Preparation method of sodium tungstate

Abstract

The invention provides a preparation method of sodium tungstate, which comprises the following steps: S1, acidified lepidolite leachate and an activated HP1053 resin column are provided, and the pH value of the acidified lepidolite leachate is adjusted to 3-4 by using sulfuric acid; s2, introducing the acidified lepidolite leachate into an HP1053 resin column at a preset first flow rate, and detecting a sample until an adsorption end point; s3, cleaning the adsorbed HP1053 resin column with pure water; s4, preparing a 10-20wt% NaOH solution, introducing the NaOH solution into the cleaned HP1053 resin column at a preset second flow rate, and replacing WO4 < 2-> in the resin by OH <-> to obtain a desorption solution obtained by desorption, namely a sodium tungstate solution; and S5, evaporating and crystallizing the desorption solution until water is evaporated to dryness, and drying in a drying oven to obtain sodium tungstate.

Description

Technical Field

[0001] This application relates to the field of materials, and particularly to a preparation method of sodium tungstate. Background Art

[0002] Lepidolite, also known as "scale mica", often contains metal elements such as tungsten, rubidium, and cesium. It is mainly found in pegmatites, as well as in greisens and high-temperature hydrothermal veins, and is a mineral raw material for extracting lithium. During the process of extracting lithium, lepidolite needs to be leached. The leaching solution often contains abundant metal elements such as tungsten, rubidium, and cesium. If these metal elements are not separated and extracted, it will often cause pollution and waste. Summary of the Invention

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

[0004] The technical solution of this application is realized as follows: The present invention provides a preparation method of sodium tungstate, including the following steps: S1, providing an acidified lepidolite leaching solution and an activated HP1053 resin column, wherein the acidified lepidolite leaching solution is adjusted to a pH of 3 - 4 with sulfuric acid; S2, introducing the acidified lepidolite leaching solution into the HP1053 resin column at a predetermined first flow rate, detecting and spotting until the adsorption end point; S3, washing the adsorbed HP1053 resin column with pure water; S4, preparing a 10 - 20 wt% NaOH solution and introducing it into the washed HP1053 resin column at a predetermined second flow rate to utilize OH - to replace WO4 in the resin 2- to obtain a desorbed solution, which is the sodium tungstate solution; S5, evaporating and crystallizing the desorbed solution until the water is completely evaporated, and drying it in an oven to obtain sodium tungstate.

[0005] The advantages or beneficial effects in the above technical solution at least include: The preparation method of sodium tungstate provided by the present invention precisely controls the pH value of the acidified lepidolite leaching solution at 3 - 4, creating a suitable acidity environment for the subsequent adsorption process, enabling the HP1053 resin column to efficiently and specifically adsorb tungstate ions (WO4² - ). Desorption is carried out using a NaOH solution with a specific concentration and flow rate, which can fully elute WO4² on the resin column -, a high-purity sodium tungstate solution is obtained. After evaporation crystallization, washing, and drying, the purity of sodium tungstate can reach over 99.5%, meeting the stringent requirements for product purity in high-end application fields. Further, the present invention uses common lepidolite as a raw material, which has a wide source and relatively low cost. At the same time, the recovery rate of tungsten is increased, the preparation cost is further reduced, and the market competitiveness of sodium tungstate is enhanced. Finally, by activating the HP1053 resin column, the present invention can specifically adsorb tungstate ions (WO4² - ), and will not adsorb lithium and other metal elements in lepidolite, thus having no impact on the subsequent further utilization of the lepidolite leaching solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The drawings illustrate exemplary embodiments of the present application in embodiments of the present invention and, together with the description thereof, are used to explain the principles of the present application. These drawings are included to provide a further understanding of the present application and are included in this specification and form a part of this specification.

[0007] Figure 1 is a flowchart of the method for preparing sodium tungstate provided by an embodiment of the present invention.

[0008] Figure 2 is a system architecture diagram for preparing sodium tungstate using a lepidolite leaching solution provided by an embodiment of the present invention.

[0009] Figures 3 - 9 is a liquid flow diagram in different control processes in the system architecture diagram for preparing sodium tungstate using a lepidolite leaching solution provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] Embodiments of the present application will be described in more detail below with reference to the drawings. Although some embodiments of the present application are shown in the 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 set forth 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 only for illustrative purposes and are not used to limit the protection scope of the present application.

[0011] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0012] The names of the messages or information exchanged between multiple devices in the embodiments of the present application are only for illustrative purposes and are not used to limit the scope of these messages or information.

[0013] Referring to Figure 1, an embodiment of the present invention provides a preparation method for preparing sodium tungstate using a leaching solution of lepidolite, comprising the following steps: S1. Provide an acidified leaching solution of lepidolite and an activated HP1053 resin column. Among them, the acidified leaching solution of lepidolite has its pH adjusted to 3 - 4 with sulfuric acid; S2. Pass the acidified leaching solution of lepidolite into the HP1053 resin column at a predetermined first flow rate, and detect and sample until the adsorption end point; S3. Wash the adsorbed HP1053 resin column with pure water; S4. Prepare a 10 - 20wt% NaOH solution and pass it into the washed HP1053 resin column at a predetermined second flow rate to use OH - to replace WO4 in the resin, and the obtained desorption solution obtained by desorption is the sodium tungstate solution; 2- S5. Evaporate and crystallize the desorption solution until the water is completely evaporated, and then place it in an oven to dry to obtain sodium tungstate. S5. Evaporate the desorption solution until the water is completely evaporated, and then place it in an oven to dry to obtain sodium tungstate.

[0014] In step S1, in the actual process, the temperature of the leaching solution of lepidolite is 20 - 40°C, and the tungsten content is about 120 - 180 ml / L.

[0015] The HP1053 resin column is produced by Jiangsu Hap Functional Materials Co., Ltd. and can be obtained through commercial purchase. In order to obtain the best adsorption environment for the HP1053 resin column, the present invention designs the following experiments: Sample preparation: Use sulfuric acid to prepare 7 groups of solutions with pH values of 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 respectively from the leaching solution of lepidolite, and the tungstate ion concentration is about 144 mg / L.

[0016] Adsorption experiment: Pass each group of solutions into the HP1053 resin column in the same activated state respectively, with the flow rate fixed at 4 BV / h, and adsorb until the tungsten content in the effluent is stable. Monitor the pH of the effluent with a pH meter and record the adsorption capacity at the adsorption end point.

[0017] Washing and desorption: Wash the resin column with pure water at a flow rate of 2 - 3 BV / h, and recover the wash liquor. Prepare a 15wt% NaOH solution and pass it into the resin column at a flow rate of 1 BV / h to desorb tungstate ions, collect the desorption solution to measure the tungsten content, and calculate the desorption rate and recovery rate.

[0018] Repeat the experiment: Conduct three parallel experiments for each pH value and take the average. The experimental data are shown in Table 1.

[0019] Data processing Calculation of adsorption rate: Adsorption rate (%) = (total tungsten amount before adsorption - total tungsten amount in the effluent after adsorption) / total tungsten amount before adsorption × 100%.

[0020] Recovery rate calculation: Recovery rate (%) = (total amount of tungsten desorbed) / total amount of tungsten before adsorption × 100%.

[0021] Table 1 shows the adsorption rate and desorption rate data at different pH values

[0022] From the above data, it can be seen that different pH values have a great influence on the adsorption rate. Experiments have proved that by activating the HP1053 resin column, the adsorption capacity of the HP1053 resin column can be greatly increased, and its adsorption capacity can be increased by about 30%. Experiments have proved that when the HP1053 resin column is activated, it has a good specific adsorption effect on tungstate ions, and does not adsorb other ions such as lithium, rubidium, and cesium.

[0023] As a further improvement, the preparation method of the activated HP1053 resin column specifically includes: The HP1053 resin column can be activated with sulfuric acid at a flow rate of 2 BV / h and a concentration of 2%. Measure the pH of the effluent. The pH value of the effluent at the activation end point is 3 - 4. If the pH of the effluent is too low, it can be adjusted back with pure water. Preferably, in one embodiment, the pH value of the effluent at the activation end point is about 3.5.

[0024] The present invention has found through experiments that HP1053 resin is an ion exchange resin with specific functional groups, and the ionization and ion exchange ability of its functional groups are significantly affected by pH. In an environment with a pH of 3.5, the functional groups on the resin can form the most stable complex with tungstate ions in the solution or undergo the most effective ion exchange reaction. When the pH is too low, excessive hydrogen ions will compete with tungstate ions for the active sites on the resin, interfering with the adsorption process of tungstate and reducing the selective adsorption ability of the resin for tungstate; while when the pH is too high, it may cause structural changes or changes in the ionization state of the functional groups on the resin, thereby affecting its adsorption performance for tungstate.

[0025] The acidified leaching solution of lithium mica refers to: the original leaching solution (tungsten-containing feed solution) is adjusted to a pH of 3 - 4 by adding sulfuric acid. Preferably, the pH is adjusted to about 3.5. About 5 ml of concentrated sulfuric acid is consumed for every 5 L of the original leaching solution. Acidifying the original leaching solution is mainly to make its acidic environment the same as that of the activated HP1053 resin column. Otherwise, as the adsorption progresses, the acidic environment of the HP1053 resin column will be destroyed, thereby reducing its adsorption efficiency.

