Method for removing calcium and magnesium ions in zinc sulfate solution and prolonging working time of evaporator

Abstract

The invention discloses a method for removing calcium and magnesium ions in a zinc sulfate solution and prolonging the working time of an evaporator. The method comprises the following steps: mixing and reacting a zinc sulfate solution, zinc fluoride and an alkaline zinc-containing substance, and filtering to obtain the zinc sulfate solution. According to the method provided by the invention, the content of calcium ions and magnesium ions in the zinc sulfate solution can be effectively reduced, other cation impurities are not introduced, the content of fluorine ions in the zinc sulfate solution can be controlled, and corrosion of the fluorine ions to a pipeline is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgy, and particularly relates to a method for removing calcium and magnesium ions in zinc sulfate solution to prolong the working time of an evaporator. BACKGROUND

[0002] When copper smelting dust is treated by a wet method, calcium and magnesium elements in the dust enter the solution during leaching, and the calcium and magnesium ions in the zinc sulfate solution are adjusted in pH value by adding lime in a subsequent impurity removal process. When the calcium and magnesium ions in the zinc sulfate solution enter an evaporator for evaporation, a large amount of scale is formed on the inner wall of the evaporator tube, reducing the thermal efficiency and working time and increasing the cleaning frequency of the inner wall of the evaporator tube.

[0003] Currently, fluorine salts are usually used to remove calcium and magnesium ions in the zinc sulfate solution, but the content of fluorine ions in the zinc sulfate solution is too high due to the influence of cations and fluorine ions in the fluorine salts, which can corrode the pipeline and also introduce other cation impurities and the like. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a method for removing calcium and magnesium ions in zinc sulfate solution to prolong the working time of an evaporator. The method provided in the present application can effectively reduce the content of calcium and magnesium ions in the zinc sulfate solution without introducing other cation impurities, and can also control the content of fluorine ions in the zinc sulfate solution to avoid corrosion of the fluorine ions to the pipeline.

[0005] The present application provides a method for removing calcium and magnesium ions in zinc sulfate solution to prolong the working time of an evaporator. According to an embodiment of the present application, the method comprises: mixing and reacting zinc sulfate solution, zinc fluoride and an alkaline zinc-containing substance, and filtering to obtain zinc sulfate solution.

[0006] According to the method of the above embodiment of the present application, the zinc sulfate solution containing calcium and magnesium ions, zinc fluoride and the alkaline zinc-containing substance are mixed. The zinc fluoride will dissociate fluorine ions (F - ) in the zinc sulfate solution. The fluorine ions can react with calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ) in the zinc sulfate solution to generate insoluble fluoride precipitates (calcium fluoride (CaF2) and magnesium fluoride (MgF2) and the like), and the zinc ions (Zn 2+ ) in the alkaline zinc-containing substance will react with hydroxyl ions (OH -)binding, hydrolysis reaction occurs to generate zinc hydroxide precipitation, the zinc hydroxide precipitation has a large surface area and adsorption capacity, can adsorb and entrain the fluoride ions in the solution, can reduce the concentration of fluoride ions in the zinc sulfate solution, can stably maintain the mass concentration of fluoride ions in the zinc sulfate solution below 100 mg / L, avoids the corrosion of the pipeline by fluoride ions, further through the filtration operation, the generated fluoride precipitate and zinc hydroxide precipitate can be separated from the zinc sulfate solution, so that the purity of the zinc sulfate solution is higher. Moreover, by using the combination of zinc fluoride and the alkaline zinc-containing substance, other cation impurities are not introduced. Thus, the method provided by the present application can effectively reduce the content of calcium ions and magnesium ions in the zinc sulfate solution, and will not introduce other cation impurities, and can also control the content of fluoride ions in the zinc sulfate solution to avoid the corrosion of the pipeline by fluoride ions.

[0007] In addition, the method according to the above-mentioned embodiments of the present application can have the following additional technical features:

[0008] In some embodiments of the present application, the method comprises: mixing the zinc sulfate solution and zinc fluoride, first heating reaction to obtain a first mixed solution; mixing the first mixed solution with the alkaline zinc-containing substance, second heating reaction, and filtering to obtain the zinc sulfate solution. Thus, the content of calcium ions and magnesium ions in the zinc sulfate solution can be effectively reduced, and other cation impurities will not be introduced, and the content of fluoride ions in the zinc sulfate solution can also be controlled.

