TWI731678B - Method and device for treating molybdenum-containing wastewater and recovering iron molybdate crystals - Google Patents

Abstract

The present invention is a method for treating molybdenum-containing wastewater and recovering iron molybdate crystallization. It includes: (1) injecting molybdenum-containing wastewater into a first reaction tank, adding a trivalent iron ion agent into the first reaction tank, and Add an acid agent to adjust the appropriate pH; (2) Inject the molybdenum-containing wastewater in the first reaction tank into the second reaction tank, and add an alkali agent to the second reaction tank to make the molybdenum ions in the molybdenum-containing wastewater and The iron ions react to produce iron molybdate crystalline components and adhere to the surface of the crystalline substrate. The wastewater treated by the second reaction tank can overflow from the upper end of the second reaction tank, and define the overflow from the upper end of the second reaction tank Wastewater is treated water; (3) The treated water is diverted into the subsequent treatment program, part of the treated water flows into circulating water, and the circulating water is diverted into the second reaction tank, so that the residual iron molybdate crystalline components in the circulating water can be regenerated Attach and accumulate on the surface of the crystalline substrate; (4) When the accumulated iron molybdate crystals on the surface of the crystalline substrate in the second reaction tank are adhered to a certain particle size, then the surface can be attached to the surface of the crystalline substrate with iron molybdate crystals The particles are taken out from the second reaction tank to achieve the purpose of treatment of molybdenum-containing wastewater and recycling of molybdenum metal resources.

Description

Method and device for treating molybdenum-containing wastewater and recovering iron molybdate crystals

The present invention is a method and device for treating molybdenum-containing wastewater and recovering iron molybdate crystals, especially a method and device that can provide a low iron addition, effectively and stably remove molybdenum ions in the wastewater, and produce crystals containing In order to achieve the method and device for the treatment of molybdenum-containing wastewater and the recycling of molybdenum metal resources.

In many industrial manufacturing processes, heavy metal waste water containing molybdenum will be discharged. For example, the etching of the array segment in the manufacturing process of TFT-LCD in the optoelectronic industry will discharge high concentration of heavy metal waste water containing molybdenum (Molybdenum); The pickling process in the production process will also produce molybdenum-containing heavy metal wastewater. At present, the common methods for the treatment of molybdenum-containing wastewater include the use of ion-exchange resin (Ion-exchange Resin) adsorption and chemical coagulation (Chemical Coagulation). Among them, if the ion-exchange resin adsorption method is used for treatment, the treatment process will still produce The molybdenum-containing regeneration wastewater still needs to be chemically treated with high concentrations of molybdenum contained in the regeneration wastewater, which will cause high operating costs. Moreover, if the chemical coagulation method is used for treatment, the main reaction is to add trivalent iron salt and control Proper pH to produce iron molybdate precipitates, but in practice, it is necessary to add iron ions that are many times higher than the theoretical iron-molybdenum ratio to meet the discharge water standard, which will increase the use cost of iron salt reagents and chemical A large amount of sludge will be formed in the process of coagulation method, which will increase the cost of subsequent sludge dewatering and sludge cake treatment.

The purpose of the present invention is to improve the shortcomings of the above-mentioned conventional molybdenum-containing wastewater treatment methods, and to provide a method for effectively and stably removing molybdenum ions in the wastewater with a lower amount of iron added, and to produce ferric molybdate-containing state The crystalline particles of the ingredients can be used to treat molybdenum-containing wastewater and recover molybdenum metal resources and reuse methods and devices.

In order to achieve the above objective, the method for treating and recycling molybdenum-containing wastewater containing iron molybdate crystallization of the present invention includes the following steps:

(1) Drain the molybdenum-containing wastewater discharged by the production unit into the first reaction tank for storage, and add an acid agent to the first reaction tank to adjust the pH of the molybdenum-containing wastewater in the first reaction tank to be less than 3.0, and in the first reaction tank A trivalent iron ion agent is injected into a reaction tank, so that the molybdenum ions and iron ions in the molybdenum-containing wastewater in the first reaction tank are dissolved.

