Preparation method of beta-type beryllium hydroxide crystal

Abstract

The invention belongs to the technical field of metal compound extraction, and particularly relates to a preparation method of a beta-type beryllium hydroxide crystal. According to the preparation method provided by the invention, a precipitation reaction does not need to be carried out under a high-temperature boiling condition, cyclic precipitation is carried out under a low-temperature condition, a product of a previous precipitation reaction is used as a seed crystal, and during a next precipitation reaction, because the solubility of micro crystals is larger than that of coarse-particle crystals, the micro crystals are promoted to be dissolved, and the solution concentration is increased; substances in the solution continue to be separated out on large-particle crystals, large crystal grains continuously grow up, finally coarse-particle crystals required by the industry are formed, the consumption of ammonia water is reduced by 70% or above, obtained alpha-type beryllium hydroxide precipitates are subjected to subsequent sodium hydroxide solution alkali washing and heat treatment, impurities are removed while post-crystal-form conversion is conducted, and beta-type beryllium hydroxide is obtained. According to the method, the harm of ammonia volatilization to operators is reduced, the energy consumption can be reduced, and the cost is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal compound extraction, and in particular relates to a method for preparing beta-type beryllium hydroxide crystals. Background Art

[0002] Beryllium is an amphoteric metal that is soluble in both acid and alkali and has the advantages of high strength and high elastic modulus. As an important material, beryllium can be used in the nuclear industry, aviation, electronics industry, optical devices, machinery manufacturing and other industries.

[0003] Beryllium-containing ores mainly include beryl (3BeO·Al2O3·6SiO2), chrysoberyl (2BeO·SiO2), chrysoberyl (BeO·Al2O3), etc. In the production and smelting process of beryllium, beryllium hydroxide is an indispensable intermediate product. Usually, the beryllium ore leaching solution is subjected to a series of impurity removal processes and then ammonia water is added for high-temperature boiling precipitation to obtain a β-type beryllium hydroxide precipitation slurry containing impurities. The precipitation slurry is subjected to solid-liquid separation, and then sodium hydroxide is used for alkaline washing to remove impurities, and then solid-liquid separation is performed again to obtain β-type beryllium hydroxide. In the existing beryllium hydroxide precipitation process, energy consumption is high, ammonia water consumption is extremely large, and the large amount of ammonia water volatilization increases the risk factor of the operating position. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing beta-type beryllium hydroxide crystals. The preparation method provided by the present invention can significantly reduce the consumption of ammonia water.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing β-type beryllium hydroxide crystals, comprising the following steps:

[0007] The first beryllium ore leaching solution and the first ammonia water are first mixed to perform a first precipitation reaction to obtain a first α-type beryllium hydroxide;

[0008] Repeating the first mixing and first precipitation reaction 2 to 25 times, the raw materials for each mixing and precipitation reaction include beryllium ore leaching solution, ammonia water and α-type beryllium hydroxide obtained in the previous precipitation reaction;

[0009] The concentration of beryllium oxide in the first beryllium ore leachate and the beryllium ore leachate is independently 15-30 g / L; the ratio of the total volume of the first beryllium ore leachate and the beryllium ore leachate to the total volume of the first ammonia water and the ammonia water is 10-6.7:1; the temperature of the first precipitation reaction is 25-70° C.;

[0010] The α-type beryllium hydroxide obtained from the last precipitation reaction is mixed with a sodium hydroxide solution and subjected to crystal transformation to obtain the β-type beryllium hydroxide crystal.

[0011] Preferably, the pH values ​​of the first beryllium ore leachate and the beryllium ore leachate are independently 2-6; the concentrations of alumina in the first beryllium ore leachate and the beryllium ore leachate are independently 0.01-0.2 g / L, and the concentrations of fluoride ions are independently 0.1-0.5 g / L.

[0012] Preferably, the concentrations of the first aqueous ammonia and the aqueous ammonia are independently 25% to 30%; and the pH value of the reaction system obtained by the first mixing is 5 to 9.

[0013] Preferably, the first precipitation reaction time is 0.1 to 2.5 hours.

