WO2020218237A1 - Dross generation suppression method, metal refinement method, and metal refinement apparatus - Google Patents

Abstract

This dross generation suppression method involves: setting an environmental atmosphere, in which a metal-containing object is placed, to a condition of having a water content less than that of the air environment of the periphery of the environmental atmosphere; and heating and melting the metal-containing object.

Description

Dross control method, metal refining method and metal refining equipment

The present invention relates to a method for suppressing the generation of dross, a method for refining a metal, and a metal refining apparatus. The present application claims priority based on Japanese Patent Application No. 2019-08216 filed in Japan on April 23, 2019, the contents of which are incorporated herein by reference.

In the metal production process, heat melting and molten metal treatment are performed. When performing the plating treatment, a plating bath in which the metal is melted is used, and when the metal is joined, the metal is often melted. Dross occurs mainly at the contact interface with the atmosphere in the melt obtained by such a melting treatment. The main component of dross is a metal oxide. The molten metal oxidizes as much as a few percent of the melted amount to become dross (oxide). Dross reduces the efficiency of metal recovery and has a large environmental load. If dross intervenes in the product, it may cause a malfunction. For example, Non-Patent Document 1 describes a method for efficiently separating a metal from dross.

For example, Non-Patent Document 1 describes a method for treating dross, and does not describe how to reduce dross fundamentally. In principle, if oxygen, which is an oxidant, is completely blocked, the generation of dross can be suppressed, but it is not realistic in terms of technology and cost.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for suppressing the generation of dross and a method for refining a metal, which can easily suppress the generation of dross.

The present inventors have found that if water can be reduced even in the presence of oxygen, the occurrence of dross can be dramatically suppressed. That is, the present invention provides the following means for solving the above problems.

(1) The method for suppressing the generation of dross according to the first aspect is to heat and melt the metal-containing material under the condition that the environmental atmosphere in which the metal-containing material is arranged has less moisture than the atmospheric environment surrounding the environmental atmosphere. ..

(2) In the method for suppressing the generation of dross according to the above aspect, the metal-containing material may be heated and melted while controlling the water content in the environmental atmosphere.

(3) In the method for suppressing the generation of dross according to the above aspect, the water content may be controlled so that the water content does not increase.

(4) In the method for suppressing the generation of dross according to the above aspect, the amount of water in the environmental atmosphere at the time of heating and melting may be 2000 ppm or less.

(5) In the method for suppressing the generation of dross according to the above embodiment, the metal-containing substance is a simple substance of aluminum or a group consisting of magnesium, zinc, lithium, potassium, sodium, calcium, iron, titanium, cerium, thorium and beryllium. It may contain an alloy of at least one element selected from and aluminum.

(6) In the metal refining method according to the second aspect, the environmental atmosphere in which the metal-containing material is arranged is set to have less moisture than the atmospheric environment around the environmental atmosphere, and the metal-containing material is heated and melted. The metal is taken out from the metal-containing material.

(7) In the metal refining method according to the above aspect, the molten metal treatment may be performed after the heating and melting, and the molten metal treatment may be performed under conditions where the water content is less than that in the atmospheric environment.

(8) The metal refining apparatus according to the third aspect has a housing capable of forming a closed reaction space and storing the metal-containing material, a heating unit for heating the stored metal-containing material, and the above. It is provided with a supply unit connected to the housing and supplying gas into the housing, and a dehumidifying unit connected to the supply unit to dehumidify the moisture in the housing.

(9) The metal smelting device according to the above aspect may be connected to the housing and further include a discharge unit for discharging gas from the housing, and the discharge unit may be connected to the dehumidification unit.

(10) The metal refining apparatus according to the above aspect includes a furnace body for storing the metal-containing material, a water-impervious layer covering the opening surface of the furnace body, and a heating unit for heating the stored metal-containing material. You may prepare.

According to the dross generation suppressing method and the metal refining method according to the above aspect, the dross generation can be easily suppressed.

It is sectional drawing of the melt after heating and melting an aluminum alloy in an atmospheric environment. It is the figure which showed typically the reason why dross occurred. It is a flow chart of a metal refining method. It is a schematic diagram of the 1st example of the metal refining apparatus which concerns on this embodiment. It is a schematic diagram of the 2nd example of the metal refining apparatus which concerns on this embodiment. It is a schematic diagram of the 3rd example of the metal refining apparatus which concerns on this embodiment. It is a schematic diagram of the 4th example of the metal refining apparatus which concerns on this embodiment. It is a schematic diagram of the 5th example of the metal refining apparatus which concerns on this embodiment. It is a schematic diagram of the apparatus used in an Example and a comparative example. It is a photograph which photographed the surface of the AlMg ingot after the treatment of Example 1. It is a photograph of the surface of the AlMg ingot after the treatment of Comparative Example 1. It is a figure which shows the result of Example 2. FIG.

Hereinafter, the present embodiment will be described in detail with reference to the figures as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of the respective components may differ from the actual ones. is there. The materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

"Method of suppressing the occurrence of dross"
First, dross will be described. FIG. 1 is a cross-sectional view of a melt after heating and melting an aluminum alloy in an atmospheric environment. The melt has a metal layer M and a dross layer D. The metal layer M is a layer in which the metal contained in the molten metal-containing material is solidified. The dross layer D is a layer containing a by-product (dross) produced by heating and melting. Dross is mainly composed of molten metal oxides, unrecovered metals and nitrides, and in actual operation, flux-derived chlorides and fluorides that are added for the purpose of separating the dross layer and the metal layer. Etc. are included. Dross occurs when various metals are melted and melted. Dross is sometimes referred to as slag, slag, or ash.

Dross generated during melting and molten metal treatment causes various problems. For example, as the amount of dross generated increases, the amount of metal that can be extracted from the melt decreases. Further, the dross layer D inhibits heat transfer from the surface side of the melt, which causes an increase in the amount of energy required for melting and molten metal treatment. Further, the dross adheres to the refractory bricks of the melting furnace or the like and causes deterioration of the refractory bricks. Further, if dross intervenes in the metal layer M, it causes deterioration of product quality. Further, when the amount of metal that can be taken out from the melt is reduced due to dross, the concentration of impurities contained in the metal is increased, which causes deterioration of product quality.

In the method for suppressing the generation of dross according to the present embodiment, the environmental atmosphere in which the metal-containing material is arranged is set to have less moisture than the atmospheric environment around the environmental atmosphere, and the metal-containing material is heated and melted.

The metal-containing material contains a metal that causes dross. The metal-containing material is, for example, a simple substance metal of aluminum, or at least one element selected from the group consisting of magnesium, zinc, lithium, potassium, sodium, calcium, iron, titanium, cerium, thorium, and beryllium, and aluminum. It is an alloy with. The metal content is, for example, an aluminum alloy. If the metal content contains one selected from the group consisting of aluminum, magnesium, zinc, lithium, potassium, sodium, calcium, iron, titanium, cerium, thorium and beryllium, it will oxidize in reaction with water and cause dross. It becomes easy to form. Further, an element such as magnesium that easily occludes hydrogen promotes the reaction shown in FIG. 2 described later, and promotes the generation of dross.

Aluminum alloy is an example of metal-containing material. Aluminum alloys are prone to dross, and the treatment of dross is a problem.

Aluminum alloys are pure aluminum alloys (1000 series in JIS standard), Al—Cu alloys (2000 series in JIS standard), Al-Mn alloys (3000 series in JIS standard), Al—Si alloys. (4000 series in JIS standard), Al-Mg alloy (5000 series in JIS standard), Al-Mg-Si alloy (6000 series in JIS standard), Al-Zn-Mg alloy (5000 series in JIS standard) Dross occurs in any case of 7000 series), Al—Li alloy (8000 series in JIS standard) and the like.

When the alloying element is magnesium or lithium, hydrogen is easily taken into the crystal structure, and dross is particularly likely to occur due to the reaction with water. For example, Al—Mg-based alloys are more prone to dross than pure aluminum-based alloys. Alloy elements are contained, for example, in alloys on the order of a few percent. The abundance ratio of the alloying elements is, for example, 10% or less in terms of weight percent concentration. If the abundance ratio of alloying elements such as magnesium is high, dross is likely to occur.

The temperature at which the metal-containing material is heated and melted is determined by the metal species constituting the metal-containing material. When the temperature at which the metal-containing material is heated and melted is lower than the range in which the metal-containing material can be heated and melted, the occurrence of dross can be suppressed. For example, when the metal-containing material is an aluminum alloy, the temperature is preferably 700 ° C. or higher and 1300 ° C. or lower, and more preferably 740 ° C. or higher and 800 ° C. or lower. Further, for example, when the metal-containing material is a magnesium alloy, the temperature is preferably 600 ° C. or higher and 1200 ° C. or lower. For example, when the metal content is a zinc alloy, the temperature is preferably 300 ° C. or higher and 800 ° C. or lower. The higher the temperature, the more likely it is that dross will occur.

The environmental atmosphere at the time of heating and melting shall be a condition where the water content is less than the atmospheric environment. For example, the water content in the environmental atmosphere is preferably 2000 ppm or less, more preferably 1500 ppm, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less in terms of volume fraction. The water content can be converted from the dew point temperature measured by the dew point meter. A water content of 2000 ppm is a dew point temperature of about -13 ° C., and a water content of 1200 ppm is a dew point temperature of about -18 ° C. It is preferable that the higher the heating temperature, the smaller the amount of water in the environmental atmosphere. For example, when the heating temperature is 740 ° C. or higher and 800 ° C. or lower, the water content in the environmental atmosphere is preferably 5000 ppm or less, more preferably 4000 ppm or less, and further preferably 2000 ppm or less.

Beryllium may be added to the metal-containing material. Beryllium forms a dense surface oxide film on the surface of the molten metal. The surface oxide film is a barrier that inhibits contact between the metal-containing material and oxygen or hydrogen, and suppresses the reaction between the metal-containing material and oxygen or hydrogen.

According to the method for suppressing the generation of dross according to the present embodiment, the generation of dross can be suppressed beyond expectations even in an oxygen coexisting environment.

For example, when the metal content is an aluminum alloy, the oxidation of aluminum occurs by the following two reaction formulas.
4Al + 3O ₂ → 2Al ₂ O ₃ ... (1)
2Al + 3H ₂ O → 3H ₂ + Al ₂ O ₃ ... (2)
That is, aluminum reacts with oxygen or moisture to produce dross.

The method for suppressing the generation of dross according to the present embodiment can effectively suppress the generation of dross by suppressing the reaction formula (2) even in an environment where the reaction formula (1) can occur. It can be expected that oxygen and water will affect the formation of dross (oxide), but it is true that reducing the amount of water significantly reduces the amount of dross generated despite the presence of oxygen. It exceeds the expectations of the vendor. The reason for this is not clear, but it is thought that the following points are related.

FIG. 2 is a diagram schematically showing the reason for the occurrence of dross. FIG. 2 is an image of a cross section of the molten melt, and the melt has a melt region Me and a surface region S. Oxygen and water that cause the generation of dross invade the melt from the surface region S side. The invading oxygen and water react with aluminum to produce oxides.

The reaction between aluminum and oxygen is represented by the reaction formula (1), and only aluminum oxide is produced. The reaction equation (1) does not produce a by-product, and the reaction is considered to be completed in the surface region S. On the other hand, the reaction between aluminum and water is represented by the reaction formula (2), and aluminum oxide and hydrogen as a by-product are generated. Hydrogen spreads in the melt. In the case of the reaction formula (2), hydrogen generated as a by-product affects the molten region Me. This relationship is not limited to the case where the metal species is aluminum, and the same applies to the case of other metal elements.

It is considered that the generation of dross due to oxygen is contained in the surface region S, while the generation of dross due to water affects the molten region Me. That is, it is considered that if the water content in the environment is suppressed, the reaction in which dross is generated can be stopped in the surface region S, and the generation of dross can be effectively suppressed even in an oxygen coexisting environment.

