An Improved Method of Extracting Copper from Ores or Compounds containing the same.
Year: 1890

page_text: Date of Application, 21st Nov., 1890
Complete Specification Left. 21st Aug., 1891-Accepted, 21st Nov., 1891
PROVISIONAL SPECIFICATION.
An Improved Method of Extracting Copper from Ores or Compounds
containing the same.
We, THOMAS DAVIES NICHOLLS, of Swansea, South Wales, Assistant
Manager of The Cape Copper Company's Works at Briton Ferry, CHRISTOPHER
JAMES, of Ida Villa, Swansea, Metallurgist, and THE CAPE COPPER COMPANY,
LIMITED, of 9, Queen Street Place, Upper Thames Street, in the City of London,
do hereby declare the nature of this invention to be as follows :-
This invention relates to the extraction of copper from ore and other compounds
containing the same, and consists in an improved process or method of treatment,
whereby a good quality. of copper is obtained at a reduced cost and in less time
than by the process commonly employed.
In the treatment of copper ore for the production of copper according to our
improved method, we proceed in the ordinary manner until a regulas or like product,
containing from 65 to 80 per cent. of copper (and such a quantity of iron as it may
be deemed expedient to retain for the proper
E slagging off" of the non-volatile
impurities), is obtained. This regulus or product having been crushed, is calcined
until as much sulphur as is desirable has been driven off. The calcined regulus or
product is then mixed with a suitable proportion of crushed but uncalcined regulus
such as previously referred to or with other regulus or product of a like description;
the quantities of the calcined and uncalcined regulus or product being in such ratio
that the oxygen contained in the calcined portion will combine with all the sulphur
contained in the uncalcined portion. A charge of this mixture (with the addition
of sand or other suitable flux) is then placed in a refinery furnace and melted. The
volatile impurities, whether left in the calcined portion of the charge or present in
the uncalcined part, are volatilised by the intense chemical heat generated and are
carried away with the copious discharge of sulphurous gas which ensues. The
copper is finally skimmed, brought to pitch and laded or run into ingots or cakes as
desired.
By the employment of our improved process, a good quality of copper is
produced, in the refinery furnace and at a single operation, by the action of
calcined regulus, or like calcined product, upon uncalcined or raw regulus, or like
uncalcined product; thus avoiding the expense and waste incidental to the
customary process in which the regulus is roasted.
Dated this 21st day of November 1890.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Agent for the Applicants.
COMPLETE SPECIFICATION.
An Improved Method of Extracting Copper from Ores or Compounds
containing the same.
We, THOMAS DAVIES NICHOLLS, of Swansea, South Wales, Assistant
Manager of The Cape Copper Company Works, at Briton Ferry, CHRISTOPHER
JAMES, of Ida Villa, Swansea, Metallurgist, and THE CAPE COPPER COMPANY of
9 Queen Street Place, Upper Thames Street in the City of London, do hereby
declare the nature of this invention to be as follows:-
-
This invention relates to an improved method of producing fine copper from
copper compounds known as "matte," "regulus," or from precipitate or ores,

page_text: whereby a good quality of refined copper is obtained at a reduced cost, and in less
time than by the process commonly employed.
"
In the ordinary methods now in use after the copper is concentrated into a matte
or regulus, of about seventy five per cent. of copper, this matte, consisting
principally of copper and sulphur is piled in as large pieces as practicable in a
roaster furnace, and slowly sweated down, whilst exposed to a current of air, let in
through the side door of the furnace, through air holes or "plugs" provided for
that purpose, or through passages arranged through the fire by the workman ;-
then burning off in successive stages nearly all the sulphur, and leaving the copper,
after melting and skimming, to be tapped out as "blister 65
or pimple" copper.
This operation seldom takes less than twenty four hours for the production of three
tons of pimple or blister copper, from matte of from seventy five or seventy
six per rent. of copper-while a large amount of copper passes into the roaster slags,
which have to be re-smelted for the recovery of that copper. The pimple or
blister copper, thus made, is then filled as pigs" into a refinery furnace and again
sweated down under an oxidising flame, skimmed, refined, and brought to the
required pitch for lading into cake, ingots, annodes, &c.
r
In the new method proposed herein, we avoid the expensive and wasteful
operation of roasting in a roaster furnace (producing a heavy slag in such operation)
by substituting a calcination of a portion only of our matte-then mixing this
calcined portion with a suitable proportion of raw (uncalcined matte) this mixture is
then charged directly into a refinery furnace, and melted at once, refined in the
usual way, and laded into ingot, anodes, &c. as may be required.
We find in practice that the best and most economical matte for our process is
one of about seventy six to seventy eight per cent. of copper, matte of this pitch
containing but little iron, and so making very little slag in the refinery furnace.
The whole of this matte is crushed through a 3/8" screen (or smaller if convenient,
though when rich matte is treated, fine dust is wasteful) and a portion of this matte
we calcine in a reverberatory calciner or revolving cylinder calciner, or any calciner
or kiln at present in ordinary use, or that may be designed or constructed by the
above named inventions or others. The calcination of the matte is so conducted
until all the sulphour has been extracted, and it is technically known as "dead,”
or nearly so, and is afterwards mixed with such a proportion of raw matte as will
suffice. When both portions are melted together, to render all the copper in the
refinery charge metallic copper of a pitch similar to the blister copper from the
ordinary roasting process.
The reactions which ensure the success of this method of working may be
described as follows.―
Copper matte of the preferred pitch consists essentially of copper and sulphur
(copper sulphide) CuS-this, when calcined perfectly, would be changed to copper
oxide, (Cu) of equal weight with the copper sulphide operated on this copper
oxide (CO) upon being melted with its own weight of raw (uncalcined)
copper sulphide, would reduce all the copper from both portions, with the evolution
of all the oxygen and sulphur present as sulphur gas, as expressed by the well
known formula:-
다.
Cu₂S + 2 CuO = 4 Cu + SO,
Laan naufant anlaination maduning the und avid
taking about double the weight of calcined matte to reduce the raw sulphide. In
case of a mixture of the two oxides being produced in the calcination, the quantity
of sulphide (raw matte) required for the reduction to copper of the whole of the
mixed oxides will be proportionate to the quantity of each oxide present in the
charge, but in all cases we use sulphur as the reducing agent in our charge for
copper, whether such sulphur be added as sulphur, or as a sulphide of copper or
other metal,

