System for recovering phosphorus resource in calcium-magnesium liquid

Abstract

The system comprises a calcium and magnesium removal filtrate tank, a reaction tank, an ammonia water tank, a lime milk tank, a filter press and a heating concentrator, a discharge port of the calcium and magnesium removal filtrate tank is connected with a feed port of the reaction tank; a discharging hole of the ammonia water tank is connected with a feeding hole of the reaction tank; a discharge port of the lime milk tank is connected with a feed port of the reaction tank; a discharging hole of the reaction tank is connected with a feeding hole of the filter press; a liquid outlet of the filter press is connected with a feeding hole of the heating concentrator, before filtrate enters the heating concentrator, ammonia water, decalcified filtrate and lime milk generate phosphorus-containing precipitates in the reaction tank, the precipitates and the filtrate after reaction enter the filter press for solid-liquid separation, and the separated filtrate enters the heating concentrator for concentration, so that the phosphorus-containing precipitates are obtained. The precipitate is recovered; therefore, the phosphorus content of the filtrate entering the heating concentrator is reduced, the probability of solid precipitation in the heating concentrator is also reduced, the heater can be prevented from being blocked, and the phosphorus recovery rate is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of phosphate ore processing, in particular to a system for recovering phosphorus resources in calcium-magnesium liquid. Background Art

[0002] At present, the demand for phosphate resources in the phosphorus chemical industry is increasing, but rich ores are scarce, so it is necessary to fully recover the phosphorus element in the phosphate ore; when treating the decalcified magnesium filtrate, it is found that the decalcified magnesium filtrate is pumped into the preheater and is severely blocked after running for about 10 days; the first-effect heater is severely blocked after running for 10 days; the second-effect heater is severely blocked after running for 15 days; and there is scaling in the first-effect separator and the second-effect separator, which leads to scaling of the transfer pump outlet pipe under forced circulation conditions, small delivery volume and low production load.

[0003] In the process of extracting phosphorus from phosphate rock, the beneficiation by-products contain a certain amount of phosphorus. For example, Chinese patent CN112758972A discloses a method for preparing calcium sulfate, magnesium hydroxide and potassium magnesium nitrate from a calcium-magnesium leaching solution, which records: the decalcified magnesium leaching solution is pumped to a two-effect countercurrent evaporation device for concentration treatment to obtain the ammonium nitrate calcium-magnesium concentrated solution; therefore, the present application provides a system for recovering phosphorus resources in calcium-magnesium solution, which can avoid heater blockage and improve the recovery rate of phosphorus. Utility Model Content

[0004] In order to overcome the deficiencies of the prior art, the utility model provides a system for recovering phosphorus resources in calcium-magnesium solution, which can avoid heater blockage and improve the recovery rate of phosphorus element.

[0005] The technical solution adopted by the utility model to solve its technical problems is:

[0006] A system for recovering phosphorus resources in calcium and magnesium solution, comprising a decalcified magnesium filtrate tank, a reaction tank, an ammonia water tank, a lime milk tank, a filter press and a heating concentrator;

[0007] The discharge port of the decalcified magnesium filtrate tank is connected to the feed port of the reaction tank;

[0008] The discharge port of the ammonia water tank is connected to the feed port of the reaction tank;

[0009] The discharge port of the lime milk tank is connected to the feed port of the reaction tank;

[0010] The discharge port of the reaction tank is connected to the feed port of the filter press;

[0011] The liquid outlet of the filter press is connected to the feed inlet of the heating concentrator.

[0012] In the system for recovering phosphorus resources in calcium-magnesium solution as described above, the slag outlet of the filter press is connected to a filter residue collecting tank.

[0013] In the system for recovering phosphorus resources in calcium-magnesium solution as described above, a filtrate tube is provided on the discharge port of the filter press, the filtrate tube is connected to the heating concentrator, and a sight glass is provided on the filtrate tube.

[0014] In the system for recovering phosphorus resources in calcium-magnesium solution as described above, an agitator is provided in the reaction tank.

[0015] The system for recovering phosphorus resources in calcium-magnesium solution as described above further includes a buffer tank, the feed port of the buffer tank is connected to the liquid outlet of the filter press, and the discharge port of the buffer tank is connected to the heating concentrator.

[0016] The system for recovering phosphorus resources in calcium-magnesium solution as described above also includes a preheater, the feed port of the preheater is connected to the discharge port of the buffer tank, and the discharge port of the preheater is connected to the heating concentrator.

