Air quality and emissions

Air emissions are produced from mining and metal production. At Xstrata, we monitor and manage sulphur dioxide (SO2), oxides of nitrogen (NOx), carbon dioxide (CO2), lead, zinc, arsenic and cadmium emissions from our metal production facilities, and methane, CO2 and dust from our mining operations. Greenhouse gas emissions are included in the Climate Change and Greenhouse Gas Abatement section of this chapter.

Sulphur dioxide

Xstrata's primary air emission is sulphur dioxide (SO2) from our metallurgical operations. The smelting and refining of sulphide containing ores such as copper, lead, silver and zinc ores, emit sulphur dioxide to air. The majority (94%) of Xstrata's sulphur dioxide emissions are from the Mount Isa complex (copper, zinc and lead operations). The remainder is from Xstrata Alloy's operations.

Overall Xstrata's SO2 emissions increased by 9,272 tonnes or 4% compared with 2004 to 238,564 tonnes. SO2 emissions at Mount Isa copper-zinc-lead complex increased by 5,563 tonnes or 2.5% compared with 2004 to 224,608 tonnes. This performance comprises a 9% decrease in SO2 emissions from the copper smelter and a 15% increase in SO2 emissions from the lead smelter. Emissions levels are broadly in line with production levels, which fell by 7% at the copper smelter and increased at the lead smelter by around 14% year-on-year.

Overall the copper smelter has achieved a 425,543 tonne per annum (80%) decrease in emissions over the 2000 baseline level, following the installation of a third-party managed fertiliser plant, which captures SO2 from the copper smelter to produce fertilisers. Xstrata Copper is targeting an increase from 80% to 95% capture of SO2 emissions from the Mount Isa copper smelter against the 2000 baseline level. Commencing in 2006, the programme includes installing copper smelter converter hoods to capture fugitive emissions, using software to identify air entry points into the copper smelter, resulting in greater process control, improved acid plant efficiency and improving co-ordination between copper smelter and acid plant operations – a key determinant in production and emissions levels from the copper smelter.

The lead smelter at Mount Isa has achieved a 13,447 tonne per annum (10%) decrease in SO2 emissions since 2000. The Mount Isa lead smelter has implemented a series of actions since 2000 including improved gas filtering systems, a new centralised control room and a 270 metre stack to improve the diffusion of emissions. Furnace water jackets have been upgraded to avoid steam generation that would result in increased off-gas volumes and workforce training programmes have been improved to ensure all employees and contractors are regularly trained in optimal working practices to minimise emissions.In 2006, a feasibility study is being undertaken to implement Xstrata's ISASMELT technology (see below) at the zinc-lead smelter at Mount Isa, to achieve further reductions in emissions. The capture system is also being revised to identify improvements in the gas exhaust systems, to enable improved emissions performance as production from the smelter increases.

Xstrata's ISASMELT technology is a high intensity yet simple, low-cost, submerged lance smelting process that can be used for a range of applications including primary and secondary copper and lead smelting, copper converting and copper/nickel smelting. It generates much of its own heat internally thereby reducing the need for external energy. It can also be retrofitted to enable old smelters to capture SO2. In 2006, Southern Peru Copper Corporation is commissioning a new ISASMELT furnace at its Ilo smelter in southern Peru. ISASMELT will enable the Ilo operation to increase SO2 capture from 30% to about 95%. New smelters in China and India are also using ISASMELT technology in their plants and a smelter in Zambia will also start operations this year.

Oxides of nitrogen

Xstrata's operations emit oxides of nitrogen (nitric oxide and nitrogen dioxide) primarily from our mobile equipment fleet. Diesel is the primary fuel and oxides of nitrogen (NOx) are by-products of burning fossil fuels in internal combustion engines and are emitted from the vehicle's exhaust. Xstrata consumed 13.9 million tonnes of diesel in its operations in 2005, an increase of 1.6 million tonnes (12.7%) compared with 2004. Stack emissions of oxides of nitrogen decreased from 1,477 tonnes in 2004 to 1,112 tonnes in 2005, in line with lower production at Xstrata Alloys.

Dust

Mining operations, in particular open cut coal mines, can have an impact on air quality in the vicinity of the operation, predominantly through the generation of airborne dust. Dust can be generated from the movement of material, blasting and vehicle movements or as wind-blown dust from disturbed surfaces and stockpiles. Xstrata uses effective mine planning to reduce the area disturbed by mining and to enable prompt rehabilitation of disturbed areas. We also water unsealed roads for dust suppression.

Other specific controls that may be applied, depending on the nature of the operation and surrounding locality, include restriction of blasting under certain weather conditions, speed limits on unsealed surfaces, water sprays on conveyor transfers and stockpiles, and covered conveyors.

Dust in the workplace also represents a health risk for employees and further initiatives to manage this risk are described in the Health chapter.

Xstrata Ernest Henry Mine: Environmental Officer Reece Wilkie with a dust sampler