IMPROVEMENTS IN DECARBONATING CARBONATE OF STRONTIA AND IN APPARATUS THEREFOR
Year: 1884

page_text: I, JOHN IMRAY of No 28 Southampton Buildings, Chancery Lane in the County
of Middlesex Consulting Engineer and Patent Agent do hereby declare the
nature of the said invention for "IMPROVEMENTS IN DECARBONATING CARBONATE
OF STRONTIA AND IN APPARATUS THEREFOR to be as follows:―
In a Provisional Specification filed by me on the 23rd January 1884 N° 1998,
being a communication to me from my correspondent, were described apparatus
by means of which the transformation of carbonate of strontia into anhydrous
strontia was effected under the influence of superheated steam. The carbonate
of strontia was contained in retorts or chambers heated by external fire heat,
and when the requisite temperature was attained superheated steam was introduced
to effect the dehydration of the strontia.
This arrangement has the disadvantage among others, of requiring a number of
retorts which are subject to fracture and deterioration.
According to the present invention this inconvenience is obviated by first heating
the carbonate of strontia to a red heat and then applying the necessary heat directly
thereto for its conversion into anhydrous strontia by means of the superheated
steam itself, which is for this purpose heated to a very high degree before it is
brought in contact with the previously heated carbonate of strontia.
The construction of apparatus employed for this purpose is as follows: A vertical
chamber or kiln has at its upper end a number of retort-like extensions closed at
top by covers and opening into the kiln at bottom and surrounded by a chamber
containing a furnace by which they can be heated to a red heat. Near the bottom
of the kiln are lateral chambers heated by a furnace and containing horizontal
retorts charged with pieces of refractory material, which retorts are closed at the
outer end by a cover and have their perforated inner ends communicating with
the kiln. Steam being introduced into the retorts by a pipe, it becomes heated
to a very high degree before passing into the kiln. The furnaces containing these
retorts are connected by passages with the interior of the kiln, so that when required
the heat may be admitted directly from the former into the latter; they have also

page_text: flues leading firstly underneath evaporating pans for evaporating the mother liquor
resulting from the precipitation of the sucrate, and then passing to a chimney.
The action of the apparatus is as follows: Assuming the kiln to be charged with
carbonate of strontia, fresh carbonate such as results from the decomposition of the
sucrate by preference moulded into tubular form, is introduced from time to time
into the vertical retorts at top, and in descending through these it becomes heated
to a red heat before entering the kiln. Here it is subjected to the direct heat of
the highly superheated steam entering through the retorts at bottom, so that as it
gradually descends in the kiln it is completely converted into anhydrous strontia,
and is removed from time to time through doors at the bottom of the kiln.
On first starting the kiln, it is heated to a considerable degree before being
charged by admitting the direct heat from the furnaces of the steam superheating
apparatus, after which it is charged with natural carbonate of strontia, and the
direct communication of the furnaces having been closed, superbeated steam is
admitted. As the decarbonated natural strontia is gradually removed at bottom,
the moulded tubes of carbonate of strontia produced from the decomposition of
sucrate are gradually charged into the retorts at top, so that the kiln eventually
becomes completely charged with the moulded carbonate. When treating the
natural carbonate the conversion into anhydrous strontia will not always be
perfect, in which case the product may be treated with boiling water so as to
extract the soluble strontia, and the remaining unconverted carbonate can be
mixed with the other carbonate and be again subjected to the action of the steam.
The requisite supply of steam may advantageously be derived from the waste
steam of the ordinary sugar refining apparatus, which steam is usually employed
for evaporating the juice in the triple action apparatus. This application is not
needed when the process for the production of insoluble sucrate of strontia is
employed, which when decomposed by means of carbonic acid yields syrups of a
higher density than that obtained by the evaporation by triple action, and conse-
quently the waste steam can be employed with advantage for furnishing the super-
heated steam for the above described process, thus saying the cost of fuel necessary
for raising steam specially for this purpose.

