Improved Process and Apparatus for Condensing Arsenious Acid, Metallic Fumes, and the like.
Year: 1899

page_text: Date of Application; 7th Apr., 1899-Accepted, 11th Nov., 1899
[Communicated from abroad by ALCIDE FROMENT, of Tavagnasco, in the Province
of Turin, and Kingdom of Italy, Engineer.]
Improved Process and Apparatus for Condensing Arsenious Acid,
Metallic Fumes, and the like.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster, and
Lower Temple Street, Birmingham, in the County of Warwick, Civil Engineer,
do hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
It is well known that arsenious acid has up till now only been collected in very
long flues or chambers arranged in series. Certain condensing flues have some-
times a length of three to four hundred meters, and still the whole of the arsenical
vapours or fumes is not always condensed.
Factories cannot always procure sufficient space to establish these long series
of condensing flues from which, moreover, the products are not collected without
difficulty and much labour. On the other hand, the construction of these cham-
bers or flues is very costly and involves constant repairs.
The object then of the present invention is a condenser for arsenious acid and
for fumes of lead zinc and the like, the installation of which is inexpensive, which
requires little space and which works automatically and conducts the products
into bags or other receivers.
For the better comprehension of my invention, I will describe it with reference
to the accompanying drawings, in which:-
Figure 1 shows a longitudinal section of the apparatus with its accessories and
connections.
Figure 2 shows a detailed elevation of the closing arrangement of the cylinder.
The apparatus is composed of
1st. A cylinder of thick sheet iron d with a double cover, between which is a
space more or less large according to the development given to the apparatus, the
medium size of which space is from 50 to 70 millimeters.
This cylinder is covered internally with several coats of varnish not affected
by sulphurous, sulphuric, arsenious and the like acids, or preferably with a covering
of sheet lead from 3 to 4 millimeters thick.
Secondly. A screw with double walls d' exactly filling the cylinder. There is
a space of from 5 to 8 millimeters between the walls of this hollow spiral screw,
which turns round a hollow axis the interior of which communicates with
the interior of the spiral.
This axial tube can be closed at will by means of cocks rr placed at the begin-
ning and the end of the spiral.

page_text: At the end of this axis is a small light hydraulic paddle wheel the diameter
of which should correspond to the speed it is desired to give to the spiral but it
is preferable to give it a small diameter for instance of from 80 centimeters to
one meter, consequently a considerable speed unless checked by the regulating
water cock o.
It is understood that the two ends of the cylinder are closed in such a manner
as to prevent the gases circulating therein from escaping. The cylinder is, how-
ever, open at e for the entry of the sulphurous and arsenious acid gases coming
from the fume chambers a, and at for the exit of the sulphurous gases, and
at to allow the condensed products to fall into the reservoir m. It moreover
communicates with the tubes h and i by a cock y y'.
The interior of the double casing communicates with a water pipe g provided
with a cock as well as with the tubes and each closed by cocks o and o
whilst the axial tube of the spiral screw communicates with a tube f having a
cock which conducts the water into the hollow spiral, that is, into the above
mentioned double walled screw d', the water from the hollow spiral being dis-
charged into the interior of the paddle wheel through holes pierced on the
periphery of the hollow axis d". A cylinder of sheet iron covered with lead and
provided with an observation hole 7 is fitted into the opening k. At the bottom
of.this cylinder is a closing device opening into the reservoir m which is of sheet
iron covered internally with lead. On the right hand inside the reservoir is a
filter charged with sand and powdered charcoal. The reservoir is also pro-
vided with a discharge door n.
A steam heating apparatus s at high pressure supplied by the pipe s¹, is covered
with some material which is a non-conductor of heat, and is placed above the
condenser, it being necessary to warm the gases before they penetrate into the
Glover tower by means of the passage and the conducting pipe. This
heating apparatus is supplied by a steam generator connected with it by means
of the pipe s
Above the heating apparatus are placed a pressure gauges and a safety
valves. The tube can have an oval form indicated by the dotted lines p¹
which seems to be more favourable for a better utilization of the heat. A ther-
mometer is placed in the heating apparatus but it would be well to add another
in the tubes illi above the heating apparatus.
is a discharge for the steam, whilst serves for the running off of the
water coming from the condensed steam. When it is a question of condensing
lead and zinc fumes and metallic fumes in general, it is as well to place a conical
flannel filter in r in order to collect every trace of the products which may have
escaped during condensation. 11 is an apparatus for carrying away the products
of condensation. the reservoir for collecting the weak acids. is the first
bottom of the condensing cylinder and the running off pipe that is, the discharge
channel for the water of the wheel. b is a flat block placed above the fume cham-
bers a and c c indicate the beams on which the condenser rests.
In Figure 2 representing the closing device of the cylinder, f indicates the tube
conducting the cold water, 2 the lubricator, 1 the washers of indiarubber, 3 the
indiarubber washers turning with the axial tube 5 an indiarubber washer
fixed at the bottom of the condenser, 4 the bottom of the condenser, 6 an india-
rubber washer fixed on the axial tube d" and turning with it, 8 the iron shoulder
on the axial tube on which the flange springs rest which supports the plate G
against the bottom 4, and 7 a lubricator.
Operation of the apparatus:-
The sulphurous and arsenious gases or the metallic fumes are conducted into
the fume chambers a by a large pipe of sheet iron a¹ covered with some protec-
tive varnish which discharges into the arrangement of filters which fill the entire
space of the chamber all from 50 centimeters above the floor.
Each filter is composed of small fragments of poplar wood charcoal, resting