[0014] Preferably, the concentration of the sodium hydroxide solution is 40-100 g / L; the mass ratio of α-type beryllium hydroxide in the sodium hydroxide solution to the α-type beryllium hydroxide obtained in the last precipitation reaction is 0.3-1.3:1, calculated as beryllium oxide.

[0015] Preferably, the temperature of the crystal transformation is 80-150° C., and the time is 0.5-3 h.

[0016] Preferably, the crystal transformation further includes dilution and heat treatment performed sequentially.

[0017] Preferably, the diluting reagent is water; the mass ratio of α-type beryllium hydroxide to beryllium oxide in the α-type beryllium hydroxide obtained in the last precipitation reaction is 23420-47000:1.

[0018] Preferably, the heat treatment is carried out at a temperature of 70 to 150° C. and for a time of 0.1 to 2 hours.

[0019] Preferably, the last precipitation reaction further includes solid-liquid separation; the solid-liquid separation includes suction filtration, filter pressing or centrifugal treatment.

[0020] The invention provides a method for preparing beta-type beryllium hydroxide crystals, comprising the following steps: first mixing a first beryllium ore leachate and a first ammonia water, performing a first precipitation reaction, and obtaining a first alpha-type beryllium hydroxide; repeating the first mixing and the first precipitation reaction 2 to 25 times, wherein the raw materials for each mixing and precipitation reaction include the beryllium ore leachate, the ammonia water, and the alpha-type beryllium hydroxide obtained in the last precipitation reaction; the concentration of beryllium oxide in the first beryllium ore leachate and the beryllium ore leachate is independently 15 to 30 g / L; the ratio of the total volume of the first beryllium ore leachate and the beryllium ore leachate to the total volume of the first ammonia water and the ammonia water is 10 to 6.7:1; the temperature of the first precipitation reaction is 25 to 70 DEG C; the alpha-type beryllium hydroxide obtained in the last precipitation reaction is mixed with a sodium hydroxide solution, and crystal form conversion is performed to obtain the beta-type beryllium hydroxide crystals. The preparation method provided by the present invention does not need to carry out precipitation reaction under high temperature boiling conditions, but carries out multiple cycles of precipitation under low temperature conditions, uses the last precipitation as a crystal seed, and in the next precipitation, because the solubility of the tiny crystals is greater than that of the coarse-grained crystals, the tiny crystals are promoted to dissolve, the solution concentration is increased, the substances in the solution continue to precipitate on the large-grained crystals, the large crystals continue to grow, and finally form the coarse-grained crystals required by the industry, and the ammonia consumption is reduced by more than 70%, and the obtained α-type beryllium hydroxide precipitation is subsequently washed with sodium hydroxide solution, and impurities are removed while the post-crystal transformation is carried out, so as to obtain β-type beryllium hydroxide. The method reduces the harm of ammonia volatilization to operators, can reduce energy consumption, and save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 This is a process flow chart of the cyclic precipitation of beryllium hydroxide according to the present invention;

[0023] Figure 2 is a SEM image of α-type beryllium hydroxide and β-type beryllium hydroxide in Example 1;

[0024] Figure 3 is a SEM image of α-type beryllium hydroxide and β-type beryllium hydroxide in Example 2;

[0025] Figure 4 is a SEM image of α-type beryllium hydroxide and β-type beryllium hydroxide in Example 3;

[0026] Figure 5 is a SEM image of α-type beryllium hydroxide and β-type beryllium hydroxide in Example 4;

[0027] Figure 6 is the volume change curve of the cyclic precipitation in Example 5;

[0028] Figure 7 This is a SEM image of α-type beryllium hydroxide obtained by the 10th precipitation in Example 5;

[0029] Figure 8 This is a SEM image of α-type beryllium hydroxide obtained by the 25th precipitation in Example 5;

[0030] Fig. 9 The SEM images of β-type beryllium hydroxide obtained in Example 5 and Comparative Example 1 are shown;

[0031] Fig.10 The XRD diagrams of the β-type beryllium hydroxide crystals obtained in Comparative Example 1, Example 5 and Example 6;

[0032] Fig.11 The following are SEM images of the β-type beryllium hydroxide crystals obtained in Comparative Example 1 and Example 6. DETAILED DESCRIPTION

