IMPROVEMENTS IN THE PRODUCTION OF SULPHUR FROM PYRITES, AND THE SEPARATION OF METALLIFEROUS SUBSTANCES THEREFROM AND THEREBY, AND IN THE MEANS EMPLOYED THEREFOR." PROVISIONAL SPECIFICATION
Year: 1878

page_text: LETTERS PATENT to John Hollway, of 7, Jeffrey's Square, London, for the
Invention of "IMPROVEMENTS IN THE PRODUCTION OF SULPHUR FROM PYRITES,
AND THE SEPARATION OF METALLIFEROUS SUBSTANCES THEREFROM AND
THEREBY, AND IN THE MEANS EMPLOYED THEREFOR."
PROVISIONAL SPECIFICATION left by the said John Hollway at the Office
of the Commissioners of Patents on the 21st March 1878.
JOHN HOLLWAY, of 7, Jeffrey's Square, London. "IMPROVEMENTS IN THE PRO-
DUCTION OF SULPHUR FROM PYRITES, AND THE SEPARATION OF METALLIFEROUS
SUBSTANCES THEREFROM AND THEREBY, AND IN THE MEANS EMPLOYED THEREFOR."
These improvements consist in treating iron pyrites or cupreous iron pyrites with
or without the addition of other metalliferous substances or slag, producing
materials in such a manner that I utilize the sulphides as fuel, and obtain,―
1st. Nearly the whole of the sulphur from the pyrites as crude free sulphur and
sulphurous acid, and in certain cases sulphuretted hydrogen.
2nd. In separate groups, the metals originally contained in the pyrites or other
substances operated on in the metallic state, or in the form of sulphides or
oxides.
3rd. A slag rich in iron from which metallic iron can be obtained.
In carrying out my object I employ a furnace, which might be a modification of
the Bessemer converter or of the ordinary blast furnace, so closed at the top as to
prevent the escape of the free sulphur, sulphurous acid, and the metallic substances
carried over by the vapours.
I drive in air at or near the bottom of the furnace, and by increasing or decreasing
the quantity I regulate the temperature of the operations.
The operation may be commenced by running a quantity of molten sulphide and
slag into the furnace, and then introducing the pyrites with or without other
metalliferous substances and slag-producing materials at the top of the furnace;
they descend, and part of the sulphur combined with the iron in the pyrites is
driven off as free sulphur, and the resulting sulphides are burnt by the oxygen of

page_text: the air driven in at the lower part of the furnace with the formation of oxide of
iron and sulphurous acid.
While the pyrites is being introduced care must be taken to prevent access of a
greater volume of air than is necessary for the combustion of the sulphur and
oxidation of the sulphide of iron contained in the lower part of the furnace.
One of my objects in thus operating is to avoid the combustion of the sulphur
in the pyrites introduced at the upper part of the furnace, and to carry over in the
stream of sulphurous acid and nitrogen gases as much as possible of one equivalent
of the sulphur in the free state, which is liberated by the heat evolved by the
oxidation of the iron and sulphur in the production of sulphurous acid, as before
inentioned.
Proper arrangements have to be made for collecting and separating the
sulphur, sulphurous acid, and the metallic substances carried over by the
vapours.
When employing pyrites containing very little silica I find it advisable to add
silicious and other slag-producing materials, in order to form with the oxide of iron
produced a liquid slag fusible at a low temperature, and of such a gravity that
the resulting sulphides being heavier will sink through, and collect below the
Blag.
When adding slag-producing materials I utilize those which contain valuable
metals in such small quantities as render them unsuitable for treatment by ordinary
methods.
When treating by this method substances containing valuable metals I preferably
draw off first the superincumbent slag, thus avoiding their loss in the slag; and for
the same reason I afterwards render basic the resulting slag by the introduction of
alkalies or alkaline earths.
I also withdraw from time to time the slag when the quantity becomes excessive,
and so saturated with oxide of iron that it does not readily take up the oxide of
iron formed by the oxidation of sulphide of iron.
