Method for controlling impurities in molten aluminum scrap

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

[0001] The present invention relates to a method for appropriately controlling impurity elements other than aluminum contained in aluminum scrap in order to recycle aluminum scrap and use it by dividing it by grade according to its appropriate use.

[0002] Aluminum is manufactured and used in various ways. Currently, the most common method of producing aluminum is to obtain aluminum ingots (primary ingots) through beneficiation, smelting, and refining of bauxite. The second method is to collect aluminum scrap and remelt it for reuse. The former method generates CO2, various chlorine (Cl2) gases, and red mud during aluminum manufacturing. Specifically, while 16.5 tCO2eq of CO2 is generated per ton of aluminum ingot, using aluminum scrap produces zero CO2 from the raw materials used, and the remaining 0.5-0.7 tCO2eq is derived from the energy fuel used to operate the melting furnace, resulting in a significant CO2 reduction.

[0003] 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 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.

[0004] 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.

[0005] The purpose of the present invention is to provide a method for controlling impurities in molten aluminum scrap.

[0006] The above object of the present invention is achieved by a method for controlling impurities in a molten aluminum scrap, comprising the steps of: melting a metal material including aluminum to form a molten aluminum and an impurity remover including boron; reacting at least a portion of the impurities contained in the metal material with the boron in the molten aluminum to form a reactant; and 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 MB2, wherein M is the transition metal, and the impurity remover is an alloy of boron and the aluminum.

[0007] The 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 may be 0.2 to 1.5 wt% of the weight of boron.

[0008] 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 within 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.

[0009] The above precipitation can be performed for 30 minutes to 8 hours.

[0010] The temperature of the molten metal during the above precipitation may be 850 to 950°C.

[0011] 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 to a runner may be further included; and the step of injecting an impurity remover into the molten metal in the runner may be further included.

[0012] The above impurity remover can be applied to the molten metal flowing in a straight direction without stirring from the outside of the melting furnace.

[0013] 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.

[0014] The amount of impurity remover added to the molten metal in the above 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.

[0015] The above-mentioned bath includes a spout, an upstream bath, a pond, a middle bath, a heating furnace, and a downstream bath, which are sequentially arranged along the direction of progression of the molten metal, and the impurity remover can be supplied to the upstream bath.

[0016] 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 larger than that of the above upstream tank.

[0017] For scrap, accurate physical sorting of grades 1,000 to 9,000 is challenging. While UBCs (Used Beverage Cans, hereinafter referred to as "UBCs"), which account for the largest portion of scrap, are somewhat sorted, considering operational efficiency, it's more advantageous to use mixed scraps to manufacture aluminum deoxidizers and alloys for steelmaking.

[0018] The present invention provides a method for controlling impurities in the process of manufacturing an aluminum deoxidizer and alloy using collected aluminum scrap.

[0019] Figure 1 is a flowchart of an impurity control method according to one embodiment of the present invention.

[0020] Figures 2 and 3 show the melting furnace type used in the experimental example.

[0021] Figure 4 is a schematic diagram of a cross-section of a sample obtained in an experimental example.

[0022] Figure 5 is a schematic diagram of a cross-section of the molten metal in an experimental example.

[0023] Figure 6 shows the tank used in Experimental Example 7.

[0024] Figure 7 is a plan view of the heating furnace in Experimental Example 7.

[0025] The present invention relates to a deoxidizer for high-purity steelmaking and impurity control for manufacturing an alloy using aluminum of the 1,000 to 9,000 series, but is not limited thereto.

[0026] 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 types thereof vary depending on the type of scrap.

[0027] Weight %

[0028]

[0029] 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.

[0030] The following description primarily 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. Furthermore, while the removal of impurities is primarily exemplified by the removal of titanium, the present invention is not limited thereto.

[0031] In the following description, % means weight % unless otherwise stated.

[0032] 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.

[0033] First, aluminum scrap (1,000-9,000 series) is sorted and stored by type. In particular, foreign materials such as steel cans and steel columns are sorted and sorted, while foreign materials such as wood and film are sorted (S1).

[0034] Scrap is mixed appropriately based on aluminum for each raw material, targeting the deoxidizer (S2).

[0035] Next, it goes through the melting process (S3). At this time, to prevent heat energy loss 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.

[0036] The melting temperature may be 700°C to 1300°C when using radiant heat, or 550°C to 870°C or 650°C to 900°C when using direct heat. The melting time may take 1 to 8 hours depending on the mass to be melted.

[0037] 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 added in a solid state. In continuous operation, a method of placing the additive in an additive tank and injecting it into a melting furnace can be used.

[0038] 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.

[0039] In Fig. 2, each instruction 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 burner, and 204 for the atmosphere.

