Method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese residues

Abstract

The invention provides a method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese residues. The preparation method comprises the following steps: drying the electrolytic manganese residues and preparing the electrolytic manganese residues into electrolytic manganese residue powder; mixing the electrolytic manganese residue powder with an ammonium chloride solution, and reacting to obtain a mixed solution; carrying out solid-liquid separation on the mixed solution to obtain a first filtrate; aging the first filtrate, and separating out a filter cake; the phase of the high-purity calcium sulfate dihydrate powder is a gypsum phase, the content of the high-purity calcium sulfate dihydrate powder is larger than 99%, the whiteness of the high-purity calcium sulfate dihydrate powder is larger than 90, and the microscopic morphology of the high-purity calcium sulfate dihydrate powder comprises particles and / or plates. According to the method disclosed by the invention, all-component resource utilization of the electrolytic manganese residues can be realized; the whole preparation process of the method is carried out at low temperature and normal pressure, no wastewater is discharged, the method is green and efficient, and the additive can be recycled for multiple times.

Description

Technical Field

[0001] The present invention relates to the field of resource utilization of electrolytic manganese slag. Specifically, it relates to a method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag. Background Art

[0002] Calcium sulfate dihydrate powder is an important inorganic chemical powder and is the main raw material for manufacturing gypsum boards, gypsum powders, and gypsum products. At the same time, the hygroscopicity and biocompatibility of calcium sulfate dihydrate make it an ideal fracture fixation material, which can be used for bone transplantation and bone defect repair, promoting the regeneration and healing of bone tissue. In some compound preparations, calcium sulfate dihydrate can be used as an excipient to help stabilize drug components. Calcium sulfate dihydrate can also reduce soil alkalinity, improve soil structure, increase soil permeability and air permeability, and promote the development of plant roots.

[0003] Electrolytic manganese slag is a solid waste mainly composed of calcium sulfate dihydrate, silicon dioxide, etc. generated during the production of electrolytic manganese metal. It itself contains a large amount of calcium sulfate dihydrate and is suitable for the production of calcium sulfate dihydrate powder. Producing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag can not only realize the resource utilization of electrolytic manganese slag but also save natural gypsum resources.

[0004] So far, no research on preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag has been found, and no relevant reports on using salt solution as an auxiliary agent to prepare high-purity calcium sulfate dihydrate powder from electrolytic manganese slag under low-temperature and normal-pressure conditions as proposed in the present invention have been found. Summary of the Invention

[0005] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies existing in the prior art. For example, the purpose of the present invention is to provide a method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag.

[0006] To achieve the above purpose, the present invention provides a method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag. The preparation method includes: (1) drying the electrolytic manganese slag and making it into electrolytic manganese slag powder; (2) mixing the electrolytic manganese slag powder and ammonium chloride solution, and obtaining a mixed solution after reaction; (3) performing solid-liquid separation on the mixed solution to obtain a first filtrate; (4) aging the first filtrate and separating out a filter cake; (5) washing the filter cake and drying it to obtain high-purity calcium sulfate dihydrate powder, wherein the phase of the high-purity calcium sulfate dihydrate powder is the gypsum phase, the content is greater than 99%, and the whiteness is greater than 90.

[0007] Optionally, the concentration of the ammonium chloride solution is 1 - 5 mol / L; the ratio of the ammonium chloride solution to the electrolytic manganese slag powder is 25 - 50 mL / g.

[0008] Optionally, the reaction is carried out in a constant temperature water bath shaker with the rotation speed of the shaker being 150 - 240 r / min; the temperature of the reaction is from room temperature to 100 °C, and the time of the reaction is 2 - 60 min.

[0009] Optionally, the aging temperature is 6 - 10 °C, and the aging time is 12 - 40 h.

[0010] Optionally, the electrolytic manganese residue powder in step (1) can pass through an 80 - mesh sieve, and the drying includes drying by baking with the baking temperature not exceeding 40 °C.

[0011] Optionally, the drying temperature in step (5) does not exceed 40 °C, and drying is carried out until the adsorbed water on the surface of the calcium sulfate dihydrate powder is removed.

[0012] Optionally, a second filtrate is also separated in step (4), and the method further includes replacing all or part of the ammonium chloride solution in step (2) with the second filtrate.

[0013] Further optionally, when steps (1) - (5) are repeated until the soluble salts in the filtrate are supersaturated, ammonium chloride and ammonium sulfate in the filtrate are recovered; then the pH value is adjusted by adding ammonia water so that the enriched manganese ions in the filtrate precipitate in the form of manganese hydroxide and are separated to obtain a third filtrate, and the third filtrate can be used to prepare the ammonium chloride solution in step (2).

