A preparation method of sodium tungstate

Abstract

The present application provides a method for preparing sodium tungstate, comprising the following steps: S1, providing an acidified lepidolite leachate and an activated HP1053 resin column, wherein the acidified lepidolite leachate is adjusted to a pH of 3 to 4 using sulfuric acid; S2, passing the acidified lepidolite leachate into the HP1053 resin column at a predetermined first flow rate, detecting a sample until the adsorption end point; S3, washing the HP1053 resin column after adsorption with pure water; S4, preparing a 10-20 wt% NaOH solution and passing it into the washed HP1053 resin column at a predetermined second flow rate to utilize OH to activate the sodium tungstate; ‑ WO4 in the resin 2‑ Replace, and obtain the desorption liquid obtained by desorption, which is sodium tungstate solution; S5, evaporate and crystallize the desorption liquid until the water is evaporated to dryness, and put it into an oven for drying to obtain sodium tungstate.

Description

Technical Field

[0001] The present application relates to the field of materials, and in particular to a method for preparing sodium tungstate. Background Art

[0002] Lepidolite, also known as "lepidolite," often contains metallic elements such as tungsten, rubidium, and cesium. Found primarily in pegmatites, but also in greisen and high-temperature hydrothermal veins, it is a mineral raw material for lithium extraction. During lithium extraction, lepidolite must be leached. The leachate often contains abundant metallic elements such as tungsten, rubidium, and cesium. Failure to separate and extract these metallic elements can lead to pollution and waste. Summary of the Invention

[0003] The object of the present invention is to solve the above problems and provide a method for preparing sodium tungstate.

[0004] The technical solution of this application is achieved as follows:

[0005] The present invention provides a method for preparing sodium tungstate, comprising the following steps:

[0006] S1, providing an acidified lepidolite leachate and an activated HP1053 resin column, wherein the acidified lepidolite leachate is adjusted to a pH of 3 to 4 using sulfuric acid;

[0007] S2, passing the acidified lepidolite leachate into the HP1053 resin column at a predetermined first flow rate, and detecting the sample until the adsorption endpoint;

[0008] S3, washing the adsorbed HP1053 resin column with pure water;

[0009] S4, prepare 10~20wt% NaOH solution and pass it into the cleaned HP1053 resin column at a predetermined second flow rate to utilize OH - WO4 in the resin 2- Replace, and the desorption liquid obtained by desorption is sodium tungstate solution;

[0010] S5, evaporating and crystallizing the desorbed liquid until the water is evaporated to dryness, and drying in an oven to obtain sodium tungstate.

[0011] The advantages or beneficial effects of the above technical solution include at least:

[0012] The preparation method of sodium tungstate provided by the present invention precisely controls the pH value of the acidified lepidolite leachate to be between 3 and 4, thereby creating a suitable acidic environment for the subsequent adsorption process, so that the HP1053 resin column can efficiently and specifically adsorb tungstate ions (WO4² - ). Using NaOH solution with a specific concentration and flow rate for desorption can fully elute WO4² on the resin column.- , obtaining a high-purity sodium tungstate solution. After evaporation, crystallization, washing, and drying, the purity of sodium tungstate can reach over 99.5%, meeting the stringent purity requirements of high-end applications. Furthermore, the present invention uses common lepidolite as a raw material, which is widely available and relatively low in cost. It also improves the recovery rate of tungsten, further reduces the preparation cost, and enhances the market competitiveness of sodium tungstate. Finally, the present invention activates the HP1053 resin column to - ) produces specific adsorption, but will not adsorb lithium and other metal elements in the lepidolite, thus will not affect the subsequent further utilization of the lepidolite leachate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings illustrate exemplary implementations of the present application of embodiments of the present invention and, together with the description, are used to explain the principles of the present application. These drawings are included to provide a further understanding of the present application, and the drawings are included in and constitute a part of this specification.

[0014] Figure 1 The present invention provides a flow chart of a method for preparing sodium tungstate.

