Graphite purification wastewater treatment device and wastewater treatment method thereof

Abstract

Graphite purification wastewater treatment device and wastewater treatment method thereof, the present invention is to solve the problems that the fluoride in the effluent of the existing graphite purification wastewater treatment process cannot stably meet the standard and a large amount of hazardous waste is generated. In the graphite purification wastewater treatment device of the present invention, a raw water tank, a lime clarifier, a vertical flow sedimentation tank, a first intermediate water tank, a secondary reaction tank and a second intermediate water tank are arranged in sequence along the water flow direction, and solid lime reagent is added to the lime clarifier, wherein the secondary reaction tank is separated into a first dosing area, a second dosing area and a sedimentation area in sequence by a partition, and the effluent of the second intermediate water tank passes through an activated alumina filter bed unit and a resin adsorption unit in sequence. The chloride in the graphite purification wastewater of the present invention is 4080 mg / L, and after treatment, the chloride in the effluent is less than 100 mg / L; the fluoride in the inlet is 4050 mg / L, and after treatment, the fluoride content is less than 5 mg / L.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment, and in particular relates to a graphite purification wastewater treatment device and a wastewater treatment method thereof. Background Art

[0002] Graphite is an important resource of non-metallic minerals. Graphite has good properties such as corrosion resistance, radiation resistance, electrical conductivity, thermal conductivity, self-lubrication, and high and low temperature resistance.

[0003] Graphite ore is processed into graphite materials, and it must be purified technically first. The components of graphite raw materials include fixed carbon, volatile phenols, ash and other substances. The content of fixed carbon determines the quality of graphite. 50-75% is low-carbon graphite, 80-93% is medium-carbon graphite, 94-99% is high-carbon graphite, and 99.9% or more is high-purity graphite. The quality of graphite purification determines the use characteristics and comprehensive performance of graphite materials. The higher the purity of graphite, the higher the application value. Whether it is used as raw materials for artificial diamonds, cathode materials for lithium-ion batteries, bipolar materials for fuel cells, expanded graphite materials for sealing and heat conduction, or special graphite materials for aerospace, national defense, and nuclear industries, the purity of graphite is required to be 99% to 99.99% carbon, or even higher. Therefore, graphite purification is the premise and basis for the expansion and application of graphite materials.

[0004] The main methods for graphite purification include the following (Table 1): (1) Flotation method, which has low equipment requirements and low energy consumption, but the purity of purification is limited, and the carbon content of the product is mostly 80%-90%; (2) Alkali acid method has strong versatility, low equipment investment, and high graphite grade, which can reach 99%-99.9%, but it consumes a lot of energy, has serious equipment corrosion, and has a long process flow; (3) Hydrofluoric acid method, which has low production cost and the carbon content of the product is 99%-99.9%, but hydrofluoric acid is highly toxic and has a serious impact on the environment; (4) Chlorination roasting method, which has high efficiency and the carbon content of the product is about 98%, but the operating equipment is complex, the product purity is limited, the stability is poor, and it causes serious pollution to the environment; (5) High temperature method produces products with a carbon content of 99.99% or above, but the treatment method needs to be specially designed according to the raw materials and the specific conditions of the factory, but the one-time investment is large and the energy consumption is large.

[0005] Table 1: Comparative analysis of graphite purification methods

[0006]

[0007]

[0008] For economic and practical considerations, companies usually adopt the hydrofluoric acid method, which adds a large amount of hydrofluoric acid to dissolve silicates, silicon dioxide, etc. in the ore, and adds strong acids such as sulfuric acid, hydrochloric acid, and nitric acid at the same time, thus producing a lot of high-concentration acidic fluoride-containing wastewater.

[0009] At present, most enterprises use the direct lime addition method to treat fluoride-containing wastewater. It is difficult for the fluoride content of graphite purification wastewater to reach the standard (<10mg / L) stably (Comprehensive Wastewater Discharge Standard GB8978-1996). Graphite purification wastewater has become the main source of environmental pollution. The problem of graphite factory wastewater pollution control has become an urgent problem that needs to be solved in the development of the graphite industry. Summary of the invention

[0010] The purpose of the present invention is to solve the problems that the fluoride in the effluent of the existing graphite purification wastewater treatment process cannot stably meet the standards and a large amount of hazardous waste is generated, and to provide a graphite purification wastewater treatment device and a wastewater treatment method thereof.

[0011] The graphite purification wastewater treatment device of the present invention comprises a lime clarifier, a vertical flow sedimentation tank, a first intermediate water tank, a secondary reaction tank, a second intermediate water tank, an activated alumina filter bed unit and a resin adsorption unit. A raw water tank, a lime clarifier, a vertical flow sedimentation tank, a first intermediate water tank, a secondary reaction tank and a second intermediate water tank are sequentially arranged along the water flow direction. Each tank body (tank body) is connected by a water pipe. Solid lime reagent is added to the lime clarifier. The secondary reaction tank is sequentially divided into a first dosing area, a second dosing area and a sedimentation area by a partition. PAC flocculant is added to the first dosing area, and stone is added to the second dosing area. Gray water (calcium hydroxide aqueous solution), an inclined plate assembly is arranged in the sedimentation zone, a sludge discharge port is opened at the bottom of the sedimentation zone, one end of the return mud pipe is connected to the sludge discharge port of the sedimentation zone, and the other end of the return mud pipe is connected to the lime clarification tank, the outlet water of the second intermediate water tank is connected to the water inlet of the activated alumina filter bed unit through pipeline No. 1, the activated alumina filter bed unit is composed of two parallel activated alumina filter beds, the outlet water of the activated alumina filter bed unit is connected to the water inlet of the resin adsorption unit through pipeline No. 2, the resin adsorption unit is composed of two parallel resin adsorbers, and the outlet water of the resin adsorption unit is discharged through the drain pipe.