[0040] In Fig. 3, each instruction number indicates 2 as a melting furnace, 100 as an additive, 101 as an additive tank, 103 as an additive injection port, 200 as an aluminum molten metal, 204 as an atmosphere, 300 and 301 as an impeller, and 304 as a spout port.

[0041] S0 may be an aluminum-boron alloy. The boron alloy may comprise 0.1 to 20 wt% or 0.1 to 5 wt% boron and the remainder aluminum.

[0042] Boron in S0 forms an intermetallic compound with aluminum, specifically, AlB2 or AlB 12 It can be in the form AlxByM1z with a third element (additional component) M1 in addition to aluminum and boron.

[0043] M1 contains V, Ti, Cr, Zr, etc. as shown in Table 2, and it is also possible to use a material in which Ti is not present at all. The weight of M1 may be 0.2 to 1.5% or 0.2 to 0.4% of the weight of B.

[0044] Table 2

[0045]

[0046] 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.

[0047] Alternatively, the amount of S0 used can be adjusted to 0.0005 to 1.2 times, 0.002 to 0.08 times, based on the weight ratio of the metal material (aluminum scrap).

[0048] When the solution is first stirred (S4) in a molten state, the transition metal (M) and boron react to form a reactant.

[0049] An example of the formation of a reactant (MB2) is as shown in Equation 1 below.

[0050] Equation 1> AlB2(s,l) + M(l) → Al(l) + MB2(S)

[0051] Formula 2> AlB 12 (s,l) + M(l) → Al(l) + MB2(S)

[0052] AlB2 or AlB that did not react at this time 12 To increase the number of effective collisions, the molten metal is stirred or ultrasonically treated.

[0053] The first stirring can be performed at 100 rpm to 400 rpm for 30 minutes to 8 hours or 3 hours to 5 hours.

[0054] 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.

[0055] 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.

[0056] The next process is the first dross removal process, which removes the dross generated after stirring and reaction of S0. (S5)

[0057] At this time, impurities can be removed more effectively by injecting an inert gas into the molten metal. The use of an inert gas is useful when manufacturing an alloy. + , and oxides can be removed to improve castability.

[0058] S6 is a step for precipitating the reactants after stirring. This is done to increase the particle size of TiB2 through precipitation and to facilitate removal of precipitated substances from the bottom. In addition, by providing precipitation time, the reaction time of Ti and B can be increased.

[0059] 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.

[0060] After the sedimentation time, the second stirring (S7) is performed again, and the Ti that was not able to react at the top reacts with B once again, and in the process, TiB2 floats up as dross (S8, secondary dross removal). Dross removal is performed because floating the precipitated material is easier for production than removing it. After this, S9 is tapped and cast.

[0061] Secondary stirring can be performed at 100 rpm to 400 rpm for 30 minutes to 8 hours or 3 hours to 5 hours.

[0062] 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.

[0063] Finally, the most crucial aspect of continuous production is ensuring that aluminum products maintain a consistent chemical composition. The present invention manufactures products with a consistently low impurity content by adding S0 (S10) once more to the melting pot during discharging.

[0064] 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 discharged. 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.

[0065] 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.

[0066] The tank, especially the upper tank, may be a trench-shaped tank with a cover provided at the top. S0 may be introduced into the upper part of the molten metal by opening a portion of the cover or by providing an inlet in the cover.

[0067] The molten metal into which S0 is injected in the upstream tank flows in one direction without separate stirring. Here, the one direction may be a straight line.

[0068] The reason for pouring into the upper water tank is that the water flow rate at the outlet is fast and the water flow rate at the upper water tank is relatively stable.

[0069] The pond is designed to handle overflow. It can be two to five times the width and length of the upstream tank. The reaction between Ti and B primarily occurs within the pond.

[0070] In other embodiments, stirring may be applied to the pond to increase the reaction rate.

[0071] The reaction product of Ti + B accumulates in a space at the bottom of the furnace and can be periodically removed.

[0072] There is a mesh (or ceramic filter) at the bottom of the filter zone to filter out impurities.

[0073] The present invention is described in more detail through the following experimental examples.

[0074] Experimental Example 1 - S0 input type

[0075] 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.

[0076] Table 3

[0077]

[0078] 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 of 25℃. The reaction conditions were a temperature of 780℃, a stirring speed of 200 rpm, an amount of 500 kg of aluminum raw material, and 1 kg 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, scrap 1, scrap 2, and scrap 5 were applied to manufacture aluminum deoxidizer molten metal sample 1, and scrap 4, scrap 6, scrap 8, scrap 9, and scrap 10 were applied to manufacture aluminum deoxidizer molten metal sample 2, and an experiment was conducted.

[0079] Weight %

[0080]

[0081] Experimental results show that the Ti concentration in the liquid form reacts more quickly. However, the initial reaction rate is significantly affected, and similar results are observed after a certain period of time, but the initial reaction rate is significantly improved.

