JPH09143586A - Method for removing copper in molten iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and economically remove and recover copper, which is a impurity accompanying iron scraps, and to widen the range of application of the iron scraps to steel materials for which iron scraps had conventionally been unable to be used as a raw material. SOLUTION: This method for removing copper in a molten iron is to allow a solvent contg. alminium sulfide and iron sulfide to contact with the molten iron contg. copper to extract copper contained in the molten iron into the solvent. Next, the solvent is separated from the molten iron, and then the extracted copper is recovered from the solvent, and the solvent from which copper has been recovered is repeatingly used for the extraction of copper contained in the molten iron. Further, copper is recovered from the solvent separated from the molten iron by adding metal aluminium, etc., to the solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently removing copper mixed in iron scrap, and reusing iron and recovered copper. Further, the conventional iron scrap is used as a raw material. The present invention relates to an efficient and economical method for removing and recovering copper in molten iron, which enables utilization of steel scrap that could not be obtained and expands the scope of application of steel that can be used for iron scrap.

[0002]

2. Description of the Related Art Iron scrap is mainly melted in an electric furnace and reused as so-called electric furnace steel. This iron scrap usually contains various impurities such as copper. Copper, which is the main impurity of iron scrap, was manually removed by humans before the iron scrap was melted.
However, copper cannot be completely removed by manual selection, and copper that cannot be completely removed was melted and then mixed with blast furnace pig iron or iron scrap with less impurities, and diluted to a concentration within the specifications before use. So the types of steel available are limited.

Heretofore, as a method of removing copper from iron scrap, a method of immersing iron scrap in an ammonia solution to extract copper (for example, "decopperization of scrap scrap scrap"
-Copper decoppering by ammonia leaching method (2nd report)
− ”Resources and Materials Vol. 111, p. 55-58
(1995)), a method of vaporizing copper under high temperature (for example, “Decopper under vacuum”, Recyclable Element Separation Working Group Interim Report, Vol. 1, pp. 5-10 (1993) Japan Iron and Steel Association Special Research Group) (Circulating Elements Separation Subcommittee), a method of contacting with molten aluminum to dissolve copper in aluminum and remove it (for example, "Copper removal by aluminum bath" Recycling Elements Separation Subcommittee Interim Report Vol. 1, p. 43-49 ( 1
993) Japan Iron and Steel Institute Special Group Study Group, Separation of Cyclic Elements, "Search for Copper Removal Method from Iron Scrap by Thermochemical Method", Proceeding of the Japan Institute of Metals symposium p. 13-1
6 (1990)), a method of transferring copper to a solvent mainly containing sulfides of iron and alkali metals (for example, “FeS
Effect of Addition of Alkali and Alkaline Earth Metal Sulfides on Copper Partition between Flux and Molten Carbon Saturated Iron "Iron and Steel V
ol. 77, p. 644-651 (1991)).

[0004]

However, the above-mentioned methods for removing copper from iron scrap that have been proposed so far have low economic efficiency and have not been put into practical use. Therefore, the present invention
We proposed a method to more efficiently and economically remove and recover copper from molten iron that has melted iron scrap, enabling the use of steel scrap of steel materials that could not be used as a raw material in the past. It is an object of the present invention to provide a method for recovering copper in molten iron for expanding the range of application of steel materials that can be used for iron scrap.

[0005]

A first method for removing copper in molten iron according to the present invention is to bring molten iron containing copper into contact with a solvent containing aluminum sulfide and iron sulfide so as to be contained in the molten iron. Extracted copper into the solvent, then separating the solvent and the molten iron, and then recovering the extracted copper from the solvent,
It is characterized in that the solvent for recovering the copper is repeatedly used for extracting the copper contained in the molten iron.

