RU2361941C2 - Method of ligature receiving aluminium-scandium, flux for ligature receiving and device for method implementation - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes high-temperature exchange reaction of fluoride or oxide of scandium with aluminium in medium of molten metal halogenides. Aluminium is melted in drops form, received by means of its filtration, they are passed through molten metal halogenides by means of exhaustion creation, received melt is isolated then it is discharged metal halogenides melt and formed aluminium-scandium melt. It is used flux, containing aluminium fluorides, fluoride or oxide of scandium, fluoride and chloride of calcium and if necessary hydro-fluoride or potassium fluoride at following components correlation, wt %: calcium fluoride 10-35, aluminium fluoride 2-10, scandium fluoride 2-20, or scandium oxide 2-8, hydro- fluoride or potassium fluoride 0-5, calcium chloride is the rest. Device contains lined melting pot, heater and additional second melting pot, located over the first and allowing perforated bottom, if necessary coated by one or two layers of graphitised fabric, herewith both melting pots are located in waterproof tank, allowing in bottom part hole, connected to backing vacuum pump, and located into resistance furnace.

EFFECT: high purity of end product by admixture of sodium along with high extraction scandium into it.

3 cl, 10 ex, 6 tbl

Description

The invention relates to the field of metallurgy of non-ferrous metals and can be used for the production of aluminum-scandium alloys used for the modification of aluminum alloys.

A known method of producing an aluminum-scandium ligature, comprising a high-temperature exchange reaction of fluoride or scandium oxide with aluminum in a medium of molten metal halides, namely in the presence of scandium fluoride, potassium chloride, sodium fluoride or scandium oxide, aluminum fluoride, sodium fluoride and potassium chloride or fluoroscandi alkaline or alkaline-earth element and potassium or sodium chloride using a coating flux containing potassium chloride and sodium chloride in the temperature range of 850-1050 ° C with an exposure of 15-30 min t (RF patent №2213795, MCI S22S 1/00, 2003).

A flux is known for producing an aluminum-scandium ligature by means of a high-temperature exchange reaction of fluoride or scandium oxide with aluminum containing, as a substance containing scandium fluoride, an alkali or alkaline earth metal fluoroscandiate and potassium or sodium chloride (RF patent No. 1549091, MKI C22C 1 / 2, 1999).

A disadvantage of the known process, as well as the flux for the implementation of this process, is the use of sodium salts, which in the process of high-temperature exchange reactions fall into the resulting aluminum alloy. It is known from experimental data (Lozhkin LN, Popov AP "Investigations of the cathodic process in the electrolysis of cryolite-alumina melt." Sat. Physical chemistry and electrochemistry of molten salts and slags. Ed. Chemistry, L., 1968. S. 303-311), that in a sodium cryolite-alumina electrolyte with a cryolite ratio (co.) Of 2.80, a joint discharge of aluminum and sodium cations begins. The current efficiency of aluminum begins to fall, and the more noticeable, the higher the r.p. An admixture of sodium impairs the properties of aluminum and its alloys, and also increases the hydrogen content (Table 1).

Sodium, hydrogen and cold rolling force values (R _F )

Table 1 Sodium ^10-4 % 0 5 thirty 82 The hydrogen content, 10 ^-4 % 0.20 0.40 0.52 0.48 The value of the value of R _F , N / mm ² 350 370 485 630

As a result, during pressure treatment of aluminum containing increased amounts of sodium, the waste of the foil significantly increases due to its marriage. In domestic technical conditions for aluminum-scandium alloys TU 11-01-01-2001, the content of the alkaline component is not limited, unlike the requirements of foreign companies. Usually the sodium content in the Al-2% Sc ligature

(3 ÷ 7) · 10 ^-3 %. This is primarily due to the use of sodium salts in the preparation of ligatures.

The second factor causing the contamination of the final product with sodium impurities is the use of aluminum grade A85 (99.85% Al) or granulated aluminum grade ChDA (TU 6-09-02-529-92) with a basic substance content of 99.9% in the process of producing aluminum scandium ligatures.

In addition, it should be noted that in the production of aerospace aluminum alloys, high quality requirements are imposed on the quality of the ligature in terms of uniformity of chemical composition in the volume of castings, high purity in the content of non-metallic inclusions, porosity and the absence of large (coarse) aluminide particles.

