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
  • C10L5/14—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders with organic binders
  • C10L5/16—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders with organic binders with bituminous binders, e.g. tar, pitch

Definitions

• the present invention relates to a binder which is suitable for the production of briquettes, to the use of this binder for the production of briquettes and to briquettes that are produced by using this binder.
• Briquettes mainly consist of a solid substance, such as a combustible, like for example coal or cokes, or minerals such as iron oxide, magnesium carbonate and the like, and of a binder therefor. They are widely used for domestic heating and for the purpose of a more efficient utilization of industrial raw materials. These briquettes are manufactured by pressing a mixture of the solid substance and the binder into the proper form under appropriate temperature and pressure conditions.
• Usual binders include for example coal tar pitch and bitumen, optionally in combination with sulphite liquor.
• a coal briquette on the one hand, should be able to gently glow under conditions where relatively little combustibles and oxygen are present, whereas under other conditions the briquette should be able to burn with a clear flame and not fall apart unburned. This may be expressed as fuel efficiency in terms of the coal content of the ashes.
• Another aspect of the burning behaviour is that a good fuel efficiency is required.
• the former aspect of the burning behaviour can also be viewed as a mechanical requirement for the binder, i.e. the binder should be able to confer to the briquette during burning enough strength that it will not fall apart until used up for the greater part.
• the (national) criteria regarding the the emission of environmentally objectionable substances should be met.
• the binder should also provide the briquette with so much strength and elasticity that the latter will not break to pieces under the usual transport and storage conditions. On the one hand, this is a matter of dynamical strength, meaning that during manufacturing, transport and the like the briquette may not break to pieces or that the majority, i.e. at least 95% of the briquettes does not break. Furthermore, the briquette should have a static strength during the complete usage cycle, which means that the lowermost briquette may not collapse under the weight of the briquettes lying on top thereof, neither during stacking nor at high temperatures.
• the selection of the binder is also determined by the sulfur content, the ash content and the emission of compounds during combustion or other processing.
• Smell is a criterion which is more subjective than the above-mentioned criteria. It has been found, for example, that the acceptance of coal briquettes for domestic use largely depends on the extent to which the binder and the briquette give off an undesirable smell under storage or usage conditions. Strongly smelling briquettes generally are not accepted. This is, of course, related to the fact that the briquettes are often stored in storage spaces which often are badly ventilated, such as in basements, and in the proximity of food such as potatoes or other personal effects.
• a conventional binder for coal briquettes is bitumen.
• Another type of coal briquette contains a special sulfite liquor (lignosulphonate) as binder, providing a so-called smokeless briquette.
• lignosulphonate lignosulphonate
• smokeless briquette These types of briquettes have a similar, but relatively high sulfur content of about 4.5 to 6% by weight.
• coal tar as binder, but mostly a bituminous binder is used because of its lower benzo(alpha)pyrene content.
• briquettes of solid substances A totally different application for briquettes of solid substances is for the production of silicon.
• silicon As described for example in British patents 2,150,128 and 2,088,840 silicon is produced from substantially pure silicon oxide, for example quartz sand, starting from briquettes containing on the one hand the silicon oxide and on the other hand a carbon source such as baking coal, cokes or bitumen.
• Such briquettes are then stacked in an electrical furnace and heated under pyrolysing conditions so that SiO2 is reduced to SiO, SiC and Si.
• a binder for use in this type of briquettes should fulfil a number of requirements different than for binders for coal briquettes.
• Binders for quartz briquettes should provide the briquette with a particularly good strength because often several tens of tons of briquettes are charged batchwise into a furnace.
• the binder should burn without producing a substantial amount of ashes, and more in particular, it should be free or virtually free of metals which may remain in the silicon and which are difficult or impossible to remove afterwards.
• binders having a low sulfur content are preferred, however, above all they should have good coke forming properties as is also the case for coal briquettes.
• briquette binders can also be used for briquettes of magnesium oxide or magnesium carbonate and briquettes of fly ash, generally metal-enriched dust.
• briquetting techniques are also used for the so-called partial briquetting, which means that low quality coals are briquetted with a relatively small proportion of binder, whereafter the briquettes are broken and subsequently mixed with quality coal or cokes for the production of metallurgic cokes grades.
• the binder which is suitable for the production of briquettes or shaped forms, comprises
• Component a) of the binder according to the invention comprises a hydrocarbon mixture containing a relatively large proportion of polyaromatics having a structure which is comparable to the structure of asphaltenes or pseudo-asphaltenes.
• Component a) usually has a C/H atomic ratio of 0.9 to 2.0, an aromaticity of 2.5 to 10 and a ring and ball softening point of at least 100°C.
• aromaticity shall mean the ratio of the number of aromatic carbon atoms relative to the number of aliphatic carbon atoms.
