Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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OPERATION METHOD OF COPPER SMELTING
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to an operation method of copper smelting,
more particularly to a method for treating precious metal in a converter or an
anode
furnace used in the copper smelting process.
2. Background Technique
Various methods are implemented in the smelting process of copper sulfide
ore. A representative process comprises smelting of copper-sulfide ore
concentrates in
a flash furnace or the like to produce matte, treating the matte in a
converter to produce
crude copper having approximately 98.5 mass % of copper content, refining the
crude
copper in an anode furnace to enhance the copper content up to 99.3 mass % to
99.5
mass %, casting the refined copper into anodes, and finally subjecting the
anodes to
electrolytic refining to produce electric copper having 99.99 mass % or more
of purity.
During this process, precious metals such as gold, silver and platinum
contained in the
raw material are concentrated in the sludge yielded in the electrolytic
refining.
Precious metal is used for ornamentals, lead frame of IC, catalyzer of
automobile exhaust-gas, an exhaust-gas sensor, dental materials and the like.
The
precious metal is recycled in two forms, that is, scraps or other
miscellaneous industrial
waste. The scrap of precious metal is usually subjected to the wet recovering
process
(c.f., JOURNAL OF THE MINING AND MATERIALS PROCESSING INSTITUTE OF
JAPAN) Vol. 113 (1997) No.12, Great Special Edition of Recycling, pages 1115 -
1117).
It is known from Great Special Edition of Recycling, ditto, pages 1173 - 1174
that the
industrial waste containing precious metal is calcined and sieved and is then
returned
to the copper smelting process.
The copper ore, flux components and recycling raw material in the powder
form are blown into the shaft of a flash furnace together with oxygen and are
then
rapidly subjected to reactions to form matte and slag. The matte and slag are
stored in
a hearth and then separated into upper and lower layers under gravity
difference.
The matte produced in the smelting furnace is treated in a converter to
attain the following conversions. That is, the iron contained in the matte is
oxidized
and the resultant oxide is separated in the slag phase, and the sulfur bonded
with the
iron of the matte is separated in the gas phase. White matte is thus yielded
in the
slag-making process. In the subsequent copper-making process, the sulfur of
the white
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matte is separated in the gas phase, and crude copper is yielded.
The crude copper yielded in the converter is subjected to the oxidizing and
reducing steps in the anode furnace to remove excess sulfur and oxygen. The
refined
copper is cast into an anode having the appropriate shape for electrolytic
refining.
The platinum group elements indicated herein are Pt, Pd, Rh, Ru, Ir and Os
and are referred to as PGM hereinafter. The raw material in the powder form 1
mm or
less of size containing PGM has heretofore been charged into the flash furnace
together
with the copper ore and flux. Since PGM contained in the raw material powder
has
affinity to Cu in the high-temperature melt, major portion of PGM is included
into the
anode, and is electrolytically separated from Cu into sludge. The sludge is
then
subjected to the known refining process to separately recover each element of
PGM.
Japanese Unexamined Patent Publication (kokai) No. 57-32339 entitled
Operation Method of Copper Smelting Converter proposes to charge the silicate
ore or
silica stone through tuyeres of a converter. However, this publication does
not mention
a step of blowing the recycling material through the tuyeres.
Japanese Unexamined Patent Publication (kokai) No. 57-192233 entitled
Operation Method of Copper Smelting Converter limits the materials charged
into the
converter through the tuyeres to the ore or ore-concentrate in the form of
powder, and
the flue dust generated in the copper smelting. However, this publication does
not
mention a step of blowing the recycling material through the tuyeres.
DISCLOSURE OF INVENTION
1. Problem to be Solved by the Invention
The present inventors investigated in detail the behavior of the recycling
material containing PGM charged into a flash furnace and discovered the
following
facts. When the raw material in the powder or granular form containing a large
amount of PGM is charged into a flash furnace, approximately 10 % of the
respective
elements of PGM is transferred into slag. As is described hereinabove, the raw
materials charged into a flash furnace are brought into reactions and are then
separated into matte containing copper and slag containing most of the
impurities.
The matte and slag are separated into the lower and upper layers,
respectively, due to
the gravity difference. Most of the copper and precious metal transferred into
the slag
are not recovered but are lost.
Presumably, PGM is transferred into the slag, because the ultra fine
particles among PGM, such as the ground powder of the ornamentals and dental
alloy,
has such slow settling velocity in the slag in the flash furnace that the PGM
is not
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brought into contact with the underlying matte. The slag containing PGM is
tapped
from the flash furnace. In addition, since PGM has a very high melting point,
its
melting time is prolonged.