[0033] The present invention provides a method for preparing β-type beryllium hydroxide crystals, comprising the following steps:

[0034] The first beryllium ore leaching solution and the first ammonia water are first mixed to perform a first precipitation reaction to obtain a first α-type beryllium hydroxide;

[0035] Repeating the first mixing and first precipitation reaction 2 to 25 times, the raw materials for each mixing and precipitation reaction include beryllium ore leaching solution, ammonia water and α-type beryllium hydroxide obtained in the previous precipitation reaction;

[0036] The concentration of beryllium oxide in the first beryllium ore leachate and the beryllium ore leachate is independently 15-30 g / L; the ratio of the total volume of the first beryllium ore leachate and the beryllium ore leachate to the total volume of the first ammonia water and the ammonia water is 10-6.7:1; the temperature of the first precipitation reaction is 25-70° C.;

[0037] The α-type beryllium hydroxide obtained from the last precipitation reaction is mixed with a sodium hydroxide solution and subjected to crystal transformation to obtain the β-type beryllium hydroxide crystal.

[0038] In the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0039] The present invention first mixes a first beryllium ore leaching solution and a first ammonia water, performs a first precipitation reaction, and obtains a first alpha-type beryllium hydroxide.

[0040] In the present invention, the concentration of beryllium oxide in the first beryllium ore leachate is 15-30 g / L, and in a specific embodiment, it can be 21.35 g / L; the concentration of aluminum oxide is 0.01-0.2 g / L, and in a specific embodiment, it can be 0.082 g / L; the concentration of fluoride ions is 0.1-0.5 g / L, and in a specific embodiment, it can be 0.35 g / L; the pH value is 2-6, and in a specific embodiment, it can be 5.12; the first beryllium ore leachate is a beryllium ore leaching neutralization solution.

[0041] In the present invention, the concentration of the first ammonia water is 25% to 30%, and in a specific embodiment, it can be 28%.

[0042] In the present invention, the pH value of the reaction system obtained by the first mixing is 5-9, and in specific embodiments, it can be 6, 7, 7.5 or 8.

[0043] In the present invention, the temperature of the first precipitation reaction is 25-70°C, and in a specific embodiment, it can be 25°C, 30°C, 40°C, 50°C or 60°C; the time is 0.1-2.5h, and in a specific embodiment, it can be 0.5h, 1h, 1.5h or 2h; the first precipitation reaction is carried out under stirring conditions; the precipitation also includes standing; the standing time is 4-8h, and in a specific embodiment, it can be 4h, 6h or 8h.

[0044] After obtaining the first α-type beryllium hydroxide, the present invention repeats the first mixing and first precipitation reaction 2 to 25 times, and the raw materials for each mixing and precipitation reaction include beryllium ore leaching solution, ammonia water and α-type beryllium hydroxide obtained in the previous precipitation reaction.

[0045] In the present invention, the concentration of beryllium oxide in the beryllium ore leachate is 15-30 g / L, and in a specific embodiment, it can be 21.35 g / L; the concentration of aluminum oxide is 0.01-0.2 g / L, and in a specific embodiment, it can be 0.082 g / L; the concentration of fluoride ions is 0.1-0.5 g / L, and in a specific embodiment, it can be 0.35 g / L; the pH value is 2-6, and in a specific embodiment, it can be 5.12; the beryllium ore leachate is a beryllium ore leaching neutralization solution; the beryllium ore leaching neutralization solution in the present invention is a neutralization solution obtained after the beryllium ore leachate is neutralized to preliminarily remove impurities such as aluminum and iron, and comes from China Minmetals Beryllium Industry Co., Ltd.

[0046] In the present invention, the concentration of the ammonia water is 25% to 30%, and in a specific embodiment, it can be 28%; the ratio of the total volume of the first beryllium ore leachate and the beryllium ore leachate to the total volume of the first ammonia water and the ammonia water is 10 to 6.7:1, and in a specific embodiment, it can be 8:1.