A device is known for producing a scandium-containing master alloy containing a sealed reactor placed in a shaft furnace (RF patent No. 2261924, C22B 5/04, 2005).

A disadvantage of the known device is the use for the ligature of aluminum grade A85 (99.85% Al) or granular aluminum grade ChDA (TU 6-09-02-529-92) with a basic substance content of 99.9%. In this case, the starting aluminum of grade A85 contains sodium 0.0074 ± 0.0022 wt.% And grade ChDA contains 0.0035 ± 0.0008 wt.%) Sodium, which leads to sodium contamination of the final product.

Thus, the authors were faced with the task of developing a method for producing an aluminum-scandium alloy, providing a high purity of the final sodium product along with a high level of scandium extraction into the alloy.

The problem is solved in a method for producing an aluminum-scandium alloy, including the melting of aluminum and flux to obtain a metal halide melt and the implementation of a high-temperature exchange reaction of fluoride or scandium oxide with aluminum in a medium of molten metal halides, in which a flux containing aluminum fluoride, fluoride or oxide is used scandium, fluoride and calcium chloride, and potassium hydrofluoride or potassium fluoride in the following ratio of components, wt.%:

calcium fluoride - 10-35; aluminum fluoride - 2-10; scandium fluoride - 2-20; or scandium oxide -2-8; hydrofluoride or potassium fluoride - 0-5; calcium chloride - the rest,

the molten aluminum is filtered to obtain droplets and passed through molten metal halides by creating a vacuum, the melt is held, then the metal halide melt is drained and the aluminum-scandium alloy formed.

The problem is also solved by using flux to obtain an aluminum-scandium alloy, containing scandium fluoride or oxide and aluminum fluoride, which additionally contains calcium fluoride and chloride and potassium hydrofluoride or fluoride in the following ratio, wt.%:

calcium fluoride -10-35; aluminum fluoride - 2-10; scandium fluoride - 2-20; or scandium oxide -2-8; hydrofluoride or potassium fluoride - 0-5; calcium chloride - the rest.

The problem is also solved by using a device for producing an aluminum-scandium alloy, containing a lined crucible and a heating device, which further comprises a second crucible located above the first and having a hole bottom, optionally covered with one or two layers of graphite fabric, and both crucibles are located in a sealed container having an opening in the lower part connected to a foreline pump and placed in a resistance furnace.

At present, there is no known method for producing an aluminum-scandium alloy by high-temperature exchange reaction of fluoride or scandium oxide with aluminum, in which molten aluminum in the form of droplets obtained by its filtration is passed through molten metal halides by creating a vacuum, and the flux of the proposed one is used as a flux composition.

To improve the quality of ligatures, the authors propose filtering liquid aluminum into the corresponding molten salt. In the work, we used initial grade A85 aluminum containing 0.0074 ± 0.0022 wt.% Sodium and ChDA grade containing 0.0035 ± 0.0008 wt.% Sodium. The studies were carried out in crucibles made of borosilicon graphite grade BSG-30 (density not less than 2.2 g / cm ³ , TU 48-20-72-90). The upper crucible with a hole bottom was covered with graphitized material (fabrics TMP-4, TGN-2M, TMP-3 or felt VIT-1). For all types of these fabrics and felt, the results were obtained on a significant (2-10 times) removal of sodium from aluminum under the accepted filtering conditions: temperature 750-850 ° C and the inclusion of vacuum up to 10 ^-2 mm Hg from the foreline pump (table 2).

table 2 Experimental data on the change in the sodium content in aluminum when filtered through graphitized materials Filter material The sodium content, wt.% Source aluminum Filtered Aluminum TMP-4 0.0075 ± 0.0022 0.0028 ± 0.0008 0.0073 ± 0.0002 0.00068 ± 0.00002 TGN-2M (2 layers) 0.0077 ± 0.0023 0.0040 ± 0.0015 0.0040 ± 0.0015 0.00044 ± 0.000013 TMP-3 0.0078 ± 0.0023 0.0038 ± 0.0011 0.0038 ± 0.0011 0.0008 ± 0.00002 Note: Samples were taken: source (I) aluminum from the melt immediately after the melting of aluminum; filtered (P) aluminum after hardening and cooling.

