Process for the Manufacture of a New Refractory Material,
Year: 1898

page_text: Date of Application, 24th Feb., 1898
PROVISIONAL SPECIFICATION.
Process for the Manufacture of a New Refractory Material,
I, ALEXANDER IMSCHENETZKY, of No. 2, Tikhvinskaya, St. Petersburg, Russia,
Lieutenant Colonel, do hereby declare the nature of this invention to be as
follows:-
In my Specification No. 5254 of 1895 I have described a process for preparing
a fireproof material, which I have termed Uralite," consisting in saturating a
mass of asbestos fibres with a solution of hydrated silica (SiU,)n (HU)m pre-
pared by mixing a solution of a silicate with a suitable acid (such as hydrochloric
acid, sulphuric acid, and the like) sufficiently diluted with water to ensure that
the hydrated silica shall not gelatinise at once but slowly enough to permit the
penetration of the solution into all the interstices of the mass before the colloidal
form is assumed. If the colloidal substance thus deposited in the asbestos fibres
be allowed to dry slowly these are cemented together in such a way that they
cannot be separated even by boiling water.
I have found, however, that the mass prepared in this way cannot resist a
bending stress, because it is not possible to introduce at once a large quantity
of the solution of silica into the interstices, by reason of the fact that the retar-
dation of the formation of the colloidal silica is only possible when the solution
is sufficiently dilute; when a strong solution of silica is used the colloid forms
before the solution has penetrated into all the interstices of the mass.
To pro-
duce a mass of the desired degree of solidity it is necessary to repeat the satura-
tion with the silica solution several times; the cost of the manufacture is thus
increased.
There are several objections to a process consisting in impregnating the
asbestos first with a solution of a silicate and then with acid, for the purpose of
depositing silica in the fibre; in the first place every kind of asbestos will not
withstand the action of acids, some being rendered fragile thereby; in the second
place the method will not allow of the intermixture with the mass of any sub-
stance attackable by the acid, for example chalk, lime, magnesium carbonate or
magnesium hydrate. The small proportion of acid used would speedily be
neutralized by the chalk, &c., leaving the sodium silicate unattacked; further-
more, the action of the acid on the substances mentioned would cause evolution
of carbon dioxide which would distort the mass; finally the admixture would be
dissolved by the acid. These points are important, since an admixture of two
kilos and more of chalk to one kilo of asbestos can be made without
prejudice to the product, greatly reducing the cost of manufacture and thereby
rendering the material applicable to a number of purposes for which it would
otherwise be too dear.
This invention relates to a new process for cementing the mass of asbestos
by silica, whereby a large quantity of colloidal silica can be introduced at one
operation by means of agents which have no chemical action on the substances
mixed with the asbestos; furthermore, the by products of the reaction by which

page_text: objects are then pressed to give them a regular snap which shall not alter during
the subsequent operations and are again dried. They are now impregnated with
a strong solution of sodium silicate Na„Si̟0, (of a specific gravity from 30° to 36°
Beaume) and once more dried. The objects are next soaked during 24 hours or
longer, according to their thickness in a saturated solution of sodium bicar-
bonate. NaHCO3, potassium bicarbonate KHCO3, or ammonium bicarbonate
NHHCO3.
The sodium silicate contained in the pores of the material is
gradually decomposed by this solution in accordance with the chemical equation;
NaSiO, 2NaHCO, 4SiO2+2NaCO3 + H₂O.
The silica remains in the pores and the sodium carbonate passes into the
solution, so that the sodium bicarbonate in the latter becomes converted into
sodium carbonate.
The improvements achieved by the introduction of sodium bicarbonate into
the manufacture of Uralite are as follows;-
"
-
1) The reaction between the sodium bicarbonate and the sodium silicate
allows of the use of strong solutions of sodium silicate and therefore of the depo-
sition of larger quantities of silica in the pores of the mass than is the case
when comparatively weak solutions of silica are used; the solidity of the product
is thus increased.
2) Sodium bicarbonate has no chemical action on the constituents of the mass
and therefore no influence on its constitution; this would not be the case if acid
were used.
3) Sodium bicarbonate does not evolve any gas which would inflate the
objects and disintegrate them.
4) From what is said under 2) it follows that all the sodium bicarbonate is
used productively, since it is only used up in reacting with the sodium silicate,
which is not the case if acids which react with the admixture in the mass are
used.
5) When sodium bicarbonate is used the reaction which determines the libera-
tion of the silica produces at the same time sodium carbonate as a by product,
and from this sodium bicarbonate can be regenerated; thus the by-product can
be used again in the manufacture and compensates for loss of primary materials.
