A method for preparing CuB alloy by magnesium-thermal self-propagating under vortex-thermoelectric coupling

Abstract

The application discloses a method for preparing CuB alloy by magnesium heat self-propagating under vortex-thermoelectric coupling and belongs to the field of copper alloy preparation. The method forms vortex in the copper melt through mechanical stirring, mixes B2O3 (boric acid) with Mg powder and introduces the mixture into the copper melt by vortex action, generates elementary substance B and MgO in-situ, and uniformly disperses the elementary substance B and MgO in the copper melt under the vortex action caused by mechanical stirring; wherein, 3MgO.B2O3 is generated by adding excessive B2O3 and newly generated MgO to form slag, the melting point of the MgO-based slag is reduced, the effect of separating the slag from the gold is improved, and H3BO4 is obtained by acid leaching of the obtained 3MgO.B2O3, low-temperature crystallization, filtration and drying. The application promotes the effective separation of the slag from the gold by the action of the thermoelectric coupling, the smelting slag after the reaction is decomposed by sulfuric acid to separate boron magnesium ore and obtain boric acid products, and the boric acid products are returned to batching, so that the clean preparation of copper boron alloy is realized.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy preparation, and specifically relates to a method for preparing CuB alloy by magnesium thermal self-propagation under eddy current-thermoelectric coupling. Background Technology

[0002] Copper-boron alloys are widely used deoxidizing materials. They can reduce the oxygen content of copper to below 20 ppm, meeting the domestic Tu1 oxygen-free copper standard. Because boron (B) has a low density, if added directly during copper smelting, it will float to the surface, failing to achieve the desired deoxidation effect. Therefore, they are generally smelted into copper-boron alloys for use. Copper-boron alloys are also an important intermediate alloy used for deoxidation in copper smelting. Furthermore, copper-boron alloys are boron-containing additives. Even trace amounts of boron (0.005%–0.05%) can significantly improve the strength and corrosion resistance of copper materials. Adding trace amounts of boron to copper alloys not only refines the microstructure and improves strength and hardness but also maintains its plasticity, significantly enhancing the corrosion resistance and wear resistance of the copper alloy. Adding copper-boron alloys to cast iron parts can improve their hardness and corrosion resistance. Important production indicators for copper-boron alloys are the mass fraction of boron in the alloy, the dispersion of boron, and the purity of the alloy.

[0003] The preparation processes for CuB alloys include the traditional aluminothermic method and the melt reduction method. The traditional aluminothermic method uses aluminum as a reducing agent to reduce boron anhydride and copper oxide outside the furnace to prepare copper-boron alloys. However, the produced copper-boron alloys are generally of low quality and have a low boron content, only 2%. Melt reduction involves adding B2O3 powder to a CuMg alloy melt, and the reduction of Mg and B2O3 achieves the preparation of CuB alloys. However, this method results in a higher magnesium impurity content and higher costs. Patent application number CN202210672236.4 uses electrolytic Cu powder and nano-B powder as raw materials, employing a combination of powder metallurgy and vacuum induction melting. First, a Cu-B pre-alloy billet is obtained through powder metallurgy. Then, combined with vacuum induction melting, the billet is melted using a pre-vacuum method with argon protection to obtain a uniform Cu-B alloy liquid. Finally, the alloy liquid is injected into a graphite mold using a bottom-pouring method through a guide tube to obtain the Cu-B alloy. Patent application CN202210671017.4 discloses a method for preparing high-strength, high-wear-resistant copper-boron alloys through hot extrusion and cold forging, comprising the following steps: Step 1: Using copper blocks and boron particles as raw materials, a copper-boron alloy ingot is prepared by directional solidification; Step 2: The copper-boron alloy ingot is machined and clad with a copper sleeve, then hot-extruded to obtain a hot-extruded copper-boron alloy material sample; Step 3: The copper-boron alloy material sample is machined to obtain a hot-extruded copper-boron alloy material, which is then cold-forged at room temperature using an air hammer to obtain a cold-forged high-strength, high-wear-resistant copper-boron alloy material. However, the above patents all use high-purity copper powder as raw material, increasing raw material costs. Therefore, how to reduce the production cost of existing production technologies while preparing copper-boron alloys with quality and performance comparable to or even better than commercial alloys to achieve good economic benefits is the research direction for CuB alloys. Summary of the Invention