For example, magnesium easily reacts with hydrogen, as mentioned in hydrogen storage alloys. It is consistent with the above consideration that dross is likely to occur when the aluminum alloy contains magnesium. This is because it is considered that magnesium attracts the hydrogen generated in the reaction formula (2) to the deeper part of the molten region Me, and the reaction is promoted.

Further, according to the method according to the present embodiment, the generation of bubbles in the melt can be suppressed. According to the method according to the present embodiment, the water content in the environment is suppressed, and the above reaction formula (2) is suppressed. That is, hydrogen is less likely to be generated inside the melt, and hydrogen is less likely to be incorporated into the melt. Hydrogen incorporated into the melt causes the generation of bubbles during solidification. Bubbles become defects in refined metal.

"Metal refining method"
As the metal refining method according to the present embodiment, the above-mentioned dross generation suppressing method is used. FIG. 3 is a flow chart of a metal refining method. The metal refining method includes a melting process of heating and melting a raw material, a molten metal treatment of adjusting a molten metal (melted metal) melted by heating, and a casting process of casting the molten metal. The metal refining method according to the present embodiment is a method for producing a metal from scrap or the like.

The melting process is a process of heating and melting the raw material. The melting process is a process in which dross is generated. The above method for suppressing the generation of dross is applied to the melting treatment according to the present embodiment. In the melting process, the raw material is heated and melted under conditions where the water content is less than that in the atmospheric environment.

The raw material is, for example, a metal-containing substance such as cutting chips, scrap, and ingot. The metal-containing material is the same as that presented in the method for suppressing the generation of dross. The heating and melting temperature and the environmental atmosphere at the time of heating and melting are the same as those presented in the method for suppressing the generation of dross.

The molten metal treatment is a process of adjusting the molten metal by adding flux and alloying elements to the molten liquid (molten metal). The molten metal treatment is a process in which dross is generated. The above-mentioned method for suppressing the generation of dross is applied to the molten metal treatment according to the present embodiment. The molten metal treatment is performed under conditions where the water content is less than that of the atmospheric environment. The environmental atmosphere during the molten metal treatment is the same as that presented in the method for suppressing the generation of dross.

The casting process is the process of cooling the molten metal and hardening it again. By solidifying the molten metal, a solid metal is produced.

As described above, according to the metal refining method according to the present embodiment, dross generated in each step can be suppressed. Therefore, the energy loss and the increase in cost due to the generation of dross can be suppressed. In addition, the concentration of impurities and the increase of inclusions due to the formation of dross are suppressed, and the quality of the product can be improved. Further, the reaction between the nitride generated by the reaction between the molten metal and nitrogen in the atmosphere and water can be suppressed, and the generation of ammonia which causes a foul odor can be suppressed. Further, the uptake of hydrogen into the melt is suppressed, and the generation of bubble defects can be suppressed.

"Metal refining equipment"
The metal refining apparatus according to the present embodiment is an apparatus used for the above-mentioned melting treatment and molten metal treatment, and can heat and melt metal-containing substances under conditions where the water content is less than that in the atmospheric environment.

FIG. 4 is a schematic view of a first example of the metal refining apparatus according to the present embodiment. The metal refining apparatus ME1 according to the first example includes a housing C, a heating unit H, a supply unit p1, a dehumidifying unit Dh, a discharge unit p2, a pump P, and a dew point meter Dp.

The housing C forms a reaction space R closed inside. The metal-containing material m can be stored in the housing C. The metal-containing material m is housed in the crucible CR, for example, and melts in the crucible CR. The heating unit H heats the metal-containing material m. The heating unit H is, for example, a heater, a burner, or the like. The heating unit H heats the metal-containing material m from the outside of the housing C, for example. The heating unit H may be installed in the housing C as long as it does not release moisture from itself by heating.

