• Share

The ‘circular economy’ in mining and metals

5 October 2017

An idea that’s increasingly gaining traction in academic and thought leadership circles, particularly over the past decade, is that of the ‘circular economy’.

Championed by influential organisations such as the Ellen MacArthur Foundation and the World Economic Forum, the ‘circular economy’ ethos rejects the ephemeral approach of more traditional manufacturing (wherein goods or products are made, used and then disposed of) in favour of a more efficient, environmentally sound and sustainable way of thinking that focuses on the careful management of resources.

In the circular economy, products are designed for high performance and durability (rather than inbuilt obsolescence) and the use of raw materials is optimised – including the intelligent re-use of any waste products created during the manufacturing process.

At the end of a product’s life cycle, the resources used to create it are, where possible, recovered, recycled or re-purposed, creating a responsible, restorative and regenerative cycle that ‘designs out’ unnecessary waste.

How does this apply to mining and metals?

The cyclical approach to manufacturing and resource management is particularly well suited to the mining and metals industry.

On the whole, metals are infinitely recyclable, while their inherent durability, strength and anti-corrosive properties help to enhance the longevity of products in which they’re used. The high value of many metals and minerals also incentivises the recovery of such materials at the end of a product’s life cycle, and hence there are many methods in place to facilitate their re-use and recycling.

The sites of mining operations also have much scope to adopt a circular approach to business. As well as considering the environmental and societal impact of their operations, mining companies can, and do, take steps to minimise negative effects, share best practice and reduce waste.

Re-purposing ‘waste’ products

Mining as an industry creates much in the way of waste – from rock and emissions to water treatment sludge and mine water – and this too can be reused, either within the production chain or re-purposed elsewhere. Waste rock, for example, is often used as backfill, as landscaping material or as aggregate in road construction, while sludge from acid rock drainage treatment – which is high in iron – can be sold commercially for use in pigments. Other by-products of the mining sector can be re-used for making construction materials (such as bricks or cement), resins, glass and glazes, in agroforestry, or as part of the wastewater treatment process.

The smelting and refining stages of the minerals and metals life cycle also have their own waste streams that need to be addressed, via the processing of residues and secondary metals. These are often used alongside primary concentrates, for example, to produce metals with varying amounts of recycled content, while electronic scrap (from the ‘urban mine’ of discarded home appliances, computers, phones et al) can also be re-purposed as part of this process.

The circular approach in practice

Three of ICMM’s member companies based in Japan have taken multiple steps to embed a circular economy approach in various areas of their business and operations:

Mitsubishi Materials has adopted a group-wide recycling-oriented business model, recycling materials and resources across a wide range of fields and throughout its activities, including home appliances, aluminium beverage cans, tungsten and palladium.

Smelting technology is used for the purpose of recycling metals at Mitsubishi’s smelters and refineries, alongside the recycling of scrap for raw materials, thermal energy or recovery of valuable metals. The company also takes in clinker dust as a by-product from its cement plants, and use components like calcium as auxiliary raw materials for smelting. After use, clinker dust turns into copper slag, which is then recycled back into raw materials at the cement plants. Mitsubishi also recycles and recovers rare metals, as well as undertaking ongoing expansion of its pre-processing combustion, sampling, analysing and processing facilities, which are crucial to effective recycling.

JX Nippon Mining & Metals recycles and re-purposes a wide variety of materials, from end-of-life mobile phones to industrial waste oil, via its own environmental services companies. Of the total volume of waste materials the group generated in 2015, 83% was re-used internally, while, in its copper recycling system, around 26% of its total scrap production is recovered.

Sumitomo Metal Mining has similarly taken great leaps in its recycling commitment, with its recovery rates of copper scrap almost doubling in the five years following 2010. High-purity copper scraps are processed directly in its Toyo smelter and refinery, while e-scraps (as found in circuit boards, for instance) containing low-grade precious metals and copper are pre-processed in Sumitomo’s subsidiary company Oguchi Electric, before being delivered to Toyo for processing.