Perlite in the natural state is a dense, glassy rock formed by volcanic action. When crushed and treated under proper conditions, it pops like popcorn, expanding to 20 or more times its original volume. A special milling and classification process gives Dicalite® perlite filter aids the structure and correct particle size range distribution needed for optimum performance.
Perlite is an amorphous mineral consisting of fused sodium potassium aluminium silicate. Dicalite® perlite filter aids are processed at temperatures exceeding 800 °C (1500 °F) which eliminates organic matter. They have extremely low solubility’s in mineral and organic acids at both low and high temperatures.
Solubility’s in strong alkalis will vary according to temperature and time of contact. Dicalite® perlite filter aids do not impart taste or odour to liquids being filtered.
A major advantage of Dicalite® perlite filter aids is that most weigh less per unit volume than standard diatomite filter aids. Pound for pound, this gives up to 20% greater filtering capacity resulting in comparable savings in filter aid usage, especially on rotary vacuum pre-coat filters.
|Rock structures||Classical perlite|
|Bulk Density||900 – 1100 kg/m3|
|Moisture||max. 1 %|
|pH||6 – 8.5|
|Major Elements||Typical Range in %|
Softening point890 – 1100 °C
|Loose Weight Density||35 – 45 kg/m3|
|Tamped Weight Density||55 – 60 kg/m3|
|Free Quartz||< 0.5 %|
|Mechanical Resistance||0.6 – 1.51 kg/cm2/cm|
|Thermal Conductivity λs =||0.034 – 0.042 W/(m.K)|
|Fusion point||1280 – 1350 °C|
|Specific gravity||2.2 – 2.4|
|Fire resistance||Perlite is non-combustible|
|Product||PFRv min.||PFRv max.||PCD min.||PCD max.||Float max.||Pkg net kg||Data Sheet nr.|
Permeability Flowrate (PFRv)
- The constant volume filtration flowrate is measured by the permeability method (S.T.M. Nr. I-9).
- This relative value gives an idea of the filtration speed.
- It is the fundamental characteristic which differentiates one filteraid grade from another when the particles are formed into a filter bed or cake. Permeability is related to particle size distribution.
Permeability Cake Density (PCD)
- The wet cake density is also measured by the permeability method (S.T.M. Nr. I-9).
- This value gives the wet cake density in lbs/ft³ (x16 » kg/m³).
- Perlite filteraids form lower density cakes than diatomite filteraids of comparable permeabilities. Densities of Dicalite® perlite filteraids are controlled at a level found to be optimum for most effective performance.
- The float is measured by S.T.M. Nr. O-4
- This value gives the amount of floating particles in ml/20g
Perlite Functional Fillers
Dicalite® perlite functional fillers are a versatile family of mineral-based silicate products available throughout the world. A specialised Dicalite® process incorporating expansion, selective milling, and sizing determines the particle shape of each filler product. A variety of flake or di-, tri-, and tetrahedral particle shapes are obtained by this exclusive process. These unique shapes provide numerous functions including high surface area, permeability and reinforcement and have densities among the lowest of any of the mineral fillers. In addition to superior spatial loading, this property affords customers the added bonus of density control in their finished products. Dicalite® perlite fillers are off-white and do not interfere with the colouring of the products into which they are formulated.
Dicalite® perlite fillers are inert to all but strong acids or alkalis and have no residual surface reactivity. After processing they are free of any organic contamination.
Dicalite® offers several grades of perlite functional fillers, the most popular of which are described in the table below.
|Product||Screen An.* 325 (%)||Screen An.* 140 (%)||PCD min.||PCD max.||Float max.||Pkg net kg||Pkg length (cm)||Pkg colour||Data Sheet nr.|
* Retained on U.S. Std. Sieve 325 Mesh = 0.044 mm, 140 Mesh = 0.105 mm (wet screening).