A method and product for separating and regulating impurity elements in recycled brass

Abstract

The present application relates to a kind of separation and regulation method and product of regenerative brass impurity element, the present application does not use the chemical method of adding reagent to remove impurity, but based on the conductivity and density difference between impurity element and matrix, the content of impurity element in waste impure brass raw material is reduced using physical method;At the same time, after being treated by the method, the homogenization distribution of residual impurity element in alloy matrix is realized, which is beneficial to improve the cutting performance and mechanical properties of regenerative alloy etc.For the problem that high lead and high bismuth brass raw material is difficult to purify and utilize in the existing regenerative copper industry, the method of preparing regenerative brass alloy by electric pulse one-step separation and regulation provides a new solution for this industry.

Description

Technical Field

[0001] This invention belongs to the field of secondary non-ferrous metal recycling technology, specifically relating to a method and product for separating and controlling impurity elements in recycled brass. Background Technology

[0002] Recycled brass raw materials come from a wide variety of sources, are diverse in form, and are often contaminated by various inclusions and adhering substances. These factors result in a high variety and concentration of impurity elements in the melt during the direct smelting of recycled brass alloys, thus affecting the processing performance and physical and mechanical properties of the copper. Therefore, removing impurity elements from the melt is crucial during the smelting process of recycled brass alloys. This not only helps to fully realize the recycling potential of brass alloys but also improves the purity and overall performance of the alloy material, meeting the higher standards of industrial applications.

[0003] Based on the different characteristics of scrap copper resources, scrap copper recycling processes are divided into two main categories: direct utilization and indirect utilization. Generally, high-grade scrap copper is recycled using direct utilization methods, while low-grade scrap copper tends to be recycled indirectly. A common indirect utilization method is the two-stage process. First, crude copper is produced through pyrometallurgical smelting or blowing, followed by pyrometallurgical refining to obtain anode copper with a purity higher than 99%. This method effectively reduces impurities in scrap copper, but it has high equipment investment and operating costs, high energy consumption, and long processing times. Furthermore, this process generates sulfides, dust, and other harmful gases during refining, causing environmental pollution. Therefore, although the two-stage process is effective in improving the grade of scrap copper and removing impurities, the aforementioned drawbacks limit its application scope and efficiency. In addition, Some patented technologies also offer new solutions for the treatment of scrap copper. For example, prior art one discloses a recycled copper refining process, which includes several key steps: feeding, melting, oxidative refining, reduction refining, and finally, copper tapping. Specifically, in the oxidative refining stage, different refining agents must be used to separate various impurity elements. However, this separation process may also introduce new impurities, which is an important factor to consider in the impurity removal process. Prior art two discloses a method for removing impurities during the smelting process of copper and copper alloys. This method employs multiple steps, including a micro-oxidation stage and a micro-reduction stage, in which various oxidants and metals are used as reducing agents to harmlessly treat harmful impurity elements in scrap copper. However, this process suffers from a certain degree of loss of oxidizing and reducing media, resulting in significant burn-off of recycled metal, a decreased recovery rate, and relatively complex operation. Prior art three discloses an apparatus and method for preparing low-impurity recycled brass alloys using stepwise electrode insertion. This method requires a large current density gradient to promote the downward movement of impurity elements, but it does not fully consider the significant influence of the conductivity and density differences between impurity elements and the matrix on impurity separation. Therefore, the removal rate of impurity elements under this method is limited. Prior art four discloses a method for removing multi-element impurity elements from scrap copper using pulsed current. This method is only suitable for small-sized melts below 500g and is difficult to apply to large-volume brass melts. Furthermore, the excessively high holding temperature causes the volatilization of valuable zinc in the brass melt. Recent research progress indicates that adding trace elements can also improve the properties of copper alloys. Through specific casting techniques and the use of alloy modifiers, the microstructure and properties of copper alloys can be optimized. For example, using different casting methods and adding a B-Ti-Zr composite modifier can effectively improve the as-cast microstructure of HPb59-1, refining it and enhancing its mechanical properties. Experiments have shown that introducing 0.02 wt.% B-Ti-Zr composite modifier into leaded brass can improve its mechanical properties by more than 20%. Meanwhile, research results indicate that the microstructure of H62 brass containing 0.4 wt.% Fe shows a significant increase in hardness in the as-cast structure after the introduction of Si, but a significant decrease in electrical conductivity. Furthermore, the addition of modifiers leads to increased production costs and more complex operating procedures. Most of the above methods reduce the impurity content in recycled brass alloys or improve the ingot microstructure by adding refining agents or trace elements, but these methods present acute economic and ecological problems such as increased production costs, longer process flows, increased energy consumption, increased carbon emissions, and severe environmental pollution. Addressing the shortcomings of existing recycled brass processes, and under the premise of ensuring low loss of valuable metals in the molten metal and eliminating the need for additional reagents or trace elements, a method to reduce the impurity element content in recycled brass and homogenize the distribution of residual impurity elements has become an urgent problem to be solved. Summary of the Invention

