NZ627176B2 - Method for drawing vitrifiable materials - Google Patents
Method for drawing vitrifiable materials Download PDFInfo
- Publication number
- NZ627176B2 NZ627176B2 NZ627176A NZ62717612A NZ627176B2 NZ 627176 B2 NZ627176 B2 NZ 627176B2 NZ 627176 A NZ627176 A NZ 627176A NZ 62717612 A NZ62717612 A NZ 62717612A NZ 627176 B2 NZ627176 B2 NZ 627176B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- furnace
- molten
- vitrifiable material
- molten vitrifiable
- dam
- Prior art date
Links
- 239000000463 material Substances 0.000 title claims abstract description 110
- 238000000034 method Methods 0.000 claims abstract description 34
- 238000009826 distribution Methods 0.000 claims abstract description 27
- 239000002994 raw material Substances 0.000 claims abstract description 20
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 11
- 239000012530 fluid Substances 0.000 claims abstract description 8
- 230000001131 transforming Effects 0.000 claims abstract description 8
- 239000000835 fiber Substances 0.000 claims description 29
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 16
- 229910000460 iron oxide Inorganic materials 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 8
- PNEYBMLMFCGWSK-UHFFFAOYSA-N AI2O3 Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 7
- 230000004927 fusion Effects 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 239000011733 molybdenum Substances 0.000 claims description 5
- 239000002557 mineral fiber Substances 0.000 claims description 3
- 238000004031 devitrification Methods 0.000 claims description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 abstract description 2
- 238000002844 melting Methods 0.000 abstract description 2
- 239000011707 mineral Substances 0.000 abstract description 2
- 239000002826 coolant Substances 0.000 abstract 2
- 239000011521 glass Substances 0.000 description 13
- 235000013980 iron oxide Nutrition 0.000 description 7
- 238000011049 filling Methods 0.000 description 6
- 239000011819 refractory material Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 4
- 230000001105 regulatory Effects 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium monoxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N TiO Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 241000826860 Trapezium Species 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000002493 climbing Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000002349 favourable Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001737 promoting Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000000475 sunscreen Effects 0.000 description 1
- 239000000516 sunscreening agent Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/04—Manufacture of glass fibres or filaments by using centrifugal force, e.g. spinning through radial orifices; Construction of the spinner cups therefor
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/02—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating
- C03B5/027—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating by passing an electric current between electrodes immersed in the glass bath, i.e. by direct resistance heating
- C03B5/03—Tank furnaces
- C03B5/031—Cold top tank furnaces
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/167—Means for preventing damage to equipment, e.g. by molten glass, hot gases, batches
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/20—Bridges, shoes, throats, or other devices for withholding dirt, foam, or batch
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/20—Bridges, shoes, throats, or other devices for withholding dirt, foam, or batch
- C03B5/205—Mechanical means for skimming or scraping the melt surface
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/26—Outlets, e.g. drains, siphons; Overflows, e.g. for supplying the float tank, tweels
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/26—Outlets, e.g. drains, siphons; Overflows, e.g. for supplying the float tank, tweels
- C03B5/265—Overflows; Lips; Tweels
Abstract
process for producing mineral fibres is disclosed. The process comprises inserting raw materials (4) into a rotary furnace (1) with electrodes (9), then melting the raw materials (4) in the furnace (1) to form a molten vitrifiable material (8), then the outflow of the molten vitrifiable material (8) from the furnace to a distribution channel (11), then the outflow of the molten vitrifiable material (8) via a hole (12) in the bottom of the distribution channel to supply a drawing device, then transforming the molten vitrifiable material (8) into fibres by means of the drawing device. The flow of the molten vitrifiable material (8) between the furnace (1) and the distribution channel (11) passes below a height-adjustable metal barrier (10) having a casing cooled by a flow of coolant fluid. Adjusting the height of the barrier (10) affects the temperature of the molten vitrifiable material (8) in order to bring it into the viscosity range required for drawing into fibres. 8) from the furnace to a distribution channel (11), then the outflow of the molten vitrifiable material (8) via a hole (12) in the bottom of the distribution channel to supply a drawing device, then transforming the molten vitrifiable material (8) into fibres by means of the drawing device. The flow of the molten vitrifiable material (8) between the furnace (1) and the distribution channel (11) passes below a height-adjustable metal barrier (10) having a casing cooled by a flow of coolant fluid. Adjusting the height of the barrier (10) affects the temperature of the molten vitrifiable material (8) in order to bring it into the viscosity range required for drawing into fibres.
