Improved Process of Preparing, the Raw Materials for the Manufacture of. Calcareous Sandstone.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improved Process of Preparing, the Raw Materials for the
Manufacture of. Calcareous Sandstone.
I, WILHELM SCHWARZ, of 46, Weinberg Street, in Zurich, Switzerland,
Chemist, do hereby declare the nature of this invention to be as follows:-
The manufacture of calcareous sandstone has not yet reached such a state of
development that an absolutely uniform product of good quality is always ob-
tained. Experiments have proved that the cause of the frequent failure, lies
in the different condition or state of the sand employed in said manufacture.
Sometimes the sand is too moist and at other times it is too dry; sometimes
the mixture of sand and lime is a wet and pulpy mass badly suited for being
pressed, and at other times the pressed mass in consequence of insufficiently
slackened lime having been used in the composition after setting shows rents and
irregularities owing to the after-slacking of the line when the mass hardens.
Owing to the natural moisture of the same, and to the combined effects of this
moisture and that of the atmosphere, there occurs a certain combination between
the sand and the lime, but the extent of that combination cannot be positively
determined because of the unknown quantity of moisture present. It is, there-
fore, extremely difficult or even impossible to accurately determine how much
moisture (water or steam) must still be added to ensure the formation of a
perfect uniform silicate. The quantity of the moisture should be neither too
great or too small, because in either case an unsatisfying product is attained;
this can be avoided only if means are taken to exactly determine the quantity
of moisture already present or to be added, and thus to start the process from a
constant and fixed point.
According to this invention such point is obtained in the simplest manner
imaginable by drying the sand and the lime before they are mixed, so that the
unknown amount of moisture is completely removed, and thus eliminated from
the process. The latter may now be carried out accurately and the result of
the process depends no longer upon skill and practical experience, but solely on
calculation or formula, the result being calcereous sandstones of an unvarying
condition and highest quality.
In carrying the improved process into practice the sand is first dried, prefer-
ably in a vacuum-pan provided with revoluble wings or other means for sub-
sequently mixing the sand with the lime and the whole with the necessary
amount of water steam of moisture. A vacuum-pan is preferred to other means
for drying because that is the most economical. After the sand has been com-
pletely dried the lime is added which has preferably been previously dried in a
vacuum fan or other apparatus, or it may be dried only in the vacuum-pan con-
taining the dried sand and the complete mixture of the two dried substances is
then effected still under vacuum, whereupon the moisture preferably steam, is
introduced into the pan and mixed with the sand and lime, until the formation
of the silicate is completely finished. The mass produced in this way is a soft

page_text: pulp of perfect uniformity that may easily be pressed into moulds of any desired
shape so as to be made into stones blocks or forms of corresponding configuration.
Maintaining the vacuum during the drying as well as during the mixing
operation is especially advantageous, because then any injurious influence of
the more or less damp atmospheric air is completely prevented, and the formation
of the silicate by the intimate contact of the substances in question is greatly
facilitated.
Dated 101.
1000
BOULT, WADE & KILBURN,
Agents for the Applicant.
Improved Process of Preparing the Raw Materials for the
Manufacture of Calcareous Sandstone.
I, WILHELM SCHWARZ, of 46, Weinbergstrasse, Zurich, in the Republic of
Switzerland, Chemist, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
The manufacture of calcareous sandstone has not yet reached such a state of
development that an absolutely uniform product of good quality is always ob-
tained. Experiments proved that the cause of the frequent failure, lies
in the different condition or state of the sand employed in said manufacture.
Sometimes the sand is too moist and at other times it is too dry; sometimes
the mixture of sand and lime is a wet and pulpy mass badly suited for being
pressed, and at other times the pressed mass in consequence of insufficiently
slackened lime having been used in the composition after setting shows rents and
irregularities owing to the after-slacking of the lime when the mass hardens.
Owing to the natural moisture of the sand and to the combined effects of this
moisture and that of the atmosphere, there occurs a certain combination between
the sand and the lime, but the extent of that combination cannot be positively
determined because of the unknown quantity of moisture present. It is therefore
extremely difficult or even impossible to accurately determine how much moisture
(water or steam) must still be added to ensure the formation of a perfect, uniform
silicate. The quantity of the moisture should be neither too great nor too small,
because in either case an unsatisfying product is attained; this can be avoided
only if means are taken to exactly determine the quantity of moisture already
present or to be added, and thus to start the process from a constant and fixed
point.
According to this invention such point is obtained in the simplest manner imagin-
able by thoroughly drying the sand and the lime before they are mixed, so that the
unknown amount of moisture normally present in it is completely removed and
thus eliminated from the process. The latter may now be carried out accurately
and the result of the process depends no longer upon skill and practical experience,
but solely on calculation or formula, the result being calcareous sandstones of an
unvarying condition and of the highest quality.
In carrying the improved process into practice the sand is first dried, prefer-
ably in a vacuum-pan provided with revoluble wings or other means for sub-
sequently mixing the sand with the lime and the whole with the necessary
amount of water, steam or moisture.
A vacuum-pan is preferred to other means for drying because that is the most

page_text: economical. After the sand has been completely dried the lime is added which
has preferably been previously dried, in a vacuum-pan or other apparatus, or it
may be dried only in the vacuum-pan containing the dried sand, and the com-
plete mixture of the two dried substances is then effected still under vacuum,
whereupon the moisture, preferably steam, is introduced into the pan and mixed.
with the sand and the lime, until the formation of the silicate is completely
finished. The mass produced in this way is a soft pulp of perfect uniformity
that may easily be pressed into moulds of any desired shape so as to be made into
stones blocks or forms of corresponding configuration.
Maintaining the vacuum during the drying as well as during the mixing
operation is especially advantageous, because then any injurious influence of
the more or less damp atmospheric air is completely prevented, and the formation
of the silicate by the intimate contact of the substances in question is greatly
facilitated.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. The process of preparing the raw-materials for the manufacture' of cal-
careous sandstone, characterized by drying the substances in order to remove any
moisture which they may contain, before the moisture necessary to obtain a
mouldable mass is added, substantially as described.
2. The process of preparing the raw-materials for the manufacture of calcareous
sandstone, characterized by drying the substances under a vacuum, before the
moisture necessary to obtain a mouldable mass is added, substantially as de-
scribed.
3. The process of preparing the raw-materials for the manufacture of calcareous
sandstone, characterized by drying the substances under a vacuum, and mixing
them thereafter together also under a vacuum, before the moisture necessary to
obtain a mouldable mass is added substantially as described.
4. The process of preparing the raw-materials for the manufacture of calcareous
sandstone, consisting in drying the sand, adding dried lime, mixing the sand and
the lime, adding to the mixture a predetermined quantity of moisture, and
mixing again so as to obtain a mouldable mass, substantially as described.
5. The process for preparing the raw-materials for the manufacture of cal-
careous sandstone, consisting in drying the sand under a vacuum, adding dried
lime and mixing both substances whilst containing the vacuum, adding to the
mixture a predetermined quantity of moisture, and mixing again so as to
obtain a mouldable mass substantially as described.
Dated this 26th day of March 1900
BOULT, WADE & KILBURN,
Agents for the Applicant.