Potassium fluoroaluminate type iron agent and its preparation method and aluminum alloy

Abstract

This application belongs to the technical field of elemental additives for cast aluminum alloys, specifically a potassium fluoroaluminate type iron agent, its preparation method, and an aluminum alloy. The potassium fluoroaluminate type iron agent disclosed in this application is characterized by comprising: stearic acid; reduced iron powder, wherein the mass fraction of iron in the reduced iron powder is ≥98.5%; potassium fluoroaluminate, wherein the potassium fluoroaluminate and reduced iron powder are pressed and bonded together by stearic acid to form the potassium fluoroaluminate type iron agent; wherein the density of the potassium fluoroaluminate type iron agent is ≥3.7 g / cm³, and the mass fraction of iron in the potassium fluoroaluminate type iron agent is 73%-77%.

Description

Technical Field

[0001] This application relates to the field of elemental additives for cast aluminum alloys, specifically to a potassium fluoroaluminate type iron agent, its preparation method, and an aluminum alloy. Background Technology

[0002] There are currently two methods for adding iron in the preparation of iron-containing aluminum alloys: one is by adding Al-Fe master alloys, and the other is by adding traditional powdered iron additives. Because Al-Fe master alloys have a high melting point, the melting time of Al-Fe master alloys is long during the aluminum alloy preparation process, resulting in high energy consumption. Furthermore, the melting of Al-Fe master alloys produces a significant amount of slag, leading to fluctuations in the actual iron recovery rate. Traditional powdered iron additives are prone to moisture absorption and oxidation, resulting in severe burn-off during master alloy smelting, leading to low iron recovery, excessive slag, and high levels of production dust. Additionally, powdered iron additives themselves have poor stability and a short shelf life. Summary of the Invention

[0003] This application provides a potassium fluoroaluminate-type iron agent, its preparation method, and an aluminum alloy. By combining reduced iron powder with an iron content ≥98.5% by mass and potassium fluoroaluminate-type iron agent with an iron content of 73%-77% by mass, the required iron content can be stably provided for aluminum alloy smelting, ensuring the iron recovery rate meets the standards. The density of the potassium fluoroaluminate-type iron agent ≥3.7 g / cm³ can suppress the oxidation and burn-off of the potassium fluoroaluminate-type iron agent after it is added to the aluminum melt, thus maintaining a stable iron recovery rate in the potassium fluoroaluminate-type iron agent.

[0004] In a first aspect, embodiments of this application provide a potassium fluoroaluminate type iron agent, comprising: stearic acid; reduced iron powder, wherein the mass fraction of iron in the reduced iron powder is ≥98.5%; potassium fluoroaluminate, wherein the potassium fluoroaluminate and the reduced iron powder are pressed together by the stearic acid to form the potassium fluoroaluminate type iron agent; wherein the density of the potassium fluoroaluminate type iron agent is ≥3.7 g / cm³, and the mass fraction of iron in the potassium fluoroaluminate type iron agent is 73%-77%.

[0005] In one possible implementation, the thickness of the potassium fluoroaluminate type iron agent is 20mm-25mm.

[0006] In one possible implementation, the stearic acid has a mass fraction of 0.2%-0.3%, based on the mass of the potassium fluoroaluminate iron agent.

[0007] Secondly, embodiments of this application also provide an aluminum alloy comprising the potassium fluoroaluminate-type iron agent provided in the first aspect of this application.

[0008] Thirdly, embodiments of this application provide a method for preparing a potassium fluoroaluminate-type iron agent. This method is used to prepare the potassium fluoroaluminate-type iron agent provided in the first aspect of this application. The preparation method includes: weighing reduced iron powder, stearic acid, and potassium fluoroaluminate according to a preset mass ratio of reduced iron powder to stearic acid and potassium fluoroaluminate, wherein the mass of iron element in the reduced iron powder accounts for 73%-77% of the total mass of the weighed stearic acid, reduced iron powder, and potassium fluoroaluminate; mixing and stirring the stearic acid, the reduced iron powder, and the potassium fluoroaluminate to obtain a mixed powder; pressing the mixed powder under a first pressure range and a first pressing time to obtain a cake of a target weight; and allowing the cake to stand for a first standing time under a preset environment to cool the cake to room temperature to obtain the potassium fluoroaluminate-type iron agent.

[0009] In one possible implementation, the stearic acid includes at least one of magnesium stearate, barium stearate, and sodium stearate.

[0010] In one possible implementation, mixing and stirring the stearic acid, the reduced iron powder, and the potassium fluoroaluminate includes: adding the stearic acid, the reduced iron powder, and the potassium fluoroaluminate into the barrel of a mixer; controlling the barrel to rotate at a speed of 5 r / min-8 r / min, and controlling the stirring blades of the mixer to rotate at a speed of 25 r / min-35 r / min within the barrel; wherein the ratio of the rotational speed of the stirring blades to the rotational speed of the barrel is ≥4:1.

[0011] In one possible implementation, the first pressure range is 14MPa-18MPa; and / or the first pressing duration is 2s-4s.

