IMPROVEMENTS IN THE PRODUCTION OF SULPHUR FROM PYRITES, AND IN THE MEANS EMPLOYED THEREFOR
Year: 1878

page_text: LETTERS PATENT to John Hollway, of 7, Jeffrey's Square, in the City of
London, for the Invention of "IMPROVEMENTS IN THE PRODUCTION OF SULPHUR
FROM PYRITES, AND IN THE MEANS EMPLOYED THEREFOR."
Sealed the 2nd August 1878, and dated the 6th February 1878.
PROVISIONAL SPECIFICATION left by the said Jolin Hollway at the Office
of the Commissioners of Patents on the 6th February 1878.
JOHN HOLLWAY, of 7, Jeffrey's Square, of London, "IMPROVEMENTS IN THE PRO-
DUCTION OF SULPHUR FROM PYRITES, AND IN THE MEANS EMPLOYED THEREFOR."
These improvements consist in heating iron pyrites or cupreous iron pyrites by
means of steam, or in a current of steam in closed vessels, in such a manner that I
obtain,―
1st. The whole, or nearly the whole, of one equivalent of the sulphur combined
with iron in the pyrites, as crude sulphur in the uncombined state.
2nd. The other, or nearly the whole of the other equivalent of the sulphur as
sulphuretted hydrogen, which I convert into sulphur or otherwise utilize.
As an example of the mode in which I operate, I fill, or partially fill, with
pyrites a retort chamber or other vessel set in a furnace, and after raising the heat
thereof to dull redness I introduce or drive through the pyrites a current of high
pressure or superheated steam. I then raise the temperature, and I find that the
steam carries over with it in suspension about one equivalent, that is, about one-
half of the sulphur combined with iron in the pyrites in a finely divided condition,
from which state I recover the crude sulphur in a solid form.
Prior to the period at which free sulphur ceases to be given off a stream of
sulphuretted hydrogen is evolved, and continues until the end of the operation.
I then find that the whole, or nearly the whole, of the sulphur bas been obtained
from the pyrites as crude sulphur, or in the state of sulphuretted hydrogen.

page_text: The mode of treating the pyrites may be modified; for example, in lieu of heating
it externally the steam may be introduced at a sufficiently high temperature to
expel the sulphur unaided by external heat..
When treating cupreous iron pyrites containing 47.96 per cent. of sulphur by
the foregoing process I obtained about 23-7 per cent. of crude free sulphur, that is,
practically one-half of the sulphur combined with iron in the pyrites, and nearly
the whole of the remainder of the sulphur was evolved as sulphuretted hydrogen.
When cupreous iron pyrites is thus treated, and when, at the end of the operation
sulphuretted hydrogen almost ceases to be given off, the residue will contain oxide
of iron and sulphide of copper, from which the copper can be afterwards extracted.
When treating pyrites too poor in copper for extraction by the salt process I
distil off, as before described, the greater part of one equivalent of the sulphur
combined with iron in the pyrites. I then expose the residue to the action of air
and moisture, whereby sulphate of copper will be formed, and metallic copper
obtained by any of the well-known means.
The sulphuretted hydrogen produced by my process could be utilized in the
last-mentioned operation, or when required might be employed for other metal-
lurgical purposes.
I further propose to reduce the sulphuretted hydrogen to the condition of
sulphur by either or any of the well-know reactions, for example,―
1st. By means of sulphurous acid.
2nd. By heating the sulphuretted hydrogen in tubes or vessels from which
átmospheric air is excluded.
3rd. By means of persalts of iron.
4th. By means of peroxide of iron.
When availing of the first of the above-mentioned methods I would employ in
preference sulphurous acid mixed with the sulphuretted hydrogen under pressure.
The sulphurous acid required for the foregoing reaction could be conveniently
obtained by burning part of the sulphuretted hydrogen for fuel.
In order to separate arsenic from the crude sulphur the vapours could be passed
through one or more chambers, so as to allow the arsenic to deposit therein before
separating the sulphur from the vapour.
When I require to produce sulphur practically free from arsenic I digest the
product with a dilute solution of alkali or alkaline sulphide, preferably cold.
By these means I render the sulphide of arsenic soluble, so that by decantation
, or filtration it can be removed.

