WO2025127545A1 - Method for controlling impurities in molten aluminum scrap - Google Patents

Abstract

The present invention relates to a method for controlling impurities in molten aluminum scrap, comprising the steps of: melting a metal material containing aluminum, thereby forming a molten metal and an impurity remover containing boron; reacting, in the molten metal, the boron with at least some of the impurities contained in the metal material, thereby forming a reaction product; and separating the reaction product from the molten metal, wherein the impurities contain a transition metal, the transition metal includes at least one from among titanium, chromium, vanadium and zirconium, the reaction product is in the form of MB₂, where M is the transition metal, and the impurity remover is an alloy of boron and aluminum.

Description

Method for controlling impurities in molten aluminum scrap

The present invention relates to a method for appropriately controlling impurity elements other than aluminum contained in aluminum scrap in order to recycle the aluminum scrap and use it by dividing it by grade according to its appropriate use.

Aluminum is manufactured and used in various ways. Currently, the most common way to produce aluminum is to obtain aluminum ingots (primary ingots) through ore treatment/smelting/refining from bauxite. The next way is to collect aluminum scraps and re-melt them. The former method generates _CO2 , various chlorine ( _Cl2 ) gases, and red mud during the aluminum manufacturing process. In particular, the amount of _CO2 generated at this time is 16.5 t CO2eq per ton of aluminum ingot produced, whereas when aluminum scraps are used, the _CO2 generated from the raw materials used is zero, and about 0.5 to 0.7 t _CO2eq is derived from the energy fuel used to operate the melting furnace, so it can be said that there is a significant _CO2 reduction effect.

In this situation, when recycling aluminum scrap, the work of selectively sorting the scrap is somewhat difficult, and a lot of physical and human energy is consumed in the separation process. Currently, scrap is sorted according to the ISRI (Institute of Scrap Recycling Industries, Inc.), but in many cases, a large amount of unsorted scrap is mixed and generated, so a technology that uses it all at once is necessary.

With this technology, the remaining elements except aluminum among various scraps are considered as impurities, and if the impurities are contained and controlled, the purity of aluminum can be further increased, so technology development for this is necessary.

The purpose of the present invention is to provide a method for controlling impurities in a molten aluminum scrap.

The above object of the present invention is achieved by a method for controlling impurities in a molten aluminum scrap, comprising: a step of melting a metal material including aluminum to form a molten aluminum and an impurity remover including boron; a step of reacting at least a portion of the impurities included in the metal material with the boron in the molten aluminum to form a reactant; and a step of separating the reactant from the molten aluminum, wherein the impurity includes a transition metal, the transition metal includes at least one of titanium, chromium, vanadium, and zirconium, and the reactant is in the form of MB ₂ , wherein M is the transition metal, and the impurity remover is an alloy of boron and the aluminum.

The above boron alloy comprises 1 to 20 wt% boron, an additional component and the remainder aluminum, wherein the additional component comprises at least one of chromium, titanium, vanadium and zirconium, and the weight of the additional component can be 0.2 to 1.5 wt% of the boron.

The step of separating the reactants from the molten metal may include a step of first stirring the molten metal; a first dross removal step of removing dross after the first stirring; a step of precipitating the reactants in the molten metal after the first dross removal; a step of second stirring the molten metal after the precipitation; and a second dross removal step of removing dross after the second stirring.

The above precipitation can be performed for 30 minutes to 8 hours.

The temperature of the molten metal during the above precipitation may be 850 to 950°C.

The formation of the molten metal and the formation and removal of the impurities are performed in a melting furnace, and after the removal of the impurities, the step of discharging the molten metal from the melting furnace into a bath; and the step of injecting an impurity remover into the molten metal in the bath may be further included.

The above impurity remover can be added to the molten metal flowing in a straight direction without stirring from the outside of the melting furnace.

The amount of impurity remover added to the molten metal in the above bath may be 0.5 g to 2.0 g per kg of the molten metal.

The amount of impurity remover added to the molten metal in the above-mentioned bath may be 8% to 30% of the amount of impurity remover supplied to the molten metal in the melting furnace per molten metal weight.

The above-mentioned bath includes a spout, an upstream bath, a pond, a middle bath, a heating furnace, and a downstream bath, which are arranged sequentially along the direction of progression of the molten metal, and the impurity remover can be supplied to the upstream bath.

