A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock

Abstract

The application discloses a method for producing high-quality wet-process phosphoric acid by using low-fineness phosphate ore, and the method comprises the following steps: obtaining ball-milled raw ore with relatively low fineness by optimizing the ball-milling parameters in the ball-milling process of phosphate ore; feeding the ball-milled raw ore into a flotation device to perform reverse flotation and obtaining phosphate concentrate; feeding the phosphate concentrate into a reaction tank after pressure filtration, and performing a decomposition reaction with excessive phosphoric acid under the action of an organic solubility-promoting agent, and then performing solid-liquid separation to obtain filtrate; adding sulfuric acid into the filtrate, continuing to react, and then performing filtration to obtain high-quality phosphoric acid and phosphogypsum. The phosphate ore is coarsely ground in the ball-milling process, the overall phosphate ore particle size is reduced, and the ball-milling energy consumption can be greatly reduced; the organic solubility-promoting agent can increase the solubility of calcium phosphate, reduce the reaction time, and reduce the acid-ore ratio while promoting the decomposition of the phosphate ore and increasing the decomposition rate of the phosphate ore; the large-particle acid-insoluble impurities have good filtration performance and cannot cause passivation reaction caused by calcium sulfate wrapping the phosphate ore.

Description

Technical Field

[0001] This invention relates to a method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock, belonging to the field of wet-process phosphoric acid technology. Background Technology

[0002] Generally, the traditional wet phosphoric acid process uses a mixture of phosphoric and sulfuric acids to decompose phosphate rock. After the reaction, the mixture is filtered to obtain wet phosphoric acid and phosphogypsum. However, because phosphate rock contains a large number of harmful impurities, some of these impurities enter the liquid phase during the phosphate rock decomposition process, while others enter the solid phase with the precipitation of calcium sulfate. This results in poor quality of the finished phosphoric acid and a large number of impurities in the by-product phosphogypsum, which seriously affects the production of downstream products and the comprehensive utilization of phosphogypsum.

[0003] To ensure the normal production of wet-process phosphoric acid, grinding and flotation methods are used to enrich the P2O5 element in the phosphate rock and remove some impurities; this is the mineral processing technology. However, the mineral processing results in some loss of P2O5 in the phosphate rock, with a recovery rate generally below 85%, and the cost is high, especially the grinding process, which consumes a great deal of energy, accounting for more than 50% of the total energy consumption of the entire mineral processing process. In recent years, with the gradual decrease in phosphate ore grade and the gradual increase in impurity content, the difficulty of mineral processing has gradually increased. Therefore, improving the P2O5 recovery rate, reducing energy consumption, and reducing the difficulty of mineral processing have become key issues that urgently need to be addressed in this industry.

[0004] Grinding fineness is one of the important parameters affecting flotation indicators. The finer the phosphate rock is ground, the better the flotation impurity removal effect, the higher the degree of subsequent reaction with the phosphate-sulfur mixed acid, the more thorough the decomposition of the phosphate rock, the higher the P2O5 yield, and the better the quality of phosphoric acid. To ensure the normal production of wet-process phosphoric acid, the raw ore is often appropriately finely ground during the grinding process in industry. However, this method will increase grinding energy consumption, and high-fineness phosphate rock will have poor foaming conditions during flotation, which will increase the flotation difficulty and reduce the P2O5 recovery rate of phosphate concentrate in the beneficiation stage.

[0005] Therefore, finding a method to produce high-quality wet-process phosphoric acid using low-fineness phosphate rock, while reducing energy consumption in the beneficiation process, lowering the difficulty of flotation, and increasing the P2O5 recovery rate of phosphate concentrate, is of great significance to this industry. Summary of the Invention

[0006] To address the shortcomings of existing wet-process phosphoric acid production processes, this invention provides a method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock. This method involves appropriately reducing the grinding fineness of the phosphate rock during the beneficiation process, and employing phosphoric acid decomposition of the phosphate rock followed by filtration and sulfuric acid crystallization during the wet-process phosphoric acid production process. This approach ensures the normal production of high-quality phosphoric acid and phosphogypsum while reducing energy consumption during beneficiation, lowering the difficulty of flotation, and increasing the P2O5 recovery rate of the phosphate concentrate.

