A method for purifying a crystalline potassium sulfate salt mineral

Abstract

The application discloses a purification method of crystalline potassium sulfate salt minerals, which comprises the following steps: drying and removing crystal water from the crystalline potassium sulfate salt, and then performing grinding treatment on the potassium sulfate salt; stirring and slurry-making the fine powder obtained in the grinding treatment at constant temperature by using brine; and performing flotation separation on the slurry obtained in the step of stirring and slurry-making by using sodium dodecyl sulfonate as a collecting agent and sodium hexametaphosphate as an inhibitor, so as to obtain a potassium sulfate salt concentrate. The method is green, energy-saving, consumption-reducing and high-efficient, qualified commercial-grade potassium sulfate salt can be obtained, and the crystalline potassium sulfate salt mineral resources can be fully utilized.

Description

Technical Field

[0001] The present invention relates to a method for purifying crystalline potassium sulfate minerals, and in particular to a method for purifying crystalline potassium sulfate minerals based on a combination of drying and dehydration, ball milling, and flotation separation, belonging to the technical field of mineral processing. Background Art

[0002] Crystalline sulfate has certain particularities compared to other minerals. Due to the high solubility of soluble salts, their flotation must be carried out in a saturated solution, which makes the selection and use of potassium sulfate separation technology very difficult. The current potassium salt extraction method is mainly the sun drying method, but this method cannot remove the sodium salt contained in the potassium salt, and there are also salt field parts and salt field mixed salt chemical processing parts. The existing potassium salt magnesium alum processing method for preparing potassium sulfate is to firstly evaporating the potassium sulfate with K under a certain evaporation time and brine concentration. + 、Na + Mg 2+ Based on the metastable phase diagram of the five-element water-salt system, when the mixed brine components are adjusted and enter the potassium salt magnesium sulfate crystallization area of ​​the five-element system, the K + It is mainly precipitated in the form of kainite, and the amount of precipitation of carnallite and sodium chloride is also controlled to a minimum. In the evaporation process of the mixed brine, two different grades of kainite can be obtained. The kainite with a higher sodium chloride content (NaCl content ≈ 30%) is precipitated first, and it can be used as a raw material for producing potassium sulfate after flotation and sodium removal; the higher grade kainite (NaCl content < 20%) is precipitated later. After the solid phase is precipitated, the mother liquor enters the winter cooling and further precipitates carnallite in the salt field. The precipitated carnallite solid phase is further reacted with the kainite mother liquor to obtain kainite, and the mother liquor can be reused. The above method is complicated and costly, which is not conducive to the vigorous development of industrial applications. A purification method for crystalline potassium sulfate minerals needs to be developed and utilized. Summary of the Invention

[0003] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for purifying crystalline potassium sulfate minerals, which can effectively improve the grade of crystalline potassium sulfate minerals to obtain commercial-grade potassium sulfate with a high recovery rate, thereby achieving full utilization of crystalline potassium sulfate mineral resources. The method is green, environmentally friendly, energy-saving, simple and efficient, and is conducive to large-scale promotion and application.

[0004] In order to achieve the above technical objectives, the present invention provides a method for purifying crystalline potassium sulfate minerals. The method comprises the following steps: drying the crystalline potassium sulfate to remove crystal water and then grinding the ore; stirring the fine powder obtained by grinding with brine at a constant temperature to prepare a slurry; and flotation separation of the obtained slurry using sodium dodecyl sulfate as a collector and sodium hexametaphosphate as a depressant to obtain a potassium sulfate concentrate.

