Adsorption coupling contact precipitation defluorination system and defluorination method

Abstract

The invention discloses an adsorption coupling contact precipitation defluorination system and a defluorination method, and the method comprises the following steps: feeding fluorine-containing mine water into a defluorination reaction tank, and carrying out adsorption defluorination on the fluorine-containing mine water through a defluorination filter material layer to obtain first defluorination mine water; feeding the calcium agent and the phosphorus agent according to the formula ratio into a fluorine removal reaction tank, removing fluorine through a catalytic reaction to obtain second fluorine-removed mine water, and then feeding the obtained second fluorine-removed mine water into a clean water tank; when the head loss of the second defluorination mine water exceeds a threshold value, feeding backwashing water and backwashing air into a defluorination reaction tank, and backwashing a filter material in a defluorination filter material layer; feeding the regenerated liquid into a defluorination reaction tank, soaking a defluorination filter material layer for 10-12 hours, and then discharging generated waste liquid into a lime reaction tank. According to the method disclosed by the invention, through adsorption, contact precipitation and regeneration, the carbon-based apatite adsorbed with fluorine ions in the defluorination reaction tank is used as a seed crystal for subsequent contact precipitation, so that the service time of a filter material in a defluorination filter material layer is effectively prolonged, and the regeneration frequency of the filter material is reduced.

Description

Technical Field

[0001] The patent of this invention belongs to the technical field of mine water treatment, and relates to the defluorination of mine water, and specifically to an adsorption coupled contact precipitation defluorination system and a defluorination method. Background Art

[0002] The mine water in coal mining areas mostly has a high fluoride content. Long-term intake of excessive fluoride will have a great impact on human health. Therefore, defluorination and improving water quality have become the key to improving water resource security in water-scarce mining areas. The commonly used defluorination methods in the prior art include adsorption and contact precipitation. Among them, the adsorption method uses hydroxyapatite or carbon-based apatite to remove fluoride ions in mine water. This process has the characteristics of excellent water quality, but because the pH of fluorine-containing mine water is 7.8-8.2, and the bicarbonate concentration therein exceeds 250 mg / L, it is necessary to first use acid to adjust the water quality to about 6.5. During the adjustment process, a large amount of acidic pH adjustment liquid is consumed, and it will continuously regenerate to produce alkaline solution that is very difficult to handle; although the contact precipitation method has the advantages of no need for chemical regeneration and no need to adjust pH, the calcium and phosphorus concentration of the produced water is high, which is not conducive to subsequent treatment, and it is easy to cause the total phosphorus in the drainage to exceed the standard, the water quality is unstable, and the regeneration cycle of the defluorination filter material is short.

[0003] To sum up, it is of great significance to combine the two processes in the mine water treatment process, effectively solve the above-mentioned defects of single process operation, and improve the protection and utilization of high-fluoride mine water resources. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an adsorption-coupled contact precipitation defluorination system and a defluorination method to solve the technical problems of short regeneration cycle and unstable water quality in the prior art mine water defluorination process.

[0005] In order to solve the above technical problems, this application adopts the following technical solutions:

[0006] An adsorption-coupled contact precipitation defluorination system, comprising a defluorination reaction tank and a lime reaction tank connected and arranged, a cushion layer is arranged at the bottom of the defluorination reaction tank, a defluorination filter layer is arranged on the cushion layer; a raw water inlet and a regeneration liquid inlet are arranged at a position above the defluorination filter layer in the defluorination reaction tank; a backwash water inlet and a water production port are opened at a position on the side wall of the defluorination reaction tank corresponding to the defluorination filter layer;

[0007] The raw water inlet is connected to a water inlet pipe; the regeneration liquid inlet is connected to a regeneration liquid storage tank via a regeneration liquid pipe; the backwash water inlet is connected to a backwash water pipe, the water outlet is connected to a lime reaction tank, and the water production port is connected to a clean water tank via a water production pipe.

[0008] The present invention also has the following technical features:

[0009] Specifically, the backwash water pipeline is connected to the air compressor and the clean water tank through a tee; the water inlet pipeline is also connected to a calcium agent storage tank and a phosphorus agent storage tank.

[0010] Furthermore, the defluorination filter material layer is filled with hydroxyapatite filter material.

[0011] Furthermore, a fluoride analyzer is provided on the water production pipeline.

