Scandium additive production and use method

Abstract

The invention discloses a scandium additive production and use method, and relates to the technical field of aluminum alloy production, and the scandium additive production and use method specifically comprises the following steps: mixing: firstly, fully mixing scandium oxide powder and scandium fluoride which are strictly proportioned, adding a cosolvent for secondary fine mixing, and hot-pressing the scandium oxide powder and scandium fluoride mixture subjected to secondary fine mixing into blocks, and crushing and screening the hot-pressed material blocks, screening the crushed blocks or crushed materials, and packaging and warehousing the particles as qualified products. According to the method, the production process optimization of the scandium additive and the alloying addition of the scandium additive are realized; and finally, the process and the technology are optimized from scandium additive production to scandium additive use, so that the purposes of high quality, high efficiency and high cost performance are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy production, in particular to a method for producing a scandium additive and a method for using the same. Background Art

[0002] Scandium is a soft, silvery-white metallic element with a certain degree of activity. When exposed to air, scandium oxide (Sc2O3) forms on its surface, gradually changing its color from silvery-white to light yellow or pink. Its density is approximately 2.985-2.99 g / cm 3 ; Its melting point is 1541℃ and boiling point is 2836℃. It has high melting point and boiling point and can remain stable under certain high temperature environment. Metal scandium has a 3d structure and is in the same period as transition metal elements Ti, V, and Cr. At the same time, it is in the same family as rare earth elements La, Ce, Pr, Nd, etc. Scandium has the beneficial effects of these two types of metals in aluminum alloys, and the effect is far better than these two types of metals. Therefore, it has received widespread attention and application in recent years. Adding 0.4% scandium to aluminum alloy will increase the alloy strength by 30%, and its weldability is also significantly improved. At the same time, its heat resistance and corrosion resistance are also significantly improved.

[0003] The high specific strength and high temperature performance of aluminum-scandium alloys make them widely used in various fields such as aerospace, transportation, marine engineering, national defense and military industry, and new energy.

[0004] Scandium is a rare and rare earth amphoteric metal with extremely high chemical activity and a high melting point (1539℃), while the melting point of aluminum is very low (660℃). This brings great difficulties to the smelting and manufacturing of aluminum-scandium master alloys. At present, the methods for producing aluminum-scandium alloys can be roughly divided into four categories with a total of nine methods: for example, three melt thermal reduction methods: such as the doping method (using metallic scandium as raw material); vacuum aluminothermic reduction method (using ScF3 as raw material and aluminum as reducing agent); mixed reduction method (using Sc2O3 as raw material and liquid aluminum as reducing agent); and briquetting method (using Sc2O3 as raw material, Using aluminum powder as reducing agent); alloy method (using ScCI3 as raw material and Mg in Al-Mg alloy as reducing agent); also includes electrolysis method, such as: KCI-ScCI3 molten salt electrolysis method (using ScCI3 as raw material); Sc2O3-ScF3-3NaF﹡AIF3 system molten salt electrolysis method (using Sc2O3 as raw material); Sc2O3-ScF3-LiF system molten salt electrolysis method (using Sc2O3 as raw material); Sc2O3-ScF3-NaF system molten salt electrolysis method (using Sc2O3 as raw material), etc.

[0005] The characteristics of the scandium chloride molten salt aluminum-magnesium thermal reduction method are as follows: Sc2O3 is first dissolved in hydrochloric acid, and then Sc2O3, NaCl, KCl, and NH4Cl are mixed in proportion. The mixture is then vacuum dehydrated and dehydrated at medium temperature to produce anhydrous scandium chloride molten salt. Then, industrial pure aluminum and industrial pure magnesium are heated and melted in proportion, and anhydrous scandium chloride molten salt and specific additives are added. After smelting, the mixture is taken out of the furnace and cast to obtain an aluminum-magnesium-scandium master alloy.