[0012] In one possible implementation, the relative humidity of the preset environment is ≤40%RH; and / or the wind speed of the preset environment is 0.5m / s-1m / s; and / or the first settling time is ≤30min.

[0013] In one possible implementation, the preparation method further includes: wrapping the obtained potassium fluoroaluminate type iron agent with an aluminum foil of a target thickness.

[0014] The potassium fluoroaluminate-type iron agent, its preparation method, and the aluminum alloy provided in this application embodiment are achieved by selecting reduced iron powder with an iron content ≥98.5% by mass, and combining it with potassium fluoroaluminate and stearic acid to press it into a potassium fluoroaluminate-type iron agent with a density ≥3.7 g / cm³. The high purity of the reduced iron powder and the potassium fluoroaluminate-type iron agent with a density ≥3.7 g / cm³ reduce the probability of introducing iron oxide into the potassium fluoroaluminate-type iron agent, thereby reducing the generation of slag and dust when the potassium fluoroaluminate-type iron agent is added to the aluminum melt, and thus stabilizing the iron recovery rate to ≥96%. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is one of the schematic flowcharts for preparing potassium fluoroaluminate type iron agents provided in the embodiments of this application; Figure 2 This is a second schematic diagram of the process for preparing potassium fluoroaluminate type iron agent provided in the embodiments of this application; Figure 3 This is the third schematic diagram of the process for preparing potassium fluoroaluminate type iron agent provided in the embodiments of this application. Detailed Implementation

[0017] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings. In the drawings, for clarity, the dimensions of layers, regions, and elements, as well as their relative dimensions, may be exaggerated. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0018] It should be noted that the terms "first," "second," etc., used in this application's specification are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0019] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0020] In the preparation of iron-containing aluminum alloys, there are currently two main methods for adding iron: the Al-Fe master alloy addition method and the traditional powdered iron addition method. Both methods have technical defects and are difficult to meet the needs of efficient and high-quality industrial production.

[0021] Firstly, when using the Al-Fe master alloy addition method, the high melting point of the Al-Fe master alloy, far exceeding the conventional smelting temperature of aluminum alloys, necessitates a significant amount of heat to complete the melting process after its addition to the molten aluminum. This prolonged melting time not only significantly increases energy consumption during aluminum alloy preparation but also extends the production cycle and reduces production efficiency. Furthermore, during the melting process, the Al-Fe master alloy readily reacts with oxygen in the melt, generating a large amount of alumina dross. This dross adsorbs some iron elements and is discharged with the dross, leading to large fluctuations in the actual iron recovery rate. This makes it difficult to control the iron content in the aluminum alloy, affecting the stability of the alloy's microstructure and mechanical properties.

[0022] Secondly, when using the traditional method of adding powdered iron, the large surface area and high activity of the powdered iron make it highly susceptible to moisture absorption and oxidation during storage and use. This results in poor stability, a short shelf life, and difficulty in long-term storage. During aluminum alloy smelting, the oxidized powdered iron is burned off at high temperatures, preventing a large amount of iron from incorporating into the melt. This not only leads to a low iron recovery rate but also generates a large amount of slag and dust due to the oxidation reaction, polluting the melt and the production environment. It increases the workload of the slag removal process, reduces production efficiency, increases production costs, and simultaneously affects the purity and performance consistency of the aluminum alloy products.

[0023] The potassium fluoroaluminate type iron agent in the embodiments of the first aspect of this application includes stearic acid, reduced iron powder and potassium fluoroaluminate.

[0024] The main component of reduced iron powder is elemental iron, with a high iron content (≥98.5% by mass) and low impurity content. The elemental iron in reduced iron powder serves as the iron source for potassium fluoroaluminate-type iron agents. Thus, potassium fluoroaluminate-type iron agents prepared from reduced iron powder with an iron content ≥98.5% have fewer impurities, reducing the proportion of impurities introduced into the aluminum alloy, lowering the probability of structural defects, and resulting in good mechanical properties. Simultaneously, the high iron content in reduced iron powder reduces oxidation loss in the potassium fluoroaluminate-type iron agent, thereby reducing slag formation and dust emissions. The iron content in potassium fluoroaluminate-type iron agents prepared from reduced iron powder is 73%-77% by mass. This sufficient content of reduced iron powder within this range can stably provide the required iron for aluminum alloy smelting, solving the problem of insufficient iron content and inadequate iron recovery in aluminum alloys due to excessively low iron content.

[0025] Potassium fluoroaluminate is a fluxing agent. Its melting point is lower than the melting temperature of molten aluminum, allowing potassium fluoroaluminate-based iron additives to melt rapidly at the molten aluminum temperature. Pure iron, with a melting point as high as 1538℃, far exceeds the melting temperature of molten aluminum, making it difficult for iron powder to melt directly in molten aluminum, easily leading to problems such as floating, burning, and uneven melting. Adding potassium fluoroaluminate to reduced iron powder improves wettability as a flux, enabling the reduced iron powder to alloy in molten aluminum through melting, rather than relying on physical melting, thus solving the aforementioned problems.

