Mill Reject (Pyrites) Systems

With nearly 1000+ of mill reject installations, United Conveyor has assisted customers across the globe in conveying millions of tons of mill rejects with our mill rejects and ash handling systems. Understanding how mill rejects vary from site to site, coupled with extensive experience and comprehensive laboratory testing ensure that UCC can meet the unique needs of any coal-fired plant.

Disposal of iron pyrites, rocks, tramp metal and other rejects from coal pulverizers does not have to be accomplished using a shovel and wheelbarrow.

Though the nature (size, composition, density) of mill rejects varies widely from site to site, our long history of designing superior ash handling systems and experience in comprehensive laboratory testing, ensure that UCC can recommend, design, and supply a mill rejects system to meet the individualized and unique needs of every customer.

Mill Reject (Pyrites) Systems:

  • Can run intermittently or continuously
  • Flexible design and multiple size Jetpulsion pumps to fit under pulverizer allowing for short or long distance conveying
  • Can discharge to SFC’s, dewatering bins or storage ponds
  • Can be designed to accommodate coal mill trips or sudden shutdown

  1. Are there certain advantages to using a Jetpulsion pump for conveying pyrites versus using a mechanical Pump?[+]
    Yes. A Jetpulsion pump is a self-regulation pump that contains no moving parts.
  2. We re-sell our bottom ash so how would we keep the pyrites segregated from the bottom ash? [+]

    To keep the pyrites and bottom ash separated, two separate conveying systems are required.

  3. Can UCC convey dry mill rejects? [+]

    Yes. We can convey dry mill rejects mechanically, pneumatically or hydraulically. UCC will recommend the most appropriate system type depending on unique criteria of the plant.

  4. Can a mill reject system be easily integrated? [+]

    Yes. A mill reject system can be integrated to combine the disposal of mill rejects and bottom ash.

  5. What disposal points are typically used for mill rejects?[+]

    Several disposal points can be used for mill rejects including:

    • Into a Bottom Ash Hopper where they are then conveyed out with the bottom ash
    • Into a Storage or Transfer Tank where they are conveyed separately from bottom ash
    • Into an SFC Submerged Flight Conveyor and conveyed to a final disposal point
    • Into a dedicated Dewatering Bin where bottom ash is kept separate and can be used for resale.

Ideal for converting wet sluice systems into a “dry” ash system without change to the existing bottom ash hoppers.



Mechanical chain and flight conveyor that continuously transports high temperature, dry or moist abrasive material.


Vibratory Systems

The VAX system is the latest evolution in dry bottom ash technology which delivers superior heat recovery, lower installed cost, higher reliability and less maintenance compared with conventional moving belt designs.