Further, the second method for removing copper in molten iron of the present invention is based on the method for removing copper in molten iron of the first aspect of the present invention, which further comprises removing copper from the solvent separated from the molten iron. The recovery is performed by adding metallic aluminum, an aluminum alloy, scrap containing aluminum, or aluminum dross (hereinafter referred to as “aluminum-containing reducing agent”) to the solvent.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a solvent containing aluminum sulfide (Al ₂ S ₃ ) and iron sulfide (FeS) (hereinafter referred to as “Al ₂ S ₃ —FeS-based flux”, or simply “flux”). Has a high decoppering ability from molten iron, and when FeS is reduced by adding a strong reducing agent to the flux, copper is also reduced, and copper can be separated and recovered from the flux. is there.

When Al ₂ S ₃ -FeS type flux and molten iron containing copper are made to coexist, copper is sulfided by FeS in the flux and transferred into the flux as Cu ₂ S, and FeS which participated in the reaction becomes metallic iron. It is reduced and enters molten iron.
The capacity of this decoppering reaction is generally evaluated by the equilibrium partition ratio. The equilibrium distribution ratio is a value obtained by dividing the weight% of copper in the flux at the reaction equilibrium by the weight% of copper remaining in the molten iron.

When the Al ₂ S ₃ -FeS type flux and the molten carbon saturated iron are equilibrated at a temperature of 1400 ° C., the equilibrium distribution ratio is about 28 under the condition that the proportion of Fe in the flux is about 23% by weight. That is, the weight% of copper present in the flux after the copper removal reaction can be 28 times the weight% of copper remaining in the molten iron. When the composition of the flux deviates from this, the value of the equilibrium partition ratio becomes lower than this.
Therefore, the composition of the flux is such that the composition containing Fe, Al, S, and Cu is 70% by weight or more, and the ratio of Fe is 5 to 5.
It is preferably 40% by weight.

In this decoppering reaction, the molten iron does not necessarily have to be saturated with carbon, but the higher the carbon content, the higher the equilibrium distribution ratio and the lower the melting point of the molten iron. The temperature at which the molten iron is made to be lower can be lowered, and further, the sulfur concentration in the molten iron can be lowered, and the phase separation property between the flux and the molten iron can be enhanced. The reaction temperature for this copper removal is preferably in the range of 1200 to 1700 ° C.

Al ₂ S ₃ -FeS containing extracted copper
When the aluminum-containing reducing agent is added to the flux after separating the system flux from the molten iron, metallic aluminum enters the flux and is sulfided to form aluminum sulfide (Al
₂ S ₃ ) and instead of iron sulfide (Fe
S) is reduced to metallic iron (Fe), which is separated from the flux. When an aluminum-containing reducing agent is further added to the flux, copper sulfide (Cu
₂ S) is reduced to metallic copper (Cu), which is separated from the flux. Therefore, if the aluminum-containing reducing agent is added to the flux stepwise, it is possible to first obtain an alloy mainly composed of metallic iron and then an alloy mainly composed of metallic copper. Copper is separated from the flux and recovered. It becomes possible.

Since the flux after recovering copper can be repeatedly used for removing copper from molten iron, the method according to the present invention can remove copper in molten iron more efficiently and economically. Here, FeS in the flux which is repeatedly used for extracting copper from molten iron is insufficient, but as for that, pyrite (FeS ₂ ) or pyrrhotite (Fe
S) or the like may be added to supplement the insufficient FeS.

From molten iron to Al ₂ S ₃ -FeS type flux
Extraction of copper Al ₂ S used for Al ₂ S ₃ -FeS flux
₃ is a mixture of aluminum oxide (Al ₂ O ₃ , alumina) with a carbon source (for example, coke) and a sulfur source (for example, pyrite or elemental sulfur), and the temperature is raised to 1500 ° C or higher in an inert atmosphere such as nitrogen gas. It can be created by heating.

