A green and efficient decolorization and upgrading method of phosphogypsum

Abstract

The application discloses a green and efficient decoloring and upgrading method for phosphogypsum, and comprises the following steps: grinding and ore dressing, micro-bubble pretreatment, one-stage rough reverse flotation, one-stage fine reverse flotation, two-stage fine reverse flotation and drying, wherein the mixed collector is a combination of emulsifier OP-10 and tetradecyl trimethyl ammonium chloride. The application comprehensively adopts the grinding and ore dressing, the micro-bubble pretreatment, the one-stage rough reverse flotation, the one-stage fine reverse flotation and the two-stage fine reverse flotation, adjusts the types and dosages of the mixed collectors, realizes the purpose of floating various impurities in different types of phosphogypsum in the reverse flotation system, and has the advantages of simple phosphogypsum impurity removal process, small reagent dosage, low cost, low process energy consumption and avoidance of pollution problems caused by direct storage of the phosphogypsum.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of phosphogypsum decolorization and impurity removal, and particularly relates to a green and efficient decolorization and quality improvement method for phosphogypsum. BACKGROUND

[0002] Phosphogypsum is a solid waste produced in the wet-process phosphoric acid process, and its main chemical components are CaSO4·2H2O and CaSO4·1 / 2H2O. When phosphoric acid is produced by using the wet-process, the amount of phosphogypsum produced is about 4-5 times that of phosphoric acid. As an industrial solid waste, if phosphogypsum is not disposed for a long time, it will cause a series of environmental safety problems. Compared with general gypsum, the impurity content in phosphogypsum is high, such as phosphoric acid and its salt impurities, fluoride impurities, organic impurities, SiO2, and part of heavy metal ions, radioactive elements, etc. Therefore, the water resistance, whiteness, hardness and other aspects of phosphogypsum are not as good as those of gypsum, which greatly limits its application field and makes it difficult to achieve resource utilization. In view of this hot issue, domestic and foreign enterprises have carried out long-term research, but this world problem has not been solved. The existing phosphogypsum technology is faced with problems such as high cost and heavy pollution. For example, the water washing method consumes a large amount of water resources, and the wastewater after water washing is still difficult to handle; the pyrometallurgical method is faced with problems such as high risk and high energy consumption.

[0003] Flotation, as a common and efficient separation method, has a wide range of applications and strong adaptability. It is often used in the beneficiation of various metallic and non-metallic minerals and is also widely used in other fields such as chemical engineering, building materials, and agriculture. However, there is currently limited research on flotation for the treatment of phosphogypsum. Compared with direct flotation, reverse flotation is a more technically reasonable method for desilication of phosphogypsum. It has a shorter flotation process, easier dewatering of the flotation product, and lower overall cost, making it more suitable for green and economical treatment of phosphogypsum. Currently, research on phosphogypsum flotation desilication focuses on reverse flotation desilication processes under strongly acidic environments. This process uses various ammonium salts and other collectors plus frothers for reverse flotation desilication, but it faces problems such as poor desilication effect, incomplete removal of organic matter, low grade of phosphogypsum product, and expensive reagents. For example, CN113695085A discloses a combined collector for decarbonizing phosphogypsum and its solution preparation method and application. This combined collector includes benzyl quaternary ammonium salt, non-polar oil, and / or alcohols. This reagent can achieve simultaneous desilication and decarbonization under strongly acidic conditions, increasing the whiteness of phosphogypsum concentrate from approximately 43% to a maximum of 56.2%, with a desilication rate of 22.3-46.6% and an increase in calcium sulfate dihydrate content of approximately 3 percentage points. CN102500469A discloses a reverse flotation process for desilication and impurity removal of phosphogypsum. By adding 1-15 kg / t of modifier (caustic soda, water glass, lime, hydrochloric acid, etc.) and 1-10 kg / t of collector (fatty acid collectors, amine collectors) to the phosphogypsum slurry, the silica content of phosphogypsum can be reduced from 8-13% to below 3% after one or two reverse flotation operations. However, it also has problems such as large reagent dosage, high reagent cost, and generally poor desilication selectivity.

[0004] In summary, there are still many problems in the current treatment of phosphogypsum waste. Therefore, providing a phosphogypsum decolorization method with low reagent consumption, higher cost, and better impurity removal effect is of great significance for solving the problem of solid waste and impurities in phosphogypsum. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a green and efficient decolorization and quality improvement method for phosphogypsum, solving the technical problems of difficult impurity removal, large amount of reagents, high cost, high energy consumption and serious pollution of phosphogypsum in the prior art.