[0047] In the present invention, the conditions of each mixing and precipitation reaction are the same as the first mixing and the first precipitation reaction, and will not be repeated here. The purpose of repeating the precipitation step and performing cyclic precipitation in the present invention is to prepare the coarse crystals required for the above-mentioned industry, so as to facilitate the subsequent process of solid-liquid separation and washing crystals. Therefore, the number of crystal nuclei must be reduced, that is, the supersaturation of the solution must be reduced. In the same system, the solubility of finer crystals is much greater than that of coarse crystals. Coarse crystals are in a saturated state in the solution, while tiny crystals are unsaturated, that is, microcrystals dissolve, which promotes the increase of solution concentration. According to the diffusion effect, the precipitated substances continue to precipitate on the large crystals, and the large crystals grow further. Using the last precipitation slurry as a seed, in the next precipitation, a neutralizing liquid is added to the slurry, and the acidity of the solution is increased at the same time. Because the solubility of tiny crystals is greater than that of coarse crystals, tiny crystals are dissolve, the solution concentration is increased, and large crystals are in a supersaturated state. According to the diffusion principle, substances in the solution continue to precipitate on large crystals, and large crystals continue to grow. In the next equilibrium establishment, microcrystals dissolve, the solution concentration is increased, and coarse crystals continue to grow. The same repetitive process continues, with fine grains continuously dissolving and coarse grains continuously growing larger.

[0048] In the present invention, this step is repeated 2 to 25 times, and in a specific embodiment, it can be 5 times, 10 times, 15 times or 20 times.

[0049] In the present invention, after the last precipitation reaction, solid-liquid separation and drying are also carried out in sequence; the solid-liquid separation includes suction filtration, filter pressing or centrifugal treatment; the filtration includes vacuum filtration or belt filtration; the filter pressing is plate and frame filter pressing; the drying temperature is 40 to 105°C, and in a specific embodiment, it can be 60°C, 80°C or 100°C; the drying time is 4 to 12h, and in a specific embodiment, it can be 6h, 8h or 10h.

[0050] After obtaining the α-type beryllium hydroxide obtained by the last precipitation reaction, the present invention mixes the α-type beryllium hydroxide obtained by the last precipitation reaction with a sodium hydroxide solution to perform crystal transformation to obtain the β-type beryllium hydroxide crystal.

[0051] In the present invention, the concentration of the sodium hydroxide solution is 40-100 g / L, and in a specific embodiment, it can be 50 g / L, 60 g / L, 70 g / L, 80 g / L or 90 g / L; α-type beryllium hydroxide is calculated as beryllium oxide, and the mass ratio of sodium hydroxide in the sodium hydroxide solution and beryllium oxide in the α-type beryllium hydroxide is 0.3-1.3:1, and in a specific embodiment, it can be 0.5:1, 0.7:1, 0.9:1 or 1.1:1.

[0052] In the present invention, the temperature of the crystal transformation is 80-150°C, and in specific embodiments, it can be 90°C, 110°C, 130°C or 140°C; the time is 0.5-3h, and in specific embodiments, it can be 1h, 1.5h, 2h or 2.5h.

[0053] In the present invention, the crystal transformation further includes dilution and heat treatment in sequence; the dilution reagent is water; the mass ratio of α-type beryllium hydroxide to beryllium oxide is 23.42-48:1, and in a specific embodiment, it can be 26:1, 30:1, 34:1, 38:1, 40:1 or 44:1; the heat treatment temperature is 70-150°C, and in a specific embodiment, it can be 90°C, 110°C or 130°C; the time is 0.1-2h, and in a specific embodiment, it can be 0.5h, 1h or 1.5h. In the present invention, the dilution and heat treatment are used to accelerate the hydrolysis of sodium beryllium produced by the dissolution of beryllium hydroxide and form β-type beryllium hydroxide during the heating process.

[0054] In the present invention, the heat treatment further includes solid-liquid separation and drying in sequence; the solid-liquid separation includes suction filtration, filter pressing or centrifugal treatment; the filtration includes vacuum filtration or belt filtration; the filter pressing is plate and frame filter pressing; the solid-liquid separation may also include washing; the washing reagent is water; the temperature of the washing reagent is above 80°C; the drying temperature is 40-105°C, and in a specific embodiment, it can be 60°C, 80°C or 100°C; the drying time is 4-12h, and in a specific embodiment, it can be 6h, 8h or 10h.

