KR101368575B1 - Method for separating and recovering elements coexisting in scrap iron - Google Patents

Abstract

The present invention is a method for efficiently and economically separating and recovering elements such as copper, which coexist in iron scrap, by melting iron scrap and bringing molten iron scrap into contact with molten Ag, thereby melting and melting the iron scrap. Based on the distribution equilibrium between Ag, an element coexisting in iron scrap is transferred to molten Ag, and a method for oxidizing and removing the element transferred to molten Ag from molten Ag is provided. It is preferable that the molten iron scrap contains C, and it is more preferable that C is saturated and dissolved.

Description

Separation and recovery method of elements coexisting in iron scrap {METHOD FOR SEPARATING AND RECOVERING ELEMENTS COEXISTING IN SCRAP IRON}

The present invention relates to a method for separating and recovering elements coexisting with iron in iron scrap, particularly metal elements such as tramp elements.

The accumulation of iron scrap in Japan is increasing year by year, and it is expected to reach about 1.8 billion tons in 2020, generating 50 million tons of iron scrap a year. In commercial iron scrap, it is difficult to remove from iron, and impurity components other than micro iron, which adversely affect the quality or manufacturing process of steel, specifically Cu, Ni, Cr, Sn, Zn, Sb, As, Bi, Pb, and Mo are illustrated (henceforth a "tramp element"), and many are included. For this reason, use as a raw material of the high quality steel which Japan steel industry is proud of is restrict | limited.

In addition, these days, the problem of the rise and depletion of useful rare metals in addition to iron resources has arisen. In this case, the iron scrap contains not only copper and chromium but also useful metals (W, Mo, Co, Ni, V, Nb, etc.). Therefore, when it is possible to efficiently separate the components other than the fine iron contained in the iron scrap and recover them, it is necessary to expand the utilization in Japan without exporting the iron scrap generated in Japan. It becomes possible.

As a method for removing copper from iron scrap, there is a technique of removing copper from molten iron by using a distribution of copper between sulfides of iron-alkali metal and alkaline earth metal and carbon saturated iron (Non Patent Literature 1).

In this method, it is possible to achieve a decopper ratio of 65 to 75% in 100 Kg / t-metal flux units, but the decopper efficiency is not sufficient. In addition, since the amount of flux needs to be increased in order to improve the copper removal rate, there is a problem from an economic point of view.

Moreover, since the sulfide flux containing a large amount of alkali metal is used, the process of the flux after a decopper process also becomes a problem.

Patent Document 1 reports a method of selectively reacting copper with iron using chlorine gas and removing it as a gas. Since this method uses chlorine gas, it is necessary to make the reaction vessel completely hermetic. In addition, it is necessary to form a reaction vessel made of a material that does not react with chlorine.

An evaporation refining method for selectively evaporating copper under vacuum is also proposed. However, to increase the evaporation rate a high temperature of at least 1873K and high vacuum of at least 100 Pa is required. Moreover, since the reaction system area sufficient for practical use calculated from the evaporation rate is very large, it is difficult to develop into an actual process (Non-Patent Document 2).

Patent Literature 2 proposes a technique for removing copper by once transferring copper in an iron scrap to a lead alloy and then transferring copper in the lead alloy to a metal melt containing aluminum.

However, in this technique, it is necessary to separately perform the transfer of copper to lead alloy in iron scrap and the transfer of copper to metal fusion including aluminum in lead alloy for molten iron. For this reason, removal of copper cannot be advanced continuously.

In addition, in the transition of copper from iron scrap to lead alloys, distribution of copper to lead alloys for iron (equilibrium distribution ratio of copper = [mass% Cu] _{in Pb} / [mass% Cu] _{in Fe -C} , where [% by mass Cu] _{in Pb} is the copper concentration in lead [mass% Cu] _{in Fe- C} means copper concentration in iron.) Is as small as 2: 1. For this reason, in order to remove copper from iron, a large amount of lead alloys are required.

