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BUSINESS BLOG – Metal Recovery From Incinerator Bottom Ash

Fraser Valley (Catherine Hercus) – Did you know that precious metals can be extracted from the left-over ash from incinerators?

Fraser Valley company Sepro Mineral Systems Corp. recovers rare elements and precious metals in a type of mining called urban mining. What is urban mining? Urban mining is the process of recovering compounds and elements from used products, buildings, or e-waste. This is an ecofriendly process as the elements are reused instead of being mined from the earth.

What is e-waste? This refers to discarded electronics including cell phones, DVD players and computers. In 2020 53.6 million tonnes of e-waste was produced, but only 12.5% of this was recycled!

One of the waste products which Sepro processes is called incinerator bottom ash (IBA). This ash is produced from waste to energy and incineration facilities. The ash is the material which is left over after incineration which does not fully burn. Did you know that this bottom ash often contains heavy and precious metals including aluminum, copper, stainless steel, zinc and ferrous? Using Sepro’s Falcon Centrifugal Concentrators, these metals can be recovered and sold to metal refiners and recyclers. These machines can recover metals with fine particle sizes from 0-2mm. Particles this small were previously unrecoverable.

Where does IBA come from? Precious metals are found in fine IBA originating from jewelry and electronics. Fine IBA contains gold, silver and platinum. An iron product is produced using a low intensity magnetic separator, and a precious metal concentrate is produced by Falcon centrifugal concentrators. These plant processes minimize heavy metal and leachable contaminants in the leftover ash which is sent to landfills.

Bottom ash is fed into a wet jig or screen, which separates the fines. In the first step, a low intensity magnetic separator machine removes fine iron from the slurry, and the resulting concentrate is then sold to smelters for use in special smelting applications.

This fraction contains most of the precious metals and is then sent to the fine slag treatment plant. The nonmagnetic slurry is then treated by the Falcon gravity concentrators. The low G stage recovers fine copper, and the high G stage recovers precious metals.

Once the ash has been processed, three separate concentrates are produced and bagged. Concentrates not sold to smelters are cleaned further. Rejected particles are sent to landfills with minimal harmful metal contaminants left which can harm the environment.

For further information, contact Sepro at 1-800-990-5568 or

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