Recycling: minerals engineering's greatest challenge

Whether it be plastics or metals, recycling is very much in the news these days. And so it should be, as it is a crucial area of the move towards a circular economy, where nothing is wasted (although thermodynamics teaches us that this is impossible), and at the end of the life of a commodity, the constituent components are recycled back into the closed loop.

Minerals engineering will play a leading role in attempting to make the throw away society, the linear economy, obsolete and our Sustainable Minerals '18 conference in Namibia in June will focus on the efforts that mineral processors and extractive metallurgists are making to reduce wastes, reprocess existing wastes, and the greatest challenge of them all, recycling.

Recycling is viewed by many as the panacea of sustainability. Once an article has reached the end of its useful life, you take it to a municipal waste centre, and it is recycled for further use. This is fine for products made from a single material such as glass, which can be melted down and reused, or for certain metals which are used in their native form, such as copper. Although the demand for copper is such that over 20 million tonnes of the metal is produced each year from primary orebodies, around 50% of the copper that is used in Europe is recycled and the energy required to recycle copper is roughly 85% less than from primary production.

However when metals are alloyed with other metals or non-metals, recycling becomes much more challenging due to complex functional material linkages.   A United  Nations Environment Program (UNEP) report on metal recycling includes a great analogy: imagine making your morning coffee. With the right tools, it’s easy to combine the water, coffee, milk and sugar to create your drink (similar to a linear economy). But if you had to separate it again into the original four ingredients (as required by a circular economy), that would be rather challenging.

If the metals and other elements are in tiny amounts in a device, then the problem becomes even more complex, and perhaps the greatest recycling challenge is that of recovering metals from waste electrical and electronic equipment (WEEE), (electric) vehicles and other complex high-tech products. Each year the world generates some 50 million tons of electronic waste, ranging from batteries to mobile phones, computers etc, and although such devices may have been discarded, they are not without value—the United Nations recently estimated the total worth of all that e-waste at $55 billion, thanks largely to the trace amounts of gold, silver, and other metals they contain.

Some of these metals, such as germanium and gallium, are dependent on their primary production on base metal mining, from which they are by-products. Indium, now critical to our modern lifestyle, is the most important ingredient, as an indium-tin oxide,  in the production of ubiquitous touch screens. Indium is produced in small amounts from the mining of Zn ores, and the sheer number of smart phones, tablets etc. produced each year requires around 700 tonnes per year of indium. Recent estimates however, suggest that total reserves are around 16,000 tonnes, so it is a very finite resource, and great efforts are being made to recycle it and other "Hi-Tech Metals", as will be discussed by Prof. Jens Gutzmer at Hi-Tech Metals '18 in Cape Town in November.

It is unfortunate that the working philosophy of most mobile phone manufacturers is planned obsolescence,  the average smartphone life cycle in Britain now being under two years and the number of mobile phone users in the world is expected to pass the five billion mark by 2019. A smart phone contains around half the elements of the periodic table, so global efforts are needed to improve the design of components in electrical and electronic equipment to facilitate reuse and recycling and the better recovery of precious metals.

One mobile phone manufacturer which is taking a lead on this is the Dutch company Fairphone, who is taking steps to increase the life of its Fairphone 2, and has enlisted the help of two world experts on recycling, simulation and life-cycle assessment to assess the best way of recycling the phone to recover the maximum amount of contained metals. Dr. Antoinette van Schaik, of MARAS BV, The Netherlands, and Prof. Markus Reuter, the Director of the Helmholtz Institute for Resource Technology, Germany, have worked together for many years on the simulation of recycling systems, including life-cycle assessment and the circular economy (linking product design with physical and metallurgical processing). Markus is MEI's consultant for the Sustainable Minerals conferences, and he was recently awarded the degree of Doctor of Engineering (DEng), honoris causa, by his alma  mater, The University of Stellenbosch, for his outstanding contributions to the science and technology of the production and recycling of metals, as well as to the integration of academic research and practice. His work on recycling, design for recycling, and resource efficiency has contributed towards the creation of processes and tools to develop a sustainable society.

van Schaik and Reuter

Antoinette and Markus used simulation software designed by Sustainable Minerals '18 sponsor Outotec to create models of how all the different elements, alloys, plastics and materials associations in the Fairphone 2 behave in the best recycling technologies available today and which existing techniques could offer the highest recovery rates. Markus will present and discuss their findings at Sustainable Minerals '18. The basis of this work has been published in Minerals Engineering over the years and has now found its path into Outotec’s HSC Sim, considering uniquely the full “mineral” properties of products and scrap to understand how these pass through physical separation and metallurgical processing systems of the Circular Economy.

Recycling and innovative new business models are without doubt society's greatest challenges, and mineral processing and extractive metallurgy will be at the forefront of meeting these challenges, so please do join us in Namibia in June for Sustainable Minerals '18, which runs back to back with Biohydrometallurgy '18, also very much involved with the move towards the circular economy. Then in Cape Town in November, Hi-Tech Metals '18 will present the latest developments in the primary and secondary processing of the metals which are now essential elements of our modern society.

Events not to be missed by progressive modern minerals engineers!

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