Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Method for ProducingInsulating Materials from Mineral Fibers
This invention relates to a method for producing insulating materials from
mineral fi-
bers, especially from glass and/or rockwool, wherein a silicate melt is
prepared in a
melting unit, especially a cupola furnace, and is disintegrated in a
disintegration unit to
preferably microfine fibers, and wherein a binder and/or proofing agent is
added to the
fibers and the fibers are placed on a conveyor means in the form of a fibrous
web.
The invention further relates to a melt for producing mineral fibers for a
mineral fiber
web.
Insulating materials made from mineral fibers are produced from silicious
melts. To this
end a silicious starting material, e.g. glasses, natural or artificial stone,
are fed for ex-
ample to a cupola furnace or shaft furnace. The silicious melt thus obtained
is then fed
to a disintegration unit where the silicious melt is disintegrated to
microfine mineral
fibers. The mineral fibers which are thereafter supplied to a collecting
chamber are as a
rule wetted with binders and/or proofing agents and are placed on a conveyor
means,
usually a coveyor belt, arranged under the collecting chamber. The mineral
fibers wet-
ted with binder and/or proofing agents form on said conveyor means a mineral
fiber
web which is treated in a manner known per se in downstream thermal and/or
mechani-
cal devices, in order to produce insulating materials in the form of webs,
boards,
moulded bodies or the like.
With insulating materials made from mineral fibers a difference is made
between those
from glass wool and those from rockwool. Rockwool insulating materials usually
have
been melted open from stones like diabase, basalt and limestone, dolomite. In
the
meantime, these natural stones are increasingly replaced by artificial stones
or are sub-
ject to the melting process together with artificial stones. In this melting
process, which
mostly takes place in cupola furnaces, there exists a strong dependence
between the
viscosity and temperature. Moreover, the nucleation number and hence the
tendency to
crystallization are very high. At the formation of the mineral fibers on so-
called cascade
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spinning machines these properties lead to relatively short mineral fibers
which are
swirled in themselves. The individual mineral fibers per se have a glassy
solidified ap-
pearance. Due to their composition the temperature resistance of mineral
fibers pro-
duced from a melt of rock is higher than that of insulating materials from
glass wool.
Glass wool insulating materials contain as a network transformer
overwhelmingly so-
dium oxide and boroxide. The melt for glass wool insultating materials
exhibits a
weakly developed dependence of the viscosity from temperature. The
disintegration of
this glass melt does not take place on cascade spinning machines, but is
effected with
the aid of rotating bowl-shaped bodies, of which the walls include bores. Due
to the
centrifugal force which is produced in this case the glass melt is forced
through these
bores, so that mineral fibers are extruded from glass wool which have a longer
length
compared to those from rock wool.
An important factor at the production and evaluation of mineral fibers is the
biosolubil-
ity, i.e. the dwell time of the mineral fibers in the human organism. The
biosolubility of
insulating materials from rockwool is decisively influenced by the A1203
content. With
increasing A1203 moieties the temperature resistence of the fibers increases
on the one
hand and, surprisingly, on the other hand also the biosolubility.
A typical composition of biosoluble mineral fibers from rockwool includes a
moiety of
Si02 between 35 and 43 % by weight, a moiety of A1203 of 17.5 to 23.5 % by
weight, a
moiety of Ti02 of 0.1 to 3 % by weight, a moitey of FeO of 1.7 to 9.3 % by
weight, a
moiety of CaO + MgO of 23.5 to 32 % by weight, and a moiety of K20 + Na2 of
1.3 to
7 % by weight.
An important criterion for the economy of insulating materials from rockwool
as a mass
product is the use of raw materials comprising a high moiety of A1203. Even
though
natural stones frequently include aluminosilicates, they are often not
available in the
required concentrations or only together with undesired minerals. Calcined
bauxites, on
the other hand, are comparatively expensive. For this reason, residual
materials are fre-
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quently utilized which, up to present, were mostly only suitable for dumping
and con-
stituted a considerable risk to the environment because of their content of
soluble sub-
stances. At the same time these residual materials accrueing on the production
of rock-
wool, for example in the form of melt residues, separated non-fibrous
particles, filtering
dusts, misproductions or the like are almost completely recycled in a primary
recycling
system. These residual materials are conditioned prior to their recycling, so
that they
comply with the requirements of the machine equipment, particularly the
melting unit.
For their recycling these residual materials are for example comminuted and
mixed with
each other or with other splintery raw materials at different grain sizes,
compounded
with binders such as cement and pressed to sufficiently large moulded bodies
before
these moulded bodies are supplied as lumpy raw materials to a shaft furnace or
cupola
furnace. From the EP 0 765 295 Cl for example it is known to bind suitable
moulded
bodies from fine-grained raw materials also with the aid of lignin. In WO
94/12007 cor-
responding moulded bodies with molasses-containing binders are described.
In view of this prior art the invention is based on the problem of improving
said method
and said melt in such a manner that the method can be carried out at lower
costs or that
an inexpensive melt is provided by using inexpensive starting materials.
The solution of this problem provides that in a method of this kind the
silicious melt is
at least partly prepared from oil refining catalysts, particularly from those
which are no
longer usable.
Accordingly, the invention provides that in a method which is known per se the
silicious
melt is at least partly produced from oil refining catalsysts, particularly
from those
which are no longer usable.
Mineral oils consists of mixtures of high-molecular to low-molecular
compounds. They
serve as raw materials for a number of substances like fuels, base products
for the pro-
duction of polymers, or as starting material for bitumen and asphalts. At the
different
stages of processing a number of processes like the hydrating, dehydrating,
oxidizing or
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reducing of intermediate products run in an economical way only under the use
of cata-
lysts.
In this respect the catalysts are classified in two classes. On one side,
redox catalysts
like chromic oxide or vanadium pentoxide, metals such as platinum, palladium
or nickel
are used which catalytically influence the hydrating, dehydrating and
oxidizing pro-
cesses. Here the metals are seated on e.g. aluminium oxide supporting
materials. On the
other side, acid-base-catalysts find use for isomerization, alkylation or
cracking reac-
tions that run via ion-like intermediate stages. Typical acid-base-catalysts
consist of
acidic aluminium oxides, aluminosilicates or zeolites. Those kinds of
catalysts have a
relatively long useful time, since they can be repeatedly regenerated. These
catalysts
need to be replaced for example in case of the addition of coke or of so-
called catalyst
poisons or in case of a decreasing specific surface area of noble metals as a
conse-
quence of recrystallization. At higher standards the noble metals contained in
the cata-
lysts can be economically recovered.
However, used catalysts accrueing on catcracking or hydrocracking are normally
waste,
of which the recycling is economical only in few other processes, in order to
protect the
environment.
For example, in order to obtain high-quality fuels from mineral oils,
distillation prod-
ucts from mineral oil are subject to a catalytic cracking process. The
treatment mostly
takes place in fluid-bed reactors. The catalytic cracking reactions take place
in the pres-
ence of acidic catalysts according to a carbonium ion mechanism. As usual
catalysts
aluminosilicates doped with protons are mostly used. These catalysts replace
the for-
merly used acid-treated clay minerals of the montmorillonite group which have
been
replaced because of their crystallinity and the present impurities caused for
example by
iron or by amorphous aluminosilicates. Commercially available amorphous
aluminosili-
cates contain approx 10 to 15 % by weight of A1203, but there are also known
alumi-
nosilicates having an A1203 content of between 20 to 30 % by weight.
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Economically much more important and hence much more popular are catalysts
from
synthetic zeolites with the crystal structure of the mineral faujasite.
Suitable zeolites are
for example produced by Union Carbide under the name Linde type X or Linde
type Y.
The total formula of these two zeolite types is:
Linde type X: Na86[A102)86(SiO2)1o6] x H20
Linde type Y: Na56[Al02)56(SiO2)136] x H20
The chemical efficiency extremely increases with the exchange of the NA ions
for tri-
valent ions like for example lantane, lantanides or other rare earths.
Accordingly, as the
most efficient catalysts so-called H-RE-faujasites are used, wherein "RE" is
the abbre-
viation for "rare earths".
From various technical reasons like increasing the resistance to abrasion,
thermal sta-
bility and for a better distribution of the active substances it is useful
that the zeolite
catalysts are distributed in a matrix of silica gel, amorphous
aluminosilicates or clays.
The H-RE-faujasite is, for example, embedded at relatively small amounts in
amor-
phous aluminosilicates. Zeolite catalysts work more selectively than amorphous
alumi-
nosilicates, the latter boosting the formation of olefines. Such catalysts
have a high open
porosity and a large specific surface area, which are favourable and necessary
for their
function as a catalyst in the catcracking process. By the separation of coke
the active
centers of the catalysts are deactivated. Cleaning of the expensive catalysts
is effected,
for example, by a careful burning-off of the coke depositions. However, any
complete
cleaning cannot be guaranteed, so that the service life of such a catalyst is
limited even
though it is regularly cleaned.
