Screw classifier for unburned slag

Screw conveyor classifier for unburned slag. The screw conveyor is designed to initially force material down into a water-filled bin, then elevate it using a separate screw rotor for transport and drainage.

The screw conveyor classifier is used for unburned slag in a waste burning plant.

The process is used to cool down material that have been through a heating process once, but have not been incinerated. To prevent smoldering or uncontrolled fires, the material is submerged in a water-filled bin for soaking and cooling.

What is a screw classifier?

• A screw classifier is used to seperate or sort material, using a water filled compartment
• Materials to process in a screw classifier can be f.x. minor minerals, water cooled ash or slags from a boiler in a powerplant
• Different material, have different densities, which therefor can be sorted easier in a Water filled bin

Main features of this screw classifier

• The material will be forced down in an angle, by a smaller screw rotor. It will release the material underneath a water line. Another screw rotor will catch it and transport it upwards in an opposite angel for transport, sorting and drainage.
• The inlet house and transport pipe are designed water tight , as the water level will be approx. 2/3 of the height.
• There are several drainage, outlet points in the inlet house – flange bolted joints
• FAT test has been made, together with customer, with live test on site.

BEMA has made the design and assembly all together for the client to receive a complete and ready to run machine. The connection joints are specifically placed to make installation easy  with existing equipment on customers site.

In the design process BEMA has visited the waste burning plant and assisted in measuring on the existing location. This saves the customer cost for re-build and fitting, when the final machine arrives.

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FAQ – Screw classifier for unburned slag

What is a screw classifier used for?

A screw classifier is designed to separate or sort materials in a water‑filled compartment. It is commonly used for handling minor minerals, water‑cooled ash or unburned slag from boilers in power or waste‑burning plants, where different material densities allow efficient separation.

How does this screw classifier handle unburned slag?

The classifier forces the material downward into a water‑filled bin using a smaller screw rotor, ensuring the slag is submerged for cooling and smolder‑prevention. A second screw rotor then lifts the material in the opposite direction for transport, sorting and drainage. The inlet housing and transport pipe are watertight to maintain the required water level.

What are the key advantages of this design?

The machine is fully designed and assembled by BEMA, including watertight construction, multiple drainage outlets and connection joints placed for easy installation with existing equipment. A full FAT test was performed with the customer, ensuring the classifier arrived ready to run and fit seamlessly into the plant setup.