[0026] Potassium fluoroaluminate can be potassium tetrafluoroaluminate, which has a melting point of 546℃-580℃. Potassium fluoroaluminate-type iron additives prepared from potassium tetrafluoroaluminate readily melt in molten aluminum at 720℃-800℃, thus reducing energy consumption in aluminum alloy production.

[0027] When potassium fluoroaluminate-based iron additive is added to molten aluminum, the potassium fluoroaluminate melts rapidly and coats the surface of the reduced iron powder, allowing for uniform diffusion within the molten aluminum. The potassium fluoroaluminate-based iron additive completely melts within 3-5 minutes. Simultaneously, the potassium fluoroaluminate coating inhibits the oxidation of the reduced iron powder, preventing its loss due to oxidation when added to the molten aluminum. This reduces slag and dust generation. With the aid of potassium fluoroaluminate in dissolving and coating, the reduced iron powder integrates into the molten aluminum, improving the actual iron recovery rate.

[0028] Stearic acid is a binder. It possesses excellent binding properties, enabling it to tightly bond reduced iron powder and potassium fluoroaluminate together, thereby controlling the flowability of the reduced iron powder and potassium fluoroaluminate during the pressing process and meeting molding requirements. Stearic acid is a long-chain fatty acid. Due to the presence of polar sites such as fluoride ions, aluminum-fluorine bonds, and potassium ions on the surface of potassium fluoroaluminate, the polar ends of stearic acid molecules, i.e., the carboxyl groups, can be adsorbed onto the surface of potassium fluoroaluminate through van der Waals forces and physical adsorption. The nonpolar long-chain alkyl groups of stearic acid possess flexibility and intermolecular entanglement capabilities. The interpenetration and entanglement of these nonpolar long-chain alkyl groups can bind the reduced iron powder into a cohesive whole. Furthermore, compared to pure inorganic binders, stearic acid allows for a more uniform mixing of potassium fluoroaluminate and reduced iron powder.

[0029] Stearic acid is also a lubricant. Its excellent lubricity reduces the frictional resistance between reduced iron powder and potassium fluoroaluminate during the pressing process, allowing them to fully stack, densify, and tightly bond together under pressure. This results in a potassium fluoroaluminate-type iron agent with a density ≥3.7 g / cm³ after pressing. Consequently, this potassium fluoroaluminate-type iron agent exhibits high structural strength, making it less prone to breakage and pulverization during transportation, storage, and feeding. The high density of the potassium fluoroaluminate-type iron agent also isolates it from air and moisture, reducing oxidation and inhibiting slag formation after it is added to molten aluminum. Furthermore, its high density prevents dispersion after addition to molten aluminum, thus solving the problem of excessive slag caused by flying powder and achieving a slag-free effect.

[0030] In addition, the nonpolar long-chain alkyl groups of stearic acid extend toward the inner wall of the mold, forming a uniform and continuous lubricating film on the surface of the reduced iron powder, potassium fluoroaluminate and fatty acid blank and the inner wall of the mold. This reduces the frictional resistance between the blank and the mold, making the pressed blank surface smooth and completely demolded, thus improving the yield and production efficiency.

[0031] Thus, reduced iron powder with an iron content ≥98.5% by mass and potassium fluoroaluminate are combined through stearic acid pressing to produce a potassium fluoroaluminate-type iron agent with an iron content of 73%-77% by mass. This matches the iron requirements of aluminum alloy production, ensuring a stable and controllable iron recovery rate of ≥96%, thus solving the problem of low iron recovery rates in Al-Fe master alloys and traditional powdered iron agents. Simultaneously, the density of the potassium fluoroaluminate-type iron agent is ≥3.7 g / cm³, reducing the probability of moisture absorption and oxidation, thereby reducing iron oxidation and burn-off, resulting in slag and dust. This also solves the problems of excessive slag and dust in Al-Fe master alloys and traditional powdered iron agents.

[0032] In some embodiments, the potassium fluoroaluminate-type iron agent is formed into a regular sheet or block structure through the combined action of a pressing mold and pressing process parameters. The thickness of the potassium fluoroaluminate-type iron agent is 20mm-25mm. This allows the potassium fluoroaluminate-type iron agent to possess both sufficient structural strength and rapid, uniform melting in molten aluminum, solving the problems of excessive thickness leading to difficulty in melting and excessive thinness leading to pulverization. Furthermore, the potassium fluoroaluminate-type iron agent with a certain thickness is less prone to breakage, facilitating production, transportation, storage, and feeding.

[0033] In some embodiments, the mass fraction of stearic acid is 0.2%-0.3% based on the mass of the potassium fluoroaluminate-type iron agent. This provides sufficient binding force to bond the reduced iron powder and potassium fluoroaluminate into a molded form, without introducing excessive organic matter due to excessive addition. When the potassium fluoroaluminate-type iron agent prepared with a stearic acid mass fraction of 0.2%-0.3% is added to the molten aluminum, the stearic acid undergoes a thermal decomposition reaction, and the products of this thermal decomposition do not affect the mechanical properties of the aluminum alloy.