[0006] Aluminothermic reduction method: Using scandium oxide extracted from titanium dioxide wastewater and tungsten slag as raw material, aluminum ingots as reducing agent, and a special solvent, aluminothermic reduction is carried out at 950°C under non-vacuum conditions. After heat preservation, pouring, and surface treatment, high-quality aluminum-scandium alloy is produced. This method is simple and reliable, with low impurity content and a scandium direct recovery rate of >90%.

[0007] Scandium fluoride metallothermic reduction method: Scandium fluoride is first prepared, and then metallothermic reduction is performed; however, the preparation of scandium fluoride requires the use of highly toxic hydrogen fluoride, the equipment is complex, and the metallothermic reduction temperature is also very high;

[0008] Molten salt electrolysis method: The equipment is complex, the conversion rate is not high, and it has high requirements for equipment, making it difficult to scale up production.

[0009] The above four categories, totaling nine aluminum-scandium alloy production methods, demonstrate that molten salt electrolysis and metallothermic reduction are the most worthy of serious research and promotion. However, there is considerable disagreement regarding which of these two methods is superior, particularly regarding process maturity and stability. Ultimately, the goal should be to pursue simple, pollution-free, low-cost, and high-quality processes and methods.

[0010] Therefore, based on the above, we need a method for producing and using a scandium additive to solve the above problems. Summary of the Invention

[0011] The purpose of the present invention is to provide a method for producing and using a scandium additive to solve the problems raised in the above background technology.

[0012] To achieve the above object, the present invention provides the following technical solutions:

[0013] A method for producing a scandium additive comprises the following steps:

[0014] Step 1: Mixing: First, thoroughly mix the strictly proportioned scandium oxide powder and scandium fluoride, and add a solvent for secondary fine mixing;

[0015] Step 2: Hot pressing: hot pressing the scandium oxide powder and scandium fluoride mixture that have undergone secondary fine mixing into blocks;

[0016] Step 3: Crushing: crush the hot pressed blocks;

[0017] Step 4: Screening: Screen the scandium additive fragments or crushed materials and package and store the particles that meet the granular shape (3-6mm) as qualified products.

[0018] Another object of the present invention is to provide a method for using a scandium additive: the specific steps include: adding the scandium additive directly to a melting furnace or to a holding furnace; before adding the scandium additive, first sampling and analyzing the charge; and according to the analysis results,

[0019] Calculate the amount of non-scandium additives and the amount of scandium additives added.

[0020] As a further solution of the present invention: the optimal dosage and calculation method of the scandium additive include: assuming that the aluminum liquid weighs 10,000 kg (10 tons) and contains 0.00% scandium in the aluminum liquid (analysis before melting), the scandium in the aluminum liquid is adjusted to 0.1%, then (0.1~0.00)%×10,000÷5%÷95%=210.5 kilograms, where 5% is the scandium content in the scandium additive, and 95% is the actual recovery rate of scandium in the scandium additive.

[0021] As a further solution of the present invention: after calculating the amount of non-scandium additives and the amount of scandium additives to be added, when the temperature of the aluminum liquid rises to 750±5°C, the slag on the surface of the aluminum liquid is scraped off, and various blocky non-scandium additives are first added to the aluminum molten pool, and then the scandium additives are sprayed into the aluminum molten pool.

[0022] As a further solution of the present invention, the aluminum liquid after adding the scandium additive is allowed to stand for 20-30 minutes, then vigorously stirred for 10-15 minutes, and then allowed to stand for 5-10 minutes, sampled and analyzed, and transferred to the next production link after the composition is qualified.

[0023] Compared with the prior art, the beneficial effects of the present invention are: the present invention solves the optimization of the production process of aluminum-scandium alloy and the optimal process parameters for the alloying addition of scandium additives, that is, ultimately optimizes the process and technology from the production of scandium additives to the use of scandium additives, achieving the goals of high quality, high efficiency and high cost performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A process flow chart for the production of a scandium additive and its use method;

[0025] Figure 2 This is the phase diagram of Al-Sc alloy. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Scandium additive production equipment:

[0028] Batching equipment:

[0029] Function: Accurately weigh and proportion scandium salt and other raw materials (such as scandium oxide powder, scandium fluoride powder, solvent, etc.) to ensure that the ingredients meet the requirements.

