Refining method and refining apparatus

Abstract

A refining method comprising: a first step for obtaining a molten copper containing nickel as an impurity; a second step for bringing slag containing diphosphorus pentoxide into contact with the molten copper; and a third step for removing the slag containing the nickel from the molten copper.

Description

Refining method and refining apparatus

[0001] The present disclosure relates to a refining method and a refining apparatus.

[0002] Patent Document 1 discloses a method for refining copper, in which a molten copper containing one or more metal elements selected from the group consisting of Sn, Pb, Ni, and Zn is brought into contact with SiO ２ and slag containing FeO, and the above metal elements are removed from the molten copper together with the slag.

[0003] Japanese Unexamined Patent Application Publication No. 2005-42162

[0004] The refining method of the present disclosure comprises: a first step of obtaining a molten copper containing nickel as an impurity; a second step of bringing the molten copper into contact with slag containing diphosphorus pentoxide; and a third step of removing the slag containing nickel from the molten copper.

[0005] FIG. 1 is a schematic diagram illustrating an example of the refining method according to the embodiment. FIG. 2 is a graph showing the change over time in the concentration of nickel in the molten copper measured in Test Example 1. FIG. 3 is a graph showing the relationship between the concentration of phosphorus in the molten copper and the concentration of oxygen in the molten copper measured in Test Example 2. FIG. 4 is an enlarged partial graph of the graph in FIG. 3.

[0006] [Problem to be Solved by the Present Disclosure] In the copper refining method described in Patent Document 1, nickel (Ni) and lead (Pb) are less likely to be reduced from molten copper than tin (Sn) and zinc (Zn).

[0007] An object of the present disclosure is to provide a refining method capable of easily reducing nickel, which is an impurity, from molten copper.

[0008] [Effect of the Present Disclosure] The refining method of the present disclosure can easily reduce nickel, which is an impurity, from molten copper.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (1) A refining method according to the embodiment of the present disclosure comprises a first step of obtaining molten copper containing nickel as an impurity, a second step of contacting the molten copper with a slag containing phosphorus pentoxide, and a third step of removing the nickel-containing slag from the molten copper.

[0011] When molten copper containing nickel as an impurity is brought into contact with a slag containing phosphorus pentoxide, the nickel is easily incorporated into the slag. By removing this nickel-containing slag from the molten copper, the amount of nickel in the molten copper can be easily reduced.

[0012] (2) In the refining method of (1) above, in the second step, the slag may be brought into contact with the molten metal such that the ratio of the mass of phosphorus pentoxide to the mass of nickel in the molten metal is 1.5 or more and 700 or less.

[0013] If the above mass ratio is 1.5 or higher, nickel is more easily incorporated into the slag. The higher the above mass ratio, the greater the nickel reduction effect, but if the above mass ratio is too high, copper is also more easily incorporated into the slag. If the above mass ratio is 700 or lower, nickel can be reduced from the molten copper, and copper loss can also be reduced.

[0014] (3) In the refining method of (1) or (2) above, in the second step, an alloy containing copper and phosphorus and oxygen may be supplied to the molten metal.

[0015] When an alloy containing copper and phosphorus and oxygen are supplied to the molten metal, the alloy containing copper and phosphorus is oxidized in the molten metal to produce phosphorus pentoxide. The production of phosphorus pentoxide from the alloy containing copper and phosphorus results in a higher nickel reduction effect compared to supplying phosphorus pentoxide to the molten metal. When oxygen is supplied to the molten metal, nickel oxide is produced. Nickel oxide is a basic oxide, while phosphorus pentoxide is an acidic oxide. Nickel oxide and phosphorus pentoxide are highly reactive. Therefore, nickel oxide is more easily incorporated into the slag by reacting with phosphorus pentoxide, improving the nickel reduction effect.

[0016] (4) In the refining method of (3) above, in the second step, the slag may be brought into contact with the molten metal such that the phosphorus concentration in the molten metal is 500 ppm by mass or less and the oxygen concentration in the molten metal is 300 ppm by mass or more.

