SUSTAINABILITY TOPIC: Extractive waste and slag

306–3  Waste generated

Boliden has developed processes to extract as much value as possible from the material streams at mines and smelters. Some hazardous waste is sent for disposal or stabilization, and in some cases to landfill or deep repository.

Correctly processed waste can be turned into valuable products. Some of the process residues generated are sent to other Boliden sites for metals recovery or final deposition. What is considered waste for one operation can often constitute a raw material for another. When appropriately managed, the trade in waste and by-products can be of benefit to society by increasing overall resource efficiency and circularity. Boliden works continuously to identify internal and external recycling or landfill solutions for any process waste generated. Boliden receives significant amounts of waste from external parties for recycling, construction purposes or safe deposition in landfills.

The export of waste to landfill or for recycling is extensively regulated. Boliden has also developed procedures for monitoring and following up on the receiving party’s processing operations to ensure that their waste processing is acceptable from a health and environmental perspective.

The secondary raw materials for Boliden smelters, such as electronic scrap and waste batteries, contain plastics. The plastics serve as an energy source in metal production. The excess heat from the process is used for district heating.

As there are no significant waste losses in the production processes at Boliden’s units, the waste Boliden generates is considered the same as waste that is either diverted or directed for disposal.

306–4  Waste diverted from disposal

Each unit is responsible to report the waste they consider most significant in their waste streams. The division between the internal and external treatment of waste is followed up internally.

Waste diverted from disposal by treatment method (metric tons)



Non-hazardous waste, total




Used for construction


Other recovery operations



Hazardous waste, total




Other recovery operations


306–5  Waste directed to disposal

Each unit is responsible to report the waste they consider most significant in their waste streams. The division between the internal and external treatment of the waste is followed up internally.

Waste directed to disposal by disposal or
treatment method (metric tons)



Non-hazardous waste, total


Incineration with energy recovery


Storage before final disposal




Other disposal operations


Hazardous waste, total


Incineration with energy recovery


Incineration without energy recovery


Storage before final disposal


Deep-well injection/underground deposit




Other disposal operations


MM3  Waste types and disposal methods including overburden, rock, tailings and sludge, and their associated risks

Mining and smelting operations generate residual waste consisting of waste rock, tailings, slag and sludge. Boliden extracts and processes several different minerals and metals that are potentially both toxic and environmentally harmful. For example, some of the tailings and waste-rock generated are potentially acid generating, which requires adequate management to minimize the generation and release of acid rock drainage. There is considerable awareness of the importance of waste issues within the Boliden Group, and the company conducts selective waste management, waste sorting, recycling of process residues and scrap, reporting procedures and ongoing waste R&D projects. Boliden’s waste streams are managed in accordance with the EU Directive on the Landfill of Waste and the Extractive Waste Directive. Progressive reclamation is applied where suitable, for example waste rock facilities are covered and re-vegetated progressively to minimize weathering and leaching. Boliden’s extractive waste is handled in accordance with applicable environmental permits that specify how and where it may be stored and how it shall be covered and reclaimed.

Boliden follows international guidelines on dam safety and as a member of the ICMM, Boliden implements the GISTM. Boliden is responsible for operative and closed tailings facilities in Sweden, Finland and Ireland. Boliden is also responsible for various dams used for water management.

In underground mining operations, tailings and waste rock are used as backfill, as reinforcement and to optimize the mineral extraction process. About 6% of the tailings and 25% of Boliden’s waste rock were reused in 2021. This decreased the number of tailings and waste rock needed to be deposited above ground. Selective waste rock management makes it possible to use parts of the waste rock by complying with set criteria to allow it to be used as construction materials, both on and off site. Tailings and waste rock used for backfilling are not considered to be waste and are not reported as such.

Waste from extractive industries (metric tons)





Reuse - backfilling of mine


Waste rock








Reuse - construction material 1)


Waste rock








Waste rock (landfill dumps)




Sold waste rock




Tailings management ­facility


52,843,000 2)


1) Numbers for construction and backfilling were separated in 2021.

2) Corrected calculations.

At open pit mines, Boliden selectively manages overburden and topsoil, which are stored separately and used in the reclamation of the different sites.

In early 2021, the construction of a new leaching plant at the Rönnskär smelter was completed. The plant enables waste materials that have been stored at the site since 1975 to be reprocessed. This will eventually reduce the 460,000 metric tons of waste materials currently stored to 220,000 metric tons. The remaining waste will be stored in an underground repository, located under the Rönnskär smelter plant. The deposition of waste material in the repository commenced in 2021. This is a globally unique solution and is the only place in the world where a deep underground repository has been constructed at a smelter site.

Boliden’s operations generate 1.2 million tons of hazardous and non-hazardous waste, which is sorted at the respective sites and collected by authorized waste management companies for further processing or final deposition according to the applicable legislation. Smaller amounts of everyday waste, such as waste generated from canteens, are sent for municipal treatment.

Safe and responsible tailings management

The International Council on Mining and Metals (ICMM), the United Nations Environment Program (UNEP) and the Principles for Responsible Investment (PRI) conducted a review and launched a global industry standard on tailings management in August 2020.

Boliden’s position regarding the implementation of the Global Industry Standard on Tailings Management (GISTM) is that all Boliden’s facilities with “Extreme” or “Very high” potential consequences will conform with the Global Industry standard on Tailings Management within three years from August 5, 2020, and all other facilities within five years. Two of Boliden’s Mines are rated as facilities with very high consequences. A high-level structure for the implementation of the GITSM and starting up the site-specific implementation was ongoing in 2021. During 2021, large investment projects related to tailings management also commenced and continued – both to enhance Boliden’s operations and minimize risk. For example, Boliden’s mine sites have increased their tailings storage capacity with planned dam uplifts and risk assessments have been performed in accordance with current standards to minimize risks.

More information is available in the Annual and Sustainability Report on page 19.