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
  • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
  • C03C1/004—Refining agents
• • 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
  • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
  • C03C1/002—Use of waste materials, e.g. slags

Definitions

• the invention relates to the melting of glass, in particular of fiber-transformable glass, in the presence of sulphide as a foaming reducing agent.
• Sulfate is commonly used as a melting agent for silica in the process of melting glass. Sulphate facilitates the melting of silica and reduces the proportion of unmelted silica grains in the final glass, called "unmelted".
• an alkaline oxide such as Na 2 O (in silicosodium-calcium glasses) makes the sulfate soluble in the melted composition. As a result, this sulfate decomposes moderately (low SO3 production) during the smelting process.
• a vitrifiable composition comprising 0.6% by weight of initial sulphate can result in a glass finally containing 0.3% by weight of residual sulphate.
• alkaline oxide Some applications, such as some electronic components, are incompatible with the presence of alkaline oxide in the glass. In particular, standards require less than 2% by weight of alkaline oxide.
• the manufacture of a silicosodocalcic glass does not give rise to any foaming by decomposition of the sulphate above 1300 ° C. It has already been proposed to use a mixture of sulphate and sulphide as a silicosodocalcic glass refining agent.
• the refining agent is used to increase the volume of the bubbles produced during the melting to increase them faster, without creating new ones. Part of the gaseous SO2 used to swell the bubbles to be removed is emitted during the fusion phase by reaction between the sulphate and the silica, the sulphide acting as an accelerator of this reaction.
• the refining is important for the silicosodocalcic glass which is then transformed into flat or hollow glass.
• Glasses intended for fiberizing are not particularly refined and the manufacturing furnaces are not followed by refining compartment.
• a poor quality of refining of the glass can cause the breakage of the filaments, in particular fine filaments.
• the recipe usually followed by the glassmakers is to incorporate into the vitrifiable mixture a mixture of sulphate and a reducing element such as carbon.
• the refining quality required for fiber glass is less than that of a flat glass.
• This sulphate of alkali or alkaline earth also plays the role of flux.
• a film of foam is formed on the surface of the bath.
• This foam is a real insulator that curbs heat exchange between overhead burners and glass.
• the power of the air burners can not be increased enormously because the thermal limit of the furnace structure (refractory degradation temperature) is quickly reached.
• the presence of foam makes it necessary to compensate for the lack of heat transfer from the air burners to the glass bath by increasing the heating power supplied in the bath itself, under the foam, for example by means of electrodes embedded in the liquid glass.
• electric heating even if its efficiency is excellent, is very expensive compared to heating by combustion of fossil material, for a given amount of energy transmitted to the glass.
• the invention therefore relates to a process for manufacturing a glass, especially intended to be fiber, by melting vitrifiable materials at more than 1300 ° C. comprising silica and an alkali or alkaline earth sulfate, characterized in that a sulphide is added to the vitrifiable materials in order to reduce the formation of foam (which can be measured by its height) at more than 1300 ° C.
• the invention relates to glasses which foam at more than 1300 ° C. by decomposition of the sulfate so that a fusion method identical to that of the invention but without the addition of sulfide leads to a higher foam height than that obtained with the method according to the invention.
• the sulphide is that of a metal such as Na, Ca, Zn, Mo, Cd.
• the sulphide can therefore be chosen from the following sulphides: Na 2 S, CaS, ZnS, MoS 2, CdS.
• the sulfide can be a mixture of several metal sulfides.
• the addition of sulphide to vitrifiable materials may be accompanied by the addition of other materials, provided that these other materials are compatible with the process of melting and the composition of the final glass. It turns out that slags from blast furnaces in steelmaking can be very suitable materials for glass and can also be an interesting source of sulphide.
• a slag is from the outset a partially vitrified material, generally containing oxides such as CaO, Al 2 O 3, SiO 2 and MgO and melting quite easily, which is advantageous.
• the sulphide can be introduced into vitrifiable materials in the form of slag.
• a standard composition of slag is for example:
• the introduction of the sulphide in the form of slag generally provides an energetic gain to fuse the glass, said gain coming mainly from the heating of the gases. Indeed, the slag causes very little fire loss by nature. The slag also gains heat of reaction because it is partially vitrified.
• the material added to the vitrifiable mixture as a sulphide source preferably has a fairly fine particle size and is preferably preferably free of particles larger than 400 ⁇ m and even free of particles larger than 300 ⁇ m and even so preferred free from particles larger than 200 ⁇ m.
• the reactivity of the sulphide with the sulphate of the vitrifiable mixture is indeed related to its particle size.