The supply unit p1 and the discharge unit p2 are connected to the housing C. The supply unit p1 supplies gas into the housing C. The discharge unit p2 is connected to the pump P and discharges gas from the housing C. The supply unit p1 is, for example, an air supply pipe that supplies gas into the housing C. The discharge unit p2 is, for example, an intake pipe that sucks out gas from the housing C. In the metal refining apparatus ME1 according to the first example, the supply unit p1 and the discharge unit p2 are connected to the dehumidification unit Dh. In the metal refining apparatus ME1 according to the first example, gas circulates through the dehumidifying portion Dh. The dehumidifying section Dh reduces the amount of water in the reaction space R. The dehumidifying section Dh has a desiccant such as silica gel.

FIG. 5 is a schematic view of a second example of the metal refining apparatus according to the present embodiment. The metal refining apparatus ME2 according to the second example includes a housing C, a heating unit H, a supply unit p1, a dehumidifying unit Dh, a discharge unit p2, a pump P, and a dew point meter Dp. The metal refining apparatus ME2 according to the second example is different from the first example in that the discharge portion p2 is not connected to the dehumidifying portion Dh. In the second example, the same configuration as in the first example will not be described. The air in the reaction space R does not circulate but flows in one direction. The heat generated in the heating portion H is transferred to the metal-containing material m in the crucible CR via the wall surface of the housing C, and the metal-containing material m is melted. The heating unit H may be a natural gas burner or the like containing a large amount of water in the exhaust gas.

FIG. 6 is a schematic view of a third example of the metal refining apparatus according to the present embodiment. The metal refining apparatus ME3 according to the third example includes a housing C, a heating unit H, a supply unit p1, a dehumidifying unit Dh, a discharge unit p2, a pump P, and a dew point meter Dp. The metal refining apparatus ME3 according to the third example is different from the second example in that the heating unit H is an indirect heating method in which the supply unit p1 is provided. In the third example, the same configuration as in the second example will not be described. The dry gas dehumidified by the dehumidifying unit Dh flows in the supply unit p1. The dry gas is heated by the heating unit H and sent to the metal-containing material m. The heated dry gas heats the metal-containing material m and melts it.

FIG. 7 is a schematic view of a fourth example of the metal refining apparatus according to the present embodiment. The metal refining apparatus ME4 according to the fourth example has a furnace body CR, an impermeable layer WB, and a heating unit H. The furnace body is composed of at least a metal-containing material and a boundary member for isolating the metal-containing material from the surrounding environment. The metal-containing material m is housed in the furnace body CR. The impermeable layer WB covers the opening surface of the furnace body CR. The impermeable layer WB is a film that suppresses the permeation of water. The impermeable layer WB is, for example, a carbon plate. Moisture in the gas phase is removed by the reaction of C + H ₂ O = CO + H ₂ . The heating unit H heats the metal-containing material m and melts the metal-containing material m. The heating unit H is, for example, a burner. Moisture contained in the exhaust gas of the burner reacts in the impermeable layer WB, and it is difficult to reach the metal content m. The impermeable layer may be formed as long as a layer for keeping the surface of the metal-containing material in a dry state is formed, and may be formed by supplying, for example, a heated dry gas. By using a heated dry gas, it can also serve as a heating unit.

FIG. 8 is a schematic view of a fifth example of the metal refining apparatus according to the present embodiment. The metal refining apparatus ME5 according to the fifth example has a heating unit H and a gas pipe Gp. The heating unit H is, for example, a burner. The gas pipe Gp covers the periphery of the heating portion H and supplies a dry shield gas between the heating portion H and the gas pipe Gp. The shield gas is, for example, argon, carbon dioxide, or air. The metal-containing substances m1 and m2 are heated by the heating unit H to form a melt mel. By supplying the shield gas from the gas pipe Gp, it is possible to suppress the supply of water to the melt mel.

As described above, the present invention is not limited to the above-described embodiments and modifications, and various modifications and modifications can be made within the scope of the gist of the present invention described within the scope of claims.

FIG. 9 is a schematic view of the device used in the examples and comparative examples. The device 100 includes a reaction tube 10, an electric furnace 20, a data logger 30, a humidifying device 40, a gas supply unit 50, and a dew point meter 70.