A permanent deactivation of the catalysts can be caused in addition by metal
com-
pounds in the distillates. Such metals in distillates are in the first line
vanadium, nickel
and/or iron which themselves act as catalysts and cause undesired reactions.
Due to a
decrease in the catalytic activity and in selectivity catalysts become
unusable and need
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to be exchanged. As a rule, such catalysts are dumped as waste material,
unless they can
be recycled in an economical way in other processes.
Catalysts herein described are used in so-called fixed-bed reactors and are
available in
the form of particles having a good flowability and a grain size of 3 to 4 mm.
If fluid-
bed reactors are used, catalysts will be selected, of which the particles have
an average
diameter of approx 50 to 70 m.
Methods for the refining hydration of mineral oil fractions are part of the so-
called hy-
drotreatings, of which the various techniques are used for example in order to
separate
harmful or inhibiting tramp materials. To this end catalysts are used which
are based
among others on the use of cobalt and molybdenum oxides with aluminium oxide
as a
supporting medium. Such catalysts are available in the form of extrudates and
have an
initial length of approx 2.5 to 3 mm.
Finally, for the breaking hydration of mineral oil fractions hydrocracking
methods are
applied in which typical hydrocrack catalysts are used that contain tor
example metals
like nickel or tungsten in amounts of approx 15 to 25% by weight or CoO + MoO3
with
moieties of approx 22 to 28% by weight as well as support medium. The support
medium either consists of almost pure A1203 or of aluminium silicates.
Surprisingly it has shown now that the above-described catalysts in the used
state are
particularly suited as supplementary raw materials fiir the production of
insulating mate-
rials from mineral wool.
According to a further feature of the invention it is advantageous to use as
catalysts
those from cracking and hydrocracking processes which are very well suited as
substi-
tute raw materials, particularly for the production of rockwool insulating
materials. As a
characteristic parameter Si02 in moieties of approx 30 to approx 55 % by
weight and
A1203 in moieties of between about 30 to 50 % by weight can be mentioned as
main
constituents.
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However, also catalysts can be used which consist of zeolite, wherein the
above-de-
scribed zeolites of the type Linde are of interest when the sodium content is
reduced in
order to avoid an excessive content of alkalies in the insulating material.
All the other
constituents of the catalysts are of minor importance and can thus be added to
the melt
without any negative effects.
A further feature of the invention provides that metals which precipitate
during the
melting-open of the catalysts are collected and periodically drained.
Preferably, the
metals are collected and periodically drained together with the metallic iron
reduced
from the raw materials. Here it is advantageous that the melting units, for
example the
cupola furnaces, have no fire-resistant liniiig in their actual shaft region,
so that the me-
tals present in the catalysts are no danger for the melting unit.
According to an advantageous further improvement of the method according to
the in-
vention it is provided that oxidic components contained in the melt, such as
rare earths
like La203, CeOz, Pr6011, are dissolved in the melt.
A further feature of the invention provides that the melt is prepared from the
catalysts
and the usual raw materials for the production of insulating materials from
mineral fi-
bers, particularly diabase, basalt and limestone as well as dolomite, and/or
from the re-
sidual material obtained during the production or recycling. Accordingly, it
is provided
in this embodiment that the catalysts are merely a constituent of the melt of
which the
moiety within the melt is adjusted corresponding to the required quality level
of the
insulating materials.
According to a further feature of the invention the fine-grained catalyst
masses are
pressed to lumpy bodies before they are melted. Preferably, the fine-grained
catalyst
masses are mixed together with the residual material from the primary waste
cycle and
stones used as supporting grain as well as binders like hydraulic cements,
latent-hy-
draulic materials, lime and/or lignin, molasses or the like, and pressed to
lumpy bodies.
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After they have hardened, these lumpy bodies together with lumpy stones and
coke are
fed to a melting unit where they are melted open. In this connection it is
advantageous
that the constituents of the melt are thoroughly mixed before they are
supplied to the
melting unit.
Alternatively, the catalysts can be fully or at least partly blown as a fine-
grained mass
into the melting unit, particularly a shaft furnace, through blast forming. To
avoid or
reduce a decrease in temperature within the melting zone of the furnace it has
proved
that preheating the catalyst particles is advantageous, wherein a maximum
preheating
temperature of 600 C should be striven for.
In addition to the above-described method the present invention is also
concerned with a
melt for producing mineral fibers for a mineral fiber web, particularly from
rockwool,
which can be further made into insulating materials. The melt according to the
invention
is characterized by oil refining catalysts that are no longer usable.