The above pond may have a vertical cross-sectional area in the direction of progression of the molten metal that is 3 to 30 times greater than that of the above upstream tank.

In the case of scrap, it is difficult to accurately sort the 1,000 to 9,000 series. Among them, UBC (Used Beverage Can, hereinafter referred to as ‘UBC’), which accounts for the largest amount of scrap, is sorted to some extent, but considering the operability, etc., it is easier to manufacture aluminum deoxidizers and alloys for steelmaking by using mixed scraps together.

The present invention provides a method for controlling impurities in the process of manufacturing an aluminum deoxidizer and alloy using collected aluminum scrap.

Figure 1 is a flow chart of an impurity control method according to one embodiment of the present invention.

Figures 2 and 3 show the melting furnace type used in the experimental example.

Figure 4 is a schematic diagram of a cross-section of a sample obtained in an experimental example.

Figure 5 is a schematic diagram of a cross-section of the molten metal in an experimental example.

Figure 6 shows the tank used in Experimental Example 7.

Figure 7 is a plan view of the heating furnace in Experimental Example 7.

The present invention relates to a deoxidizer for high-purity steelmaking and impurity control for alloy production using aluminum of the 1,000 to 9,000 series, but is not limited thereto.

Aluminum scrap uses various types of scrap as shown in Table 1. The Ti content in each scrap can vary from 0.001 to 0.15 wt%. The Cr content in each scrap can vary from 0.002 to 0.40 wt%. Although not limited thereto, the Cr content can be higher than the Ti content. Other elements can be included to the extent of examples in Table 1. At this time, the content of impurities cannot be limited, and the type appears differently depending on the type of scrap.

<Table 1> Weight %

The present invention uses an impurity remover (S0, additive) containing boron, and specifically, may include a method of adding boron, an aluminum boron alloy, an aluminum boron titanium alloy, or boron in a molten state. The impurity to be removed may be a transition metal, particularly titanium, and may further include at least one of chromium, vanadium, zirconium, and manganese.

The following description mainly exemplifies a process for manufacturing an aluminum deoxidizer from which impurities are removed (reduced) from aluminum scrap, but the present invention is not limited thereto. In addition, the removal of impurities is mainly exemplified by the removal of titanium, but the present invention is not limited thereto.

In the following description, % means weight % unless otherwise stated.

Hereinafter, a method for controlling impurities in a method for manufacturing an aluminum deoxidizer according to one embodiment of the present invention will be described with reference to FIG. 1.

First, when aluminum bases of 1,000 to 9,000 series aluminum are received as aluminum scrap, they are classified by type and stored. In particular, foreign substances such as iron cans and iron columns are sorted and classified, and foreign substances such as wood and film are sorted (S1).

Scrap is mixed appropriately based on aluminum for each raw material, targeting the deoxidizer (S2).

Next, it goes through the melting process (S3). At this time, to prevent the loss of heat energy by supplying cold scrap directly to the molten metal, the moisture and oil are dried in a drying zone (150~400℃) inside the melting furnace for several minutes to several tens of minutes, and then melting is carried out in the molten metal.

The melting temperature may be 700°C to 1300°C when radiant heat is used, and 550°C to 870°C or 650°C to 900°C when direct heat is used. The melting time may take 1 hour to 8 hours depending on the mass to be dissolved.

Next, S0 (impurity remover or additive) is added. As shown in Fig. 2 or Fig. 3, pre-melted S0 (B, Al-Bx, Al-Ti-B, etc.) can be added under the same temperature conditions or can be added in a solid state. In continuous operation, a method of putting the additive in an additive tank and injecting it into a melting furnace can be used.

Figure 2 shows a case where a reflector furnace is used as a melting furnace, and Figure 3 shows a case where a rotary furnace, induction furnace, or electric furnace is used as a melting furnace.

In Fig. 2, each reference number represents 1 for the melting furnace, 100 for the additive, 101 for the additive tank, 200 for the aluminum melt, 201 for the EMS, 202 for the melting furnace, 203a and 203b for the burners, and 204 for the atmosphere.