[0004] In order to overcome the above-mentioned problems in the prior art, the present invention provides a method and product for separating and controlling impurity elements in regenerated brass, which is used to solve the above-mentioned problems in the prior art.

[0005] A method for separating and controlling impurity elements in regenerated brass involves inserting an electrode into a molten brass raw material. After the melt is cooled to a predetermined temperature and held at that temperature, a periodic pulsed current is applied to the electrode. When the electrode moves from top to bottom, impurity elements with a density greater than that of the brass matrix, which precipitate in the form of a phase, are driven to the bottom of the melt under the influence of the current density gradient. Conversely, when the electrode moves from bottom to top, impurity elements with a density less than that of the matrix, which precipitate in the form of a phase, are driven to the upper surface of the melt and removed by the smelting slag.

[0006] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein the method includes the steps of: S1. Heat and stir the scrap brass raw material to obtain a brass melt containing a high content of impurity elements; S2. Insert an electrode into the melt, and then hold the melt at a certain specified temperature. S3. Apply an electrical pulse current to the electrode, and at the same time change the direction of the electrode's movement in the melt according to the density of impurity elements in the melt, and obtain an alloy ingot after cooling; S4. Cut the ingot, grind the sample, and determine the content of impurity elements and the change in particle size in the sample.

[0007] In addition to the aspects described above and any possible implementation, an implementation is further provided in which the impurity elements include: lead (Pb) of 0.1-10 wt.%, bismuth (Bi) of 0.1-5 wt.%, iron (Fe) of 0.2-15 wt.%, and aluminum (Al) of 0.05-11 wt.%.

[0008] In addition to the aspects described above and any possible implementation, a further implementation is provided in which, when the impurity elements are lead (Pb), bismuth (Bi), iron (Fe), and aluminum (Al), the electrode is moved from top to bottom when separating impurity elements Pb and Bi with a density greater than that of the brass matrix; and the electrode is moved from bottom to top when separating impurity elements Fe and Al with a density less than that of the brass matrix.

[0009] In addition to the aspects and any possible implementations described above, an implementation is further provided, wherein S1 specifically includes: placing a container containing scrap brass raw material in a heating furnace, wherein the mass of the scrap brass raw material is 100g-5000kg, the heating temperature is 1000℃-1180℃, and the stirring time is 1min-10min.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the S2 process involves a heat preservation treatment at a certain specified temperature, specifically: the melt temperature is reduced to 800℃-850℃, and the heat preservation time is 5-60 minutes.

[0011] In addition to the aspects described above and any possible implementation, an implementation is further provided in which the mass of the small-sized melt is in the range of 100g-100kg, the electric pulse frequency is 1Hz-10kHz, the average current is 1A-250A, the peak current is 1A-500A, the voltage is 0-36V, and the electric pulse processing time is 1min-60min.

[0012] In addition to the aspects described above and any possible implementation, an implementation is further provided in which the mass of the large-size melt ranges from 100kg to 5000kg, the electric pulse frequency is from 1kHz to 20kHz, the average current is from 100A to 1000A, the peak current is from 250A to 3000A, the voltage is from 12V to 36V, and the electric pulse processing time is from 60min to 120min.

[0013] The present invention also provides a recycled brass, wherein the recycled brass is obtained by the method described above, and the Pb, Bi, Fe, and Al impurities in the recycled brass are reduced from large particles of 20μm-100μm to small particles of less than 10μm.