[0026] In step S2, the acidified leaching solution of lepidolite is introduced into the HP1053 resin column at a predetermined first flow rate, which specifically includes: The acidified leaching solution of lepidolite is introduced into the HP1053 resin column at 4 BV / h. It can be understood that by controlling the flow rate of the lepidolite leaching solution, the adsorption capacity of the HP1053 resin column can also be improved to a certain extent. If the flow rate is too small, the overall adsorption efficiency is low, while if the flow rate is too large, the adsorption capacity decreases.

[0027] Furthermore, the adsorption end point can be determined by detecting the tungsten content in the outflowing liquid. Preferably, when the tungsten content in the outflowing liquid is in the range of 30 - 40 ppm, it can be determined that the adsorption end point is reached.

[0028] In step S3, the adsorption - after HP1053 resin column is washed with pure water, which specifically includes: The residual leaching solution of lepidolite in the HP1053 resin column is washed out as much as possible with pure water at a rate of 2 - 3 BV / h. The rate of the pure water should not be too fast, as too fast will cause partial desorption of tungstate ions. As a further improvement, the washing solution can be further returned to step S1 as the solution for acidifying the lepidolite leaching solution, thereby reducing the usage amount of sulfuric acid and the loss rate of the lepidolite leaching solution. Specifically, during the acidification of the lepidolite leaching solution, the washing solution can be first added to the lepidolite leaching solution, and then sulfuric acid is added for secondary acidification.

[0029] In step S4, a 10 - 20 wt% NaOH solution is prepared and introduced into the washed HP1053 resin column at a predetermined second flow rate, which specifically includes: A 10 - 20 wt% NaOH solution is introduced into the washed HP1053 resin column at a flow rate of 1 BV / h.

[0030] In step S5, the desorption liquid is evaporated to crystallization until the water is completely evaporated, and then placed in an oven for drying to obtain sodium tungstate, which specifically includes: The desorption liquid, that is, the mixed solution of sodium tungstate and liquid alkali, is evaporated to crystallization; The crystals are washed once with pure water at 20°C, and the washing solution is returned to the liquid before evaporation to crystallization. Then, they are washed a second time with ethanol at 20°C. After washing, the product is dried to obtain sodium tungstate with a purity of over 99.5% (Note: at 20°C, the solubility of sodium tungstate and sodium hydroxide in water is 72 g and 109 g respectively; the solubility of sodium tungstate and sodium hydroxide in ethanol is 17.3 g and <0.01 g respectively).

[0031] In order to further activate the used HP1053 resin column, it can further include: S6. Clean the used HP1053 resin column with pure water to reduce alkalinity and reduce the amount of sulfuric acid used subsequently. S7. Perform secondary activation with sulfuric acid at a flow rate of 0.5 - 1 BV / h, a concentration of 3%, and a temperature of 40 - 50 °C. After the node ends, let water flow through and measure the pH of the effluent. The pH value of the effluent at the activation end point is 3 - 4.

[0032] Please refer to Figure 2 As shown, the embodiment of the present invention further provides a tungsten adsorption - desorption system, which includes: A feed pipeline 30, which is respectively connected to a sulfuric acid feed pipe 10, a pure water feed pipe 11, a sodium hydroxide feed pipe 12, and a lepidolite leaching solution feed pipe 100. The bottom of the first HP1053 resin column 15 is connected to the feed pipe 30 through a first pipeline 31, and a first solenoid valve 13 is arranged on the first pipeline 31. The bottom of the first HP1053 resin column 15 further includes a first waste discharge pipeline 20. The bottom of the second HP1053 resin column 16 is connected to the feed pipe 30 through a second pipeline 32, and a second solenoid valve 14 is arranged on the second pipeline 32. The bottom of the second HP1053 resin column 16 further includes a second waste discharge pipeline 21. The top of the first HP1053 resin column 15 is connected to the top of the second HP1053 resin column 16 through a third pipeline 33, and a third solenoid valve 17 and a fourth solenoid valve 18 are arranged on the third pipeline 33. A discharge pipeline 34 is connected to the third pipeline 33 between the third solenoid valve 17 and the fourth solenoid valve 18, and a fifth solenoid valve 19 is arranged on it.

[0033] Please refer to Figure 3 As shown, the activation of the first HP1053 resin column 15 and the second HP1053 resin column 16 includes the following steps: 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 discharge pipeline 21. Perform activation with sulfuric acid at a flow rate of 2 BV / h and a concentration of 2%. Measure the pH of the effluent. The pH value of the effluent at the activation end point is 3 - 4. If the pH of the effluent is too small, the pure water feed pipe 11 can be opened to adjust it back with pure water.

