IMPROVEMENTS IN PURIFYING OR REFINING COPPER
Year: 1878

page_text: LETTERS PATENT to John Wilkes, of Birmingham, in the County of War-
wick, Manufacturer, and Thomas Johnson, of Birmingham aforesaid, Copper
Refiner, for the Invention of "IMPROVEMENTS IN PURIFYING OR REFINING
COPPER"
Sealed the 7th February 1879, and dated the 21st August 1878.
PROVISIONAL SPECIFICATION left by the said John Wilkes and Thomas
Johnson at the Office of the Commissioners of Patents on the 21st August
1878.
JOHN WILKES, of Birmingham, in the County of Warwick, Manufacturer, and
THOMAS JOHNSON, of Birmingham aforesaid, Copper Refiner. "IMPROVEMENTS IN
PURIFYING OR REFINING COPPER."
In several kinds of the crude copper supplied to commerce, and especially in the
kind known as Chili bars, arsenic, and antimony, and tin are present to an injurious
extent, and the ordinary. methods of purifying or refining copper only remove
these impurities imperfectly.
Our Invention consists of the improvements herein-after described in purifying
or refining copper, whereby the said impurities are so effectually removed that
from Chili bars and other impure kinds of copper we produce copper of a quality
equal to that known as best selected copper.
Our said improvements consist in treating the impure copper in a state of fusion
with a mixture of calcic hydrate (otherwise called slaked lime) and copper scale,
or oxide of copper, or with a mixture of calcic hydrate and haematite or peroxide
of iron, or with a mixture of calcic hydrate and peroxide of manganese.
The relative proportions of these materials which we have found to answer well
in practice are as follows:-
One part by weight of copper to three parts by weight of calcic.hydrate.
One part by weight of peroxide of iron to two parts by weight of calcic hydrate.

page_text: One part by weight of peroxide of manganese to two parts by weight of calcic
hydrate.
Three parts of either of the above-described mixtures is thrown into the refining
furnace containing a charge of seven or eight tons of the copper to be purified, and
well mixed with the copper by a process of rabbling. The furnace is then closed,
and the temperature raised until the slag formed is fit to be skimmed off. This
process is repeated until by trial samples the whole of the arsenic, antimony, and
tin is found to have been removed.
The slags containing the arsenic, antimony, and tin are either smelted with a
reducing agent, and the copper obtained cast into cakes, or the said slags are smelted
with regulus or a sulphide ore, the proportion of slag and regulus being so adjusted
that the product formed shall contain about fifty per cent. of copper.
After the slag has been carefully skimmed off there is then added to the regulus
a mixture of one part of oxide of copper and two parts of caustic soda ash, which
oxidizes the arsenic, antimony, and tin, forming arseniate, antimoniate, and stannate
of soda, which is skimmed off and thrown into a tank containing water, which
dissolves out the above salts, namely, arseniate, antimoniate, and stannate of
soda.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Wilkes and Thomas Johnson in the Great Seal Patent Office
on the 15th February 1879.
JOHN WILKES, of Birmingham, in the County of Warwick, Manufacturer, and
THOMAS JOHNSON, of Birmingham aforesaid, Copper Refiner.
"IMPROVEMENTS IN
PURIFYING OR REFINING COPPER."
In several kinds of the crude copper supplied to commerce, and especially in the
kind known as Chili bars, arsenic, and antimony, and tin are present to an injurious
extent, and the ordinary methods of purifying or refining copper only remove these
impurities imperfectly.
Our Invention has for its object to remove the said arsenic, antimony, and tin
from the copper during the refining process, or to reduce the said arsenic, antimony,
and tin to such minute proportions as have no injurious effect on the copper.
Our said Invention consists of the improvements herein-after described in puri-
fying or refining copper, whereby any arsenic, antimony, or tin contained in the
copper operated upon is so effectually removed or reduced that from Chili bars and
other impure kinds of copper, such for example as the copper precipitated from
solutions of copper salts by means of metallic iron, we produce copper of a quality
equal to that known as best selected copper.
The ordinary method of refining copper consists in melting it and agitating it by
a rabble or stirring tool. The oxidising action of the air suffices for the removal
of ordinary impurities, and brings the copper into a sufficiently pure state for