[0006] A green and efficient method for decolorizing and upgrading phosphogypsum includes the following steps:

[0007] Grinding: The raw phosphogypsum ore is ball-milled;

[0008] Microbubble pretreatment: The ball-milled phosphogypsum is mixed with water to make phosphogypsum slurry, and then microbubble pretreatment is performed;

[0009] First-stage rough reverse flotation: Adjust the pH of the microbubble pretreated phosphogypsum slurry to 6.5-7.5, then heat it to 40-50℃, add the mixed collector and frother, stir and adjust the slurry, and carry out first-stage rough reverse flotation until the froth is white.

[0010] First stage of fine reverse flotation: Add the mixed collector and frother to the phosphogypsum slurry after the first stage of rough reverse flotation, stir and adjust the slurry, and then carry out a first stage of fine reverse flotation until the froth is white.

[0011] Second-stage fine reverse flotation: Add mixed collector and frother to the phosphogypsum slurry after the second-stage fine reverse flotation, stir and adjust the slurry, and then carry out the second-stage fine reverse flotation until the froth is white.

[0012] Drying: The phosphogypsum slurry after the second stage of fine reverse flotation is filtered and dried to obtain high-purity fine-grained dihydrate gypsum; wherein the mixed collector is a combination of emulsifier OP-10 and tetradecyltrimethylammonium chloride.

[0013] Compared with the prior art, the beneficial effects of the present invention include:

[0014] This invention comprehensively employs grinding, microbubble pretreatment, one-stage rough reverse flotation, one-stage fine reverse flotation, and two-stage fine reverse flotation, and adjusts the type and dosage of the mixed collector to achieve the purpose of floating various impurities in different types of phosphogypsum in the reverse flotation system. The phosphogypsum impurity removal process is simple, requires small reagent dosage, has low cost, low process energy consumption, and avoids the pollution problems caused by direct stockpiling of phosphogypsum. Attached Figure Description

[0015] Figure 1 The graph shows the effect of using 1431 and 1231 as collectors on the grade of phosphogypsum.

[0016] Figure 2 The graph shows the effect of using 1431 and 1231 as collectors on the whiteness of phosphogypsum.

[0017] Figure 3 This is a process flow diagram of one embodiment of the green and efficient decolorization and quality improvement method for phosphogypsum provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] This invention provides a green and efficient method for decolorizing and upgrading phosphogypsum, comprising the following steps:

[0020] S1. Grinding: Ball milling the raw phosphogypsum ore;

[0021] S2, microbubble pretreatment: the ball-milled phosphogypsum is added with water to prepare a phosphogypsum slurry, and then microbubble pretreatment is performed;

[0022] S3, one-stage rough reverse flotation: the phosphogypsum slurry after microbubble pretreatment is adjusted to pH 6.5-7.5, and then heated to 40-50℃, and then mixed collector and frother are added, and after stirring and slurry preparation, one-stage rough reverse flotation is performed, and the flotation is continued until the froth is white;

[0023] S4, one-stage fine reverse flotation: mixed collector and frother are added to the phosphogypsum slurry after one-stage rough reverse flotation, and after stirring and slurry preparation, one-stage fine reverse flotation is performed, and the flotation is continued until the froth is white;

[0024] S5, two-stage fine reverse flotation: mixed collector and frother are added to the phosphogypsum slurry after two-stage fine reverse flotation, and after stirring and slurry preparation, two-stage fine reverse flotation is performed, and the flotation is continued until the froth is white;

[0025] S6, drying: the phosphogypsum slurry after two-stage fine reverse flotation is subjected to suction filtration and drying to obtain high-purity fine-grained dihydrate gypsum. The mixed collector is a combination of emulsifier OP-10 and tetradecyl trimethyl ammonium chloride (hereinafter referred to as 1431).