[0005] The technical solution of the present invention mainly includes the processes such as drying, grinding, screening, flotation separation for the purification process of crystalline potassium sulfate mineral, can effectively improve the grade of crystalline potassium sulfate mineral, to obtain commercial grade potassium sulfate, and the recovery is high, realizes the full utilization of crystalline potassium sulfate mineral resources. First, by drying process, the main purpose is to fully remove the crystal water in crystalline potassium sulfate mineral, avoid the adhesion effect brought by crystalline potassium sulfate mineral crystal water, be conducive to the full dispersion and dissociation of the mineral in the grinding stage, be unlikely to adhere to the ball mill wall, thus effectively improve the fineness of potassium sulfate. Secondly, in the flotation process, select suitable flotation reagent, sodium lauryl sulfate and sodium hexametaphosphate inhibitor are used in combination, not only can effectively improve the grade and recovery of potassium sulfate concentrate, and by reducing the surface tension of solution and the critical micelle concentration of collector, improve the activity of reagent, effectively avoid the shortcomings such as amine agent foam is sticky, defoaming difficulty, improve flotation separation effect, reduce foam amount, solve the flotation process foam delivery problem. In summary, commercial-grade potassium sulfate can be obtained through the above process, and the recovery rate of potassium sulfate is high.

[0006] As a preferred solution, the drying conditions are: a temperature of 105-110°C and a time of 1-3 hours. Drying is preferably performed at a temperature above 100°C for a sufficient time to effectively remove the crystallization water. If the temperature is too low or the time is too short, only the free water adsorbed on the surface of the potassium sulfate can be removed. Removal of the crystallization water can avoid the adhesion effect caused by the crystallization water of the crystalline potassium sulfate mineral, allowing the potassium sulfate to be fully dispersed and dissociated, thereby effectively improving the grade and recovery rate of the potassium sulfate concentrate.

[0007] As a preferred solution, the grinding process conditions are: a ball mill speed of 300-500 r / min, a ball-to-material ratio of 2-5:1, and a grinding time of 3-8 minutes. Dry grinding is employed. By controlling the grinding conditions, the crystalline potassium sulfate mineral can be ground to an appropriate particle size, facilitating subsequent flotation separation.

[0008] As a preferred solution, the fine powder obtained from the grinding process is screened. The -200- to +400-mesh fine powder is used for flotation separation, the -400-mesh fine powder is used to prepare brine, and the +200-mesh fine powder is regrinded. The most suitable particle size for flotation separation is between -200 and +400 mesh. The smaller particle size of the crystalline potassium sulfate mineral is used to prepare the brine for flotation, while the larger particle size of the crystalline potassium sulfate mineral is regrinded.

[0009] As a preferred solution, the mass percentage concentration of the slurry is 18-25%. The preferred slurry concentration is beneficial to the flotation process. If the concentration is too low, it is not conducive to flotation recovery. If the concentration is too high, it will cause potassium sulfate to recrystallize and block the flotation machine. Therefore, controlling the slurry concentration within the preferred range is beneficial to the dispersion of the slurry and avoids potassium sulfate recrystallization and blockage of the flotation machine.

[0010] As a preferred solution, the constant temperature stirring slurrying process is as follows: potassium sulfate is added to brine and mechanically stirred for 20 to 40 minutes at a constant temperature of 25 to 30°C. Placing crystalline potassium sulfate mineral in brine and using a saturated potassium sulfate solution as a medium can prevent its dissolution, which can lead to problems such as low recovery rate and low grade. Constant temperature mechanical stirring can enhance its full dispersion, thereby preventing potassium sulfate recrystallization and clogging of the flotation machine.

[0011] As a preferred embodiment, the flotation separation includes a roughing process and a fine separation process. As a more preferred embodiment, the roughing process uses 80-120 g / t of sodium dodecyl sulfate and 40-60 g / t of sodium hexametaphosphate inhibitor; the fine separation process is a blank fine separation process. The present invention utilizes a roughing and fine separation process to achieve flotation separation of crystalline potassium sulfate salts. The sodium dodecyl sulfate collector and the sodium hexametaphosphate inhibitor are used as flotation reagents during the flotation process. The sodium dodecyl sulfate collector has a selective affinity for the surface of crystalline potassium sulfate minerals, while the sodium hexametaphosphate inhibitor acts as a dispersant, reducing the surface tension of the solution and the critical micelle concentration of the sodium dodecyl sulfate collector, improving the activity of the reagents. This effectively avoids the shortcomings of existing amine collectors, such as sticky foam and difficulty in defoaming. It improves flotation separation efficiency, reduces foam volume, and solves the problem of foam transport during the flotation process. The combined use of the sodium dodecyl sulfate collector and the sodium hexametaphosphate inhibitor can effectively improve the grade and recovery rate of potassium sulfate concentrate.