Description
METHOD FOR DRAWING VITRIFIABLE MATERIALS
The invention relates to a process of fabrication of mineral fibers
comprising the fusion of vitrifiable materials in a circular furnace with electrodes,
the supply of a distribution channel with these molten materials, then their
transformation into fibers.
The furnace used in the framework of the invention is known as a cold-
top furnace allowing vitrifiable materials to be molten by the heat
generated by resistive heating using electrodes immersed in the vitrifiable
materials. The solid charge of vitrifiable materials is carried by the top and forms
an upper layer completely covering the bath of molten materials. According to
the prior art, the molten materials are extracted by the furnace bottom or
laterally via a spout and are fed into a distribution channel supplying fiber
forming devices. The fiber forming is a continuous process directly after the
fusion of the vitrifiable materials. When a spout is used between the furnace
and the distribution channel, rapid wearing of the refractory materials forming
the spout is observed, in particular the upper part of the latter. Indeed, in spite
of the use of cooling systems allowing the attack of the refractory materials by
the molten materials at high temperature to be limited, these refractory
materials must generally be replaced sooner than the other elements made of
refractory materials of the furnace. Such a replacement furthermore requires the
shutdown of the furnace. Moreover, a simple spout is neither a means for
regulating the flow nor a means for regulating the temperature of the molten
material. The temperature of the molten material is indeed an essential
parameter for obtaining a high quality fiber forming process. The correct
temperature of molten material in the fiber forming process is first of all obtained
by adjusting the electrical current delivered by the electrodes. The design of the
distribution channel such as its length, its thermal insulation and its specific
heating means also have an influence on this temperature. The regulation of the
whole fiber forming process is particularly difficult and may require a long period
of trial and error. This difficulty is all the greater as this type of furnace generally
operates for relatively short-lived fabrication campaigns and the transition times
(period for stabilization of the fabrication from the start) are therefore long
compared to the operation time in continuous mode. This type of fabrication
generally operates with outputs in the range between 5 and 100 tons per day. It
is the passage of the glass in the fiber forming dies which limits the output. The
transformation into fibers is therefore the determining step for the flow of glass
through the whole process (output). This is why the height of the dam only
regulates the temperature and not the flow. This type of furnace with relatively
modest dimensions (oven bottom internal surface area in the range between 1
m² and 30 m²) is very flexible and can be easily stopped at any time depending
on the circumstances. It can generally operate without stopping for between 24
hours and 6 months, or even longer.
US6314760 discloses a circular furnace with electrodes and a conical
furnace base supplying a distribution channel, the flow of glass between the
furnace and the canal going through a molybdenum tube surrounded by an
envelope through which cooling water flows. This document does not offer any
solution for regulating the flow of glass and the temperature of the glass exiting
from the furnace.
US3912488 discloses a circular furnace with electrodes and a conical
furnace base comprising an orifice for extraction of the molten materials from
the apex of the cone of the furnace base, said orifice being cooled by a
circulation of water.
The invention contributes to overcoming the aforementioned problems by
offering an additional possibility of regulating the temperature of the molten
vitrifiable material. It has indeed been observed that, in this type of circular
furnace, a vertical temperature gradient existed in the vitrifiable materials, the
hotter materials being at the top just under the crust of vitrifiable materials not
yet molten, and the nearer to the furnace bottom, the cooler they are. It has also
been observed that it was possible to act on the temperature of the flow of
molten materials going from the furnace to the distribution channel by using the
depth of a vertically mobile dam situated laterally with respect to the furnace,
between the furnace and the distribution channel. The lower the dam, the lower
is the temperature of the molten materials passing under it, and vice versa.
Thus, the invention relates to a process of fabrication of mineral fibers
comprising the introduction of raw materials into a circular furnace with
electrodes, then the fusion of the raw materials in said furnace in order to form a
molten vitrifiable material, then the outflow of the molten vitrifiable material in
the furnace via a lateral outlet from the furnace so as to supply a distribution
channel, then the outflow of the molten vitrifiable material via an orifice on the
furnace bottom of the distribution channel so as to supply a fiber forming device,
then the transformation into fibers of the molten vitrifiable material by said fiber
forming device, the flow of molten vitrifiable material between the furnace and
the distribution channel passing under a metal dam being adjustable in height
comprising an envelope cooled by a flow of cooling fluid.