[0012] The present invention also protects a method for removing fluorine by adsorption-coupled contact precipitation, which is implemented by the above-mentioned adsorption-coupled contact precipitation system and comprises the following steps:

[0013] Step 1, sending the fluorine-containing mine water into a defluorination reaction tank, and removing fluorine from the fluorine-containing mine water by adsorption through a defluorination filter layer to obtain first defluorinated mine water;

[0014] Step 2, sending the formulated amount of calcium agent and phosphorus agent into the defluorination reaction tank, removing fluorine through catalytic reaction to obtain second defluorinated mine water, and then sending the obtained second defluorinated mine water into the clear water tank;

[0015] Step 3: When the head loss of the second defluorination mine water exceeds a threshold value, backwash water and backwash air are sent into the defluorination reaction tank to backwash the filter material in the defluorination filter material layer;

[0016] Step 4: Send the regenerated liquid into the defluorination reaction tank to soak the defluorination filter material layer for 10 to 12 hours, and then discharge the generated waste liquid into the lime reaction tank.

[0017] Furthermore, the fluoride ion content of the first defluoridated mine water is 0.8-1.0 mg / L.

[0018] Furthermore, in step 2, the calcium agent is calcium chloride, the phosphorus agent is sodium dihydrogen phosphate, and the regeneration liquid is sodium hydroxide solution.

[0019] Furthermore, in the defluorination reaction tank, the atomic molar ratio of Ca:P:F is 5:3:1.

[0020] Furthermore, the backwashing time in step 3 is 5 to 10 minutes; in step 4, the amount of sodium hydroxide solution added is 0.5 to 1 times the weight of the filter material in the defluorination filter layer, and the concentration of the sodium hydroxide solution is 1 to 2%.

[0021] Furthermore, the threshold value in step 3 is 0.8-1.4 m.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] The adsorption-coupled contact precipitation defluorination system provided by the present invention has a simple structure and is easy to operate. The adsorption-coupled contact precipitation defluorination method uses adsorption-contact precipitation-regeneration, and uses the carbon-based apatite adsorbed with fluoride ions in the defluorination reaction tank as a seed for subsequent contact precipitation. It can effectively extend the use time of the filter material in the defluorination filter layer in the defluorination process, reduce the regeneration frequency of the filter material, and reduce the amount of pH regulator added while improving the water quality of the produced water, thereby ultimately improving the defluorination efficiency of mine water and reducing the defluorination cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the system of the present invention;

[0025] Figure 2 The corresponding relationship diagram of the fluorine concentration in the produced water and time in Application Example 1 and Comparative Example 1;

[0026] Figure 3 This is a graph showing the relationship between fluoride ions in produced water and influent pH in Comparative Example 2.

[0027] The symbols in the figure represent:

[0028] 1-fluorine removal reaction tank, 2-lime reaction tank, 3-water inlet pipe, 4-regeneration liquid pipe, 5-regeneration liquid storage tank, 6-backwash water pipe, 7-water production pipe, 8-clear water tank, 9-air compressor, 10-calcium agent storage tank, 11-phosphorus agent storage tank, 12-lime storage tank.

[0029] The specific contents of the present invention are further explained in detail below in conjunction with the drawings and embodiments. DETAILED DESCRIPTION

[0030] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0031] The terms "first", "second", and other ordinal numbers used in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include one or more of the features. Unless otherwise specified, the terms "installed", "connected", "connected", "fixed", and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0032] It should be noted that all raw materials in the present invention, unless otherwise specified, are raw materials known in the art.

[0033] The technical concept of the present invention is: through the adsorption-contact precipitation-regeneration scheme, the carbon-based apatite in the defluorination reaction tank that adsorbs fluoride ions in fluoride-containing mine water is used as the seed of subsequent contact precipitation, so as to effectively reduce the regeneration frequency of the filter material in the defluorination filter layer in the defluorination process, improve the water quality of the produced water, and reduce the amount of pH regulator added.

[0034] The technical terms involved in the present invention are explained below:

[0035] Head loss: the loss of mechanical energy per unit mass of liquid during the movement of water.

[0036] The scheme of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] Example 1

[0038] Following the above technical solution, Figure 1 As shown, this embodiment provides an adsorption-coupled contact precipitation defluorination system, comprising a defluorination reaction tank 1 and a lime reaction tank 2 connected and arranged, the lime reaction tank 2 is also connected to a lime storage tank 12, a cushion layer is arranged at the bottom of the defluorination reaction tank 1, and a defluorination filter material layer is arranged on the cushion layer; a raw water inlet and a regeneration liquid inlet are arranged at a position above the defluorination filter material layer in the defluorination reaction tank 1; a backwash water inlet and a water production port are opened at a position of the side wall of the defluorination reaction tank 1 corresponding to the defluorination filter material layer;

[0039] Among them, the defluorination reaction tank 1 is mainly used for defluorination of mine water and regeneration of defluorination filter layer. Among them, the removal of fluoride ions in the water body has two stages. The first stage is to adsorb fluoride ions by the filter material (such as hydroxyapatite) filled in the defluorination filter layer. The second stage is to add calcium agent (calcium chloride) and phosphorus agent (sodium dihydrogen phosphate) to react with fluoride ions in the mine water in the defluorination reaction tank 1 to obtain fluoroapatite, thereby further removing fluoride ions in the mine water. The lime reaction tank 2 is used to treat the waste liquid generated by backwashing and regeneration. The calcium ions in the lime react with the high concentration of fluoride ions in the waste liquid to generate calcium fluoride, thereby effectively reducing the fluoride ion concentration in the waste liquid.

[0040] The raw water inlet is connected to an inlet pipe 3; the regeneration liquid inlet is connected to a regeneration liquid storage tank 5 via a regeneration liquid pipe 4; the backwash water inlet is connected to a backwash water pipe 6, the outlet is connected to a lime reaction tank 2, and the water outlet is connected to a clean water tank 8 via a water production pipe 7.

[0041] As a preferred solution of this embodiment, the backwash water pipeline 6 is connected to the air compressor 9 and the clean water tank 8 through a tee; the water inlet pipeline 3 is also connected to a calcium agent storage tank 10 and a phosphorus agent storage tank 11. The air compressor 9 is used to send air into the backwash water pipeline 6, and the clean water tank 8 is used to store clean water, which can be sent into the backwash water pipeline 6.

[0042] As a preferred solution of this embodiment, the fluorine removal filter material layer is filled with hydroxyapatite filter material, wherein the hydroxyapatite filter material is commercially available and is used to adsorb fluoride ions in mine water.

[0043] As a preferred solution of this embodiment, a Hach CA610 online fluoride analyzer is provided on the water production pipeline 7 , and the fluoride analyzer is used to monitor the fluoride ion content of the water produced in the water production pipeline 7 in real time.

[0044] When the present invention is in use: fluorine-containing mine water enters the defluorination reaction tank 1 through gravity flow or a raw water pump, the filter material in the defluorination filter material layer in the defluorination reaction tank adsorbs fluoride ions to produce the first defluorination mine water, when the fluoride ion concentration is monitored to be close to 1 mg / L, calcium agent and phosphorus agent are added to the defluorination reaction tank 1 to enter the contact precipitation defluorination stage, when the head loss exceeds 0.8 to 1.4 m during gravity flow, clean water and air are introduced into the defluorination reaction tank 1, the filter material is dispersed by steam and water, and the suspended matter on the filter material is removed; then, regeneration liquid (NaOH solution) is added to the defluorination reaction tank 1 to react with the filter material to achieve regeneration of the filter material; finally, the high-fluorine waste liquid generated after backwashing and regeneration enters the lime reaction tank 2.

[0045] Example 2

[0046] This embodiment discloses a method for removing fluorine by coupled contact precipitation, which is implemented by the adsorption coupled contact precipitation system disclosed in Example 1, and includes the following steps:

[0047] Step 1, sending the fluorine-containing mine water into a defluorination reaction tank, and removing fluorine from the fluorine-containing mine water by adsorption through a defluorination filter layer to obtain first defluorinated mine water;

[0048] After the fluorine-containing mine water comes into contact with the active hydroxyapatite defluorination filter material, a dual reaction of adsorption and ion exchange occurs on the filter material surface, that is, the fluoride ions in the fluorine-containing mine water are adsorbed on the filter material, and the fluoride ions also react with the OH on the filter material surface. — Ions are exchanged.

[0049] Ca 10 (PO4)6(OH)2+2F - →Ca 10 (PO4)6F2+2OH -

[0050] Ca 10(PO4)6(OH)2+F - →Ca 10 (PO4)6F(OH)+2OH -

[0051] Among them, the fluoride ion content of the first defluoridation mine water is 0.8-1.0 mg / L.