[0012] As a preferred solution, the potassium sulfate concentrate is washed with brine and then dried. Using brine to wash the potassium sulfate concentrate can avoid dissolution loss of the potassium sulfate concentrate and reduce the recovery rate.

[0013] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0014] (1) The present invention adopts a purification process including drying, grinding, screening, flotation separation, etc., which can not only avoid the adhesion effect caused by the crystal water of crystalline potassium sulfate minerals and fully disperse and dissociate the potassium sulfate, but also effectively improve the grade and recovery rate of potassium sulfate concentrate by using special flotation separation agents.

[0015] (2) The present invention adopts brine slurry preparation and ensures that potassium sulfate minerals are fully dispersed under the action of constant temperature mechanical stirring, thereby avoiding the problem of potassium sulfate recrystallization when encountering brine.

[0016] (3) The present invention uses a sodium dodecylsulfonate collector and a sodium hexametaphosphate inhibitor in combination, which can reduce the surface tension of the solution and the critical micelle concentration of the collector, improve the activity of the agent, avoid the technical disadvantages of the prior art using a single amine collector, and improve the selectivity and collection capacity of the combined agent for potassium sulfate and the inhibitory effect on gangue minerals.

[0017] (4) The method of the present invention can greatly improve the recovery efficiency of potassium sulfate, and has a simple process, low cost, and is suitable for industrial application. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with specific preferred embodiments, but the scope of protection of the claims of the present invention is not limited thereby.

[0019] The materials and instruments used in the following examples are all commercially available.

[0020] The sodium sulfate potash mine used in the embodiment of the present invention is a salt lake mineral resource in Hunan Province. The main minerals are sodium sulfate and potassium sulfate, among which the mass percentage of potassium sulfate is 36%, the mass percentage of sodium sulfate is 60%, and the rest are other impurities.

[0021] Example 1

[0022] The following is a process for improving the quality and reducing impurities of crystalline potassium sulfate minerals, which specifically includes the following steps:

[0023] (1) Drying the crystalline potassium sulfate mineral, specifically: placing the crystalline potassium sulfate in an oven, setting the temperature to 108° C., and drying for 2 hours to completely remove the crystal water.

[0024] (2) Grinding the potassium sulfate salt after completely removing the crystal water, specifically: placing the sulfate in a drum ball mill, the ball mill speed is 400 r / min, the ball-to-material ratio is 3:1, and the grinding is performed for 5 minutes to obtain a fineness of -200 mesh to +400 mesh (-0.074 mm to +0.038 mm) accounting for 98 wt%.

[0025] (3) Screening the ground potassium sulfate salt, specifically: placing the ground potassium sulfate salt on 200 mesh and 400 mesh sieves, screening to obtain potassium sulfate salt with a size of -200 mesh to +400 mesh (-0.074 mm to +0.038 mm), returning the product on the sieve to be ground again, and using the product under the sieve to make brine.

[0026] (4) Flotation separation, filtration, drying and purification, specifically: -200 mesh to +400 mesh (-0.074mm to +0.038mm) potassium sulfate salt is placed in brine, mechanically stirred at a constant temperature of 28±1℃ for 30 minutes to fully disperse it, and the concentration is controlled at 20%, and a 1 coarse and 1 fine flotation process is performed to separate the -200 to +400 mesh potassium sulfate salt. 100g / t of sodium dodecyl sulfate and 50g / t of sodium hexametaphosphate inhibitor are added in the roughing process for 3 minutes. The fine separation is performed as a blank scraping foam to obtain a concentrate product, potassium sulfate concentrate K, middlings m and tailings X. After flotation, the concentrate is filtered to obtain a concentrate product. Brine is required in the whole process. Finally, the final concentrate product is obtained by drying after filtration. The process is kept at a constant temperature of 108℃ for 1 hour to obtain a high-grade potassium sulfate salt final concentrate product. According to the above process, the crystalline potassium sulfate salt (the average mass percentage of potassium sulfate in these raw ores is 36%) was purified and reduced in impurities many times, and the average recovery results are shown in Table 1.