The vertical temperature gradient in the molten materials in the furnace
will be higher the more readily that the vitrifiable materials absorb infrared
radiation. The presence of iron oxide in the molten charge contributes to the
absorption in the infrared. Thus, the process according to the invention is
particularly well suited when the molten material contains more than 2% by
weight of iron oxide (sum of all the forms of iron oxide) and even more than 3%
and even more than 4% by weight of iron oxide. Generally speaking, the molten
material contains less than 20% by weight of iron oxide. The process according
to the invention is notably well suited when the molten material comprises from
1 to 30% by weight of alumina, and even 15 to 30% by weight of alumina. For
example, it may be used to melt glasses for fibers with compositions described
in one or other of the documents WO99/57073, WO99/56525, WO00/17117,
WO2005/033032, WO2006/103376, incorporated here by reference.
The ideal temperature for fiber forming depends on the composition of
the molten material. Generally speaking, the idea is for its viscosity to be in the
range between 25 Pa.s and 120 Pa.s. Thus, according to the invention, the
height of the dam can be adjusted such that the viscosity of the molten vitrifiable
material is included within this range. Indeed, the height of the dam has a direct
influence on the temperature of the vitrifiable material and hence on its
viscosity. The height of the dam is therefore determined (in other words
adjusted) such that the viscosity of the molten vitrifiable material is in the range
between 25 Pa.s and 120 Pa.s in the fiber forming device.
The invention is suited to the forming of fibers from glass or from rock.
The temperature of the molten vitrifiable material passing under the dam
is chosen as being higher than the devitrification temperature of the vitrifiable
material. Generally speaking, the temperature of the vitrifiable material passing
under the dam is in the range between 850 and 1700°C. For a vitrifiable
material comprising at least 15% by weight of alumina, notably 15 to 30% of
alumina, the temperature of the vitrifiable material passing under the dam is
generally in the range between 1200 and 1700°C. The height of the dam is
therefore adjusted such that the molten material passing under it is in the
correct range of temperature. The dam according to the invention therefore
allows a true regulation of the process according to the invention.
The invention is suited to all types of glass or rock. However, the more
readily the vitrifiable material absorbs infrared radiation (IR), the more
advantageous the invention. Indeed, the greater the absorption of IR by the
vitrifiable material, the more heat transfers are limited and the greater the
thermal gradient observed from the furnace bottom to the crust of raw materials
floating on top of the molten vitrifiable material. The furnace bottom is thus
colder the more the vitrifiable material absorbs IR. This is favorable to the total
lifetime of the furnace bottom. A vitrifiable material absorbing less IR is for
example a glass of the borosilicate type. A glass absorbing more IR is for
example an automobile glass used as a sun screen in sun roof applications.
The dam is made of metal and is hollow such that a cooling fluid can flow
through its interior. The dam can be constructed from metal plates that are
welded together. Advantageously, the welds are inside the dam. The metal of
the dam can be steel such as AISI 304. The immersed part of the dam can be
totally made from such a steel. Conduits are connected via the top of the dam to
allow the entry and the exit of the cooling fluid. Advantageously, the cooling fluid
is liquid water in the form of running water whose temperature prior to passage
in the dam is generally in the range between 5 and 50°C, preferably between 20
and 40°C (water that is too cold with a temperature below 10° would risk
causing condensation of water onto the installation). The cooling fluid could be
air. The dam generally has a height that is sufficient to potentially completely
block the flow of molten materials between the furnace and the distribution
channel. Advantageously, the cross section of the dam has a trapezoidal shape,
in other words its two large faces can come closer toward the bottom. It is thus
easier to retract the dam if the latter is trapped in solidified vitrifiable material.
The width of the dam substantially corresponds to the width of the passage for
the molten charge flowing toward the distribution channel, which substantially
corresponds to the width of the distribution channel. The width of the passage
for the molten vitrifiable material under the dam and of the dam itself is
generally in the range between 20 and 60 cm (width measured transverse to the
direction of flow of the vitrifiable material).