[0014] In addition to the aspects described above and any possible implementation, an implementation is further provided in which the impurity Pb ​​content is less than 20%, the Bi content is less than 25%, the Fe content is less than 10%, and the Al content is less than 40%.

[0015] Beneficial effects of the present invention Compared with the prior art, the present invention has the following beneficial effects: Compared with existing technologies, the method for preparing recycled brass alloys using a one-step electrical pulse separation and control method described in this invention has the following advantages: This invention does not employ chemical methods of impurity removal using reagents. Instead, it utilizes physical methods to reduce the content of impurity elements in waste brass raw materials based on the differences in electrical conductivity and density between impurity elements and the matrix. Simultaneously, this method achieves a uniform distribution of residual impurity elements in the alloy matrix, which is beneficial for improving the machinability and mechanical properties of the recycled alloy. Addressing the difficulty in purifying and utilizing high-lead and high-bismuth brass raw materials in the existing copper recycling industry, this one-step electro-pulse separation and control method for preparing recycled brass alloys provides a novel solution for this industry. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the mechanism for separating impurity elements according to the present invention; Figure 2 This is a schematic diagram of the method for separating and controlling the preparation of recycled brass alloys according to the present invention, wherein (a) is a schematic diagram of the electric pulse melt purification experiment; and (b) is a schematic diagram of the sampling location for metallographic characterization. Wherein: 1-Wire; 2-Connector; 3-Graphite electrode; 4-Crucible; 5-Brass melt; Figure 3 Statistics on the size of Pb impurity particles in the intermediate cross section with and without electrical pulse treatment: (a) control group (b) electrical pulse treatment group; Figure 4 For comparison of the metallographic images of the middle section of brass ingots with and without electrical pulse treatment, (a) metallographic image of the middle section of the ingot without electrical pulse treatment, (b) metallographic image of the middle section of the ingot after electrical pulse treatment. Figure 5 The following is a comparison of the metallographic images of the middle section of the iron brass ingot with and without electrical pulse treatment in Example 4: (a) Metallographic image of the middle section of the ingot without electrical pulse treatment, and (b) Metallographic image of the middle section of the ingot after electrical pulse treatment. Detailed Implementation

[0017] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0018] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0019] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0020] This invention provides a one-step method for separating and controlling impurity elements in regenerated brass using an electrical pulse in a low-temperature melt. This invention does not employ chemical methods of adding reagents for impurity removal; instead, it utilizes the difference in conductivity and density between the impurity elements and the matrix to reduce the content of impurity elements in waste brass raw materials through physical means. The principle is that at a relatively low melt temperature (slightly above the liquidus temperature), impurity elements precipitate in the form of a phase. Simultaneously, as the electrode moves up and down in the melt, the pulsed current provides different current densities to different parts of the melt, thus creating a current density gradient. Due to the difference in conductivity between the precipitated impurity phase and the matrix, under the action of the current density gradient, the difference in conductivity causes the "impurity phase" and the "matrix" to separate into two independent parts that coexist simultaneously. The two parts experience different forces, resulting in a "separation force" between the impurities and the matrix. To improve the internal purification effect of the melt, this invention combines the differences in conductivity and density between the impurity phase and the matrix to jointly drive the precipitated impurity phase from the middle of the melt to the top or bottom for removal. Specifically, when the electrode moves from top to bottom, impurity elements precipitated in phase form with a density greater than that of the brass matrix are driven to the bottom of the melt and accumulate under the influence of the current density gradient; while when the electrode moves from bottom to top, impurity elements precipitated in phase form with a density less than that of the matrix are driven to the upper surface and enter the smelting slag for removal. Simultaneously, the remaining low-content impurity elements are dispersed in the matrix as small particles as the melt solidifies. The principle is as follows: Figure 1 As shown, this method improves the overall cleanliness of the alloy while reducing the loss of valuable metals, and the small-sized impurity particles are dispersed in the matrix, thus enhancing the alloy's machinability and mechanical properties.