[0027] Table 1 Experimental results of Example 1

[0028]

[0029] As shown in Table 1, in Example 1, after treatment by the process of the present invention, the grade of potassium sulfate in the obtained potassium sulfate concentrate was increased to 88.6%, and the recovery rate was 92.3%. Obviously, the mineral processing process of the present invention can separate and purify potassium sulfate from crystalline potassium sulfate salt ore, which can achieve effective resource recovery and has broad practical significance for improving the comprehensive utilization rate of potassium sulfate resources.

[0030] Example 2

[0031] The following is a process for improving the quality and reducing impurities of crystalline potassium sulfate minerals, which specifically includes the following steps:

[0032] (1) Drying the crystalline potassium sulfate mineral, specifically: placing the crystalline potassium sulfate in an oven, setting the temperature to 108° C., and drying for 2 hours to completely remove the crystal water.

[0033] (2) Grinding the potassium sulfate salt after completely removing the crystal water, specifically: placing the sulfate in a drum ball mill, the ball mill speed is 450r / min, the ball-to-material ratio is 4:1, and the grinding is performed for 4 minutes to obtain a fineness of -200 mesh to +400 mesh (-0.074mm to +0.038mm) accounting for 97wt%.

[0034] (3) Screening the ground potassium sulfate salt, specifically: placing the ground potassium sulfate salt on 200 mesh and 400 mesh sieves, screening to obtain potassium sulfate salt with a size of -200 mesh to +400 mesh (-0.074 mm to +0.038 mm), returning the product on the sieve to be ground again, and using the product under the sieve to make brine.

[0035] (4) Flotation separation, filtration, drying and purification, specifically: -200 mesh to +400 mesh (-0.074mm to +0.038mm) potassium sulfate salt is placed in brine, mechanically stirred at a constant temperature of 28±1℃ for 30 minutes to fully disperse it, and the concentration is controlled at 22%, and a 1 coarse and 1 fine flotation process is performed to separate the -200 to +400 mesh potassium sulfate salt. 100g / t of sodium dodecyl sulfate and 50g / t of sodium hexametaphosphate inhibitor are added in the rough selection for 3 minutes, and the fine selection is performed as a blank scraping foam to obtain a concentrate product, potassium sulfate concentrate K, middlings m and tailings X. After flotation, the concentrate is filtered to obtain a concentrate product. Brine is required in the whole process. Finally, the final concentrate product is obtained by filtration and drying. The process is kept at a constant temperature of 108℃ for 1 hour to obtain a high-grade potassium sulfate salt final concentrate product. According to the above process, the crystalline potassium sulfate salt (the average mass percentage of potassium sulfate in these raw ores is 36%) was purified and reduced for impurities many times, and the average recovery results are shown in Table 2.

[0036] Table 2 Experimental results of Example 2

[0037]

[0038] As shown in Table 2, in Example 2, after treatment by the process of the present invention, the grade of potassium sulfate in the obtained potassium sulfate concentrate was increased to 85.6%, and the recovery rate was 90.3%. Obviously, the mineral processing process of the present invention can separate and purify potassium sulfate from crystalline potassium sulfate salt ore, can achieve effective resource recovery, and has broad practical significance for improving the comprehensive utilization rate of potassium sulfate resources.

[0039] Comparative Example 1

[0040] The following is a process for improving the quality and reducing impurities of crystalline potassium sulfate minerals, which specifically includes the following steps:

[0041] (1) Drying the crystalline potassium sulfate mineral, specifically: placing the crystalline potassium sulfate in an oven, setting the temperature to 108° C., and drying for 2 hours to completely remove the crystal water.

