Calcined Doloma (CaO·MgO)
Calcined Doloma, also frequently referred to as Doloma or Burnt Dolomite, is the product obtained by heating (calcining) natural dolomite stone to high temperatures (typically 900°C to 1800°C).5 This thermal decomposition drives off the carbon dioxide (CO2), converting the double carbonate into a mixture of the two corresponding oxides: Lime (CaO) and Magnesia (MgO), which are the refractory phases.
Mineral Phases and Composition
The final refractory product is an aggregate of two separate mineral phases: Periclase (MgO) and Lime (CaO).
| PHASE | CHEMICAL FORMULA | PROPERTY HIGHLIGHT |
| Periclase | MgO (Magnesium Oxide) | High melting point, strong basicity, good resistance to hydration. |
| Lime | CaO (Calcium Oxide) | Extremely high melting point (2572°C), superior ability to scavenge impurities like Sulfur (S) and Phosphorus (P). |
| CLASSIFICATION | MELTING POINT | PRIMARY APPLICATION FOCUS |
| Dead-Burned Doloma | ~2370°C (Eutectic) | Basic refractory bricks and granular furnace fettling materials. |
Key Performance Metrics
| PROPERTY | TYPICAL PERFORMANCE | MECHANISM OF ADVANTAGE |
| Basicity / Slag Resistance | EXCELLENT | High CaO content provides exceptional resistance to highly basic steelmaking slags. |
| Scavenging | SUPERIOR | The free CaO phase is highly effective at absorbing impurities like S and P from molten steel, enabling clean steel production. |
| Refractoriness | VERY HIGH | The MgO–CaO system has a very high eutectic temperature. |
| Hydration Resistance | POOR | Major drawback: The CaO phase reacts easily with atmospheric moisture to form Ca(OH)2, causing cracking and disintegration. |
Advantages and Key Characteristics
Calcined Doloma is a preferred basic refractory where slag composition and steel cleanliness are critical.
- Clean Steel Production: The CaO component makes it invaluable in secondary metallurgy, particularly in ladle and converter linings. The CaO readily reacts with and removes S and P from the molten steel, which is necessary for producing high-quality, ultra-low-carbon steel.
- High Temperature Stability: It maintains its mechanical and chemical properties at the extreme temperatures common in modern steelmaking, such as the basic oxygen furnace (BOF) and argon-oxygen decarburization (AOD) vessels.
- Cost-Effective and Abundant: Dolomite is a globally abundant resource, making doloma a cost-effective alternative to other premium basic refractories like high-purity magnesia-chrome bricks.
Typical Industries and Applications
- Steel Industry:
- Basic Refractory Bricks: Used to line the working zones of BOF and AOD converters, electric arc furnace (EAF) slag lines, and steel teeming ladles.
- Fettling/Patching Material: Used in granular form to repair hearths and maintain slag lines in furnaces.
- Cement Industry: Used to line rotary cement kilns, where it resists the basic clinker.
Technical Guidance and Limitations
The application of doloma is almost entirely governed by its primary limitation:
- Hydration: The high affinity of CaO for moisture requires that doloma refractories be kept dry at all times. They must be packaged in moisture-proof bags, stored in heated environments, and installed quickly. Refractories incorporating doloma often include stabilizers (like magnesia or iron oxide) or are bonded with pitch/tar to temporarily protect the CaO from atmospheric moisture.
- Magnesia-Doloma Refractories (Mag-Dol): To improve hydration resistance and thermal shock performance, doloma is often blended with higher proportions of sintered magnesia (MgO), resulting in a magnesia-doloma refractory, which offers a balance of CaO‘s scavenging ability and MgO‘s stability.
✨ 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. |
