A method for preparing metallic beryllium based on the silicon thermal reduction of beryllium oxide in a vacuum according to the pidgeon method and metallic beryllium

Abstract

The present application relates to the technical field of metal beryllium preparation, in particular to a method for preparing metal beryllium based on the vacuum silicon thermal reduction of the Piyin method and metal beryllium, comprising the following steps: step 1, raw material pretreatment; step 2, batching and mixing; step 3, preparation of material balls; step 4, loading and vacuumizing; step 5, primary reduction: using gradient heating to heat the crucible, and vacuum high-temperature reduction of the sintered material balls; then using a sectional condensing device to condense the beryllium vapor obtained by high-temperature reduction to obtain primary crude beryllium; step 6, secondary reduction: mixing the primary crude beryllium with industrial silicon powder and then loading into a graphite crucible, and keeping the temperature at 1380-1450 DEG C under a vacuum degree of less than or equal to 1 Pa for 2-3 h to obtain secondary crude beryllium; step 7, refining and purification. Through the process of raw material ultra-pure pretreatment, high-proportion reducing agent batching, high-pressure ball preparation sintering, gradient heating high-vacuum reduction, sectional condensing, secondary reduction and vacuum remelting purification, the metal beryllium reduction rate is successfully increased to more than 90%.

Description

Technical Field

[0001] This invention relates to the field of beryllium preparation technology, specifically to a method for preparing beryllium based on Pidgeon method vacuum silicon thermal reduction and beryllium. Background Technology

[0002] Metallic beryllium (Be) plays an indispensable strategic role in defense and high-tech fields such as aerospace, nuclear industry, weapon systems, X-ray windows, and high-end electronics due to its unique physicochemical properties, including low density, high melting point, high elastic modulus, excellent thermal conductivity, and X-ray permeability. With the increasing demand for high-performance materials in modern industry, developing efficient, low-cost, and high-purity metallic beryllium preparation technologies has become an important issue in the industry.

[0003] Currently, the mainstream industrial method for preparing metallic beryllium is the metallothermic reduction method, mainly including the magnesium thermal reduction method using beryllium fluoride (BeF2) as a raw material and the reduction method using beryllium oxide (BeO) as a raw material. While the magnesium thermal reduction method is relatively mature, it suffers from problems such as the highly toxic and hygroscopic nature of the raw material BeF2, the highly corrosive nature of the preparation process, and the difficulty in controlling the exothermic reaction. For example, Chinese patent CN113186397A discloses a method for preparing metallic beryllium beads, which aims to suppress the volatilization loss of magnesium and beryllium fluoride and improve the beryllium yield by reacting under a specific positive pressure argon atmosphere. However, this reflects the challenge of low product yield in existing thermal reduction processes. Therefore, researching reduction routes using beryllium oxide, which has more stable chemical properties and relatively lower toxicity, as a raw material is of great significance.

[0004] Applying the mature vacuum silicothermic reduction process (i.e., the Pidgeon process) to beryllium oxide reduction is a potential technological approach. The Pidgeon process has been industrially applied on a large scale in the production of metallic magnesium, and its process principle shares similarities with the vacuum reduction of BeO. However, because BeO's stability is much higher than that of magnesium oxide (MgO), directly applying the process parameters of the Pidgeon process for magnesium smelting, such as vacuum degree, reduction temperature, and feed system, is far from meeting the requirements for efficient BeO reduction, resulting in incomplete reduction reactions and extremely low beryllium reduction rates (typically below 60%). Chinese patent CN113088752A also mentions in its background section that "vacuum silicothermic reduction using silicon as a reducing agent in a vacuum" is one method for producing low-boiling-point metals, but it itself uses a carbothermic reduction method to prepare beryllium copper alloys and does not provide a vacuum silicothermic reduction scheme suitable for preparing pure metallic beryllium.

[0005] In summary, existing beryllium metal preparation technologies, especially the reduction process for beryllium oxide, generally suffer from the following pressing technical problems that need to be addressed: 1. Low reduction rate: Due to the extremely high chemical stability of beryllium oxide, the reaction kinetics of existing thermal reduction processes (whether carbothermic or silicon-thermal) are insufficient, resulting in incomplete reduction reactions. The single-pass reduction rate of metallic beryllium is generally low, causing huge waste of raw materials and high production costs.

