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When electronic products, such as computers, cell phones, televisions, VCRs, stereos, copiers, fax machines1, internal chips and other relating parts, reach the end of their lifetime, they become electronic waste, otherwise known as “e-waste.” E-waste can often comprise of several hazardous components which can include heavy metals like mercury and lead. Despite this reality, gold, as well as other precious metals, also make up a significant amount of e-waste, and its extraction could have advantageous properties for the gold industry.
E-Waste Statistics2
- It is estimated that 20-50 million metric tons of e-waste is disposed in landfills around the world each year.
- Dumped e-waste is estimated to contain over $60 million in gold and silver every year.
- In the United States alone, e-waste accounts for 2% of all trash that is dumped in landfills. E-waste also accounts for 70% of all overall toxic waste in the United States.
- Approximately 12.5% of e-waste is currently being recycled.
- For every 1 million cell phones that are recycled, the following amounts of precious metals can be recovered:
- 16,000 kg of copper
- 350 kg of silver
- 34 kg of gold
- 15 kg of palladium
Gold Extraction by Cyanide
Since its introduction into the mining industry during the 1870s, the use of cyanide in gold leaching has been a useful, but dangerous technique of metal extraction. This extraction process involves the chemical reaction between the pulverized e-waste and sodium cyanide, which produces a soluble gold cyanide solution that allows for easier extraction of the precious metal3. While useful, gold cyanidation remains a controversial technique that is prohibited in several countries around the world. Several mining extraction procedures throughout history that have employed this technique have resulted in disastrous cyanide spills that have severely effected the environment.
Other Traditional Methods of Gold Extraction from E-Waste
Acid Treatment
The combination of hydrochloric acid and nitric acid have been found to be useful chemicals in the extraction of gold from e-waste. Other mild acids have also been successful in their extraction of gold, as these acids can successfully dissolve gold while limiting their potential to cause adverse effects to the environment.
Bioleaching
Microbiological processes have been proposed over the last decade as possible alternatives to extracting precious metals such as copper, gold, palladium and silver from e-waste. Bacteria such as Thiobacillus ferrooxidans and T. thiooxidans, as well as fungi including Aspergillus niger and Penicillum simplicissimum have been documented to successfully extract copper, aluminum, lead and zinc from e-waste4. Aspergillus niger and Chromobacterium biolaceum are two microorganisms that have been found as suitable and sustainable methods of extracting gold from gold plated electronic devices5.
EnviroLeach’s Eco-Friendly Formula
Vancouver-based EnviroLeach Technologies is a science and technology company that aims towards developing environmentally friendly technologies that specifically cater to the mining industry. EnviroLeach’s patent-pending formula is a water-based extraction technique that will eliminate any potential harm that could be caused to the environment or human health during its operation. The new technique will involve the combination of the pulverized e-waste with the water solution that contains a total of five ingredients6. Once the water solution has pushed through the cells of the e-waste components, electricity is applied to the entire system, effectively separating gold and other precious metals in the process for future use.
Advantages of Gold Extraction from E-Waste
Not only does the extraction of gold from e-waste greatly reduce the amount of waste that is carelessly deposited into landfills around the world, but it also provides a new recycling opportunity in an environment that desperately needs new sustainable options. The innovative project proposed by the joint effort between EnviroLeac and Jabil Inc. will reduce up to 50 million tons of e-waste that is dumped into landfills each year. If such extraction procedures can reduce the amount of gold that is mined around the world each year, Researchers believe a significant reduction in both carbon emissions and other harsh environmental consequences that result from gold mining will also occur. The potential for the recovery of gold and other useful metals from e-waste to benefit both the global economy and society at large is unimaginable.
Image Credit:
Stephen Gibson/ Shutterstock.com
References:
- “What Is E-Waste?” – CalRecycle
- “11 Facts About E-Waste” – DoSomething
- “Treatment of Ores Containing Reactive Iron Sulphides” – Multi Mix Systems
- “Bioleaching of gold, copper and nickel from waste cellular phone PCBs and computer goldfinger motherboards by two Aspergillus nigerstrains” J. Madrigal-Arias, R. Argumedo-Delira, et al. Brazilian Journal of Microbiology. (2015). DOI: 10.1590/S1517-838246320140256.
- “How to Recover Gold from e-Waste” – Pace Butler Corporation
- “This new method for getting gold from e-waste may be just what miners need” – Mining.com
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