Improvements in the Extraction of Zinc from its Ores.
Year: 1898

page_text: Date of Application, 27th July, 1898
PROVISIONAL SPECIFICATION.
Improvements in the Extraction of Zinc from its Ores.
I, JOHN ARMSTRONG, of 13, Sherborne Lane, in the County and City of
London, Metallurgical Chemist, do hereby declare the nature of this invention
to be as follows:-
The metallurgy of zinc hitherto conducted has been a tedious, long and
expensive process especially if extracted from the ores of blende or silicate of
zinc, owing to the fact that these ores will not give up their zinc with carbon,
all the ores of zinc except the oxide have to be roasted and that of blende abso-
lutely otherwise it is impossible to extract the metal.
My present invention is an improved method whereby I can expeditiously
and more perfectly extract the metal contents from the ore and is as follows:-
1st. If zinc blende is the ore that is to be treated, I either add a sufficient
quantity of carbonate of soda or other salt of soda or potassium to the raw ore
and distil in the usual way, or I partly or wholly calcine the blende when a
great saving of soda or potassa will result.
If the zinc is in the form of calamine or silicate or oxide of zinc I do not
are in combination but
generally roast the ore unless some foreign matters
simply mix carbonate of soda or carbonate of potassa or other salt of either of
the alkali metals with the ore and distil in the usual way, with the result that
instead of taking from 10 to 24 hours as at present for the zinc to distil I find
that I can accomplish the same in three to four hours with a larger yield of
metal.
Although I have specified carbonate of soda, other salts of either soda or
potassa find with certain modifications will give results almost similar,
namely, sodium hydrate or sodium nitrate, sodium acetate, sodium sulphate or
sulphide, the latter may be used in combination with lime or iron, lime and
alumina are also very usefully employed with most of the mixtures.
The operations are conducted in an ordinary zinc distillation furnace by
means of retorts and the ordinary condensing apparatus used in zinc distillation.
In all the above mixtures carbon must be added in any form such as coal,
coke, etcetera, and the ingredients are preferably ground to an extreme fineness,
say 30 mesh sieve being used to pass the mixture through, although the finer
the better so that the mixture may be as homogeneous as possible. The mixture
is slightly damped with water before being placed in the retorts to prevent
dusting.
The alkaline salts are afterwards recovered from the retort by lixiviation for
re-use or by using special precautions to prevent the condensation of sodium in
the tubes and adding extra carbon and a separate condensing apparatus for the
sodium, metallic sodium can also be collected.
220
1900
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.

page_text: Improvements in the Extraction of Zinc from its Ores.
I, JOHN ARMSTRONG, late of 13, Sherborne Lane, but now of. 46; Lombard
Street, in the County and City of London, Metallurgical Chemist, do hereby
declare the nature of this invention' and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement-
-
In my Specification No. 22361 of 1896, I described a process for the smelting
of refractory sulphide ores containing zinc, further experiments have shown
me that in a somewhat modified form that process can be applied to smelting
almost any variety of zinc ore.
In the metallurgy of zinc and in ores containing zinc, great difficulty has
been hitherto experienced in the extraction of the metal.
By my present invention, I can expeditiously and more perfectly extract the
metal contents from the ore. It is as follows:-
1st. If zinc blende is the ore that is to be treated, I add a sufficient quantity
of carbonaceous matter and of carbonate, nitrate, hydrate or sulphide or other
easily disassociated salt of soda or potassa, such as acetate or sulphate and flux
it in a furnace out of contact with air in the manner and substantially the pro-
portions of alkali salt, carbon and ore respectively as set forth in my aforesaid
patent, or I partially roast the blende first when a considerable saving is
effected in the amount of alkali salt required.
2nd. If the zinc is in the form of calamine or silicate of zinc, I do not gene-
rally roast the ore unless some foreign matters are in combination, but simply
mix carbonaceous matter and carbonate of soda or potassa or other salt as above
of either of the alkali metals with the ore and distil in the retorts in the usual
way with carbon, with the result that instead of taking from 10 to 24 hours as
at present for the zinc to distil, I find that I can accomplish the same in from
3 to 4 hours with a larger yield of metal.
But in order to obviate fluxing going on in the retorts, I prefer to first flux
the ore with the alkali metal salt and a small quantity of carbonaceous matter
in a reverberatory or other furnace and then run out the contents either into
water or pile it upon a heap to weather, then lixiviate out the alkali with.
water, dry, and then distil the residue in the ordinary way with carbon (which
should be finely ground and intimately mixed with the ore). By this means
the alkali is recovered to be converted for re-use, and the retorts are saved from
fluxing and therefore last longer. Should the zinc ore contain any precious
metals such as silver and gold, as is frequently the case, I add some form of
lead, such as metallic lead or galena to a sulphide ore or oxide or carbonate of
lead to calamine or silicate ore, add alkali metal salt as above stated and car-
bonaceous matter all finely powdered and mixed and I flux the whole in a
reducing atmosphere; in this way reducing the lead which will contain
the precious metal. The lead is tapped off from the furnace as metal, the zinc
remaining in the slag. This latter is run out of the furnace and treated as
above described.
In the above process, if sodium sulphate or sulphide be used it is desirable to
add lime or iron; alumina and lime are also very usefully employed with most
of the mixtures especially when there is much silica present. In all the mixtures
carbon must be added in any form such as coal, coke, etcetera, and the ingre-
dients are preferably ground to an extreme fineness sufficiently to enable it say
to pass through a sieve of 30 to 60 meshes to the inch, the finer the better.

page_text: Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is;
1. The application of a modification of my process as described in Patent
No. 22361 of 1896 to the smelting of ordinary ores of zinc, which consists in
furnacing raw or partially or wholly roasted ore with an alkali metal salt such
as described, and with or without fluxing matter, lixiviating the mixture so as
to separate the alkali salts, and then distilling with carbon, substantially as
described.
2. The improvement in the process of obtaining zinc from zinc ores mattes
or slags and carbon by distillation, which consists in adding to and thoroughly
mixing with these ingredients the finely divided salt of an alkali metal such as
described prior to the actual distillation.
3. The improvement in the process of obtaining zinc from. zinc ores contain-
ing precious metals, which consists in furnacing the zinc ore in a reducing
atmosphere with carbon, a salt of an alkali metal such as described and lead,
separating the lead now containing the precious metals and then obtaining the
zinc from the slag in any known manner.
WM. P. THOMPSON & Co.,
Patent Agents of Liverpool, Manchester, Birmingham and London.