When sulphide of lead is present it is oxidized first, and the resulting oxide by
contact with the sulphides is converted into metallic lead, which, being heavier,
collects below the sulphides.
The sulphide of iron is next oxidized, and is then taken up by the superincum-
bent molten slag. Thus sulphide of copper is always accumulating, and can be
withdrawn when sufficiently rich in copper.
When I have discontinued introducing pyrites I drive in the air very rapidly, in
order to raise the temperature and expedite the operations, and I continue to
blow in air until the sulphide of iron has been sufficiently removed by
oxidation.
When employing a modification of the Bessemer converter, the high temperature
I attain not only permits me to stop blowing in air so as to allow the sulphides to
separate from the slag, but also affords the necessary time for withdrawing the
sulphides of copper, iron, and other metals; also the metallic lead containing the
silver and gold.
When, however, employing a fixed furnace, such as a modification of the ordinary
blast furnace, it may be necessary to draw off simultaneously the cupriferous sul-
phides with some of the slag rich in iron, and allow their separation to take place
outside the furnace.
In such case the sulphide and slag should be withdrawn at a sufficiently high
temperature to enable them to separate before cooling.
.
When these cupriferous sulphides have been withdrawn I recommence_intro-
ducing pyrites, and the heat of the slag expels part of the sulphur combined with
iron in the pyrites as free sulphur; and I utilize as before the resulting sulphides
as fuel, and obtain,―
1st. Nearly the whole of one equivalent of the sulphur combined with iron in
the pyrites as crude sulphur in the free state.
2nd. Nearly the whole of the remainder of the sulphur as sulphurous acid.

page_text: 3rd. The metals or metallic substances carried over by the vapours, for example,
oxides of lead, zinc, and antimony.
4th. The sulphides of copper, iron, and other metals.
5th. The metallic lead, if existing in sufficient quantity, and with it the silver and
gold present.
6th. A slag rich in iron, from which metallic iron can be obtained.
It is well known that when pyrites is heated it gives off part of its sulphur,
which can be collected; but in practice it has been found difficult, except with
great wear and tear of plant, to obtain much more than one-fourth of sulphur from
pyrites when heated externally in closed vessels, as in attempting to expel a further
proportion of the sulphur the residue melts, and the tubes or retorts require to be
constantly renewed.
When, however, by my process pyrites is heated, and Bessemerised with atmo-
spheric air, an unlimited quantity of pyrites can be melted without using any
external heat, the necessary heat being obtained from the oxidation of the sulphur
and the iron, which not only is sufficient for melting the pyrites, but there is a
surplus which can be utilized for treating other substances, so as to obtain in
different groups as metals, or in the form of sulphides or oxides, the metals
originally contained in the pyrites and other substances introduced into the
furnace.
A very high temperature is obtained in a similar way in the Bessemer converter,
where molten crude iron is oxidized by ordinary air, the temperature of the metal
being raised by the oxidation of the silicon and carbon present.
In order to obtain a large proportion of the sulphur in the free state the modified
Bessemer or blast furnace must be of sufficient depth or height, so that the free
oxygen of the air blown in does not come into contact with the pyrites, but is
all expended in the formation of oxide of iron and sulphurous acid, as before
described.
I also find, for the same reason, that it is advisable to introduce the pyrites in
small pieces, and to have sufficient liquid slag through which the pyrites passes
before mixing with the sulphide at the lower part of the furnace.
Thus, both the sulphurous acid and nitrogen of the air assist the distillation of
the sulphur by carrying with them the sulphur liberated by the heat produced in
the oxidation of the iron, and in the formation of the sulphurous acid; and also
carry over the metals and metallic substances volatilized.
When I desire to obtain a larger proportion of freo sulphur, in lieu of employing
the surplus heat for treating other metalliferous substances, I burn and oxidize the
sulphides in the lower part of the furnace by means of air driven in at or near the
bottom; and I drive in superheated steam at a sufficiently higher level. I introduce
the air in sufficient quantity to compensate for the reduction of temperature caused
by the steam employed, and also to produce enough heat to distil off the sulphur
from the pyrites introduced at the upper part of the furnace.
