Producing method of zinc oxide, management method of production of zinc oxide and management system of production of zinc oxide

Abstract

To sufficiently concentrate zinc when obtaining zinc oxide after passing mixing of carbonate solution to a raw liquid, even when zinc, chlorine and an organic solvent are contained in a raw liquid.SOLUTION: A method for producing zinc oxide and its related technology, further comprises: a relationship acquisition process 1 to obtain the relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions before or during the mixing process; a relationship acquisition process 2 to obtain the relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions; and an adjustment process to add water to the mixed solution during the mixing process or to the original solution before the mixing process, so that the volume ratio of the organic solvent decreases in order for the solubilities of zinc ions and carbonate ions in relations 1 and 2 to become equal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing zinc oxide, a method for managing the production of zinc oxide, and a system for managing the production of zinc oxide. [Background technology]

[0002] Claim 1 of Patent Document 1 describes a method of recovering zinc by limiting the aluminum concentration in a zinc chloride solution with a high chlorine concentration and adding sodium carbonate to the solution at a pH of 6 or higher to precipitate basic zinc carbonate.

[0003] Paragraph 0028 of Patent Document 1 describes the following: Sodium carbonate is added to a zinc-containing hydrochloric acid solution in which the aluminum concentration has been reduced to 200 mg / L or less, and the solution is stirred to adjust the pH to 6 or higher, preferably 8 or higher. The zinc compound contained in the solution is hydrolyzed to form a precipitate of basic zinc carbonate [Zn5(CO3)2(OH)6]. Most of the aluminum in the solution and the sodium from the sodium carbonate remain in the solution, and only a small amount, generally 0.1 wt% (expressed as % by mass in this specification), is mixed into the precipitate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-138490 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors' investigations revealed the following problems.

[0006] When the solution to be treated, which contains zinc and chlorine, consists of only an aqueous phase, as in the examples of Patent Document 1, the amount of sodium precipitate mixed in is small if the technology described in Patent Document 1 is used. In this specification, the solution to be treated is also referred to as the raw solution.

[0007] On the other hand, the inventors' investigations have revealed that when the raw solution to be treated contains a large amount of organic solvent to the extent that it forms a phase, the amount of sodium precipitated increases to a non-negligible extent even when the technology described in Patent Document 1 is used. In other words, when the raw solution to be treated contains a large amount of organic solvent to the extent that it forms a phase, the zinc concentration expected from the example in Patent Document 1 in which the treatment target consists of only an aqueous phase cannot be obtained, and zinc is diluted.

[0008] An object of the present invention is to provide a technology for sufficiently concentrating zinc when obtaining zinc oxide after mixing a carbonate solution with a stock solution, even if the stock solution contains zinc, chlorine, and an organic solvent. [Means for solving the problem]

[0009] The first invention to solve the above-mentioned problems is: a mixing step of mixing a stock solution containing zinc, chlorine, and an organic solvent with a carbonate solution to obtain a mixed solution; a solid-liquid separation step of recovering the precipitate obtained in the mixing step; a drying step of heating the precipitate to remove the organic solvent contained therein; a water washing step of washing the solid matter obtained in the drying step with water; and Before or during the mixing step, a relationship obtaining step 1 for obtaining a relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions; a relationship obtaining step 2 for obtaining a relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions; an adjusting step of adding water to the mixed solution during the mixing step or to the stock solution before the mixing step so as to reduce the volume ratio of the organic solvent to the mixed solution from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; The method for producing zinc oxide further comprises:

[0010] The second invention is: The method for producing zinc oxide according to the first aspect of the present invention, wherein in the adjusting step, the volume ratio of the organic solvent in the mixed solution to the volume of the mixed solution is set to 0.2 or less.

[0011] The third invention is In the method for producing zinc oxide according to the first or second invention, the stock solution before the adjusting step contains 10% or more zinc by mass.

[0012] The fourth invention is In the method for producing zinc oxide according to any one of the first to third aspects of the present invention, the stock solution before the adjusting step contains 10 to 25% by mass of zinc.

[0013] The fifth invention is The method for producing zinc oxide according to any one of the first to fourth aspects of the present invention, wherein the volume ratio of the organic solvent to the stock solution before the adjusting step is 0.45 or more.

[0014] The sixth invention is 6. The method for producing zinc oxide according to any one of 1 to 5, wherein the organic solvent contains an alcohol.

[0015] The seventh invention is The method for producing zinc oxide according to any one of the first to sixth aspects of the present invention, wherein the carbonate is at least one selected from the group consisting of sodium carbonate, potassium carbonate, calcium carbonate, and ammonium carbonate.

