Environment-friendly Corex process of iron and steel making:
The highlight of the process is it does not require coking coal. The process differs from the conventional blast furnace route; where un-treated non-coking coal can be directly used for ore reduction and melting work, eliminating the need for coking plants. The use of lump ore or pellets also dispenses with the need for sinter plants.
The ability to operate without coke gives this process two environmental advantages over the conventional blast furnace. First, because coke ovens are not needed, all of the problems associated with the generation of benzene and other coal tar byproducts are eliminated. Second, the dust problems associated with blast furnaces are also eliminated because the off-gas is used as fuel. This process along with direct reduction of iron (DRI) process is being implemented in many countries. The off-gas obtained being used to fuel the adjoining DRI plant.
Viewing the process from the coal-route perspective, non-metallurgical coal is directly charged into the melter gasifier. Due to the high temperatures predominating in the dome of the melter gasifier (in excess of 1000 °C), a portion of the hydrocarbons released from the coal during devolatilization are immediately dissociated to carbon monoxide and hydrogen. Undesirable by-products such as tars and phenols, etc. are destroyed and therefore cannot be released to the atmosphere. Combustion with oxygen injected into the melter gasifier results in the generation of a highly efficient reduction gas. Hot metal and slag tapping are carried out as in conventional blast furnace practice. The quality of the hot metal is equivalent to that produced in a blast furnace.
Environmental Aspects: In this system emissions contain only insignificant amounts of NOx, SO2, dust, phenols, sulphides and ammonium. Emission values already exceed by far future European standards. Also, waste-water emissions from are far lower than those in the conventional blast-furnace route. These environmental features are additional key reasons for the attractiveness of the present system.
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