Sampling gases at their outlet during an experiment on resuspending PCB-contaminated sediments (2010). © BRGM - Philippe Bataillard

Mine waste and urban mining: innovative solutions to reduce primary materials consumption

02.05.2019
From metals recovery from mine spoil to recycling electronic waste, what innovative technological solutions are driving the circular economy forward? Answers from the BRGM with three projects: Ceres, Chromic and Extrade.

A deposit of electronic and electrical waste. © BRGM

A deposit of electronic and electrical waste. © BRGM

As economic growth consumes ever more resources, it is becoming vital to preserve access to certain primary resources that contain strategic metals and other critical substances for the manufacture of electronic and digital equipment. We need to reduce both pressures on supplies and negative impacts from initial extraction through to end-of-life disposal, and more generally to optimise what is known as the “materials cycle”. In other words, we need more reliable supplies of critical metals and materials, while also reducing the impacts of our lifestyles on the environment.

For these purposes, some waste materials can themselves be used as resources and must no longer be simply considered as “waste”.

This is one illustration of the circular economy, which replaces the linear model – where materials move from extraction to manufacture, then to consumption and final disposal as waste – with a circular model where products are considered in terms of flows of materials and energy and reinjected into successive cycles. France and Europe have firmly adopted an approach to promote and establish an increasingly circular economy.

17.5 Mt annual iron and steel production in France, including 51% recycled metals

Innovative technological solutions integrated into existing processes

Recovering the metals and materials contained in waste generated throughout the materials cycle, from mining and primary processing spoil through to urban mine waste (such as waste electrical and electronic equipment, or WEEE) is thus a major challenge.

The BRGM has been developing innovative solutions for these different types of waste for many years, all aiming to generate value from what are in effect new resources. As our scientists explain, “our main goal is to work towards selective recovery of metals and materials under conditions which have themselves been economically and environmentally optimised”.

The processes developed by these researchers actually have several goals: to reduce energy consumption, optimise the recovery of metals and materials, introduce more environmentally compatible and necessarily flexible solutions and promote industrial synergies. These solutions all have one point in common: they are technologically innovative and can be integrated into existing value streams and processes.

Selfrag equipment (selective fragmentation by very high voltage discharges) breaks up fibre-reinforced concrete into fragments and separates the metal fibres from the concrete matrix. Once selectively released, the fibres can be reused to produced new reinforced conrete. © BRGM - A. Chaumerat

Selfrag equipment (selective fragmentation by very high voltage dishcarges) breaks up fibre-reinforced concrete into fragments and separates the metal fibres from the concrete matrix. Once selectively released, the fibres can be reused to produced new reinforced concrete. © BRGM - A. Chaumerat

Three flagship projects

Ceres, Chromic and Extrade, conducted by the BRGM, are all working in this direction. These three projects link up the whole value chain, from the use of mine spoil up to the treatment of e-cards at the end of the chain.

Ceres combines the re-use potential of waste from many different sources, from mine spoil to urban waste and including plastics, metals, ceramics and glass. Ceres shows that innovation in this field is not only technological, but also lies in combined approaches drawing on the ecology of industry. For example, its co-processing approach can be used at once to resolve a major environmental problem (acid drainage) and to recycle urban waste (non-conductive surfaces, substrates, components).

SEM photograph of stainless steel slag, from which the BRGM's Chromic project is seeking to extract valuable metals for reuse (e.g. chromium and niobium). © VITO

SEM photograph of stainless steel slag, from which the BRGM's Chromic project is seeking to extract valuable metals for reuse (e.g. chromium and niobium). © VITO

Chromic and Extrade are focusing primarily on mineralogy approaches to prepare materials for recycling, which is often neglected by some players in the sector although it is an essential step in concentrating extractable value from certain waste fractions.

This is being addressed by Extrade, which is developing new value streams to recycle the permanent magnets containing rare earths found in WEEE (hard discs, audio and video speakers and small electrical motors). Chromic Is focusing more specifically on strategic metals such as chromium, niobium, molybdenum and vanadium.

All three projects demonstrate the BRGM’s capacities for innovation to develop the circular economy.

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