Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L5/00—Solid fuels
  • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
  • C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
  • C10L5/10—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders

Definitions

• the present invention concerns a briquetting process. More especially it concerns such a process which gives improved cure rate and green strength in "cold" briquetting, that is briquetting at temperatures of up to 100°C.
• magnesium oxide accelerates the rate of cure. Magnesium oxide has been found, in particular, to impart a significant improvement to the green shatter resistance of molasses/phosphoric acid bound briquettes.
• the present invention provides a process for the cold briquetting of fine coal, comprising mixing fine coal with a binder utilising phosphoric acid to produce a water-containing briquetting mix, and characterised by the presence in the briquetting mix, preferably in an amount of up to 2% by weight of the mix of magnesium oxide, and briquetting the mix, whereby the green shatter strength, the hot crushing strength of the resulting briquettes during curing and/or the water resistance of the cured briquettes are improved.
• the binder is a combination of molasses and optionally an organic hardening agent, or a sugar solution, together with phosphoric acid and we refer to our prior applications mentioned above for examples of such binders.
• Molasses/phosphoric acid binder is particularly preferred.
• Preferred coals are high rank non-caking coals, especially those having low smoke emissions such as anthracite.
• the coal is of a particular size mainly below 3mm, and anthracite duff is especially suitable.
• the invention is also applicable to coals for power stations or steam raising and to coal blends containing coking coal components and/or treated coals, e.g. by mild oxidation or pyrolysis.
• the coal may be crushed or be the direct product of coal cutting.
• the briquetting step of the present invention includes all methods of forming agglomerates from fine coal, and these agglomerates may be of any size or shape according to market requirements. There may be mentioned forming agglomerates by extrusion, ringroll or roll-pressing, die-pressing, rotary table pressing and pelletising, e.g. on a disc pelletiser.
• the hardening (curing) stage in the briquetting process is preferably carried out at temperature of the order of 200 o C to 300 o C for up to an hour.
• Hot curing may be conveniently carried out by passing the briquettes on a conveyor through an oven, in an atmosphere which may contain nitrogen, carbon dioxide, water vapour and/or oxygen.
• Anthracite duff (88 parts, - 1.7mm particle size) was mixed with iron ore (1 part) and binder (11 parts) by weight.
• the binder was a mixture providing molasses (10 parts) and phosphoric acid (1 part).
• the mixture was briquetted in a pilot plant roll press, and the briquettes produced were tested for green crushing strength, green shatter resistance, hot crushing strength (at 250oC) and water resistance.
• the properties of the control mix were compared with those of a similar mix containing 1% w/w of magnesium oxide additive.
• the results shown in the attached table indicate a significant increase in the green shatter resistance and hot crushing strength of the briquettes and in their water resistance. Similar results were obtained whether the magnesium oxide additive was added before or after the binder.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Geology (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Solid Fuels And Fuel-Associated Substances (AREA)

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Cited By (5)

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Citations (3)

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• 1989
  • 1989-01-12 GB GB8900631A patent/GB2227023A/en not_active Withdrawn
  • 1989-12-20 ZA ZA899782A patent/ZA899782B/xx unknown
  • 1989-12-21 EP EP19890313406 patent/EP0377995A3/fr not_active Withdrawn

Patent Citations (3)

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