Improvements in and connected with the Production of Chlorine and Zinc,
Year: 1895

page_text: Date of Application, 22nd Aug., 1895
Complete Specification Left, 22nd May, 1896-Accepted, 27th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in and connected with the Production of Chlorine
and Zinc,
I, FARNHAM MAXWELL LYTE, of 60, Finborough Road, South Kensington,
in the County of London, Chemical Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention relates to a process having for its object the production of
chlorine together with the separation of metallic zinc, lead and silver from the
mixed ores of blende and galena or by the treatment of blende alone.
The mixed ore is first purified from the blende it contains by the known method
of converting the blende into crude zinc sulphate (white vitriol) by the calcination
of the powdered ore at a low temperature while exposed to the air and frequently
turned over and by the subsequent lixiviation of the product in order to extract
the soluble sulphates formed.
The crude zinc sulphate so formed is converted into zinc chloride by the addition
of a soluble chloride, say, calcic or sodic chloride, sufficient in amount to convert
all the sulphates present into chlorides, and the chlorides thus formed are purified
from iron and any other impurities except magnesic chloride which it may contain
by oxidation with calcination, or in the usual manner, the calcic or sodic sulphate
being separated by evaporation and cooling if necessary. The purification of the
crude zinc sulphate may also be carried out in like manner, if desired, before its
conversion into chlorides.
The zinc chloride then being deprived of its water of solution by evaporation
and brought into a state of igneous fusion, the heating is to be carried to a tem-
perature slightly above the melting point of zinc and it is then electrolysed for, the
production of chlorine and metallic zinc, an anode of carbon being used and the
molten zinc forming the cathode.
The residual galena having been thus deprived of its admixture of blende, or
nearly so, may be smelted and treated in the usual manner for the extraction of any
lead or precious metal it may contain. This process may also of course be applied
to the production of metallic zinc and chlorine from blende alone.
Dated the 22nd day of August 1895.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
Improvements in and connected with the Production of Chlorine
and Zinc.
I, FARNHAM MAXWELL LYTE, of 60, Finborough Road, South Kensington,
in the County of London, Esquire, 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 a conjoint process, having for its object the production.

page_text: of chlorine together with the separation of metallic zinc, lead, and silver from
mixed ores of blende and galena, or for the treatment of blende alone to produce
chlorine and zinc.
The mixed ore, if that is the ore to be treated, is first purified from the blende it
contains by the known method which is at present employed for that purpose, viz.
calcination at a low temperature and extraction of the basic zinc sulphate so formed
by lixiviation with dilute sulphuric acid. If blende alone be dealt with it may
be treated in the same way, or zinc sulphate formed in any known way may be
employed.
The crude zinc sulphate may be purified in the usual manner from the other
metallic sulphates and any other impurities it contains. Magnesic sulphate,
however, is difficult of separation, but the presence of magnesium in small
proportion is not injurious.
It is then neutralized if acid, and converted into zinc chloride by an addition to
its solution, which has been sufficiently concentrated if requisite, of an equivalent
amount of calcic chloride or sodic chloride in the latter case, the separation of the
sodic sulphate formed being assisted by refrigeration, as is described by Gmelin,
Watts, Wurtz and others, or zinc chloride produced from calamine as described in
the Specification of Patent No. 11,724 of 1894 may be employed. The zinc
chloride may also be produced from the crude zinc sulphate before its purification,
and subsequently purified from metallic impurities, or a solution of zinc chloride
may be produced in any other way.
However it may have been formed, the zinc chloride, having been evaporated, is
brought to such a temperature as to expel, as far as may be, the last traces of water.
Towards the end of the evaporation, which requires a high temperature to complete
it, part of the zinc chloride is decomposed with formation of zinc oxide and
evolution of hydrochloric acid. The concentration of the zinc chloride may be per-
formed in any suitable apparatus such for example as that employed by Webb
for the concentration of sulphuric acid. The addition of metallic zinc will be
found to be of some assistance during the operation.
The zinc chloride may now be separated by distillation and the oxychloride,
together with any impurities left in the retort, may be dissolved in dilute sulphuric
acid and added to the batch of crude zinc sulphate used in the succeeding operation,
all the water being expelled or decomposed before the distillation of the zinc
chloride commences, or it may be rendered anhydrous by electrolysis.
The zinc chloride is now decomposed by electrolysis, an anode of carbon, a
cathode of fused zinc, with the fused zinc chloride as the electrolyte, completing
the electrolytic cell.
As a fused zinc cathode is here employed, the metallic zinc from the electrolysis
is taken up by and incorporated in it as fast as it is deposited.
By these means there can be no fear of the production of the useless powdery
deposit of metallic zinc mentioned by Siemens as being formed when solutions of
zinc salts are electrolysed by a current of any more intensity than five ampères per
square foot of cathode as mentioned in the Specification of Patent No. 13,434 of
1895 (Siemens). The cathode always thus continues to present a clean metallic
surface, no matter what may be the current density employed and by working in
series the speed of the operation may be increased, while the cost is greatly
diminished, so that a considerable economy is obtained. On the E.M.F. being
now increased, if necessary, the zinc chloride will in its turn be decomposed with
deposition as before of metallic zinc and an evolution of chlorine.
In proportion as the metallic zinc accumulates it may be caused to run off
automatically by means of a syphon, like the lead in the electrolysis of fused lead
chloride as in the apparatus described in the Specification of Patent No. 7594
of 1893, and the chlorine may be liquefied by cold or pressure or both and stored
in metal cylinders or otherwise disposed of while the residual galena from the
treated ore, having thus been deprived of its blende, or nearly so, may be smelted

page_text: and treated in the usual manner for the recovery of the lead and any precious.
metal it may contain.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
-
1. The described process for the production of chlorine and the separation of
metallic zinc, lead and silver from the mixed ores of blende and galena or from.
blende alone, such process consisting in first converting the blende into crude zinc
sulphate, purifying the sulphate and converting it into the chloride (or converting
the sulphate into the chloride and purifying the chloride) evaporating the solution,
fusing the zinc chloride, heating it to a temperature slightly above the melting
point of zinc, and then separating the chlorine and zinc by electrolysis, an anode.
of carbon, and a cathode of fused metallic zinc being employed, in the manner
substantially as described.
2. The process for the production of chlorine and metallic zinc from zinc
chloride, such process consisting in evaporating the chloride and, after heating it
to a temperature a little over that of the melting point of zinc, separating the
chlorine and zinc by electrolysis, an anode of carbon and a cathode of fused
metallic zinc being employed in the manner substantially as described.
Dated this 22nd day of May 1896.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.