As mentioned above, the copper removal method from the iron scrap conventionally proposed has a problem from the efficiency and the economic viewpoint, and it did not reach practical use.

Patent Document 1: Japanese Unexamined Patent Publication No. 6-248364 Patent Document 2: Japanese Patent Application Laid-Open No. 10-110224

[Non-Patent Document 1] Wang Chao, Nagasaka Tetsuya, Hinomitsu, Banya Shiro: Iron and Steel, 77 (1991), 644-651. [Non-Patent Document 2] H. Ono-Nakazato, K. Taguchi, Y. Seike and T. Usui: ISIJ International, 43 (2003), 1691-1697.

The present invention proposes a method for efficiently and economically separating and recovering elements such as copper, which coexist in iron scrap, and aims to expand the use of iron scrap.

As a result of the investigation by the present inventors, even in the case of elements coexisting in iron scrap, even in the case of an element which is difficult to separate from molten iron in ordinary oxidation refining, by indirectly oxidizing and removing the molten Ag having a low solubility in the melt of the iron scrap as a medium The knowledge that the said subject can be solved was acquired.

Cu is an example of an element that is harder to oxidize than Fe and is difficult to separate from molten iron in conventional smelting. Hereinafter, this knowledge is demonstrated in detail using this Cu as a specific example. Through molten Ag having a particularly low solubility in the melt of the iron scrap, oxygen can be oxidized and removed to recover Cu by spraying oxygen on the surface of the molten Ag that is not in contact with the melt of the iron scrap.

When Cu is contained in Fe phase, Fe will preferentially oxidize with respect to Cu. For this reason, the reaction of the following formula (2) cannot normally proceed.

Thus, using Ag having a particularly low solubility in the melt of the iron scrap, the distribution of Cu between the melt of the iron scrap and the molten Ag (Equation 3 below) and the oxidation of Cu in the molten Ag (Equation 4 below) By continuously proceeding, the reaction of formula (3) + formula (4) = formula (2), that is, oxidative refining of Cu in the melt of the iron scrap can be realized.

The element that can be separated on the basis of the above principle is an element that is more easily oxidized than Ag, and is an element that can be dissolved in the melt of the iron scrap and the molten Ag, that is, the element distributed at the interface between the melt of the iron scrap and the molten Ag.

Moreover, when the melt of an iron scrap contains C, it becomes possible to collect | recover the said element more efficiently.

The present invention provided on the basis of the above findings is, in one aspect, a method for separating and recovering elements coexisting in iron scrap, by melting the iron scrap, and contacting the molten Ag of the obtained iron scrap with molten Ag. A step of transferring the elements coexisting in the scrap to the molten Ag and the step of oxidizing and removing the elements transferred to the molten Ag from the molten Ag are separated and recovered.

When the iron scrap is melted and the molten Ag of the obtained iron scrap is brought into contact with the molten Ag, based on the distribution equilibrium between the molten iron scrap and the molten Ag, the molten iron scrap melts into molten Ag and coexists with iron in the iron scrap. The elements to be described (hereinafter also referred to as "coexistence elements") are transferred.

In addition, "oxidation removal" means that the atmosphere near the surface of the molten Ag is strongly oxidized by using means such as oxygen injection, thereby oxidizing an element that is more easily oxidized than Ag among the elements contained in the molten Ag. This means removing from the molten Ag phase as an oxide insoluble in the molten Ag.

It is preferable to perform the melting of the iron scrap and the contact of the molten iron scrap with the molten Ag in a non-oxidizing atmosphere.

It is preferable that the molten iron scrap contains C, and the concentration N _C (unit: mass%) satisfies the following formula (1):

N _C ^≦ 10 ^{12 .728 / T + 0. 7271 × logT -3.049} (1)

Where T is the temperature of the melt of the iron scrap and is greater than 1426K and less than 1873K.

By melting the iron scrap together with the carbon source, a melt of the iron scrap containing C may be obtained.

