Process for the Manufacture of Fireproof Building Stones, and for the Production of Cement from the same.
Year: 1898

page_text: Date of Application, 22nd Jan., 1898-Accepted, 14th May, 1898
COMPLETE SPECIFICATION,
A Process for the Manufacture of Fireproof Building Stones, and for
the Production of Cement from the same.
I, PETER KLEBER, of 64, Trierer-Allesstrasse Malatatt-Burbach, Rhine Province,
in the Kingdom of Prussia, Manufacturer, 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:-
This invention relates to the manufacture of building stones or of stones of any
other desired shape, and for the production of cement, and the process is as
follows:-
Burnt lime in lumps is mixed in the proportion of from 1-12 to 1-15 with
quartz or sand stone and then treated in the stone breaker until it is reduced to
the size of hazel nuts, and is then ground finely in a beater grinding mill. The
raw materia! reduced to the size of grains of sand is thoroughly mixed together in
mixing machines and a part of the burnt lime becomes slaked by reason of the
natural moisture of the sand. In the mixing machine the raw material is
sprinkled with dilute hydrochloric acid by means of a pipe arranged over it at a
suitable place, and the materials are intermixed as intimately as possible. The
water of the hydrochloric acid first acts at once to slake the lime, whilst the hydro-
chloric acid itself combines with a portion of the lime to form chloride of calcium,
and also partly decomposes the silicates contained in the lime or in the sandstone,
the result being that chlorides of alumina, iron oxide, magnesia, etc. are formed
and gelatinous silicious acid is separated. All these substances form together a
plastic mass which can be readily moulded or pressed. From the mixing machine
the material is then placed into suitable moulds in which it is shaped into building
stones of standard size or any other kind of article.
The stones thus shaped are subjected to a hardening process. The pressed stones
are placed upon specially constructed cars and are pushed along rails into recep-
tacles made of thick sheet iron. These receptacles, for the purpose of withstanding
high pressure, are preferably made round, and are so dimensioned as to be capable
of holding 3600 to 4000 stones of standard size. When a receptacle has been
charged with the stones, a suitable quantity of considerably diluted hydro-chloric
acid is run on to the bottom of the same, and the receptacle is closed in steam-tight.
Then the liquid is heated until a pressure up to 7 atmospheres or a temperature of
160 to 179 degrees Centigrade obtains in the vessel. After the lapse of a few
hours the stones acquire very considerable hardness.
In this operation two processes are effected. On one hand the chloride of cal-
cium which is formed from the hydro-chloric acid and the lime, combines with the
slaked lime that is still present, to form an oxychloride of calcium. On the other
hand, the silicic acid separated from the silicates by the hydro-chloric acid com-
bines with the lime to form a silicate. It is, however, not impossible that the
silicic acid which has not been split up may also aid in forming the silicate. The
longer the heating of the stones is continued, the more perfectly effected are these
re-actions and the harder the stones become. It is to be noted as being especially