Products

# Clay Castables: A Vital Branch of Unshaped Refractories As an important subcategory of unshaped refractory materials, clay castables have secured an irreplaceable position in high‑temperature industrial applications thanks to their unique performance advantages and wide range of applications. Utilizing soft clay as a binder, clay castables are formulated through precise proportions of refractory aggregates, fine powders, and admixtures, resulting in a casting material that boasts exceptional high‑temperature resistance and outstanding workability. Consequently, they have become the preferred lining material for high‑temperature equipment in industries such as metallurgy, building materials, and chemical engineering. The Material Composition and Classification System of Clay Castables The core components of clay castables include refractory aggregates, fine powders, binders, and admixtures. Refractory aggregates typically consist of high‑alumina bauxite clinker, corundum, mullite, or sillimanite—materials whose particle size distribution directly influences the density and strength of the castable. For example, Grade A bauxite clinker from Yangquan, Shanxi, with its high alumina content and minimal impurities, is an ideal aggregate for producing high‑strength clay castables. Fine powders are often made by grinding premium or first‑grade high‑alumina bauxite clinker, with more than 90% of particles smaller than 0.09 mm to ensure uniformity in the matrix material. Binders, exemplified by soft clay from Guangxi, impart excellent plasticity and bonding properties to the castable; the addition of dispersants such as sodium hexametaphosphate can significantly reduce water demand and enhance material fluidity. Based on performance characteristics and application scenarios, clay castables can be further divided into standard and high‑strength varieties. Standard castables exhibit a room‑temperature compressive strength of 3–6 MPa and are suitable for medium‑ and low‑temperature environments such as steel rolling heating furnaces and soaking furnaces. High‑strength castables, on the other hand, incorporate 20%–30% corundum or mullite aggregates, combined with ultrafine powders and composite admixtures, boosting room‑temperature strength to over 10 MPa and achieving a high‑temperature compressive strength of 8–12 MPa at 1400°C—meeting the stringent requirements of critical components like torpedo cars and desulfurization nozzles. Performance Advantages and Technological Breakthroughs in Clay Castables Compared with traditional cement‑bonded refractory castables, clay castables demonstrate a distinct advantage in mid‑temperature strength. While cementitious materials experience a sharp drop in strength between 800°C and 1200°C due to the decomposition of hydration products, clay‑bonded systems rely on the formation of mullite crystalline phases, which not only prevent strength degradation but actually increase material strength within this temperature range, effectively resisting thermal shock. Experimental data show that clay castables using Yangquan bauxite from Shanxi as aggregate exhibit a flexural strength increase of 15% after heat treatment at 1100°C compared to their room‑temperature strength, whereas cement‑bonded materials suffer a strength reduction of up to 40% during the same period. In terms of high‑temperature volume stability, clay castables optimize aggregate gradation and matrix composition to keep apparent porosity below 18% and linear change within ±0.5%. For instance, formulations incorporating white corundum aggregates and silica sol composites can achieve a post‑sintering shrinkage rate of less than 0.3% at 1500°C—far surpassing the industry standard requirement of ≤1.0%. This superior volume stability ensures the structural integrity of furnace linings even under prolonged high‑temperature service conditions. Optimizing construction performance represents another key focus in the technological development of clay castables. By introducing delayed‑setting accelerators such as sodium tripolyphosphate, the initial flow value of the material can reach over 220 mm, meeting the demands of pump‑based construction while still maintaining a demolding strength above 5 MPa after 24 hours. This “slow setting, fast hardening” characteristic not only extends the construction window but also shortens equipment maintenance cycles. A case study from a steel enterprise shows that when clay castables were used to repair a heating furnace hearth, the furnace firing time was reduced by 3 days compared to conventional materials, and the number of annual maintenance operations dropped from 4 to just 1. Industry Applications and Typical Cases of Clay Castables In the metallurgical industry, clay castables have become a critical material for core equipment such as blast furnaces, converters, and electric furnaces. High‑strength castables are used to fill the gaps between furnace throat steel bricks, capable of withstanding