[0006] 2. Insufficient product purity: During the high-temperature reduction process, reducing agents (such as Si), other impurities in the furnace charge, and reaction byproducts are easily volatilized along with beryllium vapor or contaminate the product in the form of slag. The lack of effective online separation and deep purification methods results in low purity of crude beryllium, which is difficult to meet the needs of high-end applications.

[0007] 3. Complex process and poor controllability: In order to pursue a higher reduction rate, existing processes often require extremely stringent equipment conditions and process parameters, resulting in a complex system, high energy consumption, poor operational controllability, and failure to systematically solve the safety operation problems caused by the high toxicity of beryllium, which is not conducive to pilot-scale amplification and industrial production. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides a method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction, and metallic beryllium.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction includes the following steps: Step 1, Raw material pretreatment: Vacuum dry beryllium oxide, industrial silicon powder and calcium fluoride separately, cool and place them in a desiccator for later use; Step 2, Ingredient Mixing: Mix and grind the dried beryllium oxide, industrial silicon powder and calcium fluoride in a molar ratio of 2:(1.8-2.2):(0.6-0.8) and then sieve. Step 3, Pellet Preparation: The sieved mixture is pressed into pellets with a particle size of 3-8 mm. Under vacuum conditions, the pellets are first dried at 150-200℃ for 3-5 hours, and then sintered at 600-650℃ for 1-2 hours to obtain a density ≥2.0 g / cm³. 3 sintered pellets; Step 4, Loading and Vacuuming: Load the sintered pellets into the graphite crucible of the vacuum distillation furnace. After sealing the furnace, first evacuate the vacuum inside the furnace to ≤50Pa, and then evacuate it to ≤1Pa. Step 5, Primary Reduction: A gradient heating crucible is used to perform vacuum high-temperature reduction on the sintered pellets; then a segmented condenser is used to condense the beryllium vapor obtained from the high-temperature reduction to obtain primary crude beryllium. Step 6, Secondary Reduction: After mixing the primary crude beryllium with industrial silicon powder, it is placed back into a graphite crucible and kept at 1380-1450℃ and vacuum degree ≤1Pa for 2-3 hours to obtain secondary crude beryllium; Step 7, Refining and Purification: After acid washing, vacuum remelting, and cooling under inert gas protection, the secondary crude beryllium is obtained as metallic beryllium.

[0010] Further, in step 1, beryllium oxide is vacuum dried at 150-160℃ for 3-4 hours, and industrial silicon powder and calcium fluoride are vacuum dried at 120-130℃ for 2-3 hours respectively; the moisture content of the dried beryllium oxide, industrial silicon powder and calcium fluoride is ≤0.05%; the purity of beryllium oxide is ≥99.5%, the purity of industrial silicon powder is ≥99%, the purity of calcium fluoride is ≥98%, and the particle size of beryllium oxide, industrial silicon powder and calcium fluoride is ≤300 mesh.

[0011] Furthermore, in step 2, the beryllium oxide, industrial silicon powder, and calcium fluoride are mixed, ground, and then passed through a 180-200 mesh sieve.

[0012] Furthermore, in step 3, the pressure of pressing the spheres is 8-12 MPa, and the porosity of the spheres is ≤5%.

[0013] Furthermore, in step 4, a two-stage vacuum system is used for evacuation, which includes a rotary vane vacuum pump and a diffusion pump.

[0014] Further, in step 5, the specific parameters for the gradient heating and heat preservation are as follows: heating at 3-5℃ / min to 700-800℃ and holding for 1-2 hours; heating at 2-3℃ / min to 1100-1200℃ and holding for 2-3 hours; heating at 1-2℃ / min to 1380-1450℃ and holding for 6-8 hours; the segmented condensation device includes a primary condensation zone and a secondary condensation zone, the temperature of the primary condensation zone is 450-550℃, and the temperature of the secondary condensation zone is 200-300℃.