page_text: In practice we find that to perfectly calcine the portion of matte so treated is
expensive and tedious,-the calcination of the copper sulphide to red oxide (Cu₂O)
being comparatively easy whilst the further calcination of this red oxide to black
oxide (CuO) requires so much longer time and greater heat, that, although the
black oxide will carry its own weight of raw matte in the refinery charge, it is
cheaper to calcine our charge until upon trial it is found that about two parts of
calcined matte and one part of raw matte will upon melting together render all the
copper as blister copper with very little slag.
We claim that by treating only about two thirds of our matte in a calciner to a
more or less perfect state of calcination, and then mixing with it about one third
of raw matte, and then melting the total quantity in a refinery furnace, with the
immediate production of metallic copper, which is at once refined whilst still
melted; or alternatively by first bricking our charge of mixed raw and calcined
matter with or without fluxes, and by melting in a cupola or blast furnace, by
running the resulting copper at once into bars ingots anodes &c. or into a refinery
furnace to be brought to pitch and loaded into cake, ingots, anodes &c.,-that good
copper is produced at far less cost, and by a more direct and natural method than
by the usual roasting and refinery processes,-that more copper is produced in a
saleable form, that far less copper is returned in slags to be reworked, than is at
present done by first roasting and melting in a roaster and again in a refinery
furnace, from which a heavy proportion of copper is returned in slags from each
operation, and that in our process the locking up of large quantities of copper in
roaster furnace bottoms is entirely avoided.
In our method of working we find that all volatile impurities (antimony, arsenic,
bismuth, &c.) are more freely got rid of than in the ordinary roasting process,
partly in the thorough calcination of the calcined portion, and again during the
evolution of the large volumes of sulphur gas given off on melting the mixed
charge in the refinery, aided by the intense chemical heat developed by the reaction
set up by the combining of the melting oxide and sulphide.
The non-volatile impurities (iron nickel &c.) are got rid of, to a greater extent
than by the roasting process, by a judicious mixing of the proportions of calcined
and uncalcined portions of the charge, so as to obtain a slag of melted oxides with
added fluxes. Such nonvolatile impurities are naturally collected in this slag,
and are skimmed off with it, suitable fluxes being added when very impure matte is
treated.
We may use natural or artificial oxides or precipitates instead of calcining a
portion of matte, when such oxides are sufficiently free from gangue as to render
their use economical.
Although matte of from seventy six to seventy eight per cent. of copper is
preferred, correspondingly good results are obtained from poorer mattes, matte
of even thirty per cent. of copper giving a good return although made from very
impure materials.
The actual cost of practically working the method has been found to be in all
cases much less than half the cost of the ordinary method as carried out in well
conducted works using the roasting process.
It is thus shewn that the principle upon which our process is based is the
reduction of an oxide by a sulphide and this principle we apply in the following
manner.
First. By calcining a portion of matte till all the copper is in the state of black
oxide-when we mix it with an equal weight of uncalcined matte viz.
1 ton copper sulphide about 80% copper
and about 20% sulphur
1 ton copper (black) oxide about 80%
copper and about 20% oxigen
Melted together in the refinery
produce about 32 cwts. copper
and about 8 cwts. sulphurous
anhydride

page_text: Second. By calcining a portion of matte until the copper is in the state of red
oxide, when we melt this with about half its weight of uncalcined matte, viz. :—
1 ton red copper oxide about 89% copper
and about 11% oxygen
ton copper sulphide about 80% copper
and about 20% oxygen
as expressed by Cu₂S + 2 Cu,O=6 Cu + SO₂
Melted together in the refinery
produce about 25 cwts. copper
and about 4 cwts. sulphurous
anhydride
Third. By so cafeining a portion of matte as to produce a mixture of the two
oxides named above and mixing them with the necessary proportion of raw matte.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1st. A method or process for the more direct production of refined copper from
copper matte or regulus (avoiding the usual lengthy and expensive roasting process)
consisting of the mixture and treatment of the raw matte with highly calcined
matte in equal weights, or with less calcined matte in the proportion of 2 by weight
of calcined to one of raw matte, in a reducing furnace, so that the oxygen and
sulphur situated in the two parts of the "matte" respectively may combine to
produce SO, and increase of heat, and leaving, when accurately proportioned almost
all the copper reduced to refined metal, after the passing away of the sulphur and
other volatile gases substantially as described.
2nd. In such a process for the production of refined copper by the mutual
reaction of sulphur and oxygen in the charge, the substitution of natural or artificial
oxides or precipitate of copper, to react with the raw matte, in a refinery furnace,
to produce the reduction of the copper by proper proportions of the oxide and
sulphide charges, to the condition of refined copper substantially as described.
Dated this 21st day of August 1891
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicants.