Decarbonation of Carbonate of Barium and Carbonate of Strontium.
Year: 1885

page_text: Decarbonation of Carbonate of Barium and Carbonate of
Strontium.
I, WILLIAM LLOYD WISE, of N° 46 Lincoln's Inn Fields, in the County of
Middlesex, Consulting Engineer and Patent Agent, do hereby declare the nature
of said invention for "IMPROVEMENTS IN APPARATUS AND MEANS OR METHOD FOR
THE DECARBONATION OF CARBONATE OF BARIUM AND CARBONATE OF STRONTIUM
"
(a communication to me from abroad by Raoul Radot of Paris, France, Engineer)
to be as follows:-
It is well known, that when a current of superheated steam is caused to pass
over carbonate of calcium, barium, or strontium heated to redness, the said
carbonates are decarbonated at a temperature comparatively lower than when
they are heated aloue or mixed with carbon. Hydrogen and inert gases produce
a similar result, varying in intensity with the speed of transit of the gas, with
the temperature of the steam, and with the temperature of the furnace.
In order to carry out the above mentioned process successfully it is essential that
the space, in which the decomposition takes place, and the steam or gas, which
facilitates the decomposition by its passage through the carbonate, should be highly
heated; nevertheless the process can be carried out economically by careful manage-
ment of the fuel. An arrangement of apparatus by means of which the above
named conditions may be commercially realized is constructed as follows:-
One or several retorts of refractory material containing the carbonate which is to
be decarbonated are arranged above a crucible made of a material that is as little
liable as possible to be attacked by the product formed, such as magnesia, silica,
alumina, anhydrous sulphate of barium or of strontium and the like.
The exterior of the retort and its crucible are highly heated by any direct source
of heat such as for instance by a heartb provided with a grate. The waste heat is
conveyed by two passages to a regenerator; one of these passages serving to heat
the walls of the upper part of the regenerator while the other heats the crucible.
rD013

page_text: As the flames issue from the upper part of the regenerator, they heat, by
transmission its lower chamber, the remaining available heat is employed in con-
verting into steam the water coutained in the boiler. The steam thus produced
is introduced into the above-named lower chamber of the regenerator becomes
heated and is then conducted into the channels which convey this superheated
steam to the crucible by as short a passage as possible, the said passage being
maintained at a high temperature by the several heated channels which sur-
round it.
The carbonate converted by the action of steam into a solid or liquid body is
discharged from the crucible through a door.
The action of the apparatus may be continuous or intermittent according as it is
desired.
In the case of the decarbonation of carbonate of barium, it is advantageous to fill
the lower portions of the retorts with a substance that is not attacked either by
the product under treatment or by the product formed, such substance of the kind
above mentioned being divided so as to form interstices through which the liquid
hydrate of barium formed can filter, carrying with it either mixed or in solution
portions of carbonate of barium which have not yet been decarbonated.
In this manner, the steam or gas comes into contact with the small drops of
hydrate of barium which filter through the interstices of the above-substance and
completes its action upon the portions of the carbonate carried down by the
hydrate.
:
The important points in the above described process are, that the temperature of
the superheated steam should be high enough not to cool the substance treated in
the retort and that the walls of the furnace surrounding the latter should be as
highly heated as possible, the decarbonation being most active when the tempe-
rature is highest. The retort containing the substance under treatment must be,
as above mentioned, as nearly unattackable as possible by the product treated or
formed and should also be as thin as practicable in order to allow the easy trans-
mission of heat into the product.
When the apparatus serving to superheat the steam by means of the waste
heat proceeding from the heating of the retort, is a generator, heating steam by
transmission, it should also be constructed of thin refractory material.
As regenerators can now be made with very thin refractory walls, it will be
easily understood that the steam is heated by the waste heat proceeding from the
fire serving to heat the retort, and will be at a temperature approaching that of the
retort whose walls must be necessarily thicker than that of the said regenerators
on account of its larger size.
The above superheating apparatus may also be formed of two contiguous
chambers, filled with refractory substances through which the waste heat and the
stram would be caused to pass in an intermittent manner, by means of reversing
valves of the class employed in Siemens' apparatus.
In all cases, the walls of the regenerator or recuperator and especially those of
the arched part of the same and of the channels collecting the superheated steam
should be subjected to the action of flames to compensate for losses of heat, super-
heated steam tending to lose a considerable portion of its acquired heat by the
slightest lowering of temperature.
The quantity of steam or gas that is required to be superheated being very small
as compared with the weight of the product under treatinent in the retort, there
will be an excess of waste heat which can be utilized for heating the air employed
in the combustion of the retort fire, previous to finally making use of such excess
of heat for vaporising the necessary water.
When earthy carbonates are reduced on a large scale, the retorts can be heated
by carbonic oxide gas which is burnt at the expense of the air heated in the
regenerators.
The gases escaping from the retort have a sufficiently high temperature to allow
of their being used for heating air or steam. When hydrogen is employed to act

