A New or Improved Process for the Recovery of the Sulphurous Acid used to Enrich Phosphatic Chalk.
Year: 1899

page_text: Date of Application, 7th Mar., 1899.
Complete Specification Left, 2nd Nov., 1899-Accepted, 6th Jan.,
'
1900
A New or Improved Process for the Recovery of the Sulphurous
Acid used to Enrich Phosphatic Chalk.
We, CHARLES RANSON and HENRI GOUTHIÈRE, both of 48, Boulevard Haussmann,
Paris, in the Republic of France, Engineers, do hereby declare the nature of this
invention to be as follows:-
Phosphatic chalk such as found in large seams or layers in France and Belgium can
be utilized in- the trade by increasing its yield in phosphate of lime while removing
the carbonate of lime. This mode of proceeding however can only be sufficiently
remunerative provided the sulphurous acid used for this purpose can be recovered.
This invention has for its object the fulfilment of such purpose.
1. When phosphatic chalk-finely subdivided by the aid of sulphurous acid-is
subjected to treatinent, there is produced with the carbonic acid which is freed and
can be recovered, a more or less concentrated solution of bisulphite of lime and an
insoluble residuum which consists chiefly of phosphate of lime.
According to this invention the recovery of the sulphurous acid is carried out in
the following manner:
2. The bisulphite of lime is divided in two parts, one of which is heated in order
to release half its contents of sulphurous acid, the residuum being sulphite of lime.
The reaction is explained by the following formula:
One quarter of the sulphurous acid used is thus recovered, while another quarter is
0 contained in the sulphite of lime remaining as a residuum.
3. The sulphite of lime is now mixed with powdered coal or charcoal and
introduced into a reverbatory furnace where the whole is highly heated whilst
stirring. There is thus produced in accordance with the following formula:
sulphide of calcium, mixed with a small quantity of unconsumed carbon and of
sulphite which has not been converted into sulphide. The conversion of the sulphite
into sulphide is easily effected. The sulphite of lime decomposes spontaneously as
soon as heated to a dark red temperature into sulphide and sulphate, the latter
requiring carbon to be converted into sulphide.
4. A sufficient quantity of water being added to the calcic sulphide thus obtained
and carbonic acid being brought into action (which acid was left at disposal after the
first treatment) sulphide of hydrogen becomes separated and carbonate of lime is
formed.
-
CaS+H,O + CO₂ = H₂S + CO₂Ca.
CaS+H,O+CO₂ = H₂S + CO₂Ca.

page_text: subjected to treatment. The sulphide of hydrogen previously obtained and
containing one quarter of the sulphurous acid is mixed therewith. A precipitate is
formed, which is a spongy deposit of sulphur; there is obtained moreover
hyposulphite of lime, a salt which is readily soluble in water. The reaction is set
forth in the formula:
This deposit being dried and burned, a quarter of the sulphurous acid is again obtained
besides a residuum consisting of sulphite of lime which as regards its yield in
sulphur corresponds exactly to one quarter of the sulphurous acid. This residuum
is mixed with the sulphite of lime mentioned under treatment No. 3 and is treated
according as therein described. The mixture to be treated in this operation contains
throughout the whole process an increasing yield in sulphur which will be removed
by treatment No. 5. In this wise, the whole of the sulphurous acid used will be
recovered in a regular manner.
1000
CRUIKSHANK & FAIRWEATHER,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agents for the Applicants.
A New or Improved Process for the Recovery of the Sulphurous
Acid used to Enrich Phosphatic Chalk.
We, CHARLES RANSON and HENRI GOUTHIERE, both of 48, Boulevard Haussmann,
Paris, in the Republic of France, Engineers, 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:—
Phosphatic chalk such as found in large seans or layers in France and Belgium
can be utilized in the trade by increasing its yield in phosphate of lime while
removing the carbonate of lime. This mode of proceeding however can only be
sufficiently remunerative provided the sulphurous acid used for this purpose can
be recovered.
This invention has for its object the fulfilment of such purpose.
1. When phosphatic chalk-finely subdivided by the aid of sulphurous acid-is
subjected to treatment, there is produced with the carbonic acid which is freed
and can be recovered, a more or less concentrated solution of bisulphite of lime and
an insoluble residuum which consists chiefly of phosphate of lime. According to this

page_text: invention the recovery of the sulphurous acid is carried out in the following
manner :-
2. The bisulphite of lime is divided in two parts, one of which is heated in order
to release half its contents of sulphurous acid, the residuum being sulphite of lime.
The reaction is explained by the following formula:
One quarter of the sulphurous acid used is thus recovered, while another quarter
is contained in the sulphite of lime remaining as a residuum.
3. The sulphite of lime is now mixed with powdered coal or charcoal and introduced
into a reverbatory furnace where the whole is highly heated whilst stirring. There
is thus produced in accordance with the following formula:

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
The process for recovering the sulphurous acid used to enrich phosphatic chalk
consisting in decomposing by the aid of heat the bisulphite of lime left, after the
removal of the carbonate of lime from the crude rock, (1st. reaction) down to half its
quantity into sulphurous acid and sulphite of lime (2nd. reaction); in converting the
latter, by heating it to incandescence with carbon, into sulphide of calcium
*(3rd! reaction) and in converting the latter-by a treatment with the carbonic acid
freed during the first treatment-into carbonate of lime and sulphide of hydrogen
(4th." reaction), in adding subsequently to the latter the other half of the bisulphite of
lime obtained in reaction.1 and in thus converting the latter into sulphur (capable
of producing sulphurous acid by combustion) and hyposulphite of lime and in subse-
quently separating from the latter by the aid of heat a precipitate or deposit consisting
of sulphur and sulphite of lime whence is produced by combustion sulphurous acid
and sulphite of lime, the latter being added to the sulphite of lime when treatment
No.13'is being carried out.
1000
CRUIKSHANK & FAIRWEATHER,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agents for the Applicants.