An Improvement in Electrolytic Apparatus.
Year: 1899

page_text: Date of Application, 1st June, 1899-Accepted, 29th July, 1899
COMPLETE SPECIFICATION.
An Improvement in Electrolytic Apparatus.
I, JOHN GUSTAF ADOLF RHODIN, Analytical Chemist and Electrical Engineer,
Owner of the Physico-Chemical Laboratory, of No. 47, Victoria Buildings, Man-
chester, in the County of Lancaster, 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:-
This invention relates to electrolytic apparatus for effecting decomposition of
an alkali sulphate such as sodium sulphate so as to produce caustic alkali and
copper sulphate which may afterwards be decomposed so as to produce sulphuric
acid and deposit metallic copper.
For this purpose an electrolytic cell is divided by a porous partition into two
compartments. The one or anode compartment is charged with sodium sulphate
in which there is an anode of copper, connected to the positive terminal of a
source of electricity. The other or cathode compartment contains an aqueous
solution of caustic soda and has in it as cathode a layer of mercury connected to
the negative terminal of the source of electricity. When the cell is put in circuit,
the rolium sulphate is decomposed, its sulphuric acid combining with a portion
of the copper anode to form copper sulphate while its sodium passes through the
porous partition to the cathode compartment where it forms an amalgam with the
mercury and then becomes oxidised so as to form caustic soda, by oxygen from the
water of the solution in the cathode compartment hydrogen being liberated and
escaping. Thus the copper sulphate solution in the anode compartment and the
caustic soda solution in the cathode compartment become stronger and stronger and
may from time to time be wholly or partly removed or sodium sulphate may be
continuously fed into the anode compartment, copper sulphate solution being
drawn off therefrom and caustic soda solution being drawn from the cathode
compartment.
Fig. 1 of the accompanying drawings is a section of apparatus according to
this invention, and Fig. 2 is in one half a top plan, the other half is a sectional
plan on the line A of. Figure 1.
Within a basin-like vessel a the bottom of which has ribs b inclined to radii
and projecting a little upwards, a smaller basin-like vessel e fixed on a vertical
shaft is caused to revolve by any convenient means such as a belt acting on a
pulley on the shaft d. The lower part of the vessel e consists of ribs with openings
between them carrying a porous diaphragm e which slopes down towards a central
opening over a well f formed in the base of the vessel a. The shaft d revolves
in a bearing g and has on it an insulated ring on which bears a brush connected
by a conductor to the positive terminal of a source of electricity. From the
ring are suspended several copper gratings which constitute the anode. A
layer of mercury k covers the lower part of the vessel a over which is, at first,
water, afterwards becoming solution of caustic soda, while in the vessel is sodium
sulphate. A conductor connects the mercury to the negative terminal of the
source of electricity. On the cell being put in circuit and the shaft d being caused
to revolve, the copper anodes j are gradually dissolved by the sulphuric acid

page_text: resulting from decomposition of the sodium sulphate producing copper sulphate,
while the sodium passing through the porous diaphragm e forms an amalgam with
the mercury. The amalgam is caused by the downwardly projecting ribs m
forming compartments on the underside of the basin c, as it revolves in the direc-
tion of the arrow to travel along the spaces between the ribs towards the
periphery of the vessel a and during its travel the sodium becomes oxidised
forming caustic soda which mixes with the solution in the annular space around c,
while the mercury, being heavier when freed from the sodium, flows back towards
the centre to take up fresh sodium. When the contents of c consist mostly of
copper sulphate, while those of the annular space around it consist mostly of caustic
soda solution, these two compartments may be emptied by opening cocks in
pipes P. The copper sulphate can be electrolytically decomposed producing
sulphuric acid and metallic copper. When, in the first process, crude or impure
copper is used as anode the impurities are mostly deposited in the well f, and can
be removed on raising the vessel c. The cocks on the pipes p q may be so
adjusted as to keep the flow of copper sulphate and caustic soda continuous, sodium
sulphate being continuously fed into c.
Although sodium sulphate has been mentioned as the alkali sulphate treated,
the bisulphate might also be dealt with in the same way, also potassium sulphate
or bisulphate and, instead of copper being employed as anode, other metals which
can be similarly dissolved in the sulphuric acid liberated from the alkali sulphate
can be treated in the same way.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
For decomposition of alkali sulphate and production of sulphate of copper or
other metal and of caustic alkali, electrolytic apparatus constructed and operating,
substantially as described.
000
ABEL & IMRAY,
Agents for the Applicant.