The durability and performance of a filter made of graphitized carbon materials was checked by repeated filtering of aluminum through the same filter. In laboratory conditions, 10 heats were performed on a filter from two layers of TGN-2M fabric (Table 3).

Table 3 The dependence of the purification of grade A85 aluminum from sodium by filtration through two layers of TGN-2M fabric on the number of filtrations Number of filtrations through the same filter one 2 3 four 5 6 7 8 9 10 And · 10 ³ 3.8 4.0 3.5 3.0 3.7 3.4 3.1 3.6 3.7 3.3 P · 10 ⁴ 4.0 4.4 3.7 2.9 4.1 3.3 3.5 3.7 3.9 3.8 P 9.5 9.1 9.4 10.3 9.0 10.3 8.8 9.7 9.5 8.7 Note: I, P - see table 2; P is the reduction in sodium in the number of times.

Therefore, to reduce the sodium content in the starting aluminum, it is necessary to use a melt filtering process, optionally through graphite fabric, for example, TGN-2M. Filtration also reduces the suspension content in the melt, traps oxide films enriched in impurities, and it is very important that the contact surface of aluminum (droplets) with the salt melt increases sharply. The latter circumstance accelerates the occurrence of high-temperature exchange reactions between aluminum and dissolved salt.

The salt composition proposed by the authors, used as a flux, does not contain sodium salt. The authors propose a composition based on calcium chloride and fluoride, a binary diagram of which was studied by W. Plato (Plato W. Zeitshritt für Physikaalische Chemia. Leipzig, 1907. S.530-372). The eutectic is 86.2% CaCl ₂ and 13.8% CaF ₂ and has a melting point of 644.4 ° C. The liquidus temperature gradually increases to a composition with 35.5% CaF ₂ having a temperature of 750 ° C. It is impossible to use a binary composition in the indicated range from the eutectic to the peritectic CaCl ₂ · CaF ₂ reaction at 750 ° C without data on the solubility of the corresponding scandium fluorides and oxides, the conditions for the high-temperature exchange reaction, the achievement of a high conversion of scandium from salt to the ligature, and coagulation of individual drops of metallic melt into an ingot. The measurements of the properties of salt compositions performed on a TG-DTA-92 thermal analyzer are presented in Table 4.

Table 4

Liquidus temperature (tl, ° С), crystallization onset (tcr, ° С) and supercooling value (Δt, ° С) of salt compositions based on chloride (CaCl ₂ ) and calcium fluoride (CaF ₂ ), wt.% No. CaCl ₂ CaF ₂ Scf ₃ Sc ₂ O ₃ Alf ₃ KF (KHF ₂ ) * tl tcr Δt one 87 13 - - - - 647 618 29th 2 83 17 - - - - 644 626 eighteen 3 87 13 2.5 - - - 653.5 642.7 10.8 four 87 13 5.0 - - 722 694 28 5 83 17 10.0 - - - 716 680 36 6 83 17 2.0 - - 5.0 704 684 twenty 7 83 17 5.0 - - 5.0 703 675 28 8 83 17 10.0 - - 3.7 706 684 22 9 83 17 - - - 3.7 717 682 35 10 83 17 10.0 - 5.0 * 738 709 29th eleven 83 17 10.0 - 10.0 - 709 696 13 12 83 17 - - 10.0 - 736.6 706.2 30.4 13 83 17 - - 5.0 - 727 705 22.0 fourteen 83 17 - 2.0 - 5.0 709 660 49.0 fifteen 83 17 - 5.0 - 5.0 710 655 55 16 83 17 - 5.0 - 5.0 * 693 662 31 17 78 22 - 10.0 - 10.0 * 692 663.7 28.3 eighteen 83 17 - - - 7.4 693 671 22 19 83 17 - - - 10.0 * 700 676.6 23.4 twenty - - - - - 100.0 857.3 852.6 4.7 21 - - - - - Kcl 737 720 17.0 Note: The values for the pure salts KF (No. 20) and KCl (No. 21) are consistent with tabular data on their melting points. Additives SCF ₃ , SC ₂ O ₃ , AlF ₃ , KF (or KHF ₂ ) are indicated in wt.% Of the weight of calcium salts.

