Improvements in Apparatus for the Electrolytic Extraction of Zinc.
Year: 1899

page_text: Date of Application, 14th Nov., 1899-Accepted, 10th Feb., 1900
Communicated from abroad by SEGIUS STEPANOV, of No. 29, 1, 4, Great Italian
Street, St. Petersburg, in the Empire of Russia.
Improvements in Apparatus for the Electrolytic Extraction of Zinc.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, 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:
:-
The greatest difficulty experienced in the well-known process of extracting
metallic zinc by the electrolytic treatment of sulphate of zinc (zinc-vitriol), con-
sists in the disengagement of free sulphuric acid, which is formed in proportion
as zinc is deposited. In consequence of the noxious action of the sulphuric acid,
the productiveness of this process has therefore never surpassed 0.7 to 0.8
grammes of zinc for one ampere-hour, while the theoretic productiveness is 1.2
grammes.
The action of the sulphuric acid is noxious on the one hand because it dissolves
the deposited zinc, and on the other hand because it diverts one part of the current,
which instead of being utilized to deposit zinc, is expended to decompose tho
water. In order to avoid this disadvantageous action of the acid and to attain
the theoretical production of sine, I have insulated the cathode from the anode
by a film or diaphragm of parchment, which advantageously prevents the dissolu-
tion of the deposited zinc, as also the decomposition of water. For the same
purpose I arrange my apparatus in such a manner, that the liquid is there con-
tinually renewed by two circulating currents: -the one through the spaces or
chambers occupied by the cathode-and the other through the chambers of the
anodes. The liquid having passed through the cathode chambers, and being poor
in zinc, together with the liquid arriving from the anode chambers, which is very
acid, are passed into a common vessel and then into vats filled with calcined ore.
The acid is here saturated with zine till complete neutralisation ensues.
Another hinderance to the success of the electro-metallurgical process for
extracting zinc by electrolysis from solutions of zinc-sulphate, consists in the
phenomenon which is known under the name of arborescence, and presents zinc-
deposits in the form of branchings, which spread, and when the spaces between
the electrodes are limited, make side-contacts by piercing through the diaphragm,
so that it becomes impossible to remove the cathode without damaging the
diaphragm.
In order to avoid the arborescence, I make the edges and the corners of the
cathode-plates round, and to facilitate this rounding I make the said plates thicker
than usual up to 6 millimetres (+ inch).
The cathode plates are made of aluminium, and the anode plates of lead or
silver-plated.
The accompanying drawings shows as a sample, a bath arranged according to
the principles of the present invention and serving for the electrolysis of ZnSO.

page_text: This apparatus is so compact, that when made of a size of 50 x 50 x 40 centimetres
(about 20 x 20 x 16 inches), and having a volume of about 1/8 cub-metre (or
about 5 cub. feet) its productiveness exceeds 40 pounds at 24 hours. The apparu-
tus requires 600 amperes by 3 volts.
In the accompanying drawings:-
Figure 1 shows a longitudinal elevation of the apparatus;
Figure 2 a side elevation;
Figure 3 a plan view;
Figure 4 a vertical section on the line 1-1 of Figure 3;
Figure 5 a horizontal section on the line II-II of Figure 2.
Figure 6 separate detail views of a standard a;
Figure 7 separate detail views of the wooden grating and
Figure 8 separate detail views of an electrode.
A indicates the casing or trunk; B the aluminium cathode; C the lead- or silver-
plated anodes; D the double frames of celluloid between which the films or
diaphragms are fixed. These frames are maintained in place by the grooves cin
the grating a and the grooves d in the grating ])'.
E are the metallic tie-rods with wedged tightening-keys for joining the casing.
F lead channels through which the liquid is passed to the bath.
G gutters through which the exhausted liquid flows away from the bath.
I contact bars of copper for the cathodes and the anodes; each is provided
with a recess filled with mercury, in which are dipped the ends of the conductors,
serving for the series connection of the several apparatus.
a represents an indian-rubber grating or grid provided with grooves for one
end of the frames D, and having recesses for the circulation of the liquid. D' is
a wooden grating or grid also provided with grooves d for the other end of the
frames and having recesses for the circulation of the liquid.
The circulation of the liquid is shown by arrows on Figure 5. The drawings
show clearly all the constructive details of the apparatus, but it is obvious that the
dimensions and the details of construction of this apparatus may be varied.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, as communicated to me by my
foreign correspondent, I declare that what I claim is:-
1. In an apparatus for extracting zinc by electrolysis the employment of parch-
ment partitions or diaphragms between the cathode and anodes and a double cir-
aulating floor of the electrolyte for the electrolysis of sulphate of zine substan-
tially as herein described and illustrated by the accompanying drawings.
2. In an apparatus for extracting zinc by electrolysis, the use of cathode plates
having rounded edges and corners for the purpose hereinbefore set forth.
3. The general construction and arrangement of apparatus for extracting zinc
by electrolysis substantially as herein described and illustrated by the accompany-
ing drawings.
Dated this 14th day of November 1899.
HASELTINE. LAKE & Co.,
45, Southampton Buildings, London, W.C
Agents for the Applicant.