Improvements in the Process of and Appliances for Producing Artificial Stone.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Process of and Appliances for Producing
Artificial Stone.
I, WILHELM OLSCHEWSKY, of 31, Kessel Street, Berlin, in the Empire of
Germany, Factory Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention relates to the production of that kind of artificial stone commonly
called lime sandstone employed for walls, roofing tiles, slop stones, paving flags,
and the like which is composed of an admixture of lime and sand subsequently
hardened by moisture and heat as for example by steam in a closed vessel.
In carrying my improvements into effect the following procedure is adopted:
The lime is first thoroughly slaked. To mix it forthwith in that condition with
sand would give a mixture of far too plastic and soft a composition to resist the
pressure employed in moulding it into pieces of the desired form. Further the
moulded parts would fall to pieces on account of the excess of moisture in them
when exposed to the action of the steam employed for hardening them. To avoid
these drawbacks therefore the slaked lime is according to my improvements first
freed from the excess of moisture in a suitable drying appliance and is then mixed
with sand in the desired proportions. Or the slaked lime may be at once mixed
with the sand and the mixture dried until the excess of moisture is removed and
sufficient only remains to enable the mixture to be moulded into the required
forms. In either case the drying operation has this effect that the stones formed
from the mixture may be subsequently hardened without disintegration or fracture
when exposed to steam.
For some articles as for example roofing tiles it may be necessary to work
the mixture of slaked lime and sand in a very moist state, and in this case
the moulded pieces are first dried before being exposed to the action of the steam
in the closed vessel, and it is advisable to take precautions to have the
air employed for this purpose as free from carbonic acid as possible.
In order to obtain the lime as dry as possible (and yet thoroughly slaked) so that
it can be mixed at once with the sand which should be just as moist as when
obtained from the sand pit the following procedure is preferred. The carriages
on which the moulded pieces are conveyed for hardening into the steam vessel are
fitted with an open work platform or grating with a receiver below it containing
the lime to be slaked. The moulded pieces to be hardened are placed on the
openwork platform and the carriage is run into the steam vessel which is then
hermetically closed. Steam is then admitted to the vessel and meeting the
cold moulded pieces condenses, and the water of condensation drips through the open-
work platform upon the lime in the receiver below. In this way the lime is gradually
supplied with water in an uniform distribution and at a high temperature and
the water on account of its high temperature and notwithstanding its relatively
small quantity slakes the lime thoroughly. The lime moreover when withdrawn
from the steam vessel is hot, and the excess of moisture is eliminated from it by

page_text: evaporation. In this manner a sufficiently dry and thoroughly slaked lime is
obtained which mixed with sand of pit moisture produces a mixture which is very
suitable for the production of moulded stones and the like, and which may be
exposed to the direct action of steam without being disintegrated or fractured.
Dated this 28th day of July 1898.
H. B. BARLOW & GILLETT
Agents for Applicant.
Improvements in the Process of and Appliances for Producing
Artificial Stone.
I, WILHELM OLSCHEWSKY, of 31, Kessel Street, Berlin, in the Empire of
Germany, Factory Engineer, 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:-
My invention relates to the production of that kind of artificial stone commonly
called lime-sandstone employed for walls, roofing tiles, slopstones, paving flags
and the like which is composed of an admixture of lime and sand subsequently
hardened by moisture and heat as for example by steam in a closed vessel.
In carrying my improvements into effect the following procedure is adopted:
The lime is first thoroughly slaked. To mix it forthwith in that condition with
sand would give a mixture of far too plastic and soft a composition to resist the
pressure employed in moulding it into pieces of the desired form. Further the
moulded parts would fall to pieces on account of the excess of moisture in them
when exposed to the action of the steam employed for hardening them. To avoid
these drawbacks. therefore, the slaked lime is, according to my improvements, first
freed from the excess of moisture in a suitable drying appliance and is then mixed
with sand in the desired proportions. Or the slaked lime may be at once mixed
with the sand and the mixture dried until the excess of moisture is removed and
sufficient only remains to enable the mixture to be moulded into the required
forms. In either case the drying operation has this effect, that the stones formed
from the mixture may be subsequently hardened without disintegration or fracture
when exposed to steam.
For some articles, as for example, roofing tiles, it may be necessary to work the
mixture of slaked lime and sand in a very moist state, and in this case, the moulded
pieces are first dried before being exposed to the action of the steam in the closed
vessel, and it is advisable to take precautions to have the air employed for this
purpose as free from carbonic acid as possible.
In order to obtain the lime as dry as possible (and yet thoroughly slaked) so that
it can be mixed at once with the sand which should be just as moist as when
obtained from the sand pit the following procedure is preferred. The carriages
on which the moulded pieces are conveyed for hardening into the steam vessel are
fitted with an openwork platform or grating with a receiver below it containing
the lime to be slaked. The moulded pieces to be hardened are placed on the
openwork platform and the carriage is run into the steam vessel which is then
hermetically closed. Steam is then admitted to the vessel and meeting the
cold moulded pieces condenses, and the water of condensation drips through the open-
work platform upon the lime in the receiver below. In this way the lime is gradually
supplied with water in an uniform distribution and at a high temperature and
the water on account of its high temperature and notwithstanding its relatively
small quantity slakes the lime thoroughly. The lime moreover when withdrawn