molten iron erosion at 1600°C and boasting a service life of over 5 years; standard castables are widely employed in areas such as heating furnace walls and burner bricks, where their resistance to CO corrosion is 30% higher than that of traditional brickwork. An aluminum company used clay castables to rebuild the melt‑aluminum furnace taphole; at a working temperature of 750°C, the depth of aluminum liquid penetration was reduced from 8 mm to 2 mm, resulting in annual maintenance cost savings of 1.2 million yuan. Applications in the building materials sector are equally extensive. Replacing traditional brickwork with clay castables in the transition zone of cement rotary kilns lowers the kiln shell temperature by 50°C and reduces specific thermal consumption per ton of clinker by 3 kcal/kg. In glass tank walls and ceramic shuttle kilns, the material’s high thermal shock resistance (ΔT ≥ 300°C) effectively minimizes the risk of cracking, increasing equipment utilization by 15%. The chemical industry places even higher demands on material corrosion resistance. Applications of clay castables in petrochemical cracking furnaces and sulfur recovery units demonstrate that their resistance to H₂S and CO₂ corrosion outperforms magnesia bricks, with an annual corrosion rate of less than 0.5 mm in 1200°C acidic environments. In a fertilizer plant renovation project, the converter furnace lining repaired with clay castables retained a strength retention rate of over 85% after two years of continuous operation, as confirmed by sampling and testing. Technological Trends and Future Prospects As high‑temperature industries evolve toward greater efficiency and energy conservation, clay castable technology is undergoing three major trends: First, material performance is being enhanced—through nano‑alumina modification and silicon carbide fiber reinforcement—to enable use temperatures exceeding 1600°C; second, construction is becoming more convenient—with the development of self‑leveling and vibration‑free products tailored to meet the needs of complex, non‑standard geometries; and third, functional integration is advancing—incorporating multiple functions such as anti‑scaling, crack‑resistance, and thermal conductivity regulation—to expand applications in emerging fields like waste incineration furnaces and hazardous waste treatment furnaces. Currently, the industry is focusing on addressing the issue of creep under long‑term high‑temperature service. By introducing high‑temperature phase stabilizers such as zirconia and sialon, coupled with optimized particle size distributions, the creep rate of next‑generation clay castables has been reduced to…

Silicon Carbide Castables I. Main Product Types Standard Grade (SiC-70): SiC content 65–75%, Al₂O₃ 15–25%, bulk density 2.5–2.7 g/cm³; suitable for temperatures up to 1450°C (in cement kiln decomposition furnaces). High-Purity Grade (SiC-90): SiC ≥ 85%, with a nano-SiO₂ coating added; apparent porosity ≤ 15%, capable of withstanding temperatures up to 1600°C (critical components in waste incineration furnaces). Composite Reinforced Grade: SiC–ZrO₂ gradient structure (with 15% ZrO₂ on the surface); thermal shock resistance ≥ 30 cycles (water quench at 1100°C); alkali corrosion resistance improved by 50%. II. Production Processes Low-Temperature Firing Technology: Microwave-Assisted Drying (reducing energy consumption by 40%); Nitrogen‑Protected Sintering at 1450°C (compared to the traditional requirement of 1600°C); Digital Quality Control: Online Thermal Imaging Monitoring (temperature deviation ±5°C); AI Prediction Models (strength deviation ≤ 3%). III. Applications Application Areas & Typical Cases: Key Performance Improvements: – Extended service life of new energy lithium battery sintering kilns to 5 years. – Increased corrosion resistance by +70% for linings in hazardous waste melting furnaces. – Enhanced thermal shock stability of 25 cycles in the transition zone of cement rotary kilns. – Reduced power consumption by 8% on the sidewalls of metallurgical aluminum electrolysis cells. IV. Performance Advantages – Compared with Traditional Materials: Thermal Conductivity: 12 W/(m·K) vs. high-alumina bricks at 1.8 W/(m·K). Wear Resistance: Volume wear ≤ 5 cm³ (ASTM C704). CO Corrosion Resistance: Strength retention ≥ 90% after 1000°C/200 hours. Economic Analysis: Initial Cost: 60% lower than electrofused zirconia–corundum bricks. Maintenance Costs: No major overhauls required for 3 years (compared to the traditional 1.5 years). V. Physicochemical Specifications 1. Basic Performance (SiC-70): – Compressive Strength: ≥ 60 MPa (110°C × 24 h). – High-Temperature Flexural Strength: ≥ 8 MPa (1400°C × 3 h). Thermal Properties: – Coefficient of Thermal Expansion: 4.5 × 10⁻⁶/°C (20–1000°C). – Thermal Shock Resistance: ≥ 20 cycles (from 1100°C to water quench). Chemical Stability: – Acid Slag Resistance: Erosion depth ≤ 1.2 mm/24 h. – Alkali Penetration Resistance: K₂O penetration ≤ 0.8 mm.