page_text: upon the carbonates, the gas formed by the decarbonation, i.e. carbonic oxide, can
be used for heating the retort.
In the treatment of strontia, as the decarbonated strontia produced is not fusible
it is discharged from the retort in a solid form. It will be understood that if, in
this case, several vertical retorts of sufficient height be provided and heated
externally, steam being admitted at their lower part, such steam will become
superheated while passing through the pieces of strontia already decarbonated and
will then act upon the upper layers of substance in a sufficiently superheated state
to decarbonate the yet unreduced portions thereof. It is thus sufficient to cause
portions of the retort charge to fall intermittently, taking care to allow a quantity
of decarbonated strontia, sufficient to ensure the superheating of steam, to remain
constantly at the lower part of the said retort.
Instead of employing a vertical retort two horizontal or inclined retorts may be
used, and arranged in contiguity to one another in such a manner as to enable the
current of steam to operate inversely, by first being superheated in one of the
retorts in which the carbonate has been reduced and then acting upon the non-
decarbonated substance contained in the other retort; the said retorts communicate
together at their extremities by means of a connexion or tube arranged within the
heated surface.

page_text: Improvements in Apparatus and Means or Method for the
Decarbonation of Carbonate of Barium and Carbonate of
Strontium.
I, WILLIAM LLOYD WISE, of No 46 Lincoln's Inn Fields, in the County of
Middlesex, Consulting Engineer and Patent Agent, do hereby declare the nature
of this invention (a communication to me from abroad by Raoul Radot, of Paris,
France, Engineer,) and in what manner the same is to be performed to be parti-
cularly described and ascertained in and by the following statement:-
It is well known, that when a current of superheated steam is caused to pass
over carbonates of calcium, barium or strontium heated to redness, the said carbonates
are decarbonated at a temperature comparatively lower than when they are heated
alone or mixed with carbon.
Hydrogen and inert gases produce a similar result, varying in intensity with the
speed of transit of the gas, and with the temperature of the furnace.
In order to carry out the above mentioned process successfully it is essential that
the space, in which the decomposition takes place, and the steam or gas which
facilitates the decomposition by its passage through the carbonate, should be highly
heated. Nevertheless the process can be carried out economically by careful
management of the fuel.
Now this invention has for object to enable the above-named conditions to be
commercially realised and an arrangement of apparatus for this purpose is shown
in the accompanying drawings.
Figs. 1 and 2 are vertical sections, and Fig. 3 is a horizontal section.
A retort A (or there may be more than one) of refractory material containing
the carbonate which is to be decarbonated is arranged above a crucible B made of
a material that is as little liable as possible to be attacked by the product formed.
Suitable refractory materials for the crucible are magnesia, silica, alumina, anhydrous
. sulphate of barium or of strontium carbon or the like. The exterior of 'the retort
and its crucible are highly heated from any direct source of heat such as for
instance a hearth provided with a grate A¹. The waste beat is conveyed by two
circuits to a regenerator D, one of these circuits heats the walls of the upper part E
of the regenerator while the other heats the crucible B.
On leaving the regenerator the flames heat by transmission the lower chamber F
of the regenerator, their remaining available heat being employed in converting into
steam the water contained in a boiler G.
The steam thus produced in this boiler is introduced into the chamber F of the
regenerator, becomes heated in its passage therethrough and passes into the
channels E which convey this superheated steam to the crucible B by a passage (as
short as possible) maintained at a high temperature by the circulation of flame or
heated gases around it. The carbonate converted by the action of steam into a
solid or liquid body is discharged from the crucible B through the door H.
The action of the apparatus may be continuous or intermittent according as it is
desired,