[0007] The technical solution of the present invention is as follows: During the grinding process of phosphate rock raw ore, the grinding parameters are optimized to reduce the grinding fineness of the ball milled raw ore, and then it is sent to a flotation device for reverse flotation to obtain phosphate concentrate with relatively low fineness and relatively high impurity content. After pressure filtration, the phosphate concentrate is sent to a reaction tank and decomposed with excess phosphoric acid under the action of organic solvent. After the reaction is completed, the filtrate is obtained by solid-liquid separation. Sulfuric acid is added to the filtrate, and after reaction and filtration, wet phosphoric acid and phosphogypsum can be obtained.

[0008] A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) By optimizing the grinding parameters during the grinding process of phosphate rock ore, ball milled ore with relatively low fineness can be obtained; (2) The ball milled raw ore obtained in step (1) is fed into a flotation device for reverse flotation to obtain phosphate concentrate with relatively low fineness and relatively high impurity content; (3) The phosphate concentrate obtained in step (2) is filtered by pressure and then sent to the reaction tank. Under the action of organic solvent, it is decomposed with excess phosphoric acid. After the reaction is completed, solid-liquid separation is performed to obtain filtrate. (4) Add sulfuric acid to the filtrate obtained in step (3), continue the reaction and then filter to obtain high-quality phosphoric acid and phosphogypsum.

[0009] In step (1), the phosphate rock ore contains P2O5 ≥ 16wt%, Al2O3 ≤ 5.0wt%, Fe2O3 ≤ 2.5wt%, and MgO ≤ 3.0wt%.

[0010] The elemental composition of the ball-milled raw ore is the same as that of the phosphate rock raw ore, and the grinding fineness is -0.074mm, accounting for 50~60%.

[0011] In step (2), the fineness of the phosphate concentrate is the same as that of the ball-milled raw ore, with P2O5 ≥ 28wt%, Al2O3 ≤ 4.0wt%, Fe2O3 ≤ 2.0wt%, and MgO ≤ 2.5wt%.

[0012] In step (3), the organic solvent is acetic acid or an acetate or a mixture of both or more.

[0013] Preferably, the acetate includes potassium acetate, sodium acetate, ammonium acetate, etc.

[0014] The amount of organic co-solvent added is 0.01% to 0.05% of the mass of the decomposition reaction system.

[0015] During the decomposition reaction, the content of phosphoric acid P2O5 is 24~28wt%, the acid-to-ore ratio is 4~8, the reaction temperature is 60~75℃, and the reaction time is 60~90min.

[0016] In step (4), the liquid phase SO4 is controlled during the reaction process of adding sulfuric acid. 2- ≤0.5wt%, reaction temperature is 75~85℃, reaction time is 1~2h.

[0017] High-quality phosphoric acid is dilute phosphoric acid with a P2O5 content of 24~28wt%, and high-quality phosphogypsum is clean gypsum with a purity greater than 97% and a whiteness greater than 92.

[0018] The beneficial effects of this invention are as follows: (1) The present invention reduces the overall particle size of phosphate rock by appropriately coarse grinding the raw phosphate rock during the grinding process, which can significantly reduce grinding energy consumption.

[0019] (2) The low-fineness phosphate rock used in this invention has a better foam condition during the flotation process, which helps to reduce the flotation difficulty and improve the P2O5 recovery rate of phosphate concentrate in the beneficiation section.

[0020] (3) In the process of phosphoric acid decomposition of phosphate rock, the present invention adds an organic solvent to promote the decomposition of phosphate rock and increase the decomposition rate of phosphate rock. At the same time, it increases the solubility of the acid hydrolysis product calcium dihydrogen phosphate, reduces the reaction time, and lowers the acid-to-ore ratio, which is beneficial to reduce the production load and improve the production efficiency.

