IMPROVEMENTS IN THE MANUFACTURE OF SALTS OF STRONTIA AND OXIDE OF STRONTIUM
Year: 1883

page_text: LETTERS · PATENT to William Augustus Rowell of 1 Jesmond Gardens
Newcastle-on-Tyne Chemical Manager for an Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF SALTS OF STRONTIA AND OXIDE OF STRONTIUM”
PROVISIONAL SPECIFICATION left by the said William Augustus Rowell
at the Office of the Commissioners of Patents on the 18th January 1883.
I, WILLIAM AUGUSTUS ROWELL of 1 Jesmond Gardens Newcastle-upon-Tyne
Chemical Manager "IMPROVEMENTS IN THE MANUFACTURE OF SALTS OF STRONTIA
AND OXIDE OF STRONTIUM
"3
This Invention has for its object improvements in the manufacture of salts of
strontia and oxide of strontium.
1st Sulphate of strontia or celestine and carbonate of soda are fused together by
beat in a reverberatory or other suitable furnace and thoroughly stirred into a
homogeneous mass whereby the two substances are decomposed and converted into
sulphate of soda and carbonato of strontia. The proportions used are the chemical
equivalents of the two substances with excess of carbonate of soda.
24 The mixture of sulphate of soda and carbonate of strontia thus formed is
treated with hot water which dissolves the sulphate of soda and leaves the carbonate
of strontia as a residue.
3rd This residue (which consists almost entirely of carbonate of strontia, with a
little undecomposed sulphate of strontia and impurities that may have been in the
materials used) is in the state of mud and is washed with warm water to free it
from sulphate of soda. It is then pumped into filter presses by which it is partly
deprived of its water and is produced as wet cakes of carbonate of strontia which
after being dried and heated to redness in a suitable furnace is ready for sale.
4th The wet carbonate of strontia is mixed with small coal and then dried and
strongly heated in a furnace or kiln by which it is reduced to the state of strontia

page_text: or oxide of strontium which may be either sold as such or be dissolved in water
crystallized and sold as hydrate of strontia.
5th The carbonate of strontia or oxide of strontium so produced may be used for
the manufacture of the chloride nitrate or any other salt of strontium.
6th The solution of sulphate of soda produced in the second operation described
above is evaporated and the resulting sulphate of soda is recovered and is either
sold as such or is used to make carbonate of soda by the well known Le blanc
process for the next operation. Or the solution of sulphate of soda produced is
allowed to crystallize and the crystals sold as Glauber's salts or calcined for making
pure sulphate of soda for sale.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Augustus Rowell in the Great Seal Patent Office on
the 17th July 1883.
WILLIAM AUGUSTUS ROWELL of 1 Jesmond Gardens Newcastle-on-Tyne Chemical
Manager "IMPROVEMENTS IN THE MANUFACTURE OF SALTS OF STRONTIA AND OXIDE
OF STRONTIUM”
This Invention has for its object improvements in the manufacture of salts of
strontia and oxide of strontium.
1 Sulphate of strontia or celestine and carbonate of soda are fused together by
heat in a reverberatory or other suitable furnace and thoroughly stirred into a
homogeneous mass whereby the two substances are decomposed and converted into
sulphate of soda and carbonate of strontia. The proportions used are the chemical
equivalents of the two substances with excess of carbonate of soda.
2nd The mixture of sulphate of soda and carbonate of strontia thus formed is
treated with hot water which dissolves the sulphate of soda and leaves the
carbonate of strontia as a residue.
3rd This residue (which consists almost entirely of carbonate of strontia with a
little undecomposed sulphate of strontia and impurities that may have been in the
materials used) is in the state of mud and is washed with water by boiling and
agitation to free it from sulphate of soda. It is then pumped into filter presses by
which it is partly deprived of its water and is produced as wet cakes of carbonate
of strontia which after being dried and heated to redness in a suitable furnace aro
ready for sale.
4th Or the wet carbonate of strontia is mixed with small coal and then dried or
preferably it is first dried and then mixed with tar pitch or sawdust in the propor-
tion of three parts of the former to one part of the latter. In either case the
mixture is then strongly heated in a furnace or kiln by which it is reduced to the
state of strontia or oxide of strontium which may be either sold as such or be
dissolved in water crystallized and sold as hydrate of strontia.
5th The carbonate of strontia or oxide of strontium so produced may be used for
the manufacture of the chloride nitrate or any other salt of strontium.
6th The solution of sulphate of soda produced in the second operation described
above is evaporated and the resulting sulphate of soda is recovered and is either
sold as such or is used to make carbonate of soda by the well known Le blanc
process for the next operation. Or the solution of sulphate of soda produced is
allowed to crystallize and the crystals sold as Glaubers salts or calcined for making
pure sulphate of soda for sale.
I find that the more finely the celestine is powderod the more complete the
decomposition it undergoes.
Carbonate of soda in any form may be used. The purer it is the purer the
resulting carbonate of strontia. In practice I use soda ash or sometimes what is
known in the Le blanc soda process as "black salt." This latter is of more variable
constitution than the former and is not always fit for use without the process
known as "carbonating" which converts it into soda ash, when it can be used
considerable economy results.
I find that it is better to have an iron.or cast metal bed to the furnace as other-
wise when the sodic carbonate fuses it acts on the bricks, particles of which, besides
silica and alumina are thus brought into the carbonate of strontia.
It is possible to decompose with ono equivalent of carbonate of soda, but to do
the work well and rapidly excess of carbonate of soda is desirable.