[0042] (2) Grinding the potassium sulfate salt after completely removing the crystal water, specifically: placing the sulfate in a drum ball mill, the ball mill speed is 400 r / min, the ball-to-material ratio is 3:1, and the grinding is performed for 5 minutes to obtain a fineness of -200 mesh to +400 mesh (-0.074 mm + 0.038 mm) accounting for 98 wt%.

[0043] (3) Screening the ground potassium sulfate salt, specifically: placing the ground potassium sulfate salt on 200 mesh and 400 mesh sieves, screening to obtain potassium sulfate salt with a size of -200 mesh to +400 mesh (-0.074 mm to +0.038 mm), returning the product on the sieve to be ground again, and using the product under the sieve to make brine.

[0044] (4) Flotation separation, filtration, drying and purification, specifically: -200 mesh to +400 mesh (-0.074mm to +0.038mm) potassium sulfate salt is placed in brine, mechanically stirred at room temperature of 15℃ for 30 minutes to fully disperse it, and the concentration is controlled at 20%, and a 1 coarse and 1 fine flotation process is performed to separate -200 to +400 mesh (-0.074mm to +0.038mm) potassium sulfate salt by flotation. 100g / t of sodium dodecyl sulfate and 50g / t of sodium hexametaphosphate inhibitor are added in the coarse separation for 3 minutes, and the fine separation is performed as blank scraping foam to obtain a concentrate product, potassium sulfate concentrate K, middlings m and tailings X. After flotation, the concentrate is filtered to obtain a concentrate product. Brine is required in the whole process. Finally, the final concentrate product is obtained by drying after filtration. The process is kept at a constant temperature of 108℃ for 1 hour to obtain a high-grade potassium sulfate salt final concentrate product. According to the above process, the crystalline potassium sulfate salt (the average mass percentage of potassium sulfate in these raw ores is 36%) was purified and reduced for impurities many times, and the average recovery results are shown in Table 2.

[0045] Table 3 Comparative Example 1 Test Results

[0046]

[0047] As shown in Table 2, in Comparative Example 1, when the dispersion was not heated, the grade of potassium sulfate in the potassium sulfate concentrate was 48.2%, and the recovery rate was 56.3%. Obviously, the effect was not as good as that of Example 1.

[0048] Comparative Example 2

[0049] The following is a process for improving the quality and reducing impurities of crystalline potassium sulfate minerals, which specifically includes the following steps:

[0050] (1) The crystalline potassium sulfate mineral is not dried.

[0051] (2) The potassium sulfate salt is directly ground, specifically: the sulfate is placed in a drum ball mill, the ball mill speed is 400 r / min, the ball-to-material ratio is 3:1, and the grinding is performed for 5 minutes to obtain a fineness of -200 mesh to +400 mesh (-0.074 mm + 0.038 mm) accounting for 50 wt%.

[0052] (3) Screening the ground potassium sulfate salt, specifically: placing the ground potassium sulfate salt on 200 mesh and 400 mesh sieves, screening to obtain potassium sulfate salt with a size of -200 mesh to +400 mesh (-0.074 mm + 0.038 mm), returning the product on the sieve to be ground again, and using the product under the sieve to make brine.

[0053] (4) Flotation separation, filtration, drying and purification, specifically: -200 mesh to +400 mesh (-0.074mm + 0.038mm) potassium sulfate salt is placed in brine, mechanically stirred at a constant temperature of 28 ± 1 ° C for 30 minutes to fully disperse it, and the concentration is controlled at 20%, and a 1 coarse and 1 fine flotation process is performed to separate -200 to +400 mesh (-0.074mm + 0.038mm) potassium sulfate salt by flotation. 100g / t of sodium dodecyl sulfate and 50g / t of sodium hexametaphosphate inhibitor are added in the rough selection for 3 minutes. The fine selection is performed as a blank scraping foam to obtain a concentrate product, potassium sulfate concentrate K, middlings m and tailings X. After flotation, the concentrate is filtered to obtain a concentrate product. Brine is required in the whole process. Finally, the final concentrate product is obtained by drying after filtration. The process is kept at a constant temperature of 108 ° C and lasts for 1 hour to obtain a high-grade potassium sulfate salt final concentrate product. According to the above process, the crystalline potassium sulfate salt (the average mass percentage of potassium sulfate in these raw ores is 36%) was purified and reduced for impurities many times, and the average recovery results are shown in Table 4.