[0030] Selection: Common ones include electronic scales and batching systems. Electronic scales are used to accurately weigh the weight of raw materials, and batching systems can automatically complete the batching of multiple raw materials according to preset recipes, improving the accuracy and efficiency of batching.

[0031] Mixing equipment:

[0032] Function: Mainly used for uniform mixing of scandium oxide powder, scandium fluoride powder and solvent powder to achieve reasonable chemical composition requirements (including uniformity of chemical composition content).

[0033] Model Selection: Common mixing equipment includes three-dimensional motion mixers, V-type mixers, double-cone mixers, and planetary mixers. Generally, a three-dimensional motion mixer is preferred. Its unique three-dimensional motion allows the mixing drum to simultaneously translate, rotate, and oscillate in three directions, creating a complex motion trajectory within the drum for uniform mixing. This provides excellent mixing performance, effectively preventing powder agglomeration and segregation. The mixing process is gentle, with minimal impact on powder size and shape. The equipment is also simple to operate and clean.

[0034] Powder hot pressing equipment:

[0035] Function: Mainly used for hot pressing of scandium oxide powder, scandium fluoride powder and flux powder. In a certain pressure and temperature environment, the mixed powder is densified and formed under high temperature and high pressure.

[0036] Model selection: A hot press is primarily composed of a frame, heating system, pressurization system, and control system. The frame supports and secures the components; the heating system typically uses resistance heating or induction heating to quickly heat the mold and powder to the set temperature; the pressurization system provides pressure through hydraulic or mechanical devices to compact the powder in the mold; and the control system precisely controls parameters such as temperature, pressure, and dwell time.

[0037] Crushing equipment:

[0038] Function: Used to crush the scandium additives that are hot pressed into blocks.

[0039] Type: Continuous ball mill is used. The ball mill bushing and grinding balls are made of high-purity corundum to ensure that there will be no secondary pollution during the processing.

[0040] Screening equipment:

[0041] Function: Classify by particle size, screen out qualified granular products (3-6mm), and remove fine powder or oversized particles. Type: Utilizes a continuous vibrating screener. Qualified granular products are discharged from the discharge port and packaged. Fine powder is returned to the raw material batching system for reuse, while oversized particles are returned to the continuous ball mill for further crushing.

[0042] Operation precautions:

[0043] Precise batching: Precise batching according to the scandium additive formula;

[0044] Strict mixing: uniform mixing to achieve reasonable chemical composition requirements;

[0045] Hot pressing: Control the heating temperature, pressure and holding time to ensure complete reaction and consistent performance of hot pressed blocks.

[0046] Ball milling: The amount of grinding balls added should be stable to reduce energy consumption.

[0047] Vibrating screening: Replace damaged screen in time.

[0048] The specific steps include:

[0049] Step 1: Mixing: First, thoroughly mix the strictly proportioned scandium oxide powder and scandium fluoride, and add a solvent for secondary fine mixing;

[0050] Step 2: Hot pressing: hot pressing the scandium oxide powder and scandium fluoride mixture that have undergone secondary fine mixing into blocks;

[0051] Step 3: Crushing: Crushing the hot-pressed block of scandium oxide powder and scandium fluoride mixture into fragments or scraps;

[0052] Step 4: Screening: Screen the scandium additive fragments or crushed materials and package and store the particles that meet the granular shape (3-6mm) as qualified products.

[0053] like Figure 2As shown, since Sc has the smallest atomic radius among all rare earth elements, the main alloying particle ScAl3 has a high melting point and is close to Al, so it is easy to form a supersaturated solid solution during the crystallization process, and coherent ScAl3 particles are easily precipitated during heating and extrusion, thereby strongly inhibiting the recrystallization process and improving the stability of the alloy. Precisely because of this, its liquidus line is close to and steeper than aluminum, so the aluminum-scandium alloy cannot have a higher scandium content than other aluminum master alloys, such as Al-Sr, Al-RE, and Al-Li alloys. For conventional Al-Sc master alloys, the Sc concentration is 2-8%.