[0015] Furthermore, in step 6, the amount of industrial silicon powder added is 5-10% of the mass of the primary crude beryllium, the purity of the primary crude beryllium is ≥95%, and the purity of the secondary crude beryllium is ≥98%.

[0016] Further, in step 7, the pickling is performed using a mixture of 5-7% hydrochloric acid and 0.5-1% hydrofluoric acid, and ultrasonically for 40-60 minutes at 50-60℃; the vacuum remelting temperature is 1400-1450℃, the vacuum degree is ≤0.5Pa, and the remelting time is 1-2 hours; the inert gas is high-purity argon with a purity ≥99.999%.

[0017] This invention also includes the following technical solutions: A metallic beryllium prepared using the above method.

[0018] Furthermore, the purity of the beryllium metal is ≥99%, and the impurities include Si≤0.5%, Ca≤0.3%, and Fe≤0.1%.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing metallic beryllium based on the Pidgeon process using vacuum silicothermic reduction, and the resulting metallic beryllium. Using high-purity beryllium oxide, industrial silicon powder, and calcium fluoride as raw materials, and relying on a two-stage vacuum distillation furnace, the integrated process of ultrapure raw material pretreatment, high-proportion reducing agent formulation, high-pressure ball sintering, gradient-heating high-vacuum reduction, segmented condensation, secondary reduction, and vacuum remelting purification effectively enhances the reaction kinetics of beryllium oxide reduction, successfully increasing the metallic beryllium reduction rate to over 90%, significantly improving raw material utilization and production efficiency. Simultaneously, through ultrapure raw material control and segmented condensation, efficient separation of beryllium from impurities is achieved. Combined with multiple purification processes including acid washing and vacuum remelting, high-purity metallic beryllium preparation is realized. The finished product meets purity standards and impurity content is precisely controlled, fully satisfying the quality requirements of various fields for metallic beryllium. Attached Figure Description

[0020] Figure 1 A process flow diagram of the present invention is shown. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Reference Appendix Figure 1 A method for preparing metallic beryllium using vacuum silicothermic reduction based on the Pidgeon process is disclosed. This method uses high-purity beryllium oxide as the beryllium source, industrial silicon powder as the reducing agent, and calcium fluoride as the fluxing mineralizer. Through steps including ultrapure raw material pretreatment, high-proportion reducing agent batching, high-pressure ball sintering, gradient temperature high-vacuum reduction, segmented condensation, secondary reduction, and vacuum remelting purification, the method achieves efficient preparation of metallic beryllium with a reduction rate ≥90%. The specific steps include: Step 1, Ultrapure Pretreatment of Raw Materials: Vacuum dry beryllium oxide, industrial silicon powder and calcium fluoride separately, cool and place them in a desiccator for later use; Step 2, High-proportion ingredient mixing and ultra-uniform mixing: Dry beryllium oxide, industrial silicon powder and calcium fluoride are mixed and ground in a molar ratio of 2:(1.8-2.2):(0.6-0.8) and then sieved; Step 3: High-Pressure Ball Forming and Low-Temperature Sintering: The sieved mixture is pressed into balls with a particle size of 3-8 mm. Under vacuum conditions, the balls are first dried at 150-200℃ for 3-5 hours, and then sintered at 600-650℃ for 1-2 hours to obtain a density ≥2.0 g / cm³. 3 sintered pellets; Step 4, Double-stage vacuum loading and leak detection: Load the sintered material balls into the graphite crucible of the vacuum distillation furnace, seal the furnace body, first evacuate the vacuum inside the furnace to ≤50Pa, hold the pressure and check for leaks, then evacuate to ≤1Pa. Step 5, Gradient heating high vacuum reduction and segmented condensation: A gradient heating crucible is used to perform vacuum high-temperature reduction on the sintered pellets; then a segmented condensation device is used to condense the beryllium vapor obtained from the high-temperature reduction to obtain primary crude beryllium; Step 6, primary crude beryllium collection and secondary reduction: The primary crude beryllium is mixed with industrial silicon powder and then placed back into a graphite crucible. It is kept at 1380-1450℃ and vacuum degree ≤1Pa for 2-3 hours to obtain secondary crude beryllium. Step 7, Refining and Purification and Finished Product Preparation: After acid washing, vacuum remelting and inert gas protection cooling, the secondary crude beryllium is obtained as metallic beryllium.

