Direct Reduced Iron (DRI)
a solid-state iron that has been reduced directly by removing oxygen using hydrogen and carbon monoxide derived from natural gas or coal.
Direct Reduced Iron Details
We employ direct reduced iron (DRI) in the steelmaking process. DRI can take the form of powder, pellets, lumps, and briquettes. When steelworkers remove oxygen from iron, its density decreases. This gives the metal a spongy appearance, which is why we refer to direct reduced iron as sponge iron.
To reduce iron, steelmakers consider the following methods:
- The carbothermal method of direct reduction from the ore through carbon-bearing materials. This is also the cheapest method.
- Smelt iron (pig iron) in hearths where iron ore reacts with coke. This is the most common way to reduce iron.
- Iron reduction from its ore by natural gas, beginning in the 1970s.
All effective direct reduction methods use the same process: a unique gas mixture reduces rich iron ore up to an iron content of 90%. Experts categorize the process that produces a solid with less than 90% reduction as prereduction.
Direct Reduced Iron Example
The product of the process below is direct-reduced iron (DRI). It contains about 1% carbon and 90% iron. Direct reduced iron is not suitable for producing essential metal parts, so we can only use it as a raw material in steelmaking.
· CH4+H2O=CO+Н2 (conversion of natural gas)
· FeХOY +CO=Fe+CO2
· FeХOY +H2=Fe+H2O
Industry experts prefer using the direct reduced iron method because the quality of the derived steel is very high. This is because the critical processes of Direct Reduced Iron-Hot Briquetted Iron production ensure that the levels of sulfur and phosphorus, which can be transferred from coal, are low and that there are no other impurities such as copper, lead, and zinc in the metal.
History of Direct Reduced Iron
The process became commonplace in the 1980s when the metal and mining sectors started using natural gas for iron reduction. Manufacturers proved that coal gasification products, oilwell gas, and other gaseous products were suitable for the direct reduction of iron.
In the 1990s, technological changes in the iron reduction processes significantly decreased energy consumption. This resulted in a surge in direct reduced iron production that continues to this day. A variety of techniques, equipment, and raw materials have generated a wide range of methods for direct reduced iron production, though only some of them have passed the required tests.
Significance of Direct Reduced Iron
Globally, nations aim to reduce their energy consumption. This has encouraged an unprecedented interest in the development of technologies for the production of direct reduced iron. However, it is expensive to turn all iron oxide into metal because the last stages of the process are prolonged. In addition, handling DRI requires that steelworkers work carefully to avoid oxidation or corrosion from water.
India, Venezuela, and Iran produce around 60% (41.4 million tons per year) of the global quantity of iron. However, only India and Iran have reasonable reserves of iron ore and natural gas.