[0034] The second aspect of this application also provides an aluminum alloy comprising the potassium fluoroaluminate type iron agent provided in the first aspect embodiment, and thus possesses all the beneficial effects of the potassium fluoroaluminate type iron agent, which will not be repeated here.

[0035] Thirdly, such as Figure 1 As shown, this application provides a method for preparing a potassium fluoroaluminate-type iron agent. This method is used to prepare the potassium fluoroaluminate-type iron agent provided in the first aspect of this application, and includes the following steps: S100: Weigh out reduced iron powder, stearic acid and potassium fluoroaluminate according to the preset mass ratio of reduced iron powder to stearic acid and potassium fluoroaluminate. The mass of iron in the reduced iron powder accounts for 73%-77% of the total mass of the weighed stearic acid, reduced iron powder and potassium fluoroaluminate.

[0036] The mass fraction of stearic acid in the total mass of stearic acid, reduced iron powder, and potassium fluoroaluminate is 0.2%-0.3%. Based on the mass percentage of iron in the reduced iron powder and the mass percentage of stearic acid, the mass of potassium fluoroaluminate is calculated to be 21.5%-25.7% of the total mass of stearic acid, reduced iron powder, and potassium fluoroaluminate, and the corresponding mass of reduced iron powder, stearic acid, and potassium fluoroaluminate is then weighed.

[0037] Therefore, by clearly defining the mass ratio of stearic acid, reduced iron powder, and potassium fluoroaluminate, the advantages of high purity of reduced iron powder, fluxing properties of potassium fluoroaluminate, and binding and lubricating properties of stearic acid can be fully utilized. This results in a stable iron content in the prepared potassium fluoroaluminate-based iron additive, solving the problem that the potassium fluoroaluminate-based iron additive cannot meet the iron supply requirements for aluminum alloy smelting due to batching deviations. Simultaneously, it ensures uniform performance of potassium fluoroaluminate-based iron additives produced in different batches.

[0038] S200: Stearic acid, reduced iron powder and potassium fluoroaluminate are mixed and stirred to obtain a mixed powder.

[0039] Add the weighed stearic acid, reduced iron powder, and potassium fluoroaluminate to the mixing equipment. Start the mixing equipment and control the stirring parameters to ensure the three raw materials are thoroughly mixed until homogeneous, without obvious lumps or localized material accumulation, resulting in a uniformly mixed powder. This uniformly mixed powder allows pressure to be evenly transmitted to each powder particle during subsequent pressing, ensuring thorough particle packing and densification. This results in a uniform and dense cake structure with the required density, improving the cake's structural strength and reducing the probability of defects such as looseness, delamination, and cracking. Simultaneously, the thorough mixing of the three raw materials ensures that each reduced iron powder and potassium fluoroaluminate particle is evenly bonded to the stearic acid, maximizing the binding and lubricating effects of the stearic acid. In addition, by controlling the stirring parameters to achieve full mixing of the three raw materials, the problem of performance differences of potassium fluoroaluminate-type iron agent caused by human operation or insufficient mixing can be solved. This can ensure that stearic acid, reduced iron powder and potassium fluoroaluminate are evenly distributed in each batch of potassium fluoroaluminate-type iron agent produced in batches, reduce the defect rate and meet the needs of large-scale industrial production.

[0040] S300: The mixed powder is pressed under a first pressure range and a first pressing time to obtain a cake of the target weight.

[0041] The uniformly mixed powder is fed into the mold of the press, and the press is controlled to press the powder within a first pressure range and a first pressing time. After pressing, a cake of the target weight is obtained. The target weight can be set according to actual production needs, such as 495g / cake to 505g / cake. This ensures that the cakes are of uniform size, suitable for subsequent aluminum foil wrapping, storage, transportation, and aluminum alloy smelting. The fixed weight allows control over the amount of iron added to a single piece of potassium fluoroaluminate-type iron additive, making it easier for operators to accurately calculate the amount of material to be added based on the total amount of aluminum alloy to be smelted. This solves the problem of deviations in alloy composition caused by over- or under-addition of material, improving the convenience and accuracy of the smelting operation.

[0042] In some embodiments, the height of the mold cavity of the press is adjustable, and the thickness of a single disc can be 20mm-25mm via limiting bolts. Limiting the thickness of the disc during pressing ensures that pressure is evenly distributed throughout the disc, solving the problems of insufficient internal densification and porous defects caused by excessively thick discs, or insufficient structural strength and brittleness caused by excessively thin discs. Furthermore, matching the disc thickness and diameter to the mold specifications prevents issues such as burrs on the disc edges and irregular shapes during pressing, improving the quality and structural integrity of the disc forming.

[0043] In this way, the pressed cakes have uniform weight and specifications, enabling the standardization and normalization of the pressing process. This facilitates the unified debugging of the pressing machine molds and mass production, reduces production interruptions caused by specification adjustments, and improves the production efficiency of the cakes. Simultaneously, uniform specifications ensure that the volume, density, and component distribution of each potassium fluoroaluminate iron agent are consistent, improving the performance uniformity of mass-produced potassium fluoroaluminate iron agents, reducing the defect rate, and adapting to the needs of large-scale industrial production.