The furnace is circular. The bottom of the furnace may be flat or may
comprise an inclined surface. The inclined surface of the furnace bottom allows
the molten vitrifiable material to run toward the lowest point of the furnace
bottom as it begins to melt. Indeed, it is advantageous to bring together the
small volume of molten vitrifiable material at the start of the filling of the furnace
in order to form a hot spot accumulating the heat. This allows the process to be
instigated faster at the start of filling and has the effect of priming the operation
of the furnace. The inclined surface may be that of an upside down cone whose
apex is the lowest point of the bottom of the furnace. It may also take the form
of an inclined plan whose intersection with the cylindrical wall of the furnace
forms a curved line, which has a lowest point of the furnace bottom. Other
shapes are possible, the idea being that the furnace bottom comprises a
concave angle oriented upward toward which the molten vitrifiable material runs
at the start of the filling of the furnace so as to accumulate. This angle can be
formed where the furnace bottom and the side wall of the furnace meet. The
raw materials are therefore preferably directed toward this angle at least at the
start of the filling of the furnace. If this angle is not in a central position in the
furnace bottom, initially, the solid raw materials may be channeled toward this
angle, then when a sufficient level of molten vitrifiable material is reached, the
solid raw materials are channeled more over the center of the furnace bottom.
The solid raw materials may also be directed toward this concave angle of the
furnace bottom when it is desired to put the furnace into standby (stoppage of
the output, no supply with charge and keeping the furnace hot). Preferably, the
electrodes are near to the place where the raw materials are introduced. Thus,
if the latter are able to be introduced successively at several locations, it will be
advantageous to be able to move the electrodes in order to make them follow
the location of introduction of the raw materials.
The interior of the furnace is lined with refractory materials coming into
contact with the vitrifiable materials, both on the furnace bottom and on the side
wall. The side wall generally comprises an external metal envelope in contact
with the ambient air. In general, this metal envelope comprises two partitions
between which cooling water flows (system not shown in the figures).
Electrodes are immersed in the vitrifiable materials from the top. These
electrodes generally comprise a part made of molybdenum immersed in the
vitrifiable materials and a part made of steel above the vitrifiable materials
connected to an electrical voltage. Thus, the part of the electrodes in contact
with the vitrifiable materials is generally made of molybdenum. It would seem
that electrodes made of molybdenum progressively react with the iron oxide
present in the vitrifiable materials promoting the presence of FeO to the
detriment of Fe O , said FeO absorbing IR in particular, which goes in the
direction of an increase in the temperature gradient from the furnace bottom to
underneath the crust of raw materials. The introduction of the electrodes from
above has several advantages with respect to the configuration according to
which the electrodes would go through the furnace bottom. Indeed, the passage
through the furnace bottom would require the formation of electrode blocks
making the link between the electrode and the furnace bottom, which blocks are
particularly difficult to produce due to the fact that the furnace bottom is also
cooled by a metal envelope. An electrode in the furnace constitutes a hotter
region and the electrode blocks made of ceramic refractory material would be
corroded particularly rapidly. In addition, immersing the electrodes from the top
favors the creation of a temperature gradient climbing from the bottom to the
top, owing to the fact that the electrodes heat at the top, combined in addition
with the formation of FeO preferentially around the electrodes, hence also at the
top. The number of electrodes is adapted according to the size and to the
output of the furnace. The furnace is not generally equipped with means for
stirring the vitrifiable materials (no mechanical stirrer nor immersed burner)
except potentially of the bubbler type. The furnace is equipped with means for
introduction of the vitrifiable materials. These are generally in powder form, or in
granulated form, generally up to a diameter of 10 mm. The vitrifiable materials
are distributed uniformly over the whole inside surface of the furnace in order to
form a crust covering the molten materials. As a means of introduction of the
vitrifiable materials, a cone rotating above the inside surface of the furnace may
be used. The vitrifiable materials are made to fall onto the rotating cone whose
rotation projects them uniformly over the whole inside surface of the furnace.
The vitrifiable materials not yet molten form a crust on the surface above the
molten vitrifiable materials. This crust forms a thermal screen limiting the heat
losses from the top. Thanks to this, the top of the furnace can be simply made
of boiler steel, without any particular means of cooling. The inside surface area
of the furnace is generally in the range between 1 and 25 m². In operation, the
depth of vitrifiable materials (molten + non-molten) is generally in the range
between 20 and 60 cm. The output in molten vitrifiable materials can generally
be in the range between 5 and 100 tons per day.