[0021] Furthermore, the method specifically includes the following steps: (S1) Heat and stir the scrap brass raw material to obtain a brass melt containing a high content of impurity elements; (S2) Insert an electrode into the melt and connect the melt to the electric pulse generator using the electrode. After the melt is cooled to a certain specified temperature, it is kept at that temperature. (S3) Adjust the parameters of the electric pulse generator. Simultaneously, based on the density of impurity elements in the melt, change the direction of electrode movement within the melt. For example, when separating impurity elements such as Pb and Bi, which have a density greater than the matrix, the electrode moves from top to bottom. At this time, the driving force provided by the current density gradient and the diffusion driving force provided by the density difference on the impurity phase both move downwards, jointly driving the impurity phase to accumulate at the bottom of the melt. When separating impurity elements such as Fe and Al, which have a density less than the matrix, the electrode moves from bottom to top. The driving force provided by the current density gradient and the diffusion driving force provided by the density difference on the impurity phase both move upwards, jointly driving the impurity phase to the top of the melt to enter the slag for removal. After cooling, an alloy ingot is obtained. (S4) The ingot is cut and the sample is polished. The content of impurity elements is determined by direct reading spectrometer and the overall removal rate is calculated. Metallographic characterization is used to quantify the change in impurity particle size.

[0022] Furthermore, the specific process of (S1) is as follows: the container containing scrap brass raw materials is placed in a heating furnace. The heating equipment includes, but is not limited to, a pit-type resistance furnace and an electromagnetic induction heating furnace. The raw material mass is 100g-5000kg, the heating temperature is 1000℃-1180℃, and the stirring time is 1min-10min. The heating temperature should not be too high, and the stirring time should be shortened as much as possible to reduce the loss of valuable metals.

[0023] Furthermore, the multi-element impurity elements in the recycled brass raw material in (S1) include one or more of the following components: Pb 0.1-10wt.%, Bi 0.1-5.0wt.%, Fe 0.2-15wt.%, and Al 0.05-11.0wt.%.

[0024] Furthermore, in step (S2), the melt is cooled to a certain specified temperature and then kept at that temperature. The specific parameters are: the melt temperature is reduced to 800℃-850℃ and the holding time is 5min-60min. This ensures that the impurity elements precipitate in the form of a phase at a lower melt temperature (slightly higher than the liquid phase temperature), so that the next step of separation can be carried out.

[0025] Furthermore, the specific parameters of (S3) are as follows: for small-sized melts, the mass range is 100g-100kg, the electric pulse frequency is 1Hz-10kHz, the average current is 1A-250A, the peak current is 1A-500A, the voltage is 0-36V, and the electric pulse processing time is 1min-60min; for large-sized melts, the mass range is 100kg-5000kg, the electric pulse frequency is 1kHz-20kHz, the average current is 100A-1000A, the peak current is 250A-3000A, the voltage is 12V-36V, and the electric pulse processing time is 60min-120min. Therefore, it can be seen that the parameters used for large and small melts are different, and the large-sized melts require a larger current parameter for separation.

[0026] Furthermore, the removal rates of various impurity elements in the entire sample of (S4) are not less than 80% for Pb, not less than 75% for Bi, not less than 90% for Fe, and not less than 60% for Al.

[0027] Furthermore, in the method of (S4), the metallographic characterization of the change in impurity particle size is as follows: after pulsed current treatment, the Pb, Bi, Fe, and Al impurities in the sample are reduced from large particles of 20μm-100μm to small particles of less than 10μm, and the particle size in the middle position is reduced by more than 50%. This is because after most of the impurity elements in the melt are removed, the remaining low-content impurity elements are affected by the driving force of the current density gradient and dispersed in the matrix as small particles as the melt solidifies.

[0028] The method has practical applications, including but not limited to smelting and continuous casting processes.

[0029] Figure 2 This is a schematic diagram of the one-step electropulse separation and control method for preparing recycled brass alloys according to the present invention. (a) is a schematic diagram of the electropulse melt purification experiment, and (b) is a schematic diagram of the metallographic characterization sampling location. In this diagram: the wire 1 is used to connect the electropulse generating device to the melt; the connector 2 connects the wire 1 to the electrode 3; the insertion position of the graphite electrode 3 is adjusted to provide different current density gradients to the melt through the electropulse, thereby promoting the separation and control of impurities; the crucible 4 is used to hold the brass metal melt, wherein the melt is brass melt 5.

[0030] The following examples illustrate this. Example 1

[0031] In this embodiment, the scrap brass raw material used is high-impurity Pb ​​brass (Pb: 4.098 wt.%), and the specific steps are as follows: (S1) 12 kg of high Pb waste brass raw material was heated to 1000℃ and stirred for 3 min to obtain brass melt containing high content of impurity elements; (S2) Add an electrode into the melt, connect the melt to the electric pulse generator using the electrode, reduce the melt temperature to 800℃, and hold for 10 minutes; (S3) The melt was connected to an electric pulse generator using a graphite electrode. The parameters of the electric pulse generator were adjusted: frequency 5000 Hz, average current 125 A, peak current 450 A, voltage 36 V, and treatment time 30 min. The electrode was slowly moved from the top to the bottom of the melt twice, each time for 15 min. After cooling, an alloy ingot was obtained. (S4) The ingot was cut and the sample was polished. The Pb impurity content was determined using a direct-reading spectrometer, and the overall removal rate was calculated. The Pb content in the middle longitudinal section decreased to 0.713 wt.% after electric pulse treatment, with a Pb removal rate of 82.6%. Metallographic characterization showed the change in Pb impurity particle size in the middle section after quantification, such as... Figure 3 As shown, after electrical pulse treatment, the average size of Pb particles in the middle part decreased from 13.139 μm to 6.179 μm, a reduction of 52.97% in particle size. Figure 4 For comparison of the metallographic images of the intermediate cross-section of brass ingots with and without electrical pulse treatment, (a) is the metallographic image of the intermediate cross-section of the ingot without electrical pulse treatment, and (b) is the metallographic image of the intermediate cross-section of the ingot after electrical pulse treatment. The comparison shows that this invention achieves the separation and control of Pb impurities in recycled brass alloys using a one-step method, with a separation rate of 82.6%, while simultaneously reducing the Pb particle size inside the ingot by 52.97%.

[0032] Example 2

[0033] In this embodiment, the scrap brass raw material uses a variety of high-impurity element brass raw materials (Pb: 0.1 wt.%, Bi: 2 wt.%, Fe: 0.5 wt.%, Al: 1.0 wt.%), and the specific steps are as follows: (S1) 50 kg of high Pb scrap brass raw material is heated to 1170℃ and stirred for 5 min to obtain brass melt containing high content of impurity elements; (S2) Add an electrode to the melt, connect the melt to the electric pulse generator using the electrode, lower the melt temperature to 810℃, and hold for 10 minutes. (S3) Connect the melt to the electric pulse generator using a graphite electrode, adjust the parameters of the electric pulse generator, the electric pulse frequency is 10kHz, the average current is 500A, the peak current is 1000A, the voltage is 36V, the electric pulse processing time is 60 min, and at the same time the electrode moves up and down repeatedly in the melt in a regular manner. The process of the electrode moving back and forth from the top to the bottom is defined as one movement, and a total of 4 movements are made, each lasting 15 min. After cooling, an alloy ingot is obtained. (S4) The ingot was cut and the sample was polished. The content of multi-component impurities was determined using a direct-reading spectrometer, and the overall removal rate was calculated. After electro-pulse treatment, the Pb content in the middle longitudinal section decreased to 0.014 wt.%, with a Pb removal rate of 86.0%; the Bi content decreased to 0.48 wt.%, with a Bi removal rate of 76%; the Fe content decreased to 0.183 wt.%, with an Fe removal rate of 63.40%; and the Al content decreased to 0.5 wt.%, with a Pb removal rate of 50.0%. After electro-pulse treatment, the average size of Pb particles in the middle part decreased from 10.2 μm to 4.179 μm, a reduction of 59.03%. At the same time, the particle sizes of Bi, Fe, and Al decreased by 60.13%, 65.75%, and 52%, respectively. By comparison, the one-step method of this invention achieves the separation and particle size control of multi-component impurities in recycled brass alloy raw materials.

