OVERVIEW
THE PROCESS
PROCESS BENEFITS

THE PROCESS

Char production .
The reductant for the process is produced by the devolatisation of thermal coal. The volatiles (off-gases) are recovered from this stage to fire the reduction process. The devolatised coal is then milled to sub 1mm.
Recipe formulation and blending.
The fine iron oxide and milled char are added according to the required blend recipe via a weigh hopper, and mixed. The blend recipe is dependant on ore type and quality, and properties of the char (fixed carbon, reactivity).
Reduction.
The heart of the process, reduction proceeds in 2 stages – pre-heating and reduction in externally heated rotary kilns. The gaseous reduction products (primarily CO with CO2) are recovered as a process fuel.
Gas Management
Volatile gas from the coal devolatisation process is captured and ducted to the kiln burners as firing fuel for reduction heating. This gas is supplemented by the CO gas from the reduction process. Further energy saving benefit comes from proprietary technology which allows pre-heating of the combustion air using waste exhaust gases from kiln heating, resulting in the entire system being energy positive. Gas in excess of process requirements is burnt in the oxidizer and the hot exhaust gas is finally used to dry the freed ore. The net result is the entire coal devolatisation, ore drying and iron reduction processes are energy neutral, with the only electricity required for the process being for lighting, motors and instrumentation.
Cooler.
The reduced Fe powder is cooled to approximately 80°C under reducing conditions to prevent re-oxidation, before further treatment.
Magnetic separation.
This beneficiation step of the reduced Fe powder removes excess carbon and ash and some gangue associated with the ore, giving a higher total and metallic Fe content in the product. Recovered carbon is recycled into the reductant feed.
Final product options.
The reduced iron powder can now be i) melted directly by feeding into a an appropriate melting unit and granulated or ii) briquetted for use as a feedstock into traditional electric steelmaking processes. Depending on requirements, the product can be hot or cold briquetted – the final form being a HBI or DRI product.

 


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