Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C11/00—Multi-cellular glass ; Porous or hollow glass or glass particles
  • C03C11/007—Foam glass, e.g. obtained by incorporating a blowing agent and heating
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B19/00—Other methods of shaping glass
  • C03B19/10—Forming beads
  • C03B19/108—Forming porous, sintered or foamed beads

Definitions

• the subject of the invention is a process for manufacturing expanded material in the form of granules from glass, in particular recovery glass. It also relates to the use of the granules obtained as constituents of parts intended for isolation, filtration, extraction of material.
• the object of the invention is to provide a process for manufacturing expanded materials in the form of granules, which is more efficient than those which already exist, in particular in terms of simplicity of implementation, profitability and quality of the product obtained.
• mixture of glass powder and aluminum nitride powder (AIN) with a binder being chosen from the group comprising hydrolysed vegetable gums, in particular hydrolysed gum arabic, starch, water, paraffin, natural gums,
• granulation of the mixture to obtain granules of size between 0.5 mm and 10 mm, and preferably between 1 mm and 8 mm, and more preferably still between 1 mm and 5 mm, and . baking the granules at a temperature between 700 and 1200 ° C, and preferably between 800 and 1100 ° C, and more preferably still close to 1000 ° C.
• the granules of expanded material according to the invention can be obtained from household recovery glasses.
• the composition of this household glass can vary significantly depending on its origins, such as the region, consumer habits or the collection season. This variation in the composition of the starting material is not without influence on the expansion.
• the method according to the invention has the advantage of being able to be implemented starting from inexpensive raw material, since it is recovery glass.
• the process is therefore necessarily economical in terms of raw material.
• Binders in various forms can be used. For example, one can use an arabic gum which is in the form of an unbroken whole gum. If necessary, other presentations of this product may also be suitable. The diversity of binders that can be used constitutes an additional advantage of the present invention.
• Aluminum nitride constitutes the blowing agent for the glass-based material according to the invention.
• the handling of this nitride is well controlled and relatively simple. In particular, its storage does not require any special precautions apart from its protection against humidity. This argues for the simplicity of the process according to the invention.
• glass powder is used having an average particle size of between 10 and 100 ⁇ m, and preferably close to 50 ⁇ .
• aluminum nitride powder having an average particle size smaller than that of the glass powder, and preferably an average particle size less than about 50 ⁇ m.
• the method according to the invention comprises a preliminary operation for manufacturing the binder, this operation comprising, in particular, the dissolution of a vegetable gum, in particular arabic gum, with water, the dissolution being carried out at a temperature between 20 and 150 ° C, and preferably between 20 and 100 ° C, for obtain a hydrolyzed gum used in the constitution of the binder.
• the binder can be obtained by maceration of gum arabic in a tank of hot water with constant stirring, the proportion possibly being around 3 kg of gum arabic per 130 liters of water. You can add about 500 to 1000 milliliters of pine essence. For that, it is advisable to mix the whole well during all the preparation. It is estimated that a good solution would be 2, 3 kg of gum arabic, 100 liters of water and 0.6 liters of pine oil.
• the binder thus prepared can be kept in tanks for a few days. It is helpful to shake the product before use.
• the introduction of pine essence has the effect of avoiding segregation of the gum. This introduction facilitates granulation since it lubricates the granules and helps in the calcination of gum arabic.
• the proportion of aluminum nitride powder used in the process according to the present invention determines the rate of expansion of the material obtained. This proportion can therefore, in principle, be adjusted as a function, in particular, of the density which it is desired to obtain for the expanded material.
• the aluminum nitride powder (AIN) is used in a relative proportion by weight of between 0.3 and 8%, preferably between 0.8 and 6%, and more preferably still between 1 and 4% of the total amount of glass powder.
• the decrease in the proportion of aluminum nitride powder requires increasing the temperature to obtain a substantially equal expansion rate.
• the granules obtained lose mechanical resistance, since cooking makes them brittle and fragile.
• the glass powder In practice, it is advisable, for example, to weigh the glass powder, then to put it in a mixer and to add to it the quantity of powder of corresponding aluminum nitride. At this stage, the whole can be mixed until a homogeneous mixture is obtained.
• the mixing time depends on the type of mixer used.
• the mixture thus prepared can be kept three to four days before use.