[0017] If the phosphorus concentration in the molten metal is too high, nickel oxide is less likely to be formed, and the nickel reduction effect tends to decrease. If the phosphorus concentration in the molten metal is 500 ppm by mass or less, and the oxygen concentration in the molten metal is 300 ppm by mass or more, both nickel oxide and phosphorus pentoxide are easily formed, resulting in a high nickel reduction effect.

[0018] (5) In the refining method of (3) or (4) above, in the second step, air may be supplied to the molten metal by bubbling.

[0019] By bubbling air into the molten metal, the molten metal can be stirred, making it easier to generate both nickel oxide and phosphorus pentoxide.

[0020] (6) In the refining method of (3) or (4) above, copper oxide or surface-oxidized copper may be supplied to the molten metal in the second step.

[0021] By supplying copper oxide or surface-oxidized copper to the molten metal, both nickel oxide and phosphorus pentoxide can be produced, and even if some of the molten copper is incorporated into the slag, the loss of that copper can be compensated for.

[0022] (7) In any of the refining methods described in (1) to (6) above, the material of the furnace for storing the molten metal may include at least one of aluminum oxide, magnesium oxide, chromium oxide, and silicon oxide.

[0023] Depending on the furnace material, the oxygen supplied to the molten metal may react with the furnace's constituent materials. If the furnace is made of the materials listed above, the oxygen supplied to the molten metal inside the furnace is less likely to react with the furnace's constituent materials, and both nickel oxide and phosphorus pentoxide are more likely to be produced.

[0024] (8) A refining apparatus according to the embodiment of the present disclosure comprises a furnace for storing molten copper and a supply unit for supplying slag into the molten copper. The supply unit comprises a first supply unit for supplying oxygen and a second supply unit for supplying an alloy containing copper and phosphorus.

[0025] When oxygen is supplied to the molten metal by the first supply unit and an alloy containing copper and phosphorus is supplied to the molten metal by the second supply unit, the alloy containing copper and phosphorus is oxidized in the molten metal to produce phosphorus pentoxide. The production of phosphorus pentoxide from the alloy containing copper and phosphorus results in a higher nickel reduction effect compared to supplying phosphorus pentoxide to the molten metal. When oxygen is supplied to the molten metal, nickel oxide is produced. Nickel oxide is a basic oxide, and phosphorus pentoxide is an acidic oxide. Nickel oxide and phosphorus pentoxide are highly reactive. Therefore, nickel oxide is more easily incorporated into the slag by reacting with phosphorus pentoxide, improving the nickel reduction effect.

[0026] (9) In the refining apparatus described in (8) above, the material of the furnace may include at least one of aluminum oxide, magnesium oxide, chromium oxide, and silicon oxide.

[0027] Depending on the furnace material, the oxygen supplied to the molten metal may react with the furnace's constituent materials. If the furnace is made of the materials listed above, the oxygen supplied to the molten metal inside the furnace is less likely to react with the furnace's constituent materials, and both nickel oxide and phosphorus pentoxide are more likely to be produced.

[0028] [Details of Embodiments of the Disclosure] Specific examples of the refining method and refining apparatus of the Disclosure will be described with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. In each drawing, some components may be exaggerated or simplified for illustrative purposes. The dimensional ratios of parts in the drawings may also differ from those of the actual components. The present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included.

[0029] <Overview> The refining method and refining apparatus of the embodiment will be described with reference to Figure 1. In the refining method of the embodiment, as shown in the middle diagram of Figure 1, slag 3 is brought into contact with molten metal 2, impurities in the molten metal 2 are incorporated into the slag 3, and as shown in the lower diagram of Figure 1, the impurities are removed from the molten metal 2 together with the slag 3, thereby reducing the concentration of impurities in the molten metal 2. The molten metal 2 is molten copper and contains nickel 4 as an impurity.

[0030] The refining method of this embodiment comprises a first step of obtaining molten copper 2 containing nickel 4 as an impurity, a second step of contacting slag 3 with the molten metal 2, and a third step of removing the slag 3 containing nickel 4 from the molten metal 2. One of the features of the refining method of this embodiment is that the slag 3 contains phosphorus pentoxide 7. In this embodiment, Cu-P alloy 5 and oxygen 6 are supplied to the molten metal 2, and phosphorus pentoxide 7 is produced in the molten metal 2. Cu-P alloy 5 is an alloy containing copper and phosphorus. When oxygen 6 is supplied to the molten metal 2, nickel oxide 8 and copper oxide 9 are produced in the molten metal 2.

