Once the bulky boring bits that make up most of the electronic waste stream have been removed, recyclers are left to deal with an incredibly complex mix of metals and other components.
Some of that complexity is found in the lithium batteries that power most of our mobile devices. Battery recycling involves a mix of shredding, physical metal separation and wet chemistry to recover carbon, cobalt and lithium. Then it’s on to the real challenge: the printed circuit boards (PCBs).
PCBs are a treasure trove of gold, silver, copper, aluminium, tin, nickel, zinc and iron. They also contain nasty things like lead and mercury, so there are both economic and environmental reasons as to why recycling is the best form of e-waste management. The economics aren’t confined to the intrinsic value of the metals. Recycling metals saves large amounts of energy compared to making them from virgin materials; up to 95% in the case of aluminium and 85% for copper. Even so, most of the processes used in re-purifying all the metals from the mix found on PCBs involves a lot of heat, and some corrosive chemicals.
Separation Through Distillation
Mercury is recovered by distillation. The principle is basically the same as distilling water or whiskey. Mercury has a much lower boiling point than other metals so it is relatively easy to turn into a vapour. All the other metals are left in solid form. The mercury vapour condenses on a cold surface, resulting in a high-purity product.
Bringing The Heat
Smelting is usually associated with extracting metals from their ores, but is also important in separating mixed metals. It involves two key steps: oxidising the mixed metals, then heating the oxides to the relevant temperature at which each metal converts back into metallic form.
Refining Its Purity
Refining involves further purifying metals. As opposed to the chemical changes that are part of smelting, refining usually sees the metal remaining in the same chemical form as it goes through various processes to increase its purity.
A specialist form of refining, electrowinning produces high purity metals. The impure metal may be dissolved in a water-based solution or in a molten salt, or it may form the anode in the electrolytic cell. When an electrical current is passed through the cell, high purity metal collects on cathode.
E-Waste Transforms Into Treasure
Together, these processes see over 90% of the metals contained in e-waste recovered at a level of purity that allows them to be used again and again. Aside from the energy benefits mentioned above, all this recycling of e-waste reduces the need to mine ores, producing an additional win for the environment.
Unfortunately, much of that potential good is not being realised due to low electronic recycling rates. So before you toss out that out-dated phone, clunky old monitor or dead computer, check out how easy it is to recycle e-waste. It really is the case that your e-trash is someone else’s treasure.
If you’re a household looking to recycle your old phones, computers or TV’s, you can find all your local recycling centres here. For businesses who have large quantities of e-waste, you can give us a call on 1300 32 62 92 or fill out the form below to get started on recycling your e-waste with Australia’s largest mercury recycler.