IMPROVEMENTS IN THE MANUFACTURE OF CEMENT AND ARTIFICIAL STONE
Year: 1878

page_text: $$
LETTERS PATENT to Frederick Ransome, of Lower Norwood, in the County of
Surrey, for the Invention of IMPROVEMENTS IN THE MANUFACTURE OF
CEMENT AND ARTIFICIAL STONE."
Sealed the 13th May 1879, and dated the 16th November 1878.
PROVISIONAL SPECIFICATION left by the said Frederick Ransome at the
Office of the Commissioners of Patents on the 16th November 1878.
FREDERICK RANSOME, of Lower Norwood, in the County of Surrey. "IMPROVE-
MENTS IN THE MANUFACTURE OF CEMENT AND ARTIFICIAL STONE."
This Invention has for its object improvements in the manufacture of cement
and artificial stone. Heretofore Portland cement has commonly been made from
chalk, or lime stone and clay intimately mixed together, and subsequently burned
in a kiln. The clay used in the manufacture of this cement has ordinarily been a
river clay, usually clayey river mud. Such cements as heretofore made have for
some purposes the disadvantage that after they have been used and become set and
hardened they are of a brownish color, which deepens considerably when their
surface is exposed to wet. This is a serious disadvantage when the cements are
required to be used in the manufacture of artificial stone, or for giving an exterior
coating to the walls of buildings, and for many other purposes where it is required
that the cement shall not be liable to changes of colour. I have discovered that by *
exposing a mixture of previously washed kaolin and carbonate of lime in the form
of marble or other suitable limestone to a strong heat, especially when contained in
retorts or muffles, or when otherwise protected from the direct action of the heated
products of combustion in the furnace or kiln, that an uncolored cement is obtained,
and that such cement after it has been used and has become set and hardened will
not be liable to such discoloration.
For some purposes I mix soluble silica with the above mentioned materials
previous to burning. The soluble silica may be such as is found in certain well
known mineral beds, or it may be artificially prepared.

page_text: Any desired tint or color may be given to the cement by mixing with it various
coloring materials after it has been ground and prepared for use.
I also produce a cement which is eminently hydraulic by the treatment of lime
which contain silica, such for instance as that known as lime of teil with alumina
in the form of hydrate, or any of its salts, preferably a solution of sulphate of
alumina.
I also produce cement from the artificial sand which is now. prepared in large
quantities from slag produced in blast furnaces. I grind the slag sand with chalk
or other calcareous mineral, and in some cases I also add soluble silica.
I burn these materials together, as is usual in the manufacture of cement.
These cements are also applicable for the production of moulded articles of
artificial stone.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frederick Ransome in the Great Seal Patent Office on the 16th May
1879.
FREDERICK RANSOME, of Lower Norwood, in the County of Surrey.
MENTS IN THE MANUFACTURE OF CEMENT AND ARTIFICIAL STONE."
"IMPROVE-
This Invention has for its object improvements in the manufacture of cement and
artificial stone. Heretofore Portland cement has commonly been made froin chalk,
or limestone and clay intimately mixed together, and subsequently burnt in a kiln.
The clay used in the manufacture of this cement has hitherto been ordinary impure
clays, more especially such as that obtained from the alluvial deposits of the Medway
and the Thames. Such cements as heretofore made have for some purposes the
disadvantage that after they have been used and become set and hardened they are
of a brownish color, which deepens considerably when their surface is exposed to
wet. This is a serious disadvantage when the cements are required to be used in
the manufacture of artificial stone, or for giving an exterior coating to the walls of
buildings, and for many other purposes where it is required that the cement shall
not be liable to changes of color. I have discovered that by exposing a mixture of
previously washed kaolin and carbonate of lime in the form of marble or other
suitable limestone to a strong heat, especially when contained in retorts or muffles,
or when otherwise protected from the direct action of the heated products of com-
bustion in the furnace or kiln, that an uncolored cement is obtained, and that such
cement after it has been used and has become set and hardened will not be liable to
such discoloration.
For some purposes I mix soluble silica with the above mentioned materials previous
to burning. The soluble silica may be such as is found in certain well known mineral
beds, or it may be artificially prepared.
Any desired tint or color may be given to the cement by mixing with it various
coloring materials after it has been ground and prepared for use.
I prefer to conduct the manufacture in the following manner :-
I grind together in the manner ordinarily practiced by makers of Portland cement
china clay and chalk, or preferably, where it can be obtained at a reasonable cost,
white marble. These materials are employed advantageously in the proportion of
one part by weight of china clay to three parts of the chalk or marble. As in the
manufacture of Portland cement it is essential that the materials should be finely
ground and intimately mixed.
As china clay is usually somewhat deficient in silica I supply this deficiency by
the addition during the process of manufacture of soluble silica, such for example as
that found in the natural beds near Farnham, or preferably from the deposits in the
New England States, U. S. A., so that relative proportions of the lime, alumina, and
silica shall after burning be about,—
Lime
Alumina
Silica
60 parts
.12
22
"
"

page_text: on the banks of the Rhone), or other like lime containing silica in large proportion
for use as mortar or in concrete or as a cement, I slake or gauge the lime with
this solution of alumina in lieu of water, and thereby supply to the lime in an active
form the alumina which it requires to compensate the silica.
In place of employing the solution of a salt of alumina hydrate of alumina sus-
pended in water may be employed in like proportion.
I also produce cement from the artificial sand which is now prepared in large
quantities from slag produced in blast furnaces, and known commercially as slag
sand. I grind the slag sand with chalk or other calcareous mineral, and in some
cases I also add soluble silica. I burn these materials together, as is usual in the
manufacture of cement.
The proportions in which I prefer to use the ingredients are as under,―
Carbonate of lime, from 1 to 2 parts
Slag sand
-
1
"
In the burning operation somewhat less heat will be required than in burning the
ordinary ingredients of Portland cement.
These cements are also applicable for the production of moulded articles of artificial
stone,
The cements are mixed with sand and reduced with water to a proper consistency
for moulding.
Having thus described, the nature of my said Invention and the manner of per-
forming the same, I would have it understood that I claim,―
First. The manufacture of a white or artificially tinted cement. from a mixture
of kaolin or china clay and chalk or marble, with or without other materials,
by burning such mixture in muffle kilns or retorts without contact with the fuel.
Second. The treatment of lime of tiel and like limes containing a large propor-
tion of silica with the solution of a soluble salt of alumina, or with alumina in the
form of hydrate.
Third. The manufacture of cement by burning a mixture of slag sand and car-
bonate of lime.
Fourth. The manufacture of cement and artificial stone, substantially as
described.
In witness whereof, I, the said Frederick Ransome, have hereunto set my
hand and seal, this Fifteenth day of May, in the year of our Lord One
thousand eight hundred and seventy nine.
}