High-Strength Alkali-Proof Castable
Main Chemical Compositions & Categories
This castable utilizes refractory aggregates (often High Purity Al2O3 or Calcined Fireclay) and is characterized by a bonding system and matrix additives that specifically limit the reaction sites for alkali compounds and increase the density of the product. SiC or Zircon may be added to increase chemical stability.
| COMPONENT | KEY ADDITIVE | FUNCTION | PRIMARY ADVANTAGE |
| Matrix | High Purity Alumina/Mullite | Refractoriness and Structural Base | High hot strength and stability |
| Alkali Inhibitors | SiC, ZrO2, Low-Flux Al2O3 | Chemical Barrier/Inertness | CRITICAL: Prevents alkali penetration and destructive volume change |
| PERFORMANCE REQUIREMENT | CHEMICAL STRATEGY |
| Alkali Resistance | Minimize Al2O3 and SiO2 content in the matrix that forms low-melting alkali-aluminosilicates. |
| High Strength | Formulated as a Low Cement Castable (LCC) or Ultra Low Cement Castable (ULCC) to maintain structural load-bearing capacity. |
Key Properties and Performance
| PROPERTY | TYPICAL PERFORMANCE | MECHANISM OF ADVANTAGE |
| Alkali Resistance | EXCELLENT | Dense structure and inert matrix prevent destructive alkali burst (volume expansion) and chemical melt. |
| Cold Crushing Strength (CCS) | VERY HIGH | LCC/ULCC formulation ensures strong bond development, resisting structural failure. |
| Permeability | VERY LOW | Minimized pore volume physically inhibits the infiltration of gaseous or liquid alkali. |
| Abrasion Resistance | VERY GOOD | Dense matrix and hard aggregates resist mechanical wear alongside chemical attack. |
Advantages and Key Characteristics
Alkali-Proof Castables are essential for maximizing the campaign life of linings in processes where volatile alkali compounds (released from fuel or raw materials) condense and react with the refractory lining, causing rapid and destructive failure.
- Prevents Alkali Burst: When alkali vapors (like K2O) react with the refractory’s Al2O3 and SiO2, they form low-density, high-volume compounds (e.g., Kalsilite). This causes a massive, destructive volume expansion (alkali burst) that destroys the lining. Alkali-proof formulations use additives and high density to disrupt this chemical reaction pathway.
- High Structural Integrity: Being a high-strength formulation (often LCC/ULCC), it maintains excellent hot strength and resistance to creep, ensuring the lining does not collapse under load or thermal cycling.
- Reduces Melt Formation: By minimizing the amount of free silica and other reactive components, the formation of low-melting alkali-aluminosilicate liquid phases, which lead to premature wear and drip-down, is significantly delayed.
- Monolithic Protection: Installation by casting or gunning creates a seamless lining, eliminating the joints that are the most vulnerable points for alkali vapor penetration in brick linings.
Typical Industries and Applications
This castable is primarily used in industries processing alkali-rich raw materials or using specific types of fuel:
- Cement & Lime Industry: Pre-heater stages, riser ducts, and cyclones, where volatile Na2O and K2O condense and attack the lining.
- Ferrous Industry (Steel): Blast Furnace stack, dome, and cooling stave refractory lining, where alkali attack from the descending coke burden is severe.
- Waste Incineration: Linings in zones where alkali oxides from ash or waste are highly concentrated.
Furnace Areas and Service Zones
They are specified for structural and chemical-wear zones:
- PRE-HEATER CYCLONES & DUCTS (CEMENT): The zones where the alkali salts first condense in the 800°C to 1100°C.
- BLAST FURNACE STACK: Used to resist alkali vapor ingress and attack.
- GENERAL ALKALI CONDENSATION ZONES: Any area downstream of high-temperature alkali vaporization.
Key Data Sheet Properties to Consider
Selection criteria focus heavily on chemical and structural stability:
- Alkali Resistance Test: CRITICAL VALUE. Must demonstrate low Permanent Linear Change (PLC) after exposure to a standardized alkali atmosphere test (e.g., K2CO3 at 1000°C). A low expansion (< 1%) is desired.
- Cold Crushing Strength (CCS): Should be very high (> 80 MPa) after firing) to confirm load-bearing capacity.
- Bulk Density (BD) and Apparent Porosity (AP): High BD and very low AP (e.g., < 15%) are essential to limit alkali infiltration.
- Binder Type: Confirm it is an LCC/ULCC to maintain hot strength alongside chemical resistance.
Technical Guidance: For applications involving extremely high alkali attack, the addition of SiC to the formulation is highly beneficial, as it forms a protective layer and resists attack better than many pure Al2O3 phases. Proper dry-out and heat-up schedules are essential for these dense, low-permeability castables.
✨ Customization Services
We offer product customization services, allowing you to tailor the appearance, dimensions, or specific markings of items like refractory shapes or bricks. This includes options for incorporating specific geometric requirements to ensure seamless integration into your process systems.
🔬 Sampling for Testing & Validation
Free product samples are available for thorough testing and validation. This allows you to confirm the quality, compatibility, and performance of our materials—such as specific bricks, castables, or raw materials—before committing to a full order.
