Direct Reduced Iron Production via Controlled Moisture and Particle Size
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Solution Overview
Problem
The existing methods for producing direct reduced iron require careful adjustment of moisture content in vibration mills to maintain pulverizing force, which can be challenging and affects the quality of the agglomerate, leading to variations in metallization ratio and product strength.
Innovation Solution
A method involving drying oxidized iron raw materials to a specific moisture content, mixing with a reducing material, pulverizing to a particle diameter of 150 µm to 300 µm, and adjusting moisture to 1-3% for kneading, followed by agglomeration and reduction in a rotary hearth furnace to produce high metallization ratio direct reduced iron.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If moisture content is adjusted by adding water to the raw material in the vibration mill to cover the surface of the raw material of the agglomerate with moisture, then the pulverizing force of the vibration mill is maintained, but the adjustment of moisture content becomes complex and affects the quality consistency of the agglomerate
Solution Approach 1:
The patent applies preliminary action by pre-drying the oxidized iron raw material to a specific moisture content (5-15%) before mixing with the reducing material. This preliminary moisture adjustment eliminates the need for complex moisture control during pulverization in the vibration mill, as the mixture is then pulverized without additional water addition. The pre-drying step ensures consistent pulverizing force and agglomerate quality.
2Manufacturing precision
If moisture content is adjusted by adding water during pulverization, then the surface of the raw material is covered with moisture, but the metallization ratio and product-making ratio become inconsistent
Solution Approach 1:
The patent performs preliminary drying of the oxidized iron raw material to achieve a controlled moisture content (5-15%) before mixing. This preliminary action ensures that subsequent pulverization and agglomeration proceed with consistent moisture levels, eliminating the need for water addition during pulverization and thereby achieving consistent metallization ratio and product-making ratio.
Solution Approach 2:
The patent changes the moisture content parameter of the oxidized iron raw material to a specific range (5-15%) through pre-drying. This parameter change optimizes the pulverization process and agglomerate formation, leading to improved metallization ratio and product-making ratio while simplifying operational control.
3Manufacturing precision
If the particle diameter of the mixture is reduced to 150 μm to 300 μm through pulverization, then the metallization ratio is improved, but the moisture content must be precisely controlled to maintain pulverizing force
Solution Approach 1:
The patent applies preliminary drying to control the moisture content of the oxidized iron raw material at 5-15% before pulverization. This preliminary moisture control ensures that the vibration mill maintains consistent pulverizing force throughout the process, enabling reliable production of particles within the 150-300 μm diameter range with improved metallization ratio.
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 method ensures a high metallization ratio and improved product-making ratio by controlling particle diameter and moisture content, preventing explosions and maintaining excellent kneading and granulation properties.
Implementation Method 1
drying an oxidized iron raw material selected from a group including iron ore and iron-making dust generated in an iron-making process to have a predetermined moisture content
Implementation Method 2
pulverizing the mixture obtained in the mixing step for 80% minus-sieve to have a particle diameter of 150 μm to 300 μm
Implementation Method 3
reducing the agglomerate obtained in the agglomerating step by a rotary hearth furnace to generate direct reduced iron
Data Source
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AI summary
A producing method of direct reduced iron includes the steps of: drying an oxidized iron raw material selected from a group including iron ore and iron-making dust generated in an iron-making process to have a predetermined moisture content; mixing the oxidized iron raw material subjected to the drying step and a reducing material having a predetermined moisture content to obtain a mixture; pulverizing the mixture obtained in the mixing step for 80% minus-sieve to have a particle diameter of 70 µm to 500 µm; kneading the mixture after the moisture content of the mixture subjected to the pulverizing step is adjusted; agglomerating the mixture subjected to the kneading step to be agglomerate; and reducing the agglomerate obtained in the agglomerating step by a rotary hearth furnace to generate direct reduced iron.