Preferably, the catalysts originate from cracking and/or hydrocracking
processes which
have shown to be very good substitute raw materials for the production of rock
wool
insulating materials.
A further feature of the melt according to the invention provides that the
catalysts are
mixed with residual materials from the primary waste cycle and/or recycling
materials
from mineral fiber production. Such a mixture is particularly suited for the
production
of rock wool insulating materials of sufficiently high quality.
Preferably, the melt according to the invention includes 20 to 60 % by weight
of Si02
and 10 to 60 % by weight, particularly 10 to 30 % by weight of A1203.
The catalysts available in the melt preferably have a grain size of between 2
and 6 mm,
particularly of between 3 and 4 mm, so that the same are suitable for being
pressed to
lumpy bodies to be fed to a melting unit on the one hand, and for being blown
into a
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shaft furnace on the other hand. To this end catalysts from fixed bed reactors
can be
used, for example, which are available in the form of particles exhibiting
good flow-
ability. But alternatively also catalyst particles are suited which are used
in fluid bed
reactors and which have an average diameter of 30 to 100 m and preferably of
between
50 and 70 m.
Another alternative are catalysts that are used in processes for the refining
hydration of
mineral oil fractions. With such catalysts a configuration as extrudates can
be deter-
mined, of which the length preferably is between 1 and 5 mm, particularly
between 2.5
and 3 mm.
Finally, a further feature of the invention provides that the catalysts
include 10 to 30 %
by weight, particularly 15 to 25 % by weight of metals like nickel or tungsten
or 15 to
35 % by weight and preferably 22 to 28 % by weight of cobalt oxide and
molybdenum
oxide. As a supporting material in such catalysts aluminium oxide is provided.
Further features of the method according to the invention or of the melt
according to the
invention become apparent from the following description of preferred
embodiments.
First Embodiment
For producing a melt a cupola furnace is charged with lumpy material that
consists at
15% of a catalyst material and at 85% of artificial stones. As catalyst
material amor-
phous aluminium silicate catalysts from hydrocracking processes with 12.5% by
weight
of A1203 are used. The artificial stones consist at 60% of recycling material
and at 40%
of re-built mineral fiber insulating materials, wherein the recycling material
is taken
from the production process in the form of cuttings or low-quality products.
The mate-
rial to be fed is pressed from fine-grained catalyst material and the test
material required
for the artificial stones together with stones used as supporting grain with
latent-hy-
draulic materials to lumpy bodies.
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Second Embodiment
For producing a silicious melt which serves for producing fibrous insulating
materials a
cupola furnace is charged with lumpy material that consists at 25% of a
catalyst mate-
rial, at 20% of natural stone, and at 55% of artificial stones. As a catalyst
material cata-
lysts from mineral ol refining which are no longer usable are chosen, of which
the main
constituents are Si02 and A1203, wherein the catalyst material includes a
moiety of 45%
by weight of Si02 and 40% by weight of A1203 as well as further oxidic
constituents
like rare earths and metal. As natural stone diabase, basalt and limestone as
well as
dolomite are used. The artificial stone is composed of residual materials
accrueing on
the production of fibrous insulating materials or on the re-building of
fibrous insulating
rnaterial, the proportion of the recycling material as a result of
manufacturing being
70%, and the proportion obtained from re-building being 30%.
The catalyst material and the residual material that is to be made into
artificial stones
are prepared into a fine-grained material and are mixed with lime and lignin
and pressed
to lumpy bodies. Thereafter, the feeding material is fed to the cupola furnace
as a frac-
tion mixed from natural stone and lumpy bodies consisting of catalyst material
and arti-
ficial stone and melted therein and is subsequently fed to a disintegration
unit in which
the melt is disintegrated to microfine fibers which are then placed on a
conveyor belt in
the form of a mineral fiber web. Therafter, the mineral fiber web is
mechanically and
thermally treated, in order to produce the desired mineral fiber insulating
materials.
Third Embodiment
Also in the third embodiment catalyst material, natural stones and artificial
stones are
fed as charging material to a cupola furnace, with a mixture of 45% catalyst
material,
20% natural stone, and 35% artificial stones being provided. The artificial
stones are
composed of 80% of recycling material and 20% of re-building material, said
recycling
material and re-building material being prepared into a fine-grained structure
together
with the catalyst material and pressed to lumpy charging material. To this end
a binder
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is used including hydraulic cement. The production of the mineral fiber
insulating mate-
rial then takes place in the above-described way.
