Fuel and related compositions – Carbonized component
Patent
1998-10-13
2000-10-03
Howard, Jacqueline V.
Fuel and related compositions
Carbonized component
44620, 44628, C10L 500
Patent
active
061267058
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates generally to the recovery of clean coal from coal tailings and in particular to the production of useful coal product from coal fines.
BACKGROUND ART
Solid carbonaceous materials, such as coal, have long been employed as a fuel source whether it be by simple combustion or conversion into a gaseous or liquid fuel. Certain coals when suitably processed into coke also provide an essential raw material in iron making.
All coals contain mineral particulates to some degree. Excessive levels of such mineral particulates are undesirable as they interfere with the combustion of the coal and the formation of coke. The particulates also lead to undesirable increases in ash levels during processing and combustion. Prior to utilisation, most coals have traditionally undergone a washing treatment. During such a treatment, finely divided coal or coal fines of varying sizes are washed into the waste water together with the mineral particulates and other gangue materials. These coal tailings are typically held in settling ponds on the mine site. In addition to representing a loss of coal, the disposal of the waste water can represent an environmental hazard.
It would be desirable to provide a new means of processing coal slurries that provided desirable beneficiation of coal fines and the production of a coal product that could be readily handled and, if desired, further processed as required. It would also be desirable but not essential that the new process in providing this improved beneficiation had a cost of production similar to or not significantly higher than presently used processes.
SUMMARY OF THE INVENTION
According to a first aspect, the present invention consists in a process for the treatment of coal tailings containing coal particles, comprising the steps of: particles; and to recover a semi-coke or coke product.
In one embodiment of the first aspect of the process, following step (ii) the separated coal particles can undergo an agglomeration step, with the agglomerated coal particles then undergoing the heat treatment process in step (iii).
According to a second aspect, the present invention consists in a process for the treatment of coal tailings containing coal particles, comprising the steps of: coal particles having sizes between about 75 microns and about 2 mm; proportion of coal particles having sizes less than about 75 microns; (ii) with the coal particles recovered by the treatment process in step (iii); and recover a semi-coke or coke product.
In one embodiment of the second aspect of the process, the coal particles recovered by the treatment process in step (iii) can undergo an agglomeration step, with these agglomerated coal particles then being mixed with the coal particles recovered by step (ii), and then subjecting the mixture to the heat treatment process in step (v).
The step of agglomerating the coal particles removed from the coal tailings in the above aspects of the invention comprises mixing with the slurry or coal particles in a suitable vessel a suitable oil and removing the agglomerates so produced. This process step relies on the fact that certain coals are hydrophobic or can be rendered hydrophobic so that when coal particles are mixed with the oil, the coal preferably collects in the oil phase and can be recovered leaving the remaining hydrophilic constituents of the slurry in aqueous suspension.
The oil that can be used in this step can consist in a wide variety of liquid hydrocarbons including kerosene, diesel oil, fuel oil and petroleum residues through to heavy aromatic materials such as coke oven tars and bitumen together with various mixtures thereof.
The slurry may be pre-heated prior to mixing with the oil and the oil may also be hot when added to the slurry.
In the above aspects of the invention, the coal particles or agglomerates also undergo a heat treatment process. In the case of the agglomerates, these are preferably heated to a temperature at least sufficient to ensure that a majority of the oil used in the a
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patent: 5676710 (1997-10-01), Chedgy
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Patent Abstracts of Japan, p. 130, JP A 54-134703 (Shin Nippon Seitetsu K.K.), Nov. 4, 1978.
Patent Abstracts of Japan, p. 106, JP A 05-163494 (Nippon Steel Corp.), Dec. 13, 1991.
Lees Jeremy James
Pryor Murray Howard
Howard Jacqueline V.
Ilecard Pty Ltd
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