[0021] (4) The organic solvent added in this invention has advantages such as low addition amount, low cost, and low equipment corrosion compared with other solvents (such as hydrochloric acid, hydrochloride, nitric acid, nitrate, etc.), and no additional impurity removal process is required to remove chloride ions, nitrate ions and other anions.

[0022] (5) In the wet process of phosphoric acid production, the present invention adopts the method of decomposing phosphate rock with phosphoric acid, filtering and then adding sulfuric acid for crystallization, which can effectively inhibit the dissolution of impurities in phosphate rock, and has good filtering performance for large-particle acid-insoluble impurities. It also avoids the passivation reaction caused by calcium sulfate encapsulating phosphate rock, so that low-fineness, high-impurity phosphate concentrate can be decomposed normally, and high-quality phosphoric acid and phosphogypsum can be obtained at the same time. Attached Figure Description

[0023] Figure 1 A photograph of the experimental equipment used in this invention before corrosion.

[0024] Figure 2 A photograph of the experimental equipment used in this invention after corrosion. Detailed Implementation

[0025] To enhance the understanding of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0026] Example 1 A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) The phosphate rock ore with P2O5 content of 16.7wt%, Al2O3 content of 4.5wt%, Fe2O3 content of 2.1wt%, and MgO content of 2.7wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 55% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 30.4wt%, an Al2O3 content of 3.6wt%, an Fe2O3 content of 1.8wt%, and an MgO content of 2.0wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) After the phosphate concentrate obtained in step (2) is filtered by pressure, it is sent to the reaction tank, and 0.01% sodium acetate (organic co-solvent) of the decomposition reaction system is added. Then, excess phosphoric acid with a P2O5 content of 26wt% is added to carry out the decomposition reaction. The acid-ore ratio is controlled at 5, the reaction temperature is 70℃, and the reaction time is 90min. After the reaction is completed, the solution is filtered to obtain the filtrate. (4) Add sulfuric acid to the filtrate obtained in step (3) to control the SO4 in the liquid phase. 2- The reaction was carried out at a concentration of 0.3 wt%, a reaction temperature of 80 ℃, and a reaction time of 90 min. After the reaction was completed, the mixture was filtered to obtain dilute phosphoric acid with a P2O5 content of 27.3 wt%, an Al2O3 content of 0.93 wt%, an Fe2O3 content of 0.18 wt%, and an MgO content of 0.64 wt%, and phosphogypsum with a purity of 97.4% and a whiteness of 92.8.

[0027] Example 2 A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) The phosphate rock ore with P2O5 content of 17.4wt%, Al2O3 content of 4.4wt%, Fe2O3 content of 2.4wt%, and MgO content of 2.5wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 55% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 30.7wt%, an Al2O3 content of 3.2wt%, an Fe2O3 content of 2.0wt%, and an MgO content of 2.2wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) After the phosphate concentrate obtained in step (2) is filtered by pressure, it is sent to the reaction tank, and then an excess of phosphoric acid with a P2O5 content of 26wt% is added for decomposition reaction (without adding organic co-solvent). The acid-ore ratio is controlled at 12, the reaction temperature is 72℃, and the reaction time is 180min. After the reaction is completed, the solution is filtered to obtain the filtrate. (4) Add sulfuric acid to the filtrate obtained in step (3) to control the SO4 in the liquid phase. 2- The reaction was carried out at a concentration of 0.4 wt%, a reaction temperature of 78 ℃, and a reaction time of 100 min. After the reaction was completed, the mixture was filtered to obtain dilute phosphoric acid with a P2O5 content of 26.9 wt%, an Al2O3 content of 0.95 wt%, an Fe2O3 content of 0.19 wt%, and an MgO content of 0.66 wt%, and phosphogypsum with a purity of 97.2% and a whiteness of 92.1.

