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260 Advances in Productive, Safe, and Responsible Coal Mining

0.7

0.6
CCPW
0.5
Percent extraction 0.4 CCPW/FCPW

CCPW/FCPW/Lime-
0.3
0.2 stone

0.1

0.0
Aluminium Cadmium Calcium Chloride Copper Iron Lead Magnesium Manganese Nickel Potassium Sodium Strontium Sulfur Zinc

Element

Fig. 13.6 Elemental extraction throughout entire 19-month kinetic test period [2].

however, developing similar technologies for fine coal and refuse particles has been a
“holy grail” topic in the mineral processing industry for decades. Thanks to the relent-
less pursuit of that quest, several options are available. They can be broadly classified
as thermal drying, sedimentation, and filtration [1]. Thermal drying is the application
of heat to evaporate water. Although very effective, it is rarely used due to the high
cost of supplying the thermal energy involved and the safety hazards associated with
heating carbonaceous material. Sedimentation is the rapid settling of solid particles in
a liquid that produces a clarified liquid and a thickened slurry. It is most efficient
when there is a large density difference between liquid and solid; for example, water
(SG¼1.00) and pyrite (SG¼4.95). Particle settling in sedimentation may be aided
by centrifugation or the use of chemicals that cause particles to adhere to each other.
Filtration uses a porous medium to retain solid particles while allowing liquid to pass
through. Filtration is often aided by mechanical pressure or vacuum suction.
Of the many options now available for dewatering FCPW, the authors have chosen
to highlight two. One, the deep cone paste thickener, is a commercially available
advanced sedimentation process; the other, osmotic dehydration, is an advanced fil-
tration process that is still being developed.

13.2.2.1 Paste thickening
As coal mining has become more mechanized, the percentage of fine material in ROM
product has increased leading to various technologies being developed for separating
the fine fraction into product and waste streams. With few exceptions, these