The site is supplied exclusively with renewable electricity from hydropower generated by nearby waterfalls. The power plant is located roughly one kilometer away on the fjord. This combination contributes to a very low CO₂ footprint for zinc production of this scale.

Sustainable performance across the value chain

From raw materials arriving by ship to refined zinc leaving the plant, Boliden Odda demonstrates how green energy, advanced process design and reliable instrumentation can be combined into a state-of-the-art zinc value chain. The result is an electrolytic zinc plant with one of the lowest carbon footprints in its class.

Reliable measurement technology and continuous process transparency support these sustainability and efficiency initiatives across the entire value chain.

At the Odda site, Boliden operates its zinc smelting operations under increasing regulatory and societal pressure. Authorities and governments require the metals industry to significantly reduce environmental impact, manage hazardous waste more responsibly and build long-term strategies for sustainable operation rather than short-term compliance measures.

Historically, zinc smelting generated residues containing mercury and other toxic substances. Many zinc plants worldwide still store such materials on the surface in large tailing areas, creating long-term environmental risks and land-use challenges. In parallel, zinc production is highly energy intensive. Balancing high production volumes with low emissions and responsible resource use is a major challenge, particularly for large electrolytic zinc plants.

In response to these challenges, Boliden embarked on a long-term transformation of its operations in Odda. The ambition was to rethink the entire value chain, from raw material intake to refined zinc products, with a clear focus on reducing environmental impact, improving energy efficiency and turning waste into valuable resources.

Flow, pressure and analytical measurements deliver reliable information across the entire plant. Digital communication via HART ensures seamless integration into Boliden’s central systems, supporting commissioning, stable operation, and continuous improvement. Boliden uses this data to optimize processes in a technically and environmentally sustainable way.