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 OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • 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
  • C10L5/14—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders with organic binders

Definitions

• the invention relates to hard coal briquettes bound with starch or starch derivatives and having a reduced water absorption capacity, and to processes for producing such briquettes.
• bitumen or sulfite waste liquor in particular have hitherto been used as binders.
• both binders contain a high proportion of sulfur, so that considerable amounts of sulfur dioxide were produced when the briquettes were burned.
• DE-OS 3314764 describes a process for producing fuel briquettes in the presence of synthetic organic compounds as binders, using essentially solid fuel, polyvinyl alcohol and calcium oxide and / or magnesium oxide, in the presence of at least 1% by weight of water mixed together and formed into briquettes in a manner known per se by pressing. This requires about 0.5 to 2% by weight of polyvinyl alcohol, calculated as a dry substance and based on the solid fuel. The combustion exhaust gases of such briquettes contain significantly reduced SO2 contents.
• DE-OS 3445503 relates to a process for the production of briquettes from hard coal and a binder, in which aqueous alkali silicate solutions are used as binders, the solidification taking place by absorption of carbon dioxide and can additionally be accelerated by gassing with carbonic acid.
• DE-PS 1771433 discloses a process for the production of moldings from fine-grained substances, in particular fuels, in which sulfite waste liquor is mixed with higher-temperature solids, water-soluble adhesives, in particular molasses, starch and / or dextrins, being used as binders instead of the sulfite waste liquor be used.
• starch as a binder for briquetting fine coal is also described in DE-OS 3136163 and 3227395. 3 to 8% by weight of sulfite waste liquor or alternatively 1 to 3% by weight of starch, in each case based on coal, are mentioned as binders.
• DE-PS 1010950 shows a process for the production of fuel briquettes in which the starting material is treated with a binder obtained by reacting one or more higher carbohydrates or carbohydrate ethers with a dilute aqueous solution of a carboxylic acid, formed into briquettes under pressure and the Briquettes may be dried.
• starch and starch derivatives in particular have found particular interest.
• Starch is a product available at reasonable prices and in any quantity, which is characterized by particular environmental compatibility in handling and burning.
• a disadvantage of starch is its hydrophilicity. Briquettes bound with starch absorb water from their surroundings, reducing their compressive strength. This affects storage and handling strength in particular. The briquettes also lose calorific value due to water absorption. There is also the risk that briquettes bound with starch, which have a certain water content, will be attacked by microorganisms and mold will form.
• organopolysiloxanes for hydrophobizing inorganic or organic products has been known for a long time.
• silicones for this purpose, however, it is necessary to find silicone preparations which are effective even in small amounts.
• the silicone preparations should be as free of solvents as possible and reduce the water absorption of the briquettes in such a way that the desired storage and handling stability is given.
• the polysiloxanols of the formula I are essentially ⁇ , ⁇ -dimethylsiloxanols, although some methyl radicals can be replaced by phenyl radicals. However, at least 90% of the R 1 radicals are said to be methyl radicals.
• the average chain length of the polysiloxanols is given by the index n. It is 20 to 250, preferably 30 to 80, in particular 50 to 70.
• the silane of formula II is characterized by the presence of the reactive groups OR2 and R3.
• R2 is a lower alkyl radical having 1 to 4 carbon atoms and in particular a straight-chain lower alkyl radical.
• the ethyl radical is particularly preferred.
• the R3 radical is an aminoalkyl radical having 1 to 6 carbon atoms.
• Examples of such aminoalkyl radicals are the aminomethyl, ⁇ -aminopropyl and ⁇ or ⁇ -aminobutyl radical.
• R3 is preferably the ⁇ -aminopropyl radical.
• R3 can also have the meaning of the radical H2N- (CH2) x R4 (CH2) y -, where R4 is an oxygen, sulfur, ⁇ NH ⁇ or ⁇ NH-CH2CH2-NH radical, x ⁇ 3 and y ⁇ 2 is. Examples of this are the Leftovers H2N- (CH2) 3-NH- (CH2) 2 ⁇ , H2N- (CH2) 2-O- (CH2) 2 ⁇ , H2N- (CH2) 3-NH- (CH2) 2-NH- (CH2) 3 -.
• the radical R3 can also be an epoxyalkyl radical of the formula where n is an integer from 1 to 6.
• the glycidyl radical is in particular the epoxyalkyl radical prefers.
• the compounds of the general formula I and the general formula II are mixed with one another in such amounts that an SiOH group of the polysiloxanol corresponds to> 1 to 3 OR 2 groups.
