Generally when we think about gold mining, we picture the removal of gold from the ground, either in its pure form or in gold ore. There is another source, however, in which gold is found in relatively high quantities. In fact, the gold content in this material is 40 to 50 times higher than in ore. This mysterious material: electronic waste (or e-waste) — discarded cell phones, tablets, computers, laptops, and other devices. The huge amount of gold and other elements in municipal waste has given rise to the concept of “urban-mining” — the extraction of metals from our garbage.

Gold is an important component of many electronic devices. In 2011 alone, 320 tons of gold were used to make laptops, cellphones, tablets, and other electronics worldwide. This represented 7.7 per cent of the world supply of gold that year with a value of $16 billion. As electronic devices evolve more quickly, their life-cycle is becoming shorter, with people choosing to replace their computers and cell phones more and more frequently. When these devices are discarded, the majority of their gold components are lost, as only 15 per cent of the gold in e-waste is recovered.

Recycling the gold from electronics is appealing for many environmental reasons. Not only is recycling beneficial because it reduces waste and extends the lives of traditional mines, it is also significantly more energy efficient than mining. A huge amount of effort and money is invested in extracting new gold from the ground only for it to be discarded after a single use. Several factors contribute to the low levels of e-waste recycling including economics, low collection rates, and social and government factors. For instance, the cost of the manual labour needed to disassemble the intricate pieces of discarded electronics can be prohibitive, especially in industrial countries like Canada. Furthermore, recycling projects are generally local endeavours, and therefore much smaller in scale then the processing associated with gold extracted through traditional mining.

Gold is only one element that has found use in modern electronic devices. As the number of functions carried out by electronic devices increase, so does their complexity and use of different materials. In fact, many technologies use almost all the stable elements in the periodic table, and the recycling rates for many elements with unique properties are often much lower than those for gold. For instance, the recycling rate of lithium, germanium, gallium, and the lanthanides is less than one per cent.  

The potential for urban mining, therefore, extends far beyond gold. With the amount of e-waste increasing, it may one day become a viable and sustainable alternative to traditional mining.

References
Graedel, T.E., Buchert, M., Reck, B.K. & Sonnemann, G.. (2011). Metal Stocks and Recycling Rates.  Nairobi, Kenya: UNEP.

Reck, B.K., & Graedel, T.E. (2012). Challenges in Metal Recycling. Science. 337 (6095), 690-694.

ScienceDaily. (2012). E-Waste: Annual Gold, Silver 'Deposits' in New High-Tech Goods Worth $21B; Less Than 15% Recovered. Accessed April 2013, from http://www.sciencedaily.com/releases/2012/07/120706164159.htm

UN News Centre. (2012). Links Between Waste Management and Environmental Sustainability Spotlighted at UN-Backed Conference. Accessed April 2013, from http://www.un.org/apps/news/story.asp?NewsID=43426#.UVw3D1eyN8G