Sustainability website / Environment / Air emissions

Policy and approach

Policy and approach / Performance and goals

We reduce harmful emissions to air, water and land and use the highest reasonably practicable level of control from a recognised hierarchy of hazard controls to eliminate or minimise the impacts of our operations including point source, fugitive or accidental harmful emissions, as set out in our Sustainable Development Policy and SD Standard 10. The most significant air emission from Xstrata’s operations is sulphur dioxide (SO₂) from metallurgical sites. Other air emissions include nitrous oxides (NOx), primarily from burning fossil fuels in vehicles and generators, and particulates.

See SD Management Standard 10: Environment, Biodiversity and Landscape Functions.

Performance and goals

Policy and approach / Performance and goals

Overall SO₂ emissions from managed operations increased by 46% compared with 2006 to 368,264 tonnes due to the inclusion of the Falconbridge acquisition.

Mount Isa Mines in north Queensland operates copper and lead smelters which collectively represent the most significant source of SO₂ emissions in the Group. Emissions of SO₂ from Mount Isa Mines decreased by 28,623 tonnes or 12% compared with 2006 to 209,770 tonnes. This performance represents a decrease of 6% and 19% in SO₂ emissions from the copper and lead smelters respectively. In 2007, SO₂ emissions from the copper smelter declined despite higher production rates, due to an improved SO₂ capture rate of 74% following the installation of new converter hoods. This compares to a capture rate of around 65%* on a tonnage basis in 2006. Plans are in place to increase total capture capacity at the copper smelter from 80% to a target of 95% by 2012. Weather conditions during 2007, combined with a planned 20 day maintenance shutdown of the acid plant in November and December resulted in a total of 1,345 forced downtime hours due to the intervention of our Air Quality Control department. This included 1,050 hours at the copper smelter and 294.5 hours at the lead smelter to control SO₂ levels in Mount Isa compared to 654 hours and 200 hours respectively in 2006. Overall the Mount Isa copper and lead smelters have reduced SO₂ emissions by 77% and 33% from the 2000 baseline level respectively.

*Previously reported as 80% capture; 80% represents the total capture capacity at the copper smelter

NOx emissions rose to 1,523 tonnes compared to 1,193 tonnes in 2006, due to the inclusion of Falconbridge operations in the Group total in 2007.

SO₂ capture

Mount Isa Mines established a site-wide Smelter Emissions Project in July 2007 to identify opportunities to increase capture and treatment of sulphur dioxide and heavy metal emissions from the copper and lead smelters with a target of 95% capture for the copper smelter and 98% capture for the zinc-lead operations. The project has already resulted in a 20% increase in capture of blast furnace off-gases through the lead smelter’s flue replacement programme, and copper converter hood replacement and ventilation improvements which have greatly increased capture of gas for treatment in the third-party owned acid plant at the site.

The Smelter Emissions Project team is developing further potential designs through a consultative process with stakeholders and, where feasible, will implement these controls during the next five years. A Panel Assessment Community Perceptions Survey on air emissions was completed in 2007 including interviews with 500 Mount Isa residents.

Work is under way at Xstrata Copper’s Altonorte smelter in Chile to complete a $89 million expansion that includes initiatives to increase sulphur dioxide emission capture to 95% in 2009. Xstrata Nickel’s Sudbury Smelter is implementing initiatives to attain its target of reducing SO₂ emissions to less than 25,000 tonnes per annum by 2015, representing a decrease of almost 40% compared to 2006 levels. The Horne smelter is targeting a capture rate of 95% or above in 2008.