Concept: New Zealand-based urban mining company, Mint Innovation (Mint), is developing affordable, scalable processes for salvaging valuable metals from e-waste streams. Mint Innovation’s clean processes leverage biotechnology and hydrometallurgy (biometallurgy), which use microbes to extract value from metal waste streams, thereby minimizing the waste and developing a fully circular economy in precious metals, while mitigating environmental harm.

Nature of Disruption: The Mint process has been optimized to maximize sustainable metal recovery from e-waste while generating minimum waste. E-waste refers to discarded electronic appliances like mobile phones, computers, and televisions. First, any incoming feedstock is ground into fine powder to allow the chemical processes to work efficiently. Once ground, it is then transferred into the first reaction vessel where base metals comprising copper, iron and tin are removed. Proprietary chemical leachate gets added to the solid and stirred, drawing the base metals into the solution. The first leaching process gets completed in about an hour and the solids can be separated from the base metal-rich liquid using filtration. Only precious metals are now left in the solid fraction. The precious metals contained in the leachate like copper can then be removed via electrolysis and other techniques. These extractive metals can then be put back into the economy to make new manufactured goods. The remaining solids are then moved to the second leach to recover the remnant valuable metals which are more difficult to recover than the base metals. This is where Mint’s technology stands apart and its ability to recover precious metals at higher concentrations than other existing methods. Once the metals get dissolved, Mint adds its special microbes into the reactor to absorb the metal ions. This process is known as bio-absorption. The microbes gain weight as they absorb these precious metals, facilitating them to be easily isolated with a centrifuge. Finally, the gold is liberated from the biomass using a gnashing and refining process. The various precious metals can then be extracted using established procedures to produce high-quality metals for use in industry. Metals recycled in this way have a low carbon footprint as well as reducing the environmental degradation associated with mining and other forms of extraction. Also, the process ensures data protection as the remnants get destructed completely.

Outlook: Extensive utilization of electric and electronic equipment in a wide range of applications has resulted in the generation of huge volumes of electronic waste (e-waste) globally. Mint with its innovative processing technology enables product reuse and the recovery of embedded value from waste or end-of-use products. The startup has recently accumulated $20M in funding which it plans to set-up bio-refineries in the UK and Australia with the capacity of processing up to 3,500 tons of e-waste annually.

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