(2) Drain the molybdenum-containing wastewater (pH>3.0) in the first reaction tank into the second reaction tank, and fill the second reaction tank with an appropriate amount of crystalline substrate so that the crystalline substrate is in the second reaction tank Fluidizing, and adding an alkali agent in the second reaction tank to control the pH of the molybdenum-containing wastewater in the second reaction tank to 3～5, so that the molybdenum ions in the molybdenum-containing wastewater react with iron ions to form iron molybdate crystalline components , And make the iron molybdate crystalline component adhere to the surface of the crystalline substrate, and the waste water after being treated by the second reaction tank can overflow from the upper end of the second reaction tank, and define the waste water overflowing from the upper end of the second reaction tank as Treat water.

(3) The treated water can be drained into the subsequent treatment process, and part of the treated water will flow into circulating water. The circulating water can be drained into the second reaction tank, while monitoring the pH of the treated water, and based on the measured treated water Inject an appropriate amount of alkaline agent into the second reaction tank to control the pH of the molybdenum-containing wastewater in the second reaction tank to 3 to 5, so that the residual iron molybdate crystalline components in the circulating water can reattach and accumulate on the crystalline base.材surface.

(4) When the accumulated iron molybdate crystals on the surface of the crystalline substrate in the second reaction tank reach particles of a certain size, the crystalline substrate particles will be deposited on the bottom of the second reaction tank. At this time, part of the crystalline substrate can be removed. The material particles are taken out from the second reaction tank, and at the same time an appropriate amount of new crystalline base material is added to achieve the purpose of treatment of molybdenum-containing wastewater and recycling of molybdenum metal resources.

In view of the above, another feasible embodiment is to add a proper dose of ferric ion agent to the circulating water, and then mix the circulating water and the molybdenum-containing wastewater (pH>3.0) in the first reaction tank into the second reaction. Slot.

Based on the above, another feasible embodiment is to add an appropriate amount of ferric ion agent to the molybdenum-containing wastewater (pH>3.0) in the first reaction tank and the circulating water at the same time, and then the circulating water and the first reaction The molybdenum-containing wastewater (pH>3.0) in the tank is mixed and drawn into the second reaction tank.

The above molybdenum-containing wastewater treatment and recovery iron molybdate crystallization method can be implemented by the following molybdenum-containing wastewater treatment and recovery iron molybdate crystallization device, which includes:

The first reaction tank can provide injection and storage of molybdenum-containing wastewater discharged by the production unit. The first reaction tank is equipped with a pH detection unit, the first reaction tank is equipped with a water delivery pipe, and the water delivery pipe is equipped with a water delivery pump. .

The second reaction tank is a fluidized bed. The second reaction tank is filled with an appropriate amount of crystalline substrate. The bottom of the second reaction tank is provided with a water inlet port, and the top of the second reaction tank is provided with a water outlet port. The water outlet port is provided with a water outlet pipe, the water outlet pipe is provided with a pH detection unit, the water outlet pipe is provided with a return pipe connected with the water inlet port, the return pipe is provided with a circulating pump, and the return pipe interacts with the first reaction The water pipe of the tank is connected.

The acid agent injection unit is provided with an agent injection conduit which is communicated with the first reaction tank.

The iron ion medicament injection unit is provided with a medicament injection conduit communicated with the first reaction tank.

The alkali agent injection unit is provided with a drug injection conduit connected with the second reaction tank.

In view of the above, another feasible embodiment is that the iron ion drug injection unit is provided with a drug injection conduit connected to the return pipe of the second reaction tank.

Based on the above, another feasible embodiment is in which the iron ion medicine injection unit is provided with a medicine injection pipe which is respectively connected with the return pipes of the first reaction tank and the second reaction tank.

Thereby, it provides a method for effectively and stably removing molybdenum ions in wastewater with a low iron addition, and producing crystalline particles containing ferric molybdate, so as to achieve the treatment of molybdenum-containing wastewater and the recycling of molybdenum metal resources.的方法和装置。 Method and device.

Regarding the technical means and structure used by the present invention to achieve the purpose, I would like to cooperate with the embodiment shown in FIG. 1, and the detailed description is as follows:

The method for treating molybdenum-containing wastewater and recovering crystallization containing iron molybdate of the present invention, as shown in FIG. 1, includes the following steps:

(1) Drain the molybdenum-containing wastewater discharged by the production unit into the first reaction tank 10 for storage, and monitor the pH of the molybdenum-containing wastewater in the first reaction tank. If the pH of the molybdenum-containing wastewater in the first reaction tank is greater than 3.0, An acid agent (such as HCl, H ₂ SO _4, etc.) is added to the first reaction tank to adjust the pH of the molybdenum-containing wastewater in the first reaction tank to be less than 3.0, and a trivalent iron ion agent (Fe ^{3 +} ), so that the molybdenum ions and iron ions in the molybdenum-containing wastewater are dissolved.

(2) Drain the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 into the second reaction tank 20. The second reaction tank 20 is a fluidized bed, and the second reaction tank 20 is filled with an appropriate amount The crystalline substrate 60 (such as: quartz sand, anthracite, activated carbon, iron molybdate particles, iron hydroxide particles, ... etc.), so that the crystalline substrate 60 fluidized in the second reaction tank 20, and in the second An alkali agent (such as sodium hydroxide (NaOH) or calcium hydroxide Ca(OH) ₂ )) is added to the reaction tank 20 to control the pH of the molybdenum-containing wastewater in the second reaction tank 20 to 3 to 5, so that the molybdenum-containing wastewater The molybdenum ions and iron ions react to form iron molybdate (Fe ₂ (MoO ₄ ) ₃ ) crystalline components, and the iron molybdate (Fe ₂ (MoO ₄ ) ₃ ) crystalline components are attached to the second reaction tank 20 The surface of the crystalline substrate 60 in the second reaction tank 20, and the waste water treated by the second reaction tank 20 can overflow from the outlet port 22 at the upper end of the second reaction tank 20, and define the waste water overflowing from the outlet port 22 at the upper end of the second reaction tank 20 For processing water 70.

(3) The treated water 70 can be drained into the subsequent processing procedures (for example: solid-liquid separation procedures, since the subsequent processing procedures are not the focus of the present invention, so no further description), part of the treated water 70 is divided into circulation Water 80, the circulating water 80 and the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 are mixed and drained into the second reaction tank 20, and the pH of the treated water 70 is monitored, based on the measured pH of the treated water 70 A proper amount of alkali agent is injected into the second reaction tank 20 to control the pH of the molybdenum-containing wastewater in the second reaction tank 20 to 3 to 5, so that the residual iron molybdate (Fe ₂ (MoO _{4 ) 3} ) in the circulating water 80 ) The crystalline component can reattach and accumulate on the surface of the crystalline substrate 60 in the second reaction tank 20.

_{(4) When the accumulated iron molybdate (Fe 2} (MoO ₄ ) ₃ ) crystals adhere to the surface of the crystalline substrate 60 in the second reaction tank 20 reach a certain particle size, the particles of the crystalline substrate 60 will be deposited in the second reaction At the bottom of the tank 20, at this time, part of the crystalline substrate 60 particles can be taken out of the second reaction tank 20, and at the same time, an appropriate amount of new crystalline substrate 60 can be supplemented to achieve the treatment of molybdenum-containing wastewater and the recycling of molybdenum metal resources. purpose.

In view of the above, another feasible embodiment, as shown in Figure 2, is to add a proper dose of ferric ion medicament (Fe ^{3+) to the circulating water 80, and then combine it} with the molybdenum-containing wastewater in the first reaction tank 10 (pH>3.0) The mixed drainage is injected into the second reaction tank 60.

