IMPROVEMENTS IN AND IN FURNACES USED IN THE METALLURGY OF COPPER
Year: 1881

page_text: "
LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of IMPROVEMENTS
IN AND IN FURNACES USED IN THE METALLURGY OF COPPER." A com-
munication from abroad by Jules Garnier, of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 27th May 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN AND IN FURNACES USED IN THE
METALLURGY OF COPPER." [A communication from abroad by Jules Garnier,
of Paris, France.]
This Invention is based on the fact that reactions in metallurgical furnaces are
influenced by the nature of the lining. For example, in the operations of refining
metals, such as copper, the linings of the furnaces have hitherto been silicious, and
the only matters easily eliminated are those which by oxidation form readily
fusible bases, while those, such as arsenic, antimony, and phosphorus, which form
acids, are not easily climinated.
The Invention consists in a method of eliminating the arsenic, antimony, and
phosphorus from coarse or black copper or matt by refining on a hearth of basic
material, on which at each operation is spread a layer of basic fluxes and carbonates,
such as lime or magnesia, raw limestones or dolomites, peroxide of manganese, litharge,
fluor spar, &c.
The proportion of basic fluxes is sufficient to thoroughly saturate the acidifiable
impurities of the matt or coarse copper, while the carbonic acid disengaged from
the carbonates stirs up, and more or less oxidizes the charge.
The copper and matts are melted under an oxidising action, the fire is then
urged, the slagg skimmed off, the oxidation recommenced, and skimming repeated
until the acidifiable impurities are almost entirely eliminated.
The iron contained in the coarse copper or matt is oxidized and partly removed
with the slag, but the whole of the iron cannot be economically removed in this

page_text: way. It is therefore necessary to do this at a separate operation upon a silicious
hearth, either before or after the elimination of the acidifiable impurities. It is
generally preferable to refine the copper on a silicious hearth until it contains not
more than about one half per cent. of iron, and then to refine it on a basic hearth
as above mentioned, so as to eliminate the remainder of the iron or sulphur it
contains, and particularly the arsenic, antimony, or phosphorus. The operation
may be much
more rapidly effected by employing for the basic furnace a
regenerative furnace, and a revolving hearth which brings all the molecules of the
bath well into contact with the basic lining.
The hearth is made of lime or calcined dolomite agglomerated with clay in such
proportions as to be fritted by the action of the fire. The sides of the furnace are
rammed with this material, and then surmounted by a thin parting course of lime
or pure magnesia or alumina, which neither melts with the silica of the bricks of
the arch, nor with the basic material of the walls; the arch is then completed in
the ordinary way with silica bricks.
The hearth, properly so called, is fritted in thin layers at the same time as the
basic mixture of the walls.
If the hearth is rotary, I line the sides with basic bricks, and make the hearth as
above described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
26th November 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN AND IN FURNACES USED IN THE
METALLURGY OF COPPER." A communication from abroad by Jules Garnier, of
Paris, France.
This Invention is based on the fact that reactions in metallurgical furnaces are
influenced by the nature of the lining. For example, in the operations of refining
metals, such as copper, the linings of the furnaces have hitherto been silicious, and
the only matters easily eliminated are those which by oxidation form readily fusible
bases, while those, such as arsenic, antimony, and phosphorus, which form acids, are
not easily eliminated. Having regard to these facts, a reverberatory furnace for
refining copper was, by way of experiment, made with a hearth of fritted lime,
upon which was placed a layer of raw limestone and lime covered with peroxide of
manganese. The furnace was then charged with arsenical copper containing a
little sulphur and iron, as obtained from Rio Tinto, and the arsenical copper melted
by an oxidising current of air. The fire was then urged, and the scorin on being
skimmed off was found to already contain a very large proportion of arsenic, the
quantity of which in the copper was reduced by this one operation from 1.12%
to 0.360%. The copper was then again oxidised, and a little lime added as a base,
and after resmelting and urging the fire, the quantity of arsenic contained was still
further reduced to 0143%. By this time also the whole of the iron and sulphur
had disappeared. As however a regenerative furnace was not employed the
arsenious scoria were not sufficiently acid to be readily fusible, they adhered to the
sides, and on "poling" a portion of the arseniate formed was reduced and became
again mixed with the metal. The copper when introduced into the furnace
contained 0.320% of iron, whereas at the close of the operation it contained
but 0.030°/
This Invention, which is based on the foregoing and other experiments that it is
unnecessary to here describe, consists,-
1st. In a method of eliminating the arsenic, antimony, and phosphorus from
crude copper or matt by refining on a hearth of basic material, on which at each
operation is spread a layer of basic and oxidising matters, such as lime or magnesia,
raw limestones, or dolomites, with peroxide of manganese, litharge, fluor spar, &c.
The proportion of basic fluxes should be sufficient to thoroughly saturate the
acidifiable impurities of the matt or crude copper, while the carbonic acid
disengaged from the carbonates stirs up and more or less oxidises the charge. The
copper and matts are treated in the manner above described, that is to say, they
are inelted under an oxidising blast, the fire is then urged, the slag skimmed off,
the oxidation recommenced, and skimming repeated until the acidifiable impurities
are almost entirely eliminated.
The iron contained in the crude copper or matt is oxidised and partly removed
with the slag, but the whole of the iron cannot be economically removed in this
way, and it is therefore necessary to eliminate it at a separate operation upon a
silicious hearth either before or after the elimination of the acidifiable impurities.
It is generally preferable to refine the copper on a silicious hearth until it contains
not more than about one half per cent. of iron, and then to refine it on a basic
hearth as above mentioned, so as to eliminate the remainder of the iron and
sulphur it contains and particularly the arsenic, antimony, or phosphorus.
The operation may be much more rapidly effected if for the basic furnace the

page_text: high temperature of a regenerative furnace be available and a revolving hearth be
employed which brings all the molecules of the metal well into contact with the
basic lining.
The stationary hearth is made of lime or calcined dolomite agglomerated with
clay in such proportions as to be fritted by the heat. The sides of the furnace are
rammed with this material and then surmounted by a thin parting course of lime
or pure magnesia, or even of, alumina, which neither melts with the silica of the
bricks of the arch, nor with the basic material of the walls; the arch is then built
with silica bricks in the ordinary way.
The hearth, properly so called, is fritted in thin layers at the same time as the
basic mixture of the walls. If the hearth is rotary I line its sides with basic
bricks, and make the hearth within this boundary as above described.
Having described the nature of the said Invention, and the manner of
performing the same, I declare that what I claim as the Invention to be protected
by the herein before in part recited Letters Patent is,-
The employment of a fixed or rotary hearth (particularly a rotary one) of basic
material, whose action is combined with that of basic and oxidising matters added
at each operation, such as natural, raw, or calcined carbonates, with peroxides of
manganese, &c., from which carbonates carbonic acid becomes disengaged both
during and after the fusion of the copper, and acts as a mixing and oxidizing agent
in the metal.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Twenty sixth day of November, A.D. 1881.