It is preferable that the melting of the iron scrap, the melting of the iron scrap, and the contact of the molten Ag are performed in a graphite crucible so that C is saturated and dissolved in the melt of the iron scrap.

The element to be separated and recovered may include a tramp element.

The element to be separated and recovered may include one or two or more selected from the group consisting of W, Mo, Co, V and Nb.

In the present invention, the elements coexisting in the iron scrap can be oxidized and removed by using molten Ag having a particularly low solubility in the melt of the iron scrap. For this reason, efficient recovery of the tramp element and the useful rare element from the iron scrap is realized. Therefore, the use of the iron scrap can be expanded by employing the method according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows notionally the structure of an example of a reaction container for implementing the separation and collection | recovery method of the coexistence element which concerns on this invention.
FIG. 2 is a diagram conceptually showing a separation and recovery device for coexisting elements used in the present embodiment. FIG.
3 is a result of measuring a part of the surface on the recovery region side of the solid Ag phase after completion of the test of this example by X-ray diffraction (XRD).

Hereinafter, the separation / recovery method of the element (coexistence element) which coexists with iron in iron scrap which concerns on this invention is demonstrated in detail.

1. Separation and Recovery Principle

The separation and recovery method of coexisting elements in iron scrap using Ag in the present invention is characterized in that the molten Fe phase and the molten Ag phase made of a melt obtained by melting the iron scrap are separated into two liquid phases and have little solubility to each other and are not melted. That is, a property having a particularly low compatibility and a property of being difficult to react with oxygen because the molten Ag phase which is a medium phase are precious metals are used.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows notionally the structure of an example of a reaction container for implementing the separation and collection | recovery method of the coexistence element which concerns on this invention.

The molten Ag phase has a specific gravity higher than that of the molten Fe phase. Therefore, as a reaction vessel for carrying out the method according to the present invention, a structure in which a partition is provided in a form in which a molten Ag phase exists in the lower layer and penetrates into a part of the molten Ag phase as shown in FIG. 1 can be considered. In this structure, the molten Fe phase and the molten Ag phase contact each other in one region divided by a partition, and oxygen is supplied to the surface of the molten Ag in the other region. Hereinafter, the said one area | region is called "separation area", and the said other area | region is called "recovery area | region."

Since Fe and Ag have little solubility with each other, that is, their compatibility is particularly low, the molten Fe phase and the molten Ag phase are separated into two liquid phases in the separation region. Therefore, the coexisting elements in the iron scrap are divided into the molten Fe phase and the molten Ag phase separated into two liquid phases.

The coexisting element distributed in the molten Ag phase spreads over the partition to the recovery region, and reaches the surface vicinity of the molten Ag in the recovery region. Since oxygen is supplied to the surface of the molten Ag in the recovery region, the recovery region is in a strongly oxidizing atmosphere. For this reason, the coexisting element which reached the surface vicinity of molten Ag of a recovery area | region is oxidized rapidly. Here, molten Ag as a medium is difficult to oxidize because it is a noble metal. Therefore, the coexisting element is preferentially oxidized and becomes an oxide and removed from the molten Ag phase.

In this way, when the coexistence element in a molten Ag phase is oxidized and removed, the density | concentration of the coexistence element in the recovery region of a molten Ag phase will fall. This effect promotes diffusion of coexisting elements from the separation zone to the recovery zone. For this reason, the density | concentration of the coexisting element in a separation area also falls. Then, based on the distribution equilibrium of the coexistence elements between a molten Fe phase and a molten Ag phase, a coexistence element moves from a molten Fe phase to a molten Ag phase in a separation area. Even while this phase shift between the coexisting elements occurs, the concentration of coexisting elements based on oxidation removal is generated in the recovery region, so that the coexistent elements moved from the separation region into the molten Ag phase are diffused into the recovery region. Further, it is oxidized and removed in the strongly oxidizing atmosphere of the recovery region.

