Fuel and related compositions – Liquid fuels – Aluminum or heavy metal – other than lead – containing
Patent
1982-05-27
1984-11-27
Dees, Carl F.
Fuel and related compositions
Liquid fuels
Aluminum or heavy metal, other than lead, containing
44 15R, 209 5, 241 20, C10L 910, B03D 306
Patent
active
044849281
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the preparation of fuels and, more particularly, to fuel preparation processes which are unique in that they can be employed to produce coal-type fuels which have an extremely low (<1.0 wt%) ash content and essentially no pyritic sulfur.
DISCLOSURE OF THE INVENTION AND BACKGROUND ART
In general, this novel, and economically important, result is obtained by milling or otherwise comminuting raw coal until it has been reduced in particle size to ca. 250 .mu.m.times.0 (.mu.m equals micrometer or micron). The raw coal is then slurried in an aqueous liquid, typically clean water; and comminution of the raw coal is continued until the raw coal has been resolved into separate, particulate phases of coal and mineral matter. After this comminution step is completed, a large amount of an agglomerating agent is added to the slurry with agitation; agitation of the slurry is continued until the coal particles have dissociated from the mineral matter and aqueous phases of the slurry and coalesced into agglomerates of product coal; and the agglomerates are recovered from the slurry (there is virtually 100 percent recovery of the carbonaceous material in this separation).
A product coal with an even lower ash content than is available from following the steps identified above can be produced by redispersing the product coal agglomerates in clean water and repeating the agglomeration and collection steps. This sequence can be repeated as many times as wanted although it is presently believed that the benefits obtained by proceeding beyond the third collection step will in general not justify the expense of doing so.
No additional milling is required in the second product coal recovery stage (dispersion, agglomeration, and recovery steps) just discussed or in subsequent repetitions of this sequence of steps. Consequently, the elimination of additional ash afforded by the second (and any subsequent) stages can be effected inexpensively and with only modest expenditures of energy.
Still another technique that can be employed to reduce the ash content of the product coal obtained in the initial (or a subsequent) agglomeration and separation of the product is an acid leach of the product coal.
All of the above-discussed process steps can be carried out at ambient pressure and at ambient temperatures (preferably 70.+-.10.degree. F. (21.2.+-.5.6.degree. C.)).
The process described above can be used to prepare fuels which can compete directly with Bunker C and residual crude oils and synthetic coal fuels which have been successfully employed to fuel gas turbine engines. The flame characteristics of these novel fuels lie between those of flames obtained by burning natural gas and No. 2 fuel oil, respectively.
Specifically, product coals with ash contents of substantially less than 1.0 weight percent have been produced by the foregoing process with demonstrated repeatability from a number of quite different coals. These fuels typically have the following characteristics:
______________________________________ Particle Size down to 4 .mu.m .times. 0
Ash down to 0.22 wt %
Moisture below 5 wt %
BTU/lb in the range of 15,000
BTU Percent Yield approaching 100%
______________________________________
Small particle size is an important contributing factor to the usefulness of a coal-type fuel. The process described above is eminently capable of generating such fuels as is shown by the foregoing tabulation.
As indicated above, the raw coal being processed into a low ash fuel as disclosed herein is preferably first milled or comminuted while in a "dry" state, formed into an aqueous slurry, and then subjected to further size reduction. Unexpectedly, it has been found that this is economically advantageous while the efficiency of the process is not adversely effected by the dry milling contrary to what is stated in U.S. Pat. No. 4,186,887 which was issued Feb. 5, 1980, to Douglas V. Keller, Jr., et al and which discloses an agglomeration type coal recov
REFERENCES:
patent: 4083940 (1978-04-01), Das
patent: 4186887 (1980-02-01), Keller, Jr. et al.
patent: 4217109 (1980-08-01), Siwersson et al.
patent: 4244699 (1981-01-01), Smith et al.
patent: 4248698 (1981-02-01), Keller, Jr.
patent: 4249699 (1981-02-01), Smith et al.
Dees Carl F.
Otisca Industries, Inc.
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