[0028] Example 3 A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) The phosphate rock ore with P2O5 content of 17.1wt%, Al2O3 content of 4.3wt%, Fe2O3 content of 2.0wt%, and MgO content of 2.4wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 83% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 31.5wt%, an Al2O3 content of 2.9wt%, an Fe2O3 content of 1.3wt%, and an MgO content of 1.6wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) After the phosphate concentrate obtained in step (2) is filtered by pressure, it is sent to the reaction tank, and 0.02% of acetic acid (organic co-solvent) of the decomposition reaction system is added. Then, excess phosphoric acid with a P2O5 content of 26.4wt% is added to carry out the decomposition reaction. The acid-ore ratio is controlled at 5, the reaction temperature is 68℃, and the reaction time is 60min. After the reaction is completed, the solution is filtered to obtain the filtrate. (4) Add sulfuric acid to the filtrate obtained in step (3) to control the SO4 in the liquid phase. 2- The reaction temperature was 78℃, the reaction time was 80 min, and the mixture was filtered after the reaction to obtain dilute phosphoric acid with a P2O5 content of 26.9 wt%, an Al2O3 content of 0.90 wt%, an Fe2O3 content of 0.21 wt%, and an MgO content of 0.62 wt%, and phosphogypsum with a purity of 97.1% and a whiteness of 92.5.

[0029] Example 4 A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) The phosphate rock ore with P2O5 content of 16.3wt%, Al2O3 content of 4.6wt%, Fe2O3 content of 2.2wt%, and MgO content of 2.5wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 42% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 29.2wt%, an Al2O3 content of 3.8wt%, an Fe2O3 content of 1.9wt%, and an MgO content of 2.3wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) After the phosphate concentrate obtained in step (2) is filtered by pressure, it is sent to the reaction tank. Add a mixture of acetic acid and sodium acetate (organic co-solvent, wherein the mass ratio of acetic acid and sodium acetate is 1:1) of 0.03% by mass of the decomposition reaction system. Then add excess phosphoric acid with a P2O5 content of 26.9wt% for decomposition reaction. Control the acid-ore ratio to be 8, the reaction temperature to be 73℃, and the reaction time to be 70min. After the reaction is completed, filter to obtain the filtrate. (4) Add sulfuric acid to the filtrate obtained in step (3) to control the SO4 in the liquid phase. 2- The reaction was carried out at a concentration of 0.5 wt%, a reaction temperature of 82 ℃, and a reaction time of 100 min. After the reaction was completed, the mixture was filtered to obtain dilute phosphoric acid with a P2O5 content of 27.3 wt%, an Al2O3 content of 1.43 wt%, an Fe2O3 content of 0.44 wt%, and an MgO content of 1.06 wt%, and phosphogypsum with a purity of 97.5% and a whiteness of 93.1.

[0030] Example 5 A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) The phosphate rock ore with P2O5 content of 16.5wt%, Al2O3 content of 4.1wt%, Fe2O3 content of 2.3wt%, and MgO content of 2.7wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 57% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 30.1wt%, an Al2O3 content of 3.3wt%, an Fe2O3 content of 1.9wt%, and an MgO content of 2.1wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) The phosphate concentrate slurry obtained in step (2) is fed into the reaction tank, and 0.05% (by mass) of acetic acid (organic co-solvent) of the decomposition reaction system is added. Then, a phosphoric acid-sulfur mixture is added to carry out the extraction reaction, and the liquid phase P2O5 content is controlled to be 27.1 wt% and SO4 content is controlled to be 100 wt%. 2-The concentration was 3.0 wt%, the liquid-to-solid ratio was 2.3, the reaction temperature was 80℃, and the reaction time was 180 min. After the reaction was completed, the mixture was filtered to obtain dilute phosphoric acid with a P2O5 content of 27.1 wt%, an Al2O3 content of 1.32 wt%, an Fe2O3 content of 0.28 wt%, and an MgO content of 0.98 wt%, and phosphogypsum with a purity of 81.6% and a whiteness of 29.4.