[0044] S400: Under a preset environment, the cake is left to stand for a first settling time to allow it to cool down to room temperature in order to obtain potassium fluoroaluminate type iron agent.

[0045] During the pressing and mixing of the powder, intense friction occurs between the powder particles, generating frictional heat that raises the temperature of the pressed cake to 50℃-65℃. Since the powder may absorb a small amount of ambient moisture during storage and mixing, and the frictional heating keeps the trace moisture inside the cake active, the pressed cake must be promptly transferred to a pre-designed environment and allowed to cool naturally to room temperature for an initial set time. During cooling, the trace moisture absorbed inside the cake gradually evaporates as the temperature decreases, thus eliminating moisture and resolving the issue of residual moisture affecting the performance of the potassium fluoroaluminate-based iron agent. After cooling is complete, the potassium fluoroaluminate-based iron agent is obtained.

[0046] Thus, the preparation method of potassium fluoroaluminate type iron agent only includes four steps: batching, mixing, pressing, and settling. The process is simple and convenient to operate, without the need for complex equipment and special processes such as high-temperature heating. This reduces the production difficulty and equipment investment of potassium fluoroaluminate type iron agent, and facilitates the large-scale continuous production of potassium fluoroaluminate type iron agent.

[0047] In some embodiments, stearic acid includes at least one of magnesium stearate, barium stearate, and sodium stearate.

[0048] Magnesium stearate, barium stearate, and sodium stearate all possess long-chain alkyl structures and polar carboxyl ends, enabling them to form stable adsorption on the polar sites on the surface of reduced iron powder and potassium fluoroaluminate particles, while simultaneously forming a lubricating film on the inner wall of the mold. In this way, magnesium stearate, barium stearate, and sodium stearate can bind reduced iron powder and potassium fluoroaluminate together, while also allowing the mixed powder to be molded, solving problems such as sticking to the mold and breakage of the green body.

[0049] The conventional melting temperature for aluminum alloys is 720℃-800℃, while the thermal decomposition temperatures of magnesium stearate, barium stearate, and sodium stearate are all between 300℃-500℃, far lower than the melting temperature of aluminum alloys. Therefore, when potassium fluoroaluminate-type iron additives are added to the aluminum alloy melt, the three stearate metal salts will rapidly undergo thermal decomposition reactions under high-temperature conditions, generating carbon dioxide, water, long-chain alkanes, and corresponding metal oxides. Among these, carbon dioxide, water, and long-chain alkanes are all volatile substances and will rapidly volatilize in the high-temperature melting environment. The metal oxides are all inorganic oxides, and their content is extremely low. They can react with trace impurities in the aluminum alloy melt or be incorporated into the melt in small amounts, without affecting the composition and mechanical properties of the aluminum alloy.

[0050] In some embodiments, stearic acid can be selected alone from magnesium stearate, barium stearate, or sodium stearate. The amount of stearic acid added, in mass ratio to reduced iron powder and potassium fluoroaluminate, still satisfies the requirement that iron in the reduced iron powder accounts for 73%-77% of the total mass of the three raw materials. Stearic acid can also be selected from at least two of magnesium stearate, barium stearate, and sodium stearate in combination. The total amount of stearic acid added after compounding remains unchanged, which can stabilize the binding and lubricating properties of stearic acid.

[0051] In some embodiments, such as Figure 2 As shown, S200: Stearic acid, reduced iron powder, and potassium fluoroaluminate are mixed and stirred, including: S2001: Add stearic acid, reduced iron powder and potassium fluoroaluminate into the mixing tank.

[0052] Add all the weighed stearic acid, reduced iron powder, and potassium fluoroaluminate into the mixing tank, ensuring that all three raw materials fall to the bottom of the tank, thus solving the problem of the three raw materials adhering to the tank wall or the mixing blades.

[0053] S2002: Control the barrel body to rotate at a speed of 5r / min-8r / min, and control the mixing blades of the mixer to rotate within the barrel at a speed of 25r / min-35r / min. The ratio of the mixing blade speed to the barrel speed is ≥4:1.

[0054] After adding stearic acid, reduced iron powder, and potassium fluoroaluminate into the mixer's drum, start the mixer and control the drum to rotate clockwise while simultaneously controlling the mixer's stirring blades to rotate counterclockwise within the drum. Continue stirring for 20-30 minutes until the mixed powder is uniform in color and free of obvious lumps. A small sample of powder can be taken for observation; if no individual stearic acid particles, reduced iron powder particles, or potassium fluoroaluminate particles are present, the mixing is complete, and the mixed powder is obtained. By controlling the rotation speed and speed ratio of the drum and stirring blades, the drum's rotation causes the mixed powder to tumble as a whole, while the high-speed rotation of the stirring blades achieves localized shearing and mixing of the powder. This synergistic effect solves the problems of stearic acid agglomeration and uneven dispersion of reduced iron powder and potassium fluoroaluminate. Simultaneously, controlling the rotation speed and speed ratio of the drum and stirring blades ensures uniform mixing while preventing powder splashing and loss due to excessive rotation speed, reducing wear on the stirring blades and drum, and extending the mixer's service life. In addition, by clearly defining the speed range and speed ratio, the mixing process is standardized, ensuring consistent quality of the mixed powders produced in batches, and consequently, ensuring uniform performance of the potassium fluoroaluminate type iron agent prepared subsequently.