Further, more simply, the aluminum-containing reducing agent may be reacted with pyrite or / and pyrrhotite at a temperature of 1200 ° C. or higher. At this time, by adjusting the ratio of the aluminum-containing reducing agent and pyrite or / and pyrrhotite, an Al ₂ S ₃ —FeS-based flux having a desired composition can be prepared.

Once this flux is prepared and the copper removal process from molten iron of the present invention is started,
This flux is used repeatedly, and the A
Since the amount of l ₂ S ₃ becomes slightly excessive, it is not necessary to frequently create new flux.

The iron scrap to be decopperized is melted into molten iron using an electric furnace, and a carbon source (for example, coke) is obtained.
Add. By contacting the molten iron with an Al ₂ S ₃ —FeS-based flux, the copper in the molten iron is extracted into the flux. However, in order to more efficiently remove copper, the molten iron and the flux are contacted in several stages. Separately, the molten iron and flux at each stage are moved in a counter-current manner, and the copper in the molten iron is extracted into the flux in stages. That is, for the extraction of copper from the molten iron at the final stage, a new flux that has completed the copper recovery step is used. Then, the flux that has been used for copper extraction at the final stage until now is used for the extraction at the previous stage, so that the flux at each stage is sequentially fed to the previous stage. By doing so, the copper concentration in the molten iron obtained in the final stage can be efficiently reduced, and moreover, the copper concentration in the flux in the first stage can be increased. The flux concentrated copper in the first stage is sent to the copper recovery process. About three steps is suitable for copper extraction.

As the composition of the Al ₂ S ₃ -FeS type flux, it is possible to use one having a proportion of Fe of 5% by weight to 40% by weight. When the proportion of Fe in the flux is large, sulfur in the molten iron is used. Since the concentration becomes high, the load in the step of desulfurizing the molten iron after decoppering becomes large, and the amount of the aluminum-containing reducing agent required in the step of recovering copper from the flux also increases. Further, when the proportion of Fe in the flux is small, the amount of copper that can be concentrated in the flux is reduced, and the decoppering ability is reduced.

Therefore, in the final stage of copper extraction from molten iron, the Fe concentration in the flux is lowered to, for example, 15% by weight or less, and in the other stages, the Fe concentration in the flux is about 15% to 25% by weight. Is desirable. The Fe concentration in the flux is adjusted by adding pyrite, pyrrhotite, or elemental sulfur while the flux and molten iron are in contact with each other.

The Al ₂ S ₃ --FeS type flux is also effective for removing copper that accompanies solid-state iron scrap. Therefore, the front side of copper extraction (first stage, second stage
In such a step), copper extraction is performed with the solid iron scrap in place of the molten iron, and then a carbon source is added to the solid iron scrap to heat it to obtain molten iron.
It is also possible to perform copper extraction from molten iron. The temperature at which the solid iron scrap and the flux are contacted is 1200 to 150.
A range of 0 ° C. is appropriate.

Further, by bringing molten iron into contact with the Al ₂ S ₃ —FeS-based flux, it is possible to volatilize and remove a part of tin, which is an impurity in the molten iron, in the form of sulfide (SnS, etc.). When this flux is contacted with solid iron scrap, the volatilization of SnS can be promoted.

Since this Al ₂ S ₃ -FeS type flux has a high reactivity with oxygen or water vapor, the atmosphere in which the flux is placed is always protected by an inert gas such as nitrogen or argon. There is a need. When oxygen is mixed in the atmosphere, sulfurous acid gas (SO ₂ )
However, when water vapor is mixed in, hydrogen sulfide (H ₂ S) may be generated. Therefore, it is necessary to suck the atmospheric gas and detoxify the waste gas. Further, since carbon monoxide (CO) is generated as in the case of a normal steelmaking process, carbon monoxide is also detoxified by the waste gas treatment.
As a method of treating waste gas, a gas containing sulfur is oxidized to SO ₃ and then recovered as sulfuric acid or gypsum,
Carbon monoxide is also oxidized to carbon dioxide (CO ₂ ).