[0034] Please refer to Figure 4 As shown, after the activation of the first HP1053 resin column 15 and the second HP1053 resin column 16, start the adsorption work, including the following steps: Open the lithium mica leaching solution feed pipe 100, the first solenoid valve 13, the third solenoid valve 17, the fourth solenoid valve 18, and the second waste discharge pipe 21; Feed the acidified lithium mica leaching solution into the first HP1053 resin column 15 at a rate of 4 BV / h. When the tungsten content in the liquid flowing out from the top of the first HP1053 resin column 15 is greater than 30 - 40 ppm, it can be determined that the adsorption end point is reached. At this time, the effluent flowing out from the second HP1053 resin column 16 can enter the recovery steps of other metals, which will not be elaborated here. In one embodiment, the tungsten content in the acidified lithium mica leaching solution is 144 mg / L.

[0035] Table 2 shows the test results of the spotted tungsten content (mg / L) in different resin columns during the adsorption process

[0036] It can be seen from Table 2 that when the adsorption volume is 950 - 1000 BV, the tungsten content in the effluent of the first HP1053 resin column ≤ 1 mg / L, while when the adsorption volume is 1660 BV, the tungsten content in the effluent of the first HP1053 resin column is 36.618 mg / L, and the tungsten content in the effluent of the second HP1053 resin column is 0.0959 mg / L (at this time, the first HP1053 resin column has not been penetrated and still has a certain adsorption capacity). Due to the shortage of the original solution, the adsorption was stopped and pure water quick washing (pre-desorption water washing) was carried out. In addition, through testing, the concentrations of lithium ions, rubidium ions, and cesium ions in the effluent of the first HP1053 resin column and the second HP1053 resin column are basically the same as those in the raw water. Thus, it can be seen that the activated HP1053 resin has specific adsorption for tungstate ions (WO4² - )

[0037] Please refer to Figure 5 As shown, after the adsorption work is completed, it is necessary to clean the remaining lithium mica leaching solution in the first HP1053 resin column 15, including the following steps: Open the pure water feed pipe 11, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19; Wash out the remaining lithium mica leaching solution in the first HP1053 resin column 15 with pure water at a rate of 2 - 3 BV / h as much as possible.

[0038] Please refer to Figure 6 As shown, after the cleaning is completed, it is necessary to elute the tungsten in the first HP1053 resin column 15, including the following steps: Open the sodium hydroxide feed pipe 12, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19; A NaOH solution with a concentration of 10 - 20 wt% is introduced into the cleaned first HP1053 resin column 15 at a flow rate of 1 BV / h for the elution of tungsten. During the elution process, the desorbed liquid is sodium tungstate solution, which is collected from the pipeline corresponding to the fifth solenoid valve 19. Finally, the desorbed liquid is evaporated to crystallization until the water is completely evaporated, and then placed in an oven to dry to obtain sodium tungstate.

[0039] Table 3 is the data table for tungsten adsorption and recovery

[0040] The results in Table 3 show that: the adsorption rate is 99.33%, the desorption rate of the first HP1053 resin column is 99.268%, and the recovery rate of tungsten is 98.61% (since the second HP1053 resin column has always been below 1 PPM, even below 0.05 PPM, the recovery rate is much greater than 98.61%). The total desorption amount of the first HP1053 resin column and the second HP1053 resin column is 261.3414 g > the total tungsten amount of 244.8 g. Although there is a certain error due to the excessive dilution factor in the chemical analysis, it can still show that even when the adsorption volume is increased to 1660 BV, using 2 - 3 BV - 15% NaOH can still elute all the tungsten.

[0041] Please refer to Figures 7 - 8 As shown, after the desorption is completed, in order to activate the first HP1053 resin column 15, it may further include: Open the pure water inlet pipe 11, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19; Wash out the residual sodium hydroxide solution in the first HP1053 resin column 15 with pure water at a rate of 2 - 3 BV / h as much as possible; Open the sulfuric acid inlet pipe 10, the first solenoid valve 13, the third solenoid valve 17, and the fifth solenoid valve 19; Use sulfuric acid with a flow rate of 0.5 - 1 BV / h, a concentration of 3%, and a temperature of 40 - 50 °C to perform secondary activation on the first HP1053 resin column 15. After the node ends the water supply, measure the pH of the outlet water. The pH value of the outlet water at the activation end is 3 - 4.