[0031] Example 6 A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) The phosphate rock ore with P2O5 content of 16.9wt%, Al2O3 content of 4.2wt%, Fe2O3 content of 2.4wt%, and MgO content of 2.5wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 54% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 30.8wt%, an Al2O3 content of 3.5wt%, an Fe2O3 content of 1.9wt%, and an MgO content of 1.8wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) After the phosphate concentrate obtained in step (2) is filtered by pressure, it is sent to the reaction tank, and 10% sodium chloride (non-organic co-solvent) of the decomposition reaction system is added. Then, 90% phosphoric acid with a P2O5 content of 26.8wt% is added to carry out the decomposition reaction. The acid-ore ratio is controlled at 6, the reaction temperature is 73℃, and the reaction time is 80min. After the reaction is completed, the solution is filtered to obtain the filtrate. (4) Add sulfuric acid to the filtrate obtained in step (3) to control the SO4 in the liquid phase. 2- The reaction temperature was 79℃, the reaction time was 70 min, and the mixture was filtered after the reaction to obtain dilute phosphoric acid with a P2O5 content of 22.8 wt%, an Al2O3 content of 1.13 wt%, an Fe2O3 content of 0.24 wt%, and an MgO content of 0.82 wt%, and phosphogypsum with a purity of 97.5% and a whiteness of 92.6.

[0032] Example 7 A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock includes the following steps: (1) The phosphate rock ore with P2O5 content of 16.2wt%, Al2O3 content of 4.4wt%, Fe2O3 content of 2.3wt%, and MgO content of 2.3wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 58% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 31.0 wt%, an Al2O3 content of 3.7 wt%, an Fe2O3 content of 1.7 wt%, and an MgO content of 2.2 wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) After the phosphate concentrate obtained in step (2) is filtered by pressure, it is sent to the reaction tank, and 15% sodium nitrate (non-organic co-solvent) of the decomposition reaction system is added. Then, excess phosphoric acid with a P2O5 content of 26.5wt% is added to carry out the decomposition reaction. The acid-ore ratio is controlled at 5, the reaction temperature is 74℃, and the reaction time is 85min. After the reaction is completed, the solution is filtered to obtain the filtrate. (4) Add sulfuric acid to the filtrate obtained in step (3) to control the SO4 in the liquid phase. 2- The reaction temperature was 78℃, the reaction time was 90 min, and the mixture was filtered after the reaction to obtain dilute phosphoric acid with a P2O5 content of 23.5 wt%, an Al2O3 content of 1.09 wt%, an Fe2O3 content of 0.28 wt%, and an MgO content of 0.89 wt%, and phosphogypsum with a purity of 97.2% and a whiteness of 92.7.

[0033] Comparative Example The comparative example uses currently known mineral processing technology and wet phosphoric acid production technology. Phosphate concentrate with normal grinding fineness is extracted and reacted with phosphate-sulfur mixed acid, and then filtered to obtain wet phosphoric acid and phosphogypsum. This is used to compare with a method for producing high-quality wet phosphoric acid using low-fineness phosphate ore provided by the present invention.

[0034] A method for producing wet-process phosphoric acid includes the following steps: (1) The phosphate rock ore with P2O5 content of 17.3wt%, Al2O3 content of 4.4wt%, Fe2O3 content of 1.8wt%, and MgO content of 2.5wt% was crushed into ball mill ore with a grinding fineness of -0.074mm accounting for 85% by ball milling. (2) The ball milled raw ore obtained in step (1) is sent to the flotation device for reverse flotation. After testing, the obtained phosphate concentrate has a P2O5 content of 32.0 wt%, an Al2O3 content of 2.7 wt%, an Fe2O3 content of 1.4 wt%, and an MgO content of 1.7 wt%. The fineness of the phosphate concentrate is the same as that of the ball milled raw ore. (3) The phosphate concentrate slurry obtained in step (2) is fed into the reaction tank and subjected to an extraction reaction with a mixture of phosphoric and sulfuric acids. The liquid phase P2O5 content is controlled to be 26.5 wt% and SO4 content to be 10 wt%. 2- The concentration was 3.0 wt%, the liquid-to-solid ratio was 2.3, the reaction temperature was 80℃, and the reaction time was 180 min; (4) After the reaction is completed, the slurry is filtered by a disc filter to obtain dilute phosphoric acid with a P2O5 content of 26.5wt%, an Al2O3 content of 0.96wt%, an Fe2O3 content of 0.22wt%, an MgO content of 0.60wt%, and phosphogypsum with a purity of 82.3% and a whiteness of 30.7.

