Wet-process calcium phosphate and magnesium grading removal device system

Abstract

The utility model relates to a wet-process calcium phosphate and magnesium grading removal device system. A discharge port below a jacket crystallization tank I is connected with a phase splitting tank, the bottom of the phase splitting tank is connected with a plate-and-frame filter press, an outlet of the plate-and-frame filter press is connected with a clear liquid tank, and an outlet of a sulfuric acid preparation tank is connected with the clear liquid tank; two pipelines are arranged at the outlet of the clear liquid tank, one pipeline is conveyed to the jacket crystallization tank through the centrifugal pump, and the other pipeline is conveyed to the jacket crystallization tank through the centrifugal pump. An extracting agent enters a crystallization tank for reverse extraction with sulfuric acid, a mixed solution after reverse extraction enters a lower split-phase tank and is continuously pumped into an upper crystallization tank for reverse extraction, ammonium sulfate is added under a low-temperature condition to form ammonium magnesium sulfate crystals, and then crystallized ammonium magnesium sulfate turbid liquid is pumped into a lower thickener; and filtering the liquid with high solid content at the bottom of the thickener through a double-push centrifugal machine, continuously pumping the filtrate into a reverse extraction crystallization tank for continuous reverse extraction, and carrying out calcium and magnesium reverse extraction circulation on the reverse extraction liquid sulfuric acid all the time to produce calcium sulfate dihydrate and ammonium magnesium sulfate crystals.

Description

Technical Field

[0001] The utility model relates to a device system for removing calcium and magnesium ions from a metal ion-loaded P-15 extractant after wet-process phosphoric acid extraction in a sulfuric acid stripping process for regeneration of the P-15, and specifically, to a device system for precipitating calcium ions in the form of calcium sulfate dihydrate and magnesium ions in the form of ammonium magnesium sulfate in the P-15 extractant regeneration process. Background Art

[0002] P-15 is an extractant for extracting metal cations from phosphoric acid, primarily used for wet-process phosphoric acid purification. It belongs to the class of organophosphorus acidic extractants derived from sulfonated kerosene. Currently, regeneration of P-15 extractants typically involves stripping the metal ions from the extractant with strong acids, typically using sulfuric acid, hydrochloric acid, or nitric acid. The regenerated extractant then continues extraction, and the strong acid loaded with metal ions after stripping is reused, depending on the specific production unit. The primary metal ions in wet-process acid are iron, aluminum, magnesium, and calcium. Sulfuric acid solution is typically used to regenerate the extractant, and the calcium, magnesium, and aluminum loaded sulfuric acid solution is then removed by crystallization, allowing the sulfuric acid to be reused.

[0003] Currently, few manufacturers use P-15 extractant to purify wet-process phosphoric acid. It is a newly developed extraction technology. Extraction is usually carried out using a stirring and phase separation tank. This method has low extraction efficiency and complicated process. To simplify the process and improve extraction efficiency, Yidu Xingfa creatively uses an extraction centrifuge for wet-process phosphoric acid extraction and extractant regeneration. However, during the sulfuric acid regeneration process, calcium ions form calcium sulfate crystals in the sulfuric acid solution. Crystallization in the extraction centrifuge causes uneven separation of the light and heavy phases, interrupting the stripping. In addition, calcium sulfate is mixed into the subsequent magnesium ion crystallization, which increases the cost of subsequent high-quality utilization of metal ions. Summary of the Invention

[0004] In order to overcome the existing technical problems, the utility model provides a device system for graded removal of calcium and magnesium metal ions while avoiding crystallization in an extraction centrifuge.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: comprising a jacketed crystallization tank 1 and a jacketed crystallization tank 2,

[0006] The lower discharge port of the jacketed crystallization tank is connected to the phase separation tank, the bottom of the phase separation tank is connected to the plate and frame filter press, the outlet of the plate and frame filter press is connected to the clear liquid tank, and the outlet of the sulfuric acid preparation tank is connected to the clear liquid tank;

[0007] There are two pipelines at the outlet of the clear liquid tank, one pipeline is transported to the jacket crystallization tank through a centrifugal pump, and the other pipeline is transported to the jacket crystallization tank through a centrifugal pump.

[0008] The top of the jacketed crystallization tank is provided with an extractant inlet and a sulfuric acid solution inlet, and the jacket part is provided with a hot water inlet and a hot water outlet.

[0009] A sight glass is provided on the side of the phase separation tank to observe the phase separation interface, a mixed liquid feed port is provided in the middle, and the top is connected to the extractant temporary storage tank through an overflow port.

[0010] The second bottom outlet of the jacketed crystallization tank is connected to the thickener, the thickener is connected to the double-push centrifuge, and the double-push centrifuge is connected to the clear liquid tank.