• a total quantity of glass powder and aluminum nitride powder is used relative to the binder corresponding to approximately 100 kg of glass powder and aluminum nitride powder for 5 to 30 liters of binder, and preferably for 10 to 25 liters of binder.
• More preferably 'again is previously mixed glass powder and the powder of aluminum nitride (AIN).
• the granulation is carried out using agglomeration presses or extruders, and preferably using a die pellet press.
• drums and the granulation trays By way of illustration, it is also possible to use the drums and the granulation trays.
• the granules are dried before subjecting them to cooking, in particular using an electric resistance drying system, an infrared drying system or a heat recovery drying system.
• the dried granules are, in addition, screened before being subjected to cooking, in order to essentially keep granules of size greater than approximately 0.5 mm, and preferably greater than approximately 1 mm.
• the granules are sprinkled using an inert powder chosen from the group comprising kaolin, silica, alumina and calcium carbonate or a mixture of these, before subjecting them to the cooking operation.
• an inert powder chosen from the group comprising kaolin, silica, alumina and calcium carbonate or a mixture of these, before subjecting them to the cooking operation.
• a rotary oven For cooking the granules, a rotary oven can be used, having a variable speed of rotation and comprising a system for adjusting the inclination of the reaction tube. Thanks to the combination of these two parameters, it is possible to control the passage time of the granules in the oven, which determines the cooking and the rate of expansion.
• the reaction tube as well as the granules can be covered with a release agent to avoid any agglomeration or any sticking. After recovery of the granules at the outlet of the tube, it is useful to carry out a simple operation, by blowing for example, to remove the excess of release agent entrained or found on the surface of the granules. The recovery of the granules does not require any particular precaution. If the cooling zone is respected, handling them does not present any risk.
• Screening and sizing operations can be envisaged at this level of the process if one wishes to carry out a distribution by size of the granules. These can be stored in barrels or other packaging without special precautions.
• aluminum nitride powder is used in a relative proportion by weight of between 0.5 and 5% relative to the total amount of glass powder, and preferably close by 2%, and cooking is carried out at a temperature between 750 and 1200 ° C, and preferably between 800 and 1100 ° C, for a time between 2 and 60 minutes, and preferably between 5 and 30 minutes, in order to obtain a material with open or closed porosity.
• addition is added of iron oxide (Fe 2 0 3 ), in a relative proportion by weight of between 0.5 and 6%, and of similar preference. 1.5%, based on the total amount of glass powder.
• the granules obtained in accordance with the process according to the invention can be used as constituents of parts intended for the extraction of materials, in particular filters, packing columns, as filling elements for insulation parts.
• the invention can be better understood with the aid of the nonlimiting examples which follow and which constitute preferred embodiments of the method according to the invention.
• 1 kg of powders comprising ground glass, 2% AlN, 2% Fe 2 0 3 and 200 milliliters of binder are mixed.
• Granulation is carried out using an endless screw granulator provided with a die of size between 1 and 5 millimeters.
• the agglomerates thus obtained are dried, then dusted with calcium carbonate.
• Cooking is carried out in a rotating oven at a temperature of approximately 1000 ° C.
• the granules are recovered. These have a size after expansion of between at least 3 and 10 millimeters. These granules have a closed porosity and have an apparent density of 180 to 220 kg / m 3 .
• the percentages used in this example are relative percentages by weight.
• the iron oxide Fe 2 0 3 has an influence on the quantity of pores formed during the process.
• Example 1 kg of ground glass is prepared with mud in the proportions of 75% glass and 25% mud. 2% by mass of aluminum nitride is added.
• the binder is incorporated in the same proportion as in Example 1.
• the granulation is carried out according to the same method as in Example 1. It is dusted with calcium carbonate after drying. Cooking is carried out in an oven rotating at
• the granules obtained measure 3 to 12 mm. They have an open porosity, their apparent density is between 160 to 220 kg / m 3 .
• the percentages used in this example are relative percentages by weight.
• oxides or metal salts can be added.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Manufacturing & Machinery (AREA)
• Glass Compositions (AREA)

Applications Claiming Priority (3)

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• 1997
  • 1997-01-17 FR FR9700463A patent/FR2758548B1/fr not_active Expired - Fee Related
• 1998
  • 1998-01-16 EP EP98903073A patent/EP0968140A1/de not_active Withdrawn
  • 1998-01-16 WO PCT/FR1998/000077 patent/WO1998031639A1/fr not_active Ceased

Non-Patent Citations (1)

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