After the final stage of copper extraction, the molten iron is sent to a process similar to the general desulfurization process of pig iron to reduce the sulfur concentration in the molten iron, and further, the content of carbon, aluminum and other impurities in the molten iron. After adjusting the temperature, it is sent to a general steel manufacturing process. The amounts of carbon and aluminum in the molten iron can be easily reduced by the oxidation treatment.

Of copper from Al ₂ S ₃ -FeS based flux
The Al ₂ S ₃ —FeS-based flux that has completed the first stage of copper extraction from the recovered molten iron is sent to the copper recovery process. First, while maintaining the flux at a temperature of about 1300 to 1600 ° C., an aluminum-containing reducing agent is added to the flux to reduce about 70% of the amount of Fe in the flux, and a molten alloy mainly composed of metallic iron. Is separated and separated. At this time, a small amount of molten iron containing a large amount of carbon is previously made to coexist in the flux, and a carbonizing agent such as powdered coke or pulverized coal is preferably added together with the aluminum-containing reducing agent to assist in melting the precipitated metallic iron. If too much aluminum-containing reducing agent is added, the proportion of Fe in the flux becomes too low, and copper in the flux will migrate to the molten alloy phase at this stage, which is not preferable. The molten alloy composed mainly of metallic iron separated from the flux is merged with the molten iron before decoppering.

The flux with a reduced proportion of Fe is further added with an aluminum-containing reducing agent to reduce the remaining Fe and Cu in the flux and separate it from the flux as a molten alloy mainly composed of metallic copper. The reaction temperature is 120
A range of 0 to 1600 ° C is suitable. The amount of the aluminum-containing reducing agent added here is in excess of the amount that stoichiometrically reduces FeS and Cu ₂ S in the flux,
The residual aluminum is allowed to enter the molten alloy mainly composed of metallic copper. By this operation, the proportion of Cu remaining in the flux is reduced to 1% by weight or less.

The operation of reducing and recovering Cu from this flux is divided into several steps, and the molten alloy in which the flux and aluminum of each step are left is moved in a counter-current system so that Cu in the flux is gradually melted. It is efficient to extract them. In other words, a new reducing agent containing metallic aluminum was used for the recovery of copper from the flux in the final stage, and the molten alloy in which aluminum remained was used for recovery of copper from the flux in the preceding stage, Similarly, the molten alloy in which aluminum in each stage is left is sequentially fed to the preceding stage of copper recovery.

The finally obtained molten alloy containing copper, iron and aluminum is separated from the flux and solidified, and then sent to a copper refinery or the like.

After recovering the copper, the flux is sent again to the final stage of copper extraction from the molten iron, and the decoppering from the molten iron is repeated. Here, when FeS in the flux is insufficient,
Under the condition that the flux coexists with molten iron, pyrite, pyrrhotite, elemental sulfur, or the like is added to supplement the deficient FeS.

By repeatedly using this flux,
The amount of Al ₂ S ₃ in the flux may be slightly excessive. In that case, when the copper recovery from the flux is completed, the surplus flux is separated. As a method of treating excess flux, after cooling and solidifying, it is oxidized using a rotary kiln or the like to obtain aluminum oxide. In this method, since waste gas containing sulfurous acid gas is produced, waste gas treatment is performed to fix the sulfurous acid gas as gypsum or sulfuric acid.

Further, the cooled excess flux can be thrown into an aqueous solution and used for the production of hydrogen sulfide (H ₂ S) and aluminum hydroxide.

Further, the surplus flux is set to 1200 to 160.
Aluminum chloride (AlCl ₃ ) is allowed to coexist with molten iron at a temperature of 0 ° C. and reacted with a gas containing chlorine gas (Cl ₂ ).
And FeS are produced, aluminum chloride is volatilized and recovered, and FeS can be used again for decopperization from molten iron.