[0004] This invention uses pure copper as raw material, which is rapidly melted in an induction furnace to obtain copper molten material. A vortex is formed in the copper molten material through mechanical stirring. B2O3 (boric acid) and Mg powder are mixed and introduced into the copper molten material using the vortex effect, reacting in situ to generate elemental boron (B) and MgO. Under the vortex effect induced by mechanical stirring, elemental boron is uniformly dispersed in the copper molten material. By adding excess B2O3 to react with the newly generated MgO to form 3MgO·B2O3, the melting point of the MgO-based slag is lowered, improving the slag-gold separation effect. Thermoelectric coupling further promotes effective slag-gold separation. After the reaction is complete, the smelting slag is decomposed with sulfuric acid to decompose boron-magnesium ore, and the resulting boric acid product is dehydrated and recycled, achieving the clean preparation of copper-boron alloys.

[0005] A method for preparing CuB alloys by magnesium thermal self-propagation under eddy current-thermoelectric coupling includes the following steps:

[0006] (1) According to the required copper-boron alloy, the raw material ratio is made according to the chemical equation (1) so that B2O3 is in excess, and the excess range is 1.8 to 2.5 times; after weighing Mg powder and B2O3 respectively, they are put into a mixing tank for ball milling, and then pressed into a compact to obtain a mixture.

[0007] 3Mg+2B2O3=3MgO·B2O3+2B (1);

[0008] (2) The copper block required for the reaction is melted by induction heating and stirred to generate a vortex in the melt.

[0009] (3) The mixture is added to the melt by eddy current. Under the high temperature environment of the melt and the stirring action of the eddy current, the mixture undergoes a magnesian thermal self-propagating reduction reaction, realizing the in-situ addition of B to the Cu melt, and obtaining a high temperature melt composed of homogeneous copper-boron alloy and reducing smelting slag.

[0010] (4) High-temperature melt is smelted by induction heating, forming 3MgO·B2O3 smelting slag in the upper layer and CuB alloy melt in the lower layer;

[0011] (5) Solidify the CuB alloy melt to obtain the CuB alloy ingot;

[0012] (6) The 3MgO·B2O3 smelting slag is leached with sulfuric acid to obtain a mixed solution of H3BO3 and MgSO4. The reaction equation is as shown in (2):

[0013] 3MgO·B2O3+3H2SO4=2H3BO3+3MgSO4 (2);

[0014] (7) The mixture of H3BO3 and MgSO4 is crystallized at low temperature, filtered and dried to obtain H3BO4. The mother liquor after filtration is recrystallized and the boric acid (dehydrated boric anhydride) is recycled.

[0015] Further, the induction heating temperature in step (1) is 1250-1300℃, and the heating time is 10-15min; the stirring speed is 100-200rpm, and a straight-blade open turbine propeller is used.

[0016] Further, the ball milling in step (1) involves placing the mixing tank on a high-energy ball mill and mixing for 30 to 60 minutes. After ball milling, the particle size of Mg powder and B2O3 is 25 to 50 μm.

[0017] Further, the pressure of the pressed blank in step (1) is 10-15 MPa.

[0018] Furthermore, the melting temperature in step (4) is 1500-1650℃ and the melting time is 30-60min.

[0019] Furthermore, the solidification process described in step (5) is carried out in a water-cooled crystallizer at a solidification rate of 10-20°C / s.

[0020] Furthermore, in step (6), the acid leaching time is 80-100 min, the temperature is 90-95℃, the sulfuric acid concentration is 20%-25%, and the leaching rate of B2O3 can reach more than 95%.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] (1) Compared with vacuum melting, this method uses inexpensive B2O3 as raw material, has low production cost, and does not require a high degree of vacuum when it is prepared in a non-vacuum environment.

[0023] (2) Compared with traditional metallurgical methods, this process uses the synergistic effect of reduction and mechanical stirring to make elemental B uniformly dispersed in the Cu matrix, effectively solving the segregation problem.