When acids are used the by product is a solution of sodium sulphate or sodium
chloride which are of no further value in the process.
6) When the silicate is treated with sulphuric or hydrochloric acid (which
should be in excess) there is formed in the solution a mixture of acid indispen-
sable for the reaction, and a salt quite useless in the reaction; thus the propor-
tion of acid contained in the solution cannot be determined by an hydrometer,
and the determination becomes too complicated for a large scale of manufacture.
Besides, when such a solution becomes too rich in salt it must be discarded
in spite of its content of acid, for the cost of separation is too great; on the con-
- trary, the sodium carbonate produced when the sodium silicate is treated with
sodium bicarbonate does no harm in the solution.
7) When sodium bicarbonate is used the regeneration of the product of the
reaction is simply effected by passing carbon dioxide through the solution after
the objects have been withdrawn, or even while they are still soaking.

page_text: The treatment of the objects with the silicate and bicarbonate can be repeated,
if it be desired to impart to the manufactured articles a greater degree of solidity;
the drying after impregnation with sodium silicate can be dispensed with and
they can be directly immersed in the solution of sodium bicarbonate, but in this
case the action is slower. In order that the solution of sodium bicarbonate which
is to be used for the treatment of objects made of Uralite" may not be deterio-
rated by the introduction of salts other than sodium carbonate, the solution of
silica for the first cementation can be prepared not only with sodium silicate and
sulphuric acid or hydrochloric acid, but also with sodium silicate and bicarbonate
of sodium, potassium or ammonium. In this case there are used, for example,
one volume of a solution of sodium bicarbonate of specific gravity 5° Beaumé
and two volumes of a solution of sodium silicate of specific gravity 15° Beaumé.
The objects impregnated with the silicate can be treated still more simply
with a solution of carbonic acid for the purpose of liberating the silica.
They are placed in a receiver filled with water and hermetically closed; carbon
dioxide is introduced under pressure more or less high; after 24 hours the surplus
gas is allowed to escape and the objects are withdrawn and dried. The carbon
dioxide and the liquid can be used again, the latter being a solution of sodium
bicarbonate which can be used for making a solution of silica for the first
cementation of the objects.
After cementation the objects made of "Uralite" may be coated with a layer
of mineral pigment capable of resisting the action of water and high tempera-
ture. The colour can be spread on plain surfaces, for example on sheets of
Uralite," by means of machines such as are used in the manufacture of oil-cloth.
The colour may be prepared as follows:-
The dry pigment is mixed with silicate and spread on the surface of "Uralite "
which is then dried and treated with a solution of calcium chloride or magnesium
chloride; there is thus produced on the surfaces prepared in this way a silicated
colour which adheres very firmly to the surface of the Uralite and is attacked
neither by water nor by a high temperature (300-400°C.).
Dated this 24th day of February 1898.
"
"
ABEL & IMRAY,
Agents for the Applicant.
I, ALEXANDER IMSCHENETZKY, of 2, Tikhvinskaya, St. Petersburg, Russia,
do hereby declare the nature of this invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the
following statement:-
In my Specification No. 5254 of 1895 I have described a process for preparing
a fireproof material, or artificial stone which I have termed Uralite" consisting
in saturating a mass of asbestos fibres with a solution of hydrated silica (SiO2)
(HO)m prepared by mixing a solution of a silicate with a suitable acid (such as
hydrochloric acid, sulphuric acid, and the like,) sufficiently diluted with water
to ensure that the hydrated silica shall not gelatinise at once but slowly enough
to permit the penetration of the solution into all the interstices of the mass before
the colloidal form is assumed. If the colloidal substance thus deposited in the
asbestos fibres be allowed to dry slowly, these are cemented together in such a
way that they cannot be separated even by boiling water. have found how-
ever that the mass prepared in this way cannot resist a bending stress, because it
is not possible to introduce at once a large quantity of the solution of silica into

page_text: the interstices, by reason of the fact that the retardation of the formation of the
colloidal silica is only possible when the solution is sufficiently dalute; when a
strong solution of silica is used the colloidal forms before the solution has pene-
trated into all the interstices of the niass. To produce a mass of the desired
degree of solidity it is necessary to repeat the saturation with the silica solution
several times; the cost of the manufacture is thus increased. 'There are several
objections to a process consisting in impregnating the asbestos first with a solu-
tion of a silicate and then with acid for the purpose of depositing silica in the
fibre; in the first place every kind of asbestos will not withstand the action of
acids, some being rendered fragile thereby, in the second place the method will
not allow of the intermixture with the mass of any substance attackable by the
acid, for example chalk, lime, magnesium carbonate or magnesium hydrate.
