Description
Anthracite for water filters
Anthracite is the highest rank of coal. It is a very hard and lustrous coal, also called “hard coal”, containing a high percentage of fixed carbon and a low percentage of volatile matter. In water treatment it is only used as a filter medium for suspended solids. Due to its hardness and characteristics, it is very difficult to activate in order to produce activated carbon.
- Raw material: Coal.
- Color: Black.
- Presentation: 1 ft3 (22.6 kilograms) bags.
Applications:
- Drinking water filtration
- Tertiary wastewater filtration
What is anthracite? What is it for?
This mineral is generated from vegetable matter that carbonizes due to the effect of sediments that generate an increase in pressure and temperature. After being subjected to strong conditions and long geological periods, the hardness of the material and its carbon content increases, going from peat and lignite to bituminous coal, to finally give way to the formation of anthracite by metamorphosis processes.
Anthracite is an excellent filtration medium for water clarification in potable or industrial use, when used in combination with filter sands. It is a mineral coal, black in color, shiny, with great hardness, it has a higher carbon content, up to 95%.
Due to the special shape of its grains, it allows the material in suspension to be retained in the depth of the filter bed. Compared to a sand filter, this media allows for higher flow performance in the filter, less pressure drop and better and faster backwashing.
Specifications:
| Property | Specification | Standard | |
| Color | Black | NA | |
| Density (g/cm3) | 0.8 – 0.83 | NA | |
| Apparent specific gravity (min.) | 1.5 | ANSI/AWWA B100 and ASTM C128 | |
| Hardness (Mohs scale, min.) | 2.7 | NA | |
| Effective particle size (mm) | #1 | 0.60 – 0.80 | ANSI/AWWA B100 and ASTM C136 |
| #1.5 | 0.85 – 0.95 | ||
| #2 | 1.70 – 2.00 | ||
| #4 | 7.95 – 14.29 | ||
| #6 | 20.64 – 41.28 | ||
| Uniformity coefficient (max.) | #1 |
1.7
|
ANSI/AWWA B100 and ASTM C136 |
| #1.5 | |||
| #2 | |||
| Grain size (approx.) | #1 | 14×30 | ANSI/AWWA B100 |
| #1.5 | 10×20 | ||
| #2 | 4×12 | ||
| Solubility in acid (%, max.) | 5 | ANSI/AWWA B100 | |
High purity and chemical stability
Anthracite is characterized by its high purity, composed mostly of fixed carbon, with minimal amounts of volatile materials and non-carbonized substances, which gives it high chemical stability.
Its resistance to chemical alteration makes it ideal for use in filtration, since it does not introduce additional contaminants to the water and maintains its filtration properties over a wide range of pH values.
Porous structure and optimum density
Anthracite is a carbonaceous material that has undergone metamorphosis to the point of acquiring a highly porous physical structure. The network of pores allows water to flow between them, providing multiple points of contact for the interception and retention of suspended and colloidal particles.
Anthracite has a density that is significantly lower than that of other granular filter media. Due to its low density, it is placed in the upper layers to optimize the flow and filtration of water in the following media, as it retains larger particles.
Long service life due to its resistance
Anthracite is a hard material and resistant to abrasion. This hardness allows it to maintain its physical integrity under the mechanical conditions of the filtration process, such as water pressure, movement, and particle load. Unlike other softer filtering media, which can wear out or decompose over time, anthracite tends to retain its shape and grain size.
Thanks to these characteristics, it minimizes the effects of water pressure in lower layers, such as the compaction of sand.
Backwash flow
It is reduced. Due to its unique density, anthracite can be used in multimedia or deep bed filters. At a density of 50 lbs/ft, it is hydraulically suitable and will outperform heavier media such as filter sand.
Related articles: What are the types of coal? – Learning Center
More information: All about Anthracite – Filtrashop