Lightweight Insulating Castables I. Core Product Types Perlite-Based Series (ZL-800) Dry Density: 600–800 kg/m³ Aggregate Ratio: 60% Expanded Perlite + 20% Ceramic Proppant Operating Temperature: ≤900℃ Mullite-Based Series (ZL-1200) Lightweight Mullite Aggregate (Porosity ≥55%) Bulk Density: 0.8–1.2 g/cm³ Maximum Service Temperature: 1200℃ Alumina Hollow Sphere Type (ZL-1600) Al₂O₃ ≥90%, hollow sphere particle size 0.2–5 mm Thermal Conductivity: 0.15 W/(m·K) at 800℃ Continuous Service Temperature: 1600℃ II. Production Process Intelligent batching system; aggregate AI pre-mixing (grading accuracy ±1%) Composite binder (aluminate cement + silica fume) Energy‑efficient drying process: microwave–hot air co‑drying (energy consumption reduced by 40%) Moisture content control: ≤5% (110℃ × 8 h) Green additives: organic fibers (to prevent cracking) and nano‑aerogel (thermal conductivity reduced by 30%) III. Applications Application Fields & Use Cases Energy Efficiency: — In the petrochemical industry, thermal insulation lining for cracking furnaces reduces heat loss by 35%. — In new energy battery production, insulation layers in lithium‑ion sintering kilns cut energy consumption by 18%. — In building energy conservation, ultra‑low‑energy buildings achieve exterior wall insulation with a thermal conductivity of ≤0.08. — In aerospace, thermal protection shields for rocket engines withstand temperatures up to 2000℃. IV. Performance Advantages – Comparison with Traditional Materials Weight: Only 1/4 that of fireclay bricks Construction Efficiency: 5–8 times faster (can be cast on-site) Heat Loss: Reduced by 40–60% Economic Analysis — Comprehensive cost: 30% lower than ceramic fiber modules — Maintenance cycle: Extended to 5–8 years V. Physicochemical Specifications (GB/T 2026–QZ) 1. Basic Performance (ZL-1200 Type): — Compressive Strength: ≥3.5 MPa (after drying at 110℃) — Post‑fire Linear Change: ±0.5% (at 1200℃ × 3 h) Thermal Properties: — Thermal Conductivity: — 400℃: 0.12 W/(m·K) — 800℃: 0.18 W/(m·K) — Heat Capacity: 1.1 kJ/(kg·K) at 800℃ Durability Indicators: — Frost Resistance: After 50 freeze‑thaw cycles, strength loss ≤10% — Alkali Resistance: K₂O erosion depth ≤2 mm/100 h

Coal Injection Nozzle Castable I. Product Classification and Characteristics Corundum–Silicon Carbide Type (PMC-80) Composition: Electrofused Corundum (≥85%) + Silicon Carbide (8–12%) Temperature Resistance: 1700°C for long‑term use Thermal Shock Resistance: ≥15 cycles (water quenching at 1100°C) Red Silicate Composite Type (PMH-75) Formulation: Red Silicate (30%) + High‑Alumina Bauxite (50%) Characteristics: Excellent high‑temperature volume stability (linear change ≤0.3%) Nano‑Reinforced Innovation: Incorporates 3–5% nano‑Al₂O₃/ZrO₂ Performance: Improves spalling resistance by 50% II. Production Process Raw Material Pre‑Treatment: – Corundum Aggregate: Plasma Activation (increases specific surface area by 30%) – Nanopowders: Ultrasonic Dispersion (agglomeration rate ≤5%) – Microwave Curing Technology: Curing cycle: 8 hours (compared to the traditional 72 hours) – Early Strength: ≥20 MPa (after 24 hours) III. Application Scenarios Typical Operating Conditions & Service Life: Cement Industry: Front end of kiln head burners – 6–9 months Metallurgical Industry: Blast furnace coal injection lances – 4–6 months Power Industry: Pulverized coal boiler burners – 12–18 months Chemical Industry: Gasifier nozzles – 3–5 months IV. Performance Advantages Compared to Traditional Materials Anti‑Coking Performance: Coke formation reduced by 80% Wear Resistance: Compressive strength ≥80 MPa vs. traditional 50 MPa Economic Benefits & Construction Efficiency: – 3D Printing Shortens Construction Time by 70% – Annual Savings on Refractory Material Costs: 35% V. Physicochemical Specifications 1. Physical Properties: – Bulk Density: ≥2.8 g/cm³ (PMC-80) – Apparent Porosity: ≤16% Mechanical Properties: – Compressive Strength (at 1400°C): ≥60 MPa – Flexural Strength (at room temperature): ≥10 MPa High‑Temperature Characteristics: – Load Softening Point (at 0.2 MPa): ≥1650°C – Thermal Shock Stability (at 1100°C): ≥15 cycles Special Indicators: – CO Erosion Resistance (at 1000°C): Weight gain ≤0.5% – Thermal Conductivity (at 800°C): ≤2.5 W/(m·K)

Acid-Resistant Castables I. Main Product Types Water Glass–Bonded Type Composition: Water glass (13–16%) + Sodium Fluorosilicate (accelerator) Acid Resistance ≥ 96%, Suitable Operating Temperature: 800–1200°C Typical Formulation: 60–75% Acid-Resistant Aggregate + 25–30% Fine Powder Composite Bonded Type Bi‑component System: Aluminum Phosphate + Silica Sol Acid Resistance Enhanced by 40% in Concentrated Sulfuric Acid Environments Workability Extended to 90 Minutes Lightweight Acid-Resistant Type Volumetric Density: 1.0–1.4 g/cm³ Thermal Conductivity: 0.12–0.90 W/(m·K) Used for weight‑reduction applications such as chimney linings II. Modern Production Processes Intelligent Mixing Systems Aggregate AI Sorting (Acid Resistance ≥ 98%) Fine Powder Nanoscale Modification (SiO₂ Particle Size ≤ 100 nm) Low-Temperature Curing Technology Steam Curing at 80–120°C (Reduces Strength Development Time by 50%) Microwave-Assisted Curing (Reduces Energy Consumption by 35%) Eco-Friendly Additives Chrome‑Free Accelerators (Replacing Sodium Fluorosilicate) Organic Fiber Reinforcement (Crack Resistance Increased by a Factor of 3) III. Applications Application Area Target Component Technical Benefits Environmental Protection Desulfurization Tower Lining Acid Resistance Lifespan ≥ 5 Years Chemical Industry Acid Pickling Tank Anti-Corrosion Layer Maintenance Cycle Extended by 300% Power Generation Flue Liner Weight Reduced by 40% Metallurgy Acid Recovery Unit Operating Temperature Increased to 1300°C IV. Performance Advantage Comparison Comparison with Traditional Materials Construction Efficiency: Overall cast-in-place construction is 5 times faster than acid‑resistant brick masonry Anti‑Permeation Performance: Air tightness improved by 60% (for chimney applications) Economic Analysis Total Cost: 70% Lower Than Lead Lining Structures Service Life: 2–3 Times Longer Than Traditional Mortar V. Physicochemical Specifications 1. Basic Performance (Water Glass Type): - Compressive Strength: ≥ 25 MPa (dried at 110°C) - Flexural Strength: ≥ 6 MPa (heat‑treated at 1000°C) Acid Resistance Characteristics: - After Immersion in 98% Sulfuric Acid: Strength Retention Rate ≥ 95% (30 days) - In Hot, Concentrated Hydrochloric Acid Environment: Erosion Depth ≤ 1 mm/year Construction Parameters: - Initial Setting Time: 40–120 minutes (adjustable) - Flowability: ≥ 180 mm (depending on construction method)

Wear‑Resistant Castables I. Main Product Types Standard Type (GJ‑18 Series) Composition: Electrofused corundum aggregate (Al₂O₃ ≥ 90%) Bonding System: Pure calcium aluminate cement + α‑Al₂O₃ fine powder Bulk Density: 3.2 ± 0.1 g/cm³ Service Temperature: ≤1800℃ Composite Reinforced Type (GJ‑18F) Adding 5–8% silicon carbide fine powder increases wear resistance by 50% (as tested per ASTM C704). Thermal Shock Resistance: ≥15 cycles (water quench at 1100℃). Nanomodified Type (2025 New Technology) Incorporating 2–3% nano‑ZrO₂ boosts high‑temperature flexural strength by 80% (≥12 MPa at 1600℃). Construction performance optimized (flowability ≥ 280 mm). II. Modern Production Processes Intelligent batching system with AI‑optimized aggregate gradation (3–1 mm : 1–0.1 mm : <0.1 mm = 4:3:3). Moisture control accuracy within ±0.3%. Active powder processing: Ultrafine powders with a specific surface area ≥ 6000 cm²/g (BET method). Nanoadditives pre‑dispersed using advanced technology. Quality control system featuring online particle size analysis (laser diffraction method). Automated packaging with moisture content monitoring (≤0.5%). III. Applications Application Areas | Service Locations | Technical Benefits New Energy – Lithium‑Ion Battery Materials: Sintering kiln service life extended to 5 years. Environmental Protection – Hazardous Waste Incineration Furnaces: Cyclone ducts exhibit threefold improved wear resistance. Building Materials – Cement Kilns: Third‑air duct maintenance intervals extended by 60%. Metallurgy – Blast Furnaces: Iron tapping capacity exceeds 200,000 tons. IV. Performance Advantages – Compared with Traditional Materials Wear Resistance: 0.5 cm³ (ASTM C704) vs. 3.2 cm³ (high‑alumina castables). Thermal Shock Stability: 25 cycles vs. 8 cycles (water quench at 1100℃). Erosion Resistance: K₂O penetration depth ≤ 1 mm/100 h. Economic Analysis Construction Efficiency: Rapid drying possible (50℃/h). Total Cost: 40–50% lower than prefabricated components. V. Physicochemical Specifications (GB/T 2026‑GJ) 1. Physical Properties: - Bulk Density: 3.15–3.25 g/cm³ (110℃ × 24 h) - Compressive Strength: ≥80 MPa (1100℃ × 3 h) High‑Temperature Performance: - Flexural Strength (1600℃): ≥8 MPa - Linear Change Rate: ±0.3% (1600℃ × 3 h) Special Indicators: - Wear Volume (ASTM C704): ≤0.8 cm³ - Thermal Conductivity (1000℃): 2.8 W/(m·K)

Alkali-Resistant Castables In high‑temperature industrial applications, the corrosive effects of alkaline environments on refractory materials are a critical factor limiting equipment service life and operational efficiency. As a specialized material designed to withstand erosion by alkali metal oxides—such as K₂O and Na₂O—alkali‑resistant castables leverage their unique chemical composition and physical properties to serve as an indispensable protective barrier in industrial kilns, including cement kilns, glass melting furnaces, and metallurgical furnaces. I. Material Composition and Classification Alkali‑resistant castables are centered around aluminosilicate-based materials, achieving alkali resistance through the synergistic interaction of aggregates, binders, and admixtures. The aggregate varieties are diverse: heavy‑weight formulations often utilize calcined bauxite, calcined clay, or waste porcelain materials, while lightweight formulations employ porous materials such as alkali‑resistant ceramsite and expanded perlite. The primary binder is calcium aluminate cement; some formulations also incorporate sodium silicate or silica fume to enhance mid‑temperature strength. The addition of admixtures—including dispersants, water reducers, and ultrafine powders—can significantly reduce cement content (traditional formulations typically contain 25%–30% cement, whereas optimized formulations now reduce this to 5%–15%), while simultaneously improving material density and resistance to permeation. Based on differences in porosity, alkali‑resistant castables are divided into two main categories: lightweight and heavyweight. 