The introduction of the proposed flux of aluminum fluoride salt (AlF ₃ ) is due to the high refining ability of fluoride in relation to aluminum melts, which favors the coalescence of droplets in the molten salt into an ingot. The latter fact is confirmed by visual observation. Introduction to the composition of the proposed flux acidic potassium fluoride (hydrofluoride) potassium (KHF ₂ ) due to its ability to melt at 239 ° C and decompose in the temperature range 400-500 ° C. Upon decomposition of KHF ₂ , hydrogen fluoride is released, which helps to remove traces of moisture. Moisture present in the salt system leads to hydrogenation of the ligature.

Not trusting the semiquantitative determination of the solubility of scandium fluoride and oxide in salts according to the Van Goff law, due to a certain shift in the composition of salts due to the volatility of calcium chloride (vapor pressure 1 mmHg at 1100 ° C), we determined the solubilities of scandium compounds in recommended to obtain the ligature salt compositions (table 5).

Table 5 The solubility of fluoride and scandium oxide in a molten salt of CaCl ₂ + CaF ₂ depending on temperature, wt.% Temperature ° C 850 900 1000 1100 Scf ₃ 6.0 7.7 > 14.7 Sc ₂ O ₃ 2.5 - 5.37 9.5

Note: According to DTA, scandium oxide dissolves at temperatures above 740 ° C. Solubility data was obtained by holding the salt mixture in a closed platinum crucible at a temperature of 1100 ° C for 30 minutes, then holding it for one hour at the selected temperature and then pipetting the upper layer of the melt for chemical analysis for scandium.

The introduction of potassium fluoride or acid potassium fluoride (KHF ₂ ) on the solubility of the scandium salt is probably little affected. Potassium tetrafluoroscandiate (KSCF ₄ ) melts at 810 ° C, and the compound KSC ₂ F ₇ decomposes into KSCF ₄ and SCF ₃ at temperatures above 826 ° C (Sobolev B. P. The rare earth trifluorides. Pt. 1. The light temperature chemistry of the rare earth trifluorides. Barselona. Spain: Institute d'Estudis Catalans, 2000; Sokolova Yu.V., Cherepanin PH, Sagalova TB Izv. VUZov. Non-ferrous metallurgy, 2006. No. 2. P.40-44. )

The proposed flux based on CaCl ₂ + CaF ₂ has a significantly lower volatility compared to fluxes based on NaF + KCl, especially at temperatures above 850 ° C:

Composition, wt.% Temperature ° C Volatility · 10 ⁴ , g / cm ² · min 70CaCl ₂ + 30CaF ₂ 850/950 0.8 / 3.2 90CaCl ₂ + 10CaF ₂ 850/950 1.4 / 4.8 67CaCl ₂ + 21CaF ₂ + 12ScF ₃ 850/950/1000 2.6 / 7.9 / 15.8 65CaCl ₂ + 17CaF ₂ + 8AlF ₃ + 10ScF ₃ 850/950/1000 2.4 / 8.8 / 17.0 70KCl + 12NaF + 18ScF ₃ 850/950 18.6 / 28.5 67KCl + 18NaF + 10AlF ₃ + 5Sc ₂ O ₃ 850/950/1000 18.0 / 32.0 / 52.8

The definition of sodium in the ligature is presented in table.6.

Table 6 Sodium Ligature Ingot Element,
wt.% Granulated aluminum PSA (A999), not filtered A85, filtered A999, filtered one 2 3 four 5 6 7 Na10 ⁴ 8.6 4.7 3.2 3.3 3.5 2.8 2.7 Note: No. 1 ligature obtained according to the patent of the Russian Federation No. 2213795, No. 2-7 - by the proposed method.