[0031]

[Example] From molten iron obtained by melting iron scrap, Al ₂
S ₃ 3-stage countercurrent system copper extraction into -FeS based flux, showing an embodiment of the present invention carried out in counter-current system of the two-stage recovery of copper from the flux into the molten alloy.

As the pre-treated iron scrap, one having an initial copper concentration of about 1% by weight was used. This iron scrap was put into an arc melting furnace together with powder coke and melted to obtain molten iron containing 3% by weight or more of carbon.

The initial Al ₂ S ₃ -FeS system flux was
Scrap aluminum and pyrite were gradually charged into an arc melting furnace containing molten iron maintained at a temperature of 1200 to 1400 ° C. to form on the upper surface of the molten iron phase. In the subsequent steps, scrap aluminum having a composition containing 90% by weight or more of metallic aluminum was used. The flux composition is such that the ratio of Fe is about 15% by weight by adjusting the ratio of scrap aluminum and pyrite.
It was made to become. At this time, nitrogen gas was introduced into the arc melting furnace to prevent decomposition of the generated flux. The generated flux was taken out from the arc melting furnace and sent to the following copper extraction process from molten iron.

As mentioned above, this Al ₂ S ₃ -F is once used.
Once the eS-based flux is created, the flux is repeatedly used, and the amount of Al ₂ S ₃ in it is slightly excessive, so that it is not necessary to create new flux frequently.

Extraction of copper into Al ₂ S ₃ —FeS-based flux
In the first step of copper extraction from molten iron in the output step , first, the Al ₂ S ₃ —FeS-based flux was put in the first-stage dedicated electric furnace. This flux has already contained copper to some extent in the second stage copper extraction. When starting the process,
The flux synthesized in the pretreatment described above was used.

The shape of the electric furnace is kettle-like, has a lid so as to maintain airtightness, the inner wall is made of refractory brick, and the temperature is maintained by energizing the melt from the carbon electrode. It also has a gas burner to preheat the furnace. In order to prevent the oxidation of the flux, the electric furnace has a structure that allows nitrogen or argon gas to be introduced from the lance, and is equipped with ducts for sending the gas introduced into the electric furnace and the gas generated from the electric furnace to the processing equipment. There is.

Scrap containing molten copper which has been melted in the pretreatment is introduced into the electric furnace through the molten iron charging port of the lid, and the flux and molten iron are agitated at the bottom of the electric furnace to convert the copper in the molten iron into the flux. I made a transition. The reaction temperature is about 14
The temperature was set to 00 ° C., and the weight ratio of flux to molten iron was set to about 1: 5. At this point, the target composition of the flux was an Fe content of about 15% by weight, and if the Fe content was lower than that, pyrite was added to the electric furnace. Subsequently, nitrogen or argon gas was sprayed onto the flux and the molten iron from the lance to stir the mixture to promote the reaction, and then the mixture was allowed to stand to separate the flux and the molten iron. After the separation of both phases, the electric furnace was tilted and the flux and a small amount of molten iron were poured out and sent to the step of recovering copper from the flux. Next, the remaining molten iron was poured out from the electric furnace and sent to the second stage copper extraction step.

The copper concentration in the flux after the completion of the reaction in the first stage is about 6% by weight, and the copper concentration in the molten iron is about 0.
It became 3% by weight.

In the second stage of copper extraction from molten iron, first,
The second flux after the third stage copper extraction, which is the final stage
I put it in the electric furnace for the first stage. At the time of starting the process, the flux synthesized in the above-mentioned preliminary treatment was used. The form of the electric furnace of the second stage is similar to that of the first stage.