• the aromaticity is preferably from 2.5 to 5.
• Component a) is the by-product of the steam cracking of light hydrocarbons.
• light petroleum fractions such as LPG, gas oil or naphtha are cracked in a steam cracker, for example thermally or catalytically, preferably at a temperature of 700-2000°C, whereby the polyaromatic fraction is obtained after removal of the components which are volatile at atmospheric pressure, as the primary condensate from the product stream.
• This polyaromatic fraction is particularly suitable as first component of the binder according to the invention.
• This component, also called pyrolysis oil can be used as such for component a) in the binder of the invention or be processed in different ways to produce a modified polyaromatic fraction. In this way binders may be produced with a wide range of functional properties for a great number of different briquette compositions (applications).
• Component a) or the pyrolysis oil is preferably modified by subjecting it to one or more of the following treatments: extraction, distillation, flocculation/precipitation and oxidative treatment.
• One preferred way to modify the polyaromatic pyrolysis oil is to substantially remove the low molecular fraction from the oil to obtain a pyrolysis oil fraction with a more narrow molecular weight distribution which improves the adhesive strenght and affinity with respect to the fines that are to be briquetted.
• this concerns reducing the fraction having a molecular weight (determined by GPC in THF) smaller than 1000, so that a product remains having a ring and ball softening point of at least 100°C, preferably 110-170°C.
• the product has a molecular weight a distribution in which 95% by weight of the molecules have a molecular weight higher than 1000, and a weight averaged molecular weight of at least 1250, more preferably at least 2000.
• a binder based on a component a) modified this way is especially advantageous for producing magnesium carbonate or quartz briquettes.
• the molecular weight distribution of the pyrolysis oil may be controlled by means of extraction with appropriate extraction agents, such as Freon 113, dichloro methane, hexane, cyclohexane, isopropyl chloride, tert.butyl chloride, dichloro ethane, dichloro propane and the like.
• appropriate extraction agents such as Freon 113, dichloro methane, hexane, cyclohexane, isopropyl chloride, tert.butyl chloride, dichloro ethane, dichloro propane and the like.
• solvent oil solvent n-hexane 1 : 6.5 cyclohexane 1 : 7.7
• Freon-113 1 17 isopropyl chloride 1 : 18 tert.butyl chloride 1 : 2
• the temperature in this preparation varies generally from room temperature to the respective boiling point.
• distillation if required at decreased pressure, can be part of the process to remove the low molecular fraction until the desired composition of the remaining fraction is obtained.
• Appropriate conditions for this distillation include pressures of 5-50 mm Hg, at temperatures of 250-400°C, in order to remove 5-60% by weight of the starting pyrolysis oil material.
• a flocculation/precipitation technique for a rough separation of the pyrolysis oil component a) of the binder, thereby obtaining a separation in two phases.
• Possible chemicals for achieving this purpose are for instance mixtures of dichloro methane and methanol.
• the polyaromatic or pyrolysis oil component a) of the binder according to the invention can be subjected to an oxidative treatment, preferably in the presence of for example 0.1-3% by weight of a crystalline or amorphous alumina-silicate catalyst, for example a FCC-catalyst.
• an oxidative treatment preferably in the presence of for example 0.1-3% by weight of a crystalline or amorphous alumina-silicate catalyst, for example a FCC-catalyst.
• bitumen for example at least 10 minutes, as required 150-500 minutes, at a temperature of at least 200°C, yet preferably not higher than 360°C.
• the oxidative treatment has the advantage that one can remarkably increase the coke yield, particularly up to a value much higher than is usual for bitumen, while maintaining the desired strength of the briquette thus produced.
• coke yields up to 80% may be achieved, whereas bitumen has a coke yield of at the most 30%.
• the oxidation should, however, not be carried on too long, as in that case a product will be obtained which is too brittle, which is undesired with respect to strength properties.
• the second component b) of the binder according to the invention comprises at least one component chosen from the group consisting of atmospheric and vacuum residues and distillates obtained in the refining and/or (hydro)cracking of petroleum or petroleum fractions.
• This component b) which itself may be a mixture of two or more of the above-mentioned residues and distillates serves to improve the processibility of the binder, but also to affect the properties of the briquettes.
• component b) of the binder comprises at least a vacuum residue of the refining and/or (hydro)cracking of petroleum cg. petroleum fractions.
• the advantage hereof is that a certain degree of plasticity is introduced, which enhances the dynamic strength properties of the binder.
• At least 10% by weight of the vacuum residue is present, based on the binder. If, for example, a certain residue from this group is used for reasons of processibility then it may be necessary to use also a certain distillate from this group in order to improve the miscibility and compatibility of the several binder components a) and b).
• a useful composition for component b) of the binder contains 40-100% by weight of a vacuum residue of the petroleum refining and 60-0% by weight of a vacuum distillate of the petroleum refining.
• the vacuum residue in component b) preferably contains a boiling hexane insolubles content of at least 20%. Preferably it also has a sulfur content not higher than 1.0% by weight, especially in the case when the binder is intended for use in coal briquettes. For the use for other briquettes the sulfur content is also of importance when during their use there can be some emission of objectionable substances in view of national regulations regarding environmental protection.