[0016] The eighth invention is The method for producing zinc oxide according to any one of the first to seventh aspects of the present invention, wherein the heating temperature in the drying step is 80°C or higher and lower than 500°C.

[0017] The ninth invention is The water washing step a repulping step in which the solid material is crushed and washed by stirring with water in an amount of a solid-liquid mass ratio of 1:1 or more; a dehydration step of dehydrating the solid material obtained in the repulping step; a washing step of passing water through the dehydrated material obtained in the dehydration step to wash it; The method for producing zinc oxide according to any one of the first to eighth aspects of the present invention comprises:

[0018] The tenth invention is 1. A method for controlling the production of zinc oxide from a precipitate obtained from a mixture of a stock solution containing zinc, chlorine, and an organic solvent and a carbonate solution, comprising: When or before obtaining the mixed solution, a relationship obtaining step 1 for obtaining a relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions; a relationship obtaining step 2 for obtaining a relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions; an adjusting step of adding water to the mixed solution during the mixing step or to the stock solution before the mixing step so as to reduce the volume ratio of the organic solvent to the mixed solution from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; The present invention relates to a method for controlling the production of zinc oxide, comprising:

[0019] The eleventh invention is 1. A management system for producing zinc oxide from a precipitate obtained from a mixed solution obtained by mixing a raw solution containing zinc, chlorine, and an organic solvent with a carbonate solution, comprising: When or before obtaining the mixed solution, a relationship acquisition unit (part 1) for acquiring a relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions; a relationship acquisition unit (part 2) for acquiring a relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions; an adjusting unit that adds water to the mixed solution during the mixing step or to the raw solution before the mixing step so as to decrease the volume ratio of the organic solvent to the mixed solution from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; The present invention relates to a zinc oxide production management system comprising: [Effects of the Invention]

[0020] According to the present invention, even if zinc, chlorine, and an organic solvent are contained in the raw solution, zinc can be sufficiently concentrated when zinc oxide is obtained after mixing the raw solution with a carbonate solution. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a flowchart of the method for producing zinc oxide according to this embodiment. [Figure 2] FIG. 2 is a plot showing Relationship 1 and Relationship 2 together for the stock solution (25° C.) used in Example 1. [Figure 3] FIG. 3 is a plot showing Relationship 1 and Relationship 2 together for the stock solution (50° C.) used in Example 1. [Figure 4] FIG. 4 is a schematic block diagram of a management system for zinc oxide production according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] This embodiment will be described below. The symbol "to" indicates a value greater than or equal to a predetermined value and less than or equal to a predetermined value. This embodiment will be described in the following order.

[0023] FIG. 1 is a flowchart of the method for producing zinc oxide according to this embodiment.

[0024] The method for producing zinc oxide according to this embodiment includes a mixing step of mixing a stock solution containing zinc, chlorine, and an organic solvent with a carbonate solution to prepare a mixed solution, a solid-liquid separation step of recovering a precipitate obtained in the mixing step, a drying step of removing the organic solvent contained in the precipitate by heating, and a water-washing step of washing with water a solid obtained after the drying step.

[0025] In addition, in this embodiment, an adjustment step of reducing the volume ratio of the organic solvent to the stock solution is carried out before or during the mixing step so that a carbonate equivalent to or greater than the molar equivalent of zinc in the stock solution is dissolved.

[0026] The amount of water to be added to the mixture in the preparation step is determined by the following steps. A relationship obtaining step 1 for obtaining a relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions A relationship obtaining step 2 for obtaining a relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions The volume of the mixed solution handled in relationship acquisition steps 1 and 2 may be obtained from the volume of the stock solution and the volume of the carbonate solution that are actually mixed (relationship acquisition steps 1 and 2 during the mixing step), or may be obtained from the volume of the stock solution and the volume of the carbonate solution that are planned to be mixed (relationship acquisition steps 1 and 2 before the mixing step). Then, water whose amount to be added has been determined may be added to the actually obtained mixed solution (adjustment step during the mixing step), or water whose amount to be added may be added before the mixing step (adjustment step before the mixing step).

[0027] Then, in the adjustment step, water is added to the mixed solution during the mixing step (or the stock solution before the mixing step) so that the volume ratio of the organic solvent to the mixed solution is reduced from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2.

[0028] An example of Relationship 1 is a plot (or an approximate straight line or curve) of the volume ratio of the organic solvent to the total stock solution on the horizontal axis and the solubility of zinc ions (solubility at 25°C, hereinafter the same) on the vertical axis (unit: mol / L).

[0029] An example of Relationship 2 is a plot (or an approximate straight line or curve) in which the horizontal axis represents the volume ratio of the organic solvent to the entire stock solution, and the vertical axis represents the solubility of carbonate ions (solubility at 25°C, the same applies hereinafter) when dissolving sodium carbonate in water to obtain an aqueous sodium carbonate solution (unit: mol / L).