With this principle, the coexisting elements contained in the molten Fe phase made of the melt of the iron scrap are continuously reduced, and these coexisting elements are recovered as oxides on the molten Ag side.

2. Target Element

Since the element is separated and recovered on the basis of the above principle (hereinafter referred to as "the present principle"), the element separated and recovered in the present invention is an element that is more easily oxidized than Ag which is a medium. These elements include so-called tramp elements such as Cu, Ni, Cr, Sn, Zn, and useful rare metals such as W, Mo, Co, Ni, V, and Nb. In particular, elements (Cu and the like) which are less oxidized than iron are not removed by conventional oxidation refining, but are efficiently separated and recovered by the method of the present invention based on the present principles. That is, among the nonferrous metal elements contained in the iron scrap, when the target is an element that is more easily oxidized than Ag and harder than Fe, the benefits of the separation and recovery method of the present invention can be best enjoyed.

Of course, metals (e.g. REM such as Sm) which are more easily oxidized than iron, i.e., can also be removed by conventional oxidation refining, can be recovered in the recovery region by this principle. However, in order to efficiently recover such elements in the recovery region, it is preferable to make the atmosphere of the separation region into a non-oxidizing atmosphere so that conventional oxidation refining does not proceed in the separation region.

In addition, as will be described later, since an element having a thermodynamic affinity for Fe, such as C, Si, B, or P, does not easily move from the molten iron scrap to the molten Ag, the separation of the element efficiently by the present principle It is difficult.

3. Atmosphere of separation zone

The atmosphere in the separation region where the molten Fe phase and the molten Ag phase is in contact is preferably a non-oxidizing atmosphere.

Since the coexistence element is transferred from the molten Fe phase to the molten Ag phase by using the distribution of elements between the molten Fe phase and the molten Ag phase, the target element of the separation / recovery method based on the present principle is dissolved in the molten Fe phase. To be done.

When the oxygen partial pressure in the atmosphere of the separation region, that is, in the vicinity of the interface between the molten Fe phase and the molten Ag phase is high, the element dissolved in the molten Fe phase may be an oxide. Thus, when it becomes an oxide in a molten Fe phase, it becomes difficult to move to a molten Ag phase through the interface between a molten Fe phase and a molten Ag phase. For this reason, such an element becomes difficult to recover in a recovery area.

On the other hand, when the atmosphere in the separation region where the molten Fe phase and the molten Ag phase is in contact with each other is a non-oxidizing atmosphere, there is a low possibility that the element dissolved in the molten Fe phase becomes an oxide. For this reason, the situation which becomes difficult to recover the element which is easy to oxidize in a recovery area | region is hard to arise.

4. Composition of melt of iron scrap

As described above, when the melt of the iron scrap is a molten Fe phase, it is realized that the molten Ag phase and the two-liquid phase are separated. However, as described below, the melt of the iron scrap is preferably a molten Fe-C phase. It is particularly preferable that C contained in the Fe—C phase is saturated and dissolved.

When separating into two liquid phases by Fe-Ag system which does not contain carbon, although it depends on the kind and concentration of coexisting elements, the temperature near iron melting point, ie, about 1800K, is needed. However, increasing the temperature of the whole system increases the solubility of Ag in the molten Fe phase. Therefore, the Ag concentration in the iron scrap after the separation and recovery method according to the present invention tends to be relatively high as compared with the case where the temperature of the entire system is not increased. This means that Ag, which is a medium after the implementation of the present invention, decreases relatively much, resulting in an increase in process loss.

On the other hand, if a carbon source is present when melting the iron scrap, since C acts on thermodynamic affinity with Fe, the melt of the iron scrap becomes a molten Fe-C phase from the molten Fe phase. For this reason, although melting | fusing point of a melt depends on the kind and concentration of a coexisting element, it falls to about 1500K or less, and two-liquid phase separation at relatively low temperature is attained. It is as mentioned above that this leads to the improvement of the quality of iron scrap after a process (improvement of iron purity in iron scrap), and the process loss (reduction of the amount of loss of medium Ag).