[0009] In some embodiments of the present application, the pH value of the zinc sulfate solution containing calcium ions and magnesium ions is 4-7. Thus, the zinc sulfate solution containing calcium ions and magnesium ions can be stabilized, so that zinc ions, calcium ions and magnesium ions exist in the solution in the form of ions, which is beneficial to the subsequent precipitation reaction.

[0010] In some embodiments of the present application, the mass concentration of zinc ions in the zinc sulfate solution is 20 g / L-60 g / L. Thus, the uniformity and stability of the zinc sulfate solution can be ensured.

[0011] In some embodiments of the present application, the mass concentration of calcium ions in the zinc sulfate solution is 450 mg / L-730 mg / L, and the mass concentration of magnesium ions is 370 mg / L-730 mg / L. Thus, the reaction between the used removing agent (such as zinc fluoride) and calcium ions and magnesium ions can be more accurately and effectively carried out.

[0012] In some embodiments of the present application, the alkaline zinc-containing substance comprises at least one of zinc oxide and zinc hydroxide. Thus, the fluoride ions in the solution can be adsorbed and entrained, and the concentration of fluoride ions in the zinc sulfate solution can be stabilized to avoid the corrosion of the pipeline by fluoride ions.

[0013] In some embodiments of the present application, the mass of the zinc fluoride is a, the volume of the zinc sulfate solution containing calcium ions and magnesium ions is V, wherein a / V = 1.5 g / L-2 g / L. In this way, the balance between ions can be regulated, so as to control the speed and degree of precipitation.

[0014] In some embodiments of the present application, the mass of the zinc-containing basic substance is b, the volume of the zinc sulfate solution containing calcium ions and magnesium ions is V, wherein b / V = 3.5 g / L-4 g / L. In this way, the hydrolysis reaction of zinc ions in the zinc-containing basic substance to generate zinc hydroxide precipitation is facilitated, which in turn can adsorb and entrain fluoride ions in the solution, stabilize the concentration of fluoride ions in the zinc sulfate solution, and avoid corrosion of the pipeline by fluoride ions.

[0015] In some embodiments of the present application, the temperature of the first reaction is 50-60°C, and the time of the first reaction is 2-2.5 h. In this way, the speed of the reaction can be effectively controlled, so as to obtain the required reaction rate and reaction degree.

[0016] In some embodiments of the present application, the temperature of the second reaction is 50-60°C, and the time of the second reaction is 2.5-3 h. In this way, the speed of the reaction can be effectively controlled, so as to obtain the required reaction rate and reaction degree.

[0017] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter in the description. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0019] Figure 1 A flow chart of removing calcium and magnesium ions from a zinc sulfate solution according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0020] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0021] The present application proposes a method for removing calcium and magnesium ions from a zinc sulfate solution to prolong the working time of an evaporator. According to an embodiment of the present application, with reference to Figure 1 , the method comprises:

[0022] The zinc sulfate solution, zinc fluoride and the basic zinc-containing substance are mixed to react, and the zinc sulfate solution is obtained by filtering.

[0023] According to the method of the above embodiment of the present application, by mixing the zinc sulfate solution, zinc fluoride and the basic zinc-containing substance, the zinc fluoride in the zinc sulfate solution can dissociate fluorine ions (F - ), which can react with calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ) in the zinc sulfate solution to generate insoluble fluoride precipitates (calcium fluoride (CaF2) and magnesium fluoride (MgF2)), while zinc ions (Zn 2+ ) in the basic zinc-containing substance can combine with hydroxyl ions (OH - ) in the solution to generate zinc hydroxide precipitates by hydrolysis, the zinc hydroxide precipitates have a large surface area and adsorption capacity, can adsorb and entrain fluorine ions in the solution, can reduce the concentration of fluorine ions in the zinc sulfate solution, can stably maintain the mass concentration of fluorine ions in the zinc sulfate solution below 100 mg / L, and can avoid corrosion of the pipeline by fluorine ions, and further by filtering operation, the generated fluoride precipitates and zinc hydroxide precipitates can be separated from the zinc sulfate solution, so that the zinc sulfate solution with high purity is obtained. Moreover, by using the combination of zinc fluoride and the basic zinc-containing substance, no other cation impurities are introduced. Thus, the method provided by the present application can effectively reduce the content of calcium ions and magnesium ions in the zinc sulfate solution, and can also control the content of fluorine ions in the zinc sulfate solution without introducing other cation impurities.