page_text: It is sometimes advisable to add a little caustic soda to the carbonate of soda
used or to use soda ash containing caustic soda.
When this is done certain impurities in the celestine, themselves insoluble, form
soluble compounds with the soda and are extracted along with the sulphate of soda
by solution in water. Such soluble compounds can in some cases be decomposed
in solution so as to precipitate the impurities in question, well known methods
only being used.
The mixture of carbonate of strontia and sulphate of soda is, when drawn from
the furnace and cooled a very hard and slag like mass and to dissolve it quickly
and economically it should be crushed fine. Then it is thoroughly boiled with
water and the sulphate of soda and other soluble constituents are extracted.
The solution of sulphate of soda will contain carbonate of soda if any excess of
carbonate has been used or if the operation has not been thoroughly carried out,
from deficient grinding of celestine or mixing in the furnace.
This however is of no importance for using the sulphate of soda for the next
operation in the Le blanc process but it can be converted into sulphate by known
methods or by boiling with a little sulphate of strontia finely powdered as described
in the specification of my Patent N° 292.
The aluminate and silicate of soda existing in the soda ash or which may have
been formed in the process can be precipitated by known methods from the
sulphate of soda solution and the sulphate of soda liquors generally can be purified
by any method which is or has been used to purify "tank liquors" in the Leblanc
process.
I find the following process very suitable.―
I add to the solution of sulphate of soda a solution of nitre cake i,e, bisul-
phate of soda taking care to add such a quantity as to leave the solution still
alkaline.
The free acid of the nitro cake neutralizes the aluminate, silicate and hydrate
of soda forming sulphate of soda, precipitating the great bulk of the alumina and
silica. The sulphate of soda in the nitre cake is obtained as such along with the
rest.
I am aware of the Patent granted to David Urquhart N° 282 in the present
year. The specification of the said process describes the process of roasting a
mixture of sulphate of soda with carbonaceous matter and carbonate of soda in the
form of black ash.
To this process, which results in the formation of sulphide of sodium together
with other products, I make no claim But what I claim is the decomposition by
fusion of a mixture of sulphate of strontia and carbonate of soda into carbonate of
strontin and sulphate of soda, substantially as described.
I also claim the process for the manufacture of carbonate of strontia, consisting
in fusing the sulphate of strontia with carbonate of soda, washing the product
with water, and consolidating the residue into cakes by means of a filter press
substantially as described.
In witness whereof I the said William Augustus Rowell have hereunto set my
hand and seal this thirteenth day of July in the year of our Lord One thousand
eight hundred and eighty three.