By driving in steam, sulphuretted hydrogen is formed, which re-acts on part of
the sulphurous acid generated by the combustion of sulphur at the lower part of
the furnace.
The sulphurous acid and nitrogen gases carry over with them the free sulphur
resulting from these operations. In this way I not only obtain the free sulphur
liberated from the pyrites, but also a further proportion of free sulphur formed by
the mutual decomposition of the sulphuretted bydrogen and sulphurous acid; and,
to facilitate this re-action the escaping gases can be passed into water.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Hollway in the Great Seal Patent Office on the 21st September
1878.
"IMPROVEMENTS IN THE
JOHN HOLLWAY, of 8, Jeffrey's Square, London.
PRODUCTION OF SULPHUR FROM PYRITES, AND THE SEPARATION OF METALLIFEROUS
SUBSTANCES THEREFROM AND THEREBY, AND IN THE MEANS EMPLOYED THEREFOR.”
These improvements consist in treating iron pyrites, cupreous iron pyrites, and
pyrites' residues with or without the addition of other metalliferous substances or
slag-producing materials, in such a manner that I utilize the sulphides as fuel, and
obtain,―
1st. Nearly the whole of the sulphur from the pyrites as crude free sulphur, and
as sulphurous acid.
2nd. In separate groups the metals originally contained in the pyrites and other
substances operated on, either in the form of sulphides, oxides, or in the metallic
state.
3rd. A slag rich in iron, from which metallic iron can be obtained.
In carrying out this object I employ either a fixed furnace, such as a modification
of the ordinary blast furnace and the Bessemer converter or a modified Bessemer ;
but, in preference, I employ both descriptions of furnace, so arranged that the free
sulphur, sulphurous acid, and the metallic and other substances carried over by the
vapours are collected. This can be effected by somewhat similar means to those
employed for collecting and utilizing the gases from blast furnaces.
I drive in air at or near the bottom of the furnaces, and I regulate the temperature
of the operations by increasing or decreasing the quantity.
Sulphide of iron being oxidized in preference to sulphide of copper the latter
always accumulatos, and I withdraw the regulus whenever sufficiently rich in
copper.
When commencing the operation it is convenient to run into the fixed furnace a
quantity of molten sulphide of iron, and then introduce at or near the top of the
furnace the pyrites or sulphides with or without other metalliferous substances and
slag-producing materials; they descend, and the heat evolved from the oxidation of
the sulphides in the lower part of the furnace causes part of the sulphur originally
combined with the iron in the pyrites to be driven off as free sulphur, and the
resulting sulphides are subsequently burnt by the oxygen of the air driven in at
the lower part of the furnace, thereby producing the heat necessary for continuing
the operations.
When employing pyrites or residues therefrom containing very little silica it is
advisable to add silicious and other slag-producing materials, in order to form with
the oxide of iron produced an easily fusible liquid slag of such a gravity that the
resulting regulus being heavier will, when no longer agitated, sink through and
collect below the molten slag.
I employ, in preference, metalliferous substances which will supply the necessary
slag-producing materials; and I am thus enabled to utilize substances which contain
valuable metals in such small quantities as to render them unsuitable for treatment
by ordinary methods.
I withdraw from time to time the slag when the quantity becomes excessive, and
so saturated with oxide of iron that it does not readily take up that formed by the
oxidation of the sulphide of iron.
Before introducing valuable metalliferous substances into the furnace I withdraw
the slag, or render it so basic by means of fluxes that the loss of the valuable
metallic oxides is reduced to a minimum.
When 1 employ a fixed furnace, and continously drive air through the sulphides
contained therein, I find that the regulus withdrawn therefrom is mixed with slag;
I therefore either withdraw the regulus and slag at a temperature sufficiently high
to permit them to separate before cooling, or I run them into another furnace,

page_text: where I maintain them fluid by extraneous heat, or into a modified Bessemer, in
either of which I continue the oxidation by means of air.
After withdrawing the regulus I recommence introducing pyrites, and the
slag left in the furnace being very hot expels as free sulphur part of the sulphur
originally combined with the iron in the pyrites.