[0055] The preparation method provided by the present invention does not need to carry out precipitation reaction under high temperature boiling conditions, but carries out multiple precipitation cycles under low temperature conditions, uses the last precipitation as a crystal seed, and in the next precipitation, because the solubility of the tiny crystals is greater than that of the coarse-grained crystals, the tiny crystals are promoted to dissolve, the solution concentration is increased, the substances in the solution continue to precipitate on the large-grained crystals, the large crystals continue to grow, and finally form the coarse-grained crystals required by the industry, and the ammonia consumption is reduced by more than 70%, and the obtained α-type beryllium hydroxide precipitation is subsequently washed with sodium hydroxide solution, and impurities are removed at the same time as the post-crystal transformation, so as to obtain β-type beryllium hydroxide, and the process flow is shortened to a certain extent. The method reduces the harm of ammonia volatilization to operators, can reduce energy consumption, and save costs.

[0056] In order to further illustrate the present invention, the preparation method of β-type beryllium hydroxide crystals provided by the present invention is described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0057] The pH value of the beryllium ore leaching neutralization solution used in the embodiments of the present invention and the comparative examples is 5.12, and the main components are shown in Table 1.

[0058] Table 1 Main components and contents of beryllium ore leaching neutralization solution (g / L)

[0059] name BeO <![CDATA[Al2O3]]> <![CDATA[F - ]]> Beryllium ore leaching neutralization solution 21.35 0.082 0.35

[0060] Comparative Example 1

[0061] Add ammonia water to the beryllium ore leaching neutralization solution. The amount of ammonia water added per cubic meter of beryllium ore leaching neutralization solution is 0.39-0.53m 3 , high-temperature boiling precipitation is carried out to obtain a beryllium hydroxide precipitation slurry mainly composed of β-type beryllium hydroxide, the precipitation slurry is filtered through a plate and frame filter press and rinsed with hot water (>80°C), after solid-liquid separation, sodium hydroxide solution (62.5g / L) is used together with the beryllium hydroxide precipitate to stir and boil for 1h for secondary impurity removal, and then water is added to dilute, stirred and boiled for 0.5h, and then filtered through a plate and frame filter press again and rinsed with hot water (>80°C) to obtain β-type beryllium hydroxide.

[0062] Example 1

[0063] At a temperature of 30°C, the following cyclic precipitation test was performed:

[0064] The first precipitation: take 200 mL of beryllium ore leaching neutralization solution, put it in a beaker, add 28% ammonia water to adjust the slurry pH to 7.5-8.0, continue stirring for 30 minutes to obtain a slurry, and let it settle for 8 hours.

[0065] Second precipitation: After separating the supernatant from the slurry obtained in the first precipitation, start stirring, add 200 mL of beryllium ore leaching neutralization solution, stir for 30 minutes, then add 28% ammonia water to adjust the slurry pH to 7.5-8.0, continue stirring for 30 minutes to obtain a slurry, and let it settle for 8 hours.

[0066] The 3rd to 6th precipitation: repeat the 2nd precipitation process. The ammonia consumption of the precipitation reaction is shown in Table 2.

[0067] The α-type beryllium hydroxide precipitate slurry obtained from the sixth precipitation was vacuum filtered, dried at 90°C, and then washed with alkali, i.e., 40 mL of 70 g / L sodium hydroxide solution and 6 g of α-type beryllium hydroxide solid were stirred and boiled for 1 hour, then 150 mL of water was added to dilute and boiled for 0.5 hour, and vacuum filtered again while eluting with hot water (>80°C) for solid-liquid separation, and dried at 90°C to obtain β-type beryllium hydroxide crystals.

[0068] 5μm SEM images of the precipitated samples before and after alkali washing are shown in Figure 2 .

[0069] Example 2

[0070] β-type beryllium hydroxide crystals were prepared according to the preparation method described in Example 1, except that the precipitation was carried out at a temperature of 40°C. The ammonia consumption of the precipitation reaction is shown in Table 2. The 5 μm SEM images of the precipitated sample before and after alkali washing are shown in Figure 3 .