[0017] The system for recovering phosphorus resources in calcium-magnesium solution as described above also includes a collecting tank and an evaporation discharge pump; the heating concentrator includes a first-effect heater, a first-effect separator, a second-effect heater and a second-effect separator;

[0018] The discharge port of the preheater is connected to the feed port of the first-effect heater;

[0019] The discharge port of the first-effect heater is connected to the feed port of the first-effect separator;

[0020] The discharge port of the first-effect separator is connected to the feed port of the second-effect heater;

[0021] The discharge port of the second-effect heater is connected to the feed port of the second-effect separator;

[0022] The discharge port of the secondary effect separator is connected to the feed port of the evaporation discharge pump;

[0023] The discharge port of the evaporation discharge pump is connected to the collecting tank.

[0024] In the system for recovering phosphorus resources in calcium-magnesium solution as described above, a first circulation pump is provided between the discharge port of the first-effect separator and the feed port of the first-effect heater.

[0025] In the system for recovering phosphorus resources in calcium-magnesium solution as described above, a second circulation pump is provided between the discharge port of the first-effect separator and the feed port of the second-effect heater.

[0026] In the system for recovering phosphorus resources in calcium-magnesium solution as described above, distributors are further provided between the ammonia water tank and the reaction tank, and between the lime milk tank and the reaction tank.

[0027] The beneficial effects of the utility model are:

[0028] Before the filtrate enters the heating concentrator, a reaction tank, an ammonia water tank and a lime milk tank are set up, so that the ammonia water, the decalcified filtrate and the lime milk generate phosphorus-containing precipitates in the reaction tank, and the phosphorus-containing precipitates and the filtrate after the reaction enter the filter press for solid-liquid separation, and the separated filtrate enters the heating concentrator for concentration, and the precipitate is recovered; therefore, the phosphorus content of the filtrate entering the heating concentrator is reduced, and the probability of solid precipitation in the heating concentrator is also reduced accordingly, which can avoid clogging of the heater and improve the recovery rate of phosphorus element. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0030] Figure 1 It is a structural schematic diagram of a system for recovering phosphorus resources in calcium and magnesium solution according to the utility model;

[0031] Figure 2 It is a schematic diagram of a system for recovering phosphorus resources in calcium and magnesium solution according to the utility model during operation;

[0032] The reference numerals are as follows:

[0033] 1-decalcification and magnesium filtrate tank, 2-reaction tank, 31-ammonia water tank, 32-lime milk tank, 4-filter press, 51-first effect heater, 52-first effect separator, 53-second effect heater, 54-second effect separator, 6-filter residue collection tank, 7-buffer tank, 8-preheater, 91-first circulation pump, 92-second circulation pump, 10-collection tank, 11-evaporation discharge pump. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the concept, specific structure and technical effects of the utility model in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the utility model. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the creation of the utility model can be combined interchangeably without conflicting with each other.

[0035] According to the record of Chinese patent CN112758972A: in the process of preparing the decalcified magnesium filtrate, potassium sulfate solution is reacted with ammonium calcium magnesium nitrate concentrated solution, calcium hydroxide powder is added for neutralization reaction, calcium sulfate solution is obtained, and filtered to obtain decalcified filtrate and calcium sulfate; due to the addition of calcium hydroxide powder, the decalcified magnesium filtrate contains a certain amount of calcium element, and the calcium element exists in the form of calcium nitrate with high solubility;

[0036] The technical problems existing in the current treatment of decalcified magnesium filtrate are as follows: the decalcified magnesium filtrate is pumped into the preheater, which is severely blocked after running for about 10 days; the first-effect heater is severely blocked after running for 10 days; the second-effect heater is severely blocked after running for 15 days; and there is scaling in the first-effect separator and the second-effect separator, which leads to scaling of the transfer pump outlet pipe under forced circulation conditions, small conveying volume, and low production load; research has found that the decalcified magnesium leaching solution contains a small amount of phosphorus. During the step-by-step concentration process of the second-effect countercurrent evaporation device, the leaching solution is gradually saturated, wherein the phosphorus element in the leaching slurry combines with the calcium element under acidic conditions, precipitates in the form of calcium hydrogen phosphate, and blocks the second-effect heater; on the one hand, the second-effect heater is blocked, affecting the concentration effect; on the other hand, the calcium hydrogen phosphate agglomerates in the second-effect heater, affecting the recovery of phosphorus element

[0037] Reference Figure 1 , Figure 2 , a system for recovering phosphorus resources in calcium and magnesium solution, comprising a decalcified magnesium filtrate tank 1, a reaction tank 2, an ammonia water tank 31, a lime milk tank 32, a filter press 4 and a heating concentrator;

[0038] The discharge port of the decalcified magnesium filtrate tank 1 is connected to the feed port of the reaction tank 2;

[0039] The discharge port of the ammonia water tank 31 is connected to the feed port of the reaction tank 2;

[0040] The discharge port of the lime milk tank 32 is connected to the feed port of the reaction tank 2;

[0041] The discharge port of the reaction tank 2 is connected to the feed port of the filter press 4;

[0042] The liquid outlet of the filter press 4 is connected to the feed inlet of the heating concentrator.

