Solutions to multiple challenges
The electrochemistry of copper offers promising avenues in the fields of energy transition and sustainable manufacturing.
Energy storage with redox flow batteries
Redox flow batteries (RFBs) are a type of electrochemical energy storage device. This means they store electrical energy in chemical form and subsequently dispense this energy in electrical form via a spontaneous reverse redox reaction of dissolved ions in positive and negative electrolytes. These electrolytes are collected in external tanks and pumped into a power module for charge and discharge. The concept is modular and highly scalable.
Aalto University (Helsinki, Finland), Aurubis (Hamburg, Germany)
Aalto University is developing an RFB based on the electrochemistry of copper. This battery would be more cost-effective and scalable than state-of-the-art vanadium RFBs. The initial feasibility of the concept has been demonstrated, and the basic principles patented in Finland by Aalto University. Laboratory-scale multicell prototype stacks were designed and operated in a nationally funded project in 2016.
In 2020, the concept received funding for its next step under the Horizon 2020 program. Through the CuBER project, a 5kWDC pilot will be designed for its integration in Smart Cities and residential self-consumption market segments. Subsequently, the planning of further developments will allow its application at larger scales, both as back-up power system in isolated areas (i.e. copper mining) and for energy management and grid balancing in renewable power production.
The initial niche market would be in remote microgrids. Printed circuit board (PCB) etching waste could be used as an inexpensive copper source for preparing the electrolytes, one of the RFB’s main components. Thus, industrial waste streams would be converted into flow battery electrolytes, which could in turn be further recycled after battery use.
Facts & figures
Electrochemical efficiency of 70% has been achieved in prototype systems that have been operated for over 1000 hours. Cost projections indicate the possibility of reaching a price of €150/kWh at relatively low production volumes of below 1 GWh/year.
It could be argued that RFB technology will be demonstrating a truly circular economy within the copper and energy storage industries, by converting industrial waste streams into flow battery electrolytes.
Integrated Hydro-Pyrometallurgical Processing for Maximised Recovery of EOL Equipment Metals (HP-Source)
The central idea of HP-Source is the creation of a hydro-pyrometallurgical flowsheet that can be easily integrated into current industrial processes for maximised recovery of metals within secondary raw material end-of-life (EoL) products with emphasis on nickel metal hydride (NiMH), lithium-ion (LiBs), end-of-life vehicles (ELVs) batteries and WEEE.
Aalto University, Department of Chemical and Metallurgical Engineering, Research Group of Hydrometallurgy and Corrosion
European Copper Institute
VB Consulting Oy (Pori, Finland)
Applications & added value
Resulting enhancements to current practice will result in increased sustainability throughout the whole circular economy of metals. Additionally, HP-Source will use novel approaches that are not yet fully developed for metals recycling from batteries or WEEE, to obtain competitive products (e.g. electrode materials for energy storage devices, functional surfaces and new ceramics) from waste. HP-Source incorporates numerous stakeholders throughout the various processing stages of secondary raw materials to develop strategies for the efficient recovery of valuable components from the entire value chain that minimise waste and maximise recovery.
ElectroReco is a project involving new electrometallurgical processes for the recovery of metals (Zn, Cu, Cd, As) and the neutralisation of the ecological impact of dusts, especially flue dusts from copper smelters. One of the main goals is to minimise the generation of waste products during the process of metal extraction from pregnant leaching solutions, by means of the selective potential-controlled electrolysis (PCEl) process and suitable mineral processing of the flue dust. To increase the rate of metal recovery, different leaching techniques will be used, as well as different leaching reagents, and kinetic studies will be performed. Subsequently, an innovative process of PCEl electrodeposition of other metals will be further developed.
Industrial Chemistry Research Institute (Warsaw, Poland)
Electrowinning Technologies Ltd (Bristol, United Kingdom)
Atlantic Copper SLU (Huelva, Spain)
Université de Reims Champagne-Ardenne (Reims, France)
École Polytechnique Fédérale de Lausanne (Lausanne, Switzerland)
Energieonderzoek Centrum Nederland (Petten, the Netherlands)
VP Nanotec SpA (Chile)
EcoMetales Ltd, filial CODELCO (Chile)
Nanometallurgy SA (Wrocław, Poland)
Potential-controlled electrolysis (PCEl) has been tested at laboratory, pilot and industrial scale (in real copper smelter plants) for copper electrowinning and electrorefining processes. A proposal to apply for Horizon 2020 funding was presented in 2017, but was unsuccessful. The project has been submitted as part of another H2020 call in 2018 but has not been retained for funding in this highly competitive field. Potential consortium members are invited to express their interest.