• the sulphide should be free of large refractory grains (such as silicon carbide, corundum ...), grains that melt with difficulty during the fusion and therefore are sources of breakages in fiber drawing.
• the amount of sulphide provided is sufficient so that the height of the foam is significantly reduced, or even completely eliminated, compared to the same melting process without the addition of sulphide.
• the person skilled in the art is in the habit of expressing the amounts of sulphate or sulphide in SO3 equivalent by weight or by mol. This is the amount of SO2 (or initial SO3 equivalent) that can be generated by the compound after oxidation.
• SO2 or initial SO3 equivalent
• one mole of Na2S equals one mole of SO3 because the oxidation of one mole of Na2S leads to the formation of one mole of SO 2 (Na 2 S + 3/2 O 2 -> SO 2 + Na 2 O).
• one mole of MoS 2 corresponds to two moles of SO3.
• the amount of sulphide expressed as SO3 is generally less than 50%, and preferably less than 30% and generally less than 25% of the amount of alkali or alkaline earth sulphate, in particular Na 2 SO 4 or CaSO 4 , expressed as SO3 (in mole or in weight, it is the same here).
• the amount of sulfide expressed as SO3 is generally greater than 5%, and preferably greater than 10% by mole of the amount of alkali or alkaline earth metal sulfate expressed as SO3.
• the alkali or alkaline earth sulphate may be sodium sulphate or calcium sulphate.
• the amount of alkali or alkaline earth sulphate added to batch materials is generally greater than 0.03% (expressed as SO3 weight) of the total final glass mass and is generally less than 1.2% (expressed as by weight of SO3) of the total mass of final glass. This amount is generally from 0.1 to 1, 2 and preferably from 0.2 to 1% (expressed by weight of SO 3) of the total mass of final glass.
• the glass in particular the glass E within the meaning of the standard, C or SD 578: 2000 in melt concerned by the present invention forms above 1300 ° C. a foam with a height of minus 1, 2 cm, see at least 2 cm, even at least 3 cm, or even at least 5 cm.
• the presence of the sulphide makes it possible to reduce this height by at least 10%, or even by at least 20%, or even by at least 30%.
• a foam is an agglomeration of gas bubbles separated by a thin wall of liquid whose thickness is much smaller than the diameter of the bubbles. Maximum foam heights were compared, since during a batch melting process, the foam height may vary.
• the glasses concerned by the present invention are those giving rise to an important formation of foam by decomposition of alkali or alkaline-earth metal sulphate at more than 1300 ° C. during the melting process.
• it may be E glass within the meaning of ASTM D 578: 2000, glass AR (that is to say resistant to alkalis) according to DIN 1259-1, glass C at meaning of D578: 2000 and S-glass within the meaning of D578: 2000.
• All these glasses are silicate glasses with a silica content generally less than 70% by weight and more generally less than 69% by weight. They are fibrable by the known means when they are passed through orifices (extrusion through dies, extrusion / drawing by rotating fiber plates, etc.). In particular, they can be converted into fiber directly after melting and without a refining compartment between the melting furnace and the fiberizing device.
• the invention also relates to a process for the continuous preparation of glass fibers comprising the melting of said glass in a melting furnace by the melting method according to the invention, then the transformation into fiber of said glass in a fiber-drawing device, without solidification of the glass between the oven and the fiberizing device.
• this process requires no refining compartment between the oven and the fiberizing device.
• a 0.4 m 2 furnace is available for melting vitrifiable materials. This oven is equipped with 8 oxgen / fuel gas burners providing a total of 90 to 130 kW and 2 zones of electric boosting bringing a total of 12 kW.
• Table 1 indicates the vitrifiable materials introduced into the oven to finally obtain 100 kg of glass. The quantities introduced exceed 100 kg because of the gas flows.
• alkaline oxide Na 2 O + K 2 O + Li 2 O
• Example 1 The tests were carried out at a constant rate of 15 kg / hour, at constant vault temperature (1580 ° C.), and at constant hearth temperature (1350 ° C. in the middle of the oven). From Example 1 to Example 4, the sulphide content was increased and the energetic control of the power of the burners and electric powers was adjusted to keep the vault and hearth temperatures constant. The power of the overhead burners was first set to maintain the constant vault temperature, and then the electrical power was adjusted to the desired hearth temperature.
• Table 3 gives the energy gain calculated on the heat of manufacture of the glass by introducing slag taking into account the heat of melting slag.

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=37733703

Family Applications (1)

Country Status (4)

Families Citing this family (4)

Family Cites Families (6)

• 2006
  • 2006-09-07 FR FR0653616A patent/FR2905693B1/fr not_active Expired - Fee Related
• 2007
  • 2007-09-03 WO PCT/FR2007/051866 patent/WO2008029054A2/fr active Application Filing
  • 2007-09-03 EP EP07823763A patent/EP2059486A2/de not_active Withdrawn
  • 2007-09-03 US US12/439,930 patent/US20090277227A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events