Improvements in the Utilization of Zinc Blende for Obtaining Metallic Zinc and Sulphur, and in Effecting the Decomposition of Common Salt for the Production of Soda and Chlorine.
Year: 1894

page_text: Date of Application, 24th Nov., 1894
Complete Specification Left, 21st Aug., 1895–Accepted, 21st Sept., 1895
PROVISIONAL SPECIFICATION.
Improvements in the Utilization of Zinc Blende for Obtaining
Metallic Zinc and Sulphur, and in Effecting the Decomposition
of Common Salt for the Production of Soda and Chlorine.
We Jonx BROCK, Director of The United Alkali Co. Limited, ARTHUR
EDWARD WAREING, Chemist, and FERDINAND HURTER, Ph.D., Chemist, all of
G11 Exchange Buildings, Liverpool in the County of Lancaster do hereby declare
the nature of this invention to be as follows.-
"
This invention has for its object the utilization of zinc blende so as to obtam
therefrom the sulphur and the metallic zinc and to effect at the same time and
indirectly by means of the blende the decomposition of common salt and to produce
soda and chlorine therefrom.
We roast the zinc blende so as to obtain oxide of zine and sulphurous
acid gas.
The sulphurous acid gas we conduct into vitriol chambers, where, by admixture
with nitrogen oxides and steam, we produce sulphuric acid.
We then decompose common salt by means of the sulphuric acid and we thus
obtain sulphate of soda and hydrochloric acid gas.
From the sulphate of soda we produce soda by the "Leblanc "
process and from
the insoluble residue of calcium sulphide produced in that process, we obtain the
sulphur formerly contained in the blende, by treating the calcium sulphide with
carbonic acid gas in closed vessels and burning the sulphuretted hydrogen resulting
from this operation with a limited amount of air in what are known as "Claus
kilus."
The hydrochloric acid evolved during the decomposition of the sodium chloride
with sulphuric acid we utilise for the manufacture of zine chloride. We treat the
residue from the calcination of the zinc blende, namely the oxide of zinc, with
hydrochloric acid.
We either pass the hydrochloric acid gas mixed with steam if necessary, over
the oxide of zinc moistened with water, in a suitable apparatus and collect the
solution of zinc chloride so formed Or we first condense the hydrochloric acid
gas with water and use the liquid hydrochloric acid for dissolving the zinc oxide
(the residue of the blende).
By whichever of these methods the solution of zine chloride is prepared we
subject it to the process of electrolysis in order to produce metallic zine and
chlorine gas.
We employ electrolytic cells connected either in parallel or in series, cach cell
having two compartments separated by a porous partition, one compartment
containing the anode of carbon, the other compartment containing the cathode of
either iron or zinc. The anode compartment is so arranged that the chlorine
evolved at the anode may be collected and does not escape into the atmosphere.
We fill these cells with the strong solution of zinc chloride and pass the electric
current from a suitable generator of electricity through them, when metallic inc
is deposited at the cathode, and chlorine is produced at the anode.
We interrupt the electrolysis when the solution in the cathode compartment has
deposited about 70 to 90 per cent. of the zinc originally contained therein, as the
solution then begins to offer too much resistance to the passage of the electric

page_text: current. Instead of superintending the process in each separate compartment, we
cause the zinc solution to flow through several compartments in succession, so as to
flow as a strong solution into the first cathode compartment, thence through
successive cathode-compartments into the last of a series, from which the solution
is finally withdrawn, having deposited on its way through the several compartments
about 70 to 90 per cent. of the zinc it contained. When sufficient zinc has been
deposited in the cell we collect it, and remelt it. If cathodes of metallic zine
have been employed, we prefer to melt the cathode plate together with the zine
deposited upon it.
The weak solution of zinc chloride, flowing from the last cathode compartment
of a series, we treat with fresh hydrochloric acid gas and afterwards with oxide of
zine (roasted blende) when it may again be fed into the first compartment of a
series. Or we may treat the weak solution of chloride of zinc with milk of lime
so as to precipitate the zine as hydrate, and then use the zinc hydrate for the
saturation of fresh hydrochloric acid together with the impure oxide.
The solution of zinc chloride in the anode compartment also gradually becomes
weaker, though not so fast as the solution in the cathode compartment. It must
therefore also be renewed. This may be done in a similar manner by circulating
the solution-through several anode compartments, and allowing fresh solution to
enter one anode compartment whilst the weaker solution flows away from another
compartment of a series. This weak solution contains chlorine in the free state
and before the solution is allowed to enter the cathode compartments, it is to be
freed from the chlorine by agitating it with, or filtering it through, zinc blende.
We prefer to employ all the zine solutions in a fairly pure condition.
The chlorine evolved at the anode we convey to suitable apparatus for the
production of bleaching powder or of chlorates or other chlorine compounds, or
for the production of liquid chlorine
Dut
Vavambo 1801
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, WC, Agents.
in the Utilization of Zinc Blende for
Improvements
Obtaining
Metallic Zinc and Sulphur, and in Effecting the Decomposition
of Common Salt for the Production of Soda and Chlorine.
We, JOHN BROCK, Director of The United Alkali Company Limited, ARTHUR
EDWARD WAREING, Chemist, and FERDINAND URTER, Ph D Chemist, all
of G 11 Exchange Buildings Laverpool, 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 has for its object the utilisation of zinc blende so as to obtain
therefrom the sulphur and the metallic zine and to effect at the same time and
indirectly by means of the blende the decomposition of common salt and to
produce soda and chlorine therefrom.
litherto when zinc blende has been utilised for effecting the decomposition of
common salt, the metallic zine had to be obtained from the roasted blende by
costly metallurgical processes, and the chlorine of the salt was liberated by the
usual process first as hydrochloric acid, which was afterwards decomposed either by
the Deacon or the Weldon process at considerable expense.
It has also been proposed to utilize zinc blende for effecting the decomposition
of common salt by mixing the blende with the salt and caleining the mixture so as