[0055] In some embodiments, the ratio of the rotational speed of the stirring blades to the rotational speed of the tank is 5:1, such as the tank rotational speed being 6 r / min and the stirring blade rotational speed being 30 r / min.

[0056] In some embodiments, the first pressure range is 14MPa-18MPa; and / or the first preset duration is 2s-4s.

[0057] When preparing the mixed powder for pressing, the pressure can be slowly increased to 14MPa-18MPa to prevent cracking of the mixed powder blank caused by a sudden increase in pressure. Insufficient pressing pressure will result in a loose, weak, and easily pulverized mixed powder blank. Excessive pressure will cause the mixed powder blank to crack and stick to the mold. During pressing, the pressing time should be controlled at 14MPa-18MPa for 2-4 seconds. Too short a pressing time will result in insufficient densification of the mixed powder, while too long a pressing time will reduce production efficiency. Therefore, maintaining stable pressure during pressing allows for sufficient densification of the mixed powder, forming a well-structured cake. The combination of pressing pressure and pressing time allows the binding effect of stearic acid to be fully utilized, resulting in strong interparticle bonding and a cake density ≥3.7g / cm³, making it less prone to breakage and pulverization during transportation, storage, and feeding.

[0058] In some embodiments, the relative humidity of the preset environment is ≤40%RH; and / or the wind speed of the preset environment is 0.5m / s-1m / s; and / or the first settling time is ≤30min.

[0059] Placing the pressed cakes in a pre-defined environment with a relative humidity of ≤40%RH reduces moisture absorption, thus addressing the issues of decreased stearic acid bonding performance and oxidation of reduced iron powder. This ensures stable cake performance during storage and reduces the probability of increased slag and dust during aluminum alloy smelting using potassium fluoroaluminate-based iron additives. Placing the pressed cakes in a pre-defined environment with a wind speed of 0.5m / s-1m / s promotes rapid heat dissipation from the cake surface, resulting in uniform cooling both inside and out, reducing the probability of cracking or deformation due to excessively rapid or uneven cooling. Allowing the pressed cakes to stand for ≤30 minutes allows for cooling while simultaneously improving the production efficiency of potassium fluoroaluminate-based iron additives.

[0060] In some embodiments, such as Figure 3 As shown, after allowing the cake to stand for a first settling time to cool to room temperature to obtain potassium fluoroaluminate type iron agent, the preparation method of potassium fluoroaluminate type iron agent further includes: S500: Wrap the obtained potassium fluoroaluminate type iron agent with aluminum foil of the target thickness.

[0061] Aluminum foil possesses excellent sealing and barrier properties, effectively preventing air and moisture from contacting potassium fluoroaluminate-based iron concentrate. This reduces the probability of oxidation of reduced iron powder and moisture absorption by stearic acid, ensuring stable performance of the potassium fluoroaluminate-based iron concentrate during storage and extending its shelf life. Furthermore, the flexibility and strength of aluminum foil, when wrapped around the surface of the potassium fluoroaluminate-based iron concentrate, protect the concentrate, reducing collisions and friction during transportation and handling, and improving the yield rate of the concentrate.

[0062] Use food-grade or industrial-grade pure aluminum foil with a purity ≥99%. Control the target thickness of the aluminum foil to 20μm-30μm. Cut the foil into sheets 1.2-1.5 times larger than the surface area of ​​the cake, depending on the size of the cake. Place a single or multiple potassium fluoroaluminate iron cakes, cooled to room temperature, stably in the center of the cut aluminum foil sheets. Wrap the foil sheets around the cakes from all sides upwards, ensuring no exposed parts. Press the foil seams firmly to reduce the probability of foil detachment during transportation. Place the foil-wrapped potassium fluoroaluminate iron in a dry, ventilated storage container for later use. The shelf life of potassium fluoroaluminate iron can reach ≥12 months. Wrapping the cakes with aluminum foil reduces moisture absorption and oxidation of the potassium fluoroaluminate iron, reduces the generation of fumes and slag when added to molten aluminum, and increases the iron recovery rate to ≥96%. Meanwhile, the long-term storage of potassium fluoroaluminate-type iron facilitates the mass production, warehousing, transportation, and market circulation of potassium fluoroaluminate-type iron, reducing the production scheduling pressure and logistics costs caused by storage cycle limitations, enhancing the competitiveness of potassium fluoroaluminate-type iron in the market, and better meeting the procurement and usage needs of industrialized large-scale production and downstream aluminum alloy enterprises.

[0063] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments may be implemented in various forms and should not be construed as being limited to the embodiments set forth herein.