• the vacuum residue in component b) has a somewhat more paraffinic character than component a) of the binder according to the invention. This relatively higher paraffinic character is expressed in the C/H ratio in the vacuum residue, which is preferably between 0.7 and 1.0 (on atomic basis).
• an elasticity improving agent such as atactic polypropylene or polyethylene wax
• an elasticity improving agent such as atactic polypropylene or polyethylene wax
• component b) may also advantageously contain a further fraction serving to improve the miscibility and compatibility of the other components.
• a distillate for example a vacuum distillate of the refining and/or hydrocracking of petroleum, cq. petroleum fractions.
• a mineral oil or a heavy gas oil having an initial boiling point of preferably 260°C or higher and more preferably between 365 and 500°C at atmospheric pressure.
• the binder consists of 75-95 parts by weight of polyaromatic component a) and 5-25 parts by weight of component b) and optional other additives.
• the binder is preferably substantially free of ashes, minerals, metals and in particular free of elements of the group IIIA and VA of the Periodic System of Elements, or compounds thereof.
• substantially free is meant that the content of the respective component is not higher than 0.05% by weight, based on the binder.
• the binder according to the invention can be prepared in different ways, however, it should always be taken into account that the binder generally will have a softening point around 100°C, more particularly between 80 and 150°C.
• the binder should be prepared at a temperature which is clearly above its softening point in order to avoid problems regarding solidification or a too high viscosity.
• the components can be supplied to a blender heated at 250°C in which the components are mixed to obtain a homogeneous mass at this temperature.
• the binder thus obtained, to which optionally also an amount of lime is added, may be stored, transported and processed at this temperature.
• the binder according to the invention has an excellent homogeneity and stability. More particularly, the binder fulfils the requirements of Dutch standard NEN 3965, which means, among other things, that no phase separation takes place during storage.
• the invention further relates to the use of the binder as described above for the production of briquettes.
• This briquetting may be carried out in the usual way with the binder according to the invention and the solid substance to be bound.
• it is referred to the methods which are usual in this area of technique, for example Perry (Chemical Engineers Handbook, 3rd Edition, page 1564).
• the invention also relates to a briquette comprising a binder according to the invention and a bound component.
• This bound component may consist of a conventional solid combustible, such as coal or cokes, but also of a starting material for another reaction, such as magnesium oxide, magnesium carbonate or quartz sand.
• the substance to be bound may also consist of a product which should be brought into the form of a briquette, whether or not temporary, for storage. For this purpose one can think of fly ash or radioactive waste.
• the binder content in the briquette is chosen such that optimal results are achieved. These binder contents may vary between 1 and 15% by weight, based on the weight of the briquette. For the production of coal briquettes for combustion purposes this content will generally be about 8% by weight.
• the binder content is also determined by the desired carbon/cokes-content of the briquette. It may be remarkably higher than the 15% by weight mentioned.
• the binder content may be less than 8% by weight, because for this application homogeneity is more emphasized than the briquette strength. Binder contents of 2-5% by weight are thereby possible.
• the main component of the binder was prepared by means of precipitation/flocculation.
• This product was mixed at 175°C with 15% by weight (based on the total binder) of a mixture (1/1) of vacuum residue and vacuum distillate.
• the resulting binder was used in an amount of 6% by weight for the production of magnesium carbonate briquettes.
• the green briquettes were shown to have a satisfactory strength.
• the "heat" strength was satisfactory as well.
• the static compression strength was at least 250 kg/cm2, which is amply sufficient for magnesium carbonate briquettes.
• coal briquettes were produced from anthracite fines and 8%, based on the briquette weight, of a binder according to the invention.
• the binder contained 86% by weight of a pyrolysis oil fraction, 8% by weight of vacuum residue and 6% by weight of vacuum distillate and had a sulfur content of 0.33% by weight, an ashes content of 0.11% by weight, a softening point of 88°C (ring and ball).
• the briquettes had a static strength of 133 kg, a dynamic strength of 91.3% and an emission of 265 ppm SO2 in the flue gass.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Geology (AREA)
• Environmental & Geological Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Organic Chemistry (AREA)
• Solid Fuels And Fuel-Associated Substances (AREA)
• Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
• Dental Preparations (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Working-Up Tar And Pitch (AREA)

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Citations (5)

• 1989
  • 1989-04-14 DE DE8989200939T patent/DE68903352T2/de not_active Expired - Fee Related
  • 1989-04-14 ES ES198989200939T patent/ES2036022T3/es not_active Expired - Lifetime
  • 1989-04-14 EP EP89200939A patent/EP0337579B1/de not_active Expired - Lifetime
  • 1989-04-14 AT AT89200939T patent/ATE82019T1/de not_active IP Right Cessation

Patent Citations (5)

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