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 6th August
1878.
-
JOHN HOLLWAY, of 7, Jeffrey's Square, London. "IMPROVEMENTS IN THE PRO-
DUCTION OF SULPHUR FROM PYRITES, AND IN THE MEANS EMPLOYED THEREFOR."
These improvements consist in heating iron pyrites or cupreous iron pyrites by
means of steam, or in a current of steam in closed vessels, in such a manner that I
obtain,―
1st. The whole or part of one equivalent of the sulphur originally combined with
iron in the pyrites, as crude free sulphur.
2nd. The other, or part of the other, equivalent of sulphur, either as crude free
sulphur or as sulphuretted hydrogen; and from the latter I obtain sulphur by any
of the well-known processes, or I utilize the sulphuretted hydrogen for precipitating
sulphide of copper from cupreous solutions.
As an example of the mode in which I operate I fill, or partially fill, with pyrites
a retort, chamber, or other vessel set in a furnace, and after heating it to dull
redness I introduce or drive through the pyrites a current of superheated steam.
I then raise the temperature of the vessel, and I find that the steam carries over
in suspension about one equivalent, that is, about one-half of the sulphur originally
combined with the iron in the pyrites. A stream of sulphuretted hydrogen is
evolved, which continues until the end of the operation. I then find that the
whole or part of the sulphur has been obtained from the pyrites as crude sulphur,
and in the state of sulphuretted hydrogen, the relative proportions and the
quantities varying according to the temperature and the length of the operation.
In preference I employ a temperature of about 1,500 degrees Fahrenheit, because
I then obtain a large yield of free crude sulphur, and by still further increasing
the temperature of the operation I obtain the major part of the sulphur originally
combined with the iron in the pyrites, as free crude sulphur, and hydrogen is
evolved, which I burn as fuel or otherwise utilize.
When cupreous iron pyrites is thus treated, and when, at the end of the
operation, hydrogen and sulphuretted hydrogen almost cease to be given off, the
residue consists principally of oxide of iron and sulphide of copper, from which
the copper can be extracted and the oxide of iron afterwards utilized.
By thus treating at a temperature of 1,400 degrees Fahrenheit cupreous iron
pyrites containing 47.96 % of sulphur I obtained about 23.7 % of crude free
sulphur, that is, practically one-half of the sulphur originally combined with the
iron in the pyrites, nearly the whole of the remainder of the sulphur being evolved
as sulphuretted hydrogen.
When pyrites is poor in copper I distil off, as before described, the greater part
of one equivalent of the sulphur. I then either utilize the residue as herein-after
explained, or I expose the said residue to the action of air and moisture, whereby
sulphate of copper will be formed, and from which the metallic copper can be
obtained by any of the well-known means.
The mode of treating the pyrites may be modified; for example, in lieu of heating
the retort, chamber, or other vessel externally, the steam may be introduced at a
sufficiently high temperature to expel the sulphur without the assistance of external
heat; or when sufficient external heat is employed to fuse and keep the sulphides
and oxides molten the superheated steain can be driven through them in somewhat
the same manner that air is driven through molten crude iron in the Bessemer
operation.
I preferably pass the vapours through one or more chambers, so as to allow the
metallic and other substances to deposit therein before separating the sulphur from
the vapours.
When I require to produce sulphur practically free from arsenic I digest the
crude sulphur with a dilute solution of alkali or alkaline sulphide, preferably cold,

page_text: and thus render the sulphide of arsenic soluble, so that by decantation or filtration
it can be removed.
I therefore claim as new and of my Invention, improvements in the production
of sulphur from pyrites, and in the means employed therefor, all as herein-before
substantially set forth.
hand
In witness whereof, I, the said John Hollway, have hereunto set my
and seal, this Second day of August, One thousand eight hundred and
seventy-eight.
Witness,
THOS. WRIGLEY,
75, Chancery Lane.
W.C.
JOHN HOLLWAY. (L.S.)