Improvements in the Combined Electrolytic and Leaching Treat- ment of Zinc-bearing Ores and Zinc-bearing Products.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Combined Electrolytic and Leaching Treat-
ment of Zinc-bearing Ores and Zinc-bearing Products.
I, EDGAR ARTHUR ASHCROFT, of "Maycroft," Newcommen Street, Newcastle, in the
Colony of New South Wales, Metallurgical Engineer, do hereby declare the nature of
this invention to be as follows:--
My present invention relates to improvements in the process for the combined
electrolytic and leaching treatment of zinc-bearing ores and zine-bearing products
which I have more particularly described in Letters Patent No. 13,850 entitled "An
improved process of treating zinc-bearing refractory ores and zinc-bearing products,"
dated 18th July, 1894, and in Letters Patent No. 13,534 entitled "Improvements in
the treatment of zinc-bearing ores and zinc-bearing products," dated 13th July, 1895,
which have been granted to me.
The improvements the subject of my present invention have for their object the
cheapening of the process described in the Letters Patent herein before mentioned
and provide a method of obtaining a ferric salt solution suitable for leaching the zinc.
ores or products (roasted if necessary) without the use of iron anodes.
In the process described in the Letters Patent hereinbefore mentioned I used.
soluble iron anodes in order to obtain an iron salt solution whose iron content was
raised to the ferric state in a subsequent stage of the electrolytic process. In place,
of such soluble iron anodes employ in my present invention carbon or other.
insoluble anodes, the compartments of the vats which previously were iron anode.
compartments thus becoming carbon anode compartments, and in place of the
solution which in the process described in the Letters Patent herein before
mentioned circulated in the iron anode compartment, I circulate a solution of iron
(which may as mentioned later also hold in solution some zinc) obtained in the
following manner:-A solution of iron is first obtained by dissolving either in:
sulphuric or hydrochloric acid metallic iron in any cheap form such as scrap, and the
iron content of such solution is oxidized to the ferric state by circulating the same in
the carbon anode compartments. The solution proceeding from such carbon anode
compartments is circulated in contact with metallic iron in any cheap form such as
scrap, whereby the ferric salts are reduced to ferrous salts and some of the metallio
iron is simultaneously dissolved. After such circulation the iron solution is again
circulated in the carbon anode compartments whereby the whole of the iron is
oxidized into the ferric condition. If necessary, in order to meet the other stages of
the process described in the Letters Patent herein before mentioned, the iron solution
may be again circulated in contact with metallic iron and again circulated in the
carbon anode compartments and so on, until a sufficient quantity of iron in the ferric
state is contained in the solution.
The metallic iron may be stacked in vats or in any convenient way.. Into
the vats may also be introduced scrap zinc which becomes dissolved in the iron
solution.

