Technical article
Steel grit vs. aluminum oxide: comparison for CA blasting equipment
Steel grit vs. aluminum oxide: comparison for compressed-air blasting equipment
In compressed-air blasting processes — blast rooms, tanks, ship holds — equipment works equally with different types of abrasives, allowing selection of the most suitable one for each job. This comparison analyzes the performance and operating cost of angular steel grit against aluminum oxide. Scope note: centrifugal blast wheel equipment cannot use aluminum oxide or sand; this comparison applies exclusively to compressed-air blasting equipment.
The two abrasives: main characteristics
Aluminum oxide (alumina)
Aluminum oxide (Al₂O₃) is a synthetic crystalline substance produced from bauxite. Two types are used for abrasive blasting according to purity level: brown aluminum oxide (minimum 95 % Al₂O₃) and white aluminum oxide (minimum 99 % Al₂O₃). Its high-hardness, sharp-edged particles make it a very aggressive abrasive. It can be recycled 10 to 40 times depending on use and process conditions.
Angular steel grit
Steel grit is obtained by melting steel with controlled chemical compositions. The primary spherical particles are split to generate angular grit, which presents edges and points that dig into and drag across the surface when projected. It does not contaminate the work surface. It is highly recyclable: it can be projected 700 to 5,000 times depending on abrasive diameter, type and hardness. It does not absorb moisture — no pre-drying required — and its uniform particle size produces even results.
Equipment behavior: wear and dust
With equivalent projection equipment and operator protection, aluminum oxide is more abrasive than steel grit, generating greater wear on the abrasive transport line, hoses, couplings and nozzle. It also produces more dust, requiring higher-capacity extraction and filtering systems. Collectors are the most costly part of the installation and filter element maintenance is also higher.
Regarding spent abrasive management: steel grit requires a recovery and cleaning system to reuse it efficiently; aluminum oxide requires a collection and final disposal system.
Performance comparison
The following table compares both abrasives descaling grade B steel plate to Sa 2½ blasting quality, using a 10 mm Venturi nozzle:
| Steel grit | Al. oxide brown | Al. oxide white | |
|---|---|---|---|
| Particle size (mm) | 0,3 - 0,8 | 0,2 - 0,5 | 0,2–1,5 |
| Bulk density (g/cm³) | 3,5 | 1,6 | 2,0 |
| Flow rate (kg/h/nozzle) | 1000 | 460 | 570 |
| Cleaning output (m²/h/nozzle) | 20 | 20 | 18 |
| Abrasive consumption (kg/m²) | 5 | 25 | 30 |
| Dust generation | Baja | Elevada | Elevada |
Note: comparison carried out descaling grade B steel plate to Sa 2½ quality, 10 mm Venturi nozzle.
The most significant figure: at equal cleaning output (around 20 m²/h), steel grit consumes 5 kg/m² against 25–30 kg/m² for aluminum oxide — 5 to 6 times less abrasive per clean square metre.
When aluminum oxide is the right choice
Aluminum oxide is the correct option when the material cannot tolerate contamination with steel particles: aluminum surfaces, stainless steel or certain high-purity coatings where the presence of iron would cause quality or adhesion problems. For those applications, its higher operating cost is justified by the result.
Conclusion: what suits most applications
Compared with aluminum oxide, steel grit used with the right equipment and conditions offers:
• 5 to 6 times lower abrasive consumption per clean m².
• Less dust generation → better visibility, better working conditions for the operator and lower health risk.
• Lower initial investment in dust collection systems.
• Less equipment wear (nozzles, hoses, couplings) and lower maintenance costs.
• Around 80 % reduction in waste treatment cost.