[0023] In step 1, beryllium oxide with a purity ≥99.5% and a particle size ≤300 mesh is vacuum dried at 150-160℃ for 3-4 hours; industrial silicon powder with a purity ≥99% and a particle size ≤300 mesh, and calcium fluoride with a purity ≥98% and a particle size ≤300 mesh are vacuum dried at 120-130℃ for 2-3 hours respectively; the moisture content of the dried beryllium oxide, industrial silicon powder, and calcium fluoride is ≤0.05%. After drying, they are quickly placed in a desiccator to cool to room temperature to prevent moisture absorption and secondary contamination.

[0024] In step 2, the mixing and grinding are carried out using a planetary ball mill with graphite grinding balls at a ball-to-material ratio of (4-5):1. The mixture is dry-ground for 2-3 hours until the material is completely uniform in color, and then passed through a 180-200 mesh sieve to ensure that there are no particles clumping.

[0025] In step 3, the pressure of pressing the pellets is 8-12 MPa, the weight of a single pellet is 0.5-1 g, and the porosity of the pellets is ≤5%. During the vacuum drying and sintering process, a vacuum environment is maintained throughout to ensure that the pellets are not subject to secondary contamination. After sintering, a dense sintered body is formed, which avoids the pellets from pulverizing during furnace heating and improves the permeability and reaction efficiency of the furnace charge.

[0026] In step 4, the graphite crucible is a high-purity graphite crucible with a purity ≥99.9%. The filling height of the sintered material balls is 2 / 3 of the crucible volume, with sufficient beryllium vapor flow channels reserved. A graphite cover plate with micropores is placed at the crucible mouth. A two-stage vacuum system is used for evacuation, which includes a rotary vane vacuum pump and a diffusion pump. After evacuating to ≤50Pa, the pressure is held for 10 minutes for preliminary leak detection. After evacuating to ≤1Pa, the pressure is held for 30 minutes to confirm that there is no vacuum leakage. The vacuum level decrease is ≤0.05Pa / h.

[0027] In step 5, the specific parameters for gradient heating and holding are as follows: In the preheating section, the temperature is increased to 700-800℃ at a rate of 3-5℃ / min and held for 1-2 hours to further remove trace impurities from the pellets, soften the pellets initially, and improve the reaction activity; In the medium-temperature slag melting section, the temperature is increased to 1100-1200℃ at a rate of 2-3℃ / min and held for 2-3 hours, where calcium fluoride forms a low-melting-point slag with beryllium oxide and silicon dioxide, with a melting point ≤1050℃, which completely destroys the dense crystal form of beryllium oxide; In the high-temperature deep reduction section, the temperature is increased to 1380-1450℃ at a rate of 1-2℃ / min and held for 6-8 hours, where the main reduction reaction is 2BeO + Si = 2Be(g) + SiO2; The vacuum degree inside the furnace is maintained at ≤1Pa throughout the process.

[0028] In step 5, the segmented condensation device is a segmented oxygen-free copper condensation device, including a primary condensation zone and a secondary condensation zone. The temperature of the primary condensation zone is 450-550℃, where beryllium vapor is condensed into high-purity flake-shaped metallic beryllium. The temperature of the secondary condensation zone is 200-300℃, where impurity vapors such as silicon, calcium, and beryllium fluoride are condensed, achieving effective separation from beryllium. After the reduction reaction is completed, heating is stopped, and the vacuum degree inside the furnace is maintained at ≤1Pa. The temperature is slowly reduced to below 200℃ at a rate of 3-5℃ / min. High-purity argon gas is introduced to break the vacuum until it reaches equilibrium with atmospheric pressure. The primary crude beryllium from the primary condensation zone is collected. The purity of the primary crude beryllium is ≥95%, and the particle size is ground to ≤2mm.

[0029] In step 6, the amount of industrial silicon powder added is 5-10% of the mass of the primary crude beryllium, and the purity of the secondary crude beryllium obtained after secondary reduction is ≥98%.

