News detail
Lightweight Insulating Castable – High-Energy-Saving Monolithic Refractory for Furnace Back-Up Lining
1. Product Introduction
Lightweight insulating castable is a professional low-density unshaped refractory material specially developed for thermal insulation and energy-saving layers of all kinds of high-temperature industrial furnaces. It adopts hollow alumina bubbles, expanded perlite, lightweight mullite and other porous lightweight aggregates as core raw materials, matched with high-purity fine powder and low-temperature fast-setting composite binder. After precise batching, mixing, casting and baking, it forms a microporous integrated lining with closed internal pores, which fundamentally blocks heat conduction and greatly cuts surface heat loss of furnace shells.
Different from dense working castables that focus on anti-slag erosion, this insulating castable is designed for back-up permanent insulation layers instead of direct flame contact. Its unique porous microstructure locks static air inside the matrix, forming an effective thermal barrier between the furnace working lining and steel shell. It effectively stabilizes internal furnace temperature, avoids excessive temperature rise of external equipment, and reduces safety risks such as scalding and pipeline aging.
Classified by bulk density and maximum service temperature, our series covers ultra-light grade (0.4–0.8 g/cm³, service temp 1100–1200℃), medium-light grade (1.0–1.3 g/cm³, service temp 1250–1300℃) and high-strength lightweight grade (1.5–1.8 g/cm³, service temp up to 1350℃). Customized particle gradation and alumina content formulas are available to match different furnace operating environments.
2. Core Technical Advantages
Ultra-Low Thermal Conductivity & Outstanding Energy Saving
Closed micropore structure controls thermal conductivity within 0.15–0.32 W/(m·K) under 350℃ working temperature, far lower than dense refractory castables. Actual furnace renovation data proves that matching this lightweight insulating castable as back lining can reduce heat dissipation loss by 30%–45%, lower fuel and electricity consumption significantly, and shorten the heating-up time of intermittent kilns. For long-running continuous furnaces, it brings stable long-term energy-saving benefits and cuts comprehensive production costs.
Low Bulk Density & Light Furnace Load
The bulk density ranges from 0.4 to 1.8 g/cm³, only 1/3 to 1/2 of conventional dense castables. It greatly reduces the overall dead weight of furnace linings, lowers bearing pressure on steel frame structures, and saves steel consumption during furnace design and reconstruction. Meanwhile, lightweight raw materials cut transportation costs and labor intensity during on-site construction.
Balanced Mechanical Strength & Stable Volume Stability
Though featuring low density, the product retains reliable cold and hot compressive strength after complete baking. Cold crushing strength after 110℃ drying reaches 2–15 MPa, with load softening performance meeting long-term high-temperature working standards. The permanent linear change after high-temperature firing is controlled within ±0.5%, no shrinkage crack or gap expansion occurs under repeated heating and cooling cycles, maintaining the integrity and tightness of the insulation layer for years.
Excellent Thermal Shock Resistance & Construction Flexibility
Optimized matrix formula endows the castable with superior thermal shock resistance. It will not peel or crack under frequent temperature fluctuation impact during furnace startup and shutdown. As a monolithic refractory, it supports pouring, vibration casting and gunning construction, adapting to complex irregular kiln structures such as furnace arches, flues, furnace walls and pipeline linings. Long operable time after mixing avoids construction waste caused by premature coagulation, and the baking curve is mild without complicated segmented temperature control.
Inert Chemical Property & Wide Compatibility
As neutral to weak acidic refractory, it rarely reacts with working lining bricks, flue gas and high-temperature mediums. Low impurity content prevents alkali mineral phase generation, and no chemical pollution will occur to molten glass, ceramic blanks and other products. It can be matched with silica bricks, high-alumina bricks, mullite refractories and various dense castables without abnormal chemical erosion at the contact interface.
3. Main Application Fields
Glass Industry Kilns
Widely used for back insulation layers of float glass furnaces, bottle glass kilns and art glass melting furnaces, including furnace crown, side wall regenerator and flue lining. It avoids temperature fluctuation of molten glass caused by furnace wall heat leakage and ensures stable quality of finished glass products.
Metallurgical Heating & Heat Treatment Furnaces
Suitable for heating furnaces, soaking pits, annealing furnaces and intermediate ladle permanent layers in steel plants and foundries. It stabilizes furnace temperature field and reduces energy loss during billet heating and heat preservation processes.
Petrochemical & Power Thermal Equipment
Applied as thermal insulation lining for cracking furnaces, reformers, industrial boilers, high-temperature flues and waste heat recovery pipelines. It effectively lowers shell surface temperature and protects external steel structures and auxiliary equipment.
Ceramic Tunnel Kilns & Coke Ovens
Used for back-up insulation of ceramic firing tunnel kilns and coke oven regenerators. The lightweight characteristic reduces kiln car load, speeds up kiln temperature rise and improves production efficiency of firing lines.
Other Industrial High-Temperature Kilns
Matching incinerators, small melting furnaces and laboratory high-temperature furnaces as thermal insulation backing materials, applicable to building materials, non-ferrous metal and machinery manufacturing industries.
4. Production & Quality Assurance
Our lightweight insulating castable is produced on automated batching and mixing production lines. Raw hollow ball aggregates and mineral powder go through multi-stage impurity removal and particle screening to strictly control flux content. Every batch of finished products undergoes full laboratory testing before delivery, covering chemical composition, bulk density, apparent porosity, cold crushing strength, thermal conductivity, permanent linear change and thermal shock resistance. Complete inspection reports and technical data sheets are provided together with goods.
We support customized sizes, formulas and physical indexes according to customer furnace drawings and working conditions, and provide free samples for performance testing. Our professional refractory technical team offers one-stop services including construction scheme guidance, baking curve formulation and after-sales lining maintenance consultation for global industrial partners.
5. Why Choose Our Lightweight Insulating Castable
- Graded porous aggregate design, ultra-low thermal conductivity and remarkable energy-saving effect
- Multiple density & temperature grades to cover full working temperature range from 1100℃ to 1350℃
- Balanced lightweight property and mechanical strength, no lining collapse or cracking during long service
- Flexible construction methods, simple baking operation, short on-site construction cycle
- Low impurity inert formula, compatible with all mainstream acidic and neutral working refractories
- Stable batch quality, complete inspection system and traceable production records
- Professional customized technical support, free samples and targeted cost-effective quotation
- Large factory inventory, fast delivery cycle and stable long-term supply capacity
6. Closing Remarks
Against the backdrop of rising global energy costs and stricter carbon emission standards, energy-saving lightweight insulation refractories have become standard configuration for new furnace construction and old furnace renovation. If you are seeking reliable low-heat-loss back lining materials for your high-temperature kiln projects, welcome to contact us to share your furnace working temperature, lining thickness and equipment parameters, and we will provide matched lightweight insulating castable solutions to lower your long-term operating expenses.
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