In view of the above, another feasible embodiment, as shown in Fig. 3, is to add an appropriate amount of ferric ion agent to the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 and the circulating water 80 at the same time. (Fe ³⁺ ), the circulating water 80 and the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 are mixed and drawn into the second reaction tank 60.

In view of the above, another feasible embodiment, as shown in FIG. 4, is that the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 can be injected into the second reaction tank 60 without being mixed with the circulating water 80, but It is directly injected into the second reaction tank 20.

The above-mentioned molybdenum-containing wastewater treatment and recovery of iron molybdate crystallization method can be implemented by the following device, as shown in FIG. 1, which includes a first reaction tank 10, a second reaction tank 20, an acid injection unit 30, and iron ions A medicament injection unit 40 and an alkali agent injection unit 50; among them:

The first reaction tank 10 (please also refer to Fig. 1) is capable of injecting and storing molybdenum-containing wastewater discharged by the production unit. The first reaction tank 10 is provided with a pH detection unit 11, and the first reaction tank 10 is provided with There is a water delivery pipe 12 which is provided with a water delivery pump 13.

The second reaction tank 20 (shown in Figure 1) is a fluidized bed. The second reaction tank 20 is filled with an appropriate amount of crystalline substrate 60 (such as quartz sand, anthracite, activated carbon, iron molybdate particles). , Iron hydroxide particles,... etc.), the second reaction tank 20 is provided with a water inlet port 21 at the bottom, the second reaction tank 20 is provided with a water outlet port 22 at the top, and the water outlet port 22 is provided with a water outlet pipe 23, the water outlet pipe 23 is provided with a pH detection unit 24, the outlet pipe 23 is provided with a return pipe 25 communicating with the water inlet port 21, the return pipe 25 is provided with a circulation pump 26, and the return pipe 25 is connected to the first reaction tank 10 The water pipe 12 communicates with each other.

The acid injection unit 30 (as shown in FIG. 1) is connected to the first reaction tank 10 by a drug injection conduit 31.

The iron ion medicine injection unit 40 (as shown in FIG. 1) is connected to the first reaction tank 10 by a medicine injection conduit 41.

The alkali injection unit 50 (as shown in FIG. 1) is connected to the second reaction tank 20 by a pharmaceutical injection conduit 51.

With the above device, as shown in FIG. 1, the pH detection unit 11 provided on the first reaction tank 10 can monitor the pH of the molybdenum-containing wastewater in the first reaction tank 10, and the pH of the molybdenum-containing wastewater in the first reaction tank 10 can be monitored according to the pH detection unit 11 To obtain the pH, control the acid agent injection unit 30 to inject an appropriate amount of acid agent into the first reaction tank 10 through the agent injection pipe 31 to adjust the pH of the molybdenum-containing wastewater in the first reaction tank 10 to be less than 3.0, and use the iron ion agent The injection unit 40 injects an appropriate amount of trivalent iron ion agent (Fe ³⁺ ) into the first reaction tank 10 through the agent injection pipe 41 to make the molybdenum ions and iron ions in the molybdenum-containing wastewater into a dissolved state.

Then, the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 is drained by the water delivery pump 13 through the water delivery pipe 12 and the return pipe 25, and is stably injected into the second reaction tank 20 from the water inlet 21. And the crystalline substrate 60 in the second reaction tank 20 is fluidized.

At the same time, the alkali agent injection unit 50 injects an appropriate amount of alkali agent (such as sodium hydroxide (NaOH) or calcium hydroxide Ca(OH) ₂ ) into the second reaction tank 20 through the agent injection pipe 51 to control the first The pH of the molybdenum-containing wastewater in the second reaction tank 20 is 3 to 5, so that the molybdenum ions and iron ions of the molybdenum-containing wastewater in the second reaction tank 20 form iron molybdate (Fe ₂ (MoO ₄ ) ₃ ) crystalline components, and the molybdenum The crystalline component of ferric acid (Fe ₂ (MoO ₄ ) ₃ ) can adhere and accumulate on the surface of the crystalline substrate 60 in the second reaction tank 20 to form ferric molybdate crystals.