1. Lightweight Alkali‑Resistant Castables: With a porosity exceeding 45%, a density ranging from 1.4 to 1.6 g/cm³, and a thermal conductivity as low as 0.4–0.5 W/(m·K), these castables are primarily used as insulation layers in kilns—for example, on the top covers of cement rotary kiln preheaters and in the shell insulation layers. Typical formulations feature Al₂O₃ contents of 30%–55% and SiO₂ contents of 25%–45%. Through reactions between high‑silica components and alkalis, a viscous liquid phase forms, creating an釉‑like protective layer. 2. Heavyweight Alkali‑Resistant Castables: With a porosity below 45%, a density of 2.2–2.4 g/cm³, and compressive strengths reaching 70–80 MPa, these castables are suited for load‑bearing areas that must withstand both mechanical stress and alkali attack—such as cement kiln kiln mouths, coal nozzles, and tertiary air ducts. Low‑cement heavyweight castables, by incorporating silica fume, achieve mid‑temperature (1000–1200℃) firing strengths comparable to their dry‑cured strengths, effectively addressing the issue of mid‑temperature strength degradation commonly found in traditional materials. II. Alkali Resistance Mechanisms and Performance Advantages The core advantage of alkali‑resistant castables lies in their dynamic protective mechanism. When temperatures rise to 1250℃, the SiO₂ within the material reacts with alkali metal oxides: SiO₂ + K₂O → K₂SiO₃ (potassium silicate) The resulting silicates exhibit high viscosity, forming a dense glaze layer on the material’s surface that prevents further penetration of alkaline substances. Experimental data indicate that formulations using electrofused spinel aggregates deliver the best alkali resistance; after incorporating 5%–7% zirconia powder, test specimens subjected to 8 hours of alkali exposure at 1200℃ showed virtually no damage. Compared to conventional refractory castables, alkali‑resistant products offer three major performance breakthroughs: 1. Corrosion Resistance: In cement kiln systems, these castables can effectively withstand the chemical erosion caused by alkali‑containing materials—such as raw meal, clinker, and fly ash—extending service life by a factor of 2–3. 2. Thermal Shock Stability: Lightweight formulations maintain linear shrinkage rates between −0.3% and −0.5%, while heavyweight formulations exhibit mid‑temperature linear shrinkage of ±0.4%, making them well suited to handle the thermal shocks associated with frequent kiln starts and stops. 3. Construction Versatility: Through optimized gradation design, material fluidity is significantly improved; rapid mixing can be achieved using forced mixers, allowing pourable casting within 25 minutes after water addition, with curing times reduced to just 8–24 hours. III. Typical Application Scenarios 1. Cement Industry: In modern dry‑process cement production lines, alkali‑resistant castables are applied to cover key components such as preheaters, decomposition furnaces, and kiln tail gas chambers. For instance, after repairing a kiln mouth lining with low‑cement heavyweight castables on a 5000 t/d production line, annual maintenance frequency dropped from six times to once, while specific energy consumption per ton of clinker decreased by 3.2%. 2. Glass Manufacturing: The regenerator grid of glass melting furnaces is constantly exposed to Na₂O corrosion; after switching to lightweight alkali‑resistant castables, grid life was extended from 18 months to 42 months, and furnace thermal efficiency increased by 8%. 3. Metallurgical Sector: In the flues and settling chambers of copper and nickel smelting furnaces, alkali‑resistant castables can withstand the corrosive attack of alkali metals present in molten slag, extending maintenance intervals to over 12 months. IV. Construction and Curing Guidelines To ensure optimal material performance, construction procedures must strictly adhere to the following guidelines: 1. Raw Material Control: Mixing water must be potable, with a pH range of 6–8; aggregate alkali solubility should be ≤1.0 g/L to avoid introducing reactive impurities. 2. Mixing Process: High‑strength formulations require the use of forced mixers, with mixing times of 5–8 minutes until uniform; for steel fiber‑reinforced formulations, fiber dispersion must be carefully controlled to prevent agglomeration. 3. Pouring and Curing: Coat mold inner walls with machine oil to facilitate demolding, and apply asphalt paint to embedded components for corrosion protection; remove formwork 24 hours after pouring, then cure in an environment with humidity >90% and temperature between 10–30℃ for 3–7 days. 4. Heat Treatment Schedule: Limit the heating rate to ≤50℃/h, hold at 500℃ for 24 hours to drive off crystallization water, and avoid sudden cooling or heating that could lead to cracking. V. Technological Development Trends As industrial kilns evolve toward larger sizes and greater levels of智能化, alkali‑resistant castables are advancing toward higher performance and multifunctionality: 1. Nanotechnology Modification: By incorporating nano‑SiO₂ and nano‑Al₂O₃ particles, material density and resistance to permeation can be further enhanced.

