Anthracite
Filtration anthracite is made by crushing and screening hard, carbon-rich coal. The spaces between its angular grains allow water to pass while retaining suspended solids.
Its primary role is physical filtration. It is not prepared for adsorption like activated carbon; grain size and density determine its position alongside other materials in a multimedia bed.
Technical Specifications
| Material type | Filtration anthracite |
|---|---|
| Grain structure | Angular granules |
| Colour | Black |
| Fine-grade effective size range | 0.6–0.8 mm |
| Bulk density | 780 kg/m³ |
| Apparent particle density | 1.6 g/cm³ |
| Carbon content (ash- and moisture-free) | 94% |
Application and use
- In water-treatment filters, anthracite retains suspended solids before downstream treatment.
- In a multimedia bed, it forms the upper layer above denser sand or garnet.
- Backwashing removes accumulated solids; the available wash flow and expansion space must suit the selected grain grade.
Frequently asked questions
Can anthracite be added to an existing sand filter?
It can be considered if the vessel has room for an upper layer, suitable lower layers and bed expansion during backwash. Review the existing bed depths and freeboard.
Which anthracite grade should I choose?
Compare effective size, full size distribution and uniformity coefficient against the other layers. A grade name alone does not establish equivalence.
Is the existing backwash pump sufficient?
Compare the chosen grade's backwash flow and expansion needs with the pump's delivered flow and available vessel freeboard.
How much anthracite does the bed need?
Calculate the quantity from vessel area and selected bed depth. Preserve separate freeboard for backwash expansion.
Can anthracite replace activated carbon?
Not as a general substitution. Anthracite is selected for solids filtration; adsorption of dissolved substances requires a separately specified activated-carbon duty.