[0024] According to some specific embodiments of the present application, the method comprises:

[0025] S1, mixing the zinc sulfate solution and zinc fluoride to perform a first reaction to obtain a first mixed solution.

[0026] In this step, by mixing the zinc sulfate solution and zinc fluoride, the fluorine ions in the zinc fluoride have a strong combination ability with calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ) in the zinc sulfate solution, can form insoluble fluoride precipitates (such as calcium fluoride (CaF2) and magnesium fluoride (MgF2)), while the zinc sulfate (ZnSO4) in the solution will not form insoluble substances with fluorine ions, and will remain in the solution, and thus the first mixed solution can be obtained.

[0027] According to some specific embodiments of the present application, the pH value of the zinc sulfate solution is 4-7. For example, it can be 4, 5, 6, 7, etc. The pH value of the zinc sulfate solution containing calcium ions and magnesium ions is in the above range, which can stabilize the zinc sulfate solution containing calcium ions and magnesium ions, so that zinc ions, calcium ions and magnesium ions exist in the solution in the form of ions, which is conducive to the subsequent precipitation reaction.

[0028] According to one specific example of the present application, the mass concentration of zinc ions in the zinc sulfate solution is 20g / L-60g / L. For example, it can be 20g / L, 40g / L, 60g / L, etc. There is a certain chemical equilibrium between zinc ions and sulfate ions in the zinc sulfate solution. By limiting the mass concentration of zinc ions within the above range, the equilibrium state between zinc ions and sulfate ions can be maintained, thereby ensuring the uniformity of the zinc sulfate solution. If the concentration of zinc ions is too high or too low, the balance can be broken, leading to instability of the solution properties. Thus, the uniformity and stability of the zinc sulfate solution can be ensured.

[0029] According to one specific example of the present application, the mass concentration of calcium ions in the zinc sulfate solution is 450mg / L-730mg / L, and the mass concentration of magnesium ions is 370mg / L-730mg / L. For example, the mass concentration of calcium ions can be 450mg / L, 560mg / L, 670mg / L, 730mg / L, etc., and the mass concentration of magnesium ions can be 370mg / L, 470mg / L, 570mg / L, 670mg / L, 730mg / L, etc. By limiting the mass concentration of calcium ions and the mass concentration of magnesium ions within the above range, it can be ensured that the reaction between the removal agent (such as zinc fluoride) used and calcium ions and magnesium ions can be more precise and more effective, thereby reducing the processing time and the amount of reagent required, and thus improving the efficiency of the entire process.

[0030] According to some specific embodiments of the present application, the mass of the zinc fluoride is a, and the volume of the zinc sulfate solution containing calcium ions and magnesium ions is V, wherein a / V = 1.5g / L-2g / L, for example, it can be 1.5g / L, 1.7g / L, 1.8g / L, etc. Fluoride ions in zinc fluoride can interact with calcium ions and magnesium ions in the solution to form corresponding fluoride precipitates. By controlling the amount of zinc fluoride added, the balance between ions can be regulated, thereby controlling the removal rate of calcium ions and magnesium ions.

[0031] According to some specific embodiments of the present application, the temperature of the first reaction is 50℃-60℃. For example, it can be 50℃, 53℃, 55℃, 58℃, 60℃, etc. By limiting the temperature of the first reaction within the above range, the speed of the reaction can be effectively controlled, thereby obtaining the required reaction rate and reaction degree.

[0032] According to some embodiments of the present application, the first reaction time is 2h-2.5h. For example, it can be 2h, 2.1h, 2.3h, 2.5h, etc. By limiting the first reaction time within the above range, it can be ensured that the reaction proceeds to an appropriate stage, and the desired product and reaction effect are obtained.

[0033] S2, mixing the first mixed solution with a basic zinc-containing substance to perform a second reaction, and filtering to obtain an evolved zinc sulfate solution.

[0034] In this step, by mixing the first mixed solution with a basic zinc-containing substance, on the one hand, zinc ions (Zn 2+ ) in the basic zinc-containing substance can undergo a hydrolysis reaction to generate zinc hydroxide precipitate, which has a large surface area and adsorption capacity, can adsorb and entrain fluoride ions in the solution, can stabilize the concentration of fluoride ions in the zinc sulfate solution, and avoids corrosion of the pipeline by fluoride ions; on the other hand, the basic zinc-containing substance (such as zinc hydroxide) can partially adsorb calcium and magnesium ions in the solution, thereby reducing the content of calcium and magnesium ions in the solution. Finally, through the filtering operation, the generated fluoride precipitate and zinc hydroxide precipitate can be separated from the zinc sulfate solution, thereby obtaining a purified zinc sulfate solution.

[0035] Further, the purified zinc sulfate solution is evaporated and crystallized by using an evaporator, and zinc sulfate heptahydrate solid can be obtained. In the prior art, as the evaporator continuously operates, scale will appear on the inner wall of the tube, which will further cause the tube to be blocked, and the heat conversion efficiency of the evaporator will decrease, the energy consumption will increase, and the evaporation capacity will decrease. The main component of the scale on the inner wall is calcium sulfate. Therefore, by using the method for removing calcium and magnesium ions in the zinc sulfate solution provided in the present application, the content of calcium ions in the zinc sulfate solution can be effectively removed, thereby delaying the scale formation on the inner wall of the evaporator and prolonging the working time of the evaporator.

[0036] According to some embodiments of the present application, the mass of the basic zinc-containing substance is b, and the volume of the zinc sulfate solution containing calcium ions and magnesium ions is V, wherein b / V=3.5g / L-4g / L. For example, it can be 3.5g / L, 3.7g / L, 3.9g / L, 4g / L, etc. By limiting the content of the basic zinc-containing substance within the above range, it is beneficial for zinc ions in the basic zinc-containing substance to undergo a hydrolysis reaction to generate zinc hydroxide precipitate, which can further adsorb and entrain fluoride ions in the solution, can stabilize the concentration of fluoride ions in the zinc sulfate solution, avoids corrosion of the pipeline by fluoride ions, and can also reduce the cost.

[0037] According to some embodiments of the present application, the basic zinc-containing substance includes at least one of zinc oxide and zinc hydroxide. When zinc oxide is added into the zinc sulfate solution, zinc ions will combine with hydroxyl ions in the solution to generate zinc hydroxide precipitate through hydrolysis reaction. The zinc oxide precipitate has a large surface area and adsorption capacity, and can adsorb and entrain fluorine ions in the solution to form larger particles, and finally remove the fluorine ions from the solution through precipitation. The zinc hydroxide has good dispersion and colloidal properties in the zinc sulfate solution, and can form small flocculation bodies to adsorb and entrain fluorine ions in the solution. As the zinc hydroxide flocculation bodies continue to grow and settle, the adsorbed fluorine ions are also removed from the solution. Moreover, the above-mentioned basic zinc-containing substance is alkaline in the solution, and can adjust the pH value of the zinc sulfate solution to make the precipitation of fluorides (such as magnesium fluoride and calcium fluoride) more complete. Therefore, by selecting the above-mentioned basic zinc-containing substance, the fluorine ions in the zinc sulfate solution can be effectively reduced, and the mass concentration of the fluorine ions in the zinc sulfate solution can be stably maintained below 100 mg / L to avoid serious corrosion of the pipeline.

[0038] According to some embodiments of the present application, the temperature of the second reaction is 50-60°C, for example, can be 50°C, 53°C, 55°C, 58°C, 60°C, etc. By limiting the temperature of the second reaction within the above range, the progress speed of the reaction can be effectively controlled, so as to obtain the required reaction rate and reaction degree.

[0039] According to some embodiments of the present application, the time of the second reaction is 2.5-3h, for example, can be 2.5h, 2.7h, 2.9h, 3h, etc. By limiting the time of the second reaction within the above range, it can be ensured that the reaction proceeds to an appropriate stage to obtain the required product and reaction effect.

[0040] According to the method of the above embodiments of the present application, the zinc sulfate solution containing calcium ions and magnesium ions is mixed with zinc fluoride to perform the first reaction. The zinc fluoride will dissociate fluorine ions (F - ) in the zinc sulfate solution. The fluorine ions can react with calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ) in the zinc sulfate solution to generate difficultly soluble fluoride precipitates (calcium fluoride (CaF2) and magnesium fluoride (MgF2), etc.). Then, the basic zinc-containing substance is mixed to perform the second reaction. The zinc ions (Zn 2+ ) in the basic zinc-containing substance will combine with hydroxyl ions (OH -) combined, a hydrolysis reaction occurs to generate zinc hydroxide precipitation, the zinc hydroxide precipitation has a large surface area and adsorption capacity, can adsorb and entrain fluoride ions in the solution, can stabilize the concentration of fluoride ions in the zinc sulfate solution, avoids the corrosion of the pipeline by fluoride ions, and further through the filtration operation, the generated fluoride precipitate and zinc hydroxide precipitate can be separated from the zinc sulfate solution, so that a zinc sulfate solution with high purity is obtained. Moreover, by using the combination of zinc fluoride and the basic zinc-containing substance, no other cation impurities are introduced. Thus, the method provided in the present application can effectively reduce the content of calcium ions and magnesium ions in the zinc sulfate solution, and will not introduce other cation impurities, and can also control the content of fluoride ions in the zinc sulfate solution, thereby avoiding the corrosion of the pipeline by fluoride ions.

[0041] The scheme of the present disclosure will be explained below in conjunction with examples. Those skilled in the art will understand that the following examples are only for illustrating the present disclosure, and should not be regarded as limiting the scope of the present disclosure. If the specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0042] Example 1

[0043] 1) The zinc sulfate solution was placed in a secondary displacement tank, heated to 60℃ and kept the temperature unchanged, 1.5g / L of zinc fluoride was added, and after stirring for 2 hours, a first mixed solution was obtained, wherein the pH of the zinc sulfate solution containing calcium ions and magnesium ions was 6.

[0044] 2) 3.5g / L of zinc oxide was further added to the mixed solution obtained in step 1), the solution temperature was kept at 60℃, and stirring was carried out for 2.5 hours. After the reaction was completed, pressure filtration was carried out, the filter residue was calcium and magnesium removal residue, and the filtrate was zinc sulfate solution. The zinc sulfate solution was then placed in an evaporator for concentration. When the mass concentration of the zinc sulfate solution reached 1.62g / L, the material was discharged. The discharged zinc sulfate solution was placed in a crystallization kettle for crystallization treatment, and finally, seven-water zinc sulfate solid was obtained by centrifugal drying.

[0045] Example 2

[0046] The difference between Example 2 and Example 1 is that:

[0047] 1) The zinc sulfate solution was placed in a secondary displacement tank, heated to 60℃ and kept the temperature unchanged, 1.5g / L of zinc fluoride was added, and after stirring for 2 hours, a first mixed solution was obtained, wherein the pH of the zinc sulfate solution containing calcium ions and magnesium ions was 6.

[0048] Example 3

[0049] The difference between Example 3 and Example 1 is that:

[0050] 1) The zinc sulfate solution is placed in a secondary displacement tank, the temperature is raised to 60°C and kept constant, 0.5 g / L of zinc fluoride is added, and after stirring for 2 hours, a first mixed solution is obtained, wherein the pH of the zinc sulfate solution containing calcium ions and magnesium ions is 6.

[0051] Example 4

[0052] The difference between Example 4 and Example 1 is that:

[0053] 2) To the mixed solution obtained in step 1), 3 g / L of zinc oxide is added, the solution temperature is kept at 60°C, and stirring is carried out for 2.5 hours. After the reaction is completed, pressure filtration is carried out, the filter residue is a calcium and magnesium removal residue, and the filtrate is a zinc sulfate solution. The zinc sulfate solution is then placed in an evaporator for concentration. When the mass concentration of the zinc sulfate solution reaches 1.62 g / L, the material is discharged. The discharged zinc sulfate solution is placed in a crystallization kettle for crystallization treatment, and finally centrifugal drying is carried out to obtain a zinc sulfate heptahydrate solid.

[0054] Example 5

[0055] The difference between Example 5 and Example 1 is that:

[0056] 2) To the mixed solution obtained in step 1), 2 g / L of zinc oxide is added, the solution temperature is kept at 60°C, and stirring is carried out for 2.5 hours. After the reaction is completed, pressure filtration is carried out, the filter residue is a calcium and magnesium removal residue, and the filtrate is a zinc sulfate solution. The zinc sulfate solution is then placed in an evaporator for concentration. When the mass concentration of the zinc sulfate solution reaches 1.62 g / L, the material is discharged. The discharged zinc sulfate solution is placed in a crystallization kettle for crystallization treatment, and finally centrifugal drying is carried out to obtain a zinc sulfate heptahydrate solid.

[0057] Comparative Example 1

[0058] Except that step 1) in Example 1 is deleted, the rest is the same as Example 1.

[0059] Comparative Example 2

[0060] Except that step 2) in Example 1 is deleted, the rest is the same as Example 1.

[0061] Test and analysis

[0062] Under the same conditions, the mass concentrations of calcium ions, magnesium ions and fluoride ions in the sulfuric acid solutions obtained in Examples 1-8 and Comparative Examples 1-2 above are measured, and the removal efficiency of calcium ions and magnesium ions is calculated. The specific test method is as follows:

[0063] Calcium ion measurement and calcium ion removal efficiency: 50 ml of the solution to be measured was taken, 2.5 ml of HCl was added, and the solution was digested to 20-30 ml on an electric stove, then washed into a 50 ml volumetric flask, and measured by ICP;

[0064] The calcium concentrations in the zinc sulfate solution were C1, respectively, and the calcium concentration of the solution after calcium and magnesium removal was C2. The solution volume changed little during the calcium and magnesium removal process, i.e., the removal rate of calcium ions was (1-C2 / C1).

[0065] Magnesium ion measurement and magnesium ion removal efficiency: 50 ml of the solution to be measured was taken, 2.5 ml of HCl was added, and the solution was digested to 20-30 ml on an electric stove, then washed into a 50 ml volumetric flask, and measured by ICP;

[0066] The magnesium concentrations in the zinc sulfate solution were C3, respectively, and the magnesium concentration of the solution after calcium and magnesium removal was C4. The solution volume changed little during the calcium and magnesium removal process, i.e., the removal rate of magnesium ions was (1-C4 / C3).

[0067] Fluoride ion measurement: 1 ml of the solution to be measured was taken, 15 ml of sodium citrate, 2 drops of phenolphthalein were added to a 100 ml volumetric flask, the solution was adjusted to beer color with sodium hydroxide, 5 ml of triethanolamine solution was then added, and the solution was diluted to 100 ml with water, and then measured by a fluoride ion potentiometer;

[0068] The calculation results are shown in Table 1:

[0069] Table 1

[0070]

[0071]

[0072] According to Table 1, compared with Comparative Examples 1-2, in Examples 1-8, when the zinc fluoride concentration reaches 1.5 g / L, the calcium removal rate can reach more than 50%, and when the zinc oxide concentration reaches 3.5 g / L, the fluorine content in the solution is less than 100 mg / L. Thus, the method provided in the application can effectively reduce the content of calcium ions and magnesium ions in the zinc sulfate solution, without introducing other cation impurities, and can also control the content of fluoride ions in the zinc sulfate solution, avoiding corrosion of fluoride ions to the pipeline.

[0073] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", "some implementations" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples, without contradiction.

[0074] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method for removing calcium and magnesium ions from a zinc sulfate solution to extend the operating time of an evaporator, characterized in that, The application relates to a method for purifying a zinc sulfate solution containing calcium ions and magnesium ions. The zinc sulfate solution, zinc fluoride and the basic zinc-containing substance are mixed to react, and then filtered to obtain the zinc sulfate solution.

2. The method of claim 1, wherein, The zinc sulfate solution and the zinc fluoride are mixed to perform a first reaction, and then a first mixed solution is obtained. The first mixed solution and the basic zinc-containing substance are mixed to perform a second reaction, and then filtered to obtain a purified zinc sulfate solution. The zinc sulfate solution containing calcium ions and magnesium ions has a pH value of 4-7.

3. The method according to claim 1 or 2, characterized in that, The basic zinc-containing substance comprises at least one of zinc oxide and zinc hydroxide.

4. The method according to claim 1 or 2, characterized in that, The mass concentration of zinc ions in the zinc sulfate solution is 20-60 g / L.

5. The method according to claim 1 or 2, characterized in that, The mass concentration of calcium ions in the zinc sulfate solution is 450-730 mg / L, and the mass concentration of magnesium ions is 370-730 mg / L.

6. The method of claim 1 or 2, wherein, The mass of the zinc fluoride is a, and the volume of the zinc sulfate solution containing calcium ions and magnesium ions is V, wherein a / V=1.5-2 g / L.

7. The method of claim 6, wherein, The mass of the basic zinc-containing substance is b, and the volume of the zinc sulfate solution containing calcium ions and magnesium ions is V, wherein b / V=3.5-4 g / L.

8. The method of claim 6, wherein, The temperature of the first reaction is 50-60 DEG C, and the time of the first reaction is 2-2.5 h.

9. The method of claim 2, wherein, The temperature of the second reaction is 50-60 DEG C, and the time of the second reaction is 2.5-3 h.

10. The method of claim 2, wherein, ​

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