[0071] Example 3

[0072] β-type beryllium hydroxide crystals were prepared according to the preparation method described in Example 1, except that the precipitation was carried out at a temperature of 50°C. The ammonia consumption of the precipitation reaction is shown in Table 2. The 5 μm SEM images of the precipitated sample before and after alkali washing are shown in Table 2. Figure 4 .

[0073] Example 4

[0074] β-type beryllium hydroxide crystals were prepared according to the preparation method described in Example 1, except that the precipitation was carried out at a temperature of 60°C. The ammonia consumption of the precipitation reaction is shown in Table 2. The 5 μm SEM images of the precipitated sample before and after alkali washing are shown in Figure 5 .

[0075] From 2 to 5, it can be seen that under different temperature conditions, the change trend of the precipitation volume is basically the same. As the temperature increases, the particle size of the beryllium hydroxide precipitate before alkali washing increases, indicating that the increase in temperature can increase the particle size of the beryllium hydroxide precipitate. At the same time, it can also be seen that these beryllium hydroxide precipitate samples have a disordered crystal form before alkali washing, which is α-type, but after the subsequent alkali washing process, clearly visible large particles of β-type beryllium hydroxide can be obtained.

[0076] Table 2 Ammonia consumption of precipitation reaction of Examples 1 to 4 (unit: mL)

[0077]

[0078]

[0079] In Comparative Example 1, the amount of ammonia consumed for precipitation of each cubic meter of beryllium ore leaching neutralization solution is 0.39-0.53 m 3 As shown in Table 2, the solution provided by the present invention reduces the consumption of ammonia water by 70% by adopting circulating precipitation.

[0080] Example 5

[0081] The first precipitation: at room temperature 25°C, take 500 mL of beryllium ore leaching neutralization solution, put it in a beaker, add 25% ammonia water to adjust the slurry pH to 7.5-8.0, continue stirring for 30 minutes to obtain a slurry, and let it settle for 8 hours.

[0082] Second precipitation: After separating the supernatant from the slurry obtained in the first precipitation, start stirring, add 500mL of beryllium ore leaching neutralization solution, stir for 30 minutes, then add 25% ammonia water to adjust the slurry pH to 7.5-8.0, continue stirring for 30 minutes to obtain a slurry, and let it settle for 8 hours.

[0083] 3rd to 25th precipitation: Repeat the 2nd precipitation process. Analyze the volume change and composition of each precipitation. The volume change curve of the cyclic precipitation is shown in Figure 6 The 5μm, 10μm and 50μm SEM images of α-type beryllium hydroxide obtained from the 10th and 25th precipitations are shown in Figures 7-8 The composition analysis results of α-beryllium hydroxide obtained from the 10th, 15th, 20th and 25th precipitations are shown in Table 3.

[0084] The α-type beryllium hydroxide precipitate obtained by the 25th precipitation was subjected to crystal transformation and post-treatment in the manner described in Example 1 to obtain β-type beryllium hydroxide crystals. The 5 μm SEM images of the obtained β-type beryllium hydroxide and the β-type beryllium hydroxide obtained in Comparative Example 1 are shown in FIG. Fig. 9 .

[0085] Depend on Figure 6 It can be seen that from the third cycle of sedimentation, the solid-liquid separation phenomenon is clearly visible, and from the fifth cycle of sedimentation, the slurry sedimentation volume shows an upward trend, until the volume changes little after the tenth cycle.

[0086] Depend on Figures 7-8 It can be seen that the nucleus of beryllium hydroxide precipitated for the 25th time is larger than that of beryllium hydroxide precipitated for the 10th time. In the final stage of precipitation and crystallization, the system reaches a liquid-solid solubility equilibrium, and the crystal and the solution at the interface reach an equilibrium state, that is, the solubility of the precipitated substance is approximately equal to the concentration of the solution at the crystal interface, and the grains stop growing. During the precipitation process, the solid-liquid equilibrium state of the system is destroyed by stirring at an appropriate temperature, and then it is left to stand to facilitate the growth of crystal particles, that is, the "aging" process. In the same system, the solubility of fine crystals is much greater than the dissolution of coarse crystals. Coarse crystals are in a saturated state in the solution, while tiny crystals are unsaturated, that is, microcrystals dissolve, which increases the concentration of the solution. According to the diffusion effect, the precipitated substance continues to precipitate on the large crystals, and the large crystals grow further. In the next precipitation, the precipitation of the previous suspension is used as a seed, the microcrystals dissolve, the solution concentration is increased, and the coarse crystals continue to grow. This process is repeated continuously, and the fine crystals dissolve while the coarse crystals grow. It can be concluded that the quality of the crystal nuclei produced in the 25th precipitation is much greater than that produced in the 10th precipitation.