In addition, the inclusion of C further reduces the solubility of Ag in the melt of the iron scrap. For this reason, beyond the melting | fusing point only, the quality improvement of the iron scrap after a process, and the fall of process loss are brought about.

Moreover, the activity coefficient of the coexisting element in a molten Fe-C phase becomes large. For this reason, in the distribution between the molten Fe-C phase and the molten Ag phase of the coexisting elements, it is thermodynamically expected to increase the concentration of the coexisting elements distributed in the molten Ag phase, that is, from the molten Fe-C phase into the molten Ag phase. Movement of co-existing elements is accelerated.

In addition, by containing C, reaction of Fe and oxygen in the melt of an iron scrap is suppressed. For this reason, the amount of iron recovered from the iron scrap increases.

Reactions corresponding to the formulas (2) to (4) in the case where the molten iron scrap is made into molten Fe-C phase are as shown in the following formulas (2) to (4) '.

Table 1 shows a calculation result of the reduced threshold of the element concentration in the co-P = _O2 molten Fe-C phase when in contact with the molten Ag under 1atm control (C concentration is 4.4% by mass).

Table 1 has shown that the density | concentration in the molten Fe-C phase of tramp elements, such as Cu and Ni, can be reduced. Table 1 also shows that metallic elements such as W, Mo, Co, V, and Nb may have an extremely small amount of residual metal in the molten Fe-C phase. Thus, based on this principle, Table 1 has shown that the coexisting element can be efficiently extracted from a molten Fe-C phase, and can be isolate | separated and recovered.

Although C concentration N _C (unit: mass%) in a molten Fe-C phase is not specifically limited, Since a saturated melt mole fraction is determined according to the temperature of a molten Fe-C phase, it becomes the range shown by following formula (1).

N _C ≤10 ^{12.728 / T + 0.7271 × log T -3.049} (1)

Here, T is the temperature of the melt of the iron scrap and satisfies 1426K <T <1873K.

When the temperature T of the iron scrap melt is 1426K or less, it becomes difficult for the Fe-C phase to exist as a liquid phase. For this reason, it becomes practically impossible to implement the separation and collection method based on the present principle.

In the case where the temperature T of the iron scrap melt is 1873 K or more, the energy input for performing the separation and recovery method based on the present principle becomes excessive. For this reason, the benefit of implementing this method is substantially lost.

As the C concentration N _C is higher, Ag is less likely to move on the molten Fe-C phase, and coexisting elements are more likely to move on the molten Ag phase side. Therefore, C is preferably saturated in the molten Fe-C phase. In addition, when the C concentration N _C is high, even if oxygen supplied from the recovery region reaches the separation region due to diffusion or the like, the C contained in the molten Fe-C phase in contact with the molten Ag phase is rapidly increased. Is removed out of the system. For this reason, maintaining the separation region in a non-oxidizing atmosphere is realized stably and easily. The C concentration N _C at which the benefit of containing carbon is clear varies depending on the composition of the iron scrap melt.

The method of supplying C to the melt of the iron scrap is not particularly limited. As shown in FIG. 1, carbon sources, such as coal, may be melted in the state which coexisted with iron scrap. As shown in FIG. 2, it is preferable to make the crucible which melts an iron scrap into a graphite crucible. While carbon is supplied from the graphite crucible, it is easily realized that the atmosphere near the melt of the iron scrap is made into a non-oxidizing atmosphere.

Similarly to C, in the case where an element having a thermodynamic affinity with Fe, for example, B, Si, P, or the like is contained in the melt of the iron scrap, the same effects as those obtained in the case of C can be obtained. If this is explained from another viewpoint, when B, Si, and P are contained in iron scrap as coexistence elements, it is difficult to separate and collect these elements by this principle.