In Fig. 3, each instruction number indicates that 2 represents a melting furnace, 100 represents an additive, 101 represents an additive tank, 103 represents an additive inlet, 200 represents molten aluminum, 204 represents the atmosphere, 300 and 301 represent impellers, and 304 represents a spout.

S0 may be an aluminum-boron alloy. The boron alloy may contain 0.1 to 20 wt % or 0.1 to 5 wt % boron and the remainder aluminum.

Boron in S0 forms an intermetallic compound with aluminum, specifically, it can be AlB ₂ or AlB ₁₂ , and it can be in the form of AlxByM1z with a third element (additional component) M1 in addition to aluminum and boron.

As shown in Table 2, M1 contains V, Ti, Cr, Zr, etc., and it is also possible to use a material in which Ti is not present at all. The weight of M1 can be 0.2 to 1.5% or 0.2 to 0.4% of the weight of B.

<Table 2>

The amount of S0 used can be adjusted to be 0.1 to 5.0 times or 0.8 to 2.0 times the molar ratio of the transition metal in the scrap to be removed.

Alternatively, the amount of S0 used can be adjusted to 0.0005 to 1.2 times or 0.002 to 0.08 times the weight ratio of the metal material (aluminum scrap).

When first stirred (S4) in a molten state, the transition metal (M) and boron react to form a reactant.

An example of the formation of a reactant (MB ₂ ) is as shown in Equation 1 below.

Equation 1> AlB ₂ (s,l) + M(l) → Al(l) + MB ₂ (S)

Equation 2> AlB ₁₂ (s,l) + M(l) → Al(l) + MB ₂ (S)

At this time, the molten metal is stirred or ultrasonically treated to increase the effective collision number of AlB ₂ or AlB ₁₂ that did not react.

Primary stirring can be performed at 100 rpm to 400 rpm for 30 minutes to 8 hours or 3 hours to 5 hours.

For EMS (Electro magnetic stirrer), it can be 10 to 350 Hz, 100 to 300 Hz, 200 to 250 Hz or 150 to 250 Hz.

In addition, although the solid injection method and the liquid injection method of injecting S0 into the molten metal ultimately show similar results for Ti control, the molten metal injection method can provide convenience in terms of shortening the reaction time, safety during the operation process, environment, etc., and workability.

The next process is the first dross removal process, which is a process to remove dross generated after stirring and reaction of S0 (S5).

At this time, inert gas can be injected into the molten metal to remove impurities more effectively. The use of inert gas can improve castability by surfacing and removing H ⁺ and oxides when manufacturing alloys.

S6 is a step for precipitating the reactants after stirring. This is done to increase the particle size of TiB ₂ through precipitation and to facilitate removal of the precipitated ones from the bottom. In addition, by providing precipitation time, the reaction time of Ti and B can be increased.

The precipitation time can be from 30 minutes to 8 hours or from 1 hour to 2 hours. The precipitation temperature can be from 680 to 950°C or from 720 to 800°C. Stirring may not be performed during the precipitation.

After the sedimentation time, the second stirring (S7) is performed again, and the Ti that did not react at the top reacts with B once again, and in the process, TiB ₂ floats up as dross (S8, secondary dross removal). Dross removal is performed because it is easier to float than to remove the sediment for production. After the process, S9 is drawn out and cast.

Secondary stirring can be performed at 100 rpm to 400 rpm for 30 minutes to 8 hours or 3 hours to 5 hours.

For EMS (Electro magnetic stirrer), it can be 10 to 350 Hz, 100 to 300 Hz, 200 to 250 Hz or 150 to 250 Hz.

Finally, the most important part in the continuous production method is that the aluminum product has a constant chemical composition. In the present invention, by adding S0 once more (S10) to the melting pot during the melting process, a product is manufactured in which the impurity content is stably maintained at a low level.

The amount of S0 supplied to the molten metal from the hot-water bath is 0.5 g to 2.0 g or 0.7 g to 1.3 g per kg of molten metal being poured. Alternatively, the amount of S0 supplied to the molten metal from the hot-water bath is 8% to 30% or 10% to 20% of the amount of S0 supplied to the molten metal from the melting furnace per weight of the molten metal.