Next, the molten iron that had been subjected to the copper extraction in the first stage was introduced from the molten iron inlet of the lid of the electric furnace, and the copper in the molten iron was transferred to the flux in the same manner as in the copper extraction in the first stage. The reaction temperature was about 1400 ° C., and the weight ratio of the flux to the molten iron was about 1: 5. At this point, the target composition of the flux was an Fe content of about 21% by weight, and when the Fe content was lower than that, pyrite was added to the electric furnace. Also in the second stage, as in the first stage, nitrogen or argon gas was sprayed onto the flux and molten iron from the lance to stir the mixture to promote the decoppering reaction, and then allowed to stand. After the separation of the flux and molten iron, the electric furnace was tilted and the flux was first poured out and sent to the first stage copper extraction step. next,
Molten iron was poured out and sent to the third stage copper extraction step.

The copper concentration in the flux after completion of the reaction in the second step was about 2% by weight, and the copper concentration in the molten iron was about 0.1% by weight.

In the third stage of copper extraction from molten iron, first,
The flux that had undergone the copper recovery step was placed in the third-stage dedicated electric furnace. At the time of starting the process, the flux synthesized in the above-mentioned preliminary treatment was used. The form of the third-stage electric furnace is the same as that of the first-stage and second-stage.

Next, the molten iron that had been subjected to the second stage copper extraction was introduced from the molten iron inlet of the lid of the electric furnace, and the first and second stages were introduced.
The copper in the molten iron was transferred to the flux in the same manner as the copper extraction in the first stage. The reaction temperature was about 1400 ° C., and the weight ratio of the flux to the molten iron was about 1: 5. At this point, the target composition of the flux was an Fe content of about 11% by weight, and if the Fe content was lower than that, pyrite was added to the electric furnace. Also in the third stage, as in the first and second stages, nitrogen or argon gas was sprayed onto the flux and molten iron from the lance to stir them to promote the decoppering reaction, and then allowed to stand. After separating the flux and molten iron,
First, the electric furnace was tilted to flow out the flux, and the flux was sent to the second stage copper extraction step. Next, the molten iron that had been decopperized was poured out and sent to a general desulfurization process. In the desulfurization process, lime, soda ash (Na ₂ CO ₃ ) and the like are added to remove S in the molten iron, and then oxygen is blown in the converter to reduce the carbon content and aluminum content of the molten iron. Molten iron was sent to a general steel manufacturing process.

After the completion of the reaction in the third stage, the copper concentration in the flux was about 1.2% by weight, and the copper concentration in the molten iron was about 0.07% by weight.

Of copper from Al ₂ S ₃ -FeS based flux
The Al ₂ S ₃ —FeS-based flux that had completed the first stage of copper extraction from the molten iron was sent to the copper recovery step together with a small amount of molten iron.

First, the flux and a small amount of molten iron are charged into an electric furnace for removing iron from the flux, scrap aluminum and powder coke are added little by little to the flux, and FeS in the flux is reduced to metallic iron, Transferred to molten iron phase. When the Fe concentration in the flux reached about 5 to 10% by weight, the addition of scrap aluminum and powder coke was completed, and after standing, the electric furnace was tilted to flow out the flux, which was then recovered from the copper. It was sent to the first-stage electric furnace. Subsequently, the molten iron phase was poured out, which was combined with the molten iron before the copper extraction in the pretreatment. The temperature in the furnace in this reaction was 1500 ° C, and when the amount of heat was insufficient, electricity was supplied from the carbon electrode. Also, nitrogen was introduced as an inert gas into the electric furnace to prevent the oxidation of the flux, and the waste gas was sent to the treatment facility through a duct.

The flux from the deironing electric furnace was charged into the first stage electric furnace for copper recovery, and then the molten alloy obtained in the second stage copper recovery was charged therein. This molten alloy is composed of copper and iron recovered from the flux in the second stage of recovering aluminum and copper. At the time of starting the process, new scrap aluminum was used in place of this molten alloy.

