A method for purifying metallic beryllium

Abstract

The present invention discloses a method for purifying metallic beryllium, which comprises: step 1), using metallic tin as a metal trapping agent, mixing industrial metallic beryllium and metallic tin, and then smelting in an inert atmosphere to form two liquid phase layers, the upper part is liquid beryllium, and the lower part is liquid tin, so that the impurities in the industrial metallic beryllium are enriched in tin; step 2), controlling the temperature to slowly decrease, so that the upper liquid phase beryllium is gradually solidified, and a small amount of metallic tin remaining in the beryllium is removed, and the removed liquid metallic tin returns to the lower liquid tin layer; step 3), when the temperature is lowered to 232-300°C, taking out the solidified metallic beryllium ingot and pickling it to remove the surface oxide, to obtain a purified metallic beryllium product, the purity of which is 1-2 orders of magnitude higher than that of industrial metallic beryllium. The method of the present invention can remove impurities in depth, and is simple to operate, has a short process flow, is less difficult to implement, and is easy to apply on a large scale.

Description

Technical Field

[0001] The invention belongs to the technical field of beryllium metallurgy, and in particular relates to a method for purifying metallic beryllium. Background Art

[0002] Beryllium metal has excellent physical and chemical properties such as low density, high specific stiffness, specific heat capacity, thermal conductivity, corrosion resistance, and excellent nuclear performance. Beryllium metal is used to prepare satellite frame parts and structures, satellite mirrors, rocket nozzles, gyroscopes and navigation and weapon control components, electronic packaging, data communication systems, and mirrors of high-power lasers; Beryllium metal is also used in nuclear fission and fusion reactors. The main application is in X-ray tubes and some beam tubes (windows) in the field of high-energy physics. High-purity beryllium (above 4N) is mainly used as an MBE source to prepare precision devices such as tangential incidence telescopes and X-ray microscopes.

[0003] The process for producing metallic beryllium in my country is the beryllium fluoride magnesium thermal reduction method. The purity of beryllium in the obtained product is generally not higher than 99%, and the main impurity is magnesium. At present, the methods for preparing high-purity beryllium from industrial metallic beryllium include vacuum distillation and molten salt electrolysis. The vacuum distillation method needs to overcome the problem that the oxide layer on the surface of metallic beryllium hinders the diffusion of volatile impurities into the gas phase. For non-volatile impurities (such as iron, manganese, chromium, nickel, copper, aluminum, silicon, etc.), it is difficult to separate them from beryllium through vacuum distillation, and this method has high requirements for equipment and devices; while the molten salt electrolysis method has a long process, cumbersome operation, and low production capacity, and is not suitable for large-scale application.

[0004] Therefore, it is necessary to develop a new clean, green, economical and efficient method for purifying metallic beryllium to achieve independent supply of high-performance beryllium materials. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a clean, green, economical and efficient method for purifying metallic beryllium.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] A method for purifying metallic beryllium, comprising:

[0008] Step 1), industrial metal beryllium and a metal collector (metal tin) are mixed and smelted in an inert atmosphere to form two liquid phase layers, the upper part is liquid beryllium and the lower part is liquid tin, so that the impurities in the industrial metal beryllium are enriched in the tin;

[0009] Step 2), controlling the temperature to slowly decrease, so that the small amount of metal tin remaining in the upper liquid phase beryllium can be removed during the gradual solidification process, and the removed liquid metal tin returns to the lower liquid tin layer;

[0010] Step 3), cooling to 232-300°C, taking out the solidified metal beryllium ingot and pickling it to remove the surface oxide, thus obtaining a purified metal beryllium product, the purity of which can be increased by 1-2 orders of magnitude compared with industrial metal beryllium.

[0011] Furthermore, after taking out the purified metal beryllium product, the liquid metal tin is poured out and recovered. The recovered crude tin can be directly recycled to step 1), or it can be recycled to step 1) after refining and impurity removal.

[0012] Preferably, the refining and impurity removal process of the recovered crude tin is: adding ammonium chloride and stirring to remove aluminum → condensation to remove iron and silicon → vacuum volatilization to remove magnesium, calcium, zinc and lead to obtain refined tin, and circulating to step 1).