[0024] (3) The magnesium borate slag system generated by the present invention can be subjected to secondary treatment to achieve clean and sustainable production of CuB alloy. Attached Figure Description

[0025] Figure 1 This is a flowchart of a method for preparing CuB alloy by magnesium thermal self-propagation under eddy current-thermoelectric coupling according to the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] (1) As Figure 1 As shown, according to the composition of the CuB6 alloy ingot to be prepared, Cu blocks, B2O3 powder, and Mg powder are prepared. The B2O3 material required for the reaction is placed in an oven and dried at 150°C for 24 hours. 5 kg of Cu blocks are placed in an induction furnace and heated to 1300°C until the Cu blocks are completely melted into a molten state.

[0029] (2) The mechanical stirring system was started by a straight-blade open turbine propeller, and the stirring speed was set to 200 rpm. 3600 g of B2O3 powder and 1836 g of Mg powder were mixed and put into a mixing tank. The mixing ratio of B2O3 powder and Mg powder was 1:0.51 by weight (the amount of B2O3 added was twice the stoichiometric amount in the chemical reaction formula). The purpose was to control the amount of B added in the alloy within the range of 3% to 7% and to make the slag system biased towards 3MgO·B2O3, thereby lowering the melting point of the MgO-based slag and making the melting point of the slag around 1420℃. The mixture was mixed in a ball mill for 40 min. After mixing, the mixture was added to the melt in batches through a vortex inside the melt. A reduction reaction occurred in the high-temperature environment of the melt and under the action of vortex stirring, resulting in a CuB alloy melt with good slag-metal separation and a high-temperature melt composed of MgO3-B2O3 reduced slag.

[0030] (3) The high-temperature melt is smelted into alloy slag under the action of an electromagnetic field. The electromagnetic induction parameters are: 4000Hz, smelting temperature 1600℃, and smelting time 30min. This ensures that the slag also presents a molten state, improves the slag-gold separation effect, forms a reducing slag in the upper layer and a CuB alloy melt in the lower layer. After refining and slag removal, the copper-boron alloy ingot is solidified at 20℃ / s under the action of a water-cooled crystallizer.

[0031] (4) The B content in the copper-boron alloy is 5.6% to 5.8%, the B2O3 content in the slag is 53.6%, the MgO content is 45.8%, the acid leaching time of the slag is 100 min, the reaction temperature is 95℃, the sulfuric acid concentration is 25%, and the leaching rate of B2O3 can reach 95.2%.

[0032] Example 2

[0033] (1) Prepare Cu blocks, B2O3 powder and Mg powder according to the composition of the CuB3 alloy ingot to be prepared. Place the B2O3 material required for the reaction in an oven at 150°C for 24 hours. Put 5 kg of Cu blocks into an induction furnace and heat it to 1300°C so that the Cu blocks are completely melted into a molten state;

[0034] (2) The mechanical stirring system was activated using a six-bladed open turbine propeller, and the stirring speed was set to 150 rpm. 1391 g of B2O3 powder and 792.87 g of Mg powder were mixed and placed into a mixing tank, with the mixing ratio of B2O3 powder to Mg powder being 1:0.57 by weight (the amount of B2O3 added was 1.8 times the stoichiometric ratio of the chemical reaction). The mixture was then mixed in a ball mill for 40 min. The mixed materials were then added to the melt in batches through a vortex inside the melt. A reduction reaction occurred in the high-temperature environment of the melt and under the action of vortex stirring, resulting in a CuB alloy melt with good slag-metal separation and a high-temperature melt composed of MgO3-B2O3-based reducing slag.

[0035] (3) The high-temperature melt is smelted into alloy slag under the action of an electromagnetic field. The electromagnetic induction parameters are: 2000Hz, smelting temperature 1500℃, and smelting time 30min. A reducing slag is formed in the upper layer and a CuB alloy melt is formed in the lower layer. After refining and removing slag, the copper-boron alloy ingot is solidified at 10℃ / s under the action of a water-cooled crystallizer.

[0036] (4) The B content in the copper-boron alloy is 2.75% to 2.85%, the B2O3 content in the slag is 51.9%, the MgO content is 47.1%, the acid leaching time of the slag is 95 min, the reaction temperature is 90℃, the sulfuric acid concentration is 20%, and the leaching rate of B2O3 can reach 95.8%.