Refractory Spray Coatings I. Main Product Types Lightweight Spray Coatings (LD Series) Density: 0.8–1.8 g/cm³ Operating Temperature: 600–1200°C Key Components: Clay-based materials / Ceramic proppants / Perlite Medium-Weight Spray Coatings (MD Series) Density: 1.8–2.1 g/cm³ Operating Temperature: 1200–1400°C Aggregate: High-alumina bauxite + mullite Heavy-Weight Spray Coatings (HD Series) Density: ≥2.1 g/cm³ Operating Temperature: 1400–1600°C Aggregate: Corundum / Silicon Carbide II. Production Process Raw Material Pre‑Processing & Intelligent Grading System: Aggregate particle size ≤ 5 mm (with 3–5 mm accounting for 30%) Nano Additives: Enhance adhesion to 92% Formula Optimization & Binder System: Low Temperature: Phosphate / Water Glass Medium Temperature: Aluminate Cement High Temperature: Silica Sol + Ultrafine Powder III. Applications Typical Application Scenarios & Technical Benefits: Steelmaking & Metallurgy: Repair of hot blast stove ducts – construction time reduced by 70% Cement Industry: Maintenance of the transition zone in rotary kilns – service life extended to 3 years Power Generation: Wear-resistant lining in CFB boilers – wear rate reduced by 60% Petrochemicals: Repair of the radiant section in cracking furnaces – thermal shock resistance improved by 50% IV. Performance Advantages Compared with Traditional Bricklaying Construction Efficiency: 10 m³/h vs. 2 m³/8h (manual work) Integrity: Seamless joints, with air tightness improved by a factor of three Economic Analysis: Material Utilization Rate: 85–90% (rebound rate ≤ 10%) Total Cost: 40–50% lower than prefabricated components V. Physicochemical Specifications 1. General Performance (HD Series): - Bulk Density: 2.2 ± 0.1 g/cm³ (GB/T 2997–2025) - Compressive Strength: ≥45 MPa (after drying at 110°C) High-Temperature Properties: - Linear Change: ≤1.0% (at 1400°C for 3 hours) - Thermal Conductivity: 1.8 W/(m·K) at 1000°C Construction Parameters: - Initial Setting Time: 15–30 minutes (adjustable) - Adhesion Strength: ≥1.5 MPa (after 24 hours)

Refractory Castables I. Main Product Types and Characteristics Low-Cement Series (LCC): Cement content 3–8%, Al₂O₃ 50–90%; water addition 5–7%; bulk density 2.3–3.0 g/cm³; service temperature: 1400–1800°C. Ultra-Low-Cement Series (ULCC): Cement content 1–3%, with the addition of ultrafine powders (d₅₀ ≤ 1 μm); compressive strength ≥ 80 MPa (after drying at 110°C); slag penetration resistance improved by 40%. Self-Flowing Castable (SCC): Flow value ≥ 260 mm (no vibration required); suitable for constructing complex structures, such as burners. New Nano-Composite Castable: Contains 2–5% nano-Al₂O₃/SiO₂, enhancing thermal shock resistance to 50 cycles (water cooling from 1100°C) and achieving wear resistance meeting ASTM C704 standards. II. Modern Production Processes Intelligent batching system; three-dimensional motion mixing (CV ≤ 0.3%); particle-size gradation optimized using the Dinger–Funk equation; composite bonding technologies: hydration bonding (aluminate cement), coagulation bonding (silica sol + ultrafine powders), and chemical bonding (phosphates); green production innovations, including water-free binders (reducing baking energy consumption by 30%) and a waste-recycling rate of 45%. III. Application Scenarios Typical Applications and Technical Benefits New Energy Lithium-Ion Battery Cathode Sintering Kiln: Service life extended to 5 years. Hydrogen-Energy Electrolyzer Liner: Resistance to hydrogen embrittlement improved by 60%. Environmental Protection Hazardous-Waste Melting Furnace: Corrosion resistance reaches Class A. Aerospace Rocket Engine Liner: Withstands temperatures up to 2000°C under 10 MPa. IV. Performance Comparison Advantages over Traditional Shaped Bricks Construction Efficiency: Increased by 300% (no masonry required). Integrity: No joints, with air-tightness improved by 50%. Ease of Repair: Local patching possible. Economic Analysis Initial Cost: 20–30% lower than shaped bricks made of the same material. Overall Benefits: Maintenance costs reduced by 60%. V. Physicochemical Specifications (GB/T 2026–NCC) 1. Basic Properties (LCC–70): – Bulk density: 2.65 ± 0.05 g/cm³ (GB/T 2997). – Compressive strength: ≥ 60 MPa after drying at 110°C for 24 hours. High-Temperature Characteristics: – Flexural strength (1400°C for 3 hours): ≥ 12 MPa. – Linear change after re-firing (1500°C): ± 0.3%. Special Indicators: – Resistance to alkali erosion (K₂CO₃ at 1300°C): Penetration ≤ 1.0 mm. – Thermal conductivity (800°C): 1.2 W/(m·K).