As shown in Fig. 6, the hot water tank may be composed of a melting furnace wall (c1), a spout (c2), an upstream hot water tank (c3), a pond (c4), a midstream hot water tank (c5), a heating furnace (c6), a downstream hot water tank (c7), a filter zone (c8), and a casting (c9). S0 may be injected from the double upstream hot water tank (c3), and the injection may be intermittent or continuous.

The tank, especially the upper tank, may be a trench-shaped tank with a cover provided on the upper part. S0 may be poured into the upper part of the molten metal by opening a part of the cover or by providing an inlet in the cover.

The molten metal into which S0 is injected in the upper stream flows in one direction without separate stirring. Here, the one direction can be a straight line.

The reason for pouring water from the upstream water tank is that the water flow rate at the outlet is fast and the water flow rate at the upstream water tank is relatively stable.

The pond is intended to provide overflow protection. It can have a length and width that are two to five times larger than the upstream tank. The reaction of Ti + B mainly occurs in the pond.

In other embodiments, agitation may be applied to the pond to increase the reaction rate.

The reaction product of Ti + B exists in a space below the heater, so it accumulates there and can be periodically removed.

There is a mesh (or ceramic filter) at the bottom of the filter zone to filter out impurities.

The present invention is explained in more detail through the following experimental examples.

Experimental Example 1 - S0 Input Form

Table 3 compares the change in titanium concentration according to stirring time when S0 is introduced as a solution and when it is introduced by dissolving it in a solid.

<Table 3>

In more detail, this compares the case where S0 is melted at 700℃ and then introduced, and the case where S0 is introduced as a solid at room temperature (25℃). The reaction conditions were 780℃, 200rpm stirring speed, 500kg of aluminum raw material, and 1kg of additive 4 as S0. The melting furnace type used was the same as that in Fig. 3. The composition of the aluminum raw material is as shown in Table 4. In the S2 process, scraps 1, scraps 2, and scraps 5 were applied to manufacture aluminum deoxidizer molten sample 1, and scraps 4, scraps 6, scraps 8, scraps 9, and scraps 10 were applied to manufacture aluminum deoxidizer molten sample 2, and an experiment was conducted.

<Table 4> Weight %

The experimental results show that the reaction occurs faster in the liquid Ti concentration. However, it shows an effect on the reactivity at the beginning of the injection, and after a certain period of time, similar results are shown, but the initial reaction speed is confirmed to be improved.

Experimental Example 2 - S0 Type

S0 can be of the form AlxByM1z with a third element M1 other than aluminum and boron, examples of which are as follows.

The scrap was passed through S1 and S2 and then put into the melting furnace. At this time, the melting furnace used type 3, and the scrap used was scrap 2 collected from UBC beverage cans generated domestically. The basic reaction conditions were temperature 800℃, stirring speed 300rpm, 1.5kg of molten aluminum, 1 hour of melting, 7.5g of S0 addition, followed by S4 for 2 hours and S6 for 4 hours. At this time, the initial Ti content in the molten metal was 244ppm. The main conditions at this time were that S0 was not added, additive 4 of Table 2 in the AlxByM1z form and additive 5 in the AlxBy form were added respectively, and after going through steps S4, S5, and S6, it was quenched in a water tank. In order to confirm the precipitation of TiB ₂ and CrB ₂ by cutting the cross-section of the quenched sample, the sample was cut from the deep part of the cut surface to the outside as shown in the schematic diagram of Fig. 4 and analysis was performed. At this time, the cross-section was divided into six parts, and each side was cut into a grid pattern to conduct an analysis, divided into upper (①,②), middle (③,④), and lower (⑤,⑥). Component analysis was conducted using ICP and S-OES, and the Ti precipitate at the bottom was analyzed using OM/SEM/EDS.

The analysis results are as shown in Table 5. When using additives 4 and 5, the Ti removal rates were compared, and the two results showed similar results. The Ti removal rate of additive 4 in the AlxByMz form was 74.5%, and that of additive 5 in the AlxBy form was 73.6%, showing that additive 4 showed a slightly higher result. At this time, some of the B in S0 was able to react with Cr and be removed as CrB ₂ , and the Cr removal rate was confirmed to be approximately 42.4 to 43.2%.

<Table 5>

In the case of the lower part of ⑦ in Fig. 5, the Ti content was 2,900 ppm, and it was confirmed through the ICP results that a large amount of Ti was precipitated. It was confirmed that Ti, Cr, and V were concentrated in the lower part of 300 ㎛ or less.

