Waste

Mineral waste

An estimated 1,956 million tonnes of mineral waste (predominantly waste rock and tailings) were disposed or stored in 2008. This represents an increase of 3.7 per cent from 2007 when we produced 1,886 million tonnes. About 65 per cent of our mineral waste was used as in pit or underground backfill. This backfilling is an important use for the waste because it ultimately allows the open pits to be reclaimed and re-vegetated.

Thirteen per cent of the mineral waste that we disposed or stored in 2008 is considered to be geochemically reactive. Approximately 32 per cent of the land surface used for reactive mineral waste disposal has been covered or capped. This helps preserve water quality and allows vegetation to be re-established.

Since 2004, 23 operations have been visited by the ARD risk review programme which assesses each operation's ARD hazards and management strategies. All existing mines and advanced projects where ARD could pose a significant risk have been visited by the programme.

All managed operations visited by the ARD risk review and mineral waste optimisation programmes since 2004 were in compliance with the relevant government regulations and permit conditions.

Six monthly reporting by these operations indicates that significant progress is being made to address the issues raised by the site visits. Given the long term strategic nature of many of the ARD issues identified, and the long lead times to design and implement some of the studies and corrective actions, we anticipate that this work will continue for many years.

Non mineral waste

There was a significant increase in non mineral waste in 2008 compared to 2007. The majority of this increase is due to the addition of Rio Tinto Alcan operations. Specific hazardous non mineral wastes from aluminium smelters (spent cell lining and kiln grade spar) continue to be accumulated on site.

We disposed or stored 306,000 tonnes of non mineral waste in 2008. This was 126 per cent more than in 2007, when we produced 136,000 tonnes to disposal or storage. Aluminium smelters are significant contributors to our non mineral waste generation. These operations generate specialist wastes produced through the smelting process, including spent cell lining, bath, carbon fines and refractory bricks. In addition, our largest copper producer disposes of significant quantities of non mineral wastes to landfill and other disposal locations. Aluminium smelters together contribute 42 per cent (128,000 tonnes) of Rio Tinto's non mineral waste that was disposed or stored in 2008. 

We found off site opportunities for reuse or recycle of 333,000 tonnes of non-mineral waste including 94,000 tonnes of bulk processing materials from aluminium smelters. 

Forty one per cent of all non mineral waste disposed of was dealt with on site in 2008 compared to 70 per cent 2007.

Of the non mineral waste disposed or stored off site in 2008, 81 per cent was placed in landfills, a decrease from 2007 when 89 per cent was placed in landfills.

Our operations disposed or stored 40,500 tonnes of hazardous non mineral waste in 2007. This increased 169 per cent to 109,050 tonnes in 2008. This was mainly driven by our increased aluminium business.

Eighty six per cent of the hazardous non mineral waste disposed or stored in 2008, and 69 per cent in 2007, was from aluminium smelters. There has been a 15 per cent decrease in the disposal and storage of hazardous waste per tonne of product at aluminium smelters from 2007.

At the end of 2008, 26 per cent of hazardous waste generated during the year was placed in storage pending final disposal or recycle/re-use compared to 53 per cent in 2007.  A total of 51,700 tonnes of hazardous waste was reused or recycled off site, representing 16 per cent of non-mineral waste recycled in 2008.

With an increased exposure to smelting and other downstream packaging activities, the inclusion of Alcan has had a significant impact on our non mineral waste profile.