Improvements in the Manufacture of Carbonates of Strontium and Barium.
Year: 1891

page_text: Date of Application, 24th Dec., 1891
Complete Specification Left. 24th Aug., 1892-Accepted. 24th Sept. 1892
VISIONAL SPECIFICATION.
Improvements in the Manufacture of Carbonates of Strontium and
Barium.
We JOHN BROCK of Wellfields, Widnes in the County of Lancaster Alkali
Manufacturer and JOHN THEODORE MARSH of the British Alkali Works
Widnes aforesaid Chemist do hereby declare the nature of this invention to be as
follows:-
The object of our invention is to effect the preparation on a manufacturing scale
of carbonate of strontium or carbonate of barium free from sulphur.
In the manufacture of these carbonates as at present practised a solution of the
corresponding sulphides or hydrosulphides is treated with carbonic acid gas,
obtained from lime kilns, whereby the strontium or barium (as the case may be) is
precipitated as carbonate, sulphuretted hydrogen being liberated. Owing to the
presence of polysulphides in the solution, and of traces of oxygen in the carbonic
acid gas a small amount of free sulphur is always precipitated with the carbonate
of strontium or barium and by combining with the carbonate during the subsequent
operation of drying renders the product unfit for use.
To remove this sulphur we boil the precipitated carbonate suspended in water
with the corresponding hydrate; that is to say we boil carbonate of strontia with
strontium hydrate and carbonate of baryta with barium hydrate.
The sulphur dissolves in the hydrate, and the solution may be used in the former
stage of the process that is in the treatment with carbonic acid, whereby the
strontium or barium in solution is recovered without loss.
In carrying our invention into practice we may proceed as follows.
contents of the carbonator, when all the strontium or barium sulphide has been
We run the
precipitated as carbonate, into a vessel fitted with an agitator, where it is heated
with steam, or otherwise, to the boiling point. We then add a quantity of crystals
of strontium hydrate or barium hydrate (as the case may be) sufficient to combine
with all the sulphur contained in the precipitated carbonate.
the liquid until the whole of the sulphur has dissolved and combined with the
We continue to boil
hydrate.
The precipitate (carbonate of strontia or baryta) is then separated from the
solution by means of a filter press, or in any other way, washed with hot water and
then dried.
Dated this al 1
C D
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Carbonates of Strontium and
Barium.
We. JOHN BROCK of Wellfields Widnes in the County of Lancaster Alkali
Manufacturer and JOHN THEODORE MARSH of the British Alkali Works
Widnes aforesaid Chemist, do hereby declare the nature of our invention, and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:—
The object of our invention is to effect the preparation, on a manufacturing scale
of carbonate of strontium or carbonate of barium free from sulphur.
In the manufacture of these carbonates as at present practised, a solution of the
Price 8d7

page_text: corresponding sulphides, or hydrosulphides, is treated with carbonic acid gas,
obtained from lime-kilns, whereby the strontium, or barium, (as the case may be),
is precipitated as carbonate, sulphuretted hydrogen being liberated. Owing to the
presence of polysulphides in the solution, and of traces of oxygen in the carbonic
acid gas, a small amount of free sulphur is always precipitated with the carbonate
of strontium, or barium, and, by combining with the said carbonate during the
subsequent operation of drying, renders the product unfit for use.
To remove this sulphur we boil the precipitated carbonate, suspended in water,
with the corresponding hydrate; that is to say, we boil carbonate of strontium
with strontium hydrate, and we boil carbon.ute of barium with barium hydrate.
The sulphur dissolves in the hydrate and the resulting solution may be used in a
former stage of the process for dissolving a fresh portion of sulphide, and, after
crystallising out the hydrate, treating the mother liquor with carbonic acid gas as
is well understood, whereby the strontium, or barium, in solution is recovered
without loss.
In carrying our invention into practice we may proceed as follows:-We run
the contents of the carbonator, (when all the strontium, or barium, has been
precipitated as carbonate), into a vessel, provided with an agitator, wherein the
said contents are heated to the boiling point in any convenient way for instance
by means of steam. We then add crystals of strontium hydrate, or barium hydrate,
(according to whether carbonate of strontium, or carbonate of barium, is being
manufactured), in quantity sufficient to combine with all the sulphur contained in
the precipitated carbonate.
In the case of strontium carbonate we find that usually 2 cwt., or thereabouts,
of crystallized strontium hydrate, (S,H2O2 + 8 H₂O), will readily remove all the
sulphur from such a quantity of precipitated strontium carbonate as would
correspond to one ton when dry.
In the case of barium carbonate we find that usually 2 cwt., or thereabouts, of
crystallised barium hydrate, (BH₂O₂ + 8 H₂O), will readily remove all the sulphur
from such quantity of precipitated barium carbonate as would correspond to one
ton when dried. We continue the boiling until the whole of the sulphur has
dissolved and combined with the hydrate. Usually this result is achieved by
boiling for about half an hour.
The precipitate (carbonate of strontium, or barium,) is then separated from the
solution by means of a filter-press, or in any other way, washed with hot water, and
then dried.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
In the manufacture of carbonate of strontium, or carbonate of barium, boiling
the carbonates with the corresponding hydrates, substantially as described, for the
purpose of removing free sulphur from such carbonates.
Dated the 24th day of August 1892
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.