We explain the advantages of DRI charging in steelmaking furnace in this section.
Advantages of Utilizing Direct Reduced Iron (DRI) in Steel Production Furnaces
Advantages of Utilizing Direct Reduced Iron (DRI) in Steel Production
- Minimal presence of impurities.
- Consistent and reliable chemical composition.
- Adjustable carbon levels.
- More manageable compared to scrap metal.
- Allows for constant feeding into the furnace.
- Enhanced slag foaming properties.
- Regulated nitrogen content in the steel.
- Uniform melting process.
STORAGE, HANDLING AND LOADING OF DRI
Thermocouples are strategically positioned for surveillance throughout the journey (TC1 to TC5). Once 50-100% of the load is aboard, ASE STEEL Group adds a second set of thermocouples in each hold (TC6 to TC9).
For post-loading nitrogen purging, steel pipes featuring perforations are laid on each hold’s floor (minimum diameter of 50 mm, with 10 mm holes at 150 mm intervals).
Upon loading completion, two lines for gas sampling are fitted—one for oxygen (O2) and another for hydrogen (H2) detection. The O2 line is positioned above the cargo, while the H2 line just beneath the hatch cover.
All hatches are sealed using Marine/ramnek tape along openings and seams, with ventilators securely closed and covered. Additionally, the application of Polypropylene foam is advised to further ensure the holds are sealed.
Nitrogen (N2) is circulated through the steel pipes in each hold to replace the air and establish an inert environment.
Once the hold is inerted, the N2 supply is disconnected, and the entry point is sealed, with O2 levels around 2-3%.
For the journey, ASE STEEL Group must provide a separate ISO-tank with nitrogen and a vaporizer to sustain low oxygen levels by occasionally topping up the holds as needed.
A supercargo is present on all DRI voyages to guarantee the safety and stability of the cargo at sea, with responsibilities including monitoring, recording, and reporting on temperature, O2, and H2 levels.
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Container Shipment
DRI can be transported in 20ft containers. For small orders and short trips under favorable environmental conditions, ASE STEEL offers DRI in 1 Ton Jumbo Bags for container stuffing and loading. For pricing and additional costs for large bag packaging of Direct Reduced Iron (DRI – Sponge Iron), contact ASE STEEL.
Steel industry
The steel sector stands as a significant contributor to greenhouse gas emissions, demanding considerable energy. Presently, the predominant method for steel production is the coal-coke-based blast furnace-basic oxygen furnace (BF-BOF) pathway, responsible for emitting roughly two tonnes of CO2 for every tonne of steel produced.
This review highlights key technologies, recent advancements, challenges, and a technoeconomic analysis of steelmaking methods, with a focus on integrating hydrogen into both new and traditional iron and steel production processes.
Notably, experiments, particularly in Germany, are in progress to substitute coal with hydrogen in the blast furnace’s tuyeres. Yet, it remains uncertain whether this method can surpass a 30% coke replacement due to technical hurdles.
Direct smelting and fluidized bed approaches have the potential to reduce CO2 emissions by 20%-30% even without carbon capture and storage. The role of hydrogen as an alternative to natural gas and coal in these processes has not been fully determined.
Currently, the most advanced technology is the hydrogen-based direct reduction of iron ore (DRI) coupled with melting steel scrap in an electric arc furnace (EAF), which could cut CO2 emissions by up to 95%, contingent on the supply of high-grade iron concentrates.
Shaft furnace methods dominate DRI production, accounting for more than 72% of total output, initially designed to use natural gas as the primary fuel and reducing agent. These methods are now transitioning to use hydrogen predominantly, aiming to yield a low-carbon DRI.
Plasma and electrolysis-based iron and steel production represent other prospective hydrogen applications, with the potential to reduce CO2 emissions by over 95%.
However, these technologies are still in early development stages, with a technology readiness level under 6.
The adoption of hydrogen in steel production faces numerous challenges, including heat distribution due to the endothermic nature of the H2 reduction process, managing the carbon content in steel (especially when using zero-carbon DRI), extracting gangue materials, and obtaining competitively priced renewable hydrogen and high-grade iron ore (>65% Fe).
With the global decline in iron ore quality, some companies are exploring the pre-melting of DRI prior to steel production, potentially employing submerged arc technology to remove gangue materials.
Therefore, extensive laboratory and pilot-scale testing are essential to evaluate process parameters and product quality. It is projected that hydrogen will significantly contribute to the decarbonization of the steel industry by 2035.
Incorporating hydrogen into the steel industry presents several hurdles. Calculations suggest that approximately 104.0 kg of hydrogen per tonne of steel is necessary to fully substitute the energy derived from the traditional coal-coke-based BF-BOF method.
A facility producing 1.0 Mt/y of steel would need about 104.0 kt/y of hydrogen, which translates to 11.87 tonnes of H2 per hour or 141,757 cubic meters of H2 per hour. To fully reduce one tonne of iron ore (Fe2O3), 54.0 kg of H2 is required stoichiometrically.
It is also estimated that an electrolyser with a minimum capacity of 600 MW would be needed to produce this quantity of hydrogen, assuming an electrolyser efficiency of 70%.
Efforts are in progress to adopt hydrogen as both a fuel and a reducing agent, aiming to phase out fossil fuels. Nonetheless, there are numerous technical and economic issues that must be resolved to make hydrogen-based methods widely accepted in the steelmaking sector.
The procurement of high-quality iron ore is increasingly difficult as the quality of ore rapidly deteriorates globally.
Consequently, the production of DRI is likely to utilize lower-quality iron ore, leading to a rise in gangue material and incomplete metallization during processing, posing further complications. From 2000 to 2009, there was a decline of about 4.0% in the average iron content of iron ore worldwide.
Iron and steel producers have disclosed varying data on energy use, environmental effects, and cost efficiency. These metrics are compiled in Table 2 from diverse sources.
The average energy usage for the BF-BOF method is around 25.0 GJ/tls, with the blast furnace (BF) accounting for roughly half of this consumption.
It’s important to note that the figures for shaft furnace and smelting reduction methods pertain solely to iron production and aren’t directly comparable to the BF-BOF statistics.
Energy usage for various shaft furnace technologies ranges from 12 to 13 GJ/tls, which is in line with the BF process. Except for HIsarna, which is noted to be 30% more energy-efficient, the smelting reduction method generally.
consumes more energy than the BF process. In terms of steel production, the energy demand for DRI, plasma, and electrolysis-based methods is significantly less than that of the BF-BOF pathway.