The present inventors conceived then an idea that the recovering ratio of
PGM can be enhanced by means of blowing the recycling material through a
tuyere(s) of
the converter or the anode furnace into the molten white matte or molten crude
copper,
thereby causing direct reaction of the PGM with the white matte crude copper.
It is, therefore, an object of the present invention to improve the operation
object of the operation method of copper smelting, in which recycling material
containing one or more elements of PGM, namely, Pt, Pd, Rh, Ru, Ir and Os, are
treated
in the flash furnace, in such a manner that the lost PGM is recovered to
enhance the
recovering ratio of PGM.
2. Means for Solving Problem
In accordance with the objects of the present invention, the recycling
material containing one or more elements of PGM is not charged into the flash
furnace
but is charged into the converter or anode furnace by the following methods.
(1) An operation method of copper smelting, characterized in that the
recycling material in powder or granular form containing one or more elements
of PGM
is blown through a tuyere or tuyeres of a converter or an anode furnace and is
brought
into direct contact with the white matte or crude copper, thereby
concentrating PGM
in the crude copper.
(2) An operation method of copper smelting according to (1), wherein the
recycling material, which contains one or more elements of PGM, has 3mm or
less of
particle size and is dried to 10 mass % or less of moisture.
(3) An operation method of copper smelting according to (1) or (2),
wherein the recycling material, which contains one or more elements of PGM, is
blown
through one or more selected tuyeres of the converter or the anode furnace.
(4) An operation method of copper smelting according to any one of (1)
through (3), wherein the recycling material, which contains one or more
elements of
PGM, is blown into the converter during the copper-making stage.
According to an aspect of the invention there is provided an operation
method of copper smelting comprising producing a matte and treating the matte
in
a converter to produce crude copper, wherein the method comprises blowing a
recycling material containing a platinum-group metal which is Pt, Pd, Rh, Ru,
Ir,
Os, or any combination thereof, hereinafter referred to as PGM, in powder or
granular form, into the converter, wherein the PGM has a particle size of 3mm
or
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less and is blown through a tuyere or tuyeres of the converter during the
copper
production stage, thereby concentrating PGM in the crude copper.
According to another aspect of the invention there is provided an operation
method of copper smelting comprising producing a matte, treating the matte in
a
converter to produce crude copper and refining the crude copper in an anode
furnace for producing copper to be subjected to electrolytic refining, wherein
a
recycling material containing a platinum-group metal which is Pt, Pd, Rh, Ru,
Ir,
Os, or any combination thereof, hereinafter referred to as PGM, is brought
into
contact, in powder or granular form, with the crude copper, wherein the PGM
has
a particle size of 3mm or less and is blown into the anode furnace through a
tuyere
or tuyeres of the anode furnace, thereby concentrating PGM in the crude
copper.
DESCRIPTION OF PREFERRED EMBODIMENTS
The recycling material treated by the method of the present invention contains
one or more elements of PGM, i.e., Pt, Pd, Rh, Ru, Ir and Os. The content of
each element
is usually from a few ppm to a few mass%, specifically, lppm to 5 mass%. More
specifically, the Pt content is from 50 g/t (50 ppm) to 1000g/t (0.1%) and the
Pd content
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is from 100 g/t (100 ppm) to 5000 g/t (0.5%).
The recycling material may have any composition provided that it can be
smelted in a converter or an anode furnace, and its PGM can be separated from
the
major portion of the recycling material. Since the recycling material
originates from
almost all of industries, it is difficult to specify the components of the
recycling material.
An example of the balance of PGM is usually from 0 to 95 mass % of metal, such
as Fe,
Cu, Al and the like, from 0 to 95 mass % of their oxides, from 0 to 95 mass %
of sulfides
of Fe and Cu, S102, A1203, as well as from 0 to 95 mass % of calcined C of the
plastics,
which derive from the industrial waste.
The properties of the recycling material should be such that it does not clog
the
blowing tubes. The recycling material should therefore be preliminarily dried
to 10
mass % or less of moisture and any coarse grains or pieces of the recycling
material
should be preliminarily refined to 3 mm or less. Drying is carried out by
means of for
example a steam drier at a temperature of from 100 to 150CC. A sieve is used
to adjust
the size of the recycling material to eliminate foreign matters mixed in the
recycling
material.
In an embodiment of blowing the recycling material into a PS converter, the
recycling material is blown preferably not during the slag forming stage, in
which the
slag and the white matte are co-present in the furnace, but during the copper-
making
stage, in which the white matte and crude copper are co-present, so as to
avoid the
transferring of PGM into the slag and hence the PGM loss. Blowing of the
recycling
material during the copper-making stage is preferable because of the following
specific
reasons. Since the slag-making stage is for approximately 1 hour and is
relatively
short, while the copper-making stage is for approximately 3 hours and is
relatively long,
the melting time of PGM can be kept for a long period of time by means of
blowing the
recycling material during the copper-making stage. In addition, the recycling
material,
which is blown during the slag-making stage and may not be molten, is
transferred into
the slag and is lost, while the recycling material, which is blown during the
copper-making stage but is not yet molten, is transferred into the mush. In
the next
converter operation, the-mush is vigorously reacted with the matte, which is
supplied
from a smelting furnace, e.g., a flash furnace and is again transferred into
the matte.