Then, the wastewater treated by the second reaction tank 20 can overflow from the outlet port 22 at the upper end of the second reaction tank 20, and the wastewater overflowing from the outlet port 22 is defined as the treated water 70, which can pass through the outlet pipe 23 Drain the flow into the subsequent processing procedure (for example: solid-liquid separation procedure, since this subsequent processing procedure is not the focus of the present invention, so no further description); part of the treated water 70 is divided into circulating water 80, and the circulating water 80 is used The circulating pump 26 draws and flows through the return pipe 25, and stably injects it into the second reaction tank 20 from the water inlet 21. At the same time, the pH detection unit 24 provided on the outlet pipe 23 at the upper end of the second reaction tank 20 can monitor the treated water. According to the pH of the treated water 70 measured by the pH detection unit 24, an appropriate amount of alkaline agent is injected into the second reaction tank 20 to adjust and control the pH of the molybdenum-containing wastewater in the second reaction tank 20 to 3. ~5, so that the _{crystalline components of iron molybdate (Fe 2} (MoO ₄ ) ₃ ) remaining in the circulating water 80 can re-attach and accumulate on the surface of the crystalline substrate 60 in the second reaction tank 20.

Continue to wait until the surface of the crystalline substrate 60 in the second reaction tank 20 is adhered and accumulated iron molybdate (Fe ₂ (MoO ₄ ) ₃ ) crystals reach a certain particle size, the crystalline substrate 60 particles will be deposited in the second reaction tank 20 At the bottom, at this time, part of the crystalline substrate 60 particles can be taken out of the second reaction tank 20, and an appropriate amount of new crystalline substrate 60 can be supplemented to achieve the purpose of treatment of molybdenum-containing wastewater and recycling of molybdenum metal resources.

In view of the above, another feasible embodiment, as shown in FIG. 2, is that the drug injection conduit 41 of the iron ion drug injection unit 40 may not be connected to the first reaction tank 10, but can be directly connected to the backflow of the second reaction tank 20 The pipe 25 is connected; the iron ion agent injection unit 40 can inject an appropriate amount of ferric ion agent (Fe ³⁺ ) into the return pipe 25 through the agent injection pipe 41, and the circulating water 80 flowing through the return pipe 25 can be It is mixed with the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 and then injected into the second reaction tank 60.

In view of the above, another feasible embodiment, as shown in FIG. 3, is that the drug injection conduit 41 of the iron ion drug injection unit 40 can be connected to the return pipe 25 of the first reaction tank 10 and the second reaction tank 20 at the same time. With the iron ion agent injection unit 40, an appropriate amount of trivalent iron ion agent (Fe ³⁺ ) can be injected into the first reaction tank 10 and the injection return pipe 25 through the agent injection pipe 41, respectively, and circulate through the return pipe 25 The water 80 can be mixed with the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 and then injected into the second reaction tank 60.

In view of the above, another feasible embodiment, as shown in Fig. 4, is that the molybdenum-containing wastewater (pH>3.0) in the first reaction tank 10 can be pumped by the water delivery pump 13 and directly drained through the water delivery pipe 12. The water port 21 is stably injected into the second reaction tank 20.

With the above-mentioned molybdenum-containing wastewater treatment and recovery iron molybdate crystallization method and device, the present invention mainly uses the second reaction tank 20 as a fluidized bed reactor, and puts an appropriate amount of crystalline substrate 60 into the second reaction tank 20, and controls Proper pH of the molybdenum-containing wastewater in the first reaction tank 10 and the second reaction tank 20, and design proper alkali agent injection unit 50 and iron ion agent injection unit 40 dosing point positions, and design appropriate return pipe 25 and circulation The water flow rate of 80 can make the molybdenum ions in the wastewater react with the added iron ions to form iron molybdate crystalline components at a low iron addition (low iron-molybdenum ratio), which can be deposited and accumulated in the second reaction tank 20 According to the actual measurement results, when the molybdenum ion concentration of the molybdenum-containing wastewater is 5-50mg/L, the removal rate of molybdenum ion can reach more than 95%, and it can meet the requirement that the molybdenum ion content is less than The discharge water quality standard of 0.6mg/L; at the same time, the present invention can effectively and stably remove molybdenum ions in the waste water and reach the discharge water standard, and the produced iron molybdate crystal particles do not need to go through the sludge dehydration process. The recycling of molybdenum metal resources can further effectively reduce the cost of molybdenum-containing wastewater treatment and improve the overall operating efficiency.

