Improvements in or relating to the Smelting of Mixed Minerals, Ores, and the like, containing Lead and Zinc.
Year: 1897

page_text: Complete Specification Left, 4th Jan., 1898-Accepted, 26th Mar., 1898
PROVISIONAL SPECIFICATION.
Improvements in or relating to the Smelting of Mixed Minerals, Ores,
and the like, containing Lead and Zinc.
I, GEORGE HENRY BLENKINSOP, of Melbourne Place, Swansea, in the County
of Glamorgan, Gentleman, do hereby declare the nature of this invention to be
as follows:
My invention relates to the smelting of mixed minerals, ores, and the like con-
taining lead and zinc in which practically the whole of the zinc is recovered in
the form of metallic zinc with or without a proportion of oxide of zinc by what
is known as the "dry" method.
My process is specially applicable to that class of ores known in commerce as
complex sulphide ores and by means thereof I am enabled to eliminate the zine
from the other metals in an economical and efficient manner under such conditions
as render the process commercially successful.
It has already been proposed to treat mixed sulphides of lead and zinc containing
silver and other metals in various manners by what are known as "wet" pro-
cesses, consisting essentially in the conversion of the zinc into a soluble salt and
lixiviating or washing it out of the material. The residue from this operation
containing the lead, silver and other metals is then treated by one of the well-
known methods.
Another method of treating these complex ores which has been proposed is by
smelting the same with the aid of such fluxes as will cause the ore to melt and
the zinc to become oxidised and dissolve in the slag. Both of these methods are
unsatisfactory on various grounds.
It has also been found that when ores containing zinc and other metals are
smelted by the ordinary method, the zine or a portion of it is reduced to the
metallic state when it reaches the hot zone of the furnace, but that when the
furnace is worked, with a cold top or when the top of the furnace is cooler than
the temperature at which zine condenses, the reduced zinc is either again condensed
and remains in the furnace, or it is oxidised in the furnace and thus interferes
with the fusion of the mineral under treatment, and the recovery of the other
metals. This fact is so well known that persons treating these mixed ores have
first eliminated the zinc by one of the wet methods or they have used fluxes for
the purpose of overcoming this difficulty and in this latter case, the zinc is partly
oxidised at or near the bottom of the furnace or it enters into combination with
the slag in which latter case it has little or no commercial value.
My invention is based upon the property of zinc to become volatile in the
metallic state at a sufficiently high temperature. By means of my invention I am
able to treat large quantities of complex ores or the like containing zinc in the
dry way and to drive off from the same during the operation the zinc either in
the metallic form or in the form of oxide, leaving the gold, silver, lead and other
metals in the form of argentiferous and argentiferous-auriferous metallic lead
and matte.

page_text: In carrying my invention into effect I provide a furnace similar to a blast
furnace or cupola, that is to say a furnace of suitable capacity to which the air
for combustion is supplied under pressure in a heated state and I maintain during
the smelting operation the temperature at the outlet of the said blast furnace
above the temperature at which metallic zinc condenses. The ore or material con-
taining the zine is fed into the blast furnace together with the fuel and with or
without the addition of other materials and the temperature at the outlet is main-
tained above the minimum point aforesaid. In order to maintain the temperature
of the blast at the required point for the carrying out of my process I heat the same
by one of the wellknown methods. I construct in combination with or adjoining
the blast furnace aforesaid a condensing apparatus or cooling chamber or chambers
of suitable construction and capacity into which the gases or products of com-
bustion together with the volatilised zinc pass and in which are deposited the
volatilised metal and any oxide of zinc which has been formed in the process. I
may also combine with the condensing apparatus means for further purifying the
exit gases between the condensing apparatus and the chimney, whereby the said
gases, which contain a high percentage of carbonic oxide may be so purified that
they may be employed for heating the blast to the furnace or for the preliminary
heating or calcining of the materials before they are placed in the blast furnace,
or for other purposes.
By my process a very high percentage of the zinc contained in the ore is
volatilised at the top of the furnace and is recovered as metallic zinc with or with-
out oxide in the condensers aforesaid. The percentage of zinc not volatilised is
not sufficient to interfere with the fusion or smelting of the remaining part of
the mineral treated and the recovery of the other metals. I have found in
practice that the silver and other metals in the ore treated are not volatilised or
carried over with the zinc to any appreciable extent but remain as before stated
with the lead and the matte.
By my process I consequently effect the separation of zinc from large quantities
of complex ore with great economy of time and labour over that requisite in the
processes hitherto in use.
Improvements in or relating to the Smelting of Mixed Minerals, Ores,
and the like, containing Lead and Zinc.
I, GEORGE HENRY BLENKINSOP, of Melbourne Place, Swansea, in the County
of Glamorgan, England, Gentleman, 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:---
My invention relates to the smelting of mixed minerals, ores, and the like con-
taining lead and zinc in which practically the whole of the zinc is recovered in
the form of metallic zinc with or without a proportion of oxide of zinc by what
is known as the "dry" method.
My process is specially applicable to that class of ores known in commerce as
complex sulphide ores and by means thereof I am enabled to eliminate the zine
from the other metals in an economical and efficient manner under such conditions
as render the process commercially successful.
It has already been proposed to treat mixed sulphides of lead and zinc containing