The distribution channel comprises at least one orifice in its furnace
bottom. It may comprise 2 or 3 or more of them depending on the number of
fiber forming devices to be simultaneously supplied. The thread of molten
vitrifiable materials falling through this orifice is subsequently oriented toward a
fiber forming machine.
The transformation into fibers can be carried out by a device known as
an internal centrifugation device. The principle of the method of internal
centrifugation is itself well known to those skilled in the art. Schematically, this
method consists in introducing a thread of molten mineral material into a
centrifuge, also referred to as fiber forming plate, rotating at high speed and
having around its periphery a very large number of orifices via which the molten
material is projected in the form of filaments under the effect of the centrifugal
force. These filaments are then subjected to the action of an annular extrusion
current at a high temperature and speed running along the wall of the
centrifuge, which current thins it and transforms it into fibers. The fibers formed
are driven by this gaseous extrusion current toward a receiving device generally
formed by a strip being permeable to gas. This known method has been the
subject of many improvements, notably those disclosed in the European patent
applications N° EP0189534, EP0519797 or EP1087912.
Figure 1 shows the elements allowing the process according to the
invention to operate in continuous mode from the fusion up to the fiber forming.
A circular furnace 1 comprising a furnace bottom 2 comprising an inclined
surface and a side wall 15 of the cylindrical type is supplied with vitrifiable
materials 4 falling onto a metal cone 5 rotating about a vertical axis 6. This
rotation allows the vitrifiable materials to be distributed over a larger surface
area around the central axis 6. The inclined surface is part of a cone whose
apex 3 is turned downward, forming a concave angle turned upward. The
vitrifiable materials not yet molten form a crust 7 on the surface before melting
and supplying the bath 8 of molten materials. The electrodes 9 produce the
calories required for the fusion of the vitrifiable materials. The molten materials
leave the furnace 1 by passing under the dam 10 with adjustable height and are
cooled by a circulation of water. They subsequently arrive in the distribution
channel 11 having orifices 12 (a single orifice is shown, where other orifices
may be present further along to the right of the channel). They flow through the
orifices 12 so as to form a thread 14 and fall into a trough 13 so as to
subsequently supply a fiber forming device not shown. The dam 10 has a
trapezoidal cross section (trapezium parallel to the plane of the figure which can
be seen in the latter), in other words its largest sides 16 and 17 come closer
toward the bottom.
Figure 2 shows the elements allowing the process according to the
invention to operate in continuous mode from the fusion up to the fiber forming.
All the same elements as in figure 1 are seen except that the furnace bottom 2
here takes the form of an inclined plane. The intersection of this furnace bottom
2 with the cylindrical wall 15 forms a curved intersection comprising a lowest
point 23. The meeting point of the furnace bottom and of the side wall forms, at
this lowest point, an angle being concave upward capable of receiving the
molten vitrifiable material. A by-pass system 20 allows the raw materials to be
oriented either toward a conduit 21 distributing the latter centrally above the
cone 5, or toward a conduit 22 distributing these vitrifiable materials near to the
lowest point 23 of the furnace bottom 2. The distribution by the conduit 22 takes
place at the start of the filling of the furnace in such a manner as to accumulate
a maximum amount of molten material in the corner 23 as quickly as possible.
This accumulation of a small quantity of the molten materials at the start of the
process allows the furnace to be primed. When the raw materials are engaged
via the conduit 22 close to the vertical passing through the lowest point 23 of
the furnace bottom, the electrodes 9 are also displaced, horizontally, so as to be
located near to a vertical passing through the lowest point 23. Where required,
a drainage plug 24 allows the furnace to be drained.
Figure 3 shows the relative positions of the device for distribution of the
raw materials and of the electrodes, in a top view, for the furnace in figure 2.
The cylindrical wall 15 of the furnace and the distribution channel 11 can be
seen. At the start of the filling (figure 3 a)), the raw materials are introduced via
the closest possible conduit 22 above the lowest point 23 (see figure 2). The
electrodes 9 are situated as near as possible above this lowest point 23. In a
continuous production process (figure 3 b)), the raw materials are introduced via
the conduit 21 in the center of the furnace. The electrodes 9 have been moved
so as to surround the center of the furnace.