[0043] The decalcified magnesium filtrate tank 1 is used to receive and store the decalcified magnesium leaching solution after decalcified magnesium treatment, in preparation for subsequent phosphorus leaching.

[0044] Among them, the reaction tank 2 serves as the main place for chemical reaction to realize the leaching of phosphorus element; in the reaction tank 2, the decalcified magnesium leaching solution from the decalcified magnesium filtrate tank 1 is mixed with ammonia water from the ammonia water tank 31 and lime milk from the lime milk tank 32 to carry out precipitation reaction, so that the phosphorus element is converted into precipitate, which is convenient for subsequent separation and recovery.

[0045] The ammonia water tank 31 and the lime milk tank 32 store ammonia water and lime milk respectively, and provide necessary reagents for the precipitation reaction in the reaction tank 2 .

[0046] Among them, the working principle of the filter press 4 is to apply pressure to make the filtrate pass through the filter medium, while the phosphorus-containing precipitate is intercepted by the filter medium (such as filter cloth), thereby realizing solid-liquid separation; the filter press 4 in this embodiment is used to separate the phosphorus-containing precipitate and liquid produced after the reaction in the reaction tank 2, the phosphorus-containing precipitate is intercepted by the filter medium to form a phosphorus-containing filter cake, and the filtrate enters the heating concentrator.

[0047] The preparation steps of the decalcified magnesium filtrate in the decalcified magnesium filtrate tank 1 include: leaching phosphate rock with nitric acid; phosphorus element will be dissolved during the dilute nitric acid leaching process, and at the same time, the leaching solution of the phosphate rock leached with dilute nitric acid also contains phosphate ions, hydrogen ions and a small amount of calcium ions; in the reaction tank 2, the lime milk (mainly Ca(OH)2) and the hydroxide in the ammonia water neutralize the hydrogen ions in the decalcified magnesium leaching solution, and the lime milk provides calcium ions to react with the phosphate ions in the decalcified magnesium leaching solution. When the pH value in the reaction tank 2 reaches about 7, the reaction in the reaction tank 2 forms a calcium hydrogen phosphate precipitate (i.e., the phosphorus-containing precipitate mentioned above); after solid-liquid separation in the filter press 4, the phosphorus-containing precipitate is recovered to improve the recovery rate of phosphorus; the phosphorus content of the filtrate entering the heating concentrator is reduced, and the probability of solid precipitation in the heating concentrator is also reduced accordingly, so the heater can be avoided from being blocked.

[0048] Furthermore, a pH meter may be provided in the reaction tank 2 to detect the pH value in the reaction tank 2 .

[0049] Furthermore, the slag outlet of the filter press 4 is connected to a filter residue collecting tank 6. The filter residue collecting tank 6 is provided to facilitate the recovery of the phosphorus-containing precipitate separated in the filter press 4.

[0050] Furthermore, a filtrate pipe (not shown in the figure) is provided on the discharge port of the filter press 4, the filtrate pipe is connected to the heating concentrator, and a sight glass (not shown in the figure) is provided on the filtrate pipe. Diafiltration refers to the damage of the filter medium, and the filtrate discharged from the filter press 4 contains phosphorus-containing precipitates, which means that the filter press 4 has failed; by providing a sight glass on the filtrate pipe that can observe the situation in the filtrate pipe, it is possible to directly observe whether the filtrate in the filtrate pipe contains phosphorus-containing precipitates, thereby judging whether the filter press 4 has diafiltration, which is convenient for timely replacement of the filter medium.

[0051] Furthermore, the filtrate tube can be connected to the feed port of the reaction tank 2, and a switching valve (not shown in the figure) is arranged on the filtrate tube. When the filtration of the filter press 4 is observed through the sight glass, the control switch of the switching valve is turned to change the flow direction of the filtrate in the filtrate tube, so that the filtrate originally flowing to the heating concentrator flows back to the reaction tank 2, without affecting the operation of the reaction tank 2, while replacing the filter medium in the filter press 4; the switching valve is a prior art, and its other names include a three-way valve, a reversing valve or a conversion valve.

