What is Urban Mining?

by Robin Fontaine

Introduction

Our insatiable appetite for more materials is creating gigantic piles of waste waiting to be treated and slowly polluting the surrounding environment [1]. Luckily for us, in front of this ever-increasing mountain of waste arose a new trend called Urban Mining. In simple terms, Urban Mining is the process of recovering and reusing a city’s materials [2]. The concept started to attract attention through the recovery of precious materials from e-waste, such as old computers, TVs and phones, its horizons were quickly broadened to include buildings, infrastructure, cars, metal and anything you can find in a city [3]! 

In its intentions, Urban Mining is close to the concept of circular economy: recycling, recovering or reusing instead of simply throwing away [4]. 

Why is it important?

Today’s cities are essentially mines full of all types of waste but in particular electrical and electronic equipment composed of precious metals and rare earth materials [5]. Currently, most of our e-waste is deported to far-away lands or waiting in quite literal waste mountains [6]. Achim Steiner, Executive Director of the UN Environment Programme (UNEP), even spoke of a “tsunami of e-waste rolling out over the world” [7]! 

This is where Urban Mining is essential; instead of keeping our waste in landfills, or worse, exporting them to developing countries, we have an opportunity to recuperate precious materials. Landfills full of old rusting cars suddenly become quasi-bottomless pits of steel and electronics. Outdated computers struggling to run Windows Vista, first-generation iPhones with battery problems or even large old TVs are transformed into gold mines (hence Urban Mining) [8].

The metal deposits recuperated on e-waste are more than 40 times richer than the ores collected in mines, meaning that companies can obtain 30 times as much gold from a similar amount of waste than ores [9]. If that argument isn’t enough to convince you, Urban Mining is also more environmentally friendly than traditional mining for the same materials. The extraction of raw materials from 100,000 mobile phones produces 316 tonnes of CO2? and 12,750 tonnes less toxic waste than the production of these materials by traditional mining [10]. It also uses drastically less water and does not pollute nearby rivers or cut down neighbouring forests. 

How does it work for e-waste?

The New Zealand startup Mint Innovation uses a clever mix of microbes and chemicals to recover precious metals [11]. The process is relatively straightforward: all e-waste is grounded until it becomes a cloud of fine dust (at which point it becomes complicated to recuperate your photos, so make sure to save them somewhere before, like on a green cloud). The dust is then plunged into chemicals that will dissolve the desired metals, and the waste materials are then filtered out. We now have a liquid containing all the precious metal – isn’t that neat? 

Microbes are then added to the solution containing the chemicals and the dissolved gold. They are specifically designed to attract gold atoms and separate them from the rest of the metals. This technique is called selective biosorption. Microbes are then recuperated, ashed, and we get the recycled gold [12]!

However, while the gold and some other precious metals are recuperated, most of the e-waste will end up… wasted! 

Pitfalls

While Urban Mining provides a great alternative to waste, it is no panacea. The costs of treating the materials often outweigh the cost of buying new, and thus it does not attract big corporations nor does it provide great incentives for policymakers [13]. Even when prices fluctuate and the new is more expensive, the security and the steadiness of the stream is often enough to keep it going instead of turning toward alternative sources of production.

Conclusion

Urban Mining most probably has a bright future ahead. More than 80% of rare earth material presently comes from China, and Urban Mining is one of these solutions that could offer a way to get a steady stream of such material by reversing the supply chain and alleviating the price volatility [15]. With sufficient funding for research and development, the whole process could become less costly, greener and thus more democratised [16]!

If you are interested in this topic, here are a few interesting reads used to write this article!

References:

[1] The Challenges Facing Electronic Recycling, Electronic Recycling Association, URL: https://www.electronicrecyclingassociation.ca/the-challenges-facing-electronic-recycling/ [last accessed on 14/07/2021]
[2] Cossu, R. and Williams, I., 2015. Urban Mining: Concepts, terminology, challenges. Waste Management, [online] 45, pp.1-3. Available at: https://www.urbanmining.it/public/documents/simposio/editorial-waste-management-2015.pdf [Accessed 15 July 2021].
[3] Arora, M., Raspall, F., Fearnley, L. and Silva, A., 2021. Urban Mining in buildings for a circular economy: Planning, process and feasibility prospects. Resources, Conservation and Recycling, 174, p.105754.
[4] Circular Economy, World Economic Forum. Available at: https://www.weforum.org/projects/circular-economy [Accessed 14 July 2021].
[5] The world’s e-waste is a huge problem. It’s also a golden opportunity, World Economic Forum. Available at: https://www.weforum.org/agenda/2019/01/how-a-circular-approach-can-turn-e-waste-into-a-golden-opportunity/ [Accessed 14 July 2021].
[6] [7] UN environment chief warns of ‘tsunami’ of e-waste at conference on chemical treaties, United Nations Sustainable Development. https://www.un.org/sustainabledevelopment/blog/2015/05/un-environment-chief-warns-of-tsunami-of-e-waste-at-conference-on-chemical-treaties/
[8] Cossu, R. and Williams, I., 2015. Urban Mining: Concepts, terminology, challenges. Waste Management, [online] 45, pp.1-3. Available at: https://www.urbanmining.it/public/documents/simposio/editorial-waste-management-2015.pdf [Accessed 15 July 2021].
[9] Delhi, NCR likely to generate 50,000 metric tonnes of e-wast, Times of Delhi. Available at: http://timesofindia.indiatimes.com/articleshow/22187238.cms?utm_source=contentofinterest&utm_medium=text&utm_campaign=cppst  [Accessed 15 July 2021].
[10] Urban Mining, qu’est-ce que c’est ?, Proximus. Available at: https://www.proximus.com/fr/news/2020/20200729-blogpost-urban-mining.html [Accessed 16 July 2021]
[11] This company recycles gold from electronic waste, World Economic Forum. Available at: https://www.weforum.org/agenda/2021/04/mint-innovation-gold-electronic-waste/ [Accessed 15 July 2021].
[12] Biorefining previous metals, Mint Innovation. Available at: https://www.mint.bio/ [Accessed 15 July 2021].
[13] Arora, M., Raspall, F., Fearnley, L. and Silva, A., 2021. Urban Mining in buildings for a circular economy: Planning, process and feasibility prospects. Resources, Conservation and Recycling, 174, p.105754.
[14] Biorefining previous metals, Mint Innovation. Available at: https://www.mint.bio/ [Accessed 15 July 2021].
[15]  Nickels, L. (2020). Reclaiming rare earth metals. Metal Powder Report. doi:10.1016/j.mprp.2019.12.003
[16] The world’s e-waste is a huge problem. It’s also a golden opportunity, World Economic Forum. Available at: https://www.weforum.org/agenda/2019/01/how-a-circular-approach-can-turn-e-waste-into-a-golden-opportunity/ [Accessed 14 July 2021]