[0052] Step 2, sending the formulated amount of calcium agent and phosphorus agent into the defluorination reaction tank, removing fluorine through catalytic reaction to obtain second defluorinated mine water, and then sending the obtained second defluorinated mine water into the clear water tank;

[0053] Preferably, the calcium agent is calcium chloride, the phosphorus agent is sodium dihydrogen phosphate, and calcium fluorophosphate converted from hydroxyapatite filter material serves as an inducing crystal. Fluoride ions, calcium chloride and sodium dihydrogen phosphate react to form fluorapatite. The dosage is based on the atomic stoichiometric ratio of calcium, phosphorus and fluorine in fluorapatite Ca10(PO4)6F2. In terms of atomic molar ratio, Ca:P:F=5:3:1.

[0054] Step 3: When the head loss of the second defluorination mine water exceeds the threshold, the backwash water and backwash air are sent into the defluorination reaction tank to backwash the filter material in the defluorination filter layer; a steam-water mixture is used for backwashing for 5-10 minutes to disperse the filter material and keep it in a loose state, and then chemical regeneration is performed.

[0055] In this embodiment, the head loss is measured by the existing gravity flow method: when the liquid level in the gravity flow reactor rises to a certain position, the head loss is measured with the help of a liquid level meter.

[0056] Step 4: Send the regenerated liquid into the defluorination reaction tank to soak the defluorination filter material layer for 10 to 12 hours, and then discharge the generated waste liquid into the lime reaction tank.

[0057] The regeneration liquid used in this embodiment is a sodium hydroxide solution (NaOH effective concentration is 1%, i.e. 10000 mg / L), and the amount of sodium hydroxide solution added is 0.5 to 1 times the weight of the filter material in the defluorination filter material layer, and 500L-1000L of 1% sodium hydroxide solution is used for one ton of filter material. The regeneration liquid can be added at one time or in batches, and the batch addition specifically includes: closing the defluorination tank water inlet valve, backwashing with raw water for 5 to 10 minutes; adding the regeneration liquid at a rate of 2 to 4m per hour increase in the liquid level in the defluorination reaction tank, slowly injecting about 30 to 35% of the regeneration liquid, and soaking for 4 hours; adding the regeneration liquid at a rate of 2 to 4m per hour increase in the liquid level in the defluorination reaction tank, slowly injecting about 30% of the regeneration liquid, and soaking for 4 hours; adding the remaining regeneration liquid to the defluorination reaction tank.

[0058] Application Example 1

[0059] In this application example, the adsorption coupled contact precipitation defluorination system disclosed in Example 1 and the adsorption coupled contact precipitation defluorination method disclosed in Example 2 are used to treat fluorine-containing mine water. The fluoride ion concentration of the fluorine-containing mine water is 2.5 mg / L, the bicarbonate concentration is 513 mg / L, the pH of the influent is 8.1, and the filter material is the spherical CHAP drinking water defluorination filter material produced by Henan Yanglin Environmental Protection Technology Co., Ltd. The added calcium agent and phosphorus agent are shown in the following table: Calcium chloride and sodium dihydrogen phosphate are added at an atomic molar ratio of Ca:P:F=5:3:1.

[0060] After testing, the final pH of the produced water was 7.1, and no further pH adjustment was required. During the water production process, the fluoride ion content of the produced water was monitored. The monitoring results are as follows: Figure 2 shown.

[0061] Since the induced defluoridation effect is stable, the fluoride ion content in the produced water is less than 1 mg / L for more than 150 hours, indicating that the adsorption coupled contact precipitation defluoridation method provided by the present invention can significantly reduce the regeneration frequency of the filter material, thereby greatly reducing the defluoridation cost.

[0062] The processing process of this embodiment is as follows Figure 3 As shown, Figure 3 There are two regeneration cycles, from which it can be seen that each cycle will enter the contact precipitation defluorination stage after the rapid adsorption stage. Among them, the turning point between the rapid adsorption stage and the contact precipitation defluorination stage is the addition of calcium and phosphorus agents. The defluorination effect of contact precipitation occurs instantaneously, and its defluorination effect can run stably for more than 100 hours. The adsorption stage of the first cycle is longer than that of the second cycle, and the contact precipitation defluorination stage accounts for a larger proportion in the second cycle. The adsorption-coupled contact precipitation defluorination process runs stably, and the fluoride ion concentration in the produced water can be controlled below 1 mg / L. The specific monitoring values ​​are shown in Table 1.

