KR Desulfurization Stirring Paddle Casting Material
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Solution Overview
Problem
The existing casting materials for stirring paddles in molten iron desulfurization processes suffer from poor thermal shock resistance, scouring resistance, and erosion resistance, leading to short service life and increased costs due to issues like cracking, spalling, and erosion from high-temperature molten iron and desulfurizing agents.
Innovation Solution
A casting material composition comprising 60-80% M70 sintered mullite, 5-20% flint clay, 1-5% pure calcium aluminate cement, and 0.05-0.2% water-reducing agent, along with 1-5% heat-resistant stainless steel fibers, which provides enhanced thermal shock, scouring, and erosion resistance by controlling the Al2O3 content and strength ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sintered zirconia mullite and dense corundum fine powder are added to improve high-temperature strength, then scouring resistance is improved, but cost increases and thermal shock resistance deteriorates
Solution Approach 1:
The patent optimizes the particle size parameters of raw materials, specifically using silica micropowder (0-2 μm) and alumina micropowder (0-3 μm) to fill pores and refine the microstructure. This parameter optimization allows achieving high scouring resistance through improved microstructure rather than relying on expensive dense corundum, while maintaining good thermal shock resistance
Solution Approach 2:
The patent creates a composite material system combining sintered mullite (60-80%), flint clay (5-20%), silica micropowder (5-10%), alumina micropowder (5-10%), and pure calcium aluminate cement (1-5%). This composite achieves both high scouring resistance and good thermal shock resistance through synergistic effects of different materials, avoiding the need for expensive dense corundum while maintaining performance
2Temperature
If kyanite and andalusite are added to improve high-temperature stability, then refractory performance is improved, but thermal shock resistance deteriorates due to great swelling
Solution Approach 1:
The patent completely removes kyanite and andalusite from the raw material composition. Instead, it uses sintered mullite as the primary aggregate (60-80%), which provides high-temperature stability without the severe swelling problems of kyanite and andalusite, thereby maintaining both refractory performance and thermal shock resistance
3Strength
If silicon carbide is added as a principal raw material to improve scouring resistance, then abrasion resistance is improved, but cost increases and thermal shock resistance deteriorates
Solution Approach 1:
The patent replaces expensive silicon carbide with more economical materials (sintered mullite, flint clay, and micropowders) that provide sufficient scouring resistance for the application. This substitution reduces material cost while avoiding the thermal shock resistance problems associated with silicon carbide
Solution Approach 2:
The patent optimizes the particle size distribution and microstructure through using silica micropowder (0-2 μm) and alumina micropowder (0-3 μm), achieving high abrasion resistance through refined microstructure rather than relying on silicon carbide, thereby maintaining good thermal shock resistance
4Temperature
If magnesia fine powder and magnesia-alumina spinel are added to improve basicity and high-temperature performance, then refractory performance is improved, but thermal shock resistance and spalling resistance deteriorate due to great swelling
Solution Approach 1:
The patent completely removes magnesia fine powder and magnesia-alumina spinel from the raw material composition. Instead, it relies on sintered mullite (60-80%) and flint clay (5-20%) to provide high-temperature performance without the severe swelling issues, thereby maintaining both refractory performance and thermal shock resistance
5Strength
If white corundum is added to improve high-temperature strength, then scouring resistance is improved, but thermal shock resistance deteriorates and cost increases
Solution Approach 1:
The patent optimizes the particle size parameters of raw materials, using silica micropowder (0-2 μm) and alumina micropowder (0-3 μm) to refine the microstructure and achieve high scouring resistance. This parameter optimization allows replacing expensive white corundum while maintaining performance and avoiding thermal shock resistance problems
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 proposed solution significantly improves the comprehensive performance of the casting material, extending the service life of stirring paddles by 12% with reduced material costs and improved resistance to thermal shock, scouring, and erosion, thereby enhancing the desulfurization process efficiency.
Implementation Method 1
the stirring paddle is used intermittently, which requires that the casting material should have good thermal shock resistance
Implementation Method 2
60-80% of M70 sintered mullite
Implementation Method 3
1-5% of heat-resistant stainless steel fiber
Implementation Method 4
the stirring paddle rotates at high speed in high temperature molten iron, and is subject to scouring and abrasion of the molten iron
Implementation Method 5
which requires that the casting material should have good scouring resistance
Data Source
AI summary
Provided are a Kanbara Reactor (KR) desulfurization stirring paddle casting material and a preparation method therefor. The casting material consists of a base material and an additive; the base material consists of the following raw materials in weight percentages: M70 sintered mullite 60-80%, flint clay 5-20%, fine powder 5-20%, and pure calcium aluminate cement 1-5%. The percentages of each component of the additive based on the weight of the base material are as follows: water reducing agent 0.05-0.2%, and heat-resistant stainless steel fiber 1-5%. The main raw materials are M70 sintered mullite and a small amount of flint clay so as to ensure good thermal shock resistance; the medium temperature and high temperature strength are controlled at 100-180 MPa so as to ensure good erosion resistance; the content of Al2O3 in the casting material is 60-70% so as to ensure good corrosion resistance; the ratio of high temperature strength to medium temperature strength is controlled at 1-1.2, which further improves the thermal shock resistance and peeling resistance of the casting material, thereby extending the service life of the stirring paddle. The casting material is lower in cost and has a good practical furnace usage effect; in addition, a paddle blade has less chance of cracking and peeling, while a bottom portion of the stirring paddle is less eroded, thus the frequency of paddle blade repair is low, and service life is significantly improved.