Molten Iron Refining with Cold Iron Source Dissolution
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Solution Overview
Problem
Current methods for increasing the production of molten steel per unit mass of molten iron in steel production face challenges in efficiently dissolving cold iron sources without increasing energy consumption and greenhouse gas emissions, and existing techniques for desiliconization and dephosphorization are inefficient and costly.
Innovation Solution
A refining method involving charging molten iron and a cold iron source into a converter type refining vessel, using a silicon-containing material and CaO as a slag-forming agent, with intermediate slag removal to maintain optimal slag basicity and temperature for efficient desiliconization and dephosphorization, allowing for continuous processing and reduced energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dephosphorization is conducted as preliminary treatment before decarburization refining in the converter, then phosphorus removal efficiency is improved and cost is reduced, but silicon is consumed by oxidation and carbon concentration decreases by about 1.5 mass%, leaving no thermal room for dissolving cold iron source
Solution Approach 1:
The patent applies preliminary dephosphorization treatment to the molten iron before decarburization refining in the converter. By conducting dephosphorization as a preliminary action, phosphorus is removed in advance when the molten iron is in a suitable temperature range, improving phosphorus removal efficiency while managing thermal conditions for subsequent cold iron source dissolution
Solution Approach 2:
The patent controls the temperature parameter of molten iron during dephosphorization to optimize the process. By maintaining appropriate temperature parameters during preliminary dephosphorization and then managing the thermal conditions during decarburization, the process achieves both effective phosphorus removal and creates thermal room for cold iron source dissolution through parameter optimization
2Productivity
If cold iron source such as iron scrap is compounded into molten iron in the converter, then production amount of molten steel is increased, but energy consumption and greenhouse gas emission increase
Solution Approach 1:
The patent converts the harmful effect of cold iron source addition (temperature drop) into a beneficial process by utilizing the exothermic oxidation reactions during decarburization refining. The heat generated from carbon oxidation and other exothermic reactions is used to melt and dissolve the cold iron source, thereby increasing molten steel production while minimizing additional energy consumption and greenhouse gas emissions
3Productivity
If dephosphorization and decarburization refining are conducted simultaneously in the converter, then cold iron source can be compounded, but cost increases and slag generation increases
Solution Approach 1:
The patent separates dephosphorization as a preliminary treatment step before decarburization refining in the converter. This sequential approach allows dephosphorization to be completed with optimized conditions, then enables cold iron source compounding during the subsequent decarburization stage, achieving cost-effectiveness by avoiding simultaneous process complexity while maintaining productivity
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 enables efficient and cost-effective dissolution of a large amount of cold iron source in a short time, reducing energy consumption and greenhouse gas emissions, while minimizing equipment and energy requirements, and optimizing the refining process.
Implementation Method 1
supplying an auxiliary material containing CaO as a main component together with an oxygen source to dissolve the cold iron source and at the same time conduct desiliconization of the molten iron
Implementation Method 2
using a silicon-containing material and CaO as a slag-forming agent, with intermediate slag removal to maintain optimal slag basicity and temperature for efficient desiliconization and dephosphorization
Implementation Method 3
a silicon-containing material or a combination of a silicon-containing material and a carbon material is added as a heat source to the converter type refining vessel in the desiliconization
Data Source
AI summary
In a molten iron refining method by charging molten iron and a cold iron source into a converter type refining vessel, supplying a material containing CaO with an oxygen source dissolving the cold iron source and conducting molten iron desiliconization, removing at least a part of the produced slag as an intermediate slag removal, and supplying a slag-forming agent and an oxygen source to the molten iron for dephosphorization, a silicon-containing material or a combination of it and carbonaceous material is added in the desiliconization then carried out under conditions such that the slag basicity (mass % CaO/mass % SiO2) in the desiliconization completion is more than 0.5 but less than 1.5 and a molten iron temperature in the desiliconization completion is more than 1280° C. but less than 1350° C. and more than 30 mass % of the slag produced in the desiliconization is removed from the vessel in the intermediate slag removal.