[0014] Optionally, the microscopic morphology of the high - purity calcium sulfate dihydrate powder includes granular and / or plate - like.

[0015] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0016] (1) Innovatively, the present invention uses ammonium chloride as an auxiliary agent to first separate and dissolve calcium sulfate dihydrate in the electrolytic manganese residue, so as to separate it from pyrite, mica, etc. that affect whiteness. And this method directly and completely utilizes the calcium sulfate dihydrate in the electrolytic manganese residue, which is essentially different from the existing partial research that only uses the calcium component to prepare calcium carbonate.

[0017] (2) The present invention uses ammonium chloride as an auxiliary agent to extract calcium sulfate dihydrate from the electrolytic manganese residue, transferring the original calcium sulfate dihydrate, ammonium magnesium sulfate, and manganese ions in the raw material into the solution, and enriching the remaining components such as pyrite, mica, and quartz that are insoluble in ammonium chloride solution. The direct reason restricting the application of electrolytic manganese residue in building materials is the large amount of soluble salts and heavy metal ions it contains. Through the dissolution of ammonium chloride in the present invention, these soluble components have been separated from components such as quartz, so that the ammonium chloride leaching residue of the electrolytic manganese residue can be directly used in the building materials field, thereby realizing the comprehensive utilization of all components of the electrolytic manganese residue.

[0018] (3) The present invention makes full use of the calcium sulfate dihydrate in the dissolved electrolytic manganese residue. The added ammonium chloride additive always exists in the solution in the form of ions and can thus be recycled for the dissolution of calcium sulfate dihydrate in the raw materials until the amount of ammonium magnesium sulfate dissolved in the filtrate continuously increases and the ammonium sulfate contained in the solution reaches supersaturation and precipitates. Therefore, the entire preparation process is carried out at low temperature and normal pressure, and the additive can be recycled multiple times. The entire process has no wastewater discharge and is green and efficient.

[0019] (4) By recycling the additive, the soluble manganese ions contained in the electrolytic manganese residue are continuously enriched in the solution and finally precipitated and recovered in the form of manganese hydroxide, realizing the recovery of the manganese ions that cause heavy metal pollution in the electrolytic manganese residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Through the following description in conjunction with the drawings, the above and other objects and / or features of the present invention will become clearer, wherein:

[0021] Figure 1 Shows the XRD pattern of the high-purity calcium sulfate dihydrate powder prepared in Example 1 of the present invention.

[0022] Figure 2 Shows the SEM image of the high-purity calcium sulfate dihydrate powder prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In the following, a method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese residue according to the present invention will be described in detail in conjunction with exemplary embodiments.

[0024] It should be noted that "first", "second", "third", etc. are only for convenience of description and easy distinction, and should not be construed as indicating or implying relative importance.

[0025] Exemplary Embodiment 1

[0026] This exemplary embodiment provides a method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese residue, and the preparation method may include:

[0027] S1. Dry the electrolytic manganese residue and make it into electrolytic manganese residue powder.

[0028] In this embodiment, the electrolytic manganese residue powder can pass through an 80-mesh sieve, and the drying may include drying in an oven, and the drying temperature does not exceed 40°C, for example, 20°C, 25°C, 36°C, and 40°C, etc.

[0029] Among them, the electrolytic manganese residue powder can pass through an 80-mesh sieve to improve the dissolution rate of calcium sulfate dihydrate in the electrolytic manganese residue, and the purpose of drying is to remove the adsorbed water of the electrolytic manganese residue.

[0030] S2. Mix the electrolytic manganese residue powder and ammonium chloride solution, and obtain a mixed solution after the reaction.

[0031] In this embodiment, the concentration of the ammonium chloride solution is 1 - 5 mol / L, such as 1 mol / L, 1.5 mol / L, 2.8 mol / L, 3.5 mol / L, 4.9 mol / L, etc.; the ratio of the ammonium chloride solution to the electrolytic manganese residue powder is 25 - 50 mL / g, such as 25 mL / g, 30 mL / g, 37 mL / g, 41 mL / g, 49 mL / g, etc.

[0032] Among them, too low a concentration of ammonium chloride is not conducive to the dissolution of calcium sulfate dihydrate in the electrolytic manganese residue, and too high a concentration of ammonium chloride is close to the supersaturation of ammonium chloride, which is not conducive to the preparation of the solution; the electrolytic manganese residue contains a large amount of soluble salts, and the addition of the ammonium chloride solution makes the concentration of the total soluble ions in the solution relatively high. Therefore, too low a liquid - solid ratio makes the concentration of soluble ions in the system relatively high, which is not conducive to the dissolution of calcium sulfate dihydrate in the electrolytic manganese residue; while too high a liquid - solid ratio will reduce the concentration of calcium ions in the system, making it difficult for calcium sulfate dihydrate to precipitate subsequently.

