Submerged Arc Furnace Melting of Reduced Iron With Slag Basicity Control
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Solution Overview
Problem
The use of high-grade iron ore in the direct-reduction process for producing molten pig iron is costly due to increased freight rates, and existing technologies do not efficiently utilize low-grade iron ore in submerged arc furnaces, leading to high energy consumption in the melting step.
Innovation Solution
A method for producing molten pig iron in a submerged arc furnace using reduced iron with a metallization rate of 60% or greater, adjusting slag basicity (CaO/SiO2) and carbon content (C) to enhance energy efficiency, utilizing low-grade iron ore and reducing iron scrap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-grade iron ore is used in the direct-reduction process, then the quality of reduced iron is improved, but the production cost increases due to increased freight rates
Solution Approach 1:
The invention changes the key parameter from using high-grade iron ore to using low-grade iron ore with a metallization rate of 60% or more. This parameter change allows the use of cheaper, locally available low-grade ore while still achieving high-quality pig iron through optimized melting conditions in the submerged arc furnace, including controlling basicity and carbon content
Solution Approach 2:
The invention replaces expensive high-grade iron ore with cheaper low-grade iron ore. By accepting lower initial quality of reduced iron (60% metallization rate or more) and compensating through optimized melting processes, the method uses cheaper raw materials to achieve the same final product quality
2Ease of manufacture
If low-grade iron ore is used in submerged arc furnaces, then the production cost is reduced, but the energy consumption in the melting step increases
Solution Approach 1:
The invention optimizes multiple parameters simultaneously: metallization rate (60% or more), basicity (CaO/SiO2 ratio), and carbon content. These parameter optimizations ensure that even with low-grade iron ore, the melting process achieves high energy efficiency by controlling the chemical composition and reaction conditions in the submerged arc furnace
Solution Approach 2:
The invention utilizes the porous structure and chemical composition characteristics of low-grade iron ore, optimizing the metallization rate to 60% or more. This creates a raw material with optimal properties for submerged arc furnace melting, balancing cost and energy consumption
3Device complexity
If existing technologies are used to melt reduced iron, then the process is simple, but the energy efficiency is low and operational costs are high
Solution Approach 1:
The invention optimizes critical process parameters including metallization rate (60% or more), basicity (CaO/SiO2 ratio), and carbon content. These parameter optimizations significantly improve energy efficiency in the submerged arc furnace while maintaining process simplicity and avoiding complex additional equipment
Solution Approach 2:
The invention implements parameter control and optimization based on feedback from the melting process. By monitoring and adjusting metallization rate, basicity, and carbon content, the method achieves high energy efficiency while maintaining operational simplicity through controlled parameter ranges
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
Achieves high energy efficiency in the production of molten pig iron by optimizing metallization rate, slag basicity, and carbon content, reducing energy consumption and operational costs.
Implementation Method 1
The DR process includes reducing an iron-containing agglomerate in a shaft furnace, for example, to produce direct reduced iron (DRI). An iron source raw material including such reduced iron and iron scrap, for example, is charged into an electric arc furnace (EAF) or a submerged arc furnace (SAF), for example, and then heated to be melted.
Implementation Method 2
using reduced iron with a high metallization rate can reduce the thermal energy required to melt the reduced iron
Data Source
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AI summary
Provided is a method for producing molten pig iron that can achieve high energy efficiency in a melting step of melting reduced iron in a submerged arc furnace. Specifically, the method for producing molten pig iron includes a melting step of melting, in a submerged arc furnace, an iron source raw material including reduced iron with an average metallization rate of 60% or greater to obtain molten pig iron, the melting step also including at least one or both of adding a slag forming material to adjust the basicity (CaO/SiO2) of molten slag formed on the molten pig iron, and adding a carbonaceous material to adjust the C content of the molten pig iron. Herein, the metallization rate refers to the mass percentage of a metallic iron component to the total mass of an iron component contained in the reduced iron, and the basicity (CaO/SiO2) of the molten slag refers to the mass ratio of CaO to SiO2.