[0030] In step 7, the pickling uses a mixture of 5-7% hydrochloric acid and 0.5-1% hydrofluoric acid, with the liquid level covering the secondary crude beryllium. The mixture is ultrasonicated at 50-60℃ for 40-60 minutes. After pickling, the mixture is repeatedly washed with deionized water until the pH of the washing solution is 7. The vacuum remelting temperature is 1400-1450℃, the vacuum degree is ≤0.5Pa, and the remelting time is 1-2 hours. The inert gas is high-purity argon with a purity ≥99.999%. After remelting, the temperature is lowered to 800℃ at a rate of 2℃ / min, and then naturally cooled to room temperature under the protection of inert gas.

[0031] Example 1 Step 1: Raw material pretreatment: 99.5% purity beryllium oxide with a particle size of 300 mesh was vacuum dried at 150℃ for 4 hours; 99% purity industrial silicon powder with a particle size of 300 mesh and 98% purity calcium fluoride with a particle size of 300 mesh were vacuum dried at 120℃ for 2 hours respectively. After cooling, all three raw materials were placed in a desiccator for later use. The moisture content of the dried beryllium oxide was found to be 0.04%, the industrial silicon powder 0.05%, and the calcium fluoride 0.02%.

[0032] Step 2, Ingredient Mixing: Weigh the pretreated raw materials according to the molar ratio of beryllium oxide: industrial silicon powder: calcium fluoride = 2:1.8:0.6, put them into a grinding equipment and mix and grind them until uniform. Then pass them through a 180-mesh sieve to remove coarse particles that are not uniformly ground.

[0033] Step 3: Pellet Preparation: The sieved mixture was pressed into pellets with a particle size of 3 mm using a pressure of 8 MPa. The pellets were then placed in a vacuum environment and dried at 150°C for 5 hours, followed by sintering at 600°C for 2 hours. After cooling, a pellet with a density of 2.0 g / cm³ was obtained. 3 5% porosity sintered pellets.

[0034] Step 4: Loading and Vacuuming: Evenly load the sintered pellets into the graphite crucible of the vacuum distillation furnace and seal the furnace body. Use a two-stage vacuum system consisting of a rotary vane vacuum pump and a diffusion pump to evacuate the furnace. First, evacuate the furnace to a vacuum level of 50 Pa, then continue evacuating to 1 Pa, and maintain the vacuum state for later use.

[0035] Step 5, Primary Reduction: The graphite crucible is heated using a gradient heating and holding process: the temperature is increased to 700℃ at a rate of 3℃ / min and held for 2 hours; then increased to 1100℃ at a rate of 2℃ / min and held for 3 hours; finally, the temperature is increased to 1380℃ at a rate of 1℃ / min and held for 8 hours to complete the vacuum high-temperature reduction. A segmented condenser is used to condense the beryllium vapor generated during reduction. The temperature of the first-stage condenser is 450℃, and the temperature of the second-stage condenser is 200℃. Primary crude beryllium with a purity of 95% is collected.

[0036] Step 6, Secondary Reduction: Weigh out 5% of the mass of the primary crude beryllium, mix it thoroughly with the primary crude beryllium, and then put it back into a graphite crucible. Keep it at 1380℃ and 1 Pa vacuum for 3 hours. After cooling, you will get secondary crude beryllium with a purity of 98%.

[0037] Step 7, Refining and Purification: Prepare a mixed pickling solution with a mass fraction of 5% hydrochloric acid and 0.5% hydrofluoric acid. Place the secondary crude beryllium into the mixed solution and sonicate at 50°C for 60 minutes to remove surface impurities. Place the pickled crude beryllium in a vacuum furnace and vacuum remelt at 1400°C and a vacuum degree of 0.5 Pa for 2 hours. After remelting, purify it with 99.999% high-purity argon gas for protective cooling to obtain the finished metallic beryllium.

[0038] The finished beryllium metal was tested and found to have a purity of 99.1%, a beryllium reduction rate of 91.2%, and impurity contents of 0.45% Si, 0.28% Ca, and 0.09% Fe.