page_text: to produce sodium sulphate and zinc chloride. These were afterwards dissolved in
water and the sodium sulphate was separated by concentrating and salting out.
The chloride of zinc solution was then submitted to electrolysis so as to obtain
metallic zinc and chlorine.
But the calcination of the mixture of salt and blende is difficult and yields
unsatisfactory results.
Our improved mode of utilizing zinc blende for effecting the decomposition of
common salt is intended to obviate some of the difficulties and expenses of the older
processes.
We roast the zine blende, so as to obtain oxide of zinc and sulphurous acid gas,
in kilns suitable for that purpose.
The sulphurous acid gas we conduct into vitriol chambers, where, by admixture
with nitrogen oxides and steam, we produce sulphuric acid as is well understood.
We then decompose common salt by means of the sulphuric acid and we thus
obtam sulphate of soda and hydrochloric acid gas which may be done by the
ordinary methods.
From the sulphate of soda we produce soda by the "Leblanc"
process, and from
the insoluble residue of calcium sulphide produced in that process, we obtain the
sulphur formerly contained in the blende, by treating the calcium sulphide with
carbonic acid gas in closed vessels and burning the sulphuretied hydrogen resulting
from this operation with a limited amount of air in what are known as
"Claus
kilns.'
The hydrochloric acid evolved during the decomposition of the sodium chloride
with sulphuric acid we utilise for the manufacture of zinc chloride. We treat the
residue from the calciuation of the zinc blende, namely the oxide of zinc, with
hydrochloric acid. We either pass the hydrochloric acid gas, mixed with steam if
necessary, over the oxide of zinc, moistened with water, in a suitable apparatus and
collect the solution of zinc chloride so formed, or we first condense the hydro-
chloric acid gas with water and use the liquid hydrochloric acid for dissolving the
zinc oxide (the residue of the blende).
By whichever of these methods the solution of zinc chloride is prepared we
subject it to the process of electrolysis in order to produce metallic zinc and
chlorine gas.
We employ electrolytic cells connected either in parallel or in series, each cell
having two compartments separated by a porous partition, one compartment
containing the anode of carbon, the other compartment containing the cathode of
either iron or zinc. The anode compartment is so arranged that the chlorine
evolved at the anode may be collected and does not escape into the atmosphere.
We fill these cells with the strong solution of zinc chloride and pass the electric
current from a suitable generator of electricity through them, when metallic zinc is
deposited at the cathode, and chlorine is produced at the anode.
We interrupt the electrolysis when the solution in the cathode compartment has
deposited about 70 to 90 per cent. of the zine originally contained therein, as the
solution then begins to offer too much resistance to the passage of the electric
current. Instead of superintending the process in each separate compartment, we
cause the zinc solution to flow through several compartments in succession, so as to
flow as
a strong solution into the first cathode compartment, thence through
successive cathode-compartments into the last of a series, from which the solution
is finally withdrawn, having deposited on its way through the several compartments
about 70 to 90 per cent. of the zinc it contained. When sufficient zinc has been
deposited in the cell we collect it, and remelt it.
The weak solution of zinc chloride, flowing from the last cathode compartment
of a series, we treat with fresh hydrochloric acid gas and afterwards with oxide of
Zinc (roasted blende) when it may again be fed into the first compartment of a
series. Or we may treat the weak solution of chloride of zinc with milk of lime so
as to precipitate the zinc as hydrate, and then use the zinc hydrate for the
saturation of fresh hydrochloric acid together with the impure oxide,

page_text: The solution of zinc chloride in the anode compartment also gradually becomes
weaker, though not so fast as the solution in the cathode compartment. It must
therefore also be renewed. This may be done in a similar manner by circulating
the solution through several anode compartments, and allowing fresh solution to
enter one anode compartment whilst the weaker solution flows away from another
compartment of a series.
We prefer to cause the flow of liquid in the anode compartment to be in opposite
direction to the flow of liquid in the cathode compartment, for example, if the
cathode solution flows from No 1 cell to No. 2 cell, we cause the anode solution to
flow from No. 2 cell to No. 1 cell This weak solution from the anode compartment
contains chlorine in the free state and before the solution is allowed to enter the
cathode compartments, it is to be freed from the chlorine by agitating it with, or
filtering it through, zinc blende.
We prefer to employ all the zine solutions in a fairly pure condition.
The chlorine evolved at the anode we convey to suitable apparatus for the
production of bleaching powder or of chlorates or other chlorine compounds, or for
the production of liquid chlorine
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 utilization of zine blende for effecting the decomposition of common salt so
as to obtain metallic zinc, sulphur, chlorine, and sulphate of soda producing
sulphuric acid and oxide of zinc from the zinc blende, using the sulphuric acid in
the manufacture of sulphate of soda and hydrochloric acid from salt, dissolving the
oxide of zine in hydrochloric acid and electrolysing the zinc solution so as to obtain
metallic zine and chlorine all substantially as herein before described.
Dated the 21st day of August 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.