The small proportion of acid used: would speedily be neutralized by the chalk, &c.,
leaving the sodium silicate unattacked; furthermore the action of the acid on
the substances mentioned would cause evolution of carbon dioxide which would
distort the mass; finally the admixture would be dissolved by the acid. These
points are important, since an admixture of two kilos and more of chalk to one
kilo of asbestos can be made without prejudice to the product, greatly reducing
the cost of manufacture and thereby rendering the material applicable to a number
of purposes for which it would otherwise be too dear.
This invention relates to a new process for cementing the mass of asbestos by
silica, whereby a large quantity of colloidal silica can be introduced at one
operation by means of agents which have no chemical action on the substances
mixed with the asbestos; furthermore, the by-products of the reaction by which
the silica is liberated can be recovered without much expense or difficulty in a
form suitable for further use. As in the earlier process, the asbestos fibres are
first separated and then kneaded with water to obtain a paste capable
of being formed into sheets, either manually or mechanically, like paper pulp.
The paste is then mixed with the carbonates or oxides of calcium, magnesium,
iron or the like, for the purpose of cheapening the product or of reducing its
specific gravity or of modifying its colour. This paste is made into sheets or
into objects of any desired form, which are dried and cemented with a solution
of silica as in the earlier process. The objects are then pressed to give them a
regular shape which shall not alter during the subsequent operations and are
again dried. They are
now impregnated with a strong solution of sodium
silicate Na,On(SiO2) (of a specific gravity from 30° to 36° Beaumé) and once
more dried. The objects are next soaked during 24 hours or longer, according
to their thickness in a saturated solution of sodium bicarbonate NaHCO3, potas-
sium bicarbonate KHCO, or ammonium bicarbonate NHHCO3.
As it is evident that for reasons of cheapness and on other grounds sodium
would be chosen in the process in preference to potassium or ammonium, I shall
throughout the rest of the specification describe the process with reference to
sodium. It will be obvious that the other alkalies could be used if desirable.
The sodium silicate contained in the pores of the material is gradually decom-
posed by this solution in accordance with the chemical equation:
==
Na,On(SiO2)+2NaHCO₁ = n(SiO2) + 2Na₂CO, + H₂O.
The silica remains in the pores and the sodium, carbonate passes into the
solution, so that the sodium bicarbonate in the latter becomes converted into
sodium carbonate.
The improvements achieved by the introduction of sodium bicarbonate into
the manufacture of uralite are as follows:
(1.) The reaction between the sodium bicarbonate and the sodium silicate
allows of the use of strong solutions of sodium silicate and therefore of the depo-
sition of larger quantities of silica in the pores of the mass than is the case
when comparatively weak solutions of silica are used; the solidity of the product
is thus increased.

page_text: (2.) Sodium bicarbonate has no chemical action on the constituents' of the mass
and therefore no influence on its constitution; this would not be the case if acid
were used.
(3.) Sodium bicarbonate does not evolve any gas which would inflate the
objects and disintegrate them.
(4.) From what is said under (2) it follows that all the sodium bicarbonate is
used productively, since it is only used up in reacting with the sodium silicate
which is not the case if acids, which react with the admixture in the mass, are
Lused.
(5.) When sodium bicarbonate is used the reaction which determines the libera-
tion of the silica produces at the same time sodium carbonate as a by-product
and from this sodium bicarbonate can be regenerated; thus the by-product can
be used again in the manufacture and compensates for loss of primary materials.
When acids are used the by product is a solution of sodium sulphate or sodium
chloride which are of no further value in the process.
(6.) When the silicate is treated with sulphuric or hydrochloric acid (which
should be in excess) there is formed in the solution a mixture of acid indispen-
sable for the reaction, and a salt quite useless in the reaction; thus the propor-
tion of acid contained in the solution cannot be determined by an hydrometer,
and the determination becomes too complicated for a large scale of manufacture.
Besides, when such a solution becomes too rich in salt it must be discarded
in spite of its content of acid, for the cost of separation is too great; on the con-
trary, the sodium carbonate product, when the sodium silicate is treated with
sodium bicarbonate, does no harm in the solution.
(7.) When sodium bicarbonate is used the regeneration of the product of the
reaction is simply effected, by passing carbon dioxide through the solution after
the objects have been withdrawn, or even while they are still soaking.