5. Materials on Media

In the present invention, a molten Ag phase is used as a moving medium phase of coexisting elements contained in iron scrap. The molten Ag phase is a medium phase interposed between the melt of the iron scrap and the gas phase containing oxygen, and hardly reacts with oxygen itself. By interposing the molten Ag phase in this manner, it is suppressed that molten iron in the melt of the iron scrap directly causes an oxidation reaction. Coexistent elements such as Cu, which have moved from the molten iron scrap to the recovery region through the molten Ag phase as a medium, are oxidized in the oxidizing atmosphere of the recovery region and become insoluble in the molten Ag phase and can be recovered. For this reason, the molten Ag phase can be used continuously.

In addition, noble metals other than Ag can also be used as a medium in principle, but noble metals other than Ag (Au, Pt, etc.) are extremely expensive, and therefore materials on a medium for moving coexisting elements, even if they are continuously available, are available. Using them as is not realistic. In addition, since Cu often becomes a recovery target element, it is preferable not to use Cu as a material on a medium.

Pb can be used only from the viewpoint of distributing and separating the coexisting elements contained in the iron scrap in the separation region, but the medium itself volatilizes or oxidizes due to oxidation refining in the recovery region. In addition, Pb is a metal with a large environmental load. For this reason, Pb is not used as a medium in the separation and recovery method according to the present invention.

6. When the separation area and the recovery area are integrated

In the above description, in order to facilitate understanding of the present principle, the case where the separation area and the recovery area are divided by partitions is described, but this configuration is not essential to the present principle.

The entire atmosphere may be an oxidizing atmosphere, and the molten iron scrap may be brought into contact with the molten Ag. In this case, elements that are more easily oxidized than Fe and Fe are removed from the molten iron scrap by oxidation proceeding on the surface of the molten iron scrap. Moreover, the element which is harder to oxidize than Fe and which is more easily oxidized than Ag, is oxidized on the surface of molten Ag, and as a result, it is removed from the molten iron scrap.

In such a configuration, when the melt of the iron scrap contains C and is in the molten Fe-C phase, when it does not contain C, among the elements oxidized on the surface of the melt of the iron scrap, the oxide is more oxidized than C in the atmosphere. The element which is hard to be able to move to the molten Ag from the melt of an iron scrap. As a result, it becomes oxidized on the surface of molten Ag. Of course, it is as mentioned above that the separation and collection | recovery method which concerns on this invention are performed more efficiently. In addition, oxidation of molten iron in the melt of the iron scrap is suppressed by the content C. For this reason, recovering the Fe-C phase in which content of the coexisting element declined with higher yield is implement | achieved.

<Examples>

Although an Example is given to the following and this invention is demonstrated to it further more concretely, this invention is not restrict | limited by these Examples.

The Example in which Cu contained as a co-existing element in Fe was oxidized and removed using Ag as a medium is shown.

As shown in Fig. 2, a notched alumina tube (outer diameter 17mm, inner diameter 12mm, height 55mm) is installed in the alumina crucible (outer diameter 30mm, inner diameter 24mm, height 50mm), and the Cu concentration in the alumina tube is 1.8% by mass. Approximately 30 g of the total Ag and Cu prepared is added, and Ar (purity 99.99%) is preliminarily dissolved in an atmosphere formed by supplying 100 cm ³ / min (standard condition conversion) from the gas injection tube, and then the Ag- crucible and the inside of the alumina tube are subjected to Ag- It cooled by filling with Cu alloy.

Moreover, the reason which Cu contained in Ag which is a medium beforehand is as follows.

When the molten phase containing only Ag is brought into contact with the molten Fe phase containing Cu, the following two phenomena occur.

(1) Cu moves from the molten Fe phase to the molten Ag phase until it reaches the Cu concentration determined by the distribution of the molten Fe phase and the molten Ag phase, and therefore, the Cu concentration in the molten Fe phase decreases (based only on distribution). Reduced Cu concentration).

