Arc Resistance Steelmaking for Low-Nitrogen Converter Refining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing steel production methods, namely the blast furnace-converter route and electrical steel route, face challenges in reducing CO2 emissions and efficiently removing trace elements like nitrogen, particularly in producing low-nitrogen crude steel for ULC and IF steel grades, with the electrical steel route requiring complex downstream secondary metallurgy.
Innovation Solution
A process involving a melting furnace with arc resistance heating followed by a converter, where metallic melt is refined with oxygen and inert gas to form CO bubbles, effectively reducing nitrogen content to below 50 ppm, while maintaining a reducing atmosphere to minimize CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the blast furnace-converter route is used to produce low-nitrogen crude steel, then the nitrogen content can be reduced to below 50 ppm, but CO2 emissions increase significantly
Solution Approach 1:
The patent changes the operational parameters of the converter process by controlling the oxygen blowing regime and carbon content to achieve nitrogen removal below 50 ppm. This allows the electrical steel route to produce low-nitrogen crude steel without requiring the blast furnace route, thereby reducing CO2 emissions while meeting the nitrogen content requirement
Solution Approach 2:
The patent converts the typically harmful high nitrogen content resulting from electrical steelmaking into a benefit by using the converter's oxygen blowing process to remove nitrogen. The oxygen that would normally increase nitrogen pickup is instead controlled to achieve nitrogen removal through oxidation and slagging, turning a disadvantage into an advantage
2Object-generated harmful factors
If the electrical steel route is used to produce crude steel, then CO2 emissions are reduced, but the removal of elements having oxygen affinity and impurities is less efficient
Solution Approach 1:
The patent uses strong oxidation in the converter by blowing oxygen through the metallic melt to efficiently remove elements having oxygen affinity (carbon, silicon, manganese, phosphorus) and impurities. This accelerated oxidation process achieves impurity removal levels comparable to or exceeding the blast furnace-converter route, while maintaining the CO2 emission advantages of electrical steelmaking
Solution Approach 2:
The patent uses slag as an intermediary to remove impurities. The oxidized elements form compounds that are transferred to the slag phase, which is then separated from the steel. This intermediary mechanism enables efficient impurity removal while maintaining the benefits of the electrical steel route
3Manufacturing precision
If complex downstream secondary metallurgy methods are used in the electrical steel route to reduce trace elements, then the nitrogen content can be reduced, but the process complexity increases
Solution Approach 1:
The patent merges the nitrogen removal function into the primary converter refining process itself, rather than requiring separate downstream secondary metallurgy steps. By controlling the oxygen blowing and chemical reactions in the converter, nitrogen is removed as part of the main refining operation, eliminating the need for additional complex equipment and process steps
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 process achieves low-nitrogen crude steel with reduced carbon content, suitable for ULC and IF steel grades, without the need for additional capital investments or process recertification, and reduces CO2 emissions by using a melting furnace with arc resistance heating instead of a blast furnace.
Implementation Method 1
melting directly reduced iron and/or scrap in a melting furnace with arc resistance heating, especially with a reducing atmosphere
Implementation Method 2
melting furnace with arc resistance heating
Implementation Method 3
refining the metallic melt in the converter to give liquid crude steel... the metallic melt is refined with oxygen
Implementation Method 4
refining with oxygen and inert gas to form CO bubbles, effectively reducing nitrogen content
Data Source
AI summary
The invention relates to a process for producing low-nitrogen crude steel. This process includes melting directly reduced iron and/or scrap in a melting furnace with arc resistance heating to give a metallic melt and a slag. The metallic melt is removed from the melting furnace and used to charge a converter. The metallic melt is refined in the converter to give liquid crude steel. The liquid crude steel is tapped having a nitrogen content [N] of not more than 50 ppm, especially of not more than 30 ppm.