Air & Waste

Waste

Wastes and residues from our operational activities are a key area of environmental risk management for us. We try to minimise our impact through careful waste management, including mineral waste such as waste rock, slag and tailings, and non-mineral waste such as used oil, office and processing waste. We do this across our operations in many ways.

Turning slime into solar panels

Tellurium is one of the rarest elements on Earth. And it’s an increasingly important one, because it’s used in many emerging technologies – like cadmium telluride (CdTe) solar panels, a highly efficient, rapidly manufactured, and lower-cost alternative to conventional silicon-based panels. Tellurium is usually found in small, sparse rock deposits, making it difficult to mine at scale. But at our Kennecott copper operations near Salt Lake City, Utah, we’ve discovered a way to extract tellurium from an unlikely source – slime.

From waste to soap

For example, at our Oyu Tolgoi operations in Mongolia, 40-50% of waste materials are diverted from the waste management centre through re-use and recycling programmes. Not only is this reducing the volume of materials going to the landfill (prolonging the operational life of the waste management centre landfill cells) but it is also supporting Mongolian communities and industries. Waste oil is treated for reuse as lubricants, waste plastic is recycled into plastic pellets for reuse in the manufacturing of other products, and plastic pellets are converted into packaging and medical sharps containers. Used cooking oil from our kitchens is purified by a local company and used to make soap.  

Using waste from aluminium processing to grow blueberries

For more than a decade, we have had a dedicated team – including scientists, and marketing logistics experts – whose job has been to find value from the 350,000 tonnes of non-bauxite residue by-products we produced every year from our aluminium operations in Quebec, Canada. Currently, 85% of this is used to make new products. For example, we have turned anhydrite, a by-product from our Vaudreuil alumina refinery in Canada, into a safe and effective fertiliser for local blueberry growers.

A new way to make cement

We are working with Geocycle Canada and leading construction materials company Lafarge Canada to reuse waste from the aluminium smelting process to make cement. This new product – called Alextra – is made from used potlining, as part of the aluminium electrolysis process that would otherwise go to landfill. Alextra is the result of years of research and development, aimed at finding new ways to deliver sustainable outcomes and value from used potlining. Lafarge Canada will produce on average one million tonnes of cement a year at its facilities in Bath, Ontario, using Alextra as an alternative to raw materials such as alumina and silica, which are commonly refined or mined for use in the manufacturing of cement.

"As a global leader in building materials, we are committed to living up to the responsibility of helping to create a zero-waste future. In order to achieve this goal, we need progressive partners such as Rio Tinto.”

- Travis Smith, Geocycle Canada

It is not always possible to reuse or recycle waste, so we continually develop technology and build facilities to manage it in ways that minimise adverse environmental and community impact, disposal costs and future liabilities.

2016: At our Vaudreuil alumina refinery in the Saguenay, Canada, we implemented a two-phased project to overcome technical, environmental and social challenges and ensure the refinery could continue to operate in the future. Following public consultation, we built a new facility to filter and reduce the volume of bauxite residue waste at the existing storage site.

2017: Our development of a drilling waste removal system was awarded a certificate of merit in Western Australia’s 2017 Golden Gecko Awards for Environmental Excellence. This award recognises leading practice and innovation in environmental management and provides an opportunity to share experiences between government, industry and the community.

2018: Our Iron Ore Mineral Waste Management team won an International Network for Acid Prevention (INAP) Best Practice award: “Pilbara operations exemplify global best practice and deserve international recognition”.

Emissions and air quality

Clean air is critical for the health of our host communities and of the surrounding ecosystems. Our emphasis is on prevention, managing air quality through operational discipline and process improvement.

We comply with local and state regulations to protect air quality, and we also have our own air quality protection standard. This outlines requirements for how to monitor and manage air emissions at our managed operations. It also provides the framework to prevent, or otherwise mitigate effects that our activities could have on host communities and the environment. To do this, we work to understand our emissions and potential impacts, control emissions at their source, and implement strategies to deal with adverse conditions.

Mining processes, such as the use of fossil fuels, moving ores, waste streams, and smelting metals release gases and particulates into the atmosphere. The major air emissions from our operations are:

• Sulphur oxides (SOx), mainly at our aluminium and copper smelters and coal and fuel oil fired power stations
• Nitrogen oxides (NOx) from burning fossil fuels
• Gaseous fluoride emissions from aluminium smelters
• Respirable particulate emissions – very fine particles from mining and processing operations and from burning fossil fuels

We monitor and control air emissions where we operate. Our site-based monitoring includes tracking and reporting air quality parameters at intervals related to the type of emission risk, and the requirements of stakeholders and regulators. We use this data on a continual basis to ensure mitigation and control systems are working as expected and to make adjustments where necessary.

Reducing greenhouse gas (GHG) emissions

In 2021 we announced new Scope 1 and 2 targets: We brought forward our 2030 target of reducing our scope 1 and 2 emissions by five years. We also tripled our 2030 target, increasing it to a 50% reduction in our scope 1 and 2 emissions.