IMPROVEMENTS IN THE MANUFACTURE OF THE SALTS, CARBONATES, AND HYDRATES OF BARYTA AND STRONTIA, AND ALSO FOR IMPROVED MODES OF MAKING BARYTA AND STRONTIA CAUSTIC
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Edward Thomas Hughes at the
Office of the Commissioners of Patents, with his Petition, on the
14th March 1873.-A communication from abroad by Louis
Gustave Ghilain Daudenart and Edmond Verbert, of 34, Rue du
Progrès, Schaerbeek, Brussels.
I, EDWARD THOMAS HUGHES, of the Firm of Hughes and Son, Patent
Agents, 123, Chancery Lane, London, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF THE SALTS,
CARBONATES, AND HYDRATES OF BARYTA AND STRONTIA, AND ALSO FOR IMPROVED
MODES OF MAKING BARYTA AND STRONTIA CAUSTIC," a communication to me
from abroad by Louis Gustave Ghilain Daudenart and Edmond Verbert,
of 34, Rue du Progrès, Schaerbeek, Brussels (to be as follows):
In order to produce the carbonates of baryta and strontia according
to this process I take alkaline earthy chlorides, not only because they
are very suluble and that sulphates of baryta and strontia are obtained
from them with facility and economy, but also that by means of this
process I obtain free hydrochloric acid at the same time that the
carbonates of the alkaline earths are produced.
The reactions which take place are explained by the following
equations made with regard to the obtaining of carbonate of baryta,

page_text: and the equations are the same for carbonate strontia, it being only
necessary to take chloride of strontium instead of chloride of barium.
and strontia in their material state.
Secondly, by the action of the same acid on the sulphurets of barium
and strontium procured by the decomposition of the sulphates of these
bases by carbon.
Thirdly, by the reciprocal action indicated by Monsieur Kuhlmann
between the sulphates of baryta or strontia, carbon, and the chloride of
manganese, or by any other method by which they are dissolved in
water to 12 or 15 degrees Baumé. The solution thus obtained whether
the chloride of barium or the chloride of strontium is mixed with hydrate
of magnesia in any suitable apparatus which can be afterwards closed.
This mixture is kept in continual agitation in the closed apparatus and
subjected to the action of a current of carbonic acid, which gas is
absorbed by the magnesia forming a carbonate of this base. In principle
the carbonate of magnesia decomposes the alkaline earthy chlorides,
but the employment of an excess of carbonic acid causes the decom-
position to be more rapid, and at the same time the carbonates of the
alkaline earths are obtained, especially those of baryta and strontia, free
from carbonate of magnesia, a result that cannot be obtained by the
mixture of the chlorides with the carbonate of magnesia only. This
carbonate dissolves in water assisted by an excess of carbonic acid, and
thus a bicarbonate of magnesia is formed, and besides this a double
decomposition rapidly takes place between the alkaline carthy chlorides
and the bicarbonate of magnesia, carbonate of baryta is precipitated, the
carbonic acid is regenerated, and the liquor holds in solution chloride of
magnesium as expressed by the following notation :
CIBa+(CO®)*MgO+Aq.=CO*BaO+CIMg+CO+Aq.

page_text: Carbonate of magnesia being but little soluble in carbonic acid, or in
other words the solubility in water of the bicarbonate of magnesia being
feeble, it was conceived that the current of carbonic acid should be
made to pass for a much longer time than would be required for the
simple carbonation of magnesia.
It is evident that the carbonation can be effected in any special or
distinct apparatus, and variations of minor importance may be made in
the manipulation, but the process before described is preferred on account
of its simplicity.
In practice the treatment of the alkaline earthy chlorides by magnesia
and carbonic acid should consist of two operations.
In the first the magnesia is in excess, which gives when the reaction
is terminated a liquor containing exclusively chloride of magnesium,
which is decanted and a precipitate obtained consisting of a carbonate
of the alkaline earth, and the magnesia employed in excess in a
carbonated state.
In the second operation an excess of alkaline earthy chloride is found
on the precipitate, that is, a quantity of the chloride equal to that
previously used augmented by a little in addition to what is necessary
for the neutralization of the excess of the carbonate of magnesia. By
the action of the carbonic acid the excess of the carbonate of magnesia
is transformed into chloride of magnesium and is replaced in the
precipitate by an equivalent quantity of carbonate alkaline earth, the
final result being carbonate of baryta or strontia which is obtained in a
pure state after a series of washings. The liquor after this second
operation is a mixture of chloride of magnesium and of alkaline earthy
chloride, the latter being in excess should be again used as it is superior
to that employed in the first operation, and by means of known reagents
and tests it is to be ascertained,―
First, that the liquor of the alkaline carthy chloride employed the
first time contains only chloride of magnesium when the reaction has
terminated.
And secondly, that the precipitate after the second operation washed
and dissolved in hydrochloric acid does not contain any magnesia. The
liquors which only contain chloride of magnesium are concentrated by
evaporating to 44 or more degrees Baumé, and are then passed into the
crystallizers, or if allowed to cool they become hard masses which are

page_text: acid revivines the magnesia according to the following equation :
↑
CIMg+HO=CIH+MgO.
It is of importance to remark that the hydrated chloride of magnesium
calcined at a low red heat in a reverbatory furnace or in crucibles is
not completely decomposed; one-fifth escapes decomposition by the
simple disengagement of a part of the water it contains, besides all the
magnesia formed and submitted in this operation to a heat above
300 degrees Centigrade is when cold in an unfavourable condition for
absorbing carbonic acid and it is hydrated with such slowness as to be
incompatible with a rapid revivification of the carbonate of magnesia, and
it is upon the revivification that the whole of our manufacture is based.
Hydrated chloride of magnesium submitted to the action of a current
of steam superheated to about 300 degrees Centigrade, without pressure,
becomes completely decomposed, and is in the condition to be rapidly
hydrated and carbonated.
To manufacture caustic baryta and strontia from their carbonates by
our process we mix the carbonate of baryta or strontia with carbon or
chalk, and heat the mixture, whether subjected to the action of 2
superheated steam or not, in a regenerating or reverbatory furnace,
which process is applicable not only to the carbonates of baryta and
strontia manufactured as before described, but also to the carbonates of
baryta and strontia in their natural state or produced in any other way,
and we also employ the furnaces for the decomposition of all salts that 2
require a high temperature, especially the sulphates of baryta and
strontia mixed with carbon. By these means we obtain such a
temperature that the carbonates of baryta and strontia whether mixed
with carbon or submitted to the action of superheated steam are rapidly
decomposed with great facility and therefore economically.