The proposed quantitative limits for the salt content in the flux are explained by the following reasons. A calcium fluoride content of less than 10 wt.% Leads to a decrease in the solubility of scandium oxide, an increase in the entrainment of calcium chloride as a more volatile component, and also precipitation of β phase crystals (the melting point of pure calcium chloride is 773 ° C). A calcium fluoride content of more than 35 wt.% Leads to the precipitation of the CaCl ₂ · CaF ₂ solid phase at 750 ° С, and the liquidus temperature in this binary system further increases sharply (melting point CaF ₂ ≈1400 ° C). An aluminum fluoride content of less than 2 wt.% Affects the degree of fusion of liquid metal droplets. Thus, the absence of aluminum fluoride in the salt mixture causes poor fusion of the liquid droplets of the alloy into a common mass, in this case, along with the ingot, individual alloy granules are obtained, which ultimately reduces the degree of scandium extraction into the ligature (see Example 10). An increase in its content of more than 10 wt.% Is undesirable due to the high consumption and increased entrainment due to its volatility (the vapor pressure of pure aluminum fluoride at 950 ° C is 1 mmHg). A scandium fluoride content of less than 2 wt.% Leads to a decrease in metallurgical yield and a lower content of scandium in the ligature (<1.5% Sc). An increase in the content of more than 20 wt.% Leads to the appearance of a solid phase and possible losses during the discharge of the molten salt. A scandium oxide content of less than 2 wt.% Does not provide a standard ligature (Al2% Sc). A scandium oxide content of more than 8 wt.% Is undesirable, since a significant portion of this oxide remains insoluble under the conditions of the process and leads to unnecessary losses.

A device for implementing the method of obtaining the ligature of aluminum-scandium is shown in the drawing. The device comprises a crucible lined with borosilicate graphite (1) for aluminum. The crucible (1) has a hole bottom (4), for example, the bottom can be provided with through holes (4) with a diameter of 3.0-3.5 mm in increments of 10-15 mm, arranged in parallel diametrical rows. The hole bottom is optionally covered with one or two layers of graphitized material (3). As graphitized material can be used fabrics TMP-4, TGN-2M, TMP-3 or felt VIT-1. The crucible (5) for the melt of halide salts, which receives the filtrate from the crucible (1), is located under the crucible (1), and both crucibles (1) and (5) are placed in a sealed container (6) made of stainless steel. The tank (6) is equipped with a resistance furnace (7) and has an opening (9) in the lower part connected to the foreline pump.

The proposed method can be implemented as follows. A flux is prepared to produce an aluminum-scandium alloy, containing calcium fluoride and chloride, aluminum fluoride, scandium fluoride or oxide and optionally potassium hydrofluoride within the proposed mass content of the components, by mixing well-dried starting salts. A mixture of salts is placed in a crucible (5). An aluminum ingot is placed in a crucible (1) having a hole bottom (4), which is optionally coated with one or two layers of graphite fabric (3). They turn on the heating and, upon reaching a temperature of 850-900 ° C, turn on a fore-vacuum pump to create a vacuum in the volume of the sealed container (6). After molten aluminum in the form of droplets obtained by filtering it through the hole in the bottom of the crucible (1) enters the crucible (5), the obtained melt is kept for 10 min at a temperature of 850-900 ° С. After exposure, the molten salt is poured into a crucible, and liquid aluminum is poured into a cast iron mold coated to prevent contamination with hexagonal boron nitride. The cooled ingot of aluminum alloy (ligature) is washed from the salt residues in a vibration bath with weak hydrochloric acid (1-5%), marked and analyzed. The content of scandium in the salt mass is also determined.

The proposed method is illustrated by the following examples.

Example 1. A mixture of dried salts is prepared: 35 g of CaCl ₂ (58.3 wt.%), 16 g of CaF ₂ (26.7 wt.%), 6 g of AlF ₃ (10 wt.%), 3 g of ScF ₃ ( 5 wt.%). The mixture is stirred and triturated in a mortar. Then placed in a BSG-30 crucible (⌀60, h 80, S ~ 8 mm). An aluminum ingot (A85) weighing 51 g is placed in a crucible mounted on top, the bottom of which has openings of 03.5 mm in increments of 15 mm and is covered with graphite fabric TGN-2M, weighing 51 g. Upon reaching a temperature of 850 ° C, the container in which the crucibles are placed is connected to fore-vacuum pump. After aluminum enters the lower crucible, the aluminum melt in the salt melt is held for 10 minutes. Then, the molten salt is poured into a crucible, and the liquid aluminum alloy is poured into a cast iron mold coated to prevent contamination with hexagonal boron nitride (BN).

The cooled ingot of aluminum alloy (ligature) is washed from the residual salts in a vibration bath with weak hydrochloric acid (1-5%), marked and analyzed. The content of scandium in the salt mass is also determined.

The following results were obtained:

The initial Sc content in the salt mixture (calculated) is 1.32 g.

The final salt content is 0.26 g.

Content in ligature 2.15% Sc.

