Processed DRI Surface Abrasion and Oil Coating
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Solution Overview
Problem
Direct reduced iron (DRI) is challenging to transport and store due to its high reactivity with oxygen and moisture, leading to oxidation, rusting, and combustion, which increases costs and limits its production to locations near steelmaking facilities.
Innovation Solution
A method involving tumbling DRI in a rotatable chamber with a screen to remove fines and abrade the surface, followed by oil application and potential binder addition to enhance compressive strength and reduce reactivity, resulting in a processed DRI with improved stability and transportability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DRI is transported and stored in bulk, then it enables economical production locations away from steelmaking facilities, but it reacts with oxygen and moisture causing oxidation, rusting, and combustion
Solution Approach 1:
A hydrocarbon oil coating is applied to the DRI pellets to serve as an intermediary barrier between the reactive DRI surface and the oxidizing atmosphere. The oil layer prevents direct contact between oxygen/moisture and the DRI, eliminating the harmful reactions while allowing the DRI to be transported and stored in bulk over long distances
Solution Approach 2:
The hydrocarbon oil coating creates an inert protective environment around each DRI pellet surface. This oil layer acts as a physical barrier that excludes oxygen and moisture from the DRI surface, effectively creating a localized inert atmosphere that prevents oxidation and combustion during transportation and storage
2Reliability
If DRI is produced near steelmaking facilities, then transportation risks are reduced, but production locations are limited and costs increase
Solution Approach 1:
The DRI pellets are pre-coated with hydrocarbon oil immediately after production to establish protective coverage before transportation begins. This preliminary protective action ensures that the DRI is already protected against oxidation and combustion risks, enabling safe transport from remote production locations to steelmaking facilities without compromising reliability
3Area of moving object
If DRI surface is rough and porous, then it has high surface area exposed to atmosphere, but this increases reaction with oxygen and moisture
Solution Approach 1:
The hydrocarbon oil coating serves as a mediator that covers the rough, porous DRI surface completely. Rather than trying to change the DRI surface morphology, the oil layer provides a smooth, non-reactive outer surface that prevents oxygen and moisture from accessing the high-surface-area DRI material underneath, thereby preventing oxidation and rusting
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The processed DRI exhibits reduced surface roughness, increased compressive strength, and decreased reactivity, allowing for safer and more economical long-distance transportation and storage, thereby increasing its usefulness in steelmaking.
Implementation Method 1
rotating the chamber to tumble the DRI on the screen in the chamber while the DRI moves through the chamber from the feed end to the exit end, thereby removing fines from the DRI
Implementation Method 2
applying oil to the processed DRI
Data Source
Figure 1~3
Figure 4A~4C
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AI summary
A processed DRI material having an average surface roughness (Ra) of less than 1.5 μm is disclosed. A method and system for making processed DRI are also disclosed. One embodiment of the method and system may include assembling a rotatable chamber having an internal screen capable of supporting DRI during tumbling, with at least one opening in the chamber to permit fines to exit the chamber during tumbling, and delivering DRI into the chamber to tumble the DRI on the screen to remove fines from the DRI. Another embodiment of the method and system may include assembling a rotatable chamber having a feed end and an exit end, and having a screen therein capable of supporting DRI as the DRI moves through the chamber, and delivering DRI to the chamber and rotating the chamber to tumble the DRI while removing fines.