Experimental Example 3 - Stirring Time and Dross Removal

Table 6 shows the experimental results for Ti control according to stirring time.

Scrap was manufactured by appropriately mixing scrap 1, scrap 2, scrap 5, scrap 8, and scrap 9 of Table 1, which are UBC, Talic, and Taboo types, and the Al content was 94.5 wt% and the Ti content was 446 ppm.

The melting temperature was 850℃, the melting furnace type of Fig. 3 was used, the aluminum molten metal capacity was 1 ton, S0 additive 3, 0.5 kg, and the S4 times were 0 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 160 minutes, 180 minutes, 210 minutes, and 240 minutes, and S9 was performed directly without going through steps S5, S6, S7, and S8. Table 6 shows the experimental results, which are the results of analyzing the Ti concentration using ICP/OES.

<Table 6>

Ti removal according to stirring time showed 89~90% Ti control effect at 240 minutes. Stirring can use EMS, EMP, and Agitator equipment. EMS (Electro magnetic stirrer) is an indirect stirring method that uses a magnetic field to make it rotate in the direction of the magnetic field. EMP (Electro magnetic pump) refers to a method that uses a liquid pump to add and remove molten metal and stirs using a pump. The agitator uses an impeller, and both EMS and EMP methods can be used in Melting Furnace 1, but only the agitator and EMP methods can be used in Melting Furnace 2.

Experimental Example 4 - Dross Removal

Since some aluminum is bound to come out together with the dross, this dross can be used in a separate process to recover aluminum metal.

To control impurities, an inert gas is injected during stirring to float the inclusions and oxygen in the molten metal, and after adding S0, the products such as TiBx, CrBx, CrMnx, and VBx can also be floated and removed with dross.

Experimental Example 5 - Injection of inert gas during stirring

Sample 3 of Table 4, which is a general aluminum deoxidizer manufactured by appropriately mixing Table 1, was used. The melting temperature was 750℃, and type 2 of the melting furnace of Fig. 2 was used. 200 kg of sample 3, 1.6 kg of S0 additive 3, stirring speed 300 rpm, S4 was performed for 120 minutes, and then S4 was performed for an additional hour while purging Ar gas (25 LPM). S7 was performed for 1 hour, and S9 was performed without performing S8.

Table 7 shows the results of analyzing Ti.

<Table 7>

As a result of calculating and analyzing all the quantities, the amount of Ti that can be removed by levitation was 37.2%, and the remaining 40% was removed by precipitation, so the total removal rate was 72.7%. From this, it can be confirmed that some Ti can be removed by levitation only by stirring. If the dross is removed after the first stirring, the Ti, Cr, etc. present in the molten metal can be reduced, and some of the remaining molten metal can be used for the next process.

The most important factors in precipitation reaction are temperature and time. When performing S6, the temperature can be 680~950℃ or 720~770℃. At high temperatures such as 850~950℃, rather than helping the precipitation reaction of aluminum, some _TiB2 type compounds may float upward, which may hinder precipitation.

Experimental Example 6 - Temperature and Time of Precipitation Reaction

The optimum conditions for temperature and time of the precipitation reaction were confirmed. 200 kg of sample 1 in Table 4, made through S1 and S2, was melted at 750℃ in a melting furnace type 2, 1.6 kg of S0 additive 4 was added, S4 was performed for 30 minutes, S5 was omitted, S6 was performed for 5 to 270 minutes, and the temperature at S5 was 780 to 900℃.

Table 8 shows the average results of analyzing the upper, middle, and lower parts of the sample after the reaction.

<Table 8>

As a result, the sedimentation time showed a sedimentation removal rate of over 90% at 90 minutes and 240 minutes. As shown in Fig. 8, when the lower part at 90 minutes and 240 minutes was observed by SEM, it was confirmed that the lower sedimentation layer was formed and sedimented. At 240 minutes, the size increased further and formed a T-shape. In addition, except for 90 minutes and 240 minutes, the results of analyzing the sample after the experiment showed that there were differences by section.