[0087] Table 3 Composition analysis of α-type beryllium hydroxide obtained by precipitation

[0088]

[0089] It can be seen from Table 3 that under high temperature boiling conditions and room temperature conditions, BeO and F - The contents of Al2O3 are comparable, with no significant difference. Moreover, the Al2O3 content of circulating precipitation of beryllium ore leaching neutralization solution under normal temperature conditions is lower than that of traditional boiling precipitation.

[0090] Depend on Fig. 9 It can be seen that the beryllium hydroxide precipitate products obtained under the two conditions of room temperature and boiling after the subsequent alkaline washing process have similar morphologies, which are β-type, and both present large particles with uniform distribution.

[0091] In this embodiment, the pH value of the precipitation process is adjusted to 7.5-8.0 by ammonia water at room temperature. The beryllium sulfate in the beryllium ore leaching neutralization solution is precipitated in the form of solid beryllium hydroxide, which can reduce the volume of beryllium hydroxide precipitation. In the early stage of the cycle, as the number of cyclic precipitation increases, the precipitation volume increases and tends to be stable after reaching a certain number of times. The ammonia consumption per precipitation is between 55 and 64 mL, and the ammonia consumption per cubic meter of beryllium ore leaching neutralization solution is 0.11-0.13 m 3 In the prior art, each cubic meter of beryllium ore leaching and neutralization solution consumes about 0.39 to 0.53 m3 of ammonia water. 3 , ammonia is very volatile and consumes a lot of ammonia. In contrast, the ammonia consumption of circulating precipitation of beryllium ore leaching neutralization liquid at room temperature is reduced by about 70%.

[0092] Example 6

[0093] The first precipitation: open the beryllium ore leaching neutralization solution feed valve, put the beryllium ore leaching neutralization solution to a height of 0.6m into the beryllium hydroxide precipitation tank, close the feed valve, start the stirring of the precipitation tank, add 28% ammonia water at room temperature to adjust the slurry pH to 7.5-8.0, continue stirring for 30 minutes to obtain a slurry, and let it settle for 6 hours.

[0094] Second precipitation: drain the supernatant from the slurry obtained from the first precipitation and start stirring. After stirring the slurry for 30 minutes, add beryllium ore leaching neutralization solution at a height of 0.3m, and then add 28% ammonia water to adjust the slurry pH to 7.5-8.0. Stir for 30 minutes, record the amount of ammonia water used, and let it settle for 6 hours.

[0095] The third precipitation: repeat the second precipitation method.

[0096] The fourth precipitation: Repeat the second precipitation method, the difference is that after adding the beryllium ore leaching neutralization solution, stirring is started.

[0097] 5th to 10th precipitation: Repeat the 4th precipitation method, except that the precipitation is allowed to stand for 4 hours.

[0098] The α-type beryllium hydroxide precipitate obtained by the 10th precipitation was subjected to crystal transformation and post-treatment in the manner described in Example 1 to obtain β-type beryllium hydroxide crystals. The XRD patterns of the β-type beryllium hydroxide crystals obtained in Comparative Example 1, Example 5 and Example 6 are shown in FIG. Fig.10 , wherein A corresponds to Comparative Example 1, B corresponds to Example 5, and C corresponds to Example 6. The SEM images of the β-type beryllium hydroxide crystals obtained in Comparative Example 1 and Example 6 are shown in Fig.11 .