Therefore, it can be seen from the above that the molybdenum-containing wastewater treatment and recovery iron molybdate crystallization method and device of the present invention can effectively remove molybdenum in the molybdenum-containing wastewater and recover the molybdenum metal resources for reuse purposes; , This invention clearly has significant progress, and its method and device are indeed unprecedented, and sincerely it has met the requirements of an invention patent. Yan filed a patent application in accordance with the law, and prayed for the patent as a prayer.

However, the foregoing is only a feasible embodiment of the present invention. This embodiment is mainly used to illustrate the technical means and structure used by the present invention to achieve the purpose, and therefore cannot be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the specification of the present invention and the scope of the patent application shall still fall within the scope of protection covered by the present invention.

10: The first reaction tank 11: pH detection unit 12: Water pipe 13: water pump 20: Second reaction tank 21: Water inlet port 22: Outlet port 23: Outlet pipe 24: pH detection unit 25: Return pipe 26: Circulation pump 30: Acid injection unit 31: Medicament injection catheter 40: Iron ion agent injection unit 41: Medicament injection catheter 50: Alkali agent injection unit 51: Medicine injection catheter 60: Crystalline substrate 70: Treated water 80: Circulating water

[Figure 1] is a schematic diagram of an embodiment of the molybdenum-containing wastewater treatment method and device of the present invention. [Fig. 2] is a schematic diagram of another possible embodiment of the medicine injection catheter of the iron ion medicine injection unit of the present invention. [Fig. 3] is a schematic diagram of another possible embodiment of the medicine injection catheter of the iron ion medicine injection unit of the present invention. [Figure 4] is a schematic diagram of another feasible embodiment of the water delivery pipe of the first reaction tank in the method and device for treating molybdenum-containing wastewater of the present invention.

10: The first reaction tank

11: pH detection unit

12: Water pipe

13: water pump

20: Second reaction tank

21: Water inlet port

22: Outlet port

23: Outlet pipe

24: pH detection unit

25: Return pipe

26: Circulation pump

30: Acid injection unit

31: Medicament injection catheter

40: Iron ion agent injection unit

41: Medicament injection catheter

50: Alkali agent injection unit

51: Medicine injection catheter

60: Crystalline substrate

70: Treated water

80: Circulating water

Claims (8)