[0013] The step 1) should be carried out in an inert atmosphere. This is because even if a small amount of O is dissolved in the Be phase, the melting point of Be will be greatly increased and high melting point oxides will be mixed in the melt, which is not conducive to the precise temperature control and beryllium tin stratification of the pure beryllium precipitation step. Therefore, the heating equipment used should meet the requirements of the inert atmosphere conditions.

[0014] Preferably, the industrial metal beryllium is beryllium beads or beryllium grains with a purity of 90wt%-99wt% and a particle size of less than 3cm.

[0015] Preferably, the metal collector is metallic tin with a purity higher than 99 wt%.

[0016] Preferably, the mass ratio of industrial metal beryllium to tin in the raw material is 1:(1-5). The two can be added to the charging crucible in any manner. More preferably, the industrial metal beryllium and tin are mixed evenly and then added to the charging crucible, which is conducive to full contact between beryllium and tin and promotes tin to capture impurity elements in the beryllium phase.

[0017] Preferably, in step 1), the material of the loading crucible is magnesium oxide, aluminum oxide or beryllium oxide.

[0018] Preferably, in step 1), the smelting equipment used is an induction furnace. Induction heating can stir the molten metal, making the beryllium and tin contact more fully, which is conducive to the migration of impurities in beryllium into tin.

[0019] Preferably, in step 1), the smelting temperature is controlled at 1300-1500° C. and kept at this temperature for 20-120 min.

[0020] Preferably, in step 2), the temperature is first cooled at a rate of 10-30°C / min. When the temperature drops to 1289± (10-100)°C, the cooling rate within this range is 0.1-2°C / min. During the solidification of metallic beryllium, the solubility of tin in the beryllium phase decreases to close to 0, and the trace amount of tin dissolved in the beryllium phase returns to the tin phase. Moreover, since the density of melted beryllium is much lower than that of tin (Be: 1.690 g / cm 3 , Sn: 6.990g / cm 3 ), it is easy to achieve the separation of beryllium and tin phases, and pure beryllium solidifies in the upper layer of the melt. A sufficiently small cooling rate near the solidification point of metallic beryllium can further improve the separation coefficient of beryllium and tin, and avoid physical doping between the two phases caused by excessive condensation of beryllium. Outside this temperature range, a faster cooling rate can be adopted according to the thermal shock resistance of the charging crucible, and the cooling rate can be controlled to 10-30℃ / min, which can shorten the process flow and reduce energy consumption.

[0021] Preferably, in step 3), the cooling rate is 10-30°C / min.

[0022] Preferably, in step 3), the metal beryllium ingot is immersed in H + Acid pickling is performed in 0.05-0.5 mol / L hydrochloric acid, sulfuric acid or nitric acid for 10-30 minutes.

[0023] The metal beryllium purification method of the present invention uses tin as an impurity metal capture agent, and smelts it together with industrial metal beryllium in an induction furnace. After the metal beryllium and tin are melted, two liquid phases are formed, the upper layer is liquid beryllium, and the lower layer is liquid tin. According to the difference in solubility of impurities in the beryllium phase and the tin phase, the impurities in the beryllium migrate to the tin. In the cooling stage, when the temperature is near the solidification point of beryllium, slow cooling (0.1-2°C / min) should be adopted, so that the upper liquid phase beryllium gradually solidifies, and the small amount of metal tin remaining in the beryllium returns to the lower liquid tin layer and is removed. At the same time, slow cooling can avoid physical doping between beryllium and tin. After the metal beryllium is completely solidified, a faster cooling rate (10-30°C / min) can be appropriately adopted to cool to 232-300°C. The solidified metal beryllium is taken out and pickled to remove the surface oxide, and a purified metal beryllium product is obtained. The liquid metal tin is poured out and recovered, and the obtained crude tin can be directly recycled to the smelting step, or it can be recycled to the smelting step after refining and impurity removal.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] 1. Compared with the vacuum distillation method, the metal beryllium purification method of the present invention not only has a significant removal effect on volatile impurities such as Mg and Ca, but also can achieve deep removal of non-volatile impurities (such as Fe, Mn, Cr, Ni, Al, Si, etc.).

[0026] 2. Compared with the molten salt electrolysis method, the metal beryllium purification method of the present invention is simple to operate, has a short process flow, is less difficult to implement, and is easy to apply on a large scale.