[0052] Furthermore, a stirrer is provided in the reaction tank 2. The stirrer is used to promote the uniform mixing of the decalcified magnesium leaching solution, ammonia water and lime milk in the reaction tank 2.

[0053] Furthermore, a buffer tank 7 is included, the feed port of the buffer tank 7 is connected to the liquid outlet of the filter press 4, and the discharge port of the buffer tank 7 is connected to the heating concentrator. The buffer tank 7 is used to temporarily store the filtrate obtained by filtering the filter press 4, so as to facilitate the filtrate to be transported to the heating concentrator according to the needs of the heating concentrator.

[0054] Specifically, it further comprises a preheater 8, the feed port of the preheater 8 is connected to the discharge port of the buffer tank 7, and the discharge port of the preheater 8 is connected to the heating concentrator. The function of the preheater 8 is to preheat the filtrate and provide suitable temperature conditions for the concentration of the filtrate.

[0055] More specifically, the system for recovering phosphorus resources in calcium-magnesium solution further includes a collecting tank 10 and an evaporation discharge pump 11; the heating concentrator includes a first-effect heater 51, a first-effect separator 52, a second-effect heater 53 and a second-effect separator 54;

[0056] The discharge port of the preheater 8 is connected to the feed port of the first-effect heater 51;

[0057] The discharge port of the first-effect heater 51 is connected to the feed port of the first-effect separator 52;

[0058] The discharge port of the first-effect separator 52 is connected to the feed port of the second-effect heater 53;

[0059] The discharge port of the second-effect heater 53 is connected to the feed port of the second-effect separator 54;

[0060] The discharge port of the secondary effect separator 54 is connected to the feed port of the evaporation discharge pump 11;

[0061] The discharge port of the evaporation discharge pump 11 is connected to the collecting tank 10 .

[0062] The main function of the first-effect heater 51 is to heat the filtrate and evaporate it. After the filtrate enters the first-effect heater 51, it absorbs heat, part of the solvent evaporates, and produces steam and concentrated liquid;

[0063] The function of the first-effect separator 54 is to separate the steam generated in the first-effect heater 51 from the remaining concentrated liquid, wherein the steam is separated and used for heating the second-effect heater 53, while the concentrated liquid can continue to flow to the second-effect heater 53;

[0064] The second-effect heater 53 is similar to the first-effect heater 51, and is used to further heat and evaporate the concentrated liquid after the first-effect separation to increase the concentration of the concentrated liquid; the second-effect separator 54 has a similar function to the first-effect separator 52, and is used to separate the new concentrated liquid and the new steam obtained after the second-effect heater 53 is heated.

[0065] More specifically, a first circulation pump 91 is provided between the discharge port of the first-effect separator 52 and the feed port of the first-effect heater 51. The first circulation pump 91 can keep the filtrate circulating in the first-effect separator 52 and the first-effect heater 51, which contributes to more uniform heat distribution and more efficient heat exchange, thereby improving the utilization efficiency of thermal energy.

[0066] More specifically, a second circulation pump 92 is provided between the discharge port of the first-effect separator 52 and the feed port of the second-effect heater 53. The second circulation pump 92 can promote the concentrated liquid to flow from the first-effect separator 52 to the second-effect heater 53.

[0067] Furthermore, a distributor is provided between the ammonia water tank 31 and the reaction tank 2, and between the lime milk tank 32 and the reaction tank 2; the provision of the distributor helps to evenly distribute the material flowing out of the ammonia water tank or the lime milk tank to the reaction tank, thereby improving the reaction efficiency.

[0068] The working process of this system is as follows:

[0069] The decalcified magnesium filtrate in the decalcified magnesium filtrate tank 1 enters the reaction tank 2, and the ammonia water in the ammonia water tank 31 and the lime emulsion in the lime emulsion tank 32 enter the reaction tank 2, and the pH value is adjusted to generate a precipitate and a filtrate in the reaction tank 2;

[0070] The precipitate and the filtrate enter the filter press 4 for filtration, wherein the phosphorus-containing precipitate is discharged into the filter residue collection tank 6, and the filtrate enters the buffer tank 7;

[0071] Filtrate flow direction:

[0072] The filtrate in the buffer tank 7 flows through the preheater 8 for preheating and then enters the first-effect heater 51, which heats the filtrate to form steam and concentrated liquid.

