Improvements in the Treatment of Composite Ores Containing Zinc.
Year: 1891

page_text: Date of Application, 4th Feb., 1891
Complete Specification Left, 16th Oct., 1891-Accepted, 21st Nov., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Composite Ores Containing Zinc.
I, PETER HART, of Gransmoor, Fairfield, Manchester, in the County of
Lancaster, Technical Chemist, do hereby declare the nature of this invention to be
as follows:-
This invention relates to the treatment of mixed or composite ores containing
zine, for the separation of the metallic bases, and is more especially applicable to
poor zinc ores in which the zinc and other metals exist in combination as sulphides
or partly as sulphides and partly as oxides.
In carrying out my invention I first reduce the ores to a comparatively fine
powder which is then mixed in a suitable vessel with sulphuric acid and heated
with frequent stirring to about 300 or 400 degrees Fal. During this operation
large quantities of gas consisting chiefly of sulphurous acid are evolved and these
gases are conducted into an ordinary sulphuric acid chamber where the sulphurous
acid may be converted into sulphuric acid in the usual manner and by the usual
means. The sulphuric acid thus produced may be employed in the treatment of
fresh portions of ore.
When the contents of the vessel have assumed a pasty condition, they are trans-
ferred to a blind furnace and are there occasionally stirred until they have attained
a low red heat when the re-action will be practically completed, and the metals will
for the most part have entered into re-combination as sulphates. A little further
roasting at this temperature, or at a red heat, will render any iron which may be
present insoluble in water.
This point having been reached, the charge may be withdrawn from the furnace
and lixiviated in the ordinary manner, and preferably with hot water. The
lixivium will contain in solution chiefly sulphates of zinc and of copper and the
copper may be removed therefrom by incans of metallic zinc in the usual manner.
Should there be iron in the solution this may also be removed by known means
such for example as by a solution of lime or of an alkaline earth.
If the ore contained lead, this metal will remain in the magma as an insoluble or
nearly insoluble sulphate with the silica and other insoluble matters, and it may be
removed or recovered therefrom by any known and suitable means. For example
the lead may be brought into solution by means of suitable solvents such as a
strong solution of common salt and the lead in this solution may be recovered or
utilised in any convenient manner; or, the metallic lead may be precipitated by
strips of metallic zinc placed in the solution or basic salts of lead may be precipitated
therefrom by the addition of solutions of alkaline salts.
If it is undesirable to attempt the separation of the lead, the magma, with the
addition of a suitable flux or added to other ores, may be smelted in the ordinary
manner.
Dated this 3rd day of February AD 1891
WILLIAM E. HEYS,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in the Treatment of Composite Ores Containing Zinc.
1, PETER HART, of Gransmoor, Fairfield, near Manchester in the County of
Lancaster, Technical Chemist, 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 treatment of mixed or composite ores containing.
zinc, for the separation of the metallic bases, and is more especially applicable to poor
ores in which the zinc and other metals exist in combination as sulphides, or partly
as sulphides and partly as oxides.
In carrying out my invention, I first reduce the ores to a comparatively fine
powder, such for example as will pass through a sieve having about thirty or forty
meshes to the inch. This powder is then mixed in an iron or other suitable and
convenient vessel with sulphuric acid of the strength of 1.750 s.g., in the proportion
of about one part of the powder to about three parts by weight of the acid, and
the mixture is then frequently stirred. The strength and proportion of the acid
may be varied within considerable limits, but it will generally be found that those
given are the more commercially useful. During the process of mixture and
stirring, heat is applied, and when the temperature has risen to about 300 or
400 deg. Fah., gases consisting chiefly of sulphurous acid are copiously evolved.
These gases are preferably conducted into a sulphuric acid chamber, where the
sulphurous acid therein is converted by means of steam and nitric acid or nitrous
gas, into sulphuric acid in the well known manner. The sulphuric acid thúś
produced may be employed in the treatment of further portions of ore.
When the contents of the vessel have assumed a pasty condition, they are pushed
or transferred to a "blind furnace" and are there occasionally stirred until they
have attained a low red heat, when the re-action will be practically completed, and
the metals will, for the most part, have become sulphates. A little further roasting.
at this temperature or at a red heat will render any iron which may be present,
insoluble in water.
This point having been reached, the charge may be withdrawn from the, furnace
and lixiviated in the ordinary manner, and preferably with hot water. The lixivium
will contain in solution chiefly, sulphates of zinc and copper, and the copper maý
be removed in any convenient manner; for example, by inserting scrap zinc or
strips or plates of zinc therein, when the copper will be thrown down as a metallic
precipitate.
Should there be iron in the solution, this may also be removed by known means,
as for example by means of an alkali or an alkaline earth.
If the ore contained lead, this metal will remain in the magma as an insoluble or
nearly insoluble sulphate, together with the silica and other insoluble matters,
and it may be removed or recovered therefrom by any known and suitable means.
For example, the lead may be brought into solution by means of suitable solvents,
such as a strong solution of common salt, and the lead in this solution may be
recovered or utilised in any convenient manner; for example, lead may be precipi-
tated in the metallic form by means of strips or pieces of metallic zinc or by
electrolysis; or oxide of lead may be precipitated therefrom by the addition of
alkalis or alkaline earths.
If it is not desired to attempt the separation of the lead, the magma, with the
addition of a suitable flux, or after being added to other ores, may be smelted in the
ordinary manner.
The lixivium after the herein before described treatment, consists of an almost
pure solution of zinc sulphate, and it may be evaporated to dryness or to crystal-
lisation, so as to fit it to be used in the arts or in commerce or for any purpose for
which it is suitable.

page_text: The whole of the apparatus used in carrying out these improvements is perfectly
well known and in common use and no description of it therefore is necessary.
The apparatus employed in the preliminary stages for example, may differ from the
pot and blind furnace used in the manufacture of sulphate of soda only in respect
of its dimensions, and not necessarily even in this respect.
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 treatment of composite ores containing zinc, substantially as and for the
purpose herein before described.
2. In the process of treating composite ores containing zinc, converting the
metallic bases into sulphates by treating the powdered ore with sulphuric acid and
heat until sulphurous acid is no longer evolved and the mixture has assumed a
pasty form, and by roasting the resulting pasty mass in a blind furnace; substantially
as hereinbefore described.
3. In the process of treating composite ores containing zinc by sulphuric acid,
the utilisation of the sulphurous acid gas given off during the process in the manu-
facture of sulphuric acid for subsequent use in the treatment of further quantities
of the ore, substantially as set forth.
Dated this 5th day of October A.D. 1891.
WILLIAM E. HEYS,
Agent for the Applicant.