[0027] 3. The metal beryllium purification method of the present invention realizes the recycling regeneration of the metal capture agent, and there is no loss of beryllium in the process. It is a clean, green, economical and efficient metal beryllium purification method. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The figure is a process flow chart of the method for purifying metal beryllium of the present invention. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0031] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] The purity of industrial metal beryllium in the raw materials used in the following examples is 98.601 wt %, the impurity composition is shown in Table 1, and the purity of metal tin is 99.99 wt %.

[0034] Table 1 Main impurities and contents in industrial metal beryllium

[0035]

[0036] Embodiment 1:

[0037] like Figure 1 As shown, a method for purifying metallic beryllium comprises the following steps:

[0038] Step 1: 1.5 g of industrial metal beryllium with a particle size of less than 2 mm and 7.5 g of metal tin are placed in a magnesium oxide crucible with a diameter of 16 mm. In an argon atmosphere, the crucible is heated to 1500° C. and kept warm for 120 minutes for melting. After the metal is melted, two liquid phase layers are formed, with the upper portion being liquid beryllium and the lower portion being liquid tin.

[0039] Step 2: lower the temperature to 1389°C at a rate of 20°C / min, and then to 1189°C at a rate of 1°C / min. Pure beryllium is precipitated on the upper layer, and a small amount of metallic tin remaining in the beryllium is removed. The removed liquid metallic tin returns to the lower liquid tin layer.

[0040] Step 3: Cool the temperature to 250°C at a rate of 20°C / min, separate the solidified metal beryllium ingot from the tin liquid, and + High-purity beryllium was obtained by pickling the surface with hydrochloric acid at a concentration of 0.5 mol / L.

[0041] Step 4: Pour out the liquid tin (crude tin) in the crucible and recycle it for later use.

[0042] The purification effect of metal beryllium in this embodiment is as follows:

[0043] The total amount of impurities in high-purity beryllium is detected to be 0.052wt%, the purity of beryllium is 99.948wt%, and the main impurities and their contents are shown in Table 2.

[0044] Table 2 Main impurities and contents in high-purity beryllium obtained in Example 1

[0045]

[0046] Embodiment 2:

[0047] like Figure 1 As shown, a method for purifying metallic beryllium comprises the following steps:

[0048] Step 1: 1.5 g of industrial metal beryllium with a particle size of less than 5 mm and 1.5 g of metal tin are placed in a magnesium oxide crucible with a diameter of 16 mm, and heated to 1300° C. for 20 minutes in an argon atmosphere to form two liquid phase layers after the metal is melted, with the upper portion being liquid beryllium and the lower portion being liquid tin.

[0049] Step 2: lower the temperature to 1389°C at a rate of 10°C / min, and then to 1189°C at a rate of 1°C / min. Pure beryllium is precipitated on the upper layer, and a small amount of metallic tin remaining in the beryllium is removed. The removed liquid metallic tin returns to the lower liquid tin layer.

[0050] Step 3: Cool the temperature to 250°C at a rate of 10°C / min, separate the solidified metal beryllium ingot from the tin liquid, and +High-purity beryllium was obtained by pickling the surface with 0.1 mol / L nitric acid.

[0051] Step 4: Pour out the liquid tin (crude tin) in the crucible and recycle it for later use.

[0052] The purification effect of metal beryllium in this embodiment is as follows:

[0053] The total amount of impurities in high-purity beryllium is detected to be 0.276wt%, the purity of beryllium is 99.724wt%, and the main impurities and their contents are shown in Table 3.

[0054] Table 3 Main impurities and contents in high-purity beryllium obtained in Example 2

[0055]

[0056] Embodiment 3:

[0057] like Figure 1 As shown, a method for purifying metallic beryllium comprises the following steps:

[0058] Step 1: 1.5 g of industrial metal beryllium with a particle size of less than 1 mm and 6 g of metal tin are placed in a magnesium oxide crucible with a diameter of 16 mm. In an argon atmosphere, the crucible is heated to 1400° C. and kept warm for 60 minutes for smelting. After the metal is melted, two liquid phase layers are formed, with the upper portion being liquid beryllium and the lower portion being liquid tin.