[0031] In each diagram, nickel 4, Cu-P alloy 5, oxygen 6, phosphorus pentoxide 7, nickel oxide 8, and copper oxide 9 are shown as circles for clarity.

[0032] <Smelting Apparatus> The smelting apparatus 1 comprises a furnace 11 and a supply unit 12. The furnace 11 stores molten copper 2. The material of the furnace 11 includes, for example, at least one of aluminum oxide, magnesium oxide, chromium oxide, and silicon oxide. Depending on the material of the furnace 11, the oxygen 6 supplied to the molten metal 2 may react with the constituent material of the furnace 11. When the oxygen 6 supplied to the molten metal 2 reacts with the constituent material of the furnace 11, the amount of oxygen 6 that reacts with the Cu-P alloy 5 or nickel 4 decreases, making it difficult to produce phosphorus pentoxide 7 and nickel oxide 8. When the furnace 11 is formed of the materials listed above, the oxygen 6 supplied to the molten metal 2 does not react with the constituent material of the furnace 11, and both phosphorus pentoxide 7 and nickel oxide 8 are easily produced.

[0033] The supply unit 12 in this example comprises a first supply unit 13 and a second supply unit 14. The first supply unit 13 supplies oxygen 6. The first supply unit 13 comprises, for example, piping that is resistant to molten metal 2. The material of the piping is, for example, aluminum oxide, magnesium oxide, chromium oxide, silicon oxide, silicon carbide, or stainless steel. The tip of the piping is immersed in the molten metal 2. The piping is arranged, for example, to supply oxygen 6 below the molten metal 2. The first supply unit 13, consisting of piping, is configured, for example, to supply air into the molten metal 2 by bubbling. The second supply unit 14 supplies Cu-P alloy 5. The Cu-P alloy 5 is supplied, for example, in shot form or plate form. The second supply unit 14 is, for example, a bag containing the Cu-P alloy 5. The Cu-P alloy 5, contained in the bag, is poured into the molten metal 2 from above, for example, by a forklift.

[0034] The first supply unit 13 may be a bag containing copper oxide. The supply of copper oxide supplies oxygen to the molten metal 2. The copper oxide, contained in the bag, is poured into the molten metal 2 from above, for example, by a forklift. In this case, the first supply unit 13 and the second supply unit 14 may be independent of each other, and the copper oxide and Cu-P alloy 5 may be poured into the molten metal 2 individually. The first supply unit 13 and the second supply unit 14 may constitute a single supply unit, and the copper oxide and Cu-P alloy 5 may be contained in the same bag, and the copper oxide and Cu-P alloy 5 may be poured into the molten metal 2 simultaneously. Surface-oxidized copper may be supplied instead of copper oxide. Both copper oxide and surface-oxidized copper may be supplied.

[0035] <Refining Method> In the first step, molten copper 2 containing nickel 4 as an impurity is obtained. Molten copper 2 may contain, for example, used copper material, i.e., copper scrap, in a melted state. Copper scrap may be included in at least a portion of the raw materials for molten copper 2, or all of the raw materials for molten copper 2 may be copper scrap. Copper scrap tends to contain a large amount of impurities such as nickel 4.

[0036] In the second step, as shown in the middle diagram of Figure 1, a slag 3 containing phosphorus pentoxide 7 is brought into contact with the molten metal 2. In the second step of this example, as shown in the upper diagram of Figure 1, oxygen 6 is supplied to the molten metal 2 by the first supply unit 13, and Cu-P alloy 5 is supplied to the molten metal 2 by the second supply unit 14. When Cu-P alloy 5 and oxygen 6 are supplied to the molten metal 2, the Cu-P alloy 5 is oxidized in the molten metal 2 to produce phosphorus pentoxide 7.

[0037] When oxygen 6 is supplied to the molten metal 2, nickel oxide 8 is produced. Nickel oxide 8 is a basic oxide, and phosphorus pentoxide 7 is an acidic oxide. Nickel oxide 8 and phosphorus pentoxide 7 are highly reactive. Therefore, nickel oxide 8 reacts with phosphorus pentoxide 7 and is incorporated into the slag 3.

[0038] When oxygen 6 is supplied to the molten metal 2, copper oxide 9 is also produced. Copper oxide 9 is produced from the copper or Cu-P alloy 5 in the molten metal 2. Copper oxide 9 is also incorporated into the slag 3. As shown in the lower part of Figure 1, the slag 3 contains phosphorus pentoxide 7, nickel oxide 8, and copper oxide 9.

[0039] In the second step, oxygen 6 is supplied, for example, by bubbling air into the molten metal 2. By bubbling air into the molten metal 2, the molten metal 2 can be stirred, making it easier to generate both phosphorus pentoxide 7 and nickel oxide 8. The air used for bubbling may also be oxygen-enriched air. In the second step, for example, with oxygen 6 supplied by bubbling air into the molten metal 2, the Cu-P alloy 5 is supplied.

[0040] In the second step, for example, the molten metal 2 is brought into contact with the slag 3 such that the ratio of the mass of diphosphorus pentoxide 7 to the mass of nickel 4 in the molten metal 2 is 1.5 or more and 700 or less. When the mass ratio is 1.5 or more, nickel oxide 8 is easily incorporated into the slag 3, and the removal effect of nickel 4 is high. The higher the mass ratio, the higher the effect of reducing nickel 4. However, if the mass ratio is too high, copper oxide 9 generated from copper in the molten metal 2 is easily incorporated into the slag 3. When the mass ratio is 700 or less, nickel 4 can be reduced from the molten metal 2, and the loss of copper from the molten metal 2 can be reduced. The ratio of the mass of diphosphorus pentoxide 7 to the mass of nickel 4 in the molten metal 2 may be 2.0 or more and 650 or less, 3.0 or more and 600 or less, or 4.0 or more and 550 or less.

[0041] In the second step, for example, the molten metal 2 is brought into contact with the slag 3 such that the concentration of phosphorus in the molten metal 2 is 500 ppm by mass or less, and the concentration of oxygen 6 in the molten metal 2 is 300 ppm by mass or more. If the concentration of phosphorus in the molten metal 2 is too high, oxygen 6 will be consumed for the generation of diphosphorus pentoxide 7, making it difficult to generate nickel oxide 8, which may reduce the effect of reducing nickel 4. When the concentration of phosphorus in the molten metal 2 is 500 ppm by mass or less and the concentration of oxygen 6 in the molten metal 2 is 300 ppm by mass or more, both diphosphorus pentoxide 7 and nickel oxide 8 are easily generated, and the effect of reducing nickel 4 is high.

[0042] The concentration of phosphorus in the molten metal 2 is, for example, 0.1 ppm by mass or more. The concentration of phosphorus in the molten metal 2 is, for example, 0.1 ppm by mass or more and 500 ppm by mass or less. When the concentration of phosphorus in the molten metal 2 falls within the above range, both diphosphorus pentoxide 7 and nickel oxide 8 are easily generated. The concentration of phosphorus in the molten metal 2 may be 0.5 ppm by mass or more and 450 ppm by mass or less, or 1.0 ppm by mass or more and 400 ppm by mass or less.

[0043] The concentration of oxygen 6 in the molten metal 2 is, for example, 50000 ppm by mass or less. If the concentration of oxygen 6 in the molten metal 2 is too high, the copper in the molten metal 2 becomes copper oxide 9 and is easily incorporated into the slag 3. If the concentration of oxygen 6 in the molten metal 2 is 50000 ppm by mass or less, the loss of copper from the molten metal 2 can be reduced. The concentration of oxygen 6 in the molten metal 2 is, for example, 300 ppm by mass or more and 50000 ppm by mass or less. The concentration of oxygen 6 in the molten metal 2 may be 500 ppm by mass or more and 35000 ppm by mass or less, or 700 ppm by mass or more and 20000 ppm by mass or less.

