Calcium silicon (CaSi) powder is a widely applied composite ferroalloy in modern metallurgy. It delivers integrated functions of deep deoxidation, molten steel desulfurization, inclusion modification, and graphite refinement for cast iron. Compared with calcium silicon lumps, CaSi powder features a larger specific surface area, faster metallurgical reaction speed, and higher element recovery rate, making it ideal for automated feeding, pneumatic injection, and cored wire manufacturing.
However, improper selection of chemical grade, size, impurity limits and bulk density will lead to severe issues: excessive oxidation loss, unstable calcium recovery, nozzle clogging, casting shrinkage, high production costs and inconsistent final metal quality.
Metallurgical engineers, foundry procurement managers and ferroalloy buyers must match silicon calcium powder specifications strictly according to furnace types, feeding methods and end-product requirements.
Core Factors to Evaluate Before Selection
Before confirming orders, evaluate four critical indicators of SiCa powder:
Chemical Grade (Si & Ca content)
Calcium determines desulfurization and inclusion modification capacity; silicon supports continuous deoxidation.
Impurity Control (Al, C, P, S)
Low aluminum powder is mandatory for high-cleanliness steel; low phosphorus & sulfur specifications are required for pipeline steel, ductile iron and automotive steel.
Size Distribution
The most overlooked parameter. Particle range directly affects reaction rate, anti-oxidation performance and feeding system compatibility.
Production Process & Feeding Method
Powder injection, cored wire filling, ladle inoculation and briquetting all require distinct sizing and purity standards.
Main Commercial Grades of Calcium Silicon Powder
| Grade | Si (Min, %) | Ca (Min, %) | Al (Max, %) | C (Max, %) | P (Max, %) | S (Max, %) | Typical Application Orientation |
|---|---|---|---|---|---|---|---|
| CaSi 28/60 | 60 | 28 | 2.0 | 0.8 | 0.04 | 0.05 | General carbon steel refining, ordinary gray iron |
| CaSi 30/60 | 60 | 30 | 1.5 | 0.6 | 0.03 | 0.04 | Standard ladle refining, cored wire raw material |
| CaSi 31/60 | 60 | 31 | 1.2 | 0.5 | 0.03 | 0.03 | Clean steel, pipeline steel, low-sulfur ductile iron |
| High-purity CaSi 32/62 | 62 | 32 | 1.0 | 0.4 | 0.02 | 0.02 | Bearing steel, automotive deep drawing steel, special alloy |
Expert Tip: Higher calcium content improves desulfurization efficiency, but raises raw material cost. Do not blindly select ultra-high Ca grades if your molten metal sulfur requirement is not strict.
Common Size Specifications & Characteristics of CaSi Powder
| Particle Range | Equivalent Mesh | Core Features | Limitations |
|---|---|---|---|
| 0 ~ 0.2 mm | -200 ~ -325 mesh | Ultra-fine, rapid reaction; high activity | Easy oxidation during transportation, high dust risk |
| 0.2 ~ 2 mm | 80 ~ 200 mesh | Balanced reaction speed & anti-oxidation; uniform filling | Standard universal powder size |
| 0 ~ 3 mm | 40 ~ 180 mesh | Low dust, good fluidity for pneumatic injection | Slow dissolution compared with finer fractions |
| Custom narrow-size fraction (0.15–0.5 mm) | 60–150 mesh | Few oversize & ultra-fine particles; stable for wire production | Higher processing cost |
Matching Calcium Silicon Powder with Typical Metallurgical Processes
Ladle Refining Furnace (LF) / RH Vacuum Refining – Powder Pneumatic Injection
Process Characteristics:
CaSi powder is blown into molten steel via carrier gas for calcium treatment. Target: modify alumina inclusions, avoid continuous casting nozzle blockage, reduce sulfide segregation.
Recommended Selection:
Grade: CaSi30/60 or CaSi31/60
size: 0 ~ 3 mm or 0.2 ~ 2 mm
Impurity requirement: Al ≤1.5%
Key Notes: Avoid excessive ultra-fine powder (<0.1mm). Fine particles burn quickly on the slag surface and reduce calcium recovery.
Cored Wire Production (Steel-clad CaSi Wire Filler)
Process Characteristics:
Calcium silicon powder is continuously filled into steel strips. Uneven particle size causes wire breakage, material segregation and unstable feeding performance.
Recommended Selection:
Grade: CaSi30/60 (most popular global specification)
size: Custom narrow fraction 0.15–0.5 mm
Control indicator: Limit oversize >0.8mm and ultra-fine <0.1mm
Impurity: Low carbon version preferred for low-carbon steel production
Gray Iron & Ductile Iron Foundry (Ladle Inoculation)
Process Characteristics:
Used as auxiliary inoculant to eliminate chill tendency, refine graphite structure and improve casting mechanical performance. Often matched with ferrosilicon inoculant.
Recommended Selection:
Ordinary gray cast iron: CaSi28/60, 0–3 mm powder
High-grade ductile iron, pipe castings: CaSi30/60, 0.2–2 mm
Reminder: Do not use ultra-fine powder for late inoculation; premature oxidation weakens inoculation effect.
Briquetting Raw Material (CaSi Briquette Production)
Process Characteristics:
CaSi powder is pressed into briquettes to solve dust pollution and improve feeding convenience.
Recommended Selection:
Grade: Cost-effective CaSi28/60 or CaSi30/60
Particle: Mixed size 0 ~ 3 mm improves briquette strength
Suggestion: Control moisture below 0.3% to prevent briquette cracking
Special Alloy Smelting & Master Alloy Manufacturing
Process Characteristics:
Raw material for Si-Ca-Al, Si-Ca-Ba composite inoculants and deoxidizers for premium alloys.
Recommended Selection:
Grade: High-purity CaSi32/62
Particle: 0 ~ 0.2 mm ultra-fine powder
Strict control of P and S impurities to avoid contaminating final alloys
Common Mistakes When Purchasing Calcium Silicon Powder
Only focusing on Si & Ca content while ignoring size distribution
Many suppliers provide qualified chemical composition but irregular sizing, resulting in 10~25% lower element recovery rate. Always require suppliers to provide size test reports.
Selecting ultra-fine powder for open ladle addition
Ultra-fine CaSi powder rapidly oxidizes when exposed to air, wasting raw materials and increasing slag volume.
Ignoring moisture content
Calcium silicon reacts violently with water. Damp powder causes molten metal splashing hazards. Standard requirement: moisture ≤0.3%.
One specification for all production lines
Cored wire, injection metallurgy and foundry inoculation cannot share the same powder specification. Unified purchasing leads to unstable production.
FAQ
Q1: Is higher calcium grade always better for steel refining?
A: No. Higher Ca grades raise procurement cost. If your target sulfur content is above 0.015%, standard CaSi30/60 can meet requirements. Only low-sulfur clean steel requires CaSi31/60 or higher grades.
Q2: Can calcium silicon powder replace calcium silicon lumps completely?
A: Powder has faster reaction speed, yet it suffers higher oxidation loss in open furnaces. Manual ladle addition usually adopts granules/lumps; automated injection and cored wire must use qualified powder.