[0015] Figure 2 This is a system architecture diagram for preparing sodium tungstate using lepidolite leachate provided in an embodiment of the present invention.

[0016] Figure 3-9 This is a diagram of the liquid flow in different control processes in the system architecture diagram for preparing sodium tungstate using lepidolite leachate provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following describes embodiments of the present application in more detail with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are for illustrative purposes only and are not intended to limit the scope of protection of the present application.

[0018] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] The names of the messages or information exchanged between multiple devices in the embodiments of the present application are only used for illustrative purposes and are not used to limit the scope of these messages or information.

[0020] Reference Figure 1The embodiment of the present invention provides a method for preparing sodium tungstate using a lepidolite leachate, comprising the following steps:

[0021] S1, providing an acidified lepidolite leachate and an activated HP1053 resin column, wherein the acidified lepidolite leachate is adjusted to a pH of 3 to 4 using sulfuric acid;

[0022] S2, passing the acidified lepidolite leachate into the HP1053 resin column at a predetermined first flow rate, and detecting the sample until the adsorption endpoint;

[0023] S3, washing the adsorbed HP1053 resin column with pure water;

[0024] S4, prepare 10~20wt% NaOH solution and pass it into the cleaned HP1053 resin column at a predetermined second flow rate to utilize OH - WO4 in the resin 2- Replace, and the desorption liquid obtained by desorption is sodium tungstate solution;

[0025] S5, evaporating and crystallizing the desorbed liquid until the water is evaporated to dryness, and drying in an oven to obtain sodium tungstate.

[0026] In step S1, in the actual process, the temperature of the lepidolite leachate is 20-40°C and contains about 120-180 ml / L of tungsten.

[0027] The HP1053 resin column is produced by Jiangsu Haipu Functional Materials Co., Ltd. and can be purchased commercially. In order to obtain the optimal adsorption environment of the HP1053 resin column, the present invention designed the following experiment:

[0028] Sample preparation: The lepidolite leachate was prepared with sulfuric acid into seven groups of solutions with pH values of 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0, respectively. The tungstate concentration of each solution was approximately 144 mg / L.

[0029] Adsorption experiment: Each solution was passed through an HP1053 resin column in the same activation state at a fixed flow rate of 4 BV / h. Adsorption was continued until the tungsten content in the effluent stabilized. The effluent pH was monitored with a pH meter, and the adsorption capacity at the adsorption endpoint was recorded.

[0030] Washing and Desorption: Wash the resin column with pure water at a flow rate of 2-3 BV / h, and recover the eluate. Prepare a 15wt% NaOH solution and pass it through the resin column at a flow rate of 1 BV / h to desorb tungstate. Collect the desorbed liquid, measure the tungsten content, and calculate the desorption rate and recovery rate.

[0031] Repeat the experiment: Three parallel experiments were performed for each pH value, and the average value was taken. The experimental data are shown in Table 1.

[0032] Data processing

[0033] Calculation of adsorption rate: Adsorption rate (%) = (total amount of tungsten before adsorption - total amount of tungsten in effluent after adsorption) / total amount of tungsten before adsorption × 100%.

[0034] Recovery rate calculation: Recovery rate (%) = (total amount of tungsten obtained by desorption) / total amount of tungsten before adsorption × 100%.

[0035] Table 1 shows the adsorption and desorption rates at different pH values.

[0036]

[0037] The above data demonstrates that different pH levels significantly influence adsorption rates. Experiments have demonstrated that activation of the HP1053 resin column significantly increases its adsorption capacity, increasing it by approximately 30%. Experiments have also demonstrated that activated HP1053 resin exhibits excellent specific adsorption for tungstate, while not adsorbing other ions, such as lithium, rubidium, and cesium.

[0038] As a further improvement, the preparation method of the activated HP1053 resin column specifically comprises:

[0039] The HP1053 resin column can be activated using 2% sulfuric acid at a flow rate of 2 BV / h. The pH of the effluent water is measured. The pH of the effluent water at the end of activation is 3-4. If the pH of the effluent water is too low, it can be adjusted with pure water. Preferably, in one embodiment, the pH of the effluent water at the end of activation is approximately 3.5.

[0040] Through experiments, the present inventors discovered that HP1053 resin is an ion exchange resin with specific functional groups whose ionization and ion exchange capacity are significantly affected by pH. At a pH of 3.5, the functional groups on the resin form the most stable complexes or undergo the most efficient ion exchange reactions with tungstate ions in solution. When the pH is too low, excess hydrogen ions compete with tungstate ions for active sites on the resin, interfering with the adsorption process and reducing the resin's selective adsorption capacity for tungstate. When the pH is too high, the functional groups on the resin may undergo structural changes or alter their ionization states, thereby affecting its adsorption performance for tungstate.

[0041] Acidified lepidolite leachate refers to the process where the pH of the leaching solution (tungsten-containing solution) is adjusted to a range of 3-4, preferably around 3.5, by adding sulfuric acid. Approximately 5 ml of concentrated sulfuric acid is used for every 5 liters of leaching solution. Acidification of the leaching solution is primarily to ensure that the acidic environment of the activated HP1053 resin column is the same as the environment in which the activated HP1053 resin column is exposed. Otherwise, the acidic environment of the HP1053 resin column will be destroyed as adsorption progresses, reducing adsorption efficiency.

[0042] In step S2, the acidified lepidolite leachate is passed into the HP1053 resin column at a predetermined first flow rate, specifically comprising:

[0043] The acidified lepidolite leachate was passed through the HP1053 resin column at 4 BV / h. It is understood that by controlling the flow rate of the lepidolite leachate, the adsorption capacity of the HP1053 resin column can also be increased to a certain extent. Too low a flow rate results in low overall adsorption efficiency, while too high a flow rate reduces adsorption capacity.

[0044] Furthermore, the adsorption endpoint can be determined by detecting the tungsten content in the outflowing liquid. Preferably, when the tungsten content in the outflowing liquid is within the range of 30-40 ppm, it can be determined that the adsorption endpoint has been reached.

[0045] In step S3, the HP1053 resin column after adsorption is cleaned with pure water, specifically comprising:

[0046] The residual lepidolite leachate in the HP1053 resin column is washed out as much as possible with pure water at a rate of 2 to 3 BV / h. The rate of the pure water should not be too fast, as this will cause some tungstate to desorb. As a further improvement, the eluate can be further returned to step S1 as a solution for acidifying the lepidolite leachate, thereby reducing the amount of sulfuric acid used and the loss rate of the lepidolite leachate. Specifically, during the acidification of the lepidolite leachate, the eluate can be first added to the lepidolite leachate, and then sulfuric acid is added for secondary acidification.

[0047] In step S4, the preparation of a 10-20 wt% NaOH solution at a predetermined second flow rate is passed into the cleaned HP1053 resin column, specifically comprising:

[0048] Prepare a 10~20wt% NaOH solution and pass it into the cleaned HP1053 resin column at a flow rate of 1BV / h.

[0049] In step S5, the desorption liquid is evaporated and crystallized until the water is evaporated to dryness, and then placed in an oven for drying to obtain sodium tungstate, which specifically includes:

[0050] The desorption liquid, i.e., a mixture of sodium tungstate and liquid alkali, is evaporated and crystallized;

[0051] The crystals were washed with pure water at 20°C, the washing liquid was returned to the liquid before evaporation and crystallization, and then washed with ethanol for a second time at 20°C. After washing, the product was dried to obtain sodium tungstate with a purity of more than 99.5% (Note: at 20°C, the solubility of sodium tungstate and sodium hydroxide in water is 72g and 109g respectively; the solubility of sodium tungstate and sodium hydroxide in ethanol is 17.3g and <0.01g respectively).

[0052] In order to further activate the HP1053 resin column after use, the following steps may be further performed:

[0053] S6, using pure water to wash the used HP1053 resin column to reduce alkalinity and reduce the subsequent use of sulfuric acid;

[0054] S7, use sulfuric acid with a flow rate of 0.5~1BV / h, a concentration of 3%, and a temperature of 40~50℃ for secondary activation. Water flow ends at the node and the pH of the effluent is measured. The pH value of the effluent at the activation end point is 3~4.

[0055] See Figure 2 As shown, an embodiment of the present invention further provides a tungsten adsorption-desorption system, the system comprising:

[0056] A feed pipe 30, which is connected to a sulfuric acid feed pipe 10, a pure water feed pipe 11, a sodium hydroxide feed pipe 12, and a lepidolite leachate feed pipe 100;

[0057] The bottom of the first HP1053 resin column 15 is connected to the feed pipe 30 through a first pipe 31, and a first solenoid valve 13 is provided on the first pipe 31. The bottom of the first HP1053 resin column 15 further includes a first waste pipe 20;

[0058] The bottom of the second HP1053 resin column 16 is connected to the feed pipe 30 through a second pipe 32, and the second pipe 32 is provided with a second solenoid valve 14. The bottom of the second HP1053 resin column 16 further includes a second waste pipe 21, and the top of the first HP1053 resin column 15 is connected to the top of the second HP1053 resin column 16 through a third pipe 33, and the third solenoid valve 17 and the fourth solenoid valve 18 are provided on the third pipe 33;

[0059] The discharge pipe 34 is connected to the third pipe 33 between the third solenoid valve 17 and the fourth solenoid valve 18 , and the fifth solenoid valve 19 is installed on the discharge pipe 34 .

[0060] See Figure 3As shown, the activation of the first HP1053 resin column 15 and the second HP1053 resin column 16 includes the following steps:

[0061] Open the sulfuric acid feed pipe 10, the first solenoid valve 13, the third solenoid valve 17, the fourth solenoid valve 18 and the second waste pipe 21;

[0062] Activation was performed using sulfuric acid at a flow rate of 2BV / h and a concentration of 2%. The pH of the effluent was measured. The pH of the effluent at the activation end point was 3-4. If the pH of the effluent was too low, the pure water feed pipe 11 could be opened to adjust the pH with pure water.

[0063] See Figure 4 As shown, after the first HP1053 resin column 15 and the second HP1053 resin column 16 are activated, the adsorption process begins, including the following steps:

[0064] Open the lepidolite leachate feed pipe 100, the first solenoid valve 13, the third solenoid valve 17, the fourth solenoid valve 18, and the second waste pipe 21;

[0065] The acidified lepidolite leachate is passed through the first HP1053 resin column 15 at a rate of 4 BV / h. When the tungsten content of the liquid flowing out of the top of the first HP1053 resin column 15 exceeds 30-40 ppm, the adsorption endpoint is determined. At this point, the effluent from the second HP1053 resin column 16 can be processed for other metal recovery steps, which will not be further described here. In one embodiment, the tungsten content of the acidified lepidolite leachate is 144 mg / L.

[0066] Table 2 shows the test results of tungsten content of different resin columns during adsorption (mg / L)

[0067]

[0068] As shown in Table 2, when the adsorption volume was between 950 and 1000 BV, the tungsten content in the effluent from the first HP1053 resin column was ≤1 mg / L. At 1660 BV, the tungsten content in the effluent from the first HP1053 resin column was 36.618 mg / L, while the tungsten content in the effluent from the second HP1053 resin column was 0.0959 mg / L (at this time, the first HP1053 resin column had not yet penetrated and still had a certain adsorption capacity). Due to insufficient stock solution, adsorption was stopped and a quick pure water wash (water wash before desorption) was performed. In addition, after testing, the concentrations of lithium ions, rubidium ions, and cesium ions in the effluents from the first and second HP1053 resin columns remained essentially unchanged from those in the raw water. This shows that the activated HP1053 resin has a strong affinity for tungstate ions (WO4² - ) will produce specific adsorption.