The reaction tube 10 has a mounting table 11, a thermocouple 12, a support table 13, a weighing scale 14, and a window 15. The reaction tube 10 is a vertical quartz reaction tube. The mounting table 11 mounts the crucible 60. The mounting table 11 is supported by the support table 13, and the thermocouple 12 is installed on the back surface. The thermocouple 12 measures the temperature of the crucible 60. The weight scale 14 detects a change in the weight of the crucible 60. The state of the melt in the crucible 60 can be confirmed from the window 15.

The electric furnace 20 is arranged around the crucible 60 and heats the crucible 60. As the electric furnace 20, a high-frequency induction heating furnace was used. The data logger 30 records the temperature change and the weight change of the crucible 60. The humidifying device 40 is connected to the reaction tube 10 and determines the water content of the gas supplied to the reaction tube 10. The amount of water in the gas is measured with a dew point meter 70. The Tekne TK-100 was used as the dew point meter.

The gas supply unit 50 is connected to the reaction tube 10 and supplies gas to the reaction tube 10. The gas supply unit 50 includes a cylinder 51, a dehydration column 52, a deoxidizing column 53, and a mass flow controller 54. For the cylinder 51, G1 grade argon, nitrogen and oxygen cylinders were prepared respectively. As the dehydration column 52, a dehydration column DC-A4 manufactured by Nikka Seiko Co., Ltd. was used. The deoxidizing column 53 is connected only to the argon and nitrogen cylinders 51. As the deoxidizing column 53, a deoxidizing column GC-RX manufactured by Nikka Seiko Co., Ltd. was used. The mass flow controller 54 adjusts the amount of argon, the amount of nitrogen, and the amount of oxygen supplied to the reaction tube 10, respectively.

(Example 1)
About 50 g of AlMg ingot cut into 2 cm squares was weighed. The AlMg ingot contains 10% of Mg in weight percent concentration. This raw material was put into the same crucible as the crucible 60, pre-melted in a high-frequency induction heating furnace in an argon gas atmosphere to form a lump, and the dross slightly formed on the surface was cut with a cutter. The obtained massive sample was put into a crucible 60 and melted by heating. For the crucible 60, a dense alumina crucible was used.

As for the gas, the supply amount of nitrogen was 780 cc / min, the supply amount of oxygen was 210 cc / min, and the supply amount of argon was 10 cc / min, and a total of 1000 cc / min of gas was supplied. After the gas merged, the dew point of the gas was measured at 10 second intervals. The reproducibility test was performed four times, and the dew point was in the range of -15.2 ° C to -23.3 ° C. This corresponds to 761 ppm to 1631 ppm in terms of water content.

Under the above conditions, the Al-10% Mg ingot was heated at 800 ° C. for 90 minutes and then cooled. FIG. 10 is a photograph of the surface of the AlMg ingot after the treatment of Example 1. The weight change rate of the ingot in Example 1 was 1% or less.

(Comparative Example 1)
The difference from Example 1 is that the merged gas is blown into about 500 mL of ultrapure water at room temperature, humidified and supplied. The water content after humidification was about 20 ° C. (2.3%) at the dew point, which was equivalent to the water content in the atmospheric environment. FIG. 11 is a photograph of the surface of the AlMg ingot after the treatment of Comparative Example 1. The weight change rate of the ingot in Comparative Example 1 was 12.6% or less.

Comparing Example 1 and Comparative Example 1, the weight change of the ingot was small in Example 1, and no dross was confirmed in appearance. In Example 1, although the Mg is contained in an amount of 10% by weight, the occurrence of dross is remarkably suppressed.

(Example 2)
In Example 2, the tendency of dross to occur was determined by changing the amount of water in the reaction space and the heating temperature.
FIG. 12 shows when about 40 g of an Al-4.5 mass% Mg alloy molten metal is heated at a predetermined temperature for 90 minutes under an air atmosphere (N ₂ : 79 vol%, O ₂ : 21 vol%) having different water contents. (Numerical value in parentheses in FIG. 12: mass%) was determined. The conditions of the amount of water in the reaction space and the heating temperature were changed by experiments. In FIG. 12, virtual lines having weight increase rates of 0.1%, 1.0%, and 5.0% are shown by dotted lines.