[0034] Example 3

[0035] In this embodiment, the scrap brass raw material used is high-impurity Bi brass raw material (Bi: 10.453 wt.%), and the specific steps are as follows: (S1) Heat 100g of high-Bi waste brass raw material to 1050℃, stir and keep warm for 1min to obtain brass melt containing high content of impurity elements; (S2) Add an electrode into the melt, and use the electrode to connect the melt to the electric pulse generator to reduce the temperature of the melt to 812°C and hold for 1 minute. (S3) Connect the melt to the electric pulse generator using a graphite electrode, keep it warm for 1 min, adjust the parameters of the electric pulse generator: electric pulse frequency is 100 Hz, average current is 1 A, peak current is 100 A, voltage is 12 V, electric pulse processing time is 5 min, and the electrode is slowly moved from top to bottom once. After cooling, an alloy ingot is obtained. (S4) The ingot was cut and the sample was polished. The content of Bi impurity elements was determined by direct-reading spectrometer and the overall removal rate was calculated. The Bi content in the middle longitudinal section after electro-pulse treatment was reduced to 2.091 wt.%, and the Bi removal rate was 80.0%. After electro-pulse treatment, the average size of Bi particles in the middle part decreased from 19.86 μm to 8.954 μm, and the particle size was reduced by 54.92%. By comparison, the one-step method of this invention has achieved the separation and particle size control of high Bi impurity elements in recycled brass alloy raw materials.

[0036] Example 4

[0037] In this embodiment, the waste brass raw material used is high-impurity Fe brass raw material (Fe: 15 wt.%), and the specific steps are as follows: (S1) 1000 kg of high-Fe waste brass raw material is heated to 1180℃ and stirred for 10 min to obtain brass melt containing high content of impurity elements; (S2) Add an electrode to the melt and connect the melt to the electric pulse generator using the electrode to reduce the temperature of the melt to 69% of the heating temperature, i.e. 810℃, and hold for 60 minutes. (S3) Connect the melt to the electric pulse generator using a graphite electrode, keep it at a temperature for 1 min, adjust the parameters of the electric pulse generator: electric pulse frequency of 15 kHz, average current of 800 A, peak current of 1000 A, voltage of 36 V, electric pulse processing time of 115 min, and at the same time, the electrode moves up and down repeatedly in the melt in a regular manner. The distance the electrode moves from bottom to top is defined as one movement process. A total of 3 movements are made, each lasting 38 min. (S4) Melt sampling and analysis before and after electro-pulse treatment: Fe impurity element content was determined using a direct-reading spectrometer, and the overall removal rate was calculated. The Fe content in the middle longitudinal section decreased to 0.75 wt.% after electro-pulse treatment, with an Fe removal rate of 95%. After electro-pulse treatment, the average size of Bi particles in the middle section decreased from 61.98 μm to 1.36 μm, a reduction of 97.81%. See the detailed electron microscopy comparison images below. Figure 5As shown, (a) is a metallographic image of Fe particles in the middle section of the ingot without electrical pulse treatment, and (b) is a metallographic image of Fe particles in the middle section of the ingot after electrical pulse treatment. By comparison, the one-step method of this invention achieves the separation of impurity elements and particle size control in large-size high-Fe brass raw material melt.

[0038] Example 5

[0039] In this embodiment, the scrap brass raw material used is high-impurity Pb, Bi, and Fe brass raw material (Pb: 5.03 wt.%, Bi: 8.12 wt.%, Fe: 6.3 wt.%). The specific steps are as follows: (S1) Heat 4500 kg of raw material to 1160 °C and stir for 10 min to obtain brass melt containing high content of impurity elements; (S2) Add an electrode into the melt, and use the electrode to connect the melt to the electric pulse generator to reduce the temperature of the melt to 850°C and hold for 60 minutes. (S3) Connect the melt to the electric pulse generator using a graphite electrode, keep it at a temperature for 15 minutes, adjust the parameters of the electric pulse generator: electric pulse frequency of 20kHz, average current of 1000A, peak current of 2500A, voltage of 36V, electric pulse processing time of 120 minutes, and at the same time, the electrode moves up and down repeatedly in the melt in a regular manner. The distance the electrode moves back and forth from the top to the bottom is defined as one movement process. A total of 4 movements are made, each lasting 30 minutes. (S4) Melt sampling and analysis before and after electro-pulse treatment were conducted. The contents of Pb, Bi, and Fe impurities were determined using a direct-reading spectrometer, and the overall removal rate was calculated. The contents of Pb, Bi, and Fe in the middle longitudinal section after electro-pulse treatment decreased to 0.211 wt.%, 0.458 wt.%, and 0.380 wt.%, respectively, with removal rates of 95.81%, 94.36%, and 93.97%. After electro-pulse treatment, the particle size of Pb, Bi, and Fe particles in the middle section decreased by 96%, 95%, and 91%, respectively. By comparison, the one-step method of this invention achieves the separation and particle size control of multiple impurities in large-size high-Pb, high-Bi, and high-Fe brass raw material melts.