[0064] Example 1 To prepare 200 kg of potassium fluoroaluminate-type iron agent, weigh out 152 kg of reduced iron powder with an iron content ≥98.5%, 47.6 kg of potassium fluoroaluminate, and 0.4 kg of magnesium stearate. Mix the reduced iron powder, potassium fluoroaluminate, and magnesium stearate. Control the mixer drum to rotate clockwise at 6 r / min and the mixing blades to rotate counterclockwise at 30 r / min, stirring for 25 min to obtain a mixed powder. Press the mixed powder at 14 MPa for 2 s to obtain 500 g cakes. Place the cakes in an environment with a relative humidity ≤40%RH and a wind speed of 0.5 m / s-1 m / s, allowing them to cool naturally from 55℃ to room temperature for 10 min. Finally, wrap the potassium fluoroaluminate-type iron agent with 20 μm-30 μm double-sided passivated aluminum foil.

[0065] 35 kg of the prepared potassium fluoroaluminate iron agent was randomly selected and added into the aluminum melt at 730℃, and electromagnetically stirred for 20 min.

[0066] The stirred potassium fluoroaluminate-type iron agent is fully melted, melting rapidly with little smoke and dust and no slag, and the iron recovery rate is 97.1%.

[0067] Example 2 Based on the preparation of 90 kg of potassium fluoroaluminate type iron agent, weigh out 69 kg of reduced iron powder with an iron content ≥98.5%, 20.82 kg of potassium fluoroaluminate, and 0.18 kg of magnesium stearate. Mix the reduced iron powder, potassium fluoroaluminate, and magnesium stearate. Control the mixer barrel to rotate clockwise at 7 r / min and the mixing blades to rotate counterclockwise at 25 r / min, and stir for 25 min to obtain a mixed powder. Press the mixed powder at 16 MPa for 3 s to obtain 500 g cakes. Place the cakes in an environment with a relative humidity ≤40%RH and a wind speed of 0.5 m / s-1 m / s, allowing them to cool naturally from 58℃ to room temperature for 15 min. Finally, wrap the potassium fluoroaluminate type iron agent with 20 μm-30 μm double-sided passivated aluminum foil.

[0068] 35 kg of the prepared potassium fluoroaluminate iron agent was randomly selected and added into the aluminum melt at 735℃, and electromagnetically stirred for 20 min.

[0069] The stirred potassium fluoroaluminate-type iron agent is fully melted, melting rapidly with little smoke and dust and no slag, and the iron recovery rate is 97.5%.

[0070] Example 3 To prepare 100 kg of potassium fluoroaluminate-type iron agent, weigh out 76 kg of reduced iron powder with an iron content ≥98.5%, 47.8 kg of potassium fluoroaluminate, and 0.2 kg of magnesium stearate. Mix the reduced iron powder, potassium fluoroaluminate, and magnesium stearate. Control the mixer drum to rotate clockwise at 8 r / min and the mixing blades to rotate counterclockwise at 35 r / min, stirring for 25 min to obtain a mixed powder. Press the mixed powder at 14 MPa for 2 s to obtain 500 g cakes. Place the cakes in an environment with a relative humidity ≤40%RH and a wind speed of 0.5 m / s-1 m / s, allowing them to cool naturally from 56℃ to room temperature for 20 min. Finally, wrap the potassium fluoroaluminate-type iron agent with 20 μm-30 μm double-sided passivated aluminum foil. The potassium fluoroaluminate-type iron agent showed no oxidation or clumping after 12 months of storage.

[0071] 35 kg of the prepared potassium fluoroaluminate iron agent was randomly selected and added into the aluminum melt at 741℃, and electromagnetically stirred for 20 min.

[0072] The stirred potassium fluoroaluminate type iron agent is fully melted, melting rapidly with little smoke and dust and no slag, and the iron recovery rate is 96.8%.

[0073] Comparative Example 1 To prepare 200 kg of potassium fluoroaluminate-type iron agent, weigh out 152 kg of reduced iron powder with an iron content ≥ 98.5%, 47.8 kg of potassium fluoroaluminate, and 0.2 kg of magnesium stearate. Mix the reduced iron powder, potassium fluoroaluminate, and magnesium stearate. Control the mixer barrel to rotate clockwise at 7 r / min and the mixing blades to rotate counterclockwise at 30 r / min, stirring for 25 min to obtain a mixed powder. Press the mixed powder at 14 MPa for 2 s to obtain 500 g cakes.

[0074] The biscuit pieces did not hold their shape well, with each piece weighing more than 110g.

[0075] Comparative Example 2 Based on the preparation of 200 kg of potassium fluoroaluminate type iron agent, weigh out 152 kg of reduced iron powder with an iron content ≥98.5%, 47.7 kg of potassium fluoroaluminate, and 0.3 kg of magnesium stearate. Mix the reduced iron powder, potassium fluoroaluminate, and magnesium stearate. Control the mixer barrel to rotate clockwise at 6 r / min and the mixing blades to rotate counterclockwise at 30 r / min, and mix for 25 min to obtain a mixed powder. Press the mixed powder at 14 MPa for 3 s to obtain 500 g cakes.

[0076] The biscuit pieces did not hold their shape well, with each piece weighing more than 50g.