[0033] In this embodiment, the reaction includes reacting in a constant - temperature water - bath shaking table, the rotation speed of the shaking table is 150 - 240 r / min, such as 160 r / min, 180 r / min, 200 r / min, 230 r / min, etc.; the reaction temperature is from room temperature to 100 °C, such as 25 °C, 40 °C, 58 °C, 75 °C, 99 °C, etc.; the reaction time is 2 - 60 min, such as 2 min, 10 min, 28 min, 35 min, 59 min, etc.

[0034] Among them, too low a reaction temperature and too short a reaction time are not conducive to the dissolution of calcium sulfate dihydrate, while too high a reaction temperature and too long a reaction time will increase the reaction cost. Therefore, the above - mentioned reaction time and reaction temperature.

[0035] S3. Perform solid - liquid separation on the mixed solution to obtain a first filtrate.

[0036] In this embodiment, the solid - liquid separation in step S3 also obtains a filter cake, which is washed, dried, and used for subsequent resource utilization research. For example, through chemical composition analysis, it can be used as a raw material in the building materials field.

[0037] S4. Age the first filtrate and then separate out the filter cake.

[0038] In this embodiment, the aging temperature is 6 - 10 °C, such as 6 °C, 7 °C, 8 °C, 9 °C, etc.; the aging time is 12 - 40 h, such as 12.5 h, 15 h, 22.5 h, 30 h, 39 h, etc.

[0039] Among them, too low an aging temperature results in a low rate of combination of calcium ions and sulfate ions in the system, which is not conducive to the recrystallization of calcium sulfate dihydrate; too high an aging temperature increases the solubility of calcium sulfate dihydrate, thus reducing the precipitation amount of calcium sulfate dihydrate powder. Too short an aging time is not conducive to the precipitation of calcium sulfate dihydrate powder, and too long an aging time leads to an increase in cost. Therefore, the above aging time and aging temperature are selected.

[0040] In this embodiment, a second filtrate is also separated in step S4, and the method further includes using the second filtrate to replace all or part of the ammonium chloride solution in step S2.

[0041] S5. Wash the filter cake and obtain high-purity calcium sulfate dihydrate powder after drying. Among them, the phase of the high-purity calcium sulfate dihydrate powder is the gypsum phase, with a content greater than 99% and a whiteness greater than 90.

[0042] In this embodiment, the microscopic morphology of the high-purity calcium sulfate dihydrate powder includes granular and / or plate-like.

[0043] In this embodiment, the drying temperature in step S5 does not exceed 40°C, such as 15°C, 22°C, 25°C, 34°C, and 40°C, etc.; the drying can remove the adsorbed water on the surface of the calcium sulfate dihydrate powder.

[0044] Among them, when steps S1 - S5 are repeated until the soluble salts in the filtrate are supersaturated, ammonium chloride and ammonium sulfate in the filtrate are recovered; then the pH value is adjusted by adding ammonia water to precipitate and separate the enriched manganese ions in the filtrate in the form of manganese hydroxide, obtaining a third filtrate, and the third filtrate is used to prepare the ammonium chloride solution in step S2, such as replacing water to prepare the ammonium chloride solution.

[0045] To better understand the above exemplary embodiments of the present invention, the following further illustrates them with specific examples.

[0046] Example 1

[0047] Take a certain amount of electrolytic manganese slag sample, dry it at 40°C, grind it, and pass it through an 80-mesh sieve to obtain an electrolytic manganese slag powder sample; take 100 g of the electrolytic manganese slag powder sample and place it in a 5000 mL conical flask, add 3000 mL of 4 mol / L ammonium chloride solution to the conical flask, place the conical flask in a shaker, with the shaker speed of 200 r / min, react at 60°C for 30 min, then filter to obtain the first filtrate, wash the filter cake and dry it at 80°C, and it can be used as a raw material in the building materials field through chemical composition analysis.

[0048] Take 2000 mL of the above Ca 2+The leaching solution, i.e., the first filtrate, was poured into a 5000 mL beaker. The beaker was placed in a reactor, and the temperature of the reactor was controlled by a high and low temperature integrated machine. After aging at 8 °C for 30 hours, filtration was carried out to obtain a filter cake. The filter cake was washed and then dried at 40 °C to obtain high-purity calcium sulfate dihydrate powder. The whiteness of the obtained powder was 93.3, and the purity of the powder was 99.22%.