[0044] In the second step, diphosphorus pentoxide 7 may be supplied into the molten metal 2 instead of the Cu-P alloy 5. In the second step, both the Cu-P alloy 5 and diphosphorus pentoxide 7 may be supplied into the molten metal 2. However, since the sublimation point of diphosphorus pentoxide 7 is 360°C, when diphosphorus pentoxide 7 is supplied into the molten metal 2, the diphosphorus pentoxide 7 may sublime before nickel oxide 8 is incorporated into the slag 3. Therefore, compared with supplying diphosphorus pentoxide 7 into the molten metal 2, supplying the Cu-P alloy 5 and oxygen 6 to generate diphosphorus pentoxide 7 in the molten metal 2 allows nickel oxide 8 to be more easily incorporated into the slag 3 before diphosphorus pentoxide 7 sublimes, resulting in a higher nickel reduction effect.

[0045] In the second step, instead of supplying oxygen 6 by bubbling air into the molten metal 2, copper oxide or copper with an oxidized surface may be supplied into the molten metal 2. In the second step, copper oxide or copper with an oxidized surface may be supplied into the molten metal 2 while supplying oxygen 6 by bubbling air into the molten metal 2. By supplying copper oxide or copper with an oxidized surface into the molten metal 2, both nickel oxide 8 and diphosphorus pentoxide 7 can be generated, and even if copper from the molten metal 2 is incorporated into the slag 3, the loss of the copper can be compensated.

[0046] In the second step, copper oxide and copper phosphide may be supplied into the molten metal 2. Diphosphorus pentoxide is generated by the reaction between the copper oxide and copper phosphide supplied into the molten metal 2.

[0047] In the third step, as shown in the lower diagram of Figure 1, the slag 3 containing nickel 4 is removed from the molten metal 2. The slag 3, which contains phosphorus pentoxide 7, nickel oxide 8, and copper oxide 9, floats to the surface of the molten metal 2. By removing this floating slag 3, the amount of nickel 4 in the molten metal 2 can be reduced.

[0048] [Test Example 1] In Test Example 1, the concentration of nickel in molten copper containing nickel as an impurity was measured over time when slag was brought into contact with the molten copper. The concentration of nickel in the molten copper was measured by ICP (Inductively Coupled Plasma) emission spectroscopy. In this example, test specimen A used slag containing phosphorus pentoxide and silicon dioxide (SiO ２ Measurements were taken for both specimen A and specimen B, which used slag containing iron oxide (FeO). The results are shown in Figure 2. In the graph shown in Figure 2, the horizontal axis represents time, and the vertical axis represents the concentration of nickel in the molten metal. In the graph shown in Figure 2, the results for specimen A are indicated by black circles, and the results for specimen B are indicated by black triangles.

[0049] In both test specimen A and test specimen B, the furnace is made of aluminum oxide.

[0050] <Test Specimen A> In Test Specimen A, an alloy containing copper and phosphorus (Cu-P alloy) was supplied to the molten metal while oxygen was being supplied by bubbling air into the molten metal, generating phosphorus pentoxide in the molten metal. At the start of the test, the nickel concentration in the molten metal was approximately 680 ppm. Air was blown into the molten metal at a flow rate of 300 cc / min. The oxygen concentration in the molten metal was gradually increased from the start of the test, and 87 g of Cu-P alloy was supplied to the molten metal at time A1. As shown in Figure 2, the nickel concentration in the molten metal decreased to below 200 ppm when the Cu-P alloy was supplied to the molten metal at time A1. It is thought that the nickel concentration in the molten metal decreased because nickel oxide was generated by supplying oxygen, phosphorus pentoxide was generated by further supplying Cu-P alloy, and the nickel oxide reacted with phosphorus pentoxide and was incorporated into the slag.

[0051] As shown in Figure 2, when the oxygen concentration in the molten metal was gradually increased after supplying the Cu-P alloy, the nickel concentration in the molten metal increased slightly. Therefore, 87g of Cu-P alloy was added to the molten metal at time A2. The addition of the Cu-P alloy slightly decreased the nickel concentration in the molten metal. However, this decrease was smaller than the decrease in nickel concentration in the molten metal caused by supplying the Cu-P alloy at time A1. The reason why the decrease in nickel concentration in the molten metal caused by supplying the Cu-P alloy at time A2 was small is thought to be because the phosphorus concentration in the molten metal became too high, and the oxygen was used to produce phosphorus pentoxide, making it difficult to produce nickel oxide.

