Waste mineral fibre is generally “off-spec” mineral fibre products generated by the manufacturers of mineral or glass wool. Providing the waste material is a clean, consistent mineral fibre, it is generally suitable for use in the manufacture of ceiling tiles or in other applications.
The waste mineral wool/fibre is used as a direct substitute for other mineral fibres, and is dispersed in a solution of cold water, before being blended with the other fillers and binder ingredients. The mass is then formed into a continuous mat before being cut into sheets for drying. The dried sheets are then fabricated, “finish coated” and cut to final size.
Mineral fibre ceiling tiles contain up to 75% recycled content (6, 7). The content of recycled mineral fibre is not clear. However, levels of substitution of new fibre by waste fibre could be as high as 100% by weight, (the tile may be 25 to 75% mineral fibre). Ceiling tiles have a range of performance characteristics which can include resistance and reaction to fire properties, acoustical absorption and attenuation, light reflectance, basic physical strength and durability. The content and type of mineral wool used in these products will impact on these characteristics. The ceiling tile manufacturing industry has a history and willingness to utilise byproducts and has often replaced virgin raw materials with (usually) lower cost alternatives. The use of blastfurnace slag (from iron smelting) as the main mineral input into the melting and spinning process for mineral wool, as an alternative to quarried rock is one example. Starch recovered from the potato snack industry has been used as an alternative binder to virgin material in the manufacture of ceiling tiles.