Electronic Waste: The Rich Resource in the Urban Mine
Forgetting your mobile phone can be a real pain, playing on your mind during the day. Then as you think you can feel your phone vibrating in your pocket and you come to realise how dependent we are on our gadgets. Electrical equipment has changed our lives completely and we rely on phones, microwaves, TVs, kettles, computers to keep us informed, entertained and even alive. It is hard to imagine what our lives would be like without them. The type of phone or computer someone owns has perhaps replaced jewellery as the status symbol of our time. You can easily imagine the delight someone might have when they turn on their new MacBook in Starbucks, making that Apple logo glow as white as those famous pearls around Audrey Hepburn’s neck and drawing green-eyed glances over coffee cups from across the café. The conveyor belt-like release of new phones, computers and tablets means we are constantly throwing out the old and bringing in the new, even camping outside shops for the privilege. With the rising wealth of many people around the world, especially those in emerging economies, our consumption of electrical goods is continuing to rise and in line with the laws of the conservation of mass, each time we throw away a piece of equipment it adds to the huge amount of waste electronics, which is becoming an ever-increasing problem in our global society.
This growing mountain of e-waste is however becoming a commodity in its own right. Inside this mountain there is a rich source of precious metals. Urban mining is a growing trend in which gold, silver and palladium are recovered from the e-waste, in particular from the printed circuit boards. The concentration of the metals in e-waste can range between 10 to 300 ppm (g/tonne) which is far higher than the primary ore from which the metals are extracted at typically around 4 ppm. In the UK alone around 22 kg per capita of electronic equipment were discarded in 2012 with an estimated total metal value of close to £1bn. We are truly living in a gold mine. However, to borrow the cliché, all that glitters is not gold (or silver, or palladium); there are many hazardous chemicals in e-waste including the heavy metals lead and mercury. Although many hazardous chemicals are now banned from electrical equipment, the long time between getting a new piece of equipment and throwing your old one away (just think of how many phones there are in your cupboard) means that there is a lag time before they enter the recycling loop. The inert nature of the non-metallic components of the e-waste makes extraction of the metals very difficult but this hasn’t stopped a large number of poorly equipped prospectors, mainly from emerging economies, trying to extract the metals by often using highly concentrated acids or openly burning the material subjecting themselves to toxic gases. This practice is banned and heavily condemned, but due to the lack of crackdowns on the shipments of e-waste (often under the guise of second hand equipment) it is rarely stopped.
There are a number of industrial solutions which can be implemented to recover the metals from the e-waste employing either hydro-metallurgical or pyro-metallurgical techniques, or indeed a mixture of both. Tetronics International’s DC plasma technology uses thermal plasma to separate the desired metallic components from the unwanted organic or ceramic fractions in the e-waste. In a single step process, raw shredded e-waste is treated to produce a precious metal rich metallic bullion which can be sent for final refining. The hazardous fractions of the e-waste are either immobilised inside an inert glassy material ‘Plasmarok®’ or captured in the exhaust gas cleaning system.
Not only is the recovery of the precious metals from the e-waste attractive because of their high value, it also helps to diminish the reliance on primary sourced metals which have significant supply risks associated with them. Palladium, an essential component in some electronics, is classified as a critical raw material by the EU because these metals are mined in just a handful of countries, thereby creating an inflexible supply chain; South Africa and Russia provide 78% of the world’s palladium. Mining is becoming increasingly expensive in South Africa due to deeper mine shafts and higher energy costs, whilst in Russia the palladium output is also dependent on the prices of the base metals nickel and copper from which palladium is extracted as a by-product. Diplomatic tensions also can have an effect on the market such as in the very recent example of the crisis in the Ukraine, which caused the palladium price to increase. The trouble is when so much of the supply of such important materials is controlled by one or two countries, consumers are stuck between a rock and a hard place.
Owing to the high availability of e-waste in Europe and North America, there is an opportunity for these areas to become more self-sufficient in raw materials and critical metals. The idea of a circular economy is not new, but it is very applicable to the western markets in the electronics industry or the automotive industry, where the materials we discard can be recovered and reused for the production of new products. Downcycling, i.e. where the quality of the material is reduced over time, can be a problem with the recycling of some metals where the quality of the material is reduced over time, but this not an issue with the key valuable metals in e-waste because their noble characteristics mean they can be recycled infinitely, which makes e-waste an especially valuable resource. Reducing our dependence on mining has its environmental benefits as well due to the huge energy costs in the extraction, milling and separation costs as well as the enormous areas of land required for discarded materials from mines. Furthermore, Tetronics International’s DC plasma furnaces are very compact and require much smaller supplies of input waste to run economically than large smelting operations.
The exploitation of e-waste as a secondary raw material with processes such as Tetronics’ DC plasma smelting will help to ensure a more secure supply of metals for the production of the latest electronics, whilst keeping up the sales of coats, flasks and sleeping bags high for those long nights queueing for the latest phone!