[0077] Comparative Example 3 35 kg of powdered iron additive produced by a certain company was added to aluminum melt at 735℃. There was obvious smoke and dust on the surface of the aluminum melt. After turning on the electromagnetic stirring for 20 minutes, the powdered iron additive did not melt completely. After turning on the electromagnetic stirring for another 5 minutes, the powdered iron additive melted completely. There was a small amount of dross on the surface of the aluminum melt. The iron recovery rate of the aluminum alloy product was 95.5%.

[0078] The potassium fluoroaluminate type iron agent formed above was subjected to the following tests, and the test results are shown in Table 1.

[0079] Actual yield test: The test was conducted according to the YS / T 492-2021 specification for the determination of actual yield.

[0080] The results of the actual yield test are shown in Table 1.

[0081] Table 1. Conditions and test results for the embodiments and comparative examples of this application.

[0082] As can be seen from Table 1 above, the potassium fluoroaluminate type iron agent prepared in Examples 1 to 3 has a higher yield than the powdered iron additive in Comparative Example 3. This indicates that the yield of the potassium fluoroaluminate type iron agent prepared in this application is improved compared with that of the traditional powdered iron agent.

[0083] Compared to Comparative Examples 1 and 2, the potassium fluoroaluminate-type iron agents prepared in Examples 1 to 3 formed well and did not exhibit any fragmentation. This indicates that the mass fraction of stearic acid in the potassium fluoroaluminate-type iron agent should not be less than 0.2%. If it is less than 0.2%, the stearic acid content is too low, making it impossible to bind the potassium fluoroaluminate and reduced iron powder into a single unit.

[0084] It should also be noted that the terms "some embodiments" or "embodiments" used in this application refer to specific features, structures, or characteristics described in connection with those embodiments, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0085] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A potassium fluoroaluminate type iron agent, characterized in that, include: Stearic acid; Reduced iron powder, wherein the mass fraction of iron in the reduced iron powder is ≥98.5%; Potassium fluoroaluminate, wherein the potassium fluoroaluminate and the reduced iron powder are pressed together by the stearic acid to form a potassium fluoroaluminate type iron agent; The potassium fluoroaluminate type iron agent has a density ≥3.7g / cm³, and the mass fraction of iron in the potassium fluoroaluminate type iron agent is 73%-77%.

2. The potassium fluoroaluminate type iron agent according to claim 1, characterized in that, The thickness of the potassium fluoroaluminate type iron agent is 20mm-25mm.

3. The potassium fluoroaluminate type iron agent according to claim 1, characterized in that, Based on the mass of the potassium fluoroaluminate type iron agent, the mass fraction of stearic acid is 0.2%-0.3%.

4. An aluminum alloy, characterized in that, include: The potassium fluoroaluminate type iron agent as described in any one of claims 1 to 2.

5. A method for preparing a potassium fluoroaluminate type iron agent, characterized in that, The method for preparing the potassium fluoroaluminate type iron agent is used to prepare the potassium fluoroaluminate type iron agent as described in any one of claims 1 to 3, and the preparation method includes: According to the preset mass ratio of reduced iron powder to stearic acid and potassium fluoroaluminate, reduce iron powder, stearic acid and potassium fluoroaluminate are weighed separately, wherein the mass of iron element in the reduced iron powder accounts for 73%-77% of the total mass of the weighed stearic acid, reduced iron powder and potassium fluoroaluminate; The stearic acid, the reduced iron powder, and the potassium fluoroaluminate are mixed and stirred to obtain a mixed powder. The mixed powder is pressed under a first pressure range and a first pressing time to obtain a cake of the target weight; Under a preset environment, the cake is left to stand for a first settling time to cool down to room temperature in order to obtain the potassium fluoroaluminate type iron agent.

6. The method for preparing potassium fluoroaluminate type iron agent according to claim 5, characterized in that, The stearic acid includes at least one of magnesium stearate, barium stearate, and sodium stearate.

7. The method for preparing potassium fluoroaluminate type iron agent according to claim 5, characterized in that, The step of mixing and stirring the stearic acid, the reduced iron powder, and the potassium fluoroaluminate includes: The stearic acid, the reduced iron powder and the potassium fluoroaluminate are added into the tank of the mixer; The barrel is controlled to rotate at a speed of 5r / min-8r / min, and the mixing blades of the mixer are controlled to rotate at a speed of 25r / min-35r / min within the barrel. The ratio of the rotational speed of the stirring blades to the rotational speed of the barrel is ≥4:

1.

8. The method for preparing potassium fluoroaluminate type iron agent according to claim 5, characterized in that, The first pressure range is 14MPa-18MPa; and / or The first suppression duration is 2s-4s.

9. The method for preparing potassium fluoroaluminate type iron agent according to claim 5, characterized in that, The relative humidity of the preset environment is ≤40%RH; and / or The preset environment has a wind speed of 0.5 m / s to 1 m / s; and / or The first settling time is ≤30min.

10. The method for preparing potassium fluoroaluminate type iron agent according to claim 5, characterized in that, The preparation method further includes: The obtained potassium fluoroaluminate type iron agent is wrapped with aluminum foil of the target thickness.

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