Mullite Castable I. Main Product Types Standard Grade (ML-70) Composition: 70–75% Al₂O₃, 22–25% SiO₂ Aggregate: Porous Mullite (particle size 0–12 mm) Service Temperature: ≤1600℃ Composite Reinforced Grade (MLS-80) Adds 5–8% silicon carbide fine powder High‑temperature flexural strength increases by 40% Thermal shock resistance ≥25 cycles (water quench at 1100℃) Lightweight and Energy‑Efficient Grade Closed porosity ≥30% Thermal conductivity 0.8 W/(m·K) Volumetric density 1.6–1.8 g/cm³ II. Modern Production Processes Intelligent Proportioning System Utilizes AI algorithms to optimize gradation (coarse:medium:fine = 45:30:25) Nano-silica sol binder replaces 30% of cement Low‑Temperature Activation Technology Introduces andalusite fine powder (which transforms into mullite at high temperatures) Firing temperature reduced to 1350℃ (energy savings of 25%) 3D Printing Molding Allows for customization of complex precast components Dimensional accuracy up to ±0.5 mm III. Application Fields Application Industry Typical Applications Performance Benefits Petrochemicals Lining for Catalytic Cracking Units Service life extended to 5 years Electric Power Circulating Fluidized Bed Boilers Wear resistance increased by a factor of 3 Metallurgy Permanent Lining for Steel Ladles Weight reduced by 30% New Energy Sintering Kilns for Lithium Batteries Energy consumption reduced by 18% IV. Performance Advantages Comparison with Traditional Materials Thermal Shock Resistance: 20 cycles vs. 8 cycles for high‑alumina bricks Construction Efficiency: On-site pouring speed increased by 50% Maintenance Costs: Local repairs take 70% less time Technological Breakthroughs Self‑Healing Technology: Microcracks self‑heal at high temperatures Intelligent Monitoring: Embedded fiber optic sensors enable real‑time monitoring V. Physicochemical Specifications (GB/T 2026–ML) 1. Basic Parameters: - Volumetric Density: 2.3–2.5 g/cm³ (Standard Grade) - Strength After Drying at 110℃: ≥50 MPa High‑Temperature Performance: - Linear Change After Firing at 1600℃: ±0.3% - Thermal Conductivity at 1400℃: 1.2 W/(m·K) Special Indicators: - Alkali Resistance: K₂O erosion ≤1.0 mm/100 h - CO Erosion Resistance: Strength loss ≤15%

Magnesium-Chrome Castable I. Main Product Types Standard Grade (MGC-70) Composition: 60–65% MgO, 8–12% Cr₂O₃ Volumetric Density: 2.9–3.1 g/cm³ Operating Temperature: ≤1650℃ High-Chromium Grade (MGC-85) Chromium oxide (Cr₂O₃) content: 15–20%, with the addition of zirconia fine powder Resistance to slag erosion improved by 40% Thermal shock stability ≥15 cycles (water quench at 1100℃) Nano‑Modified Grade (2025 New Technology) Nano‑sized MgO–Cr₂O₃ composite powder (particle size ≤100 nm) Medium‑temperature strength increased by 50% Construction performance optimized (self‑leveling value ≥280 mm) II. Production Process Pre‑Processing System for Raw Materials Electrofused magnesia (MgO ≥97%) is co‑ground with chromite ore (Cr₂O₃ ≥35%) Particle size control: D50 = 15–20 μm Composite Bonding System Phosphate + Silica Fume Dual Bonding System Water reducer dosage: 0.1–0.3% (polycarboxylate-based) Intelligent Mixing Technology Two‑axis forced mixer (rotational speed: 45 rpm) Water addition control: 5.5–6.5% (AI‑driven dynamic adjustment) III. Application Scenarios Application Field Target Area Performance Benefits Copper Smelting Flash Furnace Reaction Tower Service life extended to 18 months Cement Industry Rotary Kiln Transition Zone Scaling resistance improved by 60% Hazardous Waste Treatment Furnace Slag Line Area Corrosion resistance increased by a factor of three Iron and Steel Metallurgy RH Refining Furnace Immersion Tube Thermal shock stability reaches 25 cycles IV. Performance Advantages Compared Compared with Traditional Brick Lining Overall Integrity: Seamless construction with excellent impermeability Ease of Maintenance: Local repairs can be carried out without shutting down the furnace Lifespan: 30–50% longer than masonry structures V. Physicochemical Specifications (GB/T 2026–MGC) 1. Basic Performance (MGC-70): - Compressive Strength: ≥50 MPa (110℃ × 24 h) - Flexural Strength: ≥8 MPa (1400℃ × 3 h) High‑Temperature Characteristics: - Linear Change Rate: ±0.5% (1600℃ × 3 h) - Thermal Conductivity: 2.8 W/(m·K) (1000℃) Special Indicators: - Resistance to Copper Slag Erosion: ≤2 mm penetration/72 h (1300℃) - Setting Time: Initial setting ≥60 min, final setting ≤6 h

Phosphate Castables Phosphate castables are a class of heat‑hardening, unshaped refractory materials formulated by mixing phosphate or phosphate‑solution binders with refractory aggregates, fine powders, and admixtures. Thanks to their outstanding high‑temperature performance, wear resistance, and thermal shock resistance, phosphate castables occupy a crucial position in high‑temperature industrial furnaces across sectors such as metallurgy, building materials, and chemical engineering. This article will analyze phosphate castables from four perspectives: material composition, performance characteristics, application scenarios, and construction techniques. Material Composition and Classification The core raw materials of phosphate castables include binders, refractory aggregates, fine powders, and admixtures. Binders typically consist of phosphoric acid, aluminum dihydrogen phosphate, or polyphosphates; these react slowly with aggregates at room temperature, necessitating the addition of admixtures to regulate the hardening rate. Common hardening agents include magnesium oxide, ammonium fluoride, and activated aluminum hydroxide. Among these, magnesium oxide is widely used due to its pronounced setting‑accelerating effect—but it’s important to note that the magnesium phosphate formed has relatively poor heat resistance, which may compromise high‑temperature strength. The selection of refractory aggregates directly influences material performance. High‑alumina