Table 8 shows the average analyzed by dividing the molten metal into levels as in Fig. 9, and Table 9 shows the results when the precipitation temperature is 900℃, from 30 to 240 minutes, with level 90 or higher being marked as the upper part, or “upper”, and level 30 or lower being marked as the lower part, or “lower” in the levels of Fig. 9. When the precipitation temperature is 850℃ or higher, if precipitation is performed for a period of time longer or shorter than the appropriate time, there is a phenomenon in which some Ti is picked up to the upper part. In this case, it is effective to perform S5 to remove dross and Ti together. Alternatively, only the middle level of 30 to 90% can be used.

<Table 9>

Looking at the results in Table 9, it can be confirmed that the Ti concentration in the upper part is high except for 90 minutes and 240 minutes. The optimal time may be 90 minutes or 240 minutes, and S5 performance may be accompanied for the remaining times.

Experimental Example 7 - Checking the effects of melting at different levels and S6, S7, and S8

In order to overcome the difference confirmed in Experimental Example 6, as shown in Fig. 9, the molten metal can be discharged at the level of the controlled middle part by changing the height of the discharge port during discharge by dividing it by the level of the molten metal.

An example of this is shown in Table 10.

<Table 10>

Sample 1 of Table 4, 50 tons made through S1 and S2, was melted at 750℃ in type 1 melting furnace, 250 kg of S0 additive 4 was added, S4 was performed for 120 minutes, S5 was performed, S6 was performed for 60 minutes (Experiment 1), S6 was performed for 120 minutes (Experiment 2), and S6 temperature was 850℃. As shown in Fig. 9, the molten metal was discharged at the level of the middle part where Ti was controlled by changing the height of the discharge port at the time of discharge by dividing it by the level of the molten metal. After S6, stirring (S7) was performed to increase the temperature for discharge again, and then discharge was performed. The dross removal part of S8 can be omitted, but it can be confirmed that there is a removal effect of some Ti when the dross is removed. Since most of the dross and the surfaced Ti are removed in S5, it can be proceeded directly to S9.

The experimental results showed that when we did S4, S6, and then S7 again, we got better results than when we did only S4 and S6.

Experimental Example 8 - Confirmation of the effects of S6, S7, and S8

Experiment A was conducted from S1 to S4, Experiment B from S1 to S6, and Experiment C from S1 to S7, and then the water was drained. The results of analyzing the reactants of each experiment are shown in Table 11.

<Table 11>

The common experimental conditions were to use the reflector TYPE of Fig. 2, and to make 50 tons of molten metal using Sample 4 of Table 4 through S1 and S2, at which time the S3 atmosphere temperature was 1,100℃, the molten metal temperature was 900℃ at S3, the S4 method was EMS, the S4 speed was 80 rpm, the S4 time was 210 minutes, and in S0, 250 kg of additive 3 was evenly sprinkled throughout the melting furnace in solid type. S5 was performed twice with a total of 500 kg each, and a separate dross was used to separate the ash and metal, recover the metal, and recycle the ash. S6 was performed for 90 minutes, and S7 was performed for an additional 4 hours. At this time, the casting temperature at the time of discharge was 740℃.

Even if the molten metal temperature is over 900℃, the outlet of the hot water bath does not have a heat retention function and is heated with a torch, etc. to a temperature of 200~300℃. Therefore, the temperature at the time of outlet drops to a minimum of 100℃ and a maximum of 250℃, which is indicated as the outlet temperature. In other words, the outlet temperature is the same as the molten metal temperature.

As shown in the results in Table 11, Experiment C was able to increase the removal rate by approximately 7% more than Experiment A.

Experimental Example 9 - Injection of S0 into the tank

Fig. 6 shows the appearance of the discharge channel for discharging molten metal from the furnace. The discharge channel appearance is described in detail here. The depth of the discharge channel is approximately 400 mm, the width is 300 mm, and the total length is more than 3 m. When C1 is opened, the molten metal is discharged through C2. To prevent hunting of Ti in the C3 section during the discharge and to obtain a constant chemical composition, S0 (additive) is added in the C3 section. Since the production is continuous, the molten metal flows through the discharge channel and the flow rate is 1.3 to 5 m ³ /s, but it was fixed to 1.3 m ³ /s in the experiment. Considering the amount of Ti in the molten metal discharged from C2, the flow rate per minute, and the flow rate, S0 was added at 1 kg every 10 minutes.

