MANUFACTURE OF CEMENT
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said Ludwig Roth at the Office
of the Commissioners of Patents on the 3rd August 1882.
LUDWIG ROTH of Wetzlar in the Kingdom of Prussia, Germany
MANUFACTURE OF CEMENT"
"AN IMPROVED
The hydraulic properties of cement depend mainly upon the presence of Aluminate
and silicate of lime formed by the action of heat.
According to my present invention the necessary Alumina for the formation of
the aluminate of lime is provided by the addition of Bauxite to the other materials,
and the proportion of silicic acid is provided by the addition of a corresponding
addition of quartz, hydrated silicic acid, infusorial earth, furnace slag or other
silicates, while the lime is furnished either in the form of limestone chalk, burnt
lime, or the like. In some cases the addition of a small quantity of dolomite,
oxide of iron, raw soda, alkaline ash, or the like, is necessary as a flux. It is very
essential that the raw materials should be ground to a very fine powder, and be
thoroughly incorporated. After pulverization the raw materials are chemically
examined and their admixture is based on the result of the analysis, while at the
same time it must be taken into consideration whether and how much of any one
or more of the ingredients essential to the purpose to which the cement is to be
applied, is contained in one or more of the other raw materials. Lime, silicic acid
and alumina should, according to the results of numerous analyses, be present in
about the following proportions in a good cement :
58 to 63 per cent
Lime from
Silicic Acid from
Alumina
22 to 26
"
رو
6 to 10
13
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& more,
After
and these proportions should be considered in mixing the raw materials.
mixing, the mass is formed into slabs dried and burnt, and the cement slag thus
obtained is broken up and ground. For grinding mixing and burning the materials
as also for reducing the cement slag, the same apparatus and kilns are employed as
are used for the production of portland cement.

page_text: The Bauxite may be considered as & mixture of hydrate of alumina with
bydrated oxide of iron and silicic acid and contains in a pure state about 60 per
cent of alumina 25 per cent of oxide of iron, 3 per cent of silicic acid and
12 per cent water. It is however generally mixed with earthy constituents and is
consequently very variable in its composition. The free alumina is the constituent
of Bauxite essential for the Cement manufacture; the iron oxide is only of
secondary advantage. Bauxite occurs in the South of France, Calabria, Ireland,
Steyermark, Krain, Wochein (when it is also termed "Wocheinit") and Senegal.
I also include as such a mineral occurring on the Basalt of the Vogelsberg,
Westenwald, &; the composition of which is as follows :-

