Blast Furnace Ore Phase Control for Higher Gaseous Reduction
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Solution Overview
Problem
Existing blast furnace processes face challenges in reducing CO2 emissions due to stagnation of gaseous reduction reactions in agglomerated ore, which are not effectively addressed by existing methods that focus on high-temperature conditions or sintered ore properties, limiting the efficiency of gaseous reducing agents like hydrogen.
Innovation Solution
A blast furnace operating method that adjusts the amount of gaseous reducing agent to 100 Nm3/t or more and controls the phase fraction of calcium ferrite and secondary hematite phases in the agglomerated ore within specific ranges to enhance gaseous reduction, minimizing the use of solid reducing agents and reducing CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If gaseous reducing agent (hydrogen) is blown into the blast furnace to increase gaseous reduction degree, then CO2 emissions can be reduced, but the reduction reaction stagnates when reduction degree reaches 70% due to microstructure impeding gaseous reduction
Solution Approach 1:
The patent changes the chemical composition parameters of the agglomerated ore by controlling the phase fraction of calcium ferrite (40-70% by volume) and secondary hematite (10-40% by volume). This parameter optimization prevents the formation of microstructures that impede gaseous reduction, allowing the reduction reaction to proceed beyond the typical 70% stagnation point and achieve higher reduction degrees (80-90%), thereby reducing CO2 emissions while maintaining high productivity
Solution Approach 2:
The patent creates a composite microstructure within the agglomerated ore by controlling the distribution and fraction of different phases (calcium ferrite, secondary hematite, and other mineral phases). This composite structure prevents the formation of continuous metallic iron shells that block gas diffusion, enabling sustained gaseous reduction throughout the ore particle while reducing reliance on solid carbon reducing agents and associated CO2 emissions
2Object-generated harmful factors
If the proportion of smelting reduction by solid reducing agent (carbon) is reduced to lower CO2 emissions, then the proportion of gaseous reduction must be increased, but gaseous reduction stagnates due to microstructure formation
Solution Approach 1:
The patent optimizes the chemical composition parameters of the agglomerated ore, specifically controlling the phase fraction of calcium ferrite (40-70% by volume) and secondary hematite (10-40% by volume). These parameter changes prevent the formation of microstructures that impede gaseous reduction, ensuring reliable and complete reduction reactions even when relying primarily on gaseous reducing agents rather than solid carbon, thereby achieving both low CO2 emissions and high reduction completeness
Solution Approach 2:
The patent implements a feedback mechanism by monitoring and controlling the phase composition of the agglomerated ore before charging. By ensuring the calcium ferrite and secondary hematite phases are within specified ranges, the process feedback prevents the formation of stagnation-inducing microstructures, guaranteeing reliable gaseous reduction progression and complete ore reduction while minimizing CO2 emissions from solid carbon consumption
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 method increases the gaseous reduction degree, reducing CO2 emissions by optimizing the phase fractions of calcium ferrite and secondary hematite phases, thereby enhancing the efficiency of the blast furnace process.
Implementation Method 1
The first process is gaseous reduction by a gaseous reducing agent such as CO or hydrogen
Implementation Method 2
The second process is smelting reduction by carbon (C) in coke used as a solid reducing agent
Data Source
Figure 1~2
Figure 3~4
AI summary
Provided is a blast furnace operating method with which CO2 emissions can be reduced. In the blast furnace operating method, molten pig iron is produced by charging agglomerated ore into the blast furnace from the top and supplying a gaseous reducing agent from a lower portion of the blast furnace. The amount of the gaseous reducing agent supplied is adjusted to 100 Nm3/t or more, and the phase fraction of a calcium ferrite phase or a secondary hematite phase in the agglomerated ore is adjusted within a prescribed range.