[0039] Example 2 Step 1: Raw material pretreatment: 99.5% purity beryllium oxide with a particle size of 300 mesh was vacuum dried at 160℃ for 3 hours; 99% purity industrial silicon powder with a particle size of 300 mesh and 98% purity calcium fluoride with a particle size of 300 mesh were vacuum dried at 130℃ for 3 hours respectively. After cooling, all three raw materials were placed in a desiccator for later use. The moisture content of the dried beryllium oxide was found to be 0.03%, the industrial silicon powder 0.05%, and the calcium fluoride 0.05%.

[0040] Step 2, Ingredient Mixing: Weigh the pretreated raw materials according to the molar ratio of beryllium oxide: industrial silicon powder: calcium fluoride = 2:2.2:0.8, put them into a grinding equipment and mix and grind them until uniform. Then pass them through a 200-mesh sieve to remove coarse particles that are not uniformly ground.

[0041] Step 3: Pellet Preparation: The sieved mixture was pressed into pellets with a particle size of 8 mm using a pressure of 12 MPa. The pellets were then placed in a vacuum environment and dried at 200℃ for 3 hours, followed by sintering at 650℃ for 1 hour. After cooling, a pellet with a density of 2.1 g / cm³ was obtained. 3 Sintered pellets with a porosity of 4%.

[0042] Step 4: Loading and Vacuuming: Evenly load the sintered pellets into the graphite crucible of the vacuum distillation furnace and seal the furnace body. Use a two-stage vacuum system consisting of a rotary vane vacuum pump and a diffusion pump to evacuate the furnace. First, evacuate the furnace to a vacuum level of 50 Pa, then continue evacuating to 1 Pa, and maintain the vacuum state for later use.

[0043] Step 5, Primary Reduction: The graphite crucible is heated using a gradient heating and holding process. Specifically, the temperature is increased to 800℃ at a rate of 5℃ / min and held for 1 hour; then increased to 1200℃ at a rate of 3℃ / min and held for 2 hours; finally, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 6 hours to complete the vacuum high-temperature reduction. A segmented condenser is used to condense the beryllium vapor generated during reduction. The temperature of the first-stage condenser is 550℃, and the temperature of the second-stage condenser is 300℃. Primary crude beryllium with a purity of 95.5% is collected.

[0044] Step 6, Secondary Reduction: Weigh out 10% of the mass of the primary crude beryllium, mix it thoroughly with the primary crude beryllium, and then put it back into a graphite crucible. Keep it at 1450℃ and 1 Pa vacuum for 2 hours. After cooling, you will get secondary crude beryllium with a purity of 98.5%.

[0045] Step 7, Refining and Purification: Prepare a mixed pickling solution with a mass fraction of 7% hydrochloric acid and 1% hydrofluoric acid. Place the secondary crude beryllium into the mixed solution and sonicate at 60℃ for 40 minutes to remove surface impurities. Place the pickled crude beryllium in a vacuum furnace and vacuum remelt it for 1 hour at 1450℃ and a vacuum degree of 0.5 Pa. After remelting, purify it with 99.999% high-purity argon gas for protective cooling to obtain the finished metallic beryllium.

[0046] The finished beryllium metal was tested and found to have a purity of 99.6%, a beryllium reduction rate of 93.8%, and impurity contents of 0.25% Si, 0.12% Ca, and 0.04% Fe.

[0047] Example 3 Step 1: Raw material pretreatment: 99.5% purity beryllium oxide with a particle size of 300 mesh was vacuum dried at 155℃ for 3.5 hours; 99% purity industrial silicon powder with a particle size of 300 mesh and 98% purity calcium fluoride with a particle size of 300 mesh were vacuum dried at 125℃ for 2.5 hours respectively. After cooling, all three raw materials were placed in a desiccator for later use. The moisture content of the dried beryllium oxide was found to be 0.05%, the industrial silicon powder 0.03%, and the calcium fluoride 0.04%.

[0048] Step 2, Ingredient Mixing: Weigh the pretreated raw materials according to the molar ratio of beryllium oxide: industrial silicon powder: calcium fluoride = 2:2.0:0.7, put them into a grinding equipment and mix and grind them until uniform. Then pass them through a 190-mesh sieve to remove coarse particles that are not uniformly ground.