(2) When oxygen is injected onto the molten Ag, the Cu on the molten Ag phase is oxidized and removed, and the Cu concentration in the molten Fe phase is further reduced (the Cu concentration based on the oxidation removal) due to the effect.

As described above, since the concentration of Cu in the molten Fe phase decreases due to the development of both distribution and oxidation removal, the development of both cannot be independently evaluated.

In contrast, on the other hand, when the molten Fe-containing Cu phase is brought into contact with the molten Fe-Cu phase containing Cu at a concentration determined in advance by the distribution of the molten Fe phase and the molten Ag phase, it is based only on the distribution shown in the above (1). The decrease in Cu concentration in the molten Fe phase does not occur. For this reason, only the Cu concentration reduction based on the oxidation removal shown in (2) occurs, and it becomes possible to confirm the principle of the present invention more clearly.

As described above, after filling the alumina crucible and the inside of the alumina tube with Ag-Cu alloy, 4 g of pre-dissolved Fe-4 mass% Cu-C (saturated) alloy is placed on the Ag-Cu alloy in the alumina tube, and the Fe The surroundings of the -Cu-C alloys were covered with a graphite tube and a graphite lid.

The graphite tube and the graphite lid keep the periphery of the Fe—Cu—C alloy in a reducing atmosphere and play a role of supplying carbon to Fe.

In this state, the temperature was set to 1523 K, and Ar was kept for 1 hour in an atmosphere supplied from the gas injection tube at 100 cm ³ / min (standard state conversion), and then the supply from the gas injection tube was O ₂ (purity 99.5%). Was converted into 100 cm ³ / min (standard state conversion), and the resultant was cooled for 3 hours or 7 hours.

The Cu, Ag and C concentrations in the solid Fe phase and the Cu concentration in the solid Ag phase of the sample obtained by air cooling to room temperature were analyzed. Table 2 shows the results.

Cu in Fe decreases at the initial concentration and becomes close to the Cu concentration (0.26 mass%) obtained by the thermodynamic equilibrium calculation. By using the separation and recovery method according to the present invention, Cu is calculated from the Fe phase by thermodynamic equilibrium calculation. It was confirmed that it can selectively oxidize and remove to an expected concentration.

In addition, when a part of the surface of the recovery region side on the solid Ag phase after completion of the test was measured by X-ray diffraction (XRD), a peak of Cu ₂ O was observed as shown in FIG. 3, and it was confirmed that Cu was oxidized and removed. It became.

Claims (7)

As a method for separating and recovering elements coexisting in iron scrap,
Melting the iron scrap,
Transferring the elements coexisting in the iron scrap to the molten Ag by bringing the molten Ag of the obtained iron scrap into contact with the molten Ag, and
Separation and recovery method comprising the step of oxidizing and removing the element transferred to the molten Ag from the molten Ag. The method according to claim 1,
A separation and recovery method for melting iron scrap and contacting the molten iron scrap with molten Ag in a non-oxidizing atmosphere. The method according to claim 1,
Separation and recovery method in which the molten iron scrap contains C, and the concentration N _C (unit: mass%) satisfies the following formula (1):
N _C ≤10 ^{12.728 / T + 0.7271 × log T -3.049} (1)
Here, T is the temperature of the melt of the iron scrap and satisfies 1426K <T <1873K. The method according to claim 3,
A separation and recovery method of obtaining a melt of the iron scrap containing C by melting the iron scrap together with a carbon source. The method according to claim 3,
A separation and recovery method in which iron scrap is melted and the molten iron scrap melt and molten Ag are contacted in a graphite crucible, where C is dissolved in the molten iron scrap. The method according to claim 1,
Separation and recovery method, wherein the element to be separated and recovered includes a tramp element. The method according to claim 1,
Separation and recovery method, wherein the element to be separated and recovered includes one or two or more selected from the group consisting of W, Mo, Co, V and Nb.

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