Composite Iron Pellets Seamless Core-Shell Structure
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Solution Overview
Problem
The ironmaking and steelmaking industry faces a high consumption rate of natural gas, necessitating the development of alternative reducing agents to reduce gas consumption while maintaining or increasing productivity.
Innovation Solution
A composite pellet with a core comprising iron ore and a carbonaceous reducing agent (3-9 wt%) and a shell of iron ore (0-3 wt% carbonaceous reducing agent) is developed, where the core and shell transition seamlessly, allowing for efficient use in direct reduced iron production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If natural gas is used as the reducing agent in ironmaking, then the reduction process is efficient, but the natural gas consumption rate is high and future availability is uncertain
Solution Approach 1:
The patent changes the chemical composition parameter of the reducing agent from natural gas (hydrocarbon gas) to solid carbon materials (coke, coal, charcoal). This substitution fundamentally alters the reducing mechanism from gas-phase combustion to solid-phase carbon reduction, thereby eliminating dependence on natural gas supply while maintaining reduction efficiency.
Solution Approach 2:
The patent employs solid carbon materials that are more abundant and cheaper than natural gas. These carbon-based reducing agents can be derived from various sources including coal and biomass, providing a more sustainable and economically viable alternative that does not suffer from the availability constraints of natural gas.
2Loss of energy
If carbonaceous reducing agents are added to the core, then natural gas consumption is reduced, but the pellet structure may become complex with visible boundaries between core and shell
Solution Approach 1:
The patent applies local quality by concentrating the carbonaceous reducing agent specifically in the core region while keeping the shell relatively free of carbon additives. This zoned distribution optimizes the reducing function in the core while maintaining a clean, simple shell structure that facilitates easy separation and avoids structural complexity.
Solution Approach 2:
The patent segments the pellet into distinct functional zones: a carbon-rich core for reduction and a carbon-poor shell for structural integrity and handling. This segmentation allows each region to perform its specific function optimally while maintaining overall pellet simplicity through clear functional differentiation.
3Ease of manufacture
If the core is dried prior to forming the shell, then the shell formation process is simplified, but the boundary between core and shell becomes visible and distinct
Solution Approach 1:
The patent performs the preliminary action of mixing the carbonaceous reducing agent with the iron ore in the core formation stage, rather than adding it later or drying the core separately. This integrated approach ensures uniform distribution of the reducing agent throughout the core while maintaining moisture levels that facilitate seamless shell formation without visible boundaries.
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
This solution reduces natural gas consumption while maintaining productivity by effectively utilizing carbonaceous reducing agents in a seamless core-shell structure, enhancing physical, mechanical, and metallurgical properties of the composite pellets.
Implementation Method 1
the current high consumption rate of natural gas and the expected future unavailability of more supporting gas has led to a greater focus on the use of alternative reducing agents as a partial replacement for natural gas. While solid carbon materials have been considered to be one suitable solution
Data Source
AI summary
Disclosed herein are methods and compositions for producing composite pellets comprising a core comprising: iron ore and a carbonaceous reducing agent; and a shell comprising: iron ore; and having a core and shell transition in a manner such that no visible boundary exists between the core and the shell in a cross-section of the pellet. The methods can be used to produce composite pellets with improved productivity and quality, and the resulting composite pellets can be used to produce direct reduced iron (DRI).