EnviroLeach Recovers Tin From E-Waste

SEATTLE (ITRI.CO.UK): EnviroLeach is a Vancouver based company that recover gold and other precious metals from e-waste using a water-based solution. This month, the company announced a new technological advancement that allows cost-effective extraction of tin from end-of-life printed circuit board assemblies (PCBAs). E-waste is the fastest growing waste stream in the world, but only 17% is documented as recycled. PCBAs from this e-waste typically contain 2-6% tin, but recovery of tin is challenging and often economically. Cost-effective extraction of tin is therefore essential to adding value to e-waste, reducing tin sent to landfill, and moving towards a more circular economy.

The EnviroLeach process recycles PCBAs in a water-based solution at ambient pressure and temperature producing zero-waste. This process has so far focused on extraction of gold and other precious metals. This month the company announced that they have developed a multi-metal recovery process for tin and copper extraction from PCBAs. First, PCBAs are dismantled in a general dismantling process. The dismantled material is mechanically separated into a copper-rich concentrate and a non-metallic fraction. The metal-rich concentrate could then be sent to a smelter for further refining but, instead, EnviroLeach use hydrometallurgical treatment to dissolve copper and tin into solution at ambient pressure and temperature. Tin is removed from this solution using physical separation methods to produce a marketable tin oxide product. This process allows up to 92.6% of tin from PCBAs can be recovered.

This recovery approach offers both economic and environmental advantages. PCBA mass is reduced by 80% when this copper and tin recovery phase is used alongside EnviroLeach’s existing processing technology. This mass reduction would therefore reduce downstream extraction and refining related charges. Additionally, recovery and sale of tin could increase operating margins. EnviroLeach have so far recycled ten tonnes of PCBAs using water-based ingredients. None of the e-waste components or materials have gone to waste. Their process is therefore zero-waste, and, compared to smelting, has incredibly low environmental impact in terms of pollution and carbon dioxide emissions.

ITRI View: Looking forward, a challenge for EnviroLeach will be finding a suitable and reliable PCBA feedstock for their environmentally conscious technology. Earlier this month, the company made a one-off purchase of 42.5 tonnes of end-of-life PCBs from the Middle East. However, to really make this process scalable, economically viable and green, a reliable, constant, and potentially domestic supply of PCBs is required to keep operating costs and transportation emissions low. If this feedstock challenge is overcome, EnviroLeach’s process could really challenge the PCBA metal recovery market.

Courtesy: www. itri.co.uk