Improved Process for the Manufacture of Artificial Sandstone.
Year: 1894

page_text: Date of Application, 2nd July, 1894
Complete Specification Left. 2nd Apr.. 1895-Accepted, 2nd Oct., 1895
PROVISIONAL SPECIFICATION.
Improved Process for the Manufacture of Artificial Sandstone.
I, JACOB PFEIFFER of Kaiserslautern, Rhein Pfalz, (Rhenish Palatinate) in
the Empire of Germany, Councillor of Commerce and Millowner, do hereby
declare the nature of this invention to be as follows:-
That slaked lime, at high temperatures and especially under high pressure, acts
upon quartz-sand, and particularly upon mineral conglomerates containing silicic
acid, in such manner that these materials are converted into a hard stony mass,
well known.
is
The object of this invention is simply to bring about the aforesaid transformation
in the simplest and cheapest possible way, and is effected in the following manner.
The lime which, after being slaked, is to form one of the ingredients of the
subsequently produced artificial stone is first deposited in a layer on the bottom of
the pressure chamber. The materials including the lime slaked on the bottom of
the pressure chamber at a previous operation and which are, at this operation, to be
converted into artificial sandstone, may be placed in a plastic state on frames or
racks of waggons or trucks which are run into the pressure-chamber on suitable
bearers or rails.
The chamber, thus charged, is closed tightly, and then water is turned on,
through the service-pipe, to the lime at the bottom of the said chamber. In
proportion to the slaking of the lime, the temperature and steam-pressure rises
within the chamber so that the plastic masses lying on the frames become converted,
eventually, with the further aid of increased pressure generated by direct heat or
by the introduction of high-pressure steam, into hard stone.
When the high-pressure is relaxed, and as the tension within the cylinder is
lowered, a cock or valve in communication with a reservoir of compressed carbonic
acid gas may be opened. In proportion as the steam condenses within the chamber
the carbonic acid gas gradually replaces it, ultimately permeating the masses to
the rore, and saturating any remaining uncombined surplus of lime within the
artificial sandstone blocks, thereby converting into lime carbonate any remaining
free lime-hydrate and consequently preventing any subsequent change by re-action
in the otherwise still unstable lime. When the blocks are adequately cooled, the
cock or valve is closed and the cylinder opened for the removal of its contents.
The artificial stone blocks, when taken out, are ready for immediate delivery
and use, as the hardening process is absolutely completed and effected.
The fully-slaked lime in the bottom of the chamber is used in preparing the
mortar for the next following or other subsequent operation.
Dated this 2nd day of July 1894.
W. P. THOMPSON & BOULT,
Agents for the Applicant.

page_text: 1, JACOB PFEIFFER of Kaiserslautern, Rhein Pfalz, (Rhenish Palatinate),
Empire of Germany, Councillor of Commerce and Millowner, 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 :-
That slaked lime, at high temperatures and especially under high pressure, acts
upon quartz-sand, and particularly upon mineral conglomerates containing silicic
acid, in such manner that these materials are converted into a hard stony mass, is
well known.
The object of this invention is simply to bring about the aforesaid transformation
in the simplest and cheapest possible way.
In the accompanying drawings is represented the apparatus adapted for carrying
out the invention, in Figure 1 in cross section and in Figure 2 in longitudinal
(vertical) section.
The same consists of one or more cylinders a and a water reservoir communi-
cating with the cylinders by means of a cock r as well as of a carbonic-acid
reservoir c which by means of a cock h can also be put in communication with the
cylinders a.
The materials to be used are very various, and comprise quartz, sand, and every
variety of silicious stone and conglomerates that are found in nature, viz.: silicic
acid and its compounds, i.e., all silicates, so far as they are free from lime and
magnesia; all sands from silicious-stone, quartz, flint, loam and clay, etc. These
materials and the lime mixed with then may be used in the usual or other
proportions, as desired.
The burnt lime required on each occasion when the mortar has to be prepared is
deposited in a layer on a tray a' in the bottom of each pressure cylinder a. The
materials which are to be converted into artificial sand-stone, prepared in a plastic
state may be placed on frames or racks d of wagons or trucks d¹ which are run into
the cylinder a on suitable bearers or rails a².
The cylinder a thus charged is closed tightly, and then water is turned on, through
the service-pipe r, to the lime in the trays a'. In proportion to the slaking of the
lime, the temperature and steam-pressure rise within the cylinders a so that the
plastic masses lying on the frames become converted, eventually, with the further
aid of increased pressure generated by direct heat or by the introduction of high-
pressure steam, into hard stone.
When the high-pressure is relaxed, and as the tension within the cylinder is
lowered a cock or valve h in communication with the reservoir e of compressed
carbonic acid gas may be opened. In proportion as the steam condenses within the
cylinder, the carbonic acid gas gradually replaces it, ultimately thoroughly
permeating the masses and saturating any remaining uncombined surplus of lime
within the artificial sandstone blocks, thereby converting into lime carbonate any
remaining free lime-hydrate and consequently preventing any subsequent change
by re-action in the otherwise still unstable lime. When the blocks are adequately
cooled, the cock or valve his closed and the cylinders a are opened for the removal
of their contents.
The artificial stone blocks, when taken out, are ready for immediate delivery and
use, as the hardening process is absolutely completed and effectual.
The fully-slaked line in the trays a' at the bottom of the cylinder is used in
preparing the mortar for the next following operation.

page_text: 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 1
claim is :-
1. A process for the manufacture of artificial sandstone characterized by the
utilization of the heat and steam-pressure generated during the slaking of lime
(intended to be used in the preparation of the mortar required in a subsequent
conversion-process) such utilization having for its object the transformation into
artificial sandstone blocks of the plastic masses made for the purpose with the lime
resulting from a preceding similar operation.
2. In the process described in Claim 1 supplying compressed carbonic acid gas
to the plastic masses while the latter are being converted into artificial sandstone
blocks for the purpose of converting into lime-carbonate any remaining free
lime-hydrate so that all subsequent change by reaction in the otherwise still
unstable lime is entirely prevented.
Dated this 2nd day of April 1895
BOULT & WADE,
Agents for the Applicant.