[0049] Step 3: Pellet Preparation: The sieved mixture was pressed into pellets with a particle size of 5 mm using a pressure of 10 MPa. The pellets were placed in a vacuum environment and dried at 180℃ for 4 hours, then sintered at 630℃ for 1.5 hours. After cooling, a pellet with a density of 2.05 g / cm³ was obtained. 3Sintered pellets with a porosity of 4.5%.

[0050] Step 4: Loading and Vacuuming: Evenly load the sintered pellets into the graphite crucible of the vacuum distillation furnace and seal the furnace body. Use a two-stage vacuum system consisting of a rotary vane vacuum pump and a diffusion pump to evacuate the furnace. First, evacuate the furnace to a vacuum level of 50 Pa, then continue evacuating to 1 Pa, and maintain the vacuum state for later use.

[0051] Step 5, Primary Reduction: The graphite crucible is heated using a gradient heating and holding process. Specifically, the temperature is increased to 750℃ at a rate of 4℃ / min and held for 1.5 hours; then increased to 1150℃ at a rate of 2.5℃ / min and held for 2.5 hours; finally, the temperature is increased to 1420℃ at a rate of 1.5℃ / min and held for 7 hours to complete the vacuum high-temperature reduction. A segmented condenser is used to condense the beryllium vapor generated during reduction. The temperature of the first-stage condenser is 500℃, and the temperature of the second-stage condenser is 250℃. Primary crude beryllium with a purity of 95.2% is collected.

[0052] Step 6, Secondary Reduction: Weigh out 7.5% of the mass of the primary crude beryllium, mix it thoroughly with the primary crude beryllium, and then put it back into a graphite crucible. Keep it at 1420℃ and 1 Pa vacuum for 2.5 h. After cooling, secondary crude beryllium with a purity of 98.2% is obtained.

[0053] Step 7, Refining and Purification: Prepare a mixed pickling solution of 6% hydrochloric acid and 0.8% hydrofluoric acid by mass. Place the secondary crude beryllium into the mixed solution and sonicate at 55°C for 50 minutes to remove surface impurities. Place the pickled crude beryllium in a vacuum furnace and vacuum remelt at 1430°C and a vacuum degree of 0.5 Pa for 1.5 hours. After remelting, purify it with 99.999% high-purity argon gas for protective cooling to obtain the finished metallic beryllium.

[0054] The finished beryllium metal was tested and found to have a purity of 99.3%, a beryllium reduction rate of 92.4%, and impurity contents of 0.35% Si, 0.20% Ca, and 0.06% Fe.

[0055] This invention provides a method for preparing metallic beryllium based on the Pidgeon process using vacuum silicothermic reduction, and the resulting metallic beryllium. Using high-purity beryllium oxide, industrial silicon powder, and calcium fluoride as raw materials, and relying on a two-stage vacuum distillation furnace, the integrated process of ultrapure raw material pretreatment, high-proportion reducing agent formulation, high-pressure ball sintering, gradient-heating high-vacuum reduction, segmented condensation, secondary reduction, and vacuum remelting purification effectively enhances the reaction kinetics of beryllium oxide reduction, successfully increasing the metallic beryllium reduction rate to over 90%, significantly improving raw material utilization and production efficiency. Simultaneously, through ultrapure raw material control and segmented condensation, efficient separation of beryllium from impurities is achieved. Combined with multiple purification processes including acid washing and vacuum remelting, high-purity metallic beryllium preparation is realized. The finished product meets purity standards and impurity content is precisely controlled, fully satisfying the quality requirements of various fields for metallic beryllium.