A furnace for treating the recycling material is a smelting furnace of matte,
such as a PS converter, or a subsequent refining furnace, e.g., anode furnace.
The
anode furnace is used in a case where the amount of the recycling material
small, and
further the amount of the impurities, which exert detrimental influence upon
the
subsequent electrolytic refining process, is at a low level The anode furnace
is less
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preferable than the converter for treating the recycling material, because the
anode
furnace belong to the final stage for preparing the anode, and the impurities
added from
the recycling material to the anode material should later be removed, which is
disadvantageous.
5 A number of the tuyeres, through which the recycling material is blown, is
dependent upon the amount of the recycling material, and may be only one or
all of the
tuyeres. Diameter of the tuyeres is usually from 42.9 to 50.8 mm. Appropriate
amount of the recycling material blown per operation may be approximately 0.5
to 5
tons.
BRIEF DESCRIPTION OF DRAWING
Figure 1 illustrates a plant for blowing the recycling material containing one
or more elements of PGM into a converter according to an embodiment of the
present
invention.
EXAMPLES
Example 1
A test for treating the recycling material 10 ton in total was carried out for
4
days using a converter operated for the commercial production of copper. One
ton of the
recycling material was blown into the converter during its each operation.
Figure 1 shown a plant used for the test.
The data in average of the test for 4 days are described in the following.
The recycling material contained 299 g/t of Pt and 1644 g/t of Pd. The other
components of the recycling material were 19 % of Si, 14 % of Al, 11 % of Ba,
9 % of Fe,
5 % of Ca, 4 % of S, 4 % of Ni, 3 % of Cu, 3 % of Zn in terms of the metallic
elements.
The recycling material was sieved to 3 mm or less and dried at 135`C using a
steam
drier to 2 mass % or less moisture and occasionally to 10 mass % of moisture
and then
stored in the blowing tank 1. High-pressure air generated in the compressor 2
was
conveyed through the drain-separator 3 and the drier 4 at a rate of 7.8Nm3/min
and was
used as carrier gas of the recycling material at a rate of from 5 to 50
kg/minute. The
obtained solid - air mixture was blown through a tuyere 6 into the melt 7,
which was
formed in the copper-making stage and the white matte and the crude copper
were
co-present. Clogging of the blowing pipe 11 did not occur. In addition, the
steam
explosion did not occur in the converter 10 during the blowing of the solid-
air mixture
mentioned above.
The balance of Pt and Pd is shown in Table 1, with the proviso that the blown
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amount of Pt and Pd amounts to 100%, respectively..
Table 1
Crude Converter Converter
Copper of Dust Slag
Converter
Transfer Ratio of Pt (%) 98.6 1.1 0.3
Transfer Ratio of Pd (%) 98.1 0.5 1.4
The crude copper was totally tapped into the ladle and then poured in an
anode furnace. The converter slag remained partly in the converter, and then
the next
converter operation was started so that converter slag was again formed. The
total of
the remaining slag and the slag again formed were tapped in the next
operation. The
converter slag in Table 1 indicates this total slag.
As shown in Table 1, 98.6 % of Pt and 98.1 % of Pd of the recycling material
was transferred to the crude copper formed in the converter. This ratio
indicates more
efficient recovery of Pt and Pd than that by means of charging the recycling
material
into the preceding flash furnace. Note that the transfer ratio into the slag
is
approximately 10% in the case of charging into the flash furnace. The Cu grade
of the
resultant crude copper was as usual.
Example 2
The same recycling material as in Example 1 in amount of 5 ton was blown
into an anode furnace operated for the commercial production of copper. The
balance
of Pt and Pd is shown in Table 2. The Cu grade of the resultant refined copper
was as
usual.
Table 2
Refined Anode Furnace
Copper Dust
Transfer Ratio of Pt (%) 99.6 0.4
Transfer Ratio of Pd (%) 99.7 0.3
INDUSTRIAL APPLICABILITY
When the recycling material containing PGM is treated in the copper smelting
process, the recycling material is charged into a converter or an anode
furnace. In this
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case, the recycling material is not brought into direct contact with the slag.
The slag
loss of PGM can, therefore, be avoided, and recovery ratio of PGM amounting to
98% or
more is attained.