page_text: silver and other metals in various manners by what are known as
wet pro-
cesses, consisting essentially in the conversion of the zinc into a soluble salt and
lixiviating or washing it out of the material. The residue from this operation
containing the lead, silver and other metals is then treated by one of the well-
known methods.
Another method of treating these complex ores which has been proposed is by
smelting the same with the aid of such Huxes as will cause the ore to melt and
the zinc to become oxidised and dissolve in the slag. Both of these methods are
unsatisfactory on various grounds.
It has also been found that when ores containing zinc and other metals are
smelted by the ordinary method, the zinc or a portion of it is reduced to the
metallic state when it reaches the hot zone of the furnace, but that when the
furnace is worked, with a cold top or when the top of the furnace is cooler than
the temperature at which zinc condenses, the reduced zinc is either again condensed
and remains in the furnace, or it is oxidised in the furnace and thus interferes
with the fusion of the mineral under treatment, and the recovery of the other
metals. This fact is so wellknown that persons treating these mixed ores have
first eliminated the zinc by one of the wet methods or they have used fluxes for
the purpose of overcoming this difficulty and in this latter case, the zinc is partly
oxidised at or near the bottom of the furnace or it enters into combination with
the slag, in which latter case it has little or no commercial value.
My invention is based upon the property of zinc to become volatile in the
metallic state at a sufficiently high temperature. By means of my invention I am
able to treat large quantities of complex ores or the like containing zine in the
dry way and to drive off from the same during the operation the zinc either in
the metallic form or in the form of oxide, leaving the gold, silver, lead, and other
metals in the form of argentiferous and argentiferous-auriferous metallic lead
and matte.
In carrying my invention into effect I provide a furnace similar to a 'blast
furnace or cupola, that is to say a furnace of suitable capacity to which the air
for combustion is supplied under pressure in a heated state and I maintain during
the smelting operation the temperature at the outlet of the said blast furnace
above the temperature at which metallic zinc condenses. The ore or material con-
taining the zinc is fed into the blast furnace together with the fuel and with or
without the addition of other materials and the temperature at the outlet is main-
tained above the minimum point aforesaid. In order to maintain the temperature
of the blast at the required point for the carrying out of my process I heat the same
by one of the wellknown methods. I construct in combination with or adjoining
the blast furnace aforesaid a condensing apparatus or cooling chamber or chambers
of suitable construction and capacity into which the gases or products of com-
bustion together with the volatilised zinc pass and in which are deposited the
volatilised metal and any oxide of zinc which has been formed in the process. I
may also combine with the condensing apparatus means for further purifying the
exit gases between the condensing apparatus and the chimney, whereby the said
gases, which contain a high percentage of carbonic oxide may be so purified that
they may be employed for heating the blast to the furnace or for the preliminary
heating or calcining of the materials before they are placed in the blast furnace,
or for other purposes.
By my process a very high percentage of the zinc contained in the ore is
volatilised at the top of the furnace and is recovered as metallic zine with or with-
out oxide in the condensers aforesaid. The percentage of zinc not volatilised is
not sufficient to interfere with the fusion or smelting of the remaining part of
the mineral treated and the recovery of the other metals. have found in
practice that the silver and other metals in the ore treated are not volatilised or
Carried over with the zinc to any appreciable extent, but remain as before stated
with the lead and the matte.
By my process I consequently effect the separation of zinc from large quantities

page_text: of complex ore with great economy of time and labour over that requisite in the
processes hitherto in use.
By way of practical illustration of the manner in which my invention may be
carried into practical effect I give the following example, although the exact
furnace charges will obviously vary considerably according to the composition
and condition of the materials under treatment. Taking the ores known com-
mercially as the "Broken Hill Sulphides" a suitable charge would be:-
1 ton of calcined sulphides
8 cwt. of burnt ore
10 cwt. of slag
suitably mixed together and charged to the furnace in the ordinary manner.
The exit gases from the furnace are most conveniently maintained above the
minimum temperature by the regulation of the hot blast. Should from any cause
the temperature of the blast sink then its pressure may be temporarily increased
until its temperature is restored, and thus the exit heat of the furnace gases
maintained approximately constant.
Upon the regularity of the control of this point the correct working of the
furnace largely depends.
I do not limit myself, however, to these precise details which are given by way
of illustration only, and other means for maintaining the temperature at the exit
might be applied without thereby exceeding the scope of my invention.
"
The term "burnt ore used in the above proportions relates to the well-known
residue from cupreous pyrites, after the bulk of the sulphur has been converted
into sulphurous acid by calcination, and it contains besides oxides of iron and
non-metallic impurities, about 3% copper and a little gold and silver. A portion
of the peroxide of iron present unites with silica to form slag, and another portion
decomposes any blende or zinc sulphide present, and forms sulphide of iron
(matte) liberating zinc in the metallic form.
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. An improved process for separating zinc from non-volatile metals contained
in complex sulphide ores, consisting essentially in smelting the said ores in a
blast furnace by aid of heated air forced through the ore, said heated air being
maintained throughout above the condensation temperature of zinc, substantially
as described.
2. The improved method of smelting complex sulphide ores containing either
lead or zinc, or both metals, consisting essentially in smelting the ore in a blast
furnace in presence of carbon, and with or without the addition of fluxes, by
forcing through the contents of the furnace a current of heated air, the exit
temperature whereof is inaintained above the condensation point of volatilised
metallic zinc, the collection of the volatilised zinc or other metals or oxides in
cooling chambers and the obtaining of the non-volatile metals in the form of matte
and lead alloy.