Received ligatures - 49.5 g.

In total, 0.0215 · 49.5 = 1.06 g or 80.6% of the original went into the ligature.

Example 2. The method is carried out as described in example 1, but to obtain a melt of halide salts using a larger crucible (crucible brand BSG-30 (ǿ100, h 80, S ~ 10 mm ² ). The composition of the initial flux: 35 g CaCl ₂ ( 63.0 wt.%), 15 g of CaF ₂ (27.0 wt.%), 1.5 g of AlF ₃ (2.0 wt.%), 4.5 g of ScF ₃ (8.0 wt.%) ), and aluminum grade A85 was taken in an amount of 100 g. The exposure time at 850 ° C after filtering the molten aluminum is 10 minutes.

The following results were obtained:

In the initial mixture of scandium salts - 1.98 g.

The content of scandium in the ligature is 1.8%.

0.018 × 98.5 = 1.78 g Sc.

Remained in salt (including losses) 0.21 g Sc.

The direct yield of scandium alloy was 89.8%.

Example 3. The method is carried out as described in example 1. The composition of the starting flux: 46 g of CaCl ₂ (66.2 wt.%), 20 g of CaF ₂ (28.8 wt.%), 2 g of AlF ₃ (3 wt. %), 2.5 g of ScF3 (2.0 wt.%), And aluminum (A85) take 50 g. The exposure after filtering aluminum at 850 ° C through a TGM-2 fabric is 10 min.

The following results were obtained:

The initial mixture of scandium salts was 0.98 g.

The content of Sc in the alloy is 1.7%.

0.017 × 46.5 = 0.79 g Sc.

The direct yield to the alloy was 80.7%.

Example 4. The method is carried out as described in example 1. The composition of the starting flux: 35 g of CaCl ₂ (54.7 wt.%), 15 g of CaF ₂ (23.4 wt.%), 5 g of AlF ₃ (7.8 wt.%), 3.2 g of KHF ₂ (5.0 wt.%), 4.0 g of ScF ₃ (6.5 wt.%) and aluminum (A85) - 90 g. The exposure time at 850 ° C after filtration is 10 minutes.

The following results were obtained:

The scandium content in the alloy is 1.75%.

0.017 × 87 = 1.48 g Sc.

Direct exit of scandium to the ligature - 84%.

Example 5. The method is carried out as described in example 2. The composition of the starting flux: 30 g of CaCl ₂ (62.6 wt.%), 10 g of CaF ₂ (20.8 wt.%), 2.3 g of AlF ₃ (4 , 9 wt.%), 2 g of KF ₂ (4.9 wt.%), 3.7 g of Sc ₂ O ₃ (8.0 wt.%) (2.41 g of Sc), and aluminum (A85) was taken 92 g. at 850 ° C is 10 minutes.

The following results were obtained:

The content of Sc in the alloy is 2.15%.

Received ligatures 89.5 g.

In the ligature of scandium 0.021589.5 = 1.93 g.

Direct yield of scandium - 79.8%.

Example 6. The method is carried out as described in example 5. The composition of the starting flux: 45 g of CaCl ₂ (80.9 wt.%), 5.6 g of CaF ₂ (10 wt.%), 2.5 g of AlF ₃ (4.5 wt. %), 3.7 g of KF (3.7 wt.%), 2.5 g of ScF ₃ , (4.5 wt.%), And aluminum (A85) were taken 52 g. The exposure time at 900 ° C is 20 minutes.

The following results were obtained:

The starting salt contained 1.10 g Sc. The Sc content in the alloy is 1.92%.

The ligature content is 0.019 × 48.0 = 0.91 g Sc.

Direct yield of scandium - 82.7%.

Example 7. The method is carried out as described in example 3. The composition of the starting flux: 23 g of CaCl ₂ (46 wt.%), 17 g of CaF ₂ (34 wt.%), 10 g of ScF ₃ (20 wt.%), 2.5 g AlF ₃ (2.5 wt.%) and aluminum grade ChDA was taken 150 g. Filtering is carried out using a single layer of graphite fabric TGM-2, exposure at 800 ° C for 15 minutes.

The following results were obtained:

The starting salt contained 4.41 g of Sc.

The content of Sc in the alloy is 2.6%.