[0040] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for separating and controlling impurity elements in regenerated brass, characterized in that, This method involves inserting an electrode into molten brass, holding the melt at 800-850°C, and then applying a periodic pulsed current to the electrode while moving it from top to bottom and / or bottom to top. When the electrode moves from top to bottom, impurity elements with a density greater than that of the brass matrix, which precipitate in the form of a phase, are driven to the bottom of the melt under the influence of the current density gradient. When the electrode moves from bottom to top, impurity elements with a density less than that of the brass matrix, which precipitate in the form of a phase, are driven to the upper surface of the melt and removed by the smelting slag.

2. The method for separating and controlling impurity elements in regenerated brass according to claim 1, characterized in that, The method includes the following steps: S1. Heat and stir the scrap brass raw material to obtain a brass melt containing a high content of impurity elements; S2. Insert an electrode into the molten brass and then heat-treat the molten brass to 800℃-850℃. S3. Apply an electrical pulse current to the electrode, and at the same time change the direction of movement of the electrode in the brass melt according to the density of impurity elements in the brass melt, and obtain an alloy ingot after cooling; S4. Cut the ingot, grind the sample, and determine the content of impurity elements and the change in particle size in the sample.

3. The method for separating and controlling impurity elements in regenerated brass according to claim 2, characterized in that, The impurity elements include: lead (Pb) of 0.1-10 wt.%, bismuth (Bi) of 0.1-5 wt.%, iron (Fe) of 0.2-15 wt.%, and aluminum (Al) of 0.05-11 wt.%.

4. The method for separating and controlling impurity elements in regenerated brass according to claim 3, characterized in that, When the impurity elements are lead (Pb), bismuth (Bi), iron (Fe), and aluminum (Al), the electrode is moved from top to bottom when separating impurity elements Pb and Bi with a density greater than that of the brass matrix; and from bottom to top when separating impurity elements Fe and Al with a density less than that of the brass matrix.

5. The method for separating and controlling impurity elements in regenerated brass according to claim 2, characterized in that, S1 specifically includes: placing a container containing scrap brass raw material in a heating furnace, wherein the mass of the scrap brass raw material is 100g-5000kg, the heating temperature is 1000℃-1180℃, and the stirring time is 1min-10min.

6. The method for separating and controlling impurity elements in regenerated brass according to claim 2, characterized in that, The heat preservation time in S2 is 5-60 minutes.

7. The method for separating and controlling impurity elements in regenerated brass according to claim 2, characterized in that, The melt mass range is 100g-100kg, the electric pulse frequency is 1Hz-10kHz, the average current is 1A-250A, the peak current is 1A-500A, the voltage is 0-36V, and the electric pulse treatment time is 1min-60min.

8. The method for separating and controlling impurity elements in regenerated brass according to claim 2, characterized in that, The melt mass range is 100kg-5000kg, the electric pulse frequency is 1kHz-20kHz, the average current is 100A-1000A, the peak current is 250A-3000A, the voltage is 12V-36V, and the electric pulse treatment time is 60min-120min.

9. A type of recycled brass, characterized in that, The recycled brass is obtained by the method described in any one of claims 1-8, wherein the Pb, Bi, Fe, and Al impurities in the recycled brass are reduced from large particles of 20μm-100μm to small particles of less than 10μm.

10. The recycled brass according to claim 9, characterized in that, The impurities present are: Pb content less than 20%, Bi content less than 25%, Fe content less than 10%, and Al content less than 40%.

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