[0073] The primary separator 52 separates the steam and the condensate;

[0074] The first circulation pump 91 causes the concentrated liquid separated by the first-effect separator 52 to circulate into the first-effect heater 51 for re-concentration; after the circulation is completed, the steam separated by the first-effect separator 52 is used as the heat source of the second-effect heater 53, and the concentrated liquid separated by the first-effect separator 52 is pumped into the second-effect heater 53 through the second circulation pump 92;

[0075] The second-effect heater 53 heats the concentrated liquid to form new steam and new concentrated liquid;

[0076] The secondary separator 54 separates new steam and new concentrated liquid, wherein the new concentrated liquid flows through the evaporation discharge pump 11 and then flows into the collecting tank 10 .

[0077] By using the above-mentioned system for recovering phosphorus resources in calcium-magnesium solution, a phosphorus recovery rate of more than 95% in phosphate ore can be achieved.

[0078] The above is a specific description of the preferred implementation of the utility model, but the invention of the utility model is not limited to the described embodiments. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the utility model. These equivalent deformations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A system for recovering phosphorus resources in calcium and magnesium solution, characterized in that: It comprises a decalcified magnesium filtrate tank (1), a reaction tank (2), an ammonia water tank (31), a lime milk tank (32), a filter press (4) and a heating concentrator; The discharge port of the decalcified magnesium filtrate tank (1) is connected to the feed port of the reaction tank (2); The discharge port of the ammonia water tank (31) is connected to the feed port of the reaction tank (2); The discharge port of the lime milk tank (32) is connected to the feed port of the reaction tank (2); The discharge port of the reaction tank (2) is connected to the feed port of the filter press (4); The liquid outlet of the filter press (4) is connected to the feed inlet of the heating concentrator.

2. The system for recovering phosphorus resources in calcium and magnesium solution according to claim 1, characterized in that: The residue outlet of the filter press (4) is connected to a residue collecting tank (6).

3. The system for recovering phosphorus resources in calcium and magnesium solution according to claim 1, characterized in that: The discharge port of the filter press (4) is provided with a filtrate tube, the filtrate tube is connected to the heating concentrator, and the filtrate tube is provided with a sight glass.

4. The system for recovering phosphorus resources in calcium and magnesium solution according to claim 1, characterized in that: The reaction tank (2) is provided with a stirrer.

5. The system for recovering phosphorus resources in calcium and magnesium solution according to claim 1, characterized in that: It also comprises a buffer tank (7), the feed port of the buffer tank (7) is connected to the liquid outlet of the filter press (4), and the discharge port of the buffer tank (7) is connected to the heating concentrator.

6. The system for recovering phosphorus resources in calcium and magnesium solution as claimed in claim 5, characterized in that: It also includes a preheater (8), the feed port of the preheater (8) is connected to the discharge port of the buffer tank (7), and the discharge port of the preheater (8) is connected to the heating concentrator.

7. The system for recovering phosphorus resources in calcium and magnesium solution as claimed in claim 6, characterized in that: It also includes a collecting tank (10) and an evaporation discharge pump (11); the heating concentrator includes a first-effect heater (51), a first-effect separator (52), a second-effect heater (53) and a second-effect separator (54); The discharge port of the preheater (8) is connected to the feed port of the first-effect heater (51); The discharge port of the first-effect heater (51) is connected to the feed port of the first-effect separator (52); The discharge port of the first-effect separator (52) is connected to the feed port of the second-effect heater (53); The discharge port of the second-effect heater (53) is connected to the feed port of the second-effect separator (54); The discharge port of the secondary effect separator (54) is connected to the feed port of the evaporation discharge pump (11); The discharge port of the evaporation discharge pump (11) is connected to the collecting tank (10).

8. The system for recovering phosphorus resources in calcium and magnesium solution as claimed in claim 7, characterized in that: A first circulation pump (91) is provided between the discharge port of the first-effect separator (52) and the feed port of the first-effect heater (51).

9. The system for recovering phosphorus resources in calcium and magnesium solution as claimed in claim 7, characterized in that: A second circulation pump (92) is provided between the discharge port of the first-effect separator (52) and the feed port of the second-effect heater (53).

10. The system for recovering phosphorus resources in calcium and magnesium solution according to claim 1, characterized in that: Distributors are also provided between the ammonia water tank (31) and the reaction tank (2), and between the lime milk tank (32) and the reaction tank (2).

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