[0030] FIG. 2 is a plot showing Relationship 1 and Relationship 2 together for the stock solution (25° C.) used in Example 1 below.

[0031] 2, the horizontal axis value at the intersection of the approximate line or curve between Relationship 1 (Plot 1) and Relationship 2 (Plot 2) is approximately 0.15. In the adjusting step, water is added to the mixed solution during the mixing step (or the stock solution before the mixing step) so that the volume ratio of the organic solvent to the mixed solution of the stock solution and the carbonate solution becomes 0.15 or less (e.g., 0.14). In Figure 3, the horizontal axis value at the intersection of the approximate line or curve between Relationship 1 (Plot 1) and Relationship 2 (Plot 2) is approximately 0.20. In the adjustment step, water is added to the mixed solution during the mixing step (or the stock solution before the mixing step) so that the volume ratio of the organic solvent to the mixed solution of the stock solution and the carbonate solution becomes 0.20 or less (e.g., 0.19). As described above, the volume ratio varies depending on the temperature of the raw solution, but in the present invention, it is preferable to adjust the volume ratio of the organic solvent in the mixed solution to 0.2 or less.

[0032] Incidentally, in Example 1 described below, 600 mL of pure water is added to 100 mL of a slurry containing 27.5% zinc in terms of zinc chloride (ZnCl2). There are no limitations on what can be added as long as it is an aqueous phase, and it does not have to be water. For example, as mentioned above, it may be an aqueous sodium carbonate solution in which sodium carbonate has been dissolved in water in advance.

[0033] The above phrase "the volume ratio of the organic solvent to the mixed solution is reduced from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal" means that the volume ratio of the organic solvent is reduced in this way.

[0034] In actual operations, the temperature of the raw solution may not be 25°C. For example, the temperature of the raw solution may be intentionally increased to improve work efficiency. In such cases, the solubility value for 25°C can be converted based on the actual temperature of the raw solution.

[0035] FIG. 3 is a plot showing Relationship 1 and Relationship 2 together for the stock solution (50° C.) used in Example 1 below.

[0036] In the example shown in Figure 3, 400 mL of pure water is needed for 100 mL of slurry containing 27.5% zinc in terms of zinc chloride (ZnCl2). In other words, the amount of water used can be reduced to two-thirds compared to when the temperature is 25°C.

[0037] Furthermore, if the slurry is not the above, the shapes of plots 1 and 2 shown in Figure 2 will also change. If the slurry is not the above, it is sufficient to obtain plots 1 and 2 depending on the type of raw solution to be treated. This also applies when the type of carbonate is changed.

[0038] In Figure 2, plot 1 and plot 2 intersect. Normally, the solubility of zinc ions increases when the volume ratio of organic solvent to the total stock solution is increased. Normally, the solubility of carbonate ions decreases when the volume ratio of organic solvent to the total stock solution is increased. Therefore, the two plots will normally intersect, regardless of the type of stock solution before the adjustment process.

[0039] By undergoing this adjustment process, even if the raw solution to be treated contains an organic solvent, carbonate can be sufficiently dissolved in the raw solution, and as a result, zinc in the raw solution can be sufficiently precipitated as zinc carbonate, ultimately enabling the zinc to be concentrated during the production of zinc oxide. In addition, since the carbonate is already dissolved in the carbonate (water) solution, the expression "the carbonate solution is thoroughly mixed into the stock solution" may be used instead of the expression "the carbonate is thoroughly dissolved in the stock solution." Although both expressions are used in this specification, they have the same meaning.

[0040] If the adjustment step is not performed, the carbonate solution mixed in the mixing step may not be sufficiently mixed with the stock solution due to the organic solvent contained in the stock solution, which makes it difficult to produce zinc carbonate from the stock solution as described in Patent Document 1.

[0041] On the other hand, in this embodiment, the volume ratio of the organic solvent to the stock solution is reduced in the adjusting step so that the carbonate in the mixed solution is dissolved in an amount equal to or greater than the molar equivalent of the zinc in the stock solution, and as a result, the carbonate solution mixed in the mixing step can be sufficiently mixed with the stock solution, making it easier to produce zinc carbonate from the mixed solution.

[0042] Furthermore, the method has the following effect: Even if zinc chloride is dissolved in the organic solvent in the stock solution before the mixing step, the volume ratio of the organic solvent to the stock solution is reduced in the adjusting step, so that zinc ions in the organic solvent are more likely to migrate to the aqueous phase, making it easier to produce zinc carbonate from the stock solution.

[0043] As a result, according to the method for producing zinc oxide of this embodiment, even if zinc, chlorine, and an organic solvent are contained in the raw solution, zinc can be sufficiently concentrated when zinc oxide is obtained after mixing the raw solution with a carbonate solution.

[0044] In the mixing step, the stock solution containing zinc, chlorine, and an organic solvent is mixed with the carbonate solution. There is no limitation on the "stock solution containing zinc, chlorine, and an organic solvent."

[0045] An example of the raw liquid is waste liquid generated in the manufacturing process of an organic synthetic catalyst or a refrigerant. Hereinafter, the raw liquid will be referred to as such an example. Specifically, a slurry containing zinc chloride and an organic solvent (alcohol) is treated as the raw liquid to be treated in the zinc oxide manufacturing method according to this embodiment.

[0046] Another example of the stock solution is that described in Patent Document 1. Specifically, a metal oxide (crude zinc oxide) containing zinc as the main component is obtained by heat-treating ironworks dust in a reduction furnace, a reduction roasting furnace, or the like. This crude zinc oxide contains a large amount of chlorine. The crude zinc oxide is then heated to volatilize and separate chlorides containing lead and zinc, and the resulting solution can be leached with warm water to use as the stock solution.

[0047] There are no limitations on the pH of the stock solution before the mixing step, but for example, in the case of the above-mentioned slurry, the pH is less than 4 (or 1 or less). In the mixing step, the stock solution is mixed with a carbonate solution in which carbonate (sodium carbonate) is dissolved, and the pH of the mixed solution increases. Specific pH values are listed in the Examples section below.

[0048] The carbonate solution may be mixed with the stock solution by adding the carbonate solution to the stock solution, or by adding the stock solution to the carbonate solution. Specific operations in the mixing step may be carried out by any known method, provided that the volume ratio of the organic solvent in the adjusting step can be reduced so that the carbonate in the mixed solution dissolves in an amount equal to or greater than the molar equivalent of zinc in the stock solution.

[0049] For example, after the stock solution is mixed with water, powdered (solid) carbonate may be added to the stock solution.

[0050] Alternatively, carbonate may be dissolved in water in advance, and then the resulting solution, i.e., carbonate solution, may be mixed with the stock solution (FIG. 1). For ease of explanation, FIG. 1 illustrates a case where the adjusting step is performed before the mixing step.

[0051] In any case, it is sufficient to reduce the volume ratio of the organic solvent so that the carbonate dissolves in an amount equal to or greater than the molar equivalent of zinc in the stock solution.

[0052] The stock solution before the preparation step may contain 10% or more (or 15% or more, or 20% or more) of zinc by mass. There is no upper limit, but examples include 30% or 27.5%.

[0053] The stock solution before the adjustment step may contain, by mass, 20 to 50% or more in terms of zinc chloride (ZnCl2), or 10 to 25% in terms of zinc.

[0054] In the stock solution before the adjusting step, the volume ratio of the organic solvent to the stock solution may be 0.45 or more.

[0055] The organic solvent may contain alcohol, or may contain alcohol as a main component. The specific composition of the alcohol is not limited, and examples of the alcohol include isopropyl alcohol, ethanol, and methanol. Hereinafter, the case where the alcohol is isopropyl alcohol (IPA) will be described as an example.

[0056] The carbonate may be at least one selected from the group consisting of sodium carbonate, potassium carbonate, calcium carbonate, and ammonium carbonate, and the main component of the carbonate may be sodium carbonate. Hereinafter, an example will be given in which the carbonate is sodium carbonate.

[0057] After the mixing process, a precipitate forms in the mixture. The main component of this precipitate is zinc carbonate-containing material (e.g., basic zinc carbonate [Zn5(CO3)2(OH)6] or zinc carbonate [ZnCO3]).

[0058] In this specification, the term "major component" refers to a substance that contains a specified compound in the highest proportion, and an example is a substance in which the proportion of the specified compound exceeds 50 mass %. The above definition of the major component can also be applied to the expression "major component" described below. When referring to an element as the major component, the above expression "compound" can be replaced with "element."

[0059] The solid-liquid separation step may be carried out by any suitable method, provided that it allows the recovery of the precipitate obtained in the mixing step. For example, known methods such as suction filtration, filter press, or centrifugation may be used.

[0060] The drying step is not limited to a specific method as long as the organic solvent contained in the precipitate can be removed by heating, and there are no limitations on the heating time or temperature, and a known drying oven may be used. The heating time may be, for example, 30 minutes (or 2 hours) to 5 hours. The heating temperature may be, for example, 80°C or higher, at which the alcohol can be removed (or 250°C or higher, at which zinc oxide can be produced from zinc carbonate), and 800°C or lower (or lower than 500°C).

[0061] During the drying process, the organic solvent is removed and the zinc carbonate is converted to zinc oxide. Even after the subsequent water washing process, the main component of the solid remains zinc oxide.

[0062] Regarding the water washing step, there is no specific limitation on the method as long as the solid obtained after the drying step can be washed with water.

[0063] The water washing step preferably includes a repulping step in which the obtained solid material is crushed and washed by stirring with water in a solid-liquid mass ratio of 1:1 or more, a dehydration step in which the solid material obtained by the repulping step is dehydrated, and a washing step in which water is passed through the dehydrated material obtained by the dehydration step to wash it. A solid-liquid mass ratio of 1:1 or more refers to water in an amount equal to or greater than the mass of the obtained solid material. There is no upper limit to the amount of water, but examples of upper limits include 1:12 or 1:8.

[0064] The repulping step can sufficiently remove impurities contained in the solid material from the solid material. The dewatering step and the washing step can further remove impurities from the solid material. The specific work contents of these steps can be performed using known methods.

[0065] There is no limitation on the number of washing steps, but from the viewpoint of concentrating zinc in the zinc oxide obtained by sufficiently removing impurities from the solid matter, it is preferable to carry out the washing step five or more times.

[0066] Incidentally, the number of washing steps may be defined based on the relationship between the amount of water retained in the cake and the amount of water used in the washing process. For example, in the washing process in Example 1 described below, the amount of water used per step was 500 mL, meaning that the total amount of water used in the washing process was 2,500 mL. However, when calculated based on the amount of water retained in the cake of the solid material subjected to the washing process in Example 1, the amount of water per step required to replace the water contained in the solid material is 420 mL. In other words, dividing the total amount of water, 2,500 mL, by 420 mL equals approximately 6. According to the above definition, it can be said that the washing process was performed six or more times in Example 1 described below.

[0067] The water washing step in this embodiment is not limited to a specific configuration as long as it can remove impurities (desalt) from the obtained solid. One example includes at least a repulping step, a subsequent dewatering step, and a subsequent washing step. For example, a dewatering step may be performed after the repulping step, and then the repulping step and dewatering step may be performed again, followed by the washing step. Furthermore, a dewatering step after the repulping step may be performed, followed by multiple washing steps. Furthermore, a repulping step and dewatering step may be performed again after multiple washing steps.

[0068] When handling solid materials in a dry system, it is necessary to separately crush the solid materials. On the other hand, when a water washing step is performed as in the method for producing zinc oxide according to the present embodiment, the solid materials are naturally crushed. In this respect, the method for producing zinc oxide according to the present embodiment is also advantageous.

[0069] An example of the specific contents of the water washing step is as follows: The material is repulped in water to form a slurry and washed. When dehydration is performed using a pressure filter, water may be added to the cake after dehydration and the cake may be dehydrated and washed again. When dehydration is performed using suction filtration or a filter press, water may be pumped into the cake after dehydration and washed. When using this embodiment, good filterability is achieved.

[0070] One of the features of the method for producing zinc oxide according to this embodiment is that after the adjusting step and the mixing step, the precipitate recovered in the solid-liquid separation step is subjected to a drying step, and then a water-washing step is carried out again.

[0071] Due to this feature, as shown in the Examples section below (Example 2), the amount of sodium precipitate mixed in can be reduced to less than one-sixth of the amount in the case where this procedure is not performed (Comparative Example 1) (Table 4 below). In other words, even if the raw solution to be treated contains a large amount of organic solvent to the extent that it forms a phase, zinc can be sufficiently concentrated.

[0072] Of course, it is expected that the amount of sodium precipitate mixed in will decrease if the water washing process is repeated, but the amount of post-washing liquid (i.e., waste liquid) used in the water washing process will become enormous.

[0073] On the other hand, in the zinc oxide manufacturing method according to the present embodiment, a repulping step and about five washing steps are sufficient. Although the amount of waste liquid increases due to the addition of water in the adjustment step, the method has the following advantages. For example, in Comparative Example 1 described later, the post-washing solution from the water-washing step contains a large amount of organic solvent. Therefore, the post-washing solution cannot be discharged as is and must be incinerated separately. On the other hand, in Example 2 described later, a drying step is performed before the water-washing step. Therefore, in Example 2 described later, the post-washing solution from the water-washing step contains a small amount of organic solvent, and can be discharged as is.

[0074] The solid material obtained after the water-washing step (for example, after the washing step) may be dried to obtain zinc oxide ((second) drying step). This drying step may also serve as a dehydration step for the solid material obtained after the washing step. Alternatively, a separate dehydration step may be performed after the water-washing step to obtain a solid material, and then the solid material may be subjected to a drying step.

[0075] The technical idea of the zinc oxide manufacturing method according to this embodiment can also be applied to inventions relating to the management of zinc oxide manufacturing. For example, apart from the zinc oxide manufacturing method, the technical idea of the zinc oxide manufacturing method according to this embodiment can also be applied to a method for managing zinc oxide manufacturing and its management system. The preferred examples and specific examples described so far can also be applied to the following:

[0076] For example, the above technical idea may be applied to a method for controlling zinc oxide production, which includes the mixing step, solid-liquid separation step, drying step, and water-washing step. The method for controlling zinc oxide production may at least include the adjustment step before or during the mixing step. The "method for controlling zinc oxide production" has the primary purpose of control, and is unrelated to the actual execution of the mixing step, solid-liquid separation step, drying step, and water-washing step.

[0077] Then, a relationship obtaining step 1 for obtaining a relationship 1 between the volume ratio of the organic solvent to the stock solution before the adjusting step and the solubility of zinc ions; a relationship obtaining step 2 for obtaining a relationship 2 between the volume ratio of the organic solvent to the stock solution before the adjusting step and the solubility of carbonate ions; an adjusting step of adding water to the stock solution before the adjusting step so that the volume ratio of the organic solvent to the stock solution is equal to or less than the volume ratio when the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; In the adjusting step, the manager may instruct the worker to add water, or the manager may issue the instruction to the manager himself, i.e., the manager may add water himself, or the manager may issue the instruction to a pump mechanism described below.

[0078] FIG. 4 is a schematic block diagram of a management system for zinc oxide production according to this embodiment.

[0079] The above technical idea may also be applied to a zinc oxide production management system 100 having the above mixing step, solid-liquid separation step, drying step, and water-washing step. The main purpose of the "zinc oxide production management system" is management, and it is not necessary to have a system configuration that actually performs the above mixing step, solid-liquid separation step, drying step, and water-washing step.

[0080] In addition, the zinc oxide production management system 100: a relationship acquisition unit (first) 210 for acquiring a relationship 1 between the volume ratio of the organic solvent to the stock solution before the adjusting step and the solubility of zinc ions; a relationship acquisition unit (part 2) 220 that acquires a relationship 2 between the volume ratio of the organic solvent to the stock solution before the adjustment step and the solubility of carbonate ions; an adjusting unit (230) that adds water to the stock solution before the adjusting step so that the volume ratio of the organic solvent to the stock solution is equal to or less than the volume ratio when the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; It is preferred that the

[0081] The relationship acquisition unit (part 1) 210, the relationship acquisition unit (part 2) 220, and the adjustment unit 230 may be performed by a calculation unit within a computer, or the control computer unit including the calculation unit may perform these roles.

[0082] The control computer unit functions as a computer device that performs information processing instructed by a specified program, and is specifically composed of a combination of a CPU (Central Processing Unit), HDD (Hard disk drive), ROM (Read Only Memory), RAM (Random Access Memory), external interface (I / F), etc.

[0083] The relationship 1 obtained by the relationship acquisition unit (first) 210 may be stored in advance on a hard disk drive in the computer, or the relationship 1 may be obtained by accessing another computer or a cloud via a public network. The same applies to the relationship 2 obtained by the relationship acquisition unit (second) 220.

[0084] Relationships 1 and 2 may be obtained in advance for each type of raw liquid to be treated. The temperature of the raw liquid may be, for example, 25°C. Relationships 1 and 2 may then be converted according to the actual temperature of the raw liquid. This conversion may be performed by the calculation unit, or relationships 1 and 2 that have already been calculated may be stored in the HDD or the like.

[0085] The adjusting unit 230 issues an instruction to a pump mechanism connected to a water tank, for example, to add a predetermined amount of water to a tank containing the concentrate.

[0086] Prior to the adjustment step, a determination step may be performed in which, based on various information about the stock solution, a determination is made as to whether the volume ratio of the organic solvent to the stock solution is equal to or less than the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2. A determination unit (not shown) may be provided as a system configuration. Then, only when the determination result indicates that "addition of water is necessary (i.e., the volume ratio of the organic solvent is to the right of the intersection of the relationship 1 and the relationship 2)," the adjustment unit 230 may issue an instruction to the pump mechanism to add a predetermined amount of water to the tank containing the stock solution.

[0087] The technical scope of the present invention is not limited to the above-described embodiments, but includes various modifications and improvements within the scope of the specific effects that can be obtained by the constituent elements of the invention and their combinations. [Example]

[0088] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0089] Example 1 The adjustment step was carried out on a slurry (total volume 400 mL) containing zinc, chlorine, and an organic solvent. The details of the raw solution to be treated in this example are as follows. ·IPA: 45% by mass content Zinc chloride: 50% by weight Liquid temperature: 40℃ pH: 0.68

[0090] The grades of zinc, chlorine, sodium, and fluorine, as well as the COD of the raw solution, are shown in Table 1 below. [Table 1]

[0091] Details of the stock solution and the adjusted solution obtained after adding water to the stock solution in the adjusting step are as follows. Based on the appearance of the stock solution, the volume of the stock solution before the adjustment process was equal to the volume of the organic solvent, i.e., the entire stock solution was considered to be the organic phase. The volume ratio of pure water added in the adjustment process to the volume of the stock solution before the adjustment process: 4 Volume ratio of the original solution to the adjusted solution: 0.2

[0092] As shown in Figure 2, an aqueous solution of sodium carbonate was added to provide a molar equivalent of carbonate ions to zinc, resulting in the formation of zinc carbonate precipitate. The pH of the mixed solution (neutralized) before the solid-liquid separation process was 5.88.

[0093] After the mixing step, a solid-liquid separation step of recovering the precipitate from the mixed liquid was carried out by suction filtration.

[0094] Thereafter, in the drying step, the precipitate was heated and dried in a heating furnace at 800°C for 2 hours without being washed.

[0095] The solid material obtained after drying and heating was reslurried (repulped again) using 2.1 L of water to give a solid-liquid mass ratio of 1:10, and then washed with water (repulping step).The solid was then dewatered by suction filtration (dewatering step), and then washed five times with 0.5 L of water to give a solid-liquid mass ratio of 1:1 (washing step).

[0096] After the washing step, the solid was dried overnight in a dryer at 105° C. The solid obtained after drying was measured in the same manner as above.

[0097] The grades of zinc, chlorine, sodium, and fluorine in the solid matter, as well as the COD, are shown in Table 2. Each grade was obtained by ICP atomic emission spectrometry. [Table 2]

[0098] In this example, TG analysis (thermogravimetry) was performed on the precipitate before the drying process. As a result, a weight loss occurred at 200 to 250°C. This is presumably due to a change in form from zinc carbonate to zinc oxide. When XRD analysis was performed on the precipitate after the drying process, zinc oxide was confirmed. Therefore, it was confirmed that zinc oxide was finally obtained in this example after the above drying process.

[0099] Below, Comparative Example 1 and Example 2 are compared. Note that Comparative Example 1 is not a prior art because an adjustment process was performed. To be precise, Comparative Example 1 is Reference Example 1. However, for the sake of comparison with Example 2, the name Comparative Example 1 is used for convenience.

[0100] (Comparative Example 1) In Comparative Example 1, the adjusting step was performed, but the precipitate obtained in the solid-liquid separation step was not subjected to the drying step. Instead, only the washing step of the water washing step was performed, and then the solid matter was subjected to the drying step (300°C, 5 hours) without undergoing the dehydration step. Details not specified are the same as in Example 1. The raw liquid to be treated in Comparative Example 1 is the same as in Example 1. Note that Comparative Example 1 is not a publicly known example because it performs the adjusting step, which is one of the features of the present invention.

[0101] Details of the stock solution and the adjusted solution obtained by adding water to the stock solution in the adjustment step are as follows. The stock solution before the adjustment process was 400 mL. The sodium carbonate solution was 2400 mL. The amount of water used in each of the five washing steps was 500 mL.

[0102] The liquid volume of the filtrate after the solid-liquid separation step and the post-wash liquid after each washing step in Comparative Example 1, as well as the grades of sodium, fluorine, chlorine, and zinc, and COD are as shown in Table 3 below. [Table 3] The grades of zinc, chlorine, sodium, and fluorine and the COD of the solid matter are as shown in Table 4 below (the same is true for Example 2). [Table 4]

[0103] Example 2 The same test as in Comparative Example 1 was carried out, except for the following points. The precipitate after the solid-liquid separation process was dried (300°C, 5 hours). A repulping process was carried out in which water was used in a solid-liquid mass ratio of 1:10 to wash the pulp, followed by the above-mentioned washing process. After the above washing process, the solid matter was subjected to a drying process (100°C, 12 hours) without undergoing a dehydration process.

[0104] The liquid volume of the filtrate after the solid-liquid separation step and the post-wash liquid after each washing step in Example 2, as well as the grades of sodium, fluorine, chlorine, and zinc, and COD are shown in Table 5 below. [Table 5]

[0105] Comparing Table 3 (Comparative Example 1) with Table 5 (Example 2), it can be seen that the amount of specific elements (zinc, chlorine, sodium, fluorine) contained in the post-washing liquid after each washing step in Example 2 is smaller, and the COD is also lower.

[0106] Table 4 also shows that, when comparing Comparative Example 1 and Example 2, the final solid (zinc oxide) obtained in Example 2 contains fewer impurity elements (chlorine, sodium, and fluorine) and has a lower COD. In Comparative Example 2, the amount of sodium precipitated in the final solid does not decrease significantly even after washing about five times. On the other hand, in Example 1, the amount of sodium precipitated in the final solid decreased significantly.

[0107] Even in Comparative Example 1, where the preparation step was performed and sodium carbonate was sufficiently dissolved in the stock solution, sodium could not be sufficiently removed and zinc could not be sufficiently concentrated relatively without the drying step and water washing step. Without the preparation step, zinc could not be concentrated at all.

[0108] In any case, according to each of the examples described so far, even if zinc, chlorine, and an organic solvent were contained in the stock solution, zinc could be sufficiently concentrated when zinc oxide was obtained after mixing the stock solution with a carbonate solution. [Explanation of symbols]

[0109] 100...Zinc oxide manufacturing management system 210...Relationship Acquisition Section (Part 1) 220...Relationship Acquisition Section (Part 2) 230...adjustment section

Claims

1. a mixing step of mixing a stock solution containing zinc, chlorine, and an organic solvent with a carbonate solution to obtain a mixed solution; a solid-liquid separation step of recovering the precipitate obtained in the mixing step; a drying step of heating the precipitate to remove the organic solvent contained therein; a water washing step of washing the solid matter obtained in the drying step with water; and Before or during the mixing step, a relationship obtaining step 1 for obtaining a relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions; a relationship obtaining step 2 for obtaining a relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions; an adjusting step of adding water to the mixed solution during the mixing step or to the stock solution before the mixing step so as to reduce the volume ratio of the organic solvent to the mixed solution from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; The method for producing zinc oxide further comprises:

2. 2. The method for producing zinc oxide according to claim 1, wherein in the adjusting step, a volume ratio of the organic solvent in the mixed solution to the volume of the mixed solution is set to 0.2 or less.

3. The method for producing zinc oxide according to claim 1 or 2, wherein the stock solution before the adjusting step contains 10% or more zinc by mass ratio.

4. The method for producing zinc oxide according to claim 1 or 2, wherein the stock solution before the adjusting step contains 10 to 25% by mass of zinc.

5. 3. The method for producing zinc oxide according to claim 1, wherein the volume ratio of the organic solvent to the stock solution before the adjusting step is 0.45 or more.

6. The method for producing zinc oxide according to claim 1 or 2, wherein the organic solvent comprises an alcohol.

7. 3. The method for producing zinc oxide according to claim 1, wherein the carbonate is at least one selected from the group consisting of sodium carbonate, potassium carbonate, calcium carbonate, and ammonium carbonate.

8. The method for producing zinc oxide according to claim 1 or 2, wherein the heating temperature in the drying step is 80°C or higher and lower than 500°C.

9. The water washing step a repulping step in which the solid material is crushed and stirred and washed with water in an amount of a solid-liquid mass ratio of 1:1 or more; a dehydration step of dehydrating the solid material obtained in the repulping step; a washing step of passing water through the dehydrated material obtained in the dehydration step to wash it; The method for producing zinc oxide according to claim 1 or 2, comprising:

10. 1. A method for controlling the production of zinc oxide from a precipitate obtained from a mixture of a stock solution containing zinc, chlorine, and an organic solvent and a carbonate solution, comprising: When or before obtaining the mixed solution, a relationship obtaining step 1 for obtaining a relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions; a relationship obtaining step 2 for obtaining a relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions; an adjusting step of adding water to the mixed solution during the mixing step or to the stock solution before the mixing step so as to reduce the volume ratio of the organic solvent to the mixed solution from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; 1. A method for controlling the production of zinc oxide, comprising:

11. 1. A management system for producing zinc oxide from a precipitate obtained from a mixed solution obtained by mixing a raw solution containing zinc, chlorine, and an organic solvent with a carbonate solution, comprising: When or before obtaining the mixed solution, a relationship acquisition unit (part 1) for acquiring a relationship 1 between the volume ratio of the organic solvent in the mixed solution and the solubility of zinc ions; a relationship acquisition unit (part 2) for acquiring a relationship 2 between the volume ratio of the organic solvent in the mixed solution and the solubility of carbonate ions; an adjusting unit that adds water to the mixed solution during the mixing step or to the raw solution before the mixing step so as to decrease the volume ratio of the organic solvent to the mixed solution from the volume ratio at which the solubilities of zinc ions and carbonate ions become equal in the relationship 1 and the relationship 2; A zinc oxide production management system comprising:

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