[0082] Experimental Example 2 - S0 Type

[0083] S0 can be of the form AlxByM1z with a third element M1 other than aluminum and boron, examples of which are as follows.

[0084] 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, melting for 1 hour, 7.5g of S0 added, followed by S4 for 2 hours and S6 for 4 hours. At this time, the initial Ti content in the melt was 244ppm. The main conditions at this time were: no S0 added, additive 4 in the AlxByM1z form of Table 2, 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 bath. In order to confirm the precipitation of TiB2 and CrB2 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 in Fig. 4 and analysis was performed. At this time, the cross-section was divided into six equal parts, and all surfaces were cut into grids to conduct analysis, dividing them into upper (①, ②), middle (③, ④), and lower (⑤, ⑥). Component analysis was conducted using ICP and S-OES, and the Ti precipitates at the bottom were analyzed using OM / SEM / EDS.

[0085] The analysis results are shown in Table 5, and when additives 4 and 5 were used, the Ti removal rates were compared, and the two results were similar. Additive 4, in the AlxByMz form, had a Ti removal rate of 74.5%, and additive 5, in the AlxBy form, had a Ti removal rate of 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 remove it as CrB2, and the Cr removal rate was confirmed to be approximately 42.4 to 43.2%.

[0086] Table 5

[0087]

[0088] In the case of the lower part of ⑦ in Fig. 5, the Ti content was 2,900 ppm, and it was confirmed through ICP results that a large amount of Ti was precipitated. It was confirmed that Ti, Cr, and V were concentrated in the lower part, 300 μm or less.

[0089] Experimental Example 3 - Stirring Time and Dross Removal

[0090] Table 6 shows the experimental results for Ti control according to stirring time.

[0091] 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.

[0092] 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, 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.

[0093] Table 6

[0094]

[0095] Ti removal according to stirring time showed 89~90% Ti control effect at 240 minutes. Stirring can be done using EMS, EMP, and agitator equipment. EMS (Electromagnetic stirrer) is an indirect stirring method that uses a magnetic field to make the material rotate in the direction of the magnetic field. EMP (Electromagnetic pump) refers to a method of stirring using a pump by adding and removing the molten metal using a liquid pump. The agitator uses an impeller, and both EMS and EMP methods can be used in melting furnace 1, but only agitator and EMP methods can be used in melting furnace 2.

[0096] Experimental Example 4 - Dross Removal

[0097] Since some aluminum is bound to be released into the dross, this dross can be used in a separate process to recover aluminum metal.

[0098] In order 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.

[0099] Experimental Example 5 - Injection of inert gas during stirring

[0100] 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 the melting furnace type 2 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 with Ar gas (25 LPM). S7 was performed for 1 hour, and S9 was performed without going through S8.

[0101] Table 7 shows the results of the analysis of Ti.

[0102] Table 7

[0103]

[0104] After calculating and analyzing all the amounts, it was found that 37.2% of Ti could be removed by flotation, and the remaining 40% was removed by sedimentation, resulting in a total removal rate of 72.7%. This confirms that some Ti can be flotated and removed through stirring alone. By removing the dross 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.

[0105] The most important factors in precipitation are temperature and time. When performing S6, the temperature can range from 680 to 950°C or 720 to 770°C. Higher temperatures, such as 850 to 950°C, can actually hinder precipitation by causing some TiB2-type compounds to float to the surface rather than assisting the aluminum precipitation reaction.

[0106] Experimental Example 6 - Temperature and Time of Precipitation Reaction

[0107] The optimal conditions for temperature and time of the precipitation reaction were confirmed. 200 kg of sample 1 in Table 4, prepared through S1 and S2, was melted at 750°C 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°C.

[0108] Table 8 shows the average results of analyzing the upper, middle, and lower parts of the sample after the reaction.

[0109] Table 8

[0110]

[0111] As a result, the sedimentation time showed a sedimentation removal rate of over 90% at 90 and 240 minutes. As shown in Fig. 8, when observing the lower part at 90 and 240 minutes using SEM, it was confirmed that the lower sediment layer was formed and sedimented. At 240 minutes, the size increased further and formed a T-shape. In addition, except for 90 and 240 minutes, the results of analyzing the samples after the experiment showed that there were differences between the sections.

[0112] Table 8 shows the average analyzed by dividing the melt into levels as in Fig. 9, and Table 9 shows that when the precipitation temperature is 900℃, from 30 minutes to 240 minutes, levels 90 or higher are marked as the upper part, or “upper”, and levels less than 30 are marked as the lower part, or “lower” in the levels of Fig. 9. When the precipitation temperature is 850℃ or higher, if the precipitation is performed for more or less 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 the dross and remove Ti together. Alternatively, only the middle level of 30 to 90% can be used.