[0052] In specimen A, the equilibrium Ni distribution ratio was 211 when the Cu-P alloy was supplied at time A1. The equilibrium Ni distribution ratio is an indicator of the ability to reduce nickel from the molten metal, and is the ratio of the nickel concentration in the slag to the nickel concentration in the molten metal. A higher equilibrium Ni distribution ratio indicates a higher ability to reduce nickel from the molten metal. The method for calculating the equilibrium Ni distribution ratio will be described later.

[0053] <Test Specimen B> In Test Specimen B, oxygen was supplied by bubbling air into the molten metal, and SiO ２ A slag containing FeO was supplied. The nickel concentration in the molten metal at the start of the test was approximately 970 ppm. Air was blown into the molten metal at a flow rate of 300 cc / min. The oxygen concentration in the molten metal was gradually increased from the start of the test, and 25 g of the above slag was supplied to the molten metal at time B1. As shown in Figure 2, the supply of the above slag to the molten metal at time B1 reduced the nickel concentration in the molten metal to below 750 ppm. The equilibrium Ni distribution ratio at this time was 23. 75 g of the above slag was added to the molten metal at time B2. Although the nickel concentration in the molten metal decreased with the addition of the above slag, it could not be reduced to below 400 ppm.

[0054] <Method for Calculating the Equilibrium Ni Distribution Ratio> The equilibrium Ni distribution ratio can be calculated using the following formula: L Ｎｉ =(1 / B)×{A×(β / α) １／ｎ -A'} The notation for the above formula is as follows: L Ｎｉis the equilibrium Ni distribution ratio. A is the weight of the molten metal at the start of refining. A' is the weight of the molten metal after a predetermined time has elapsed since the start of refining. B is the weight of the slag. In the above formula, the weight of the slag is the weight of the slag excluding nickel oxide and copper oxide. Although the slag contains nickel oxide and copper oxide, the weights of nickel oxide and copper oxide are ignored in the above formula. In specimen A, the weight of the slag in the above formula is the weight of phosphorus pentoxide. In specimen B, the weight of the slag in the above formula is SiO ２ This is the total weight of α and FeO. α is the nickel concentration in the molten metal after a predetermined time has elapsed since the start of refining. β is the nickel concentration in the molten metal at the start of refining. n is the number of times the slag generation, impurity absorption, and slag removal cycle is performed. The units for A, A', and B are kg. The units for α and β are ppm.

[0055] [Test Example 2] In Test Example 2, using Test Specimen A from Test Example 1, the ratio of the mass of phosphorus pentoxide to the mass of nickel in the molten metal was set to 1.5 or more and 700 or less. Then, test specimens were prepared with varying concentrations of phosphorus and oxygen in the molten metal, and the equilibrium Ni distribution ratio was determined. The phosphorus concentration in the molten metal can be measured by ICP emission spectrometry. The oxygen concentration in the molten metal can be measured by inert gas fusion-infrared absorption spectroscopy. The results are shown in Figures 3 and 4. The graph in Figure 4 shows an enlarged view of the region near the origin of the graph in Figure 3. In the graphs shown in Figures 3 and 4, the horizontal axis represents the phosphorus concentration in the molten metal, and the vertical axis represents the oxygen concentration in the molten metal. In Figures 3 and 4, test specimens with an equilibrium Ni distribution ratio of 23 or more are indicated by black circles, and test specimens with an equilibrium Ni distribution ratio of less than 23 are indicated by black triangles.

[0056] As shown in Figures 3 and 4, all test specimens with an equilibrium Ni distribution ratio of 23 or higher had a phosphorus concentration of 500 ppm by mass or less in the molten metal and an oxygen concentration of 300 ppm by mass or more. When the phosphorus concentration in the molten metal is 500 ppm by mass or less and the oxygen concentration in the molten metal is 300 ppm by mass or more, both nickel oxide and phosphorus pentoxide are easily formed. It is thought that the nickel oxide reacted with phosphorus pentoxide and was incorporated into the slag, increasing the nickel concentration in the slag and decreasing the nickel concentration in the molten metal.