[0011] The clear liquid tank is connected to the jacketed crystallization tank one through the centrifugal pump two.

[0012] The filter residues produced by the plate and frame filter press and the double-push centrifuge are sent to other sections for processing.

[0013] The heat medium of the jacketed crystallization tank 1 is hot water.

[0014] The refrigerant of the jacketed crystallization tank 2 is chilled water.

[0015] The utility model has the following beneficial effects: the utility model adopts sulfuric acid stripping p-15 extractant, which can strip out part of the aluminum ions and all the calcium and magnesium ions in the extractant, and can respectively obtain high-quality calcium sulfate dihydrate and ammonium magnesium sulfate crystals; while solving the problem of stripping centrifuge blockage, high-purity calcium sulfate dihydrate and ammonium magnesium sulfate crystals are also obtained.

[0016] The process of this utility model has the following characteristics.

[0017] 1. The extractant is directly stirred with the sulfuric acid solution, wherein calcium and magnesium ions enter the sulfuric acid solution first. Then, there will be only a large amount of calcium and magnesium ions in the sulfuric acid. As the number of sulfuric acid cycles increases, aluminum ions will enter less or even not enter the sulfuric acid, ensuring that only calcium and magnesium ions are crystallized in this process during the extraction process.

[0018] 2. In the sulfuric acid solution, calcium ions will preferentially generate calcium sulfate dihydrate without other impurities to obtain high-purity calcium sulfate dihydrate, with a whiteness of 95% and a calcium sulfate dihydrate content of more than 95%.

[0019] 3. During the crystallization process of ammonium magnesium sulfate, fluoride ions will be extracted from the extractant into the sulfuric acid solution. Fluoride ions will inhibit the formation of ammonium aluminum sulfate, and the aluminum ion content is much lower than that of magnesium ions. Therefore, during the crystallization process of ammonium magnesium sulfate, the required temperature is close to room temperature, so high-purity ammonium magnesium sulfate crystals will be obtained.

[0020] 4. Ammonium sulfate will be added during the crystallization of magnesium ions. The sulfuric acid solution mixed with ammonium sulfate will not affect the stripping efficiency of calcium and magnesium ions, and the ammonium ions will not enter the extractant to enter the next stripping stage. In addition, the amount of ammonium sulfate input in the crystallization of magnesium ammonium sulfate will be reduced to reduce costs.

[0021] 5. If the magnesium ion content in the clear sulfuric acid solution after stripping does not exceed 20,000 ppm, it does not need to enter the magnesium ammonium sulfate crystallization. After adding sulfuric acid, it can be directly returned to the extractant for stripping, which greatly reduces sulfuric acid consumption and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the device of the present utility model.

[0023] In the figure, 1 is the first jacketed crystallization tank, 2 is the phase separation tank, 3 is the plate and frame filter press, 4 is the sulfuric acid clear liquid tank, 5 is the sulfuric acid preparation tank, 6 is the first centrifugal pump, 7 is the second jacketed crystallization tank, 8 is the thickener, 9 is the double-push centrifuge, 10 is the sulfuric acid clear liquid tank, 11 is the second centrifugal pump, and 12 is the extractant temporary storage tank. DETAILED DESCRIPTION

[0024] The present invention is further described below with reference to specific embodiments.

[0025] like Figure 1 As shown, a wet-process calcium phosphate and magnesium graded removal device system includes a jacketed crystallization tank 1 and a jacketed crystallization tank 2 7. The top of the jacketed crystallization tank 1 is provided with an inlet for a loaded metal ion extractant and an inlet for a sulfuric acid solution, and the jacket portion is provided with a hot water inlet and a hot water outlet. The discharge port below the jacketed crystallization tank 1 overflows into the phase separation tank 2 below. The phase separation tank 2 is provided with a sight glass on the side to observe the phase separation interface, a mixed liquid feed port in the middle, and an overflow port on the top. The overflowed extractant enters the extractant temporary storage tank 12. The regenerated extractant is the extractant for removing magnesium and calcium.

[0026] A plate and frame filter press 3 is connected below the phase separation tank 2. After phase separation, the solid-containing sulfuric acid liquid enters the plate and frame filter press 3 for solid-liquid separation to obtain calcium sulfate dihydrate filter residue, and the filtrate enters the clear liquid tank 4. The clear liquid tank 4 is connected to the clear liquid of the plate and frame filter press 3 and the sulfuric acid pipeline from the sulfuric acid preparation tank 5. The filtrate after filtration by the plate and frame filter press 3 and the sulfuric acid from the sulfuric acid preparation tank 5 are mixed under the action of a centrifugal pump 6 to maintain the concentration of the sulfuric acid solution. After the configuration is completed, the sulfuric acid solution is provided with two pipelines, one pipeline is transported to the jacket crystallization tank 1 through the centrifugal pump 6, and the other pipeline is transported to the jacket crystallization tank 2 7 through the centrifugal pump 6;

[0027] The top of the jacketed crystallizer 2 7 is connected to the pipeline from the clear liquid tank 4 and the solid ammonium sulfate feeding port, the jacket part is also connected to the chilled water inlet and outlet, the thickener 8 is connected to the pipeline from the crystallizer 2 above, the double-push centrifuge 9 is connected to the thickener 8 pipeline above, the clear liquid tank 10 is connected to the pipeline from the double-push centrifuge 9 above, and the stored clear liquid is pumped into the jacketed crystallizer tank 1 through the centrifugal pump 2 11 to continue stripping crystallization;

[0028] The filter residues produced by the plate and frame filter press 3 and the double-push centrifuge 9 are sent to other sections for processing.

[0029] The heat medium of the jacketed crystallization tank 1 is hot water.

[0030] The refrigerant of the jacketed crystallization tank 2 7 is chilled water.

[0031] (1) Add 30%-40% sulfuric acid solution and loaded p-15 extractant in a volume ratio of 1:10-15, and place them into crystallization tank 1 at 60°C for stirring and stripping.

[0032] (2) After the extraction is completed, the mixed material enters the phase separation tank 2 from the crystallization tank 1. The completely separated extractant overflows to the organic phase temporary storage tank 12. The solid liquid below passes through the plate and frame filter press 3. The filter residue is sent to other sections, and the filtrate enters the clear liquid tank 4. After regeneration, the magnesium and calcium ion content of the extractant is less than 50ppm, the purity of calcium sulfate reaches 95%, the whiteness reaches 95%, and the average particle size is 10um.

[0033] (3) The filtered filtrate is mixed with 50%-60% sulfuric acid from the sulfuric acid preparation tank 5 under the action of the centrifugal pump 6 to restore the sulfuric acid concentration to 30%-40%.

[0034] (4) When the magnesium ion content in the filtrate is lower than 20,000 ppm, the sulfuric acid solution is pumped into the crystallization tank 1 through the centrifugal pump 6.

[0035] (5) When the magnesium ion content in the filtrate is higher than 20,000 ppm, the sulfuric acid solution is pumped into the jacketed crystallization tank 27, and then 10%-20% ammonium sulfate is added, and the crystallization is stirred at 5-15°C for 2 hours.

[0036] (6) After the crystallization is completed, the solution is concentrated by a thickener 8, and the solid sulfuric acid liquid below is separated by a double-push centrifuge 9 to obtain a magnesium ammonium sulfate residue with a content of 95% and a particle size of 168 μm. The filtrate enters the clear liquid tank 10 and is pumped into the jacketed crystallization tank 1 through a centrifugal pump 2 11 to complete the cycle.

[0037] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A wet process calcium phosphate and magnesium graded removal device system, comprising a jacketed crystallization tank 1 (1) and a jacketed crystallization tank 2 (7), characterized in that: The lower discharge port of the jacketed crystallization tank (1) is connected to the phase separation tank (2), the bottom of the phase separation tank (2) is connected to the plate and frame filter press (3), the outlet of the plate and frame filter press (3) is connected to the clear liquid tank (4), and the outlet of the sulfuric acid preparation tank (5) is connected to the clear liquid tank (4); The outlet of the clear liquid tank (4) is provided with two pipelines, one pipeline is transported to the jacket crystallization tank (1) through the centrifugal pump (6), and the other pipeline is transported to the jacket crystallization tank (7) through the centrifugal pump (6).

2. The wet-process calcium phosphate and magnesium graded removal device system according to claim 1, characterized in that: The top of the jacketed crystallization tank (1) is provided with an extractant inlet and a sulfuric acid solution inlet, and the jacket portion is provided with a hot water inlet and a hot water outlet.

3. The wet-process calcium phosphate and magnesium graded removal device system according to claim 1, characterized in that: The side of the phase separation tank (2) is provided with a sight glass for observing the phase separation interface, the middle is provided with a mixed liquid feed port, and the top is connected to the extractant temporary storage tank (12) through an overflow port.

4. The wet-process calcium phosphate and magnesium graded removal device system according to claim 1, characterized in that: The bottom outlet of the second jacketed crystallization tank (7) is connected to the thickener (8), the thickener (8) is connected to the double-push centrifuge (9), and the double-push centrifuge (9) is connected to the clear liquid tank (10).

5. The wet process calcium phosphate and magnesium graded removal device system according to claim 1, characterized in that: The clear liquid tank (10) is connected to the jacketed crystallization tank (1) via the second centrifugal pump (11).

Images