A Process and Apparatus for Melting and Moulding Salt into Compact Blocks.
Year: 1899

page_text: A Process and Apparatus for Melting and Moulding Salt into
Compact Blocks.
I, FREDERICK WILLIAM GOLBY, of 36, Chancery Lane, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention, as
communicated to me by the Firm of Matray Frères & Co., of 31, Boulevard
Henri IV., Paris, France, to be as follows:-
The object of this invention is a process and apparatus by which salt is heated
to the point of fusion and moulded into blocks, whereby salt blocks are obtained
ready for use,
in a simple, easy and economical manner.
The process consists firstly in melting the salt by means of gas blow pipes or
voltaic arcs in suitable furnaces protected against the falling of the salt in their
vertical plane by suitable cross pieces, the employment of either of these heating
arrangements being intended to render the salt liquid, or only paste-like, in
order to enable it to be moulded into blocks of any dimensions whatever.
The closing of the upper part of the furnace which is open, is effected by the
salt itself.
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Secondly, the blocks thus obtained by melting, and casting, sometimes show
fissures. To obviate this, a furnace in the form of a circular tunnel is used in
which a plate which is also circular, rotates continuously. On this plate the
previously moulded blocks of salt are placed. In passing under the tunnel, the
blocks are exposed, independently of the heat circulating around, to the action
of the gas blow pipes which "radiate" in the tunnel, and the effect of which is
to cause the salt to run over the whole surface of the blocks, making a kind
of covering which is very hard and very smooth, and stopping up the fissures.
Moulding apparatus specially arranged for facilitating the removal of the
blocks from the moulds is employed, said apparatus being arranged below the
outlets or tap-holes of the furnaces, where the moulds are successively brought to
be filled. One arrangement of said apparatus is nothing more than a kind of
bucket-chain, the buckets being of a suitable form and acting as moulds.
This chain is arranged on two wheels, one being furnished, with
a handle for working the chain of buckets and, bringing forward a fresh mould
under the outlets and, at the same time throwing a block into any kind of
receptacle. A second arrangement is formed of a single bucket-wheel acting like
the chain described above. This wheel, which is composed of two principal parts,
between which are arranged the moulds, has on one side a series of holes in
number equal to that of the moulds, in which holes a spring bolt supported in
the frame, engages successively.

page_text: COMPLETE SPECIFICATION.
A Process and Apparatus for Melting and Moulding Salt into
Compact Blocks.
I, FREDERICK WILLIAM GOLBY, of 36, Chancery Lane, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be described as communicated to me by the Firm of
Matray Freres & Co., of 31 Boulevard Henri IV., Paris, France, to be particu-
larly described and ascertained in and by the following statement:-
The furnaces hitherto employed for melting salt have many drawbacks, as
regards the heavy cost of such apparatus, the loss of time which they involve,
owing to the defective heating obtained therefrom for a substance like salt,
and the losses arising from volatilisation.
It is easy in fact to understand that with such furnaces, which have a certain
resemblance to glass-furnaces, the difficulties and the time lost during the operation
make the cost price considerable.
1. It is first necessary to heat the furnace considerably for several days before
it is in a condition to commence melting the salt.
2. When a furnace of this kind is once set going, it is necessary to work con-
stantly day and night, and the slightest incident causing a cessation or slackening
of the heat, interferes with manufacture often for many hours as the salt
melted in the furnace solidifies and when the heating is resumed, it is necessary
to wait some time before the salt becomes liquid.
Moreover, the least repair or even a simple cleaning operation, involves a
prolonged stoppage; as it is necessary each time to wait several days for the
furnace to cool and after the repairs have been effected to submit to further
delay before resuming the work.
3. In consequence of the readiness with which the salt is volatilised, it cannot
be superheated, and therefore, however the burners may be arranged, it is
well-nigh impossible to avoid having places in the bottom of the furnace where
the temperature is too high and where a rapid volatilisation takes place whilst on
the contrary other places are not hot enough for melting the material.
These disadvantages, of which my correspondents only briefly mention the
principal, are thus very serious, particularly when connected with the manufacture
of an article which, for commercial purposes, must be cheap.
The present process, which is intended to effect the heating of salt to a point
where it is reduced to a liquid or to a paste-like condition in order to mould
it into blocks without the necessity of employing such furnaces, consequently
effects an important improvement by enabling blocks of salt to be manufactured
by means at once simple, easy and inexpensive.
The problem which my correspondents have desired to solve consists in heating
the salt intensely by means of such arrangements that the manufacture is, so
to say, started instantaneously, so that accidental stoppages need no longer be
feared but may be made as desired, for example, or by working only during the
day, if the production does not necessitate working by night, and actually stopping
the manufacture during the hours of rest.
This result is obtained by the means described hereinafter.
1. Heating with a blow-pipe.
This consists theoretically in directing a gas blow-pipe on to a certain quantity
of salt formed into a heap. The temperature of the blow-pipe flame is sufficient
to effect the melting of the salt which is received in a mould. In practice, in
order to avoid the loss of heat and easily collect the melted salt, it is necessary
to have recourse to certain arrangements, two of which are illustrated by way of
example in the accompanying drawings.
Fig. 1 is a vertical section taken on the line G H of Fig. 2; and Fig. 2 is
a plan of the apparatus;

