FUEL BRIQUETTES

Abstract: The briquette comprises carbonaceous fuel particles (such as anthracite duff) bonded together by means of a binder comprising molasses in an amount of at least 5%, based on the weight of the briquette, and a minor amount of an inorganic hardening agent for the molasses, the hardening agent comprising an alkali metal phosphate and/or an alkaline earth metal sulphate.

Description: The present invention is concerned with fuel briquettes and, in particular, briquettes made from carbonaceous fuel particles, such as powdered fine coal. Coal briquettes are conventionally formed by bonding coal particles using an organic binder; many such binders have been proposed, including molasses, which is known for use in a low temperature briquetting process. Various inorganic hardening agents have been proposed for the molasses binder, such as lime (GB 2181449), phosphoric acid (GB 230306), calcium phosphate, ferric oxide, calcium carbonate and/or aluminium oxide (GB 2187754), and plaster of Paris (FR-A-326 283). We have now devised alternative inorganic hardening agents for a molasses-based binder for use in making fuel briquettes. Broadly, the present invention relates to a fuel briquette comprising carbonaceous fuel particles bonded together by means of a binder comprising molasses in an amount of at least 2% by weight, based on the weight of the briquette, and an inorganic hardening agent for the molasses, the hardening material being present in a minor (hardening) amount, relative to the weight of the molasses. According to the present invention the hardening agent is present in an amount of 0.02 to 5% by weight, based on the weight of the briquette and comprises an alkali metal phosphate together with phosphoric acid and/or sulphuric acid. The alkali metal phosphate is preferably pentasodium triphosphate (sodium orthophosphate). The molasses is preferably present in an amount of 2 to 20% by weight (such as 5 to 15%) based on the weight of the briquette. Typically the phosphoric acid is present in an amount not exceeding 2% by weight of the briquette. It is preferred that the binder should be substantially free of synthetic polymer binders; the molasses used as the binder may be cane or beet molasses. The carbonaceous fuel used in the briquettes according to the present invention may be charcoal, coke, or coal. The preferred fuel is a high rank non-caking coal, typically of the low smoke type, such as anthracite. The fuel generally has a particle size below 3mm; anthracite duff is particularly preferred. Other coals which may be used are steam coals. and heat-treated coals. The briquettes according to the invention may be formed as agglomerates by extrusion, ring roll or roll pressing, die pressing, rotary table pressing or pelletising. The green briquettes may be allowed to harden, for example, at room temperature over one to three days, or cured at elevated temperature (e.g. at 200 to 300°C for up to one hour). This hot curing may be carried out in an over containing an inert or partially inert atmosphere. In order that the present invention may be more fully understood, the following Examples (in which all percentages are by weight) are given by way of illustration only. Example 1 Anthracite dust was dried, crushed and screened to approximately 3mm, and then mixed with 8% molasses, 1% phosphoric acid and 0.3% sodium orthophosphate. The mixture was then forced into briquettes and cured at 260°C for one hour in an oxygen-controlled atmosphere. The resulting briquettes were substantially non-friable and had satisfactory water-resistance. Example 2 Example 1 was repeated, except that 0.2% of sodium orthophosphate was used. Similar results were obtained.

Claims: A fuel briquette comprising carbonaceous fuel particles bonded together by means of a binder comprising molasses in an amount of at least 2% and an inorganic hardening agent for the molasses in an amount of 0.02 to 5%, both percentages being based on the weight of the briquette, characterised in that the hardening agent comprises an alkali metal phosphate together with phosphoric acid and/or sulphuric acid. A briquette according to claim 1, wherein the molasses is present in an amount of 2 to 20% based on the weight of the briquette. A briquette according to claim 1 or 2, which is substantially free of synthetic polymer binders. A briquette according to any of claims 1 to 3, in which the carbonaceous fuel comprises charcoal, coke or coal. A briquette according to claim 4, in which the coal is a high rank, low-smoke non-caking coal. A briquette according to claim 5 wherein said coal is anthracite. A briquette according to any of claims 1 to 6, in which the fuel has a particle size below 3mm. A fuel briquette according to any of claims 1 to 7, which is formed by extrusion, ring roll or roll pressing, die pressing, rotary table pressing or pelletising.

Inventors: TAYLOR, DUNCAN
Applicants: RYAN INTERNATIONAL LIMITED
Application year: 1990
Main classification: C10L5
IPC codes: C10L5