The treatment of the objects with the silicate and bicarbonate can be repeated,
if it be desired to impart to the manufactured articles a greater degree of solidity:
the drying after impregnation with sodium silicate can be dispensed with and
they can be directly immersed in the sodium bicarbonate, but in this case the
action is slower. In order that the solution of sodium bicarbonate which is to
be used for the treatment of objects made of uralite may not be deteriorated by
the introduction of salts other than sodium carbonate, the solution of silica for
the first cementing can be prepared not only with sodium silicate and sulphuric
acid or hydrochloric acid, but also with sodium silicate and bicarbonate of sodium,
potassium or ammonium. In this case there are used, for example, one volume
of a solution of sodium bicarbonate of specific gravity 5° Beaumé and two
volumes of a solution of sodium silicate of specific gravity 15° Beaumé.
Care must be taken that the solution does not produce the colloid form too
rapidly to enable the mass to be thoroughly permeated by the solution. In the
first treatment the silicate may also be applied first and the steeping in bicar-
bonate follow, in the same way as is herein above described with reference to the
later stages of the process when it has been commenced with a solution of silicate
to which acid is added.
Instead of using sodium bicarbonate the objects impregnated with the silicate
can be treated with a solution of carbonic acid for the purpose of liberating the
silica.
They are placed in a receiver filled with water and hermetically closed, carbon
dioxide is introduced under pressure more or less high; after 24 hours the
surplus gas is drawn off or allowed to escape and the objects are withdrawn and
dried. The liquid can be used again, as it is a solution of sodium bicarbonate
or carbonate which can be used for making a solution of silica for the first
described method of cementing the objects.
After cementing, the objects made of "Uralite" may be coated with a layer
of mineral pigment capable of resisting the action of water and high tempera-
ture. The colour can be spread on plain surfaces for example on sheets of

page_text: "Uralite" by means of machines such as are used in the manufacture of oil
cloth. The colour may be prepared as follows:-The dry pigment is mixed
with the silicate and spread on the surface of "Uralite" which is then dried and
treated with a solution of calcium chloride or magnesium chloride: there is
then produced on the surfaces prepared in this way a silicated colour which
adheres very firmly to the surface of the "uralite" and is attacked neither
by water nor by high temperature (300° to 400°C.).
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. The process of manufacturing artificial stone which consists in first satu-
rating articles made of asbestos, with or without admixture of other sub-
stances, with a silicate solution, and then treating the same with a bicarbonate
solution, substantially as and for the purposes described.
2. The process of manufacturing artificial stone, which consists in first satu-
rating articles made of asbestos with or without admixture of other materials,
with a silicate solution, and then soaking the same in a bicarbonate solution in
order to convert the asbestos silicate into silica and at the same time obtain a
carbonate solution, which is further available in the manufacture, substantially
as described.
3. In the process of manufacturing artificial stone from asbestos with or with-
out admixture of other ingredients by saturating the asbestos articles with a
hydrate of silica solution, the method of further saturating the articles with a
silicate solution, and then soaking them in a solution of a bicarbonate whereby
the absorbed silicate is converted into silica by taking up carbonic acid from
the bicarbonate, the resulting by product of carbonate solution thus obtained
being then available for the production of further quantities of silicate and of
bicarbonate, substantially as described.
4. The process of manufacturing artificial stone which consists in first soaking
sheets or other forms produced from asbestos pulp in a solution of hydrated
silica, then drying the same, then impregnating the same with a solution of
sodium silicate, and lastly treating the same with a solution of either sodium
bicarbonate, potassium bicarbonate, or ammonium bicarbonate, substantially as
described.
5. The process of manufacturing artificial stone which consists in saturating
the articles formed of asbestos with or without admixture of other materials
with a silicate solution and then exposing the mass to the action of carbon
dioxide under pressure and water so as to produce hydrated silica in the colloid
form and a solution of the alkaline carbonate or bicarbonate substantially as
described.
6. The process of manufacturing refractory material which consists in first
producing a solution of silica by mixing together a solution of sodium silicate
and a bicarbonate solution sufficiently weak to prevent the colloid state being
assumed too rapidly, and then saturating bodies made of asbestos with or with-
out other substances with such silica solution. substantially as described.
7. An artificial stone composed of asbestos fibre with or without admixture of
other materials bound together by pure silica produced in the mass by the con-
version of a silicate by means of a bicarbonate, or by the direct action of carbon
dioxide under pressure substantially as described.
Dated this 21st day of December 1898
ABEL & IMRAY,
Agents for the Applicant.