Material Topic: Effluents and Waste

306–1  Total water discharge by quality and destination

Discharges to water derive from dams and tailings ponds at the mines, and from water treatment plants and collection of surface water at smelters and mines. Boliden’s smelters account for approximately 70% of metal discharges to water while the mines account for the remaining 30%. Boliden mines account for 83% of the Group’s nitrogen discharges with the nitrogen generated mainly from the use of explosives and their handling. The remaining 17% comes mainly from wastewater recycling at the Kokkola smelter.

Ensuring efficient and stable operations at water treatment plants and recirculating the process water as much as possible are important parts of reducing discharges to water. Boliden’s operations include purifying process water as well as a significant amount of the rainwater that falls within the industrial areas. In recent years, there has been heavy rainfall, underlining the need for increasing the water treatment capacity, and several of Boliden’s operations have consequently implemented measures to meet this need.

The discharge of metals and nitrogen to water from Boliden's units continues to decrease due to improved water management and control. One example is the nitrogen treatment plants taken into operation during 2017. The management and monitoring of water consumption has also been improved through the decision that all mine units shall have a Water Management Plan. During 2017, five out of six Mine units have implemented a Water Management Plan.

Once the water-cleaning processes are completed, the smelters discharge their water to the sea while the mines discharge the water into rivers and lakes. The water discharged to recipients is monitored to ensure that levels of pollutants are within the quality standards stipulated in the environmental permit. Accredited laboratories, both internal and external, are used for analyses of samples taken on site.

306–2  Waste by type and disposal method

Boliden handles considerable amounts of waste materials. These waste materials mainly comprise various types of dust and slag, tailings, rock, and other mineral formations. Boliden has developed processes to extract as much value as possible out of the material streams at mines and smelters. There are virtually no materials left that can be reused, composted, or incinerated. Boliden chooses, therefore, to report the waste types in a manner that differs from that indicated in the GRI standards. Hazardous waste is sent for disposal or stabilisation, in some cases to landfill and deep repository. The increasing amounts of waste rock in 2017 can be derived from the addition of the Kevitsa mine, a large-scale open pit operation, similar to the Aitik mine.

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

Boliden processes a number of different metals and substances that are both toxic and environmentally harmful. The mining and smelting operations generate residual waste consisting of waste rock, tailings, slag, sludge, and dust. EU waste legislation currently has a strategic approach that views waste as a resource and deposition as the last option (Waste Framework Directive, 2008/98/EC). There is considerable awareness of the importance of waste issues within the Boliden Group: e.g. waste sorting, significant recycling of process residues and scrap, good reporting procedures and ongoing waste projects. The majority of Boliden’s process and mining wastes are sent to landfills in accordance with the EU Landfill of Waste Directive (1999/31/EC) and the Mining Waste Directive (2006/21/EC). The remainder is used as construction material or as filler material. Waste rock dumps are covered continuously, wherever possible, in order to prevent weathering or leaching. Boliden’s mine waste is generally handled in accordance with applicable environmental permits that specify how and where it may be stored and how it shall be covered and reclaimed.

Extensive monitoring programmes are in place to ensure a high level of dam safety and several measures to increase dam safety have been finalised or are in progress. Boliden is responsible for around 40 dam facilities in Sweden, Norway, Finland, Ireland, and Canada. They are used or have been used to deposit tailings sand or other waste and for water management. This figure includes both operational and decommissioned facilities. Dam facilities in Sweden are managed according to GruvRIDAS (mining industry guidelines for dam safety).

Correctly processed waste can be turned into valuable products. What is considered waste for one operation can often constitute a raw material for another. Approximately 45% of the process residues generated are sent to another Boliden site for metals recovery or final deposition. Appropriately handled, the trade in waste and by-products can be of benefit to society by increasing overall resource efficiency. Boliden works continuously to identify internal and external recycling or landfill solutions for any process wastes 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 viewpoint.

The secondary raw materials to Boliden smelters, i.e. electronic scrap and waste batteries, contain plastics that are incinerated in the process. The incineration of the plastics serves as a reducing agent in order to produce the metal. The excess heat from the process is used for district heating.

Volumes are mainly based on loaded weight. Waste rock tonnage is based on calculations of volume and density. Tailings are based on calculations of tonnage of ore minus tonnage of concentrate output.

There are no statistics available for overburden as it is seldom that any overburden exists, and what constitutes a insignificant volume of waste is not defined. Sludge that is not reused in the process accounts for an insignificant percentage of either hazardous waste or non-hazardous waste, depending on its properties.

Some waste is sent for final storage in underground facilities. Tailings are, for example, used as back-fill wherever this is possible, both as reinforcement and to reduce the amount of tailings above ground. Odda stores jarosite and slag in mountain caverns. Rönnskär is in the process of completing underground disposal facilities for arsenic-bearing waste.

Boliden has no organic waste material that is suitable for composting, other than small amounts from canteens, which are sent for municipal treatment.

Boliden does not practise deep well injection or waste ­incineration.

306–3  Significant spills

A total of 23 (28) larger (more than 150 litres) oil and/or diesel spills, were reported from Aitik, Boliden Area, Garpenberg, and Kevitsa. All spills occurred within the mining area. All spills were immediately sanitised and any contaminated soil was excavated.

These events have not entailed any significant environmental impact or caused lasting harm to the surroundings. Investigations have been conducted in conjunction with all of the incidents in order to ascertain the causes of the spills and, wherever possible, to institute measures that will prevent any repeats.

306–4  Transport of hazardous waste

Processing of intermediate and waste products is a natural part of Boliden’s value chain in order to maximise metal recovery levels. However, in some cases hazardous waste is sent for disposal or stabilisation, and/or to external landfill and deep repository. During 2017, 7,400 (5,800) t were sent to external use, treatment, or recovery and 400 (220) t were sent to external disposal.