page_text: The advantages of these improvements are that although the amount of electrical
power required is somewhat increased by the employment of insoluble anodes in the
vats where formerly iron anodes were employed the requisite iron is dissolved from a
less expensive raw material and any zinc contained in the scrap is also utilized.
Polarization and the liberation of, free acid or chlorine at the carbon anodes .is
prevented by the presence of ferrous salts in the anolytes and the oxidation of ferrous
salts yields its quota of energy to the electrical circuit so that the additional energy
required is not to be weighed commercially in comparison with the reduction in cost
of the iron and the recovery of waste zinc.
Dated this 23rd day of March 1897.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
Improvements in the Combined Electrolytic and Leaching Treat-
ment of Zinc-bearing Ores and Zinc-bearing Products.
I, EDGAR ARTHUR ASHCROFT, of "Maycroft," Newcommen Street, Newcastle, in the
Colony of New South Wales, Metallurgical 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:-
My present invention relates to improvements in the process for the combined
electrolytic and leaching treatment of zinc-bearing ores and zinc-bearing products
which I have more particularly described in Letters Patent No. 13,850 entitled "An
improved process of treating zinc-bearing refractory ores and zinc-bearing products,"
dated 18th July 1894 and in Letters Patent No. 13,534 entitled "Improvements in
the treatment of zinc-bearing ores and zinc-bearing products," dated 13th July 1895
which have been granted to me.
The improvements the subject of my present invention have for their object the
cheapening of the process described in the Letters Patent herein before mentioned,
and provide a method of obtaining a ferric salt solution suitable for leaching the
zinc ores or products (roasted if necessary) without the use of iron anodes.
In the process described in the Letters Patent hereinbefore mentioned I used soluble
iron anodes in order to obtain an iron salt solution whose iron content was raised to
the ferric state in a subsequent stage of the electrolytic process. In place of such
soluble iron anodes I employ in my present invention carbon or other insoluble
anodes the compartments of the vats which previously. were iron anode compartments
thus becoming carbon anode compartments, and in place of the solution which in the
process described in the Letters Patent herein before mentioned circulated in the iron
anode compartment, I circulate a solution of iron (which may as mentioned later also
hold in solution some zinc) obtained in the following manner. A solution of iron is
first obtained by dissolving metallic iron in any cheap form such as "scrap " either
in sulphuric acid (in the case for example where.Solution No. 3 described in the
Specification of the before mentioned Letters Patent No 13534 dated July 13th 1895
is used) or in hydrochloric acid, and the iron content of such solution is oxidised to
the ferric state by circulating the same in the carbon anode compartments. The
solution proceeding from such carbon anode compartments is circulated in contact
with metallic iron in any cheap form such as "scrap" whereby the ferric salts are
reduced to ferrous salts and some of the metallic iron is simultaneously dissolved.
After such circulation the iron solution is again circulated in the carbon anode
compartments whereby the whole of the iron is oxidized into the ferric condition.
If necessary in order to meet the other stages of the process described in the Letters

page_text: The ferric chloride re acts with the scrap iron to form ferrous chloride
Fe, Cl + Fe
=
3 (Fe Cl₂).
From a consideration of the above equations it will be seen that the quantity of
ferric chloride formed is in excess of the quantity requisite to re form the initial
quantity of ferrous chloride. Hence at each cycle a quantity of ferric chloride viz.
one third of the quantity formed during such cycle may be withdrawn which serves
for the purpose of leaching more ore.
It will be readily seen that the process described above can be arranged to work as
a cyclic process by continuously diverting a suitable proportion of the erric salt solu-
tion to the vats B3 and B and then restoring it to the main circulation.
The advantages of these improvements are that although the amount of electrical
power required is somewhat increased by the employment of insoluble anodes in the
vats, where formerly iron anodes were employed the requisite iron is dissolved from a
less expensive raw material and any zinc contained in the scrap is also utilized.
Polarization and the liberation of free acid or chlorine at the carbon anodes is
prevented by the presence of ferrous salts in the anolytes and the oxidation of ferrous
salts yields its quota of energy to the electrical circuit so that the additional energy
required is not to be weighed commercially in comparison with the reduction in cost
of the iron and the recovery of waste zinc.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The improved process for the treatment of zinc bearing ores and zinc bearing
products, consisting in leaching such ores or products with a solution containing either
ferric sulphate or ferric chloride, electrolytically depositing zinc from the zinc bearing
solution contained as the result of such leaching, and simultaneously with such
electro-deposition regenerating such solution by passing it over metallic iron (not
operating as anodes) substantially as described.

page_text: 2. The improved process for the treatment of zinc bearing ores and zinc bearing
products consisting in first circulating around the cathode compartments of an
electrolytic system of vats a zinc bearing solution free or nearly free from iron, next
mixing therewith a ferrous chloride or sulphate solution and causing the mixture to
circulate around the carbon anode compartments of the same system of vats to raise
the iron content to the ferric state, then deflecting a suitable quantity of the total
volume of the solution, leaving such anode compartments into vats containing scrap
iron and after a sufficient amount of iron has been taken up returning it to the
aforesaid carbon anode compartments substantially as and for the purposes specified.
3. The improved process for the treatment of zinc bearing ores and zinc bearing
products substantially as described and arranged to work cyclically.
Dated this 23rd day of December 1807
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.