EXAMPLES
Powdered raw material of the oxide type is introduced into a furnace of
the type of that shown in figure 1 so as to form the glass charge comprising:
Silica: 43%
Alumina: 21%
Iron oxides: 6%
CaO+MgO: 17%
Na O+K O: 11%
TiO : 0.7%
A power of 630 kilowatts is supplied via electrodes. The height of the
dam was varied and the temperature was measured for various heights in
continuous mode and for a constant output of 10 tons per day. The table 1
hereinbelow presents the results for various distances between the furnace
bottom and the lowest point of the dam.
Height under dam Temperature of the glass
just after the dam
120 mm 1350°C
140 mm 1410°C
150 mm 1450°C
Table 1
The term ‘comprising’ as used in this specification and claims means
‘consisting at least in part of’. When interpreting statements in this specification
and claims which include the term ‘comprising’, other features besides the
features prefaced by this term in each statement can also be present. Related
terms such as ‘comprise’ and ‘comprised’ are to be interpreted in similar
manner.
Claims (18)
1. A process of fabrication of mineral fibers comprising the introduction of raw materials into a circular furnace with electrodes, then the fusion of the raw materials in said furnace in order to form a molten vitrifiable 5 material, then the outflow of the molten vitrifiable material in the furnace via a lateral outlet from the furnace so as to supply a distribution channel, then the outflow of the molten vitrifiable material via an orifice on the furnace bottom of the distribution channel so as to supply a fiber forming device, then the transformation into fibers of 10 the molten vitrifiable material by said fiber forming device, wherein the flow of molten vitrifiable material between the furnace and the distribution channel passes under a metal dam being adjustable in height comprising an envelope cooled by a flow of cooling fluid.
2. The process as claimed in the preceding claim, characterized in that 15 the molten vitrifiable material comprises more than 2% by weight of iron oxide.
3. The process as claimed in the preceding claim, characterized in that the molten vitrifiable materials comprise more than 3% by weight of iron oxide. 20
4. The process as claimed in the preceding claim, characterized in that the molten vitrifiable material comprises more than 4% by weight of iron oxide.
5. The process as claimed in one of the preceding claims, characterized in that the molten vitrifiable material comprises less than 20% by 25 weight of iron oxide.
6. The process as claimed in one of the preceding claims, characterized in that the molten vitrifiable material passing under the dam has a temperature greater than its devitrification temperature.
7. The process as claimed in one of the preceding claims, characterized 30 in that the molten vitrifiable material passing under the dam has a temperature in the range between 850 and 1700°C.
8. The process as claimed in one of the preceding claims, characterized in that the molten vitrifiable material comprises 1 to 30% of alumina.
9. The process as claimed in the preceding claim, characterized in that the molten vitrifiable material comprises 15 to 30% of alumina.
10. The process as claimed in the preceding claim, characterized in that the molten vitrifiable material passing under the dam has a 5 temperature in the range between 1200 and 1700°C.
11. The process as claimed in one of the preceding claims, characterized in that the dam has a width in the range between 20 and 60 cm.
12. The process as claimed in one of the preceding claims, characterized in that the bottom of the furnace has a surface area in the range 10 between 1 and 25 m².
13. The process as claimed in one of the preceding claims, characterized in that the output of the furnace is in the range between 5 and 100 tons per day.
14. The process as claimed in one of the preceding claims, characterized 15 in that the height of the dam is adjusted such that the viscosity of the molten vitrifiable material is in the range between 25 Pa.s and 120 Pa.s in the fiber forming device.
15. The process as claimed in one of the preceding claims, characterized in that the electrodes are submerged from above in the vitrifiable 20 materials.
16. The process as claimed in one of the preceding claims, characterized in that the part of the electrodes in contact with the vitrifiable materials is made of molybdenum.
17. The process as claimed in one of the preceding claims, characterized 25 in that the transformation into fibers is the step that determines the output.
18. The process as claimed in claim 1, substantially as herein described with reference to any embodiment disclosed.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1162500A FR2985254B1 (en) | 2011-12-28 | 2011-12-28 | METHOD FOR FIBRING VITREOUS MATERIALS |
FR1162500 | 2011-12-28 | ||
PCT/FR2012/052978 WO2013098504A1 (en) | 2011-12-28 | 2012-12-18 | Method for drawing vitrifiable materials |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ627176A NZ627176A (en) | 2015-07-31 |
NZ627176B2 true NZ627176B2 (en) | 2015-11-03 |
Family
ID=
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