page_text: commercial purposes; but where the copper to be refined contains arsenic, antimony,
or tin the oxidising action of the air does not effect the removal of these impurities,
or only removes them to an insufficient extent.
The treatment which constitutes our Invention subjects the melted copper to a
more powerful oxidising action than that of atmospheric air. The metallic
impurities referred to are effectually oxidised, and in their oxidised state enter and
are removed with the slag.
Our said improvements consist in treating the impure copper in a state of fusion
with a mixture of calcic hydrate (commonly called slaked lime) and copper scale or
oxide of copper; or with a mixture of calcic hydrate and haematite or peroxide of
iron; or with a mixture of calcic hydrate and peroxide of manganese.
The copper scale we employ is the scale produced in the rolling of copper, and
consists of oxide of copper.
Although we prefer to use copper scale, oxide of copper obtained from any other
source may be employed in place of copper scale.
The haematite we employ is a natural peroxide of iron, and we prefer it to an
artificially prepared oxide, although an artificially prepared peroxide of iron may
be employed, provided care be taken that it is of tolerable purity.
The oxide of iron obtained by roasting or burning iron pyrites is not suitable
for our process.
In employing haematite we select the purest qualities.
The peroxide of manganese we employ is the mineral commonly called black
oxide of manganese, but artificially prepared peroxide of manganese may be sub-
stituted for the mineral oxide. In either case we use the purest qualities obtain-
able.
Although we prefer to use the copper scale or oxide, and the haematite or per-
oxide of iron, and the peroxide of manganese mixed with calcic hydrate or slaked
lime, yet the crude soda called in commerce soda ash, which possesses the same
basic properties as calcic hydrate or slaked lime, and is not costly, may be used in
place of calcic hydrate.
The materials employed are reduced to a fine powder, and are then thoroughly
mixed together before being used.
The relative proportions of the materials which we have found to answer well
in practice are as follows. We do not however confine ourselves to these pro-
portions:-
When we use copper scale or oxide of copper we add to one part by weight of
the copper scale or oxide of copper three parts by weight of calcic hydrate or
soda ash.
When we employ haematite or peroxide of iron we add to one part by weight
of the said haematite or peroxide of iron two parts by weight of calcic hydrate or
soda ash.
When we employ peroxide of manganese we add to one part by weight of the
peroxide of manganese two parts by weight of calcic hydrate or soda ash.
Into a charge of copper to be refined, melted in a refining furnace, the said charge
consisting of seven or eight tons, we throw three cwts. of either of the mixtures
described above, and we thoroughly incorporate the mixture with the melted copper
by a process of rabbling. After the mixture has been thoroughly incorporated with
the melted copper the furnace is closed, and the temperature raised until the slag
formed is fit to be skimmed off. The process described is repeated until by trial
samples taken and examined in the usual way, the arsenic, antimony, and tin are
found to have been wholly removed, and the copper to have the properties of
selected copper.
The slags containing the arsenic, antimony, and tin, together with twenty or
thirty per cent. of copper, are either smelted with a reducing agent, and the metallic
opper obtained therefrom cast into cakes, or the said slags are smelted with
egulus or a sulphide ore of copper, the proportion of slag and regulus being so
djusted that the product formed shall contain fifty per cent. of copper.

page_text: After the slag has been carefully skimmed off in the process last referred to there
is added to the regulus a mixture of one part by weight of oxide of copper and
two parts by weight of soda ash in the proportion of about six cwts. of the said
mixture to four tons of the regulus. By rabbling the arsenic, antimony and tin
are oxidised, forming arseniate, antimoniate, and stannate of soda, the mixture of
which is skimmed off and thrown into a tank containing water. The water dis-
solves out the above salts, namely, arseniate, antimoniate, and stannate of soda;
any copper or copper compound being undissolved.
The proportions herein-before given of the several ingredients in the mixtures
we employ, and the proportions of the said mixtures to the copper or regulus under
treatment we have found to answer well in practice, but the proportions in each
case may be varied considerably without materially affecting the result.
Having now described the nature of our Invention, and the manner in which
'the same is to be performed, we wish it to be understood that we claim as our
Invention, the methods herein-before described of treating copper for the purpose
of purifying it from arsenic, antimony, and tin, that is to say, by treating it in the
refining furnace with a mixture of copper scale or oxide of copper, or haematite or
peroxide of iron, or peroxide of manganese with calcic hydrate or quicklime, or
with soda ash, substantially as described.
In witness whereof, we, the said John Wilkes and Thomas Johnson, have
hereunto set our hands and seals, this Thirteenth day of February, in the
year of our Lord One thousand eight hundred and seventy-nine.
Witness,
J. W. WILKES,
Birmingham.
JOHN WILKES.
(L.S.)
THOMAS JOHNSON. (L.S.)