page_text: In this calculation it is assumed, as shewn, that the sulphur is contained in the
cement, which however is not actually the case. In reality the hydrate of alumina
of the Bauxite combines with the calcic sulphide of the slag to form sulphuretted
hydrogen and aluminate of lime. Consequently the formation of gypsum, which
would be injurious to the cement is prevented.
If it be desired to produce from slag No I a cement having about 10 p.c. of
alumina I mix with
100.61 parts thereof
In producing cement from the Slag (No II (resulting from the smelting of pig
metal for puddling), in view of the high per centage of alumina thereof, I limit
myself to the addition of lime, should the cement not require more than from 8
to 9p.c of alumina. If more alumina be required, I also add in this case a
corresponding quantity of Bauxite. If I add to 98-73 parts of Slag No 1I for
example: 50-00 parts of line or a corresponding greater quantity of limestone.
I obtain 148.73 parts of cement, of the following composition.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Ludwig Roth in the Great Seal Patent Office on the 24th January
1883.
-
LUDWIG ROTH of Wetzlar in the Kingdom of Prussia, Germany.
IMPROVED MANUFACTURE OF CEMENT"
"< AN
The hydraulic properties of Cement depend mainly upon the presence of Aluminate
and Silicate of lime formed by the action of heat
According to my present invention the necessary Alumina for the formation of
the aluminate of lime is provided by the addition of Bauxite to the other materials,
and the proportion of silicic acid is provided by the addition of a corresponding
addition of quartz, hydrated silicic acid infusorial earth, furnace slag or other
silicates, while the lime is furnished either in the form of limestone, chalk, burnt
lime or the like. In some cases the addition of a small quantity of dolomite, oxide
of iron, raw carbonate of soda, alkaline ash or the like is necessary as a flux, but
this may in most cases be dispensed with.
It is very essential that the raw material should be ground to a very fine
powder and be thoroughly incorporated. After pulverization, the raw materials
are chemically examined and their admixture is based on the result of the analysis;
while at the same time it must be taken into consideration whether and how much
of any one or more of the ingredients essential to the purpose to which the cement
is to be applied, is contained in one or more of the other raw materials. Lime,
silicic acid and alumina should, according to the results of numerous analyses, be
present in about the following proportions in a good portland cement:
Lime from 58 to 63 per cent.
Silicic acid from 22 to 26 per cent.
Alumina 6 per cent and more,
and these proportions should be considered in mixing the raw materials. After
mixing, the mass is formed into slabs dried and burnt, and the cement slag thus
obtained is broken up and ground. For grinding, mixing and burning the
materials as also for reducing the cement slag, the same apparatus and kilns are
employed as are used for the production of portland cement.
The bauxite may be considered as a mixture of hydrate of alumina with
hydrated oxide of iron and silicic acid and contains in a pure state about 60 per
cent of Alumina, 25 per cent of oxide of iron, 3 per cent of silicic acid, and 12 per
cent water. It is, however, generally mixed with earthy constituents and is
consequently very variable in its composition. The free alumina is the constituent
of Bauxite essential for the Cement manufacture the iron oxide is only of secondary
advantage. Bauxite occurs in the South of France, in large deposits at les Beaux,
near Avignon, in the south east of Italy (Calabria), at Belfast, Ireland, Steyermark,
Krain, Wochein (whence it is also termed Wocheinit") and Senegal. I also include
as such, a mineral occurring on the Basalt of the Vogelsberg, Westenwald, &c. the
composition of which is as follows —
10

page_text: In order to illustrate the above process by an example, I will take the preparation
of cement from furnace slag, limestone or burnt lime and Bauxite. The com-
position of blast furnace slag is very variable; the following are two characteristic
analyses thereof :-
1
In order to produce cement from the Slag: No I (resulting from the smelting of
pig metal for foundry purposes) I take, for example, the Bauxite of Giessen,
and add to 100 parts of of slag 85 parts limestone or chalk, having 98 p.c of
carbonate of lime and 2 p.c of silicic acid, and 15 parts of Bauxite. After
burning, I obtain from this mixture 158-66 parts of cement of the following
composition:
--
In this calculation it is assumed that one half of the sulphide of calcium con-
tained in the slag combines with the hydrate of alumina of the Bauxite to form
sulphuretted hydrogen and alumniate of lime.
In producing cement from the slag No II (resulting from the smelting of pig
metal for puddling) in view of the high per centage of alumina thereof, I limit
myself to the addition of lime, should the cement not require more than from 8
to 9 p.c. of alumina. If more alumina be required, I also add in this case a
corresponding quantity of Bauxite. If I add to 98.73 parts of Slag No. II, for
example, 50 parts of lime or a corresponding greater quantity of limestone,
I obtain 148-73 parts of cement of the following composition.
As the alumniate of lime possesses valuable hydraulic properties, it is advisable
to add the Bauxite in such proportions that the percentage of alumina shall be
high.
Lastly it is to be observed that it is not absolutely necessary to proportion the
composition of the cement, exactly the same as that of Portland cement, but that
with the described process, a much cheaper and yet very useful cement may be
produced, in taking about the same quantity of Bauxite, but a much smaller
quantity of lime
Having thus described the nature of my invention, and in what manner the same
is to be performed, I claim ;-
The herein described process for the production of cement by burning and
grinding a mixture of Bauxite, or minerals similar to Bauxite, consisting mainly of

page_text: hydrate of alumina hydrated oxide of iron, and silicic acid, with quartz, hydrated
silicic acid, infusorial earth, blast furnace slag or other silicates, and lime, either as.
limestone, chalk, burnt lime or other forms, and with or without admixture of
dolomite, oxide of iron, raw carbonate of Soda, alkali ash or the like as fluxes
In Witness whereof, I the said Ludwig Roth.have hereunto set my hand and
seal this fifteenth day of January in the year of our Lord, one thousand
eight hundred and eighty-three
LUDWIG ROTH.
(L.S.)