In modern steelmaking, the pursuit of high-quality, high-performance steel products has driven the continuous optimization of alloy additives. Among them, 10-50mm Calcium Silicon (CaSi) Lumps have emerged as a critical multifunctional alloy, widely used in deoxidation, desulfurization, and inclusion modification. Their specific size range balances handling convenience, reaction efficiency, and cost control, making them a staple in converter, electric arc furnace (EAF), and ladle refining processes.
is a ferroalloy composed of calcium (Ca), silicon (Si), and iron (Fe), produced by smelting silica (SiO₂), limestone (CaCO₃), iron scrap, and coke in a submerged arc furnace. The "10-50mm" specification refers to the size of the alloy after crushing and screening-a range tailored to industrial needs: particles smaller than 10mm are prone to oxidation and dust loss, while those larger than 50mm melt slowly and disperse unevenly in molten steel. This size segment accounts for over 60% of calcium silicon consumption in the steel industry.
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28-35% |
Determines desulfurization and inclusion modification efficiency; >=30% for high-quality steel |
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55-65% |
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C<=0.8%, P<=0.04%, S<=0.02%, Al<=1.0% |
Avoids brittle phases (e.g., Fe₃C) and harmful inclusions; critical for low-carbon steel |
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10-50mm (>=90% within range) |
Ensures rapid melting (1400-1500℃) and uniform dispersion in molten steel |
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2.5-2.8 g/cm³ |
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Surface oxide layer <=0.5mm |
Why 10-50mm Calcium Silicon Lumps Dominate Steelmaking?
Unlike single-function additives (e.g., for desulfurization), CaSi Lumps 10-50mm integrate deoxidation, desulfurization, and inclusion modification-three core functions for high-quality steel production. Their unique advantages are amplified by the 10-50mm size:
Calcium and silicon in the alloy have strong affinities for oxygen (standard free energy of formation: CaO < SiO₂ < FeO). The dual deoxidation reaction proceeds as follows:
2Ca + O₂=2CaO (Ca rapidly captures dissolved oxygen)
Si + 2FeO=SiO₂ + 2Fe (Si removes residual FeO)
The 10-50mm size ensures the alloy melts within 2-3 minutes in a 1550-1600℃ molten pool, avoiding premature oxidation (smaller lumps) or incomplete reaction (larger lumps). Industrial data shows that using 10-50mm CaSi lumps reduces molten steel oxygen content to <=0.003%, outperforming ferro silicon alone (<=0.005%).
Calcium reacts with sulfur in molten steel to form stable CaS (melting point 2450℃), which is easily separated into slag. The reaction equation: Ca + S=CaS. The 10-50mm lumps' slow, controlled melting allows Ca to penetrate the molten pool, achieving a desulfurization rate of 60-80%-far exceeding ferromanganese (30-40%).
Harmful inclusions (e.g., angular Al₂O₃) in steel reduce toughness and weldability. 10-50mm CaSi lumps modify these inclusions into spherical CaO·Al₂O₃·SiO₂ complexes, which are less destructive to the steel matrix. For automotive sheet steel, this modification increases elongation by 8-12% and reduces weld crack rate by 90%.
Cost-Effective & Easy to Operate
The 10-50mm size is compatible with mainstream steelmaking feeding systems (ladle top charging, pneumatic conveying). Compared to calcium wire (a high-cost alternative), 10-50mm lumps reduce additive costs by 30-40% while requiring no specialized wire feeding equipment. Additionally, their low dust generation simplifies on-site environmental management.
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1. Size out of 10-50mm range; 2. Feeding too close to surface; 3. Molten steel temperature too high |
1. Screen lumps before use; 2. Use deep injection feeding; 3. Control temperature <=1600℃ |
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1. Ca content <28%; 2. Slag basicity (CaO/SiO₂) <3.0 |
1. Select high-Ca grade (30-35%); 2. Add lime to adjust slag basicity to 3.0-4.0 |
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1. Impurities in CaSi exceed standards; 2. Insufficient argon stirring |
1. Require supplier's quality inspection report; 2. Extend argon stirring to 5 minutes |
10-50mm Calcium Silicon alloy are indispensable multifunctional additives in modern steelmaking, thanks to their synergistic deoxidation/desulfurization, inclusion modification, and cost advantages. Their 10-50mm particle size is a "golden specification" that balances reaction efficiency and operational feasibility. By mastering specification verification, process optimization, and supplier selection, steelmakers can maximize the value of 10-50mm CaSi lumps to produce high-quality steel. In the low-carbon era, their upgraded versions will continue to drive the steel industry's high-quality development.
