Ore Pro Microwave Technology
How does Ore Pro's technology work?
The major advantages of using microwaves for magnetite processing are:
- rapid heat transfer
- volumentric and selective heating
- energy efficiency
- compactness of equipment
- reduced CAPEX
- speed of switching on and off
- a pollution-free environment as there are no products of combustion.
The dielectric and magnetic properties of magnetite make it highly receptive to microwave heating.
- The dielectric properties characterise the response of the material to an applied external electric field.
- The magnetic permeability and magnetic loss factor characterise the response of the material to an applied external magnetic field
Microwave energy is electromagnetic radiation consisting of an electric field and a magnetic field wtih wave lengths in the range of 1 metre to 1 millimetre or a frequency range of 0.3 GHz to 300 GHz. Ore Pro's process uses industrial microwave generators with a frequency of 922 MHz.
Microwave irradiation generates heat in magnetite by two mechanisms
- Ionic Conduction
During the ionic conduction, the dissolved charged paritcles in a sample (usually ions) oscillate back and forth under the influence of the electric component of the microwave irradiation. They collide with their neighboring molecules or atoms. These collisions cause agitation or motion, creating heat. Media containing ions are efficiently heated by microwaves.
- Magnetic Rotation Hysteresis Losses
Heat generated by magnetic rotation hysteresis is attributed to the coupling of election spins in the 3d shell with the alternating magnetic field of microwaves. It changes the internal energy of magnetic material in every cycle of the microwaves, which is converted to the lattice energy (heat) through a dissipation process, namely the spin-lattice interactions.
The combination of these two mechanisms is responsible for the extremely high heating rate of the magnetite by microwave irradiation, as much as 400°C per minute.
The figure on the right shows the microwave heating profile of magnetite when exposed to the isolate electric field E, Isolated magnetic Field H and the combined electric and magnetic fields H,E. |
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Volumetric heating ensures complete oxidisation of each pellet by eliminating the formation of a hard outer shell that is sometimes common with traditional heating processes that rely on heat transfer by conduction from the exterior to the interior of the pellet.
Applying microwaves to a rotary kiln ensures continuous mixing and even heating of the pellets as they pass through the microwave energy. |