[0054] Table 4 Comparative Example 2 Test Results

[0055]

[0056] As shown in Table 4, in Comparative Example 2, when the crystalline potassium sulfate mineral was not dried, the potassium sulfate grade in the obtained potassium sulfate concentrate was 56.3% and the recovery rate was 70.2%. Obviously, the effect was not as good as that of Example 1.

[0057] Comparative Example 3

[0058] The following is a process for improving the quality and reducing impurities of crystalline potassium sulfate minerals, which specifically includes the following steps:

[0059] (1) Drying the crystalline potassium sulfate mineral, specifically: placing the crystalline potassium sulfate in an oven, setting the temperature to 108° C., and drying for 2 hours to completely remove the crystal water.

[0060] (2) Grinding the potassium sulfate salt after completely removing the crystal water, specifically: placing the sulfate in a drum ball mill, the ball mill speed is 400 r / min, the ball-to-material ratio is 3:1, and the grinding is performed for 5 minutes to obtain a fineness of -200 mesh to +400 mesh (-0.074 mm + 0.038 mm) accounting for 98 wt%.

[0061] (3) Screening the ground potassium sulfate salt, specifically: placing the ground potassium sulfate salt on 200 mesh and 400 mesh sieves, screening to obtain potassium sulfate salt with a size of -200 mesh to +400 mesh (-0.074 mm + 0.038 mm), returning the product on the sieve to be ground again, and using the product under the sieve to make brine.

[0062] (4) Flotation separation, filtration, drying and purification, specifically: -200 mesh to +400 mesh (-0.074mm + 0.038mm) potassium sulfate salt is placed in brine, mechanically stirred at a constant temperature of 28 ± 1 ° C for 30 minutes to fully disperse it, and the concentration is controlled at 30%, and a 1 coarse and 1 fine flotation process is performed to separate -200 to +400 mesh (-0.074mm + 0.038mm) potassium sulfate salt by flotation. 100g / t of sodium dodecyl sulfate and 50g / t of sodium hexametaphosphate inhibitor are added in the rough selection for 3 minutes. The fine selection is performed as a blank scraping foam to obtain a concentrate product, potassium sulfate concentrate K, middlings m and tailings X. After flotation, the concentrate is filtered to obtain a concentrate product. Brine is required in the whole process. Finally, the final concentrate product is obtained by drying after filtration. The process is kept at a constant temperature of 108 ° C and lasts for 1 hour to obtain a high-grade potassium sulfate salt final concentrate product. According to the above process, the crystalline potassium sulfate salt (the average mass percentage of potassium sulfate in these raw ores is 36%) was purified and reduced in impurities many times, and the average recovery results are shown in Table 5.

[0063] Table 5 Test results of comparative example 3

[0064]

[0065] As shown in Table 5, in Comparative Example 3, when the slurry concentration was adjusted to be too high, the grade of potassium sulfate in the obtained potassium sulfate concentrate was 52.0%, and the recovery rate was 65.3%. Obviously, the effect was not as good as that of Example 1.

[0066] Comparative Example 4

[0067] The following is a process for improving the quality and reducing impurities of crystalline potassium sulfate minerals, which specifically includes the following steps:

[0068] (1) Drying the crystalline potassium sulfate mineral, specifically: placing the crystalline potassium sulfate in an oven, setting the temperature to 108° C., and drying for 2 hours to completely remove the crystal water.

[0069] (2) Grinding the potassium sulfate salt after completely removing the crystal water, specifically: placing the sulfate in a drum ball mill, the ball mill speed is 400 r / min, the ball-to-material ratio is 3:1, and the grinding is performed for 5 minutes to obtain a fineness of -200 mesh to +400 mesh (-0.074 mm + 0.038 mm) accounting for 98 wt%.