[0037] Example 3

[0038] (1) Prepare Cu blocks, B2O3 powder and Mg powder according to the composition of the CuB5 alloy ingot to be prepared. Place the B2O3 material required for the reaction in an oven at 150°C for 24 hours. Put 5 kg of Cu blocks into an induction furnace and heat it to 1300°C so that the Cu blocks are completely melted into a molten state;

[0039] (2) The mechanical stirring system was started using a six-bladed open turbine propeller, and the stirring speed was set to 180 rpm. 2703.8 g of B2O3 powder and 1243.75 g of Mg powder were mixed and placed into a mixing tank, with the mixing ratio of B2O3 powder to Mg powder being 1:0.46 by weight (the amount of B2O3 added was 2.2 times the stoichiometric amount in the chemical reaction formula). The mixture was then mixed in a ball mill for 40 min. The mixed materials were then added to the melt in batches through a vortex inside the melt.

[0040] (3) A reduction reaction occurs in the high-temperature environment of the melt and under the action of eddy current stirring to obtain a CuB alloy melt with good slag-metal separation and a high-temperature melt composed of MgO3-B2O3 reducing slag. The high-temperature melt is then smelted under the action of an electromagnetic field with the following electromagnetic induction parameters: 3500Hz, smelting temperature 1550℃, and smelting time 40min. A reducing slag is formed in the upper layer and a CuB alloy melt is formed in the lower layer. After refining and slag removal, the melt is solidified at 15℃ / s under the action of a water-cooled crystallizer to obtain a copper-boron alloy ingot.

[0041] (4) The B content in the copper-boron alloy is 4.68% to 4.80%, the B2O3 content in the slag is 54.9%, the MgO content is 44.7%, the acid leaching time of the slag is 95 min, the reaction temperature is 95℃, the sulfuric acid concentration is 25%, and the leaching rate of B2O3 can reach 96.5%.

[0042] Example 4

[0043] (1) Prepare Cu blocks, B2O3 powder and Mg powder according to the composition of the CuB7 alloy ingot to be prepared. Place the B2O3 material required for the reaction in an oven at 150°C for 24 hours. Put 5 kg of Cu blocks into an induction furnace and heat it to 1300°C so that the Cu blocks are completely melted into a molten state;

[0044] (2) The mechanical stirring system was started using a six-bladed open turbine propeller, and the stirring speed was set to 200 rpm. 4191.1 g of B2O3 powder and 1718.35 g of Mg powder were mixed in a mixing tank, with the B2O3 powder and Mg powder mixed in a weight ratio of 1:0.41 (the amount of B2O3 added was 2.5 times the stoichiometric amount in the chemical reaction formula), and mixed in a ball mill for 60 min. The mixed materials were then added to the melt in batches through a vortex inside the melt.

[0045] (3) A reduction reaction occurs in the high temperature environment of the melt and under the action of eddy current stirring to obtain a CuB alloy melt with good slag-metal separation and a high temperature melt composed of MgO3-B2O3 reducing slag. The high temperature melt is then smelted under the action of an electromagnetic field with the following electromagnetic induction parameters: 4000Hz, smelting temperature 1600℃, and smelting time 60min. A reducing slag is formed in the upper layer and a CuB alloy melt is formed in the lower layer. After refining and slag removal, the melt is solidified at 20℃ / s under the action of a water-cooled crystallizer to obtain a copper-boron alloy ingot.

[0046] (4) The B content in the copper-boron alloy is 6.85% to 6.98%, the B2O3 content in the slag is 58.7%, the MgO content is 41.3%, the acid leaching time of the slag is 100 min, the reaction temperature is 95℃, the sulfuric acid concentration is 25%, and the leaching rate of B2O3 can reach 95.1%.

[0047] Example 5

[0048] (1) Prepare Cu blocks, B2O3 powder and Mg powder according to the composition of the CuB4 alloy ingot to be prepared. Place the B2O3 material required for the reaction in an oven at 150°C for 24 hours. Put 5 kg of Cu blocks into an induction furnace and heat it to 1300°C so that the Cu blocks are completely melted into a molten state;

[0049] (2) The mechanical stirring system was activated using a six-bladed open turbine propeller, and the stirring speed was set to 100 rpm. 2007.6 g of B2O3 powder and 1023.88 g of Mg powder were mixed and placed into a mixing tank. The mixing ratio of B2O3 powder to Mg powder was 1:0.51 by weight (the amount of B2O3 added was twice the stoichiometric amount in the chemical reaction formula). The mixture was then mixed in a ball mill for 40 min. The mixed materials were then added to the melt in batches through a vortex inside the melt. A reduction reaction occurred in the high-temperature environment of the melt and under the action of vortex stirring, resulting in a CuB alloy melt with good slag-metal separation and a high-temperature melt composed of MgO3-B2O3-based reducing slag.