[0026] The inventors found in previous experiments that under the conditions of single-factor experiment (without microbubble pretreatment, without emulsifier OP-10), 1431 and dodecyl trimethyl ammonium chloride (hereinafter referred to as 1231) both under their respective optimal pH conditions, 0.074 mm particle size content of about 60%, slurry concentration of 25%, and frother of methyl isobutyl carbinol under the same conditions for 3 minutes, the desilication and whitening effect of 1231-treated phosphogypsum was inferior to that of 1431 (see Figures 1-2 ). Moreover, 1231 is more expensive than 1431, and as a reverse flotation collector, 1431 exhibits more cost-effective collecting ability. As a cationic collector, 1431 has N + groups and long-chain methyl groups, and the N + groups can produce conventional physical adsorption with silicon-containing substances in phosphogypsum, and the methyl groups have hydrogen bonding action on the surface of silicon-containing impurities, and 1431 does not need to be acidified and has good water solubility.

[0027] Meanwhile, the emulsification of the collector helps to improve the dispersion effect of the reagent, form a micro-particle oil bead-shaped emulsion, increase the surface area of the reagent, increase the contact opportunity of the reagent and the mineral particles, thereby greatly reduce the dosage of the flotation reagent, shorten the flotation time, and improve the flotation efficiency. In addition, the active oil bubble formed by the emulsifier OP-10 can act on specific sites (hydrophobic and hydrophilic sites) on the surface of phosphogypsum, significantly improving the selectivity and adhesion strength of the reagent, and its collecting effect is realized by the electrostatic and hydrogen bond interaction between the phosphogypsum surface, the covering effect of the long chain of the reagent on the polar group of the phosphogypsum surface, and the synergistic effect with another collector 1431. 1431 has good compatibility with OP-10, and the two produce a synergistic effect in the flotation process, not only having good collecting effect on the silicon impurities in the phosphogypsum, but also having good adsorption effect on organic matter, further improving the whiteness and grade of the phosphogypsum. The preparation of the mixed collector of the present application does not require high temperature and high pressure, which can greatly simplify the reagent and save the cost of the reagent. Compared with the existing phosphogypsum mineral collector, the mixed collector has strong pH adaptability and is not affected by various impurities in the phosphogypsum, and the flotation foam is not sticky, easy to dissipate and settle.

[0028] In addition, the present application effectively increases the floatability of the phosphogypsum by adopting front-end grinding, effectively removes the soluble impurities in the phosphogypsum and increases the dispersity again by micro-bubble pretreatment, and selects the mixture of 1431 and emulsifier OP-10 as the collector for reverse flotation of silicon, which has strong pH adaptability and is not affected by various impurities in the phosphogypsum, and the flotation foam is not sticky, easy to dissipate and settle. It can be seen that the present application comprehensively adopts grinding, micro-bubble pretreatment, one-stage rough reverse flotation, one-stage fine reverse flotation, and two-stage fine reverse flotation, and adjusts the type and dosage of the mixed collector, so as to realize the purpose of floating various impurities in different types of phosphogypsum in the reverse flotation system. The phosphogypsum impurity removal process is simple, the reagent dosage is small, the cost is low, the process energy consumption is low, and the pollution problem caused by direct storage of the phosphogypsum is avoided.

[0029] In the present embodiment, a dispersant is also added in the ball milling process in step S1. By adding the dispersant, the present application can increase the grinding and flotation efficiency and reduce the energy consumption.

[0030] In some specific embodiments of the present application, the dispersant is sodium hexametaphosphate in step S1.

[0031] In some more specific embodiments of the present application, the dispersant accounts for 0.2%-0.8% of the mass of the phosphogypsum, and further 0.5% in step S1.

[0032] In the present embodiment, the particle size of the phosphogypsum after ball milling is 90% or more below 200 mesh in step S1.

[0033] In the embodiment, the concentration of the phosphogypsum ore slurry in step S2 is 20-40%, and further 25%.

[0034] In the embodiment, in step S2, an ultramicro bubble generator (bubble size less than 1 micron) is selected, the microbubble pretreatment temperature is 40-50°C, and the microbubble pretreatment time is 10-20 min.

[0035] In the embodiment, in step S3, the pH of the microbubble pretreated phosphogypsum ore slurry is adjusted to 6.8-7.2.

[0036] In the embodiment, in step S3, the pH adjusting agent used for adjusting the pH is at least one of sulfuric acid or calcium oxide.

[0037] In the embodiment, in the mixed collector, the mass ratio of 1431 to the emulsifier OP-10 is (1-9):1, including but not limited to 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc.

[0038] In the embodiment, the frother is methyl isobutyl carbinol (MIBC).