page_text: Fig. 8 is a modification of Fig. 3;
Fig. 9 is a modification of Fig. 6;
Fig. 10 is a plan of a modification of the apparatus illustrated in the preceding
figures;
Fig. 11 is a section along the line R S of Fig. 10;
Figs. 12 and 13 are modifications of the apparatus shown in Figs. 10 and 11;
Figs. 14, 15 and 16 are views in side and end elevation of two forms of apparatus
for removing the blocks of salt from the moulds.
Referring to Figs. 1, 2 and 3, this arrangement consists in a melting pot A
formed of an outer metal casing lined with refractory material. The gas is
introduced at C through the blow-pipe D and the burned gas passes out at C'.
The cross piece B protects the passage of the gas and divides the salt which runs
on to the shelves or brackets E. The melted salt falls into the bottom of the
melting pot A and runs away through the orifice F which is kept at the necessary
temperature by another blow pipe D¹. In this arrangement it will be seen that
the cover of the melting-pot is formed by the salt itself. The highly elevated
temperature of the blow-pipe is thus developed in a closed space which has no
communication with the outer air except by the orifice C, which serves as an
outlet for the burned gas. In this arrangement, as well as in the following ones,
indicates spy-holes for observing the work.
Referring to Figs. 4, 5, 6 and 7. This arrangement is substantially the same
as the preceding one as regards mode of working.
It consists in a sort of passage or chamber made of refractory brick or stone
work through which blow pipes I run at necessary intervals. The blow-pipes
may be in any number according to the length of the chamber. The refractory
slabs G protect the gas passages, and the slabs G¹ prevent the salt from running
down towards the orifice F so that throughout the length of the refractory brick
work chamber there is open communication between the orifices in order that
the melted salt may be divided equally over all, even if the melting be proceeding
more actively at one or several points.
The salt is placed on the slabs G where it begins to be heated and runs down
into the interior of the refractory brick work chamber through the spaces left
free between the slabs G, in proportion as the melting proceeds. As in the
apparatus shown in Figs. 1, and 3, the salt shuts off the communication with
the external air and the chamber only communicates with it by the orifices C¹,
which serve as outlets for the burned gases.
2. Heating by means of a voltaic arc.
In the arrangements of apparatus described above, the heating by gas may be
replaced by heat generated by a voltaic arc, as shown in Figs. 8 and 9. In this
case, all that is necessary is to introduce the electrodes through the orifices
which serve as inlets and outlets for the gas. In this arrangement, the salt is
melted in an absolutely closed vessel, as the upper part of the apparatus is
obstructed by the salt to be melted, and the orifice is closed by the passage
of the melted salt, the electrodes fitting tightly into the apparatus, so that there
cannot be any loss by volatilisation.
3. Heating by gas of the previously moulded blocks, illustrated in Figs. 10
and 11.
Under this arrangement, the salt is first moulded into blocks by being com-
pressed into the necessary form. One arrangement for effecting this operation
described as an example, is that of placing the blocks on a carrying plate T
which moves in a small circular tunnel A heated by gas. The heat must be
regulated so as to correspond to dark red heat at the entrance a² of the tunnel

page_text: so that it penetrates the block without at once producing fusion. It must be
increased progressively to correspond to the fusing point of the salt towards the
exit a³ of the tunnel in such a manner that, at this point, a slight superficial
casting is produced forming the glaze of the blocks.
In these figures U represents the refractory plate covering the platform, V the
gas-circulating pipes, the burners, and X the chimney for carrying off the burnt
gases.
At the entrance and at the exit there is of course a sliding door which is moved
to allow the blocks to pass in and out each time the plate is moved forward.
4. Heating by electric current of the blocks previously moulded, illustrated
in Figs. 12 and 13.
Under this arrangement use is made of the property possessed by the electric
current of producing a considerable heating effect when it is carried through a
body that offers great resistance.
The following is one arrangement described by way of example;
The salt in the form of powder compressed into the desired shape (Fig. 12) is
placed on an electrical conducting plate a serving as an electrode and resting
on insulating supports b. A piece of metal c in any shape forming the other
electrode is placed on the block of salt s. In this way, a current of sufficient
intensity is introduced for heating the salt to a condition of paste-like fusion
producing, through the welding of the crystals together, the formation of a
complete block. The current may circulate in either direction.
With a view to economise the current, this method may be combined with
heating by gas, by introducing the electric current into the blooks already heated
to a certain temperature, whether the salt has been heated before the moulding
or after, or by introducing the current into the blocks obtained by liquid fusion
in order to restore them to the paste-like state for the purpose of removing any
cracks which may be in them.
Fig. 13 represents by way of example and arrangement for enabling the opera-
tion to be effected continuously in regard to the blocks heated after previous
moulding. The circular plate T described above (Figs. 10 and 11) has at
intervals corresponding to the blocks of salt a metallic piece d inserted in the
refractory platform or floor, which comes into contact with the underneath part
of each blocks and serves as an electrode. At the outlet of the tunnel, the
electrode is lowered into contact with the block of salt, the spring contact e
is likewise connected to d and current introduced until the temperature reaches
the point at which the crystals are welded together.
For the blocks obtained by liquid fusion or the material of which has been
heated before compression, all that is necessary is to remove them from the
moulds on to the insulated plate shown in Fig. 12.
In addition to the means above described for fusion and moulding salt, other
means have been devised relating to the other parts of the manufacture and which
are useful for improving the product and reducing the cost price.
Cooling of the blocks of salt.
In order to rapidly cool the blocks which are formed in the moulds by the
"cast" liquids, a tube is carried towards the interior of these moulds which blows
air at a very low temperature at the same time as the liquid fills the mould.
In this way very close crystallisation is obtained and consequently great com-
pactness and density in the blocks of salt. The quantity of air introduced and
the temperature of the same are proportioned to the rapidity of the casting and
regulated in such a manner that the salt remains sufficiently fluid to assume the
form of the mould.
Bleaching of the melted salt.
When the salt contains organic matters, their incomplete combustion causes
them to be rather strongly coloured. Hitherto, for the purpose of bleaching the
salt, it has been usual to add thereto certain chemical salts, the decomposition of

page_text: In order to economise these rather expensive substances, a tube is introduced
into the interior of the melting pot (Figs. 1, 2 and 3) and the chamber (Figs. 4, 5,
6 and 7) which tube opens near the casting holes and through which tube super-
heated air is injected into the melted salt. The oxidation and combustion of the
organic matters mixed with the melted salt is thus effected without the addition
of any substance whatever.
Automatic removal of the blocks of salt from the moulds.
When the blocks have been obtained by liquid casting in the moulds, the
expense of removing the blocks from the moulds by hand considerably increases
the cost price. For the purpose of obviating these expenses mechanism is pro-
vided for conducting the moulds under the casting orifices and then turning them
over so that the blocks slide to the ground automatically, or better still into a
carriage which conveys them to the warehouse. Two of these arrangements are
illustrated by way of example in Figs. 14, 15 and 16.
In the form shown in Fig. 14 the apparatus consists of an endless carrier the
moulds n of which successively discharge their blocks of salt s.
In the form shown in Figs. 15 and 16 the apparatus consists of two sheets or
plates of round sheet iron m secured on an axis. The moulds n are placed between
the two plates and held by tightening nuts. If it be supposed that the apparatus
turns from left to right, the moulds comprised in the right hand portion between
the casting of the salt and the point at which the blocks are removed from the
moulds, are full. The apparatus thus rotates of itself when the pin is drawn
back. This pin presses by means of a spiral spring g on one of the plates m
so that when it has been drawn back and the apparatus is moved to the extent
of the width of a mould the pin left to itself fits automatically into the following
hole o and thus stops the apparatus.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
--
In the process and apparatus herein described for melting and moulding salt:-
(1) The use of a gas blow-pipe the heat of which is concentrated on the salt
substantially in the manner and by the means described.
(2) Effecting the fusion of the salt by utilising the heat produced by a voltaic
arc.
(3) Heating the blocks of salt previously moulded by exposing them to a
temperature which penetrates the blocks and produced a welding together of the
crystals in bringing them progressively to a paste-like condition.
(4) The manufacture of the blocks of salt by introducing into the blocks
previously moulded an electric current of sufficient intensity.
(5) The manufacture of the blocks of salt by the introduction of an electric
current into the blocks previously heated.
(6) The introduction of the electric current into the blocks moulded by liquid
fusion, with the object of getting rid of cracks.
(7) The cooling of the salt at the moment of the casting by the injection of
cold air into the moulds.
(8) The bleaching of the salt by the injection of superheated air into the
melted salt.
(9) The automatic removal from the moulds of the blocks of salt, two arrange-
ments of which are shown by way of example in the accompanying drawings.
Dated this 17th day of April 1900.
F. W. GOLBY,
Patent Agent, 36, Chancery Lane, London, W.C.