[0113] Table 9

[0114]

[0115] The results in Table 9 confirm that the Ti concentration is high in the upper part, except at 90 and 240 minutes. The optimal time may be 90 or 240 minutes, and S5 may be performed during the remaining time periods.

[0116] Experimental Example 7 - Checking the effects of melting at different melting levels and S6, S7, and S8

[0117] 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 level of the molten metal.

[0118] An example of this is shown in Table 10.

[0119] Table 10

[0120]

[0121] 50 tons of sample 1 of Table 4, which was made through S1 and S2, was melted at 750℃ in furnace type 1, 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 was performed at 850℃. As shown in Fig. 9, the molten metal was divided into levels and the height of the tapping hole was changed during tapping, so that the molten metal was tapped at the level of the controlled middle part. After S6, stirring (S7) was performed to increase the temperature for tapping again, and then tapping was performed. The dross removal part of S8 can be omitted, but it can be confirmed that some Ti is removed when the dross is removed. Since most of the dross and the floated Ti are removed in S5, S9 can be proceeded directly.

[0122] The results of the experiment showed that when we did S4, S6, and then S7 again, we got better results than when we did only S4 and S6.

[0123] Experimental Example 8 - Confirming the effects of S6, S7, and S8

[0124] 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 removed. The results of analyzing the reactants of each experiment are shown in Table 11.

[0125] Table 11

[0126]

[0127] 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, and the S4 time was 210 minutes. For S0, 250 kg of additive 3 was evenly distributed throughout the melting furnace in the solid type. S5 was performed twice in total at 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℃.

[0128] Even if the molten metal temperature is over 900℃, the outlet of the outlet has no heat retention function and is heated with a torch or the like to a temperature of 200-300℃. Therefore, the temperature drops to a minimum of 100℃ and a maximum of 250℃ when the outlet is opened, which is indicated as the outlet temperature. The outlet temperature is the same as the molten metal temperature.

[0129] As shown in the results in Table 11, Experiment C was able to increase the removal rate by approximately 7% more than Experiment A.

[0130] Experimental Example 9 - Injection of S0 into the tank

[0131] Figure 6 shows the appearance of the discharge channel for discharging molten metal from the melting furnace. The appearance of the discharge channel is described in detail. The discharge channel depth 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 to C2. During the discharge, S0 (additive) is added to the C3 section to prevent hunting of Ti and to obtain a constant chemical composition. Since the production is continuous, the molten metal flows in the discharge channel, and the flow rate is 1.3 to 5 m. 3 / s or 1.3m in the experiment 3 / s was fixed and implemented. Considering the amount of Ti in the molten metal discharged from C2 and the flow rate and volume per minute, S0 was injected at 1 kg at 10-minute intervals.

[0132] As a result of the experiment, it was possible to obtain a constant component of less than 50 ppm, as shown in Table 12.

[0133] Table 12

[0134]

[0135] From this, it can be seen that Ti can be removed by removing the products precipitated in the C6 section at regular intervals, as shown in Fig. 7, by the phenomenon in which the products are accumulated by the section-by-section partitions (C11) inside the furnace and the remaining products are cast.

[0136] S0 can be supplied by wire injection into the tank or by dividing it into a fixed amount (e.g., 1 g each). There is no separate mixing required, and it can be mixed into the molten metal at the tank's flow rate. However, it can also be supplied continuously.

[0137] According to the present invention, transition metal impurities in molten aluminum that adversely affect the reduction of electrical conductivity can be removed with an efficiency of over 90% 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 small amounts of transition metals in the high-purity aluminum manufacturing industry, especially in the wire aluminum manufacturing process or the high-purity steelmaking raw material manufacturing process, thereby broadening the spectrum of raw material use and further reducing costs, making it an environmentally friendly technology due to the reduction in indirect CO2 emissions.

[0138] Currently, there is no general technology for controlling trace elements such as titanium in molten aluminum, relying instead on physical separation. While previous research has confirmed its usability, there have been no practical applications of processes such as boron treatment. The present invention provides a method for manufacturing an aluminum deoxidizer for electrical steel sheets containing less than 50 ppm of titanium and for manufacturing aluminum alloys.

[0139] This allows for a revolutionary reduction in CO2 emissions by replacing the primary ingot with 100% scrap by controlling impurities in the molten aluminum and replacing the primary ingot usage.

Claims

1. 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 MB2, where M is the transition metal, A method wherein the above impurity remover is an alloy of boron and the above aluminum.

2. In paragraph 1, 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.

3. In paragraph 1, 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.

4. In paragraph 3, A method in which the above precipitation is performed for 30 minutes to 8 hours.

5. In paragraph 4, A method in which the temperature of the molten metal during the above precipitation is 850 to 950°C.

6. In paragraph 1, 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.

7. In paragraph 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.

8. In paragraph 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.

9. In paragraph 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.

10. In paragraph 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.

11. In paragraph 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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