[0039] In the embodiment, in step S3, the amount of the mixed collector is 50-100 g / t, and the amount of the frother is 200-300 g / t, in terms of m (agent) / m (phosphogypsum).

[0040] In the embodiment, in steps S4 and S5, the amount of the mixed collector is 25-50 g / t, and the amount of the frother is 100-150 g / t, in terms of m (agent) / m (phosphogypsum).

[0041] In the embodiment, the stirring time after each addition of the agent is 3-5 min.

[0042] Example 1

[0043] (1) Grinding: 0.5% sodium hexametaphosphate is added to 250 g of phosphogypsum, and mixed and ball milled for 1 minute; wherein the main chemical components of the phosphogypsum are as follows in terms of weight percentage: CaSO4·2H2O content is 80.66%, phosphogypsum whiteness is 20.07%, SiO2 content is 8.26%, phosphorus content is 0.78%, fluorine content is 0.75%, organic matter content is 1.01%, pH value is 3.51, and 0.074 mm particle size content is 95.24%.

[0044] (2) Microbubble pretreatment: the phosphogypsum is slurried with water to achieve a slurry concentration of 25%, and an ultramicro bubble generator (bubble size less than 1 micron) is selected for pretreatment at 40°C for 10 minutes.

[0045] (3) One-stage rough reverse flotation: fully stirring and dispersing for 3 minutes before flotation and heating to 45±2°C, adjusting pH to 7±0.2 in the process; adding mixed collector of 1431 and emulsifier OP-10 in a mass ratio of 2:1, with a dosage of 50 / t, adding MIBC aqueous solution as a foaming agent after 3 minutes, with a dosage of 200 g / t; aerated reverse flotation for 3 minutes until the foam is white;

[0046] (4) One-stage clean reverse flotation: the phosphogypsum ore slurry in the tank is subjected to one-stage clean reverse flotation again; the one-stage clean reverse flotation maintains the above-mentioned temperature, and the above-mentioned mixed collector is added, with a dosage of 25 g / t, MIBC aqueous solution is added as a foaming agent after 3 minutes, with a dosage of 100 g / t; aerated reverse flotation for 3 minutes until the foam is white;

[0047] (5) Two-stage clean reverse flotation: the phosphogypsum ore slurry in the tank is subjected to two-stage clean reverse flotation again; the two-stage clean reverse flotation maintains the above-mentioned temperature, and the above-mentioned mixed collector is added, with a dosage of 25 g / t, MIBC aqueous solution is added as a foaming agent after 3 minutes, with a dosage of 100 g / t; aerated reverse flotation for 3 minutes until the foam is white;

[0048] (6) Drying: the purified phosphogypsum in the tank is directly subjected to suction filtration and drying (temperature 45-55°C) to obtain the final product high-grade phosphogypsum. Among them, the content of phosphogypsum CaSO4·2H2O is 94.17%, the yield of phosphogypsum concentrate is 69.26%, the whiteness of phosphogypsum is 68.91%, the content of SiO2 is 0.97%, the content of organic matter is 0.11%, the content of phosphorus is 0.12%, and the content of fluorine is 0.08%, reaching the national first-class building material index.

[0049] Example 2

[0050] Compared with Example 1, in Example 2, the dosage of the mixed collector for roughing is increased to 100 / t, and the dosage of MIBC is increased to 300 g / t; the dosage of the mixed collector for cleaning is increased to 50 / t, and the dosage of MIBC is increased to 150 g / t. The main chemical components of the raw ore are as follows in terms of weight percentage: the content of CaSO4·2H2O is 79.64%, the whiteness of phosphogypsum is 19.97%, the content of SiO2 is 9.01%, the content of phosphorus is 0.82%, the content of fluorine is 0.78%, the content of organic matter is 0.98%, the pH value is 3.34, and the content of particles with a size of 0.074 mm or less is 91.7%. After flotation, the content of phosphogypsum CaSO4·2H2O in the concentrate is 95.52%, the yield is 60.73%, the whiteness of phosphogypsum is 69.45%, the content of SiO2 is 0.56%, the content of organic matter is 0.07%, the content of phosphorus is 0.15%, and the content of fluorine is 0.10%.

