Parnaby Cyclones with over 50 years of experience is a key partner in maximizing the efficiency of coal preparation.
Systems have been developed for washing and separating different grades of coal, the recovery of fine coal particles and the treatment and disposal of effluent.
Washing and separation of coal improves its saleability. The end product has:
- higher calorific value
- lower ash content
- potentially lower sulphur content
There are two main systems for the processing of coal. The first uses a natural medium (water and raw material) and secondly a dense medium (with magnetite added).
Natural Medium Washing Plant
The natural medium washing plant is the most cost-effective coal preparation method of processing easily separated coals, in particular run of mine coal for industrial use, and
recovering coal from colliery waste.
The plant uses four types of separating
- Dewatering Screens
- Sieve Bends
Processing and Treatment Flow Diagram – Natural Medium Washing Plant
Natural Medium Cyclone
Cyclone-only plants can be supplied for washing small coal below 50mm particle size.
In the cyclone, the small particles are separated by centrifugal and vortex action (the cyclone itself does not move). The water/particle mixture is pumped into the side of the cyclone tangentially and swirls around creating a vortex in which the lighter coal particles are sucked to the middle (and out to a dewatering screen).
The heavier shale particles are thrown by centrifugal force to the wall of the cyclone and are discharged at the opposite end.
Dense Medium Washing Plant
The dense medium washing plant is the most efficient separation process available. It is ideally suited for:
- Separation of difficult coal types
- Washing and production of high value products for domestic and industrial markets
The overall process differs from the natural medium plant because the medium is created using magnetite(fine iron particles) instead of the fine particles in the raw material. This allows for more exacting control and a wider range of separation gravities.
Small and fine particles are removed from the raw material before it is fed into the drum. Initially it passes over a dry screen to remove particles smaller than 10mm, then any remaining fine particles/slimes (smaller than 3.0mm) are removed by a vibratory rinsing and dewatering screen. The small particles are then separated in a classifying cyclone.
Alternatively the fine particles can be separated in a fines recovery plant.
The Parnaby dense medium washing plant can efficiently separate raw material from a wide range of proportions. Other benefits include:
- 2 OR 3 Product Separator Drum
- Low Power Requirement
- High Efficiency Process Separation
- Low Magnetite Consumption
- Robust Modular Design
- Quick to Assemble, Easy to Move
- Can Easily be Enclosed in a Building
- Extensive Product Range
- Single Drum Capacity up to 250TPH
A three product separator drum is also available which has a second chamber which repeats the process (at a higher separation gravity) thus producing prime coal, middling’s and shale.
One combined cyclone and dense medium drum plant can process up to 500 tph of coal up to 200mm particle size.
Dense medium cyclone- only plants can be supplied for washing small coal below 50mm particle size.
Fines Coal Recovery Unit
The Natural and Dense Medium Washing Plants can recover coal as small as 0.5mm particle size. Smaller particles pass through the screens and drain to the effluent sump.
We have developed a range of fines coal recovery plants to treat the overflow from the washing plant before it goes for effluent treatment. These plants can recover and dewater coal particles down to zero particle size.
There are four types of fines coal recovery plants available:
- Water-only cyclone
- Gravity Spiral
- Froth Flotation Process
Click here for details of our coal preparation equipment