page_text: on gratings of lead wire. These gratings are placed above each other in such a
manner as to allow a space of from 5 to 6 centimeters between the contents of the
lower grating and the bottom of the grating immediately above.
The said gratings are constructed so as to be able to slide on supports formed by
bars of flat iron, covered with several layers of silicate of soda or potash. In case
of necessity they can be joined together.
The compartment of the fume chambers containing the arrangement of filters
is furnished moreover with an outside hermetically closed door, not only in the
lower part which is a common arrangement, but also in all the compartments at
the top above the space occupied by the gratings. This door is intended for
renewing the filtering substance.
As regards the charcoal of which the filters are composed, it should be soaked
before use in a suitable solution having absorbent and precipitating qualities,
and then dried. This solution is preferably composed of 5% of proto-sulphate
of iron and 5% of permanganate of potash, to 90% of water.
The arrangement of filters described above is devised to collect the particles
of gold from auriferous minerals which particles under an imperfect system of
filtering would be carried away.
In this case the gold evaporates automatically, so to speak, and may be con-
sidered as dissolved in the gases which carry it along. These gases passing up-
wards through the filters deposit the gold on the charcoal, the absorbent qualities
of which are doubled by its precipitating quality owing to the salt with which
it has in some manner been impregnated. It is only necessary to renew the
charcoal from time to time. The gold contained in the charcoal is dissolved out
and then precipitated by the usual means.
When the minerals treated do not contain gold, the filtering arrangement and
its accessories may be omitted and the gases simply introduced into the fume
chambers through the aperture q.
From the fume chambers the gases following the direction indicated by the
arrow, pass into the condenser d by the aperture e whence they are drawn along
the spirals of the screw inside which circulates cold water supplied by the pipe f.
they become condensed by contact with this and with the double-cased cylinder d
between which casings cold water also circulates which is supplied by the pipe g.
The spiral screw as already said, is set in motion by the small hydraulic paddle-
wheel (or other suitable machine) which is operated by the water circulating
in the double casing of the condenser and discharging through the pipe . This
wheel can be made to work faster or slower by regulating the amount of water
by the cock o of the said pipe and by proportionally opening the discharge
cock o¹
In order to wash the condenser, an operation which should be done from time
to time, the cock y of the pipe h is opened. In case of need the pipe serves to
let out the washing water if it is not desired that it should pass through the pro-
duct chambers m.
The condensed arsenious acid as before mentioned is conducted by means of
the spiral into the chamber m through the pipe . When there is a sufficient
weight of condensed products the automatic closing device opens and allows the
This automatic
products to pass into the chamber m, and closes again at once.
closing device consists of a lock or spring bottom or pivotted bottom which opens
under the action of a certain weight, so as to discharge the material weighing on
it & then shuts immediately after having got rid of its weight.
As hereinbefore mentioned it is sometimes necessary to wash the condenser
during the operation; the water used for this washing, as well as that proceeding
from the condensed steam in the cylinder contains dissolved sulphurous acid, and
even sulphuric acid. These weak acids which may be employed after purification
in the preparation of chemical products, before being collected in the reservoir q¹
should pass through the filter o¹¹.
The condensed products as far as the arsenious acid is concerned should be dis-

page_text: tilled a second time in retorts, tubulures or other apparatus in communication
with a condenser.
The gases which have not been condensed, pass out of the condenser by the
aperture, passing through 111 where they are subjected to re-heating, and then
through i and finally arrive at the Glover tower.
When metallic fumes are treated such as those of lead, zinc and the like, it is
well to place a conical filter of flannel at p to collect every trace of the products
which may have escaped condensation.
To increase the draught, a ventilator can in case of need be placed at the end of
the circuit iv in m³.
It is understood that the inventor reserves the right of making any improve-
ments or modifications to his apparatus (the drawings of which only shew one
form of working) which he may find by experience to be useful or necessary.
Having now particularly described and ascertained the nature of my said
invention as communicated to me by my foreign correspondent and in what
manner the same is to be performed, I declare that what I claim is:-
1) An automatic condensing apparatus for arsenious acid and lead, zinc and
metallic fumes in general consisting essentially of a sheet iron cylinder with a
double casing, in which works an Archimedean screw or hollow spiral, surrounding
a hollow axis, between the walls of which cylinder, spiral screw and axis respec-
tively cold water continually circulates, the spiral being set in motion by means
of an hydraulic wheel or other suitable motor, capable of using if needed the
condensing water as motive power, substantially as described.
2) In the condensing apparatus claimed in Claim 1, a high pressure steam
heating device, furnished if necessary with a conical filter (2) communicating
with the interior of the cylinder, for the purpose of heating the gases which com-
ing out of the cylinder are conducted into the Glover tower, substantially as
described.
3) In the condensing apparatus characterized in Claim 1, a discharge pipe (k)
or other similar arrangement with observation hole and swinging automatic
closing device opening into the reservoir (m).
4) In the condensing apparatus characterized in Claim 1, a chamber, reservoir
or box for the products provided with filter (o¹¹) and a discharge door (n).
5) In the condensing apparatus claimed under Claim 1 an arrangement of
filters for receiving the particles of gold carried away by the gases and consisting
of small fragments of wood charcoal resting on leaden wire gratings.
6) The improved condensation process as set forth above applied to arsenious
vapours, lead zinc and metallic fumes in general, substantially as described and
illustrated in the accompanying drawings.
7000
W. P. THOMPSON & Co..
322, High Holborn, London, W.C., Patent Agents for the Applicant.