💡 Expertise in Refractory Solutions
Leverage our deep expertise to receive detailed, application-specific refractory solutions. We move beyond just selling products by providing comprehensive plans that encompass material selection, installation guidance, and performance optimization to maximize the lifespan and efficiency of your high-temperature processes.
Rabatec products are exclusively manufactured in facilities that have achieved rigorous ISO certifications across Quality (ISO 9001), Environmental Management, and Occupational Health & Safety. This commitment ensures every product, from refractory bricks to specialized equipment, meets the highest global benchmarks for performance, sustainability, and workplace safety.
📦 Logistics Excellence: Shipping, Packaging, and Marking
Minimizing Risk: We manage all logistics to minimize handling touchpoints and transit shock. Our carriers are pre-vetted for their experience in transporting heavy, fragile, and sensitive industrial materials.
Traceability: Every shipment includes comprehensive documentation and tracking information, providing end-to-end visibility and ensuring precise delivery coordination for your site.
Protection is Paramount: Our packaging strictly follows industry standards to prevent damage, corner chipping, and moisture absorption—especially critical for materials like Basic Refractory Bricks and Refractory Mortars & Mixes.
Robust Palletization: Products are secured on fumigated, high-strength export pallets (e.g., 1100x950mm or similar sturdy dimensions) using heavy-duty strapping and durable protective wrapping (polyethylene sheeting, cardboard, etc.) to withstand long-distance travel and multiple loadings.
Moisture Control: Sensitive materials are protected with appropriate sealing and, where necessary, desiccants or moisture-vapor proof enclosures to maintain the product's integrity until installation.
Clear Identification: All outer packaging is clearly marked on multiple sides with large, legible text for immediate identification and safe handling.
Full Traceability: Markings include all essential data points: Product Name, Quality Grade, Batch Number, Quantity, Net/Gross Weight, Order Number, and the Final Destination/Construction Area. This ensures every pallet can be accounted for and correctly staged upon arrival.
Safety & Compliance: We adhere to all regulatory requirements for marking, labeling, and placarding—especially for any items classified as Dangerous Goods—to ensure full compliance with international and domestic transport regulations.
❓ Frequently Asked Questions (FAQ)
Question | Elaborated Answer |
Q: What is the Refractoriness Under Load (RUL) of your refractories? | A: Refractoriness Under Load (RUL) is a critical property that defines the maximum temperature our materials can withstand while under compressive stress before deforming (softening). Since we offer a wide range of materials—from Alumina-Silicate Bricks to high-performance Silicon Carbide Bricks—the RUL varies significantly. For specific product data, please refer to the product data sheet or submit a quote request for the material you are interested in. |
Q: Where are the Rabatec refractories and materials produced? | A: Our products are primarily sourced from specialized manufacturing plants in China. Crucially, these facilities have all undergone rigorous audits and achieved comprehensive ISO certifications (Quality, Environment, and Safety), ensuring that production adheres to the highest global standards for consistency and performance. |
Q: What refractory materials does the company offer? | A: We supply a comprehensive portfolio of advanced refractory solutions, including: Shaped Products: Alumina & Silica Bricks, Basic & Specialized Bricks (e.g., Magnesia), SiC & Structural Ceramics, and Precast Shapes. Monolithic Products: Refractory Castables, Mixes & Mortars. Insulation: Insulation Fibre and High-Performance Insulation Products. |
Q: How should I choose the appropriate refractory material for my application? | A: Selecting the correct refractory is paramount to process efficiency. The choice depends on three key factors: 1. Operating Environment: Maximum process temperature and thermal cycling (shock). 2. Chemical Attack: Type of slag, molten metal, or corrosive gas being handled (acidic, neutral, or basic). 3. Mechanical Stress: Abrasion, erosion, and static load requirements. We recommend utilizing our detailed refractory solutions service to consult with our engineers for an optimized, application-specific recommendation. |
Q: Which monolithic material should I choose when patching an existing lining? | A: For patching and minor repairs, the ideal monolithic material depends on the parent lining material, the patching depth, and the need for a rapid return to service. Common choices include: Refractory Mortars & Mixes (for minor joints/surfaces) or Plastic Refractories (for areas requiring physical compaction). Always choose a patch material chemically compatible with the existing lining to ensure proper bonding and service life. |
Q: Can I receive product samples before placing a major order? | A: Yes. We gladly provide product samples for your internal testing and validation purposes. This ensures you can confirm the quality, composition, and fit of the material—such as our Refractory Castables or Alumina-Silicate Bricks—in your specific operational environment before committing to a bulk purchase. |
Q: Do you provide certifications to verify material quality? | A: Absolutely. We provide product-related inspection certificates and quality assurance documentation upon request. This verifies that your order has passed all internal quality control checks and meets the required material specifications and industry standards. |
Q: What measures are taken for product protection during transport? | A: We ensure quick, reliable transport by using robust, industrial packaging that strictly follows industry standards. This includes high-strength palletization, heavy-duty strapping, and weather-resistant wrapping to protect fragile items like bricks and mixes from corner chipping, mechanical damage, and moisture during transit. |