[0051] Example 3

[0052] Compared with Example 1, in Example 3, the mixed collector is changed to the mixed collector of 1431 and emulsifier OP-10 with a mass ratio of 9:1. The main chemical components of the raw ore are as follows in terms of percentage by weight: CaSO4·2H2O content is 80.12%, phosphogypsum whiteness is 20.21%, SiO2 content is 8.74%, phosphorus content is 0.91%, fluorine content is 0.84%, organic matter content is 1.14%, pH value is 3.78, and particle size content of 0.074 mm or less is 94.3%. After flotation, the CaSO4·2H2O content of the phosphogypsum in the concentrate is 94.81%, the yield is 67.48%, the phosphogypsum whiteness is 67.98%, the SiO2 content is 0.76%, the organic matter content is 0.08%, the phosphorus content is 0.14%, and the fluorine content is 0.10%.

[0053] Example 4

[0054] Compared with Example 1, in Example 4, the mixed collector is changed to the mixed collector of 1431 and emulsifier OP-10 with a mass ratio of 1:1. The main chemical components of the raw ore are as follows in terms of percentage by weight: CaSO4·2H2O content is 80.47%, phosphogypsum whiteness is 20.45%, SiO2 content is 8.89%, phosphorus content is 0.81%, fluorine content is 0.78%, organic matter content is 1.06%, pH value is 3.64, and particle size content of 0.074 mm or less is 95.3%. After flotation, the CaSO4·2H2O content of the phosphogypsum in the concentrate is 95.84%, the yield is 70.88%, the phosphogypsum whiteness is 68.86%, the SiO2 content is 0.98%, the organic matter content is 0.14%, the phosphorus content is 0.09%, and the fluorine content is 0.07%.

[0055] Comparative Example 1

[0056] Compared with Example 1, in Comparative Example 1, no micro-bubble pretreatment is taken, and the flotation purification experiment is carried out. The main chemical components of the raw ore are as follows in terms of percentage by weight: CaSO4·2H2O content is 80.27%, phosphogypsum whiteness is 20.41%, SiO2 content is 9.17%, phosphorus content is 0.84%, fluorine content is 0.80%, organic matter content is 1.02%, and pH value is 3.35. After flotation, the CaSO4·2H2O content of the phosphogypsum in the concentrate is 93.61%, the yield of the phosphogypsum concentrate is 55.49%, the phosphogypsum whiteness is 66.81%, the SiO2 content is 1.27%, the organic matter content is 0.17%, the phosphorus content is 0.64%, and the fluorine content is 0.71%.

[0057] It can be known from the comparison between Comparative Example 1 and Example 1 that the micro-bubble pretreatment can improve the yield, whiteness and desiliconization effect of the phosphogypsum, and effectively remove phosphorus impurities and fluorine impurities.

[0058] Comparative Example 2

[0059] Compared with Example 1, in Comparative Example 2, 1231 mixed with emulsifier OP-10 was used as a mixed reagent for comparison, and flotation purification experiments were carried out. The main chemical components of the raw ore were as follows in terms of percentage by weight: CaSO4·2H2O content was 81.43%, the whiteness of the phosphogypsum was 20.28%, SiO2 content was 8.02%, phosphorus content was 0.71%, fluorine content was 0.68%, pH value was 3.47, and organic matter content was 1.03%. After flotation, the CaSO4·2H2O content of the phosphogypsum in the concentrate was 93.24%, the phosphogypsum concentrate yield was 61.81%, the whiteness of the phosphogypsum concentrate was 65.16%, SiO2 content was 2.07%, organic matter content was 0.16%, phosphorus content was 0.17%, and fluorine content was 0.07%.

[0060] It can be known from the comparison between Comparative Example 2 and Example 1 that, similarly to the previous single-factor results, the yield, whiteness and desiliconization effect of the phosphogypsum were not as good as those of the mixed collector of 1431 and emulsifier OP-10 in Example 1 when the mixed collector of 1231 and emulsifier OP-10 was used.

[0061] Comparative Example 3

[0062] Compared with Example 1, in Comparative Example 3, the mixed collector was changed to a mixed collector of 1431 and emulsifier OP-10 with a mass ratio of 99:1. The main chemical components of the raw ore were as follows in terms of percentage by weight: CaSO4·2H2O content was 79.43%, the whiteness of the phosphogypsum was 19.16%, SiO2 content was 8.91%, phosphorus content was 0.89%, fluorine content was 0.71%, pH value was 3.84, and organic matter content was 1.17%. After flotation, the CaSO4·2H2O content of the phosphogypsum in the concentrate was 89.24%, the phosphogypsum concentrate yield was 71.81%, the whiteness of the phosphogypsum concentrate was 48.50%, SiO2 content was 2.67%, organic matter content was 0.46%, phosphorus content was 0.18%, and fluorine content was 0.07%.