[0063]

[0064]

[0065] Table 1. Fluoride ion concentration monitoring values

[0066] Comparative Example 1

[0067] The fluorine-containing mine water used in this comparative example is the same as that in Application Example 1, except that this comparative example adopts a direct adsorption process, and monitors the fluorine ion content of the produced water during the water production process. The monitoring results are shown in FIG. Figure 2 shown.

[0068] from Figure 2It can be seen that, using the direct adsorption process, after 50 hours, the fluoride ion content in the produced water begins to exceed 1 mg / L, and as time goes by, the fluoride ion content continues to increase, indicating that after 50 hours, the adsorption effect of the filter layer can no longer meet the requirements and needs to be regenerated. However, using the coupled contact precipitation defluorination method provided by the present invention, the fluoride ion concentration in the produced water can be controlled below 1 mg / L for a long time, and the defluorination effect can be stably operated for more than 100 hours.

[0069] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. An adsorption-coupled contact precipitation defluorination system, characterized in that: The invention comprises a defluorination reaction tank (1) and a lime reaction tank (2) which are connected and arranged, wherein a cushion layer is arranged at the bottom of the defluorination reaction tank (1), and a defluorination filter material layer is arranged on the cushion layer; a raw water inlet and a regeneration liquid inlet are arranged at a position above the defluorination filter material layer in the defluorination reaction tank (1); a backwash water inlet and a water production port are arranged at a position on the side wall of the defluorination reaction tank (1) corresponding to the defluorination filter material layer; The raw water inlet is connected to a water inlet pipe (3); the regeneration liquid inlet is connected to a regeneration liquid storage tank (5) via a regeneration liquid pipe (4); the backwash water inlet is connected to a backwash water pipe (6); the water outlet is connected to a lime reaction tank (2); and the water production port is connected to a clean water tank (8) via a water production pipe (7).

2. The adsorption-coupled contact precipitation defluorination system according to claim 1, characterized in that: The backwash water pipeline (6) is connected to the air compressor (9) and the clean water tank (8) via a tee; the water inlet pipeline (3) is also connected to a calcium agent storage tank (10) and a phosphorus agent storage tank (11).

3. The adsorption-coupled contact precipitation defluorination system according to claim 1, characterized in that: The defluorination filter material layer is filled with hydroxyapatite filter material.

4. The adsorption-coupled contact precipitation defluorination system according to claim 1, characterized in that: A fluoride analyzer is provided on the water production pipeline (7).

5. A method for defluorination by adsorption-coupled contact precipitation, characterized in that: The method is implemented by the adsorption coupled contact precipitation system according to any one of claims 1 to 4, comprising the following steps: Step 1, sending the fluorine-containing mine water into a defluorination reaction tank, and removing fluorine from the fluorine-containing mine water by adsorption through a defluorination filter layer to obtain first defluorinated mine water; Step 2, sending the formulated amount of calcium agent and phosphorus agent into the defluorination reaction tank, removing fluorine through catalytic reaction to obtain second defluorinated mine water, and then sending the obtained second defluorinated mine water into the clear water tank; Step 3: When the head loss of the second defluorination mine water exceeds a threshold value, backwash water and backwash air are sent into the defluorination reaction tank to backwash the filter material in the defluorination filter material layer; Step 4: Send the regenerated liquid into the defluorination reaction tank to soak the defluorination filter material layer for 10 to 12 hours, and then discharge the generated waste liquid into the lime reaction tank.

6. The defluorination method by adsorption-coupled contact precipitation as claimed in claim 5, characterized in that: The fluoride ion content of the first defluoridated mine water is 0.8-1.0 mg / L.

7. The defluorination method by adsorption-coupled contact precipitation as claimed in claim 5, characterized in that: In step 2, the calcium agent is calcium chloride, the phosphorus agent is sodium dihydrogen phosphate, and the regeneration liquid is sodium hydroxide solution.

8. The defluorination method by adsorption-coupled contact precipitation as claimed in claim 5, characterized in that: In the step 2, the atomic molar ratio of Ca:P:F in the defluorination reaction tank is 5:3:

1.

9. The defluorination method by adsorption-coupled contact precipitation as claimed in claim 7, characterized in that: The backwashing time in step 3 is 5 to 10 minutes; in step 4, the amount of sodium hydroxide solution added is 0.5 to 1 times the weight of the filter material in the defluorination filter layer, and the concentration of the sodium hydroxide solution is 1 to 2%.

10. The defluorination method by adsorption-coupled contact precipitation as claimed in claim 5, characterized in that: The threshold value in step 3 is 0.8 to 1.4 m.

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