page_text: I, JOHN IMRAY of N° 28 Southampton Buildings Chancery Lane in the county
of Middlesex, Consulting Engineer and Patent Agent, do hereby declare the
nature of my invention for "IMPROVEMENTS IN DECARBONATING CARBONATE OF
STRONTIA AND IN APPARATUS THEREFOR" and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
In a Provisional Specification filed by me on the 23rd January 1884 N° 1998;
being a communication to me from my correspondent were described apparatus
by means of which the transformation of carbonate of strontia into anhydrous
strontia was effected under the influence of superheated steam. The carbonate
of strontia was contained in retorts or chambers heated by external fire heat,
and when the requisite temperature was attained superheated steam was introduced
to effect the dehydration of the strontia.
This arrangement has the disadvantage, among others, of requiring a number of
retorts which are subject to fracture and deterioration.
:
According to the present invention this inconvenience is obviated by first heating
the carbonate of strontia to a red heat and then applying the necessary heat directly
thereto for its conversion into anhydrous strontia by means of the superheated
steam itself, which is for this purpose heated to a very high degree before it is
brought in contact with the previously heated carbonate of strontia.
Apparatus applicable for this purpose is shewn in the accompanying drawings of
a strontia decarbonating kiln. Figs. 1 and 2 are vertical sections on planes at
right angles to each other. Fig. 3 is a plan of the top of the kiln, fig. 4 is a
sectional plan on X X of fig. 2 and fig. 5 is a longitudinal section on Z Z of fig. 4.
At the top of the kilo are a number of retort-like extensions A closed at the top
by removeable covers and opening at the bottom into the body of the kiln. These
retorts are heated to red heat by a fire B. At the bottom of the kiln on each side
are arranged in a furnace chamber a number of retorts C, each of which is closed
at the outer end by a removeable cover and has its inner end opening by numerous
perforations into the body of the kiln. These retorts being charged with fragments
of fire brick or other refractory material are highly heated and theu steam being
passed through them becomes greatly superheated as it enters the kiln. The
products of combustion of the retort furnaces may pass away by flues D or may
be wholly or partly directed through openings E into the body of the kiln.
On starting the kiln, it is in the first place highly heated by the furnaces of the
retorts C, and the retorts A are also heated, by the fire B. The body of the kiln
is then filled up with natural carbonate of strontia and the retorts A are charged
with the pieces of carbonate of strontia moulded in tubular form which rest on the
natural carbonate below. When the charge is well heated, steam is passed through
the retorts C, and the superheated steam acting on the heated material in the kiln
decarbonates it.

page_text: -
The lumps of decarbonated material are from time to time raked out at the
bottom openings F, and as the charge descends in the kiln fresh moulded tubes of
carbonate are introduced into the retorts A to become heated and to descend and
to be decarbonated and raked out in their turn. Lateral openings G are provided
at various heights to stir, when necessary, the contents of the kiln.
When treating the natural carbonate, the conversion into anhydrous strontia
will not always be perfect, in which case the products may be treated with boiling
water so as to extract the soluble strontia, and the remaining unconverted carbonate
can be mixed with the other carbonate and be again subjected to the action of the
steam.
The requisite supply of steam may advantageously be derived from the waste
steam of the ordinary sugar refining apparatus, which steam is usually employed
for evaporating the juice in the triple action-apparatus. This application is not
needed when the process for the production of insoluble sucrate of strontia is
employed, which, when decomposed by means of carbonic acid yields syrups of
a higher density than that obtained by the evaporation by triple action, and
consequently the waste steam can be employed with advantage for furnishing the
superheated steam for the above described process, thus saving the cost of fuel
necessary for raising steam specially for this purpose.
The flues D may, on their way to a chimney be led under evaporating pans, so
that the heat of the products of combustion may be utilised for evaporating the
mother liquor resulting from precipitation of the sucrate of strontia.
Having now particularly described and ascertained the nature of my invention
and in what manner the same is to be performed, I declare that what I claim is
1, The herein. described method of decarbonating carbonate of strontia by
feeding moulded pieces thereof into heated vertical retorts, whence they descend
heated into a kiln and are subjected therein to the action of superheated steam,
the material thus decarbonated being removed at the bottom of the kiln.
2, The construction of kiln for decarbonating carbonate of strontia, substantially
as described and illustrated by the drawings.