[0057] [Test Example 3] In Test Example 3, the oxygen concentration in the molten metal, the phosphorus concentration in the molten metal, and the equilibrium Ni distribution ratio were measured in Test Specimen A from Test Example 1, by changing the material of the furnace in which the molten metal was stored. The results are shown in Table 1. In this example, Test Specimen α, in which the furnace was made of aluminum oxide, and Test Specimens β and γ, in which the furnace was made of graphite were used. In Table 1, aluminum oxide is written as "alumina".

[0058] In this example, the oxygen concentration in the molten metal was measured at the start of the test and at a predetermined time after the Cu-P alloy was added. The phosphorus concentration in the molten metal was measured at a predetermined time after the Cu-P alloy was added. The phosphorus concentration in the molten metal at the start of the test is an estimated value. In Table 1, the value at the start of the test is labeled as the initial value, and the value at a predetermined time after the Cu-P alloy was added is labeled as the equilibrium value.

[0059]

[0060] As shown in Table 1, in test specimen α, where the furnace is made of aluminum oxide, both the oxygen concentration and the phosphorus concentration in the molten metal decreased after the addition of the Cu-P alloy, and the equilibrium Ni distribution ratio was 51. Since the furnace is made of aluminum oxide, it is thought that the oxygen supplied to the molten metal was spent on reacting with the Cu-P alloy or nickel without reacting with the furnace's constituent materials. In other words, in test specimen α, both nickel oxide and phosphorus pentoxide were easily produced, and it is thought that the nickel oxide reacted with phosphorus pentoxide and was incorporated into the slag, increasing the nickel concentration in the slag and decreasing the nickel concentration in the molten metal.

[0061] In specimens β and γ, where the furnace was made of graphite, the oxygen concentration in the molten metal decreased after the addition of the Cu-P alloy, but the phosphorus concentration in the molten metal did not decrease significantly, and the equilibrium Ni distribution ratio was less than 23. Because the furnace was made of graphite, the oxygen supplied to the molten metal readily reacted with the furnace's constituent materials and was likely spent more on reactions with the furnace than with the Cu-P alloy or nickel. Therefore, in specimens β and γ, where the furnace was made of graphite, the equilibrium Ni distribution ratio was low, less than 23.

[0062] 1. Refining apparatus 11. Furnace 12. Supply unit 13. First supply unit 14. Second supply unit 2. Molten metal 3. Slag 4. Nickel 5. Cu-P alloy 6. Oxygen 7. Phosphorus pentoxide 8. Nickel oxide 9. Copper oxide

Claims

1. A refining method comprising: a first step of obtaining molten copper containing nickel as an impurity; a second step of contacting the molten copper with a slag containing phosphorus pentoxide; and a third step of removing the nickel-containing slag from the molten copper.

2. The refining method according to claim 1, wherein in the second step, the slag is brought into contact with the molten metal such that the ratio of the mass of phosphorus pentoxide to the mass of nickel in the molten metal is 1.5 or more and 700 or less.

3. The refining method according to claim 1 or claim 2, wherein in the second step, an alloy containing copper and phosphorus and oxygen are supplied to the molten metal.

4. The refining method according to claim 3, wherein in the second step, the slag is brought into contact with the molten metal such that the phosphorus concentration in the molten metal is 500 ppm by mass or less and the oxygen concentration in the molten metal is 300 ppm by mass or more.

5. The refining method according to claim 3 or claim 4, wherein in the second step, air is supplied to the molten metal by bubbling.

6. The refining method according to claim 3 or claim 4, wherein in the second step, copper oxide or surface-oxidized copper is supplied to the molten metal.

7. The refining method according to any one of claims 1 to 6, wherein the material of the furnace for storing the molten metal includes at least one of aluminum oxide, magnesium oxide, chromium oxide, and silicon oxide.

8. A refining apparatus comprising a furnace for storing molten copper, and a supply unit for supplying slag into the molten copper, wherein the supply unit comprises a first supply unit for supplying oxygen and a second supply unit for supplying an alloy containing copper and phosphorus.

9. The refining apparatus according to claim 8, wherein the material of the furnace includes at least one of aluminum oxide, magnesium oxide, chromium oxide, and silicon oxide.

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