aggregates (such as calcined bauxite) are ideal for high‑temperature environments; corundum aggregates enhance wear resistance; silicon carbide aggregates deliver excellent performance under reducing atmospheres; and magnesia aggregates must be paired with sodium polyphosphate to prevent rapid setting. Fine powders are often high‑alumina powder, spinel‑magnesia powder, or silica fume, used to fill pores and strengthen bonding. In addition, to inhibit reactions between iron impurities and phosphoric acid, inhibitors such as oxalic acid and tartaric acid are frequently added to extend the material’s shelf life. Performance Characteristics and Advantages The core advantage of phosphate castables lies in their heat‑hardening properties. Unlike cement‑bonded castables, phosphate systems gradually harden through chemical bonding at room temperature, allowing direct firing without the need for curing—significantly shortening the construction cycle. Their high‑temperature performance is equally impressive: 1. Stable hot‑state strength: Below 1000°C, the strength of phosphate castables increases with rising temperature; at 1000°C, their hot‑state flexural strength can reach 1.5 times their room‑temperature strength—far superior to high‑alumina cement castables. 2. Excellent thermal shock resistance: The material is less prone to spalling under temperature gradients, making it well suited for industrial furnaces that experience frequent start‑ups and shutdowns. 3. Strong wear resistance: Phosphate castables based on high‑alumina or silicon carbide exhibit better wear resistance than ordinary refractory bricks, making them ideal for areas subject to severe erosion. 4. Good corrosion resistance: The phosphate system contains no alkali metals, offering strong resistance to chemical attack from slag and molten metals. However, phosphate castables also have certain limitations. Their high‑temperature strength (above 1400°C) tends to decline as the binder decomposes, and the material is relatively expensive. Moreover, construction is sensitive to ambient humidity—moisture absorption must be avoided. Typical Application Scenarios The applications of phosphate castables span multiple high‑temperature industrial fields: 1. Metallurgy: In steelmaking furnaces, coke ovens, and iron tapping channels, phosphate castables can withstand slag erosion and mechanical wear. For example, a steel plant used corundum–phosphate castables to repair the iron tapping raceway of a blast furnace, extending service life by 40% compared to traditional materials. 2. Building Materials: Phosphate castables are commonly used in transition zones and coolers of cement rotary kilns, where their thermal shock resistance helps reduce cracking in brickwork caused by temperature fluctuations. 3. Chemical Industry: In the corrosive environments of sulfuric acid and phosphoric acid production units, phosphate castables’ chemical stability makes them a critical lining material. 4. Power Industry: In the upper furnace section of circulating fluidized bed boilers and in cyclone separators, phosphate‑bonded wear‑resistant plastics are employed, with service lives exceeding five years—far surpassing those of conventional castables. In addition, phosphate castables are widely used for rapid repairs in industrial furnaces. Their ability to avoid lengthy curing periods makes them the preferred material for emergency repairs—for instance, when localized damage occurs on the roof of a heating furnace, phosphate castables can be directly poured and quickly baked to restore production. Construction Techniques and Precautions The construction of phosphate castables requires strict adherence to established procedures: 1. Mixing and Blending: Weigh dry ingredients according to specified proportions, add 50%–60% of the phosphate solution for the initial mix, and allow the mixture to “set” for 24–48 hours to neutralize iron impurity reactions. Before construction, add a setting accelerator—such as high‑alumina cement—as well as the remaining phosphate during the second mixing, keeping the mixing time within 3–4 minutes. 2. Formwork and Pouring: Use steel or wooden forms to maintain the desired shape; the formwork contact surfaces should be lined with kraft paper or plastic sheeting to facilitate demolding. During pouring, use a vibrator to compact the material until slurry appears on the surface, avoiding over‑vibration that could lead to delamination. 3. Curing Schedule: The curing curve must be tailored to the material’s thickness. For example, a 300mm‑thick furnace lining should be gradually heated to 350°C to drive off free water and crystalline water, then follow the standard firing curve for refractory bricks to complete sintering. Improper curing can result in cracking or spalling. Controlling the construction environment is equally critical. Phosphate castables are highly hygroscopic; curing temperatures should be maintained between 20°C and 50°C, with relative humidity below 60%. When working in humid regions or during the rainy season, rain‑proof measures must be implemented, and single batch sizes should be reduced to prevent premature moisture absorption and subsequent failure before the material fully hardens. Conclusion With their unique heat‑hardening properties, high‑temperature stability, and wear resistance, phosphate castables have become an indispensable key material in high‑temperature industrial applications. From furnace linings in metallurgy to inner linings in chemical equipment, their application scope continues to expand—and ongoing optimization of construction techniques further enhances material performance. Looking ahead, as demand grows for lighter, longer‑lasting refractory materials, phosphate castables are poised to demonstrate their value in even more extreme operating conditions through formula improvements and process innovations.