Presently, current-controlled (galvanostatic) copper electrolysis processes are very sensitive to changes in copper electrolysis conditions. With potential-controlled electrolysis, however, a high-purity copper is obtained in all circumstances. The PCEI method is much less sensitive to changes in the composition of the electrolyte, resulting from alterations in the composition of the copper anode, for example. PCEI is therefore a less complex and less expensive technology for metal extraction from, for example, pregnant leaching solutions.
Facts & figures
PCEI not only improves the process rate of copper electrorefining deposition up to two times, but also makes it possible to obtain a product with more that 98% current efficiency. PCEI can be carried out with a mass transport control regime, at very high current densities, giving very good quality products. The main driving force in this case is natural convection, which improves the energy consumption and current efficiency of the process.
The utilisation of industrial residues for the recovery of valuable elements can bring significant economic and environmental benefits. Potential-controlled electrolysis enables electrowinning and electrorefining processes to be carried out in conditions in which traditional methods could not be used, for example at low temperatures and low concentrations of metal, or without organic additives.
Thermally regenerative batteries
Large amounts of low-grade waste heat (temperatures <130°C) are currently released during many industrial, geothermal and solar-based processes. Thermally regenerative batteries (TRBs) can convert this waste heat into electrical power. Thermally regenerative ammonia-based batteries (TRABs) as well as acetonitrile based batteries, based on copper electrodes, have already been developed to produce electrical current from the formation of copper-ammonia or copper-acetonitrile complex, using waste heat to regenerate the process.
University of Palermo (Sicily, Italy)
Penn State University (Pennsylvania, US)
WIP Renewable Energies (Munich, Germany)
École Polytechnique Fédérale de Lausanne (Sion, Switzerland)
The University of Palermo, together with Penn State University and WIP Renewable Energies, carried out a small TRAB project in 2016, supported by ECI. Some further investigations are taking place in 2017 and 2018, as part of the H2020 RED-Heat-to-Power project.
The École Polytechnique Fédérale de Lausanne has been developing copper-acetonitrile based systems in a three-year project supported by the Swiss National Science Foundation (Ambizione Energy, grant 160553), since 2016.
The new TRAB technology can be applied to convert low-grade waste heat, which cannot be used for any other application, into power. The process increases the efficiency of the manufacturing industry, and reduces its carbon emissions.
Facts & figures
It is estimated that in Europe alone, TRAB technology could generate about 6 TWh of electricity per annum. This is comparable to the electricity generated by solar panels in Europe in 2010.
TRAB technology delivers electricity that is generated on-site at the manufacturing plant, so it does not need to go through the transmission and distribution network. When fully dispatchable, TRAB technology is more valuable than variable solar and wind sources.
In-situ copper control
Liberation of copper is a part of the copper electrorefining process that is often overlooked. Liberation is carried out for two purposes – as part of the electrolyte impurity control process and also to control the copper concentration in the tankhouse. With traditional liberation, the B-grade copper produced is usually circulated back to the smelter, wasting the electrical energy used to produce it.
In a patent-pending concept (PCT/GB2017/051248, submitted 4 May 2017), expertise from both power electronics and base-metal tankhouse technology is combined to improve copper concentration control in copper electrorefining.
Electrowinning Technologies Ltd (UK)
EWT Ltd has secured an agreement with a European copper refinery for a six-month demonstration programme, scheduled to commence at their plant in early 2018.
The technology will be retrofittable to any copper electrorefining tankhouse where there is a requirement for copper concentration control in the process flowsheet.
Facts & figures
In Europe, there are around a dozen copper electrorefineries producing a combined 2.5 million tonnes of copper cathodes per annum.
Each in-situ copper control unit should be capable of producing between 2.5 and 3.0 tonnes of Grade-A copper annually. Depending on the concentration of oxygen in the copper anodes, it is estimated that, in Europe, in the order of 10-20 thousand tonnes of A-grade copper could be produced by means of in-situ copper control, representing a potential market for between 4,000 and 8,000 in-situ copper control units in Europe alone.
In addition to replacing the traditional B-grade liberator cathodes with A-grade copper, a number of other benefits are expected, including:
a decrease in the handling of B-grade cathodes,
a decrease in residence time in the process for several thousand tonnes of copper per annum,
free-up of capacity in the smelter as fewer B-grade cathodes are returned,
all the benefits in liberation of moving from lead anodes to catalyst-coated titanium anodes - energy savings and no lead contamination,
process simplification for cast copper anode handling: by eliminating end-of-cell ER anodes, which currently have a residence time twice that of the other copper anodes in the ER cells.