page_text: In the case of the decarbonation of carbonate of barium, it is advantageous to
fill the bottom of the retorts with a substance that is not attacked either by the
product to be treated or that to be obtained, using for this purpose material such
as those indicated above and which must be divided so as to leave interstices
through which the liquid hydrate of barium formed can filter, carrying with it
either mixed or in solution, portions of carbonate of barium which have not yet
been decarbonated.
In this manner, the steam or gas comes into contact with the drops of hydrate of
barium which filter through the interstices of the said substance and acts upon the
portions of the carbonate carried down by the hydrate.
The important points to be observed are, that the temperature of the superheated
steam should be high enough not to cool the substance treated in the retort and
that the walls of the latter should be as highly heated as possible, the decar-
bonation being more active as the temperature is more elevated. The retort
containing the substance under. treatment must therefore be, as above mentioned,
of refractory earth as unattackable as possible and as thin as practicable in order
to allow the easy transmission of heat into the mass of the product.
When the apparatus serving to superheat the steam by means of the waste heat
proceeding from the heating of the retort, is a regenerator, heating steam by trans-
inission, it should also be constructed of thin refractory material.
As regenerators are now constructed with thin refractory walls, it will be under-
stood that with the flame or waste products from the heating of the retort, the
steam can be superheated to a temperature approaching that of the retort whose
walls must be necessarily thicker than that of the said regenerators on account of
its larger size.
The above steam superheating apparatus may also be formed of two contiguous
chambers, filled with refractory substances through which the waste heat and the
steam would be caused to pass in an intermittent manner, by means of reversing
valves as in Siemens' apparatus.
In all cases, the walls of the regenerator or recuperator and especially those of
the arched part of the same and of the collecting channels for superheated steam
must themselves be acted upon by the flames or heated gases (recevoir un
passage de flammes) to compensate for loss of heat, superheated steam tending to
lose a considerable portion of its acquired heat by the slightest lowering of
temperature.
The quantity of steam or gas that is required to be superheated being very
small as compared with the weight of the product to be heated in the retort,
there will be an excess of caloric remaining after heating of the retort which can
be utilized for heating the air to be employed for supporting combustion in the
retort fireplace and for generating the required steam.
When earthy carbonates are reduced on a large scale, the retorts can be
heated by carbonic oxide gas, which is burnt by means of the air heated in the
regenerators.
The gases escaping from the retort have a sufficiently high temperature to allow
of their heat being used for heating air or steam. When hydrogen is employed to
act upon the carbonates, the gas formed by the decarbonation being carbonic oxide
it can be used for heating the retort.
In the treatment of strontia, as the decarbonated strontia produced is not fusible,
it is discharged from the retort in a solid form. It will be understood that if, in
this case, there be one or several vertical retorts of sufficient height and heated
externally, steam being admitted at the lower part, such steam will become super-
heated while passing through the pieces of strontia already decarbonated and thus
it will act upon the upper layers of substance in a sufficiently superheated state to
decarbonate the yet unreduced portions thereof. It is thus sufficient to cause
portions of the retort charge to fall intermittently, taking care to allow a quantity
of decarbonated strontia, sufficient to ensure the superheating of steam, to remain
constantly at the lower part of the said retort.

page_text: Instead of employing a vertical retort two horizontal or inclined retorts may be
used, arranged in contiguity to one another in such a manner as to enable the
current of steam to be alternately changed, this current being superheated in one
of the retorts in which the carbonate has been reduced and then acting upon the
nou decarbonated substance contained in the other retort, the said retorts com-
municating with one another at their extremities by means of an ajutage arranged
within the heated enclosure (enceinte).
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me as aforesaid, I hereby declare that what is claimed is
1. Apparatus for the decarbonation of carbonate of barium and carbonate of
strontium. arranged and operating substantially as described.
2. Apparatus for the decarbonation of carbonate of barium and carbonate of
strontium, comprising a retort or retorts and fire-place, the arrangement being such
that the retort or retorts is or are intensely heated, and surplus heat is utilised in
superheating or producing the agents necessary for the process of decarbonation in
such a manner that an apparatus in working order may have a single fireplace, the
retort within which the re-action is effected being the part subjected to the greatest.
direct heat, substantially as described.
3. In apparatus of the kind referred to in the preceding claim, the admission at
a high temperature into the retort or retorts of the decomposing agent through an
undecomposable filtering mass, thereby enabling the decomposing agent to continue
its action upon the parts already decomposed carrying away with them in a liquid
state parts not decomposed, substantially as described.
4. The use of heat regenerators or recuperators in combination with apparatus
for the reduction of earthy carbonates of barium and strontium in a current of
super-heated steam, substantially as described.
5. For the treatment of strontium the use of retorts or groups of retorts wherein
steam is super-beated by the decarbonated product to act subsequently upon the
part undecomposed, substantially in the manner described above.
Dated this 11th day of November 1885