[0099] Depend on Fig.10 It can be seen that the characteristic peaks are smooth and clear, without impurity peaks, and the crystal morphology is relatively intact. The characteristic peaks of the three are basically the same. The beryllium hydroxide obtained by room temperature cyclic precipitation and the beryllium hydroxide obtained by the existing process both present the same beryllium hydroxide crystal form after the sodium hydroxide alkaline washing process.

[0100] Depend on Fig.11 It can be seen that both of them form large-particle beryllium hydroxide required for industrial production. The beryllium hydroxide produced by the original traditional boiling precipitation process and the beryllium hydroxide produced by normal temperature circulation precipitation are both converted into β-type beryllium hydroxide after alkali washing.

[0101] This example carried out an expanded test, and the results showed that each cubic meter of beryllium ore leaching and neutralization solution precipitation consumed about 0.1m ammonia water. 3 Compared with the original boiling precipitation process, the ammonia consumption per cubic meter of beryllium ore leaching neutralization liquid precipitation is 0.39-0.53m 3 , the consumption of ammonia water for normal temperature circulating precipitation decreased by more than 70%.

[0102] It can be seen from the above embodiments that the existing beryllium hydroxide production process adds ammonia water for precipitation by boiling, which has a large amount of ammonia water volatilization, high energy consumption, and a bad operating environment. The preparation method of β-type beryllium hydroxide crystals provided by the present invention reduces the harm of ammonia water volatilization to operators, reduces energy consumption and ammonia water consumption.

[0103] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing β-type beryllium hydroxide crystals, characterized in that: The following steps are involved: The first beryllium ore leaching solution and the first ammonia water are first mixed to perform a first precipitation reaction to obtain a first α-type beryllium hydroxide; Repeating the first mixing and first precipitation reaction 2 to 25 times, the raw materials for each mixing and precipitation reaction include beryllium ore leaching solution, ammonia water and α-type beryllium hydroxide obtained in the previous precipitation reaction; The concentration of beryllium oxide in the first beryllium ore leachate and the beryllium ore leachate is independently 15-30 g / L; the ratio of the total volume of the first beryllium ore leachate and the beryllium ore leachate to the total volume of the first ammonia water and the ammonia water is 10-6.7:1; the temperature of the first precipitation reaction is 25-70° C.; The α-type beryllium hydroxide obtained from the last precipitation reaction is mixed with a sodium hydroxide solution and subjected to crystal transformation to obtain the β-type beryllium hydroxide crystal.

2. The preparation method according to claim 1, characterized in that: The pH values ​​of the first beryllium ore leaching solution and the beryllium ore leaching solution are independently 2-6; the concentration of aluminum oxide in the first beryllium ore leaching solution and the beryllium ore leaching solution is independently 0.01-0.2 g / L, and the concentration of fluoride ions is independently 0.1-0.5 g / L.

3. The preparation method according to claim 1, characterized in that: The concentrations of the first aqueous ammonia and the aqueous ammonia are independently 25% to 30%; the pH value of the reaction system obtained by the first mixing is 5 to 9.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The first precipitation reaction time is 0.1 to 2.5 hours.

5. The preparation method according to claim 1, characterized in that: The concentration of the sodium hydroxide solution is 40-100 g / L; the α-type beryllium hydroxide is calculated as beryllium oxide, and the mass ratio of the sodium hydroxide in the sodium hydroxide solution to the α-type beryllium hydroxide obtained by the last precipitation reaction is 0.3-1.3:

1.

6. The preparation method according to claim 1 or 5, characterized in that: The temperature of the crystal transformation is 80-150° C., and the time is 0.5-3 hours.

7. The preparation method according to claim 1, characterized in that: The crystal transformation further includes dilution and heat treatment performed in sequence.

8. The preparation method according to claim 7, characterized in that: The diluting reagent is water; the α-type beryllium hydroxide is calculated as beryllium oxide, and the mass ratio of the water to the α-type beryllium hydroxide obtained in the last precipitation reaction is 23420-47000:

1.

9. The preparation method according to claim 7, characterized in that: The heat treatment temperature is 70-150° C. and the time is 0.1-2 hours.

10. The preparation method according to claim 1, characterized in that: The final precipitation reaction also includes solid-liquid separation; the solid-liquid separation includes suction filtration, filter pressing or centrifugal treatment.

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