[0049] XRD test was carried out on the obtained high-purity calcium sulfate dihydrate powder, and the results were as Figure 1 shown. It can be seen from Figure 1 that the phase of the obtained powder is the gypsum phase, and the diffraction peaks of gypsum are relatively sharp, indicating that the crystallization degree of gypsum crystals in the sample is good; no diffraction peaks of other crystals were found except gypsum, indicating that the purity of the product is relatively high and its phase is the only gypsum phase.

[0050] Scanning electron microscopy test was carried out on the obtained high-purity calcium sulfate dihydrate powder, and the SEM image as Figure 2 shown was obtained. It can be seen from Figure 2 that the microscopic morphology of the obtained powder is plate-like and granular.

[0051] Example 2

[0052] A certain amount of electrolytic manganese slag sample was taken. After drying at 40 °C, it was ground and passed through an 80-mesh sieve to obtain an electrolytic manganese slag powder sample; 80 g of the electrolytic manganese slag powder sample was placed in a 5000 mL conical flask, 3200 mL of 2.5 mol / L ammonium chloride solution was added to the conical flask, and the conical flask was placed in a shaker. The shaker speed was 200 r / min. After reacting at 90 °C for 25 min, filtration was carried out to obtain the first filtrate.

[0053] Take 2500 mL of the above-mentioned Ca 2+ leaching solution, i.e., the first filtrate, was poured into a 5000 mL beaker. The beaker was placed in a reactor, and the temperature of the reactor was controlled by a high and low temperature integrated machine. After aging at 9 °C for 35 hours, filtration was carried out to obtain a filter cake. The filter cake was washed and then dried at 40 °C to obtain high-purity calcium sulfate dihydrate powder. The phase of the obtained powder is gypsum, the microscopic morphology is granular, the whiteness of the obtained powder is 94.5, and the purity of the powder is 99.48%.

[0054] Although the present invention has been described above in conjunction with exemplary embodiments and the accompanying drawings, those of ordinary skill in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag, characterized in that, The preparation method includes: (1) drying the electrolytic manganese residue and making it into electrolytic manganese residue powder; (2) mixing the electrolytic manganese residue powder with ammonium chloride solution, and obtaining a mixed solution after reaction; (3) performing solid-liquid separation on the mixed solution to obtain a first filtrate; (4) aging the first filtrate and separating out the filter cake; (5) washing the filter cake, and drying it to obtain high-purity calcium sulfate dihydrate powder, wherein the phase of the high-purity calcium sulfate dihydrate powder is gypsum phase, the content is greater than 99%, and the whiteness is greater than 90.

2. The method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag according to claim 1, wherein The concentration of the ammonium chloride solution is 1-5 mol / L; the ratio of the ammonium chloride solution to the electrolytic manganese residue powder is 25-50 mL / g.

3. The method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag according to claim 1, characterized in that, In step (2), the reaction includes reacting in a constant-temperature water bath shaking table, the rotation speed of the shaking table is 150-240 r / min, the reaction temperature is from room temperature to 100 °C, and the reaction time is 2-60 min.

4. The method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag according to claim 1, characterized in that, The temperature of the aging is 6-10 °C, and the time of the aging is 12-40 h.

5. A method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag according to claim 1, characterized in that, In step (1), the electrolytic manganese residue powder can pass through a 80-mesh sieve, and the drying includes drying by baking, and the baking temperature does not exceed 40 °C.

6. The method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese residue according to claim 1, characterized in that, In step (5), the drying temperature does not exceed 40 °C, and it is dried until the adsorbed water on the surface of the calcium sulfate dihydrate powder is removed.

7. A method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese slag according to claim 1, characterized in that, In step (4), a second filtrate is also separated out, and the method further includes using the second filtrate to replace all or part of the ammonium chloride solution in step (2).

8. A method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese residue according to claim 7, characterized in that, When repeating steps (1)-(5) until the soluble salts in the filtrate are supersaturated, ammonium chloride and ammonium sulfate in the filtrate are recovered; then the pH value is adjusted by adding ammonia water so that the enriched manganese ions in the filtrate precipitate and are separated in the form of manganese hydroxide, obtaining a third filtrate, and the third filtrate can be used to prepare the ammonium chloride solution described in step (2).

9. The method for preparing high-purity calcium sulfate dihydrate powder from electrolytic manganese residue according to claim 1, wherein The microscopic morphology of the high-purity calcium sulfate dihydrate powder includes granular and / or plate-like.

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