• the molar ratio of 1 SiOH group of the polysiloxanol of the formula I to 2 OR 2 groups of the silane of the formula II is preferred. Reaction products which are obtained when a ratio of 1 SiOH group to 1 SiOR 2 group is observed clearly show poorer properties in reducing the water absorption capacity of the briquettes.
• the organopolysiloxane obtained can be used in the form thus obtained or as an aqueous dispersion.
• a suitable emulsifier e.g. an adduct of 8 to 12 moles of ethylene oxide with dodecyl alcohol or an adduct of 8 to 14 moles of ethylene oxide with nonylphenol or mixtures thereof, in an amount of about 10%, based on the reaction product, and then added in a manner known per se with water to a stable , dilutable, highly concentrated emulsion.
• the concentration of the stock emulsion should advantageously be 30 to 60%. A concentration of 45 to 50% is preferred.
• an acid preferably acetic acid.
• the polyorganosiloxane preparation to be used according to the invention be used with a hardener known per se, such as e.g. Dibutyltin dilaurate or zinc octoate, in amounts of 1 to 8% by weight, based on organopolysiloxane, to be added.
• a hardener known per se, such as e.g. Dibutyltin dilaurate or zinc octoate
• a first process variant is characterized in that the organosilicon compounds, preferably in the form of an aqueous dispersion, are added to the aqueous solution of the gelatinized starch before mixing with the finely divided coal.
• organosilicon compounds preferably in the form of an aqueous dispersion, are mixed with the finely divided coal.
• the briquettes obtained have a water absorption which is uniformly reduced over the entire cross section.
• the shaping of the briquettes, which takes place in a manner known per se by pressing, is not impaired by the addition of the organosilicon compounds.
• Another process variant for producing the briquettes according to the invention is characterized in that the shaped briquettes are sprayed with a solution of the organic compounds or the briquettes are immersed in such a solution.
• Fine coal briquettes in the production of which the organopolysiloxanes to be used according to the invention have been used, or which have been treated with these organopolysiloxanes after being deformed, have excellent storage and handling strength.
• the calorific value of the briquettes is not impaired and there are no annoying emissions caused by the binder when the briquettes are burned.
• starch-bound briquettes are prevented from being attacked by microorganisms and forming mold. The manufacturing process of the fine coal briquettes is not affected.
• a mixture of 1000 g (0.147 mol) of dihydroxydimethylpolysiloxane and 43.4 g of ⁇ -aminopropyltriethoxysilane is heated to 180 ° C. while stirring and passing nitrogen through and kept at this temperature until 13.5 g of ethanol have distilled off. The process takes about 4 hours. The resulting product is cooled.
• 1000 g of this product are mixed with 100 g of an emulsifier mixture of an ethoxylated triglyceride with an HLB value of 18 and an ethoxylated fatty alcohol polyglycol ether with an HLB value of 11 (ratio 60:40) and 900 g of water with an ultrasound device to form an emulsion given.
• the emulsion obtained contains 50% by weight of the organopolysiloxane to be used according to the invention.
• 100 g of anthracite coal are mixed with 10 g of water and 7.5 g of the starch slurry containing the polysiloxane (1. a) or 1. b)).
• the mass is mixed in a kneader until the water content has dropped to 5%.
• the mass has been heated to 95 ° C.
• Pillow-shaped briquettes are produced in a heated stamp press under a short pressure of 100 kp / cm2 and cooled at room temperature. After 3 days of storage in air, the water absorption is determined after 24 hours by pressurized water storage.
• briquettes are made.
• the briquettes obtained are immersed in a solution of the polysiloxane to be used according to the invention, diluted to 5% active ingredient.
• the solution contains 6% by weight, based on organopolysiloxane, of dibutyltin dilaurate.
• the impregnated briquettes thus obtained are air-dried for 3 days. After this, the water absorption is also determined by storing it under pressure after 24 hours.
• starch-bound briquettes are produced analogously to the state of the art, but no polysiloxane is used in their manufacture, and their water absorption is determined.
• the heat resistance of the four briquettes obtained is also determined.
• the heat resistance provides information about the stability of the briquettes in the fire. To determine the briquettes are 20 min in one Muffle furnace heated to 800 ° C and then loaded in a test press until it breaks.

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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)
• Compositions Of Macromolecular Compounds (AREA)
• Silicon Polymers (AREA)

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• 1988
  • 1988-10-29 DE DE3836940A patent/DE3836940C1/de not_active Expired - Lifetime
• 1989
  • 1989-10-17 DE DE8989119246T patent/DE58900703D1/de not_active Expired - Lifetime
  • 1989-10-17 EP EP89119246A patent/EP0368041B1/de not_active Expired - Lifetime

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