[0069] See Figure 5 As shown, the adsorption work is completed, and the remaining lepidolite leachate in the first HP1053 resin column 15 needs to be cleaned, including the following steps:

[0070] Open the pure water feed pipe 11, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19;

[0071] The residual lepidolite leachate in the first HP1053 resin column 15 is washed out as much as possible with pure water at a rate of 2-3 BV / h.

[0072] See Figure 6 As shown, after cleaning is completed, tungsten in the first HP1053 resin column 15 needs to be eluted, including the following steps:

[0073] Open the sodium hydroxide feed pipe 12, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19;

[0074] A 10-20 wt% NaOH solution was passed through the cleaned first HP1053 resin column 15 at a flow rate of 1 BV / h to elute tungsten. The desorbed liquid, a sodium tungstate solution, was collected from the pipeline corresponding to the fifth solenoid valve 19. Finally, the desorbed liquid was evaporated and crystallized until the water was completely evaporated, and then dried in an oven to obtain sodium tungstate.

[0075] Table 3 is the adsorbed tungsten recovery data table

[0076]

[0077] The results in Table 3 show an adsorption efficiency of 99.33%, a desorption efficiency of 99.268% for the first HP1053 resin column, and a tungsten recovery of 98.61%. (Since the second HP1053 resin column consistently maintained below 1 PPM, even below 0.05 PPM, the recovery was significantly greater than 98.61%.) The total desorption volume of 261.3414 g from the first and second HP1053 resin columns exceeded the tungsten total of 244.8 g. This error is due to the large dilution factor used in the assay. However, it also demonstrates that even with an increased adsorption volume of 1660 BV, complete elution is still possible using 2-3 BV of 15% NaOH.

[0078] See Figure 7-8 As shown, after the desorption is completed, in order to activate the first HP1053 resin column 15, the following steps may be further included:

[0079] Open the pure water feed pipe 11, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19;

[0080] Wash out as much of the residual sodium hydroxide solution in the first HP1053 resin column 15 as possible with pure water at a rate of 2-3 BV / h;

[0081] Open the sulfuric acid feed pipe 10, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19;

[0082] The first HP1053 resin column 15 was secondary activated with sulfuric acid at a flow rate of 0.5-1 BV / h, a concentration of 3%, and a temperature of 40-50°C. Water flow was terminated at the node, and the pH of the effluent was measured. The pH value of the effluent at the activation endpoint was 3-4.

[0083] See Figure 9 As shown, during the secondary use, since the second HP1053 resin column 16 has already adsorbed a certain amount of tungsten during the primary adsorption process, in order to recover as much tungsten as possible from the second HP1053 resin column 16 during the secondary use, preferably, the adsorption process first enters from the second HP1053 resin column 16 and then discharges from the first HP1053 resin column 15 (i.e., in the opposite direction of the primary adsorption), which specifically includes the following steps:

[0084] Open the lepidolite leachate feed pipe 100, the second solenoid valve 14, the fourth solenoid valve 18, the third solenoid valve 17, and the first waste pipe 20;

[0085] The acidified lepidolite leachate was passed through the second HP1053 resin column 16 at a rate of 4 BV / h. When the tungsten content of the liquid flowing out of the top of the second HP1053 resin column 16 exceeded 30-40 ppm, the adsorption endpoint was determined. At this point, the effluent from the first HP1053 resin column 15 could be used for other metal recovery steps, which will not be discussed here.

[0086] Those skilled in the art will appreciate that the above embodiments are merely for the purpose of illustrating the present application and are not intended to limit the scope of the present application. Those skilled in the art may make other changes or modifications based on the above disclosure, and such changes or modifications are still within the scope of the present application.