A method for treating molybdenum-containing wastewater and recovering crystallization of iron-containing molybdate includes the following steps: (1) Drain the molybdenum-containing wastewater discharged by the production unit into the first reaction tank for storage, monitor the pH of the molybdenum-containing wastewater in the first reaction tank, and add an appropriate amount of acid in the first reaction tank to adjust the first reaction tank. The pH of the molybdenum-containing wastewater in the reaction tank is less than 3.0, and a trivalent iron ion agent is injected into the first reaction tank, so that the molybdenum ions and iron ions of the molybdenum-containing wastewater in the first reaction tank are dissolved; (2) Drain the molybdenum-containing wastewater (pH>3.0) in the first reaction tank into the second reaction tank, and fill the second reaction tank with an appropriate amount of crystalline substrate so that the crystalline substrate is in the second reaction tank Fluidizing, and adding an alkali agent in the second reaction tank to control the pH of the molybdenum-containing wastewater in the second reaction tank to 3 to 5, so that the molybdenum ions in the molybdenum-containing wastewater react with iron ions to form iron molybdate crystalline components, And make the iron molybdate crystalline component adhere to the surface of the crystalline substrate, and the waste water after being treated by the second reaction tank can overflow from the upper end of the second reaction tank, and define the waste water overflowing from the upper end of the second reaction tank as treatment water; (3) The treated water can be drained into the subsequent treatment process, and part of the treated water flows into circulating water. The circulating water and the molybdenum-containing wastewater (pH>3.0) in the first reaction tank are mixed and drained into the second reaction tank. And monitor the pH of the treated water, and according to the measured pH of the treated water, inject an appropriate amount of alkaline agent into the second reaction tank to control the pH of the molybdenum-containing wastewater in the second reaction tank to 3 to 5, so that the residual in the circulating water The crystalline components of iron molybdate can be deposited and accumulated on the surface of the crystalline substrate in the second reaction tank; (4) When the accumulated iron molybdate crystals on the surface of the crystalline substrate in the second reaction tank reach particles of a certain size, the crystalline substrate particles will be deposited on the bottom of the second reaction tank. At this time, part of the crystalline substrate can be removed. The material particles are taken out from the second reaction tank, and at the same time, an appropriate amount of new crystalline substrate is supplemented to achieve the purpose of treatment of molybdenum-containing wastewater and recycling of molybdenum metal resources. According to the method for treating molybdenum-containing wastewater and recovering iron molybdate crystallization as described in claim 1, an appropriate amount of trivalent iron ion agent can be added to the circulating water. The method for treating molybdenum-containing wastewater and recovering iron molybdate crystallization as described in claim 1, which can simultaneously add an appropriate amount of trivalent iron ion agent to the molybdenum-containing wastewater (pH>3.0) in the first reaction tank and the circulating water . The method for treating molybdenum-containing wastewater and recovering iron molybdate crystallization according to claim 1, wherein the molybdenum-containing wastewater (pH>3.0) in the first reaction tank may not be mixed with circulating water and injected into the second reaction tank. Inject directly into the second reaction tank. A device for treating and recycling iron molybdate crystallization containing molybdenum wastewater includes a first reaction tank, a second reaction tank, an acid agent injection unit, an iron ion agent injection unit, and an alkali agent injection unit; wherein: The first reaction tank can provide injection and storage of molybdenum-containing wastewater discharged by the production unit. The first reaction tank is equipped with a pH detection unit, the first reaction tank is equipped with a water delivery pipe, and the water delivery pipe is equipped with a water delivery pump. ； The second reaction tank is a fluidized bed. The second reaction tank is filled with an appropriate amount of crystalline substrate. The bottom of the second reaction tank is provided with a water inlet port, and the top of the second reaction tank is provided with a water outlet port. The water outlet port is provided with a water outlet pipe, the water outlet pipe is provided with a pH detection unit, the water outlet pipe is provided with a return pipe connected with the water inlet port, the return pipe is provided with a circulating pump, and the return pipe interacts with the first reaction The water pipe of the tank is connected; The acid injection unit is communicated with the first reaction tank by a drug injection conduit; The iron ion medicine injection unit is connected with the first reaction tank by a medicine injection conduit; The alkali agent injection unit is connected with the second reaction tank by a drug injection conduit. The molybdenum-containing wastewater treatment and recovery iron molybdate crystallization device according to claim 5, wherein the agent injection pipe of the iron ion agent injection unit may not be connected to the first reaction tank, but directly connected to the second reaction tank. The return pipe of the tank is connected. The molybdenum-containing wastewater treatment and recovery iron molybdate crystallization device according to claim 5, wherein the agent injection pipe of the iron ion agent injection unit can be connected to the return pipes of the first reaction tank and the second reaction tank at the same time. The molybdenum-containing wastewater treatment and recovery iron molybdate crystallization device described in claim 5, wherein the molybdenum-containing wastewater in the first reaction tank can be pumped by a water delivery pump and directly drained through a water delivery pipe, and injected stably from the water inlet port In the second reaction tank.

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