[0012] The graphite purification wastewater treatment method of the present invention is implemented according to the following steps:

[0013] 1. The graphite purification wastewater in the raw water tank flows into the lime clarification tank, solid lime reagent is added to the lime clarification tank, and stirred for reaction for 20min to 30min to obtain primary treated wastewater;

[0014] 2. The primary treated wastewater flows into the vertical flow sedimentation tank, and the hydraulic retention time is controlled to be 15min-25min. The supernatant flows into the first intermediate water tank, and the effluent of the first intermediate water tank flows into the secondary reaction tank. PAC flocculant is added to the first dosing area of ​​the secondary reaction tank, and lime water is added to the second dosing area. The reaction is stirred in the first dosing area and the second dosing area for 30-40min. The wastewater flows into the sedimentation area for mud and water separation, and the mud residue is returned to the lime clarification tank through the mud return pipe to obtain the secondary treated wastewater;

[0015] 3. The secondary treated wastewater flows into the second intermediate water tank. The effluent from the second intermediate water tank flows into the activated alumina filter bed unit through pipeline No. 1. The effluent from the activated alumina filter bed unit flows into the resin adsorption unit through pipeline No. 2. The effluent from the resin adsorption unit completes the treatment of graphite purification wastewater.

[0016] The graphite purification wastewater treatment device and wastewater treatment method of the present invention adopt multi-stage chemical coagulation and precipitation. Lime reagent is added in the first reaction tank. Lime is dissolved in water to generate calcium hydroxide, which reacts with fluoride ions in wastewater to generate calcium fluoride. The calcium fluoride is in a gel-like state. The calcium fluoride floccules flocculate and precipitate. However, due to the influence of anions such as chloride, sulfate and nitrate in the wastewater, the effluent quality will be unstable. The present invention continues to add PAC flocculant and lime water in the secondary reaction tank. Fluoride ions are flocculated and precipitated by aluminum salt coagulant. Lime water reacts with fluoride ions to generate CaF2. The crystal grains of CaF2 obtained at this time are small and the purity is high. CaF2 powder (fluorite powder) can be directly collected to achieve the purpose of waste utilization and reduction. The mud residue in the precipitation zone of the secondary reaction tank is returned to the lime clarification tank through the mud return pipe. The fine mud residue is returned to the lime clarification tank as flocculation crystal nucleus, which accelerates the coagulation reaction and reduces the dosage of lime reagent. The present invention finally uses activated alumina filter bed and resin adsorption for deep treatment.

[0017] The graphite purification wastewater treatment device and wastewater treatment method of the present invention include the following beneficial effects:

[0018] 1. The present invention adopts multi-stage chemical coagulation and precipitation to remove a large amount of fluoride ions. After chemical treatment, the fluoride ion concentration is about 20 mg / L, which does not meet the discharge standard "Comprehensive Sewage Discharge Standard" (GB8978-1996) (fluoride ion concentration <10 mg / L). Therefore, the present invention adopts activated alumina filter bed and resin adsorption deep treatment in the process, and the fluoride ion concentration is <5 mg / L, realizing efficient removal and efficient desalination of fluoride. After treatment, the fluoride of the graphite purification wastewater of the present invention is stably up to the standard.

[0019] 2. Adopt a new high-purity graphite wastewater treatment process, optimize the treatment process parameters, precipitate and reflow the sludge generated in the secondary reaction tank, reduce the dosage of reagents, and the CaF2 precipitate produced in the secondary reaction tank can be used as fluorite powder.

[0020] 3. The processing capacity of the graphite purification wastewater treatment device of the present invention is 60L / h. The chloride content of the graphite purification wastewater inlet is 4080mg / L. After treatment, the chloride content of the effluent is less than 100mg / L; the fluoride content of the inlet is 4050mg / L. After treatment, the fluoride content is less than 5mg / L. The graphite purification wastewater treatment system of the present invention is stable and has low operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the graphite purification wastewater treatment device of the present invention. DETAILED DESCRIPTION

[0022] Specific implementation method 1: The graphite purification wastewater treatment device in this implementation method includes a lime clarification tank 1, a vertical flow sedimentation tank 2, a first intermediate water tank 3, a secondary reaction tank 4, a second intermediate water tank 5, an activated alumina filter bed unit 6 and a resin adsorption unit 7. A raw water tank 8, a lime clarification tank 1, a vertical flow sedimentation tank 2, a first intermediate water tank 3, a secondary reaction tank 4 and a second intermediate water tank 5 are arranged in sequence along the water flow direction. Each tank body (tank body) is connