An Improved Manufacture of Artificial Stone, Marble, and the like.
Year: 1896

page_text: Date of Application, 5th June, 1896
Complete Specification Left, 19th Feb., 1897-Accepted, 17th Apr., 1897
PROVISIONAL SPECIFICATION.
An Improved Manufacture of Artificial Stone, Marble, and
the like.
I, WILLIAM OWEN of 51 Mervan Road, Brixton, in the County of Surrey,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
One method hitherto practised for the manufacture of artificial stone is to mix
dry sand and unslaked lime or other suitable materials in a mould box which is
then placed in a cylinder; after being tightly closed the cylinder is filled with
water, and steam is then let into the water for the double purpose of imparting
pressure and heat thereto, the pressure counteracting that generated within the
box during the formation of the stone. By this method large quantities of air and
gases brought into the cylinder by the steam and also already contained in the
water itself are forced into the mould box and form innumerable air cracks in the
mass therein contained, with the result that it is impossible to produce a perfectly
sound stone. Also it is impossible to attain a high degree of temperature, for as
the pressure required in the cylinder is only fifty to sixty pounds, per square inch
it is obviously impossible to get to a higher degree of temperature than that of
slightly superheated steam itself at this pressure, say 281 to 292° F.-which has
proved not to be enough to produce a highly finished and reliable stone.
Another objection to this method is that the stone at the end of the process
soft and friable, and for several weeks is totally unfit for using in masonry.
is
I get over all these difficulties by the hereinafter described process, whereby
I produce a stone (in half the time required by the above mentioned method)
which is sound, hard, homogeneous, free from all cracks, flaws and other
imperfections, and can be used in masonry immediately after it is taken out of the
cylinders and mould box.
I require for my process a cylinder or chamber preferably of the kind hereinafter
described, and a mould-box conveniently of the type referred to in the Specification
of Letters Patent No. 19647 of 1894, granted to me, although this invention is
not limited in respect of apparatus, to that which is herein referred to by way of
example.
The aforesaid chamber may be a metal cylinder, inside the shell of which are
fixed a series of coils close to the wall with inlet connections whereby steam is
admitted to the upper end of each coil. Outlet connections are provided whereby
the exhaust is taken from the lower end of each coil. Water is delivered to the
interior of the cylinder by a suitable pipe and there is also a pipe for the exit of
water therefrom. A relief valve set to lift at any desired pressure is provided to
prevent too much stress being put upon the apparatus or applied to its contents.
The usual or other convenient cocks, valves pressure gauges and thermometers, are
provided to enable the influx, efflux, and pressure and temperature of fluid in the
apparatus to be observed and regulated as desired. A drum is placed above the
cylinder with its interior in connection by way of tubular screws with the highest
part of the interior of the cylinder. The tubular screws can be screwed through
the walls of both cylinder and drum, so that the latter is maintained in place by

page_text: of fluid in the apparatus to be observed and regulated as desired. L is a drum with
its interior in connection by way of the tubular screws 'L' with the highest part
of the interior of the cylinder. The tubular serews are screwed through the
walls of both cylinder and drum, or passed through the former and screwed into
the latter so that the drum is maintained in place by them. L is an outlet at the
upper part of the drum L for a purpose hereinafter described.
M is a mould-box indicated diagrammatically on wheels M' and adapted to run
in and out of the cylinder on rails E. E, E are the cylinder covers.
steam-jacketted, and the other, E, is hinged to the cylinder-shell so that it can be
readily opened and shut when the mould-box M passes out of or into the cylinder.
The barrel of the cylinder E may be wholly or partially steam-jacketted or
surrounded by external steam-coils instead of, but preferably in addition to the
internal coils aforesaid.
The process in which the aforesaid cylinder and mould-box, or equivalents are
employed is as follows :-The mould-box M having been filled with the lime and
other components of the artificial stone is run into the cylinder E which is then
closed and filled with water at a temperature of 212° F., and an accumulator or
pump is kept working until a hydraulic pressure of about 60 pounds per square
inch is shewn on the cylinder pressure gauge; the supply of water is then
stopped.
Steam is then let into the heating coils F to raise the temperature of the contents
of the cylinder gradually to between 400° and 450° F., or even higher; this
raising of the temperature should be commenced within one hour after filling the
cylinder with water as described.
It is desirable that the maximum temperature should be reached within five
hours from the time of filling the cylinder with water, and it is to be kept up for
say 30 hours to effect the "setting" of the stone after which the steam is partially
shut off and the water drained out of the cylinder.
The cylinder is then converted into a rapid drying chamber, the steam supply to
the coils being maintained, but regulated to give a temperature of say 200° F. in
the cylinder in order to expel all moisture from the stone. After say 10 hours of
this drying operation, the steam to the coils F is entirely shut off; the cylinder is
opened, and the mould-box taken out and opened. The stone will then be found
to be haid, practically dry, and ready for immediate use in masonry.
It is found that the absorption of water from the cylinder E by the contents of
the mould-box during the slaking process which takes place in the latter during
the first hour, has very little effect in diminishing the volume of the water in the
cylinder, but if any decrease of the volume and pressure of liquid in the cylinder E
should occur, it will be very slight and a few strokes of the supply pump will
restore the original conditions of working. This is the only pumping which need be
done after once the process is begun, whereas hitherto it has been necessary to
maintain a continuous circulation of the liquid contents of the cylinder for the
whole duration of the process.
Any gases formed or given off during the process ascend through the tubular
screws into the drum whence they can be allowed to issue by way of the
outlet L'.
It is an important feature of this process that the air cracks hitherto produced
in the artificial stone are avoided by using in the cylinder E distilled water free of
air and by not permitting the steam used as the heating medium, to have any access
to the cylinder except under confinement in the coils F; thus no air can get to the
contents of the mould-box M.
The power of the water to penetrate the mass is so great in this process that it
is not necessary to provide special holes for access to the mass inside the mould.
I usually use packing along the edges of the mould and find that the unavoidable
leakage at the angles of the box is sufficient to supply the water necessary.
By this particular method I have found it possible to get sufficient moisture at
a high degree of temperature to enable me to use not only various sands and grits,

page_text: but to use chips of marble ground into a powder and with the requisite proportion
of hydraulic lime (say 80 to 85% of marble to 20 or 15% of lime) produce an
artificial marble capable of being polished and of precisely. the same texture,
closeness, specific gravity and appearance as the natural marble.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A method of manufacturing artificial stone in which the components of the
stone are submerged in water under pressure which is deprived of air, and which
is heated and maintained at a high temperature by a heating medium baving no
direct access to either the stone or the water substantially as and for the purpose
described.
2. A method of manufacturing artificial stone and the like in which the
components of the stone are subjected to treatment with and subsequently without
water under pressure substantially as herein before described.
3. A method of manufacturing artificial stone and the like in which the
components of the stone are subjected to treatment with water (either with or
without subsequent treatment without water) under pressure substantially as
hereinbefore described and approximately for the periods and at the temperatures
specified.
4. Artificial marble produced by subjecting a mixture of pulverized or broken
marble with hydraulic lime to heat and pressure in the manner and substantially
as described.
5. In apparatus for the manufacture of artificial stone and the like a cylinder
such as E and its appurtenances substantially as and for the purpose described and
illustrated in Figures 1, 2 and 3 of the accompanying drawings.
Dated LUIS
5th day
WILLIAM OWEN.
Boult & Wade,
Agents for the Applicant.
WILLIAM OWEN.
Boult & Wade,
Agents for the Applicant.