[0050] (3) The high-temperature melt is smelted into alloy slag under the action of an electromagnetic field. The electromagnetic induction parameters are: 2500Hz, smelting temperature 1550℃, and smelting time 30min. A reducing slag is formed in the upper layer and a CuB alloy melt is formed in the lower layer. After refining and removing slag, the copper-boron alloy ingot is solidified at 10℃ / s under the action of a water-cooled crystallizer.

[0051] (4) The B content in the copper-boron alloy is 3.59% to 3.78%, the B2O3 content in the slag is 53.5%, the MgO content is 45.6%, the acid leaching time of the slag is 90 min, the reaction temperature is 90℃, the sulfuric acid concentration is 20%, and the leaching rate of B2O3 can reach 97.2%.

Claims

1. A method for the preparation of CuB alloys by magnesiothermic self-propagating process coupled with vortex-thermoelectricity, characterized by, The method comprises the following steps: (1) according to the required copper boride alloy, the raw materials are proportioned according to chemical equation (I), B2O3 is in excess, the excess range is 1.8-2.5 times; Mg powder and B2O3 are weighed and loaded into a mixing tank, the mixing tank is placed on a high-energy ball mill for mixing for 30-60 min, and then a compact is pressed, the pressure is 10-15 Mpa, and the mixture is obtained; （I）； (2) the copper block required for the reaction is melted into a melt state through induction heating, and the melt is stirred to generate vortex flow; (3) the mixture is added to the melt in a vortex manner, the mixture is subjected to a magnesium heat self-propagating reduction reaction under the action of high-temperature melt and vortex stirring, in-situ addition of B in the Cu melt is realized, and a high-temperature melt composed of homogeneous copper boride alloy and reduction smelting slag is obtained; (4) the high-temperature melt is smelted through induction heating, 3MgO·B2O3 smelting slag is formed in the upper layer, and CuB alloy melt is formed in the lower layer; (5) the CuB alloy melt is solidified, and finally CuB alloy ingot is obtained; (6) the 3MgO·B2O3 smelting slag is acid leached with sulfuric acid to obtain a mixed solution of H3BO3 and MgSO4, and the reaction equation is as shown in (II): (I); (II); (III); (IV); (V); ( (7) the mixed solution of H3BO3 and MgSO4 is subjected to low-temperature crystallization, filtration and drying to obtain H3BO4, and the filtered mother liquor is recrystallized, and finally the boric acid is recycled.

2. The method of producing CuB alloy by magnesiothermic self-propagating process coupled with eddy current-heat according to claim 1, characterized in that, In step (2), the induction heating temperature is 1250-1300℃, the heating time is 10-15 min, the stirring speed is 100-200 rpm, and a straight-blade open-turbine paddle is used.

3. The method of producing CuB alloy by magnesiothermic self-propagating process coupled with eddy current-heat according to claim 1, characterized in that, In step (1), the ball milling is that the mixing tank is placed on a high-energy ball mill for mixing for 30-60 min, and the particle size of Mg powder and B2O3 after ball milling is 25-50 μm.

4. The method of self-propagating preparation of CuB alloy by magnesiathermitic reaction coupled with eddy-heat according to claim 1, characterized in that, In step (1), the pressure of the compact is 10-15 Mpa.

5. The method of producing CuB alloy by Mg-thermo-ignition self-propagating process coupled with eddy-current-heat according to claim 1, characterized in that, In step (4), the smelting temperature is 1500-1650℃, and the smelting time is 30-60 min.

6. The method of producing CuB alloy by Mg-thermo-ignition self-propagating process coupled with eddy-current-heat according to claim 1, characterized in that, In step (5), the solidification process is carried out in a water-cooled crystallizer at a solidification speed of 10-20℃ / s.

7. The method of self-propagating preparation of CuB alloy by magnesiathermitic reaction coupled with vortex-heat according to claim 1, characterized in that, In step (6), the acid leaching time is 80-100 min, the temperature is 90-95℃, the sulfuric acid concentration is 20%-25%, and the leaching rate of B2O3 can reach more than 95%.

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