[0059] Step 2: lower the temperature to 1299°C at a rate of 30°C / min, and then to 1279°C at a rate of 0.1°C / min. Pure beryllium is precipitated on the upper layer, and a small amount of metallic tin remaining in the beryllium is removed. The removed liquid metallic tin returns to the lower liquid tin layer.

[0060] Step 3: Cool the temperature to 300°C at a rate of 30°C / min, separate the solidified beryllium ingot from the tin liquid, and + High-purity beryllium was obtained by pickling the surface with sulfuric acid at a concentration of 0.1 mol / L.

[0061] Step 4: Pour out the liquid tin (crude tin) in the crucible and recycle it for later use.

[0062] The purification effect of metal beryllium in this embodiment is as follows:

[0063] The total amount of impurities in high-purity beryllium is detected to be 0.100wt%, the purity of beryllium is 99.900wt%, and the main impurities and their contents are shown in Table 4.

[0064] Table 4 Main impurities and contents in high-purity beryllium obtained in Example 3

[0065]

[0066] Embodiment 4:

[0067] like Figure 1 As shown, a method for purifying metallic beryllium comprises the following steps:

[0068] Step 1: 1.5 g of industrial metal beryllium with a particle size of less than 2 mm and 6.0 g of metal tin are placed in a magnesium oxide crucible with a diameter of 16 mm, and heated to 1400° C. for 60 minutes in an argon atmosphere to form two liquid phase layers after the metal is melted, with the upper portion being liquid beryllium and the lower portion being liquid tin.

[0069] Step 2: lower the temperature to 1339°C at a rate of 20°C / min, and then to 1239°C at a rate of 2°C / min. Pure beryllium is precipitated on the upper layer, and a small amount of metallic tin remaining in the beryllium is removed. The removed liquid metallic tin returns to the lower liquid tin layer.

[0070] Step 3: Cool the temperature to 235°C at a rate of 20°C / min, separate the solidified metal beryllium ingot from the tin liquid, and + High-purity beryllium was obtained by pickling the surface with hydrochloric acid at a concentration of 0.05 mol / L.

[0071] Step 4: Pour out the liquid tin (crude tin) in the crucible and recycle it for later use.

[0072] The purification effect of metal beryllium in this embodiment is as follows:

[0073] The total amount of impurities in high-purity beryllium is detected to be 0.209wt%, the purity of beryllium is 99.791wt%, and the main impurities and their contents are shown in Table 5.

[0074] Table 5 Main impurities and contents in high-purity beryllium obtained in Example 4

[0075]

[0076] Comparative Example 1:

[0077] A method for purifying metallic beryllium comprises the following steps:

[0078] Step 1: 1.5 g of industrial metal beryllium with a particle size of less than 2 mm and 6.0 g of metal tin are placed in a magnesium oxide crucible with a diameter of 16 mm. In an argon atmosphere, the crucible is heated to 1290° C. and then kept warm for 10 minutes for melting. After the metal is melted, two liquid phase layers are formed, with the upper portion being liquid beryllium and the lower portion being liquid tin.

[0079] Step 2: lower the temperature to 1250° C. at a rate of 0.2° C. / min, so that the upper liquid phase beryllium gradually solidifies, pure beryllium is precipitated in the upper layer, and the removed liquid metal tin returns to the lower liquid tin layer.

[0080] Step 3: Cool the temperature to 250° C. at a rate of 30° C. / min, separate the solidified metal beryllium ingot from the tin liquid, and pickle the surface with 0.1 mol / L hydrochloric acid to obtain a beryllium ingot.

[0081] Step 4: Pour out the liquid tin in the crucible and recycle it for later use.

[0082] The purification effect of metal beryllium in this comparative example is as follows:

[0083] The total amount of metallic beryllium impurities in the upper layer was detected to be 1.047wt%, and the purity of beryllium was 98.953wt%. The main impurities and their contents are shown in Table 6.

[0084] In this comparative example, the metallic beryllium and tin were not fully smelted, and the impurities in the metallic beryllium could not fully migrate to the tin, resulting in the purity of the upper layer of beryllium in the product being only 98.953wt%, indicating that the purification of beryllium in this method requires smelting with tin.