With an ordinary Bessemer plant, and employing pyrites containing 31, per cent.
of copper, I have obtained in actual experiments a regulus containing as much as
59-98 per cent. of copper, and 48 ozs., 6 dwts., 3 grs., of silver, and 1 oz., 6 dwts.,
3 grs., of gold per ton of regulus with a slag containing less than one-tenth per cent.
of copper.
When thus operating the heat produced by the oxidation of the sulphides in the
lower part of the furnace is sufficient, not only to expel as free crude sulphur part
of the sulphur combined with the iron in the pyrites, but there is a surplus of heat,
which I utilize for treating other metalliferous substances; and I thus obtain in
different groups as inetals, or in the form of sulphides, oxides, or as slag, the metals
originally contained in the pyrites, and in the other substances introduced into the
furnace.
I employ a hot blast of air when I desire to operate on a large proportion of
metallic oxides as compared with the pyrites and sulphides employed; and when I
desire to obtain a large proportion of free sulphur, in lieu of employing all the
surplus heat for treating metallic oxides, I introduce superheated steam into the
furnace, in addition to the air, which latter I introduce as a hot blast, and in
sufficient quantity to compensate for the reduction of temperature caused by the
steam employed; and also to produce enough heat to expel as free sulphur about
one equivalent, that is, about one-half of the sulphur originally combined with
the iron in the pyrites introduced at the upper part of the furnace.
By thus employing superheated steam I obtain free sulphur expelled from the
pyrites, whereby proto-sulphide of iron is formed, and an additional quantity of
sulphur liberated from the residual sulphides.
While pyrites is being introduced care must be taken to prevent access of a
greater volume of air than is necessary for the formation of sulphurous acid and
oxide of iron by the combustion of the sulphide of iron contained in the lower part
of the furnace; and, in preference, I employ furnaces of sufficient depth or height,
so that the free oxygen of the air blown in neither comes in contact with the
pyrites nor with the sulphur liberater, but is expended in the formation of oxide of
iron and sulphurous acid, as before described. For the same reason it is desirable
to introduce the pyrites in small pieces; and I thus utilize the small pyrites which
has been hitherto wasted.
The high temperature at which the gases pass upward in the furnace assists the
liberation of the sulphur, and the gases carry with them the free crude sulphur, as
well as the metals and other substances volatilized.
By these means I utilize the sulphides as fuel, and obtain,―
1st. Free sulphur expelled from the pyrites, whereby proto-sulphide of iron is
formed, and also a further proportion of sulphur, which is liberated when super-
heated steam is employed.
2nd. Nearly the whole of the remainder of the sulphur as sulphurous acid.
3rd. The metals and other substances carried over by the vapours.
4th. The cupriferous sulphides which contain the silver and gold originally in the
pyrites, and other substances employed.
5th. A slag rich in iron, from which inetallic iron can be obtained.
When necessary I line the furnaces and the retorts, chambers, and other vessels,
as well as the passages through which the gasses pass, with materials which will
protect them from the action of the sulphides or oxides present; and I mako
arrangements for collecting and separating the sulphur, sulphurous acid, and the
substances carried over by the vapours.
I preferably pass the vapours through one or more chambers, so as to allow the

page_text: metalliferous substances to deposit therein before separating the sulphur from the
vapours.
I therefore claim as new and of my Invention, improvements in the production
of sulphur from pyrites, the utilization of sulphides in lieu of fuel, the obtaining in
separate groups as metals, or in the form of oxides, sulphides, or as slag the metals
originally contained in the pyrites and other substances operated on, and in the
means employed therefor, all as herein-before substantially as set forth.
In witness whereof, I, the said John Hollway, have hereunto set my hand
and scal, this Twentieth day of September, in the year of our Lord One
thousand eight hundred and seventy-eight.
Witness,
W. E. LANCE,
J. T. SNOW,
Clerks to Hollway Brothers,
Jeffrey's Square,
London.
JOHN HOLLWAY. (L.S.)