[0054] Scandium additives general composition table

[0055] Product Name model Scandium content density Appearance Scandium additives MTT-5Sc 5％ 2.4-2.5g / cm Granular (3-6mm), white

[0056] Scandium additives are white, granular (3-6mm) metal particles with a density of 2.4-2.5g / cm3 and a melting point of around 650-700℃, which is not much different from pure aluminum and is conducive to processing and forming under certain temperature conditions.

[0057] Best way to use scandium additives:

[0058] ① Scandium additives can be added directly to the melting furnace or to the holding furnace, but must be added before refining;

[0059] ② After all the charge is melted, stir vigorously and take samples for analysis;

[0060] ③ Based on the analysis results, calculate the amount of non-scandium additives and scandium additives added.

[0061] ④ When the temperature of the aluminum liquid rises to 750±5℃, scrape off the slag on the surface of the aluminum liquid, first add various blocky non-scandium additives (such as iron, copper, manganese, etc.) into the aluminum molten pool, and then spray the scandium additives into the aluminum molten pool.

[0062] ⑤ Let it stand for 20-30 minutes, then stir vigorously for 10-15 minutes, let it stand for another 5-10 minutes, and take samples for analysis;

[0063] ⑥After the ingredients are qualified, they can be transferred to the next process.

[0064] Optimal dosage and calculation method of scandium additives:

[0065] Assume that the weight of the aluminum liquid is 10,000 kg (10 tons) and the scandium content in the aluminum liquid is 0.00% (analysis before melting). If you want to adjust the scandium content in the aluminum liquid to 0.1%, then (0.1~0.00)%×10,000÷5%÷95%=210.5 kg, where 5% is the scandium content in the scandium additive and 95% is the actual recovery rate of scandium in the scandium additive.

[0066] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Although this specification describes the embodiments, not every embodiment contains only one technical solution. This description is for clarity only. Those skilled in the art should read the specification as a whole. The technical solutions in the various embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for producing a scandium additive, characterized in that: The specific steps include: Step 1: Mixing: First, thoroughly mix the strictly dosed scandium oxide powder and scandium fluoride, and add a solvent for secondary fine mixing; Step 2: Hot pressing: hot pressing the scandium oxide powder and scandium fluoride mixture that have undergone secondary fine mixing into blocks; Step 3: Crushing: Crushing the hot-pressed block of scandium oxide powder and scandium fluoride mixture to form scandium additive fragments or scraps; Step 4: Screening: Screen the scandium additive fragments or crushed materials and package and store the particles that meet the granular shape (3-6mm) as qualified products.

2. A method for using a scandium additive, according to the method for producing a scandium additive according to claim 1, characterized in that: Before adding the scandium additive, the charge is first sampled and analyzed, and the amount of non-scandium additive and scandium additive added is calculated based on the analysis results.

3. The method for using a scandium additive according to claim 2, characterized in that: The optimal dosage and calculation method of the scandium additive include: assuming that the aluminum liquid weighs 10,000 kg (10 tons) and contains 0.00% scandium in the aluminum liquid (analysis before melting), the scandium in the aluminum liquid is adjusted to 0.1%, then (0.1~0.00)%×10,000÷5%÷95%=210.5 kilograms, where 5% is the scandium content in the scandium additive, and 95% is the actual recovery rate of scandium in the scandium additive.

4. The method for using a scandium additive according to claim 3, characterized in that: After calculating the amount of non-scandium additives and scandium additives to be added, when the temperature of the aluminum liquid rises to 750±5℃, scrape off the slag on the surface of the aluminum liquid, first add various blocky non-scandium additives into the aluminum molten pool, and then spray the scandium additives into the aluminum molten pool.

5. The method for using a scandium additive according to claim 4, characterized in that: It also includes letting the aluminum liquid after adding the scandium additive stand for 20-30 minutes, then vigorously stirring it for 10-15 minutes, and then letting it stand for 5-10 minutes, taking samples for analysis, and then transferring it to the next production link after the composition is qualified.

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