[0085] Table 6 Main impurities and contents in beryllium ingot obtained in Comparative Example 1

[0086]

[0087] Comparative Example 2:

[0088] A method for purifying metallic beryllium comprises the following steps:

[0089] Step 1: 1.5 g of industrial metal beryllium with a particle size of less than 2 mm and 6.0 g of metal tin are placed in a magnesium oxide crucible with a diameter of 16 mm, and heated to 1400° C. for 60 minutes in an argon atmosphere to form two liquid phase layers after the metal is melted, with the upper portion being liquid beryllium and the lower portion being liquid tin.

[0090] Step 2: Lower the temperature to 1310°C at a rate of 30°C / min, and then lower it to 1250°C at a rate of 5°C / min to solidify the metal beryllium.

[0091] Step 3: Cool the temperature to 250° C. at a rate of 30° C. / min, separate the solidified metal beryllium ingot from the tin liquid, and pickle the surface with 0.1 mol / L hydrochloric acid to obtain a beryllium ingot.

[0092] Step 4: Pour out the liquid tin in the crucible and recycle it for later use.

[0093] The purification effect of metal beryllium in this comparative example is as follows:

[0094] The total amount of metallic beryllium impurities in the upper layer was detected to be 2.954wt%, and the purity of beryllium was 97.046wt%. The main impurities and their contents are shown in Table 7.

[0095] Compared with Example 3, the cooling rate in the pure beryllium precipitation step of this comparative example is too fast, which is 5°C / min, so that more tin is mixed in the beryllium, resulting in the purity of the upper layer of beryllium in the product being only 97.046wt%, which is lower than the 99.90wt% purity of the metallic beryllium in Example 3, indicating that the cooling rate in the pure beryllium precipitation step cannot be too fast.

[0096] Table 7 Main impurities and contents in beryllium ingot obtained in Comparative Example 2

[0097]

[0098] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for purifying metallic beryllium, characterized in that: include: Step 1), using metallic tin as a metal capture agent, mixing industrial metallic beryllium and metallic tin and smelting them in an inert atmosphere at a smelting temperature of 1400-1500°C for 20-120 minutes to form two liquid phase layers, the upper portion being liquid beryllium and the lower portion being liquid tin, so that impurities in the industrial metallic beryllium are enriched in the tin; Step 2), controlling the temperature to decrease so that the metal tin remaining in the beryllium can be removed during the gradual solidification of the upper liquid phase beryllium, and the removed liquid metal tin returns to the lower liquid tin layer; wherein, the temperature is controlled to decrease at a cooling rate of 10-30°C / min, and when the temperature drops to the range of 1289±(10-100)°C, the cooling rate within the range is 0.1-2°C / min; Step 3), cooling to 232-300°C, taking out the solidified metal beryllium ingot and pickling it to remove the surface oxide, thereby obtaining a purified metal beryllium product, the purity of which is 1-2 orders of magnitude higher than that of industrial metal beryllium.

2. The method for purifying metallic beryllium according to claim 1, characterized in that: The industrial metal beryllium is beryllium beads or beryllium grains with a purity of 90wt%-99wt% and a particle size of less than 3cm.

3. The method for purifying metallic beryllium according to claim 1, characterized in that: The purity of the metallic tin used as the metal collector is higher than 99wt%.

4. The method for purifying metallic beryllium according to claim 1, characterized in that: The mass ratio of the industrial metal beryllium to the metal tin used as a metal collector is 1:(1-5).

5. The method for purifying metallic beryllium according to claim 1, characterized in that: In the step 1), a crucible is used for loading, and the material of the crucible is magnesium oxide, aluminum oxide or beryllium oxide.

6. The method for purifying metallic beryllium according to claim 1, characterized in that: In step 3), the metal beryllium ingot is immersed in H + Acid pickling is performed in 0.05-0.5 mol / L hydrochloric acid, sulfuric acid or nitric acid for 10-30 minutes.

7. The method for purifying metallic beryllium according to claim 1, characterized in that: The method further comprises: after taking out the purified metal beryllium product, pouring out the liquid metal tin and recovering it.

8. The method for purifying metallic beryllium according to claim 7, characterized in that: The recovered metallic tin is directly recycled or recycled to step 1) after being refined and impurity-removed for use as a metal capture agent.

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