Process for the Manufacture of Weather-proof Gypsum Stone or Bricks.
Year: 1896

page_text: Date of Application, 15th June, 1896-Accepted, 1st Aug., 1896
COMPLETE SPECIFICATION.
Process for the Manufacture of Weather-proof Gypsum Stone or
Bricks.
I, PETER KLEBER, Manufacturer, of Saarbrücken in the Empire of Germany,
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 a process for the manufacture of artificial stone or
bricks from gypsum, which shall not be liable to effloresce or to crumble away
under the action of the weather.
In order to produce a plastic mass that does not harden immediately, gypsum is
mixed with a mixture of potash and hydraulic lime.
On further treating the mass with dilute sulphuric acid and gypsum-water, the
following reactions take place-
First, the potash dissolves and combines with the lime to form carbonate of lime
and caustic potash-viz.-Ca(OH), K2 + CO = CaCO3 + 2 KOH.
The carbonate of lime is decomposed by the action of the dilute sulphuric acid,
and carbonic acid is given off; and gypsum is produced,-riz.-CaCO,H, +
SO, CaSO4 + H2O + CO2; while the potash lye is converted by means of
the sulphuric acid into sulphate of potash which dissolves out. In this manner
there is now obtained a plastic mass which does not harden at once, so that it can be
shaped under pressure in moulds. A further treatment with a solution of alum
has for its object to remove any alkali that may still be present, said alkali acting
to decompose the alum to form alumina which itself serves to still further harden
the stone, viz.-AIK, (SO4) + 6 KON = Al, (ON), + 4 K₂SO₁.
This process is carried into practice in the following manner-
10 parts of sifted ashes, potash, and other alkaline carbonates are mixed in the
dry state with 1 part of a mixture consisting of 80 parts of gypsum and 20 parts of
hydraulic lime. The resulting mixture is well worked up together and is stirred
up with a solution composed of saturated gypsum water acidulated with 5% of
sulphuric acid, and is kneaded until there is produced a plastic kneadable mass..
This mass can be employed in the manufacture of stone or bricks which are
produced under the strong pressure of a press in moulds. The raw or "green"
stone or bricks thus produced are dipped into a saturated solution of alum or other
alumina or alum earth which has been acidulated with of sulphuric acid. The
said stone or bricks when dried, are ready for use.
"
Having now particularly described and ascertained the nature of my said inven--
tion, and in what manner the same is to be performed, 1 declare that what I
claim is-
Process for the manufacture of building stone or bricks, according to which,
potash is mixed in the dry state with a mixture of gypsum and hydraulic lime, and
is then made into a plastic mass with saturated acidulated gypsum water, said.

page_text: plastic mass being then pressed in moulds, after which the resulting raw or "green"
stone or bricks are dipped into a saturated solution of alum which has been
acidulated with sulphuric acid.
Dated in 15th da.. of Ton 1906
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.