The relationship between the amount of water in the experimental reaction space and the heating temperature is shown below. The alloy molten metal installed in the crucible is previously heated and melted in a dry argon atmosphere, and its specific surface area is about 2.0 cm ² / g.
Heating temperature: 800 ° C., Moisture content: 10734ppm, Weight increase rate: 6.2% by mass
Heating temperature: 800 ° C, water content: 6232ppm, weight increase rate: 3.0% by mass
Heating temperature: 800 ° C, water content: 3396ppm, weight increase rate: 0.53% by mass
Heating temperature: 750 ° C, water content: 8492 ppm, weight increase rate: 5.7 mass%
Heating temperature: 750 ° C, water content: 4941 ppm, weight increase rate: 3.3 mass%
Heating temperature: 730 ° C, water content: 8732 ppm, weight increase rate: 1.1 mass%
Heating temperature: 730 ° C, water content: 4504 ppm, weight increase rate: 0.16 mass%

As shown in FIG. 12, the higher the water concentration, the higher the weight increase rate, and the occurrence of dross tended to increase. The tendency was more remarkable as the heating temperature was higher.

10 reaction tube, 11 mounting table, 12 thermocouple, 13 support table, 14 mass flow controller, 15 window, 20 electric furnace, 30 data logger, 40 humidifier, 50 gas supply unit, 51 cylinder, 52 dehydration column, 53 removal Oxygen column, 54 mass flow controller, 60, CR crucible, 70, Dp dew point meter, 100 device, C housing, Dh dehumidifier, H heating section, ME1, ME2, ME3 metal refining device, P pump, p1 supply section, p2 Discharge part, R reaction space, WB impermeable layer, Gp gas pipe

Claims (10)

1. A method for suppressing the generation of dross, in which the environmental atmosphere in which the metal-containing material is arranged is set to have less moisture than the atmospheric environment surrounding the environmental atmosphere, and the metal-containing material is heated and melted.
2. The method for suppressing the generation of dross according to claim 1, wherein the metal-containing material is heated and melted while controlling the amount of water in the environmental atmosphere.
3. The method for suppressing the generation of dross according to claim 2, wherein the control of the water content is performed so that the water content does not increase.
4. The method for suppressing the generation of dross according to any one of claims 1 to 3, wherein the water content in the environmental atmosphere at the time of heating and melting is 2000 ppm or less.
5. The metal-containing substance is a simple substance of aluminum, or at least one element selected from the group consisting of magnesium, zinc, lithium, potassium, sodium, calcium, iron, titanium, cerium, thorium, and beryllium, and aluminum. The method for suppressing the generation of dross according to any one of claims 1 to 4, which comprises an alloy.
6. A metal refining method in which the environmental atmosphere in which the metal-containing material is arranged is set to have less moisture than the atmospheric environment surrounding the environmental atmosphere, the metal-containing material is heated and melted, and the metal is taken out from the metal-containing material.
7. After the heat melting, the molten metal treatment is performed.
   The metal refining method according to claim 6, wherein the molten metal treatment is performed under conditions where the water content is less than that of the atmospheric environment.
8. A housing that forms a closed reaction space inside and can store metal-containing materials,
   A heating unit that heats the stored metal-containing material,
   A supply unit connected to the housing and supplying gas into the housing,
   A metal smelting device including a dehumidifying unit connected to the supply unit and reducing water content in the housing.
9. Further provided with a discharge unit connected to the housing and discharging gas from the housing,
   The metal smelting apparatus according to claim 8, wherein the discharge unit is connected to the dehumidification unit.
10. The furnace body that houses the metal-containing material and
    An impermeable layer that covers the opening surface of the furnace body and
    A metal refining apparatus including a heating unit for heating the contained metal-containing material.

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