Improvements in and relating to the Treatment of Solutions of Chloride of Zinc for the Purification thereof for Electrolytic Purposes.
Year: 1894

page_text: Date of Application, 24th Nov., 1894
Complete Specification Left, 24th Aug., 1895-Accepted, 28th Sept., 1895
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Treatment of Solutions of
Chloride of Zinc for the Purification thereof for Electrolytic
Purposes.
We, JOHN BROCK Director of The United Alkali Company Limited ARTHur
EDWARD WAREING Chemist and FERDINAND HURTER Ph.D. Chemist all
of G 11 Exchange Buildings, Liverpool in the County of Lancaster do hereby
declare the nature of this invention to be as follows:-
This invention relates to the preparation of solutions (suitable for electrolytic
purposes) of chloride of zinc from impure oxides such as are obtained by roasting
sulphides of zinc (blende), or carbonates of zinc. Such oxides of zinc are usually
contaminated with other metallic oxides. When these impure oxides of zinc are
dissolved in aqueous hydrochloric acid some of the impurities for instance as lead
and iron go into solution as well and render the solution unfit to yield a sufficiently
pure metallic zinc by the electrolytic process. We find that if the exact amount
-of hydrochloric acid which corresponds to the zinc in the impure oxide be employed
for dissolving, that then a solution results which is sufficiently pure.
We proceed
however to dissolve the impure oxide in an excess of hydrochloric acid and then
to agitate the solution so obtained with an excess of the zinc oxide at an elevated
temperature until the impurities have been precipitated. We then allow the solid
particles to subside or remove them by filtration, when the solution is ready for
electrolysing.
Instead of using zinc oxide for the purification we may precipitate hydrated
oxide of zinc from a portion of the solution by milk of lime and use the hydrated
oxide of zinc for the process of purification.
Dated this 24th day of November 1894.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, Agents.
Improvements in and relating to the Treatment of Solutions of
Chloride of Zinc for the Purification thereof for Electrolytic
Purposes.
We, JOHN BROCK, Director of The United Alkali Company Limited, ARTHUR
EDWARD WAREING, Chemist, and FERDINAND HURTER, Ph.D. Chemist, all
of G 11 Exchange Buildings, Liverpool, 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 the preparation of solutions (suitable for electrolytic
purposes) of chloride of zinc from impure oxides such as are obtained by roasting
sulphides of zine (blende) or carbonates of zinc. Such oxides of zinc are usually

page_text: contaminated with other metallic oxides. When these impure oxides of zinc are
dissolved in aqueous hydrochloric acid some of the impurities for instance as lead
and iron go into solution as well, and render the solution unfit to yield a sufficiently
pure metallic zinc by the electrolytic process. We find that if the exact amount
of hydrochloric acid, which corresponds to the zinc in the impure oxide be
employed for dissolving, that then a solution results, which is sufficiently pure.
We proceed however to dissolve the impure oxide in an excess of hydrochloric
acid, and then to agitate the solution so obtained with an excess of the zinc oxide
at an elevated temperature until the impurities have been precipitated. In case
iron is contained in the crude zinc solution in the ferrous condition zinc oxide or
hydrate will not precipitate it. In this case it is necessary to oxidize the solution
by passing through it air, or chlorine gas, or by adding to the solution a little of
the zinc solution derived from the anode compartment of the electrolytic cell
(which is saturated with chlorine). When the whole of the iron is thus oxidized
the oxide will precipitate it. We then allow the solid particles to subside or
remove them by filtration, when the solution is ready for electrolysing.
Instead of using zinc oxide for the purification we may precipitate hydrated
oxide of zinc from a portion of the solution by milk of lime and use the hydrated
oxide of zinc for the process of purification.
It is not advantageous to remove from zinc chloride solutions the whole of the
metallic zinc by electrolysis. We prefer to precipitate from the solutions partially
exhausted by the electrolytic treatment the residue of the zinc as zinc hydrate by
means of lime, and to use this zinc hydrate for purifying fresh solutions.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
-
The treatment of crude zinc chloride solutions obtained by dissolving impure
oxide of zinc in impure hydrochloric acid, by the addition thereto of an excess of
oxide of zinc, or zinc hydrate at an elevated temperature, substantially as and for
the purposes herein before described.
Dated this 23rd day of August 1895.
JOHNSONS & WILLCOX,
Agents.