[0063] Comparative Example 4

[0064] Compared with Example 1, in Comparative Example 4, the mixed collector is changed to the mixed collector of 1431 and emulsifier OP-10 with a mass ratio of 0.01:1. The main chemical components of the raw ore are as follows in percentage by weight: CaSO4·2H2O content is 80.21%, phosphogypsum whiteness is 20.08%, SiO2 content is 8.45%, phosphorus content is 0.79%, fluorine content is 0.75%, pH value is 3.41, and organic matter content is 1.06%. After flotation, the CaSO4·2H2O content in the phosphogypsum concentrate is 88.76%, the phosphogypsum concentrate yield is 68.45%, the phosphogypsum whiteness is 50.14%, the SiO2 content is 3.17%, the organic matter content is 0.51%, the phosphorus content is 0.17%, and the fluorine content is 0.08%.

[0065] It can be known from the comparison between Comparative Examples 3-4 and Example 1 that the ratio of 1431 and emulsifier OP-10 that is too high or too low is not conducive to improving the impurity removal and desilication effect of phosphogypsum, and only within the specific ratio range of the present application, the synergistic effect can be played.

[0066] The specific embodiments of the present application described above do not constitute a limitation on the protection scope of the present application. Any various other corresponding changes and modifications made according to the technical concept of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A green and efficient decolorization and upgrading method of phosphogypsum, characterized in that, The method comprises the following steps: Grinding: grinding the raw phosphogypsum ore; Micro-bubble pretreatment: the ground phosphogypsum is mixed with water to form a phosphogypsum slurry, and then the micro-bubble pretreatment is performed; First-stage rough reverse flotation: the phosphogypsum slurry after the micro-bubble pretreatment is adjusted to a pH of 6.5-7.5, and then heated to 40-50℃, and then mixed collector and frother are added, and after stirring and mixing, the first-stage rough reverse flotation is performed until the froth is white; First-stage fine reverse flotation: the phosphogypsum slurry after the first-stage rough reverse flotation is again mixed with the mixed collector and frother, and after stirring and mixing, the first-stage fine reverse flotation is performed until the froth is white; Second-stage fine reverse flotation: the phosphogypsum slurry after the second-stage fine reverse flotation is again mixed with the mixed collector and frother, and after stirring and mixing, the second-stage fine reverse flotation is performed until the froth is white; Drying: the phosphogypsum slurry after the second-stage fine reverse flotation is filtered and dried to obtain high-purity fine-grained gypsum dihydrate; The mixed collector is a combination of emulsifier OP-10 and tetradecyl trimethyl ammonium chloride.

2. The method for efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, The dispersant is added during the grinding process.

3. The method for efficient decolorization and upgrading of phosphogypsum according to claim 2, characterized in that, The dispersant is sodium hexametaphosphate, and the amount of the dispersant is 0.2%-0.8% of the mass of the phosphogypsum.

4. The method for efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, The particle size of the ground phosphogypsum is less than 200 mesh, and the particle size of 90% or more is less than 200 mesh.

5. The method for efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, The concentration of the phosphogypsum slurry is 20-40%.

6. The method for efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, An ultra-micron bubble generator is selected, the temperature of the micro-bubble pretreatment is 40-50℃, and the time of the micro-bubble pretreatment is 10-20min.

7. The method for efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, The pH adjusting agent used for adjusting the pH is at least one of sulfuric acid or calcium oxide.

8. The method for efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, In the mixed collector, the mass ratio of tetradecyl trimethyl ammonium chloride to emulsifier OP-10 is (1-9):

1.

9. The method for efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, The frother is methyl isobutyl carbinol.

10. The method for green and efficient decolorization and upgrading of phosphogypsum according to claim 1, characterized in that, In the first-stage rough reverse flotation, the amount of the mixed collector is 50-100g / t, and the amount of the frother is 200-300g / t; in the first-stage fine reverse flotation and the second-stage fine reverse flotation, the amount of the mixed collector is 25-50g / t, and the amount of the frother is 100-150g / t.

Images