As shown in Table 12, the experimental results showed that a constant component level of less than 50 ppm could be obtained.

<Table 12>

From this, it can be seen that Ti can be removed by removing the product precipitated in the C6 section at regular intervals, as shown in Fig. 7, by the phenomenon in which the product is accumulated by the section-wise partition (C11) inside the heater and the rest are cast.

S0 can be supplied by being injected into the tank as a wire type or by being supplied in a divided manner (for example, 1g each). There is no separate mixing, and it can be mixed into the molten metal at the flow rate of the tank. However, it can also be supplied continuously.

According to the present invention, transition metal impurities in molten aluminum that adversely affect the decrease in electrical conductivity can be removed with an efficiency of 90% or more based on titanium by adding an appropriate boron alloy (aluminum boron master alloy) without facility investment or process change. This enables the input of raw materials containing a small amount of transition metal in the high-purity aluminum manufacturing industry, especially in the wire aluminum manufacturing industry or the high-purity steelmaking raw material manufacturing process, thereby expanding the spectrum of raw material use and further reducing costs, making it an environmentally friendly technology due to the reduction in indirect _CO2 emissions.

Currently, there is no general technology for controlling trace elements such as Ti in molten aluminum, and thus physical separation is relied on. Although the usability has been confirmed through previous research results, there are no cases of applying processes such as boron treatment in actual operations. The present invention is a method for manufacturing an aluminum deoxidizer for electrical steel sheets having Ti <50 ppm or less and for manufacturing an aluminum alloy.

This allows for a groundbreaking reduction in _CO2 emissions by replacing primary ingots with 100% scrap by controlling impurities in molten aluminum, thereby replacing the use of primary ingots.

Claims (11)

In a method for controlling impurities in molten aluminum scrap, A step of melting a metal material including aluminum scrap to form a molten metal and an impurity remover including boron; A step of forming a reactant by reacting at least a portion of the impurities contained in the metal material in the molten metal with the boron; and A step of separating the reactant from the molten metal is included. The above impurities include transition metals, The above transition metal comprises at least one of titanium, chromium, vanadium and zirconium, The above reactant is in the form of MB ₂ , where M is the transition metal, A method wherein the above impurity remover is an alloy of boron and the above aluminum. In the first paragraph, The above boron alloy contains 1 to 20 wt% boron, additional components and the remainder aluminum, The above additional component comprises at least one of chromium, titanium, vanadium and zirconium, A method wherein the weight of the above additional component is 0.2 to 1.5% of the weight of boron. In the first paragraph, The step of separating the reactants from the molten metal is: A step of first stirring the above molten metal; A first dross removal step for removing dross after the first stirring; A step of precipitating the reactant within the molten metal after the first dross removal; A step of stirring the molten metal a second time after the above precipitation; and A method comprising a second dross removal step of removing dross after the second stirring. In the third paragraph, A method in which the above precipitation is performed for 30 minutes to 8 hours. In paragraph 4, A method in which the temperature of the molten metal during the above precipitation is 850 to 950°C. In the first paragraph, The formation of the above molten metal and the formation and removal of the above impurities are performed in a melting furnace. After removal of the above impurities, A step of discharging the molten metal from the above melting furnace into a hot water tank; and A method further comprising the step of adding an impurity remover to the molten metal in the above bath. In Article 6, A method in which the above impurity remover is applied to the molten metal flowing in a straight direction without stirring from the outside of the melting furnace. In Article 7, A method in which the impurity removing agent added to the molten metal in the above bath is 0.5 g to 2.0 g per kg of the molten metal. In Article 7, A method in which the amount of impurity remover added to the molten metal in the above-mentioned bath is 8% to 30% of the amount of impurity remover supplied to the molten metal in the melting furnace per molten metal weight. In Article 9, The above-mentioned bath includes a spout, an upstream bath, a pond, a middle bath, a heating furnace, and a downstream bath, which are arranged sequentially along the direction of progression of the molten metal. A method in which the above impurity remover is supplied to the above upstream tank. In Article 10, The above pond is a method in which the vertical cross-sectional area in the direction of progression of the molten metal is 3 to 30 times that of the above upstream tank.

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