If your waste-to-energy facility is using a dry processing system to recover metals from incinerator bottom ash, you’re missing out. 

Dry processing incinerator bottom ash is unable to effectively treat fine size fractions smaller than 2mm. And since 20-30% of ash is finer than 2mm, any fine precious metals, along with copper, zinc, and lead, are not recovered. With a simple modular plant addition to any dry processing system, you could increase your overall metal recovery, speed up the entire process, and lower your operational footprint. 

We’ve analyzed both wet and dry treatments of incinerator bottom ash and have five reasons why wet processing ash is the superior option. For more information on how to improve your metal recovery, contact Sepro Urban Mining

Wet Processing Is Faster Than Dry Processing

Dry processing incinerator bottom ash involves a 4-6 week aging period. During this time, the moisture content of the ash is reduced from approximately 25% to 10%, and metals within it oxidize. This lengthy process is necessary for effective metal recovery to take place. 

Wet processing eliminates this aging period. Instead of drying out the ash, it’s completely submerged in water while a mineral jig separates particles according to their density. The jig recovers heavy non-ferrous metals and separates floats, organics and unburnt material from the ash. The removal of water-suspended slimes from the ash allows for fine metal recovery from incinerator bottom ash. 

Eliminating the aging period also allows for the next benefit of wet processing of incinerator bottom ash. 

Wet Processing Increases Throughput

Instead of incinerator bottom ash taking up space as you wait for it to dry, you can immediately start processing it. With no delays, you can increase your operations throughput, creating a more efficient metal recovery system. A bonus here is that considerably less storage area is required! 

Wet Processing Incinerator Bottom Ash Makes Fine Size Metal Recovery Possible

There is no meaningful metal recovery from the fine size fractions in a dry process. Most valuable particles up to 2mm in size remain unliberated or respond poorly to eddy current separators. In most waste-to-energy facilities, fine particle sizes end up in tailings and become lost revenue opportunities. 

During wet processing of incinerator bottom ash, fine particles less than 2mm can be recovered. A system of jigs, slot separators, gravity concentrators, and magnetic separation devices ensures optimal recovery of fine precious metals. 

Wet Processing is Dust Free

Dust generation is eliminated because fine sizes are kept in a wet environment and coarse sizes also remain moist. This limits any material buildup on chutes, conveyors, and other pieces of processing equipment. 

A dust-free environment is also beneficial for any workers handling incinerator bottom ash or processing equipment. 

Wet Processing Creates Better Aggregate Material

A secondary objective of wet processing of incinerator bottom ash is to use coarse particles to make construction aggregate. The wet processing of particles larger than 2mm shows significantly better chemical and physical properties in regards to environmental and aggregates applications versus dry treatments. This allows the aggregate ash material to be used in areas with strict environmental restrictions.

Wet processing also removes the need to mine virgin aggregate material and reduces the amount of incinerator bottom ash sent to landfills. 

Contact Sepro Urban Mining to Learn More

Wet processing incinerator bottom ash allows for higher resource recovery, a lower footprint, minimized dust emissions and the ability to produce quality construction aggregates. To speak with an expert about increasing metal recovery from incinerator bottom ash, contact Sepro Urban Mining.