The temperature setting of the first stage electric furnace for copper recovery is about 14
When the temperature was set to 00 ° C. and the temperature was lower than this, the amount of heat was supplemented by energization from the carbon electrode. Blow nitrogen onto the flux and molten alloy using a lance, stir both,
FeS and Cu ₂ S in the flux were reduced with aluminum in the molten alloy, transferred to the molten alloy as metallic iron and metallic copper, and then allowed to stand. Waste gas was sent to the treatment facility through a duct. After the flux and molten alloy are separated, tilt the electric furnace to flow out the flux,
It sent to the electric furnace of the stage. Next, the molten alloy was poured out of the electric furnace and solidified, and then the alloy was sent to a copper smelting plant.

The composition of the molten alloy obtained here was about 30% by weight of copper, about 45% by weight of iron and about 25% of aluminum.
% By weight.

In the second stage of copper recovery, the flux from the first stage of copper recovery and then the scrap aluminum were charged to the electric furnace of the second stage of copper recovery. The amount of scrap aluminum charged was FeS and C in the flux at the time when it was sent from the deferring electric furnace to the first stage electric furnace for copper recovery.
u ₂ S was made to be 1.3 to 2.5 times the amount of aluminum that can be stoichiometrically reduced.

The temperature of the second stage electric furnace for copper recovery was set to about 1400 ° C. as in the first stage, and when the temperature was lower than this, the amount of heat was supplemented by energizing from the carbon electrode. Nitrogen is blown onto the flux and scrap aluminum using a lance, both are stirred, FeS and Cu ₂ S remaining in the flux are reduced with aluminum, and a molten alloy is formed with the remaining aluminum as metallic iron and metallic copper. It was Then, it left still and the flux and molten alloy phase were isolate | separated. When the separation of both phases became insufficient, an alloy containing a small amount of molten iron or lead was charged into the electric furnace to increase the specific gravity of the molten alloy. Waste gas was sent to the treatment facility through a duct. After the flux and the molten alloy were separated, the electric furnace was tilted to flow out the flux. Next, the molten alloy was poured out from the electric furnace and sent to the first-stage copper recovery electric furnace.

By this copper recovery step, C in the flux
The u content was 1 wt% or less, and the Fe content was 1 wt% or less. This flux is the third of copper extraction from molten iron.
Repeated on the stage. In addition, when the flux became excessive, a part of the flux was taken out at this point and was oxidized using a rotary kiln to render it harmless as aluminum oxide. The waste gas was sent to the treatment facility through a duct, and the generated sulfurous acid gas was fixed as gypsum to render it harmless.

By this process, the concentration of the impurity copper in the iron scrap can be reduced from about 1% by weight to 0.1% by weight or less, and the copper recovery rate becomes 90% or more. The amount of scrap aluminum and pyrite used is about 20 kg and about 55 on average per ton of iron scrap.
kg.

In the process of removing copper in molten iron without repeated use of flux, the amounts of scrap aluminum and pyrite used are as follows:
They are about 45 kg and about 240 kg, respectively. Therefore, the method according to the present invention in which the flux is repeatedly used has a consumption of scrap aluminum of 1/2 or less and a consumption of pyrite of 1/4 as compared with the method in which the flux is not repeatedly used.
It can be reduced to less and is more economical.

[0055]

According to the present invention, the removal and recovery of copper in iron scrap can be performed more efficiently and economically.
Steel scrap that could not be used as a raw material can be used for iron scrap, and the applicable range of steel materials that can use iron scrap can be expanded.

Claims (2)

[Claims] 1. A molten iron containing copper is brought into contact with a solvent containing aluminum sulfide and iron sulfide to extract copper contained in the molten iron into the solvent, and then the solvent and the molten iron are separated from each other. Separation, then, the extracted copper is recovered from the solvent, the solvent recovered copper is repeatedly used for extraction of copper contained in the molten iron, removal of copper in molten iron Method. 2. The method for recovering copper from a solvent separated from molten iron by adding metallic aluminum, an aluminum alloy, scrap containing aluminum, or aluminum dross to the solvent.
The method for removing copper in molten iron according to.