[0070] (3) Screening the ground potassium sulfate salt, specifically: placing the ground potassium sulfate salt on 200 mesh and 400 mesh sieves, screening to obtain potassium sulfate salt with a size of -200 mesh to +400 mesh (-0.074 mm + 0.038 mm), returning the product on the sieve to be ground again, and using the product under the sieve to make brine.

[0071] (4) Flotation separation, filtration, drying and purification, specifically: -200 mesh to +400 mesh (-0.074mm + 0.038mm) potassium sulfate salt is placed in brine, mechanically stirred at a constant temperature of 28 ± 1 ° C for 30 minutes to fully disperse it, and the concentration is controlled at 20%, and a 1 coarse and 1 fine flotation process is performed to separate -200 to +400 mesh (-0.074mm + 0.038mm) potassium sulfate salt by flotation. 100g / t of sodium dodecyl sulfate is added to the coarse selection without using inhibitors for 3 minutes. The fine selection is performed as a blank scraping foam to obtain a concentrate product, potassium sulfate concentrate K, middlings m and tailings X. After flotation, the concentrate is filtered to obtain a concentrate product. Brine is required in the whole process. Finally, the final concentrate product is obtained by drying after filtration. The process is kept at a constant temperature of 108 ° C and lasts for 1 hour to obtain a high-grade potassium sulfate salt final concentrate product. According to the above process, the crystalline potassium sulfate salt (the average mass percentage of potassium sulfate in these raw ores is 36%) was purified and reduced in impurities many times, and the average recovery results are shown in Table 6.

[0072] Table 6 Test results of Comparative Example 4

[0073]

[0074] As shown in Table 5, in Comparative Example 4, when no inhibitor was used, the grade of potassium sulfate in the potassium sulfate concentrate obtained was 51.33%, and the recovery rate was 62.8%. Obviously, the effect was not as good as that of Example 1.

Claims

1. A method for purifying a crystalline potassium sulfate mineral, characterized in that: The crystalline potassium sulfate salt is dried to remove the crystal water and then ground. The fine powder obtained by grinding is stirred and slurried with brine at a constant temperature. The resulting slurry is then flotated and separated using sodium dodecyl sulfate as a collector and sodium hexametaphosphate as a depressant to obtain potassium sulfate salt concentrate.

2. The method for purifying a crystalline potassium sulfate mineral according to claim 1, wherein: The drying conditions are: temperature of 105-110° C. and time of 1-3 hours.

3. The method for purifying a crystalline potassium sulfate mineral according to claim 1, wherein: The grinding treatment conditions are: ball mill speed of 300-500 r / min, ball-to-material ratio of 2-5:1, and grinding time of 3-8 min.

4. The method for purifying a crystalline potassium sulfate mineral according to claim 1, wherein: The fine powder obtained from the grinding process is sieved, the fine powder of -200 mesh to +400 mesh is used for flotation separation, the fine powder of -400 mesh is used for preparing brine, and the fine powder of +200 mesh is regrinded.

5. The method for purifying a crystalline potassium sulfate mineral according to claim 1, wherein: The mass percentage concentration of the slurry is 18-25%.

6. The method for purifying a crystalline potassium sulfate mineral according to claim 1, wherein: The process of constant temperature stirring and slurry preparation is as follows: potassium sulfate is added into brine, and mechanically stirred for 20 to 40 minutes at a constant temperature of 25 to 30°C.

7. The method for purifying a crystalline potassium sulfate mineral according to claim 1, wherein: The flotation separation includes a roughing separation and a cleaning separation; The reagent system of the rough selection is: 80-120 g / t of sodium dodecyl sulfate and 40-60 g / t of sodium hexametaphosphate inhibitor; the fine selection is blank fine selection.

8. The method for purifying a crystalline potassium sulfate mineral according to claim 1, wherein: The potassium sulfate concentrate is washed with brine and then dried.

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