Rock wool, also known as mineral wool insulation, is produced by melting natural basalt rock and converting the molten material into fine fibers. These fibers are then bonded and cured to form insulation boards, blankets, or pipe sections widely used in construction, industrial insulation, and fire-resistant systems.
Modern rock wool production lines integrate melting technology, fiberizing equipment, forming systems, and automated curing processes into a continuous manufacturing system. Understanding the technical stages of this process is essential for manufacturers planning to establish a rock wool factory or upgrade an existing production line.
This article explains the typical rock wool manufacturing process used in modern industrial plants and highlights the key technical parameters that influence product quality and production efficiency.
Rock wool is primarily produced from natural volcanic rock combined with selected mineral additives.
Typical raw material composition includes:
| Material | Percentage |
|---|---|
| Basalt | 60–80% |
| Dolomite / Limestone | 10–20% |
| Recycled slag | 5–15% |
| Coke (fuel for cupola furnace) | 5–10% |
Basalt provides the main silicate structure required for fiber formation, while limestone and dolomite adjust the melting characteristics and viscosity of the molten material.
The chemical composition typically contains:
SiO₂: 38–45%
Al₂O₃: 12–18%
CaO + MgO: 20–30%
Fe₂O₃: 5–10%
These proportions are critical because the viscosity of molten rock must remain within a narrow range during fiberization.
Before entering the furnace, raw materials are crushed and screened to achieve uniform particle size.
Typical particle size range:
10 – 50 mm
A weighing and batching system ensures accurate proportioning of each component.
Modern batching systems use:
automatic belt weighers
PLC-controlled feeding systems
storage silos for different raw materials
Accurate batching is important because small variations in composition can affect fiber quality and melting efficiency.
The melting stage is the most energy-intensive part of the rock wool production process.
Two main furnace types are commonly used:
Cupola furnaces remain widely used due to their high productivity and relatively simple structure.
Typical operating parameters:
Furnace temperature: 1450 – 1550°C
Melting capacity: 6 – 30 tons per hour
Coke consumption: 8 – 12% of raw material weight
Furnace diameter: 1.8 – 3.5 meters
Raw materials are charged from the top of the furnace, while molten rock flows continuously from the bottom tapping hole.
Some modern plants use electric melters to achieve more stable melting conditions.
Typical parameters:
Temperature: 1500 – 1600°C
Power consumption: 600 – 900 kWh per ton
Production capacity: 5 – 20 t/h
Electric melting systems offer improved control of melt chemistry and reduced emissions compared to coke-fired cupola furnaces.
After melting, the molten rock is directed to the fiberizing system, where it is converted into fine mineral fibers.
Most modern rock wool plants use high-speed spinning fiberizers.
Typical fiberizing system parameters:
Spinner speed: 3500 – 4500 rpm
Spinner diameter: 250 – 400 mm
Fiber diameter: 4 – 7 μm
Air or steam blowing pressure: 0.3 – 0.6 MPa
Molten rock is fed onto rapidly rotating spinner wheels. Centrifugal force throws the molten material outward, forming thin fibers. High-velocity air streams further stretch the fibers and guide them toward the collection chamber.
The stability of spinner speed and melt flow rate directly affects fiber thickness and product density.
During fiber formation, a binder solution is sprayed onto the fibers.
Typical binder components include:
phenolic resin
curing agents
mineral oil (dust suppression)
water
Binder content usually ranges between:
2 – 4% of final product weight
The fibers then accumulate on a moving collecting conveyor, forming a continuous mineral wool mat.
Adjustable suction fans beneath the conveyor help distribute the fibers evenly and control product density.
Typical density range of the mat:
40 – 200 kg/m³
depending on the final product specification.
To achieve uniform fiber distribution, many production lines use a pendulum distributor system.
The pendulum oscillates laterally while depositing fibers onto the conveyor belt.
Typical parameters:
Pendulum swing width: 1000 – 2400 mm
Swing frequency: 20 – 60 cycles per minute
This movement ensures consistent density distribution across the entire width of the rock wool board.
The collected mineral wool mat then enters the curing oven, where the binder polymerizes and the final product thickness is stabilized.
Typical curing oven parameters:
Oven length: 20 – 35 meters
Temperature: 200 – 250°C
Conveyor speed: 3 – 10 m/min
Pressure range: 0.3 – 0.8 MPa
Inside the curing oven, hot air circulates through the fiber mat, curing the binder and giving the product its structural strength.
The oven also includes adjustable upper and lower belts to maintain precise thickness control.
Typical thickness tolerance:
±1 mm
After curing, the continuous mineral wool slab is cut into finished products.
Typical cutting equipment includes:
cross cutting saw
longitudinal cutting machine
edge trimming units
Cutting parameters typically include:
product thickness: 30 – 200 mm
board width: 600 – 1200 mm
cutting accuracy: ±2 mm
Some production lines also include additional equipment for producing pipe sections or lamella boards.
Finished products are automatically stacked and compressed for packaging.
Typical packaging process:
automatic stacking system
compression packaging
shrink wrapping
Compression ratios can reach:
up to 1:3
which significantly reduces transportation cost.
Several parameters must be carefully controlled to ensure stable rock wool production.
Fluctuations in furnace temperature may lead to inconsistent fiber formation.
Higher spinner speeds produce thinner fibers, improving insulation performance but increasing equipment wear.
Uniform binder application is essential for mechanical strength and dimensional stability.
Proper control of fiber distribution and conveyor speed determines final product density.
The rock wool manufacturing process involves a series of highly coordinated steps, from basalt melting and fiber formation to curing and cutting. Modern rock wool production lines rely on precise control of furnace temperature, fiberizing parameters, binder distribution, and curing conditions to achieve consistent product quality.
With increasing global demand for fire-resistant and energy-efficient insulation materials, advanced rock wool production technology continues to evolve, focusing on higher efficiency, improved fiber quality, and reduced energy consumption.
For manufacturers planning to invest in a rock wool production line, understanding these technical processes is essential for selecting the right equipment configuration and achieving long-term production stability.
Hebei Guangxing Machinery Technology Co., Ltd (Guangxing), established in 1987, is one of the leading Rock Wool Production Line Supplier China and manufacturers of EPS, PU/Phenolic/Rock/Glass wool insulation panel production equipment. Guangxing enjoys a strong reputation both domestically and internationally and holds CE and ISO 9001:2008 certifications, with over 20 patents.
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