[0042] Please refer to Figure 9 As shown, during the secondary use process, since the second HP1053 resin column 16 has adsorbed a certain amount of tungsten during the first adsorption process, therefore, during the secondary use process, in order to recover as much as possible from the second HP1053 resin column 16, preferably, the adsorption process first enters from the second HP1053 resin column 16 and then exits from the first HP1053 resin column 15 (i.e., in the opposite direction to the first adsorption). The specific steps are as follows: Open the lepidolite leaching solution feed pipe 100, the second solenoid valve 14, the fourth solenoid valve 18, the third solenoid valve 17, and the first waste discharge pipe 20; Feed the acidified lepidolite leaching solution into the second HP1053 resin column 16 at a rate of 4 BV / h. When the tungsten content in the liquid flowing out from the top of the second HP1053 resin column 16 is greater than 30 - 40 ppm, it can be determined that the adsorption end point is reached. At this time, the effluent flowing out from the first HP1053 resin column 15 can enter the recovery steps of other metals, which will not be elaborated here.

[0043] Those skilled in the art should understand that the above embodiments are only for clearly illustrating the present application, rather than limiting the scope of the present application. For those skilled in the art, other changes or variations can be made based on the above disclosure, and these changes or variations are still within the scope of the present application.

Claims

1. A preparation method of sodium tungstate, wherein the preparation method is based on a leaching solution of lepidolite to prepare sodium tungstate, and is characterized in that: It includes the following steps: S1. Provide an acidified leaching solution of lepidolite and an activated HP1053 resin column. Among them, the acidified leaching solution of lepidolite has its pH adjusted to 3 - 4 with sulfuric acid; S2. Pass the acidified leaching solution of lepidolite into the HP1053 resin column at a predetermined first flow rate, and perform spotting detection until the adsorption end point; S3. Wash the adsorbed HP1053 resin column with pure water; S4. Prepare a 10 - 20 wt% NaOH solution and introduce it into the cleaned HP1053 resin column at a predetermined second flow rate to utilize OH - to replace WO4 in the resin 2- and obtain the desorbed solution, which is the sodium tungstate solution; S5. Evaporate and crystallize the desorption solution until the water is completely evaporated, and then place it in an oven to dry to obtain sodium tungstate.

2. The preparation method of sodium tungstate according to claim 1, characterized in that: The preparation method of the activated HP1053 resin column specifically includes: The HP1053 resin column is activated with sulfuric acid at a flow rate of 2 BV / h and a concentration of 2%. Measure the pH of the effluent water. The pH value of the effluent water at the activation end point is 3 - 4. If the pH of the effluent water is too low, adjust it back with pure water.

3. The preparation method of sodium tungstate according to claim 1, characterized in that: In step S2, the step of passing the acidified leaching solution of lepidolite into the HP1053 resin column at a predetermined first flow rate specifically includes: Pass the acidified leaching solution of lepidolite into the HP1053 resin column at a flow rate of 4 BV / h. When the tungsten content in the outflowing liquid is within the range of 30 - 40 ppm, it is determined that the adsorption end point is reached.

4. The preparation method of sodium tungstate according to claim 1, characterized in that: In step S3, the step of washing the adsorbed HP1053 resin column with pure water specifically includes: Wash out the residual leaching solution of lepidolite in the HP1053 resin column with pure water at a rate of 2 - 3 BV / h.

5. The preparation method of sodium tungstate according to claim 1, characterized in that: In step S4, the step of preparing a 10 - 20 wt% NaOH solution and passing it into the washed HP1053 resin column at a predetermined second flow rate specifically includes: Prepare a 10 - 20 wt% NaOH solution and pass it into the washed HP1053 resin column at a flow rate of 1 BV / h.

6. The preparation method of sodium tungstate according to claim 1, characterized in that: In step S5, the step of evaporating and crystallizing the desorption solution until the water is completely evaporated, and then placing it in an oven to dry to obtain sodium tungstate specifically includes: Perform evaporation crystallization on the desorption solution; Wash the crystal once with pure water at 20°C, return the washing solution to the solution before evaporation crystallization, then wash it a second time with ethanol at 20°C, and dry the washed product to obtain sodium tungstate with a purity of over 99.5%.

7. The preparation method of sodium tungstate according to claim 1, characterized in that: The preparation method further includes: S6. Wash the used HP1053 resin column with pure water to reduce alkalinity and reduce the subsequent consumption of sulfuric acid; S7. Perform secondary activation with sulfuric acid at a flow rate of 0.5 - 1 BV / h, a concentration of 3%, and a temperature of 40 - 50°C. Stop water flow at the node, measure the pH of the effluent water, and the pH value of the effluent water at the activation end point is 3 - 4.

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