Many municipalities around the world use waste-to-energy facilities to manage non-recyclable trash. Instead of sending the waste to landfills, it’s incinerated at high temperatures, generating heat and electricity for local communities. During this process, materials like metal do not fully combust and are discharged as a mixture called “incinerator bottom ash.” This byproduct can be sorted, harvested, and then sold at a profit, creating additional revenue streams for waste facilities. 

Sepro’s Fine Slag Treatment Plant (FSTP) is a proprietary system for recovering value from fine incinerator bottom ash. It is able to recover precious and heavy metals along with an aggregate material used for road sub-base and recycled concrete. You can speak with an expert from Sepro to learn more about our FSTPs and other urban mining solutions. 

Incineration At Waste-to-Energy Facilities

Waste that enters incineration facilities is used as fuel to generate power and district heating. Steam-powered turbines are brought to life by the high temperatures and electricity is distributed to local communities. Low-energy steam is redirected to nearby buildings by insulated pipes for heating and cooling. 

After waste is incinerated, the incinerator bottom ash is collected and sent for processing. This is where an FSTP works to recover the valuable material. 

Sepro’s Fine Slag Treatment Plant

An FSTP is used in conjunction with other pieces of equipment to recover ferrous metals, aluminum, copper, gold, and other precious metals from incinerator bottom ash. The majority of incinerator bottom ash is collected for use as an aggregate material in recycled concrete or as road sub-base. Here’s how it works:

  1. Coarse material is removed using a jig or screen.
  2. The remaining particles (less than 2-4mm in size) are sent to a magnetic separator which removes fine iron particles from valuable base metals like copper and precious materials like gold or platinum. 
  3. The leftover ash is then processed by a series of gravity separators including:
    • a Sepro Slot Separator
    • a shaking table
    • a Falcon Gravity Concentrator

These separators work together to recover the precious and heavy metals from fine incinerator bottom ash

Incinerator Bottom Ash Flow Chart

Our FSTP in Austria

The Brantner  Öestereich’s incinerator bottom ash processing operation in Hohenruppersdorf, Austria uses an FSTP to recover precious metals and aggregate materials. Here are some quick stats about the facility:

  • The plant was designed, built, and delivered within 20 weeks. 
  • It has been running problem-free since 2017.
  • It processes approximately 10,000 t/a.
  • Fine particle sizes of precious metals (below 2mm) are recovered using Falcon Concentrators. 
  • 80% of the material can be used as road sub-base or as an aggregate for concrete.
  • 10% of the material is metals and minerals including copper, aluminum, and gold. 
  • 10% is discharged as a sludge containing very fine particles. There is current R&D happening to find a use for this byproduct with the goal of a zero-waste operation. 

Modifying Your Current Plant

Existing plants require no modifications to install our FSTP system. Quick delivery and installation will also have your new plant up and running quickly. Learn more about our Fine Slag Treatment Plant for incinerator bottom ash processing by contacting the experts at Sepro.