Stone Wool is made
Glass Wool is made
required amounts of raw material are measured and sent to a
melting furnace. For stone wool this is the rock or recycled
material plus energy. Manufacturers are working hard to increase
the recycled content of mineral wool whilst maintaining the high
quality of their product.
For glass wool the raw materials are sand, limestone and soda
ash, as well as recycled off cuts from the production process.
Recycled window, automotive or bottle glass is increasingly used
in the manufacture of glass wool and it now accounts for 30% to
60% of the raw material input. In some plants this is as high as
The reuse of off cuts and recycled materials has helped to
steadily reduce the energy input required to produce mineral
- The raw materials are melted in a
furnace at very high temperatures, typically 1300°C to 1500°C.
The smoke that is created during this process is filtered and
flue gases cleaned to minimise any environmental impact.
- After the furnace droplets of the
vitreous melt are spun into fibres, droplets fall onto rapidly
rotating flywheels or the mixture is drawn through tiny holes in
rapidly rotating spinners. This shapes it into fibres.
- Small quantities of binding agents are
added to the fibres. The structure and density of the product
can be adapted to its precise final usage.
- This is then cured at around 200°C.
- The mineral wool is sawn to the
required size and shape, for example into rolls, batts, boards
or it is customised for addition to other products. Off-cuts and
other mineral wool scraps are recycled back into the production
- Due to its impressive elasticity,
mineral wool can be compressed to reduce its volume during
packaging, making it cheaper and easier to transport and handle.
Gases and waste
- Waste such as off-cuts are recycled
into the production process reducing inputs and energy
- Gases from the production processes
are cleaned in filters and after-burners to minimise impact on