page_text: from the steam vessel is hot, and the excess of moisture is eliminated from it by
evaporation. In this manner a sufficiently dry and thoroughly slaked lime is
obtained which mixed with sand of pit moisture produces a mixture which is very
suitable for the production of moulded stones and the like, and which may be
exposed to the direct action of steam without being disintegrated or fractured.
The accompanying sheet of drawings shows the details of the above described
appliances.
Figure 1 is a cross section, Fig. 2 a longitudinal section, and Figs. 3 and 4
sectional plans of a suitable arrangement of apparatus for the purposes of my
invention.
The arrangement consists of a carriage having preferably the shape of a railway
platform truck so constructed and arranged that the moulded pieces to be hardened
and the lime to be slaked can by it be conveyed simultaneously into the steam
vessel. The platform of the carriage consists of bars arranged side by side like a
grating and joined at the ends by cross bars to a frame which may be removed when
required from the carriage. A box of sheet tin or other suitable material forms
a receiver for the lime and is fitted into the lower frame work which is carried down
between the axles of the carriage wheels in order to increase the containing
capacity. The openwork platform is made as wide as practicable in order to
utilize the full width of the steam vessel and enable a full load of moulded pieces
and lime to be introduced. The distance between the rails upon which the
carriage wheels run, however, must be kept narrow on account of the curved cross
section of the steam vessel into which the rails have to be continued. The
carriage wheels, therefore, lie back considerably as compared with the width of the
carriage.
In order to fix the axle boxes to the frame and as a support to the box k, the
longitudinal carriers of the lower frame are connected by means of cross stays g
and a second pair of longitudinal carriers t¹ are secured to these which serve for
supporting the carriage upon the axle boxes.
The steam vessel, Fig. 1, is fitted with a loose front plate and with a pipe to which
are secured two branch pipes 7 and which are each controlled by a valve.
The pipe communicates with the steam generator for the supply of high pressure
steam of a correspondingly high temperature.
The pipe communicates with a boiler for producing low pressure steam of a
correspondingly lower temperature, and where a steam engine is available, the
exhaust steam might be supplied through the pipe. The box k is filled after taking
off the grating with the lime to be slaked, then the grating is replaced and upon
it are placed the moulded pieces leaving spaces between them. The carriage,
loaded in this manner, is run into the steam vessel which is then hermetically
sealed. The valve of the pipe is opened and low pressure steam, having more or
less humidity flows into the steam vessel, and meeting the cold moulded pieces
condenses and the water of condensation drips through the spaces between the
pieces and through the open work platform upon the lime in the box k and slakes it.
After a sufficient time, which may be determined by experiment, the pipe is closed
and the pipe opened and the high pressure steam enters the steam vessel to
complete the hardening process.
When the carriage has been withdrawn at the conclusion of the process the
moulded pieces will be found completely hardened, and the lime thoroughly slaked,
hot, and with the excess of moisture eliminated from it by evaporation, and in a
suitable condition for making a further supply of moulded stones.
As a rule the steam vessel is made of such a length that several carriages can be
wheeled into it at the same time.
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 herein described process for making artificial stone, called lime sand

page_text: stone, which consists in mixed lime previously slaked with sand and drying the
mixture prior to moulding the same into pieces of suitable shape and then
hardening the moulded pieces by steam.
2. The process covered by Claim 1 but varied by drying the slaked lime before
its mixture with the sand.
3. The process covered by Claim 1 but varied by drying the moulded pieces
before exposing them to the hardening process..
4. The herein described apparatus for carrying out the processes claimed said
apparatus consisting of a carriage having an openwork platform or grating for
carrying the moulded pieces into the steam vessel and below the grating a box k
to contain the lime for the next set of pieces to be slaked by the water of condensa-
tion dripping from the moulded pieces during the hardening process in the steam
vessel substantially as set forth.
Dated this 24th day of April 1899.
H. B. BARLOW & GILLETT,
Agents for Applicant, 17, St. Ann's Square, Manchester.