[0056] The foregoing descriptions have outlined some exemplary embodiments of the present invention. It is understood that these embodiments are merely illustrative and do not constitute a limitation on the scope of protection of the present invention. Features in these embodiments can be rearranged in suitable ways, and the resulting solutions remain within the scope of protection claimed by the present invention. All other embodiments obtained by those skilled in the art based on the foregoing embodiments without inventive effort, i.e., all modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction, characterized in that, Includes the following steps: Step 1, Raw material pretreatment: Vacuum dry beryllium oxide, industrial silicon powder and calcium fluoride separately, cool and place them in a desiccator for later use; Step 2, Ingredient Mixing: Mix and grind the dried beryllium oxide, industrial silicon powder and calcium fluoride in a molar ratio of 2:(1.8-2.2):(0.6-0.8) and then sieve. Step 3, Pellet Preparation: The sieved mixture is pressed into pellets with a particle size of 3-8 mm. Under vacuum conditions, the pellets are first dried at 150-200℃ for 3-5 hours, and then sintered at 600-650℃ for 1-2 hours to obtain a density ≥2.0 g / cm³. 3 sintered pellets; Step 4, Loading and Vacuuming: Load the sintered pellets into the graphite crucible of the vacuum distillation furnace. After sealing the furnace, first evacuate the vacuum inside the furnace to ≤50Pa, and then evacuate it to ≤1Pa. Step 5, Primary Reduction: A gradient heating crucible is used to perform vacuum high-temperature reduction on the sintered pellets; then a segmented condenser is used to condense the beryllium vapor obtained from the high-temperature reduction to obtain primary crude beryllium. Step 6, Secondary Reduction: After mixing the primary crude beryllium with industrial silicon powder, it is placed back into a graphite crucible and kept at 1380-1450℃ and vacuum degree ≤1Pa for 2-3 hours to obtain secondary crude beryllium; Step 7, Refining and Purification: After acid washing, vacuum remelting, and cooling under inert gas protection, the secondary crude beryllium is obtained as metallic beryllium.

2. The method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction according to claim 1, characterized in that, In step 1, beryllium oxide is vacuum dried at 150-160℃ for 3-4 hours, and industrial silicon powder and calcium fluoride are vacuum dried at 120-130℃ for 2-3 hours respectively. The moisture content of the dried beryllium oxide, industrial silicon powder and calcium fluoride is ≤0.05%. The purity of beryllium oxide is ≥99.5%, the purity of industrial silicon powder is ≥99%, the purity of calcium fluoride is ≥98%, and the particle size of beryllium oxide, industrial silicon powder and calcium fluoride is ≤300 mesh.

3. The method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction according to claim 1, characterized in that, In step 2, the beryllium oxide, industrial silicon powder and calcium fluoride are mixed, ground and then passed through a 180-200 mesh sieve.

4. The method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction according to claim 1, characterized in that, In step 3, the pressure of pressing the spheres is 8-12 MPa, and the porosity of the spheres is ≤5%.

5. The method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction according to claim 1, characterized in that, In step 4, a two-stage vacuum system is used to evacuate the vacuum. The two-stage vacuum system includes a rotary vane vacuum pump and a diffusion pump.

6. The method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction according to claim 1, characterized in that, In step 5, the specific parameters for the gradient heating and holding process are as follows: heating at 3-5℃ / min to 700-800℃ and holding for 1-2 hours; heating at 2-3℃ / min to 1100-1200℃ and holding for 2-3 hours; heating at 1-2℃ / min to 1380-1450℃ and holding for 6-8 hours; the segmented condensation device includes a primary condensation zone and a secondary condensation zone, the temperature of the primary condensation zone is 450-550℃, and the temperature of the secondary condensation zone is 200-300℃.

7. The method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction according to claim 1, characterized in that, In step 6, the amount of industrial silicon powder added is 5-10% of the mass of the primary crude beryllium, the purity of the primary crude beryllium is ≥95%, and the purity of the secondary crude beryllium is ≥98%.

8. The method for preparing metallic beryllium based on the Pidgeon process using vacuum silicon thermal reduction according to claim 1, characterized in that, In step 7, the pickling is performed using a mixture of 5-7% hydrochloric acid and 0.5-1% hydrofluoric acid, and ultrasonically for 40-60 minutes at 50-60℃; the vacuum remelting temperature is 1400-1450℃, the vacuum degree is ≤0.5Pa, and the remelting time is 1-2 hours; the inert gas is high-purity argon with a purity ≥99.999%.

9. A metallic beryllium prepared by any one of the methods described in claims 1-8.

10. The beryllium metal according to claim 9, characterized in that, The purity of the beryllium metal is ≥99%, and the impurities include Si≤0.5%, Ca≤0.3%, and Fe≤0.1%.

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