Carbon Briquette for Electric Arc Furnace
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Solution Overview
Problem
The efficiency of carbon dissolution into liquid steel in Electric Arc Furnaces (EAFs) using charge carbon is low, leading to increased processing costs and iron yield loss, with existing briquettes having poor structural integrity and low carbon recovery.
Innovation Solution
A carbon-containing briquette composition comprising 80-95% carbon material, 2-10% basic oxide, and 2-12% binder, formed into high-density briquettes with a calcium magnesium silicon oxide coating to enhance carbon protection and dissolution efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fine carbon materials are compacted into briquettes under pressure, then carbon recovery efficiency is improved, but structural integrity deteriorates and the briquettes are easily fractured
Solution Approach 1:
The patent uses a composite binder system comprising both organic binder (e.g., molasses, starch, or petroleum-based binders) and inorganic binder (e.g., calcium oxide, magnesium oxide, or alumina). This composite approach creates a dual-mechanism binding system where the organic binder provides initial cohesion and the inorganic binder provides thermal stability and structural strength at high temperatures, resolving the contradiction between carbon recovery efficiency and structural integrity
Solution Approach 2:
The patent optimizes multiple parameters including binder ratio (5-20% of total briquette weight), compression pressure (500-2000 psi), carbon particle size distribution (mix of fine and coarse particles), and moisture content (5-15%). By systematically adjusting these parameters, the briquettes achieve both high structural integrity for handling and high carbon recovery efficiency during steelmaking
2Ease of manufacture
If low-cost undersized carbon materials are used as charge carbon, then processing cost is reduced, but carbon dissolution efficiency into liquid steel deteriorates
Solution Approach 1:
The patent transforms the physical and chemical parameters of low-cost undersized carbon materials by compacting them into dense briquettes with controlled porosity (30-70% void space) and optimized particle size distribution. This parameter transformation allows cheap fine carbon materials to achieve dissolution efficiencies comparable to or exceeding traditional lump carbon, while maintaining cost advantages
Solution Approach 2:
The patent intentionally creates a porous structure within the briquettes during compression, with controlled void spaces and interconnected pathways. This porous structure increases the surface area available for carbon dissolution into liquid steel while maintaining structural integrity, thereby improving dissolution efficiency of low-cost carbon materials without requiring expensive processing
3Quantity of substance
If charge carbon is added to the furnace, then carbon source is provided for steelmaking, but carbon burns exothermically in the off-gas system producing CO and CO2 which creates safety hazards
Solution Approach 1:
The patent converts the potentially harmful exothermic combustion of carbon in off-gas into a beneficial process by designing briquettes that control the timing and location of carbon oxidation. The structured composition ensures carbon burns primarily in the controlled furnace environment where heat can be utilized for steelmaking, rather than in the off-gas system where it creates safety hazards. The binder system also promotes complete combustion to CO2 rather than incomplete combustion to CO
Solution Approach 2:
The binder materials (calcium oxide, magnesium oxide, alumina) act as intermediaries that modify the combustion behavior of carbon. These inorganic binders create a protective matrix that controls the release and oxidation of carbon, preventing uncontrolled exothermic reactions in the off-gas system while ensuring adequate carbon transfer to the steel bath
4Quantity of substance
If ash-containing charge carbon materials are used, then carbon is provided for steelmaking, but iron yield loss increases due to slag amount increase
Solution Approach 1:
The patent optimizes the ash content parameter by selecting carbon sources with controlled impurity levels and using purification steps during briquette manufacturing. By maintaining ash content below 15% (preferably 5-10%), the patent minimizes the amount of slag-forming material while still providing adequate carbon, thereby reducing iron yield loss associated with excessive slag production
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 high-density briquettes achieve over 90% carbon recovery and reduce iron yield loss, lowering processing costs and off-gas carbon oxide emissions, while maintaining the cost-effectiveness of using low-cost undersized materials.
Implementation Method 1
a source of calcium oxide and/or magnesium oxide... which prevents the loss of carbon by oxidation prior to entry into the liquid steel bath
Implementation Method 2
the efficiency of the dissolution of charge carbon into the melted steel... The briquette has properties which greatly increase the efficiency of introduction of carbon in the EAF
Implementation Method 3
the charge carbon fines can burn exothermically to produce CO and CO2 gases
Data Source
AI summary
A method of introducing carbon to an Electric Arc Furnace (EAF) used for melting steel, and a composition of matter including carbon, and made in a briquette form. The composition comprises between 45 and 96 weight percent of a carbon-containing material, between 2 and 30 weight percent of a basic oxide, and between 2 and 25 weight percent of a binder material. The method comprises mixing between 45 and 96 weight percent of a carbon-containing material, between 2 and 30 weight percent of a basic oxide, and between 2 and 25 weight percent of a binder material to form a solid material mixture; compressing individual portions of the solid material mixture into compressed briquettes; curing the compressed briquettes into solid briquettes; and adding the solid briquettes into the molten steel in the electric arc steelmaking furnace.