The content in the ligature is 0.026 · 147 = 3.83 g Sc.

Direct access to the ligature - 86.7%.

The sodium content in the ligature 2.7 · 10 ^-4 %.

Example 8. The process is carried out in large crucibles (grade BSG-30, ǿ 120, h 140, S 15 mm), on the hole bottom of the crucible placed graphite fabric TGN-2M in two layers. Flux composition: 54 g of CaCl ₂ (35 wt.%), 10 g of AlF ₃ (6.5 wt.%), 20 g of ScF ₃ (13 wt.%), 70 g of CaCl ₂ (45.5 wt.%) and aluminum grade A85 taken 400 g. Exposure at 850 ° C is 15 minutes.

The following results were obtained:

The initial mixture of scandium salts was taken 8.82 g.

The content of Sc in the alloy is 2.02%.

Ligatures obtained 393 g.

The scandium ligature content was 0.0202 × 393 = 7.94 g Sc.

Direct yield of scandium - 90%.

The sodium content in the initial A85 was 3.5 · 10 ^-3 %, in the sodium ligature 3.5 · 10 ^-4 %.

Example 9. The method is carried out as described in example 3. The composition of the flux: 30 g of CaF ₂ (30 wt.%), 9 g of AlF ₃ (9 wt.%), 2 g of ScF ₃ (2 wt.%), 59 g CaCl ₂ (59 wt.%). ChDA granulated aluminum was taken 50 g. The exposure time at 800 ° C is 15 minutes.

The following results were obtained:

0.88 g was taken in the initial mixture of scandium salts

The content of Sc in the alloy is 1.6%.

Received ligatures 48 g

Scandium is contained in the ligature 0.016 · 48 = 0.768 g.

Direct yield of scandium - 87.3%.

Example 10. The method is carried out as described in example 1. The composition of the starting flux: 35 g CaCl ₂ (63.6 wt.%), 5 g ScF ₃ (9.1 wt.%). Exposure at 850 ° C is 10 minutes.

The absence of aluminum fluoride in the initial flux led to poor fusion of liquid alloy droplets into a total mass. Along with ingots 5 granules of alloy were obtained (the size of a pea). To determine the chemical composition of the ligature, the ligature was remelted in the absence of salts.

The following results were obtained:

The initial content of SCF ₃ in salt (calculated) is 9.1%.

The final salt content is 2.40%.

Content in ligature 2.85% Sc.

In total, 0.0285 · 58.0 = 1.65 g Sc was transferred to the ligature, which amounted to 75.1% of the original.

Thus, the authors propose a method for producing an aluminum-scandium ligature, a flux for producing this ligature, and a device for implementing the proposed method, which ensure high purity of the final product by sodium impurity along with high extraction of scandium into it.

Claims (3)

1. A method of producing an aluminum-scandium alloy, comprising melting aluminum and flux to produce a metal halide melt and performing a high-temperature exchange reaction of fluoride or scandium oxide with aluminum in a molten metal halide medium, characterized in that they use a flux containing aluminum fluoride, fluoride or oxide scandium, fluoride and calcium chloride and potassium hydrofluoride or potassium fluoride in the following ratio of components, wt.%:
calcium fluoride 10-35 aluminum fluoride 2-10 scandium fluoride 2-20 or scandium oxide 2-8 potassium hydrofluoride or potassium fluoride 0-5 calcium chloride rest
in this case, molten aluminum is filtered to obtain droplets and passed through molten metal halides by creating a vacuum, the melt is held, then the metal halide melt is drained and the aluminum-scandium alloy formed. 2. The flux to obtain the aluminum-scandium alloys containing fluoride or scandium oxide and aluminum fluoride, characterized in that it additionally contains fluoride and calcium chloride and potassium hydrofluoride or potassium fluoride in the following ratio, wt.%:
calcium fluoride 10-35 aluminum fluoride 2-10 scandium fluoride 2-20 or scandium oxide 2-8 potassium hydrofluoride or potassium fluoride 0-5 calcium chloride rest 3. A device for producing an aluminum-scandium alloy, containing a lined crucible and a heating device, characterized in that it further comprises a second crucible located above the first and having a hole bottom, optionally coated with one or two layers of graphite fabric, both crucibles in a sealed container having in the lower part an opening connected to a foreline pump and placed in a resistance furnace.