[0035] The process parameters of Examples 1-5 and the comparative examples were tested, and the results are shown in Table 1.

[0036] Table 1. Test results of process parameters for Examples 1-5 and the comparative examples.

[0037] Note 1: The grinding fineness is the percentage of -0.074mm.

[0038] Note 2: The impurity content is the sum of the contents of Al2O3, Fe2O3, and MgO.

[0039] Note 3: The number of corrosion resistance tests refers to the number of times the same model of equipment is subjected to repeated experiments when it is corroded to the same degree using the same process. Figure 1 This is a rendering of the equipment before corrosion. Figure 2 This is a diagram showing the effect after corrosion, specifically a diagram showing the effect of corrosion at the same degree.

Claims

1. A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock, characterized in that, Includes the following steps: (1) By optimizing the grinding parameters during the grinding process of phosphate rock ore, a ball-milled ore with a relatively low fineness is obtained. The elemental composition of the ball-milled ore is the same as that of the phosphate rock ore, and the grinding fineness is -0.074 mm, accounting for 50~60%. (2) The ball milled raw ore obtained in step (1) is fed into a flotation device for reverse flotation to obtain phosphate concentrate with relatively low fineness and relatively high impurity content; (3) The phosphate concentrate obtained in step (2) is filtered by pressure and then fed into a reaction tank. Under the action of an organic solvent, it undergoes a decomposition reaction with excess phosphoric acid. After the reaction is completed, solid-liquid separation is performed to obtain the filtrate. The organic solvent is a mixture of acetic acid and acetate. The acetate includes potassium acetate, sodium acetate, or ammonium acetate. The amount of organic solvent added is 0.01% to 0.05% of the mass of the decomposition reaction system. (4) Add sulfuric acid to the filtrate obtained in step (3), continue the reaction and then filter to obtain high-quality phosphoric acid and phosphogypsum.

2. The method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock according to claim 1, characterized in that, In step (1), the phosphate rock ore contains P2O5 ≥ 16wt%, Al2O3 ≤ 5.0wt%, Fe2O3 ≤ 2.5wt%, and MgO ≤ 3.0wt%.

3. The method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock according to claim 1, characterized in that, In step (2), the fineness of the phosphate concentrate is the same as that of the ball-milled raw ore, with P2O5 ≥ 28wt%, Al2O3 ≤ 4.0wt%, Fe2O3 ≤ 2.0wt%, and MgO ≤ 2.5wt%.

4. The method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock according to claim 1, characterized in that, In step (3), during the decomposition reaction, the content of phosphoric acid P2O5 is 24~28wt%, the acid-to-ore ratio is 4~8, the reaction temperature is 60~75℃, and the reaction time is 60~90min.

5. A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock according to claim 1, characterized in that, In step (4), the liquid phase SO4 is controlled during the reaction process of adding sulfuric acid. 2- ≤0.5wt%, reaction temperature is 75~85℃, reaction time is 1~2h.

6. A method for producing high-quality wet-process phosphoric acid using low-fineness phosphate rock according to claim 1, characterized in that, In step (4), the high-quality phosphoric acid is dilute phosphoric acid with a P2O5 content of 24~28wt%, and the high-quality phosphogypsum is clean gypsum with a purity greater than 97% and a whiteness greater than 92.

Images