Design and performances of a screw dryer heated using electromagnetic induction

CIM Montreal 2007
Michel Dostie, Sylvain Lahaie, Yves Fontaine, Sébastien Boivin,
Abstract A screw dryer heated by electromagnetic induction was developed and installed at Mines Niobec to dry a niobium concentrate. This dryer allows to achieve a reduction of the dust and green house gases emissions at the plant. It offers an easy control, an improved energy efficiency and it can be used to dry granular materials, powders and others products usually dried in a rotary dryer or in a screw dryer using a thermal fluid.

The operating principle is fairly simple. Three inductors operated at the frequency of the electric network heat the metallic parts of the dryer including the screws used to move the product inside the dryer. Heat transfer to the product occurs through its contact with the metallic parts. The design of such a dryer requires a balance between the needs related to the induction heating, and those associated with contact heat transfer and product transportation inside the dryer.

This first industrial implantation has involved significant development efforts and has required the collaboration of all parties. This paper will review the design process, some problems encountered and the performances achieved.
Keywords: Drying, niobium oxyde, screw conveyor, screw dryer, induction heating
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