Fuel and related compositions – Liquid fuels – Aluminum or heavy metal – other than lead – containing
Patent
1984-12-26
1986-10-21
Dees, Carl F.
Fuel and related compositions
Liquid fuels
Aluminum or heavy metal, other than lead, containing
44 16R, C10L 510, C10L 520
Patent
active
046183477
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the preparation of combustible fuel materials, suitable for domestic or industrial heating, in briquette form. Fuels for these purposes are, for example, peat, lignite, bituminous coal, anthracite, charcoal and sawdust.
In the manufacture of fuel briquettes, it is known to use coal tar pitch as a binder with coal dust, so as to hold it together when shaped under pressure in a briquetting press. However, coal tar pitch is becoming scarce and hence expensive. Bitumen has been used as an alternative but, after mixing with the coal dust, it must be cooled quickly to prevent it forming into coke. Furthermore, briquettes incorporating pitch or bitumen are unsuitable for use in modern glass-fronted fires because the smoke emitted, on ignition, discolours and stains the glass. More particularly, they are totally unacceptable for use in so-called "smokeless zones", the demand for which is rapidly increasing, for environmental reasons and especially owing to the awareness of health hazards caused by the emission of smoke into the atmosphere.
Therefore, if coal tar pitch or bitumen is to be used in the production of briquettes for smokeless fuel from, for example, anthracite duff (dust), the briquettes have to be defumed in a slow heat process in which the smoke content is gradually burned off without charring the briquettes. This additional step adds considerably to the cost of manufacturing the briquettes.
Phenolic resins and pre-gelling starches have been used as binders but, again, a heating stage is required in the manufacturing process, in order to dry off the very high moisture content and to set the briquettes.
Further processes for manufacturing fuel briquettes are described in U.S. Pat. No. 2,922,705 and GB-A No. 1059679. In the former description, an organic acid such as acetic acid is added to particulate coal. The method described in the latter comprises mixing briquetting coal, urea, formaldehyde and spent sulphite lye, e.g. a lignosulphonate, before pressing and briquetting; the lye may be sufficiently acidic to catalyse urea-formaldehyde condensation, or an organic or inorganic acid may be added.
As a binder for fuel briquettes, lignosulphonates have been used both in a hot process (i.e. a process incorporating a heating stage), and also in a cold process. In the latter case, the briquettes produced have generally had very poor resistance to pressure or impact. In attempts to strengthen the briquettes, and as disclosed in GB-A No. 992155, sodium dichromate has been added to a coal/binder mix, but the resultant briquettes have very poor green strength and can be damaged or disintegrated easily for quite some time after formation. The result is that they cannot immediately be packed or stacked in piles, but must be carefully spread in very shallow layers and left to harden for days before they are sufficiently firm to withstand the abuse realistically to be expected during subsequent packing, stacking or transportation. It is generally the case that anthracite briquettes are too liable to disintegrate, for satisfactory commcerial use.
The gelling reaction between lignosulphonate and dichromate has been extensively studied. Hayashi et al., in one of a series of papers published in what appears to be the Journal of the Japan Wood Research Society, specifically 12 (1966) 300-305, report that lignosulphonate is oxidised by dichromate during gelling, and it is also suggested that Cr (VI) would be reduced to Cr (III) by vigorous heating or by treatment with a strong acid such as sulphuric acid. This report gives no suggestion that the lignosulphonate gel is of practical value, and concludes by stating that the gel hardens very slowly after formation, e.g. over at least two weeks.
DD-A No. 0049325 discloses that a water-insoluble gel can be obtained from lignin sulphonate and chromic acid or its salts, and claims the use of a waste chromic acid source. The "chrome-lignin" reaction is disclosed in "The Chemistry of Cement and Concrete", ed. Lea, Pub. Edward Arnold (Publishers) Ltd., 3r
REFERENCES:
patent: 969504 (1910-09-01), Trainer et al.
patent: 1084479 (1914-01-01), Platsch
patent: 1596239 (1926-08-01), Delzeit
Watt George
Young George E.
Dees Carl F.
Parkhurst Todd S.
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