Improvements in the Treatment of Zinc Ores.
Year: 1889

page_text: Date of Application, 15th June, 1889
Complete Specification Left, 6th Mar., 1890-Accepted, 17th May, 1890
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Zinc Ores.
We, THE ALKALINE REDUCTION SYNDICATE Limited, and ALBERT BERWICK
CUNNINGHAM, Gentleman, both of Hebburn-on-Tyne, in the County of Durham, do
hereby declare the nature of this invention to be as follows:
Our invention relates to the treatment of zinc-ores.
Hitherto in the production of zinc from its ores, only such ores have been used as
are rich in zinc and contain as little silica as possible and no lead, the presence of
lead being so detrimental as to render ores containing it practically valueless as far
as the zinc is concerned.
Our invention consists chiefly in the novel treatment of zinc-ores containing
impurities such as lead and silica, as hereinafter described, whereby we are enabled
to remove practically all such impurities, and at the same time to save the lead, and
the silver or gold if such are present.
In carrying out our invention we fuse the zinc-ore with caustic alkali, preferably
caustic soda, in a reverberatory or other furnace, whereby a fluid mass is produced,
from which the metallic lead (and with it the silver and gold, if such be present,)
is precipitated and drawn off. The remaining fluid mass, which consists mainly of
caustic soda, silicate of soda, a small percentage of sulphide of soda and an enriched
zinc-compound is then drawn off and subsequently lixiviated.
We prefer to effect this lixiviation while the mass is still in a liquid condition, by
running the same into water, whereby the soda compounds are dissolved and the zinc-
compound, enriched by the extraction of the silica and lead, is precipitated.
The soda liquor may be purified from the silica which it contains by the addition
of lime which combines with the silica and precipitates as silicate of lime. The
remaining liquor may be concentrated and used for future charges.
If any iron or copper are present in the zinc-ore, they are not expelled by the
above process, their presence, however, has no detrimental effect during the subsequent
treatment for the production of metallic zinc.
A great advantage of our invention is that the enriched zinc-compound, obtained
as above described, is in such a finely divided condition that, after purification for
the purpose of rendering it perfectly white, it may be used as a pigment.
Dated the 18th day of June 1889.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Zinc Ores.
We, THE ALKALINE REDUCTION SYNDICATE Limited, and ALBERT BERWIOK
CUNNINGHAM, Gentleman, both of Hebburn-on-Tyne, in the County of Durham, 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:
Our invention relates to the treatment of zinc-ores.
Hitherto in the production of zinc from its ores, only such ores have been used
as are rich in zinc and contain as little silica as possible and no lead, the presence of
lead being so detrimental as to render ores containing it practically valueless as far
as the zinc is concerned.
Our invention consists chiefly in the novel treatment of zinc-ores containing

page_text: impurities such as lead and silica as hereinafter described, whereby we are enabled
to remove practically all such impurities, and at the same time to save the lead, and
the silver or gold if such are present.
In carrying out our invention we fuse the zinc-ores with caustic alkali, preferably
caustic soda, in a reverberatory or other furnace.
In practice we find that in heating ores containing, say, thirty per cent. (30%) of
zinc and thirty per cent. (30%) of lead it is advantageous to employ fifty per cent.
(50%) by weight of caustic soda, that is to say, to a charge of five hundred weights
(5 cwts.) of ore we should add two and a half hundred weights (2 cwts.) of caustic
soda.
It is obvious that the amount of soda used depends entirely upon the refractory
nature of the ore under treatment, for instance, an ore containing a large amount of
silica requires more soda than an ore rich in zinc and lead and containing less
silica.
As a result of the fusion hereinbefore referred to a fluid mass is produced, from
which the metallic lead (and with it the silver and gold, if such be present,) precipi-
tates and is drawn off. The remaining fluid mass, which consists mainly of caustic
soda silicate of soda, a small percentage of sulphide of soda and an enriched zinc
compound is then drawn off and subsequently lixiviated.
We prefer to effect this lixiviation while the mass is still in a liquid condition, by
running the same into water, whereby the soda compounds are dissolved and the zinc-
compound, enriched by the extraction of the silica and lead, is precipitated.
The soda liquor may be purified from the silica which it contains by the addition
of lime which combines with the silica and precipitates as silicate of lime. The
remaining liquor may be concentrated and used for future charges.
If any iron or copper are present in the zinc-ore, they are not expelled by the
above process, their presence, however, has no detrimental effect during the subsequent
treatment for the production of metallic zinc.
A great advantage of our invention is that the enriched zinc-compound, obtained
as above described, is in such a finely divided condition that, after purification for
the purpose of rendering it perfectly white, it may be used as a pigment.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :
The method of treating zinc-ores consisting in fusing the same with caustic alkali
to produce a fluid mass, from which the chief impurities are precipitated in a
metallic condition; drawing off such metallic impurities, and lixiviating the remaining
soda compounds, whereby the soda is dissolved and a compound rich in zinc
precipitated, the soda liquor being subsequently regenerated, if desired, substantially
as described.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.