Claims

1. A method for preparing sodium tungstate, wherein the method is based on preparing sodium tungstate from lepidolite leachate, and is characterized by: The preparation method is implemented based on a tungsten adsorption-desorption system, which includes: a feed pipe, which is respectively connected to a sulfuric acid feed pipe, a pure water feed pipe, a sodium hydroxide feed pipe, and a lepidolite leachate feed pipe; the bottom of a first HP1053 resin column is connected to the feed pipe through a first pipe, and a first solenoid valve is provided on the first pipe, and the bottom of the first HP1053 resin column further includes a first waste discharge pipe; the bottom of a second HP1053 resin column is connected to the feed pipe through a second pipe, and a second solenoid valve is provided on the second pipe, and the bottom of the second HP1053 resin column further includes a second waste discharge pipe, and the top of the first HP1053 resin column is connected to the top of the second HP1053 resin column through a third pipe, and a third solenoid valve and a fourth solenoid valve are provided on the third pipe; a discharge pipe is connected to the third pipe between the third solenoid valve and the fourth solenoid valve, and a fifth solenoid valve is provided on the third pipe; The preparation method comprises the following steps: S1, providing an acidified lepidolite leachate and an activated HP1053 resin column, wherein the lepidolite leachate has a tungstate concentration of 144 mg / L, the acidified lepidolite leachate is adjusted to a pH of 3.5 with sulfuric acid, the HP1053 resin column is activated with 2% sulfuric acid at a flow rate of 2 BV / h, the effluent pH is measured, and the effluent pH at the activation endpoint is 3.

5. If the effluent pH is too low, pure water is added to adjust the pH. After activation, the HP1053 resin column has good specific adsorption for tungstate, but does not adsorb lithium, rubidium, and cesium ions; S2, the acidified lepidolite leachate is passed into the HP1053 resin column at a predetermined first flow rate, and the sample is detected to increase the adsorption volume to 1660BV until the adsorption end point. In step S2, the acidified lepidolite leachate is passed into the HP1053 resin column at a predetermined first flow rate, specifically comprising: The acidified lepidolite leachate was passed through the HP1053 resin column at 4 BV / h. When the tungsten content in the effluent liquid was within the range of 30-40 ppm, the adsorption endpoint was determined. S3, washing the adsorbed HP1053 resin column with pure water; S4, prepare 2~3BV, 15% NaOH solution and pass it into the cleaned HP1053 resin column at a flow rate of 1BV / h to utilize OH - WO4 in the resin 2- Replace, and the desorption liquid obtained by desorption is sodium tungstate solution; S5, evaporating and crystallizing the desorbed liquid until the water is evaporated to dryness, and drying in an oven to obtain sodium tungstate.

2. The method for preparing sodium tungstate according to claim 1, wherein: In step S3, the HP1053 resin column after adsorption is cleaned with pure water, specifically comprising: The residual lepidolite leachate in the HP1053 resin column was washed out with pure water at a rate of 2~3BV / h.

3. The method for preparing sodium tungstate according to claim 1, wherein: In step S5, the desorption liquid is evaporated and crystallized until the water is evaporated to dryness, and then placed in an oven for drying to obtain sodium tungstate, which specifically includes: The desorption liquid is evaporated and crystallized; The crystals are washed with pure water at 20°C, the washing liquid is returned to the liquid before evaporation and crystallization, and then washed with ethanol for the second time at 20°C. After washing, the product is dried to obtain sodium tungstate with a purity of more than 99.5%.

4. The method for preparing sodium tungstate according to claim 1, wherein: The preparation method further comprises: S6, using pure water to wash the used HP1053 resin column to reduce alkalinity and reduce the subsequent use of sulfuric acid; S7, use sulfuric acid with a flow rate of 0.5~1BV / h, a concentration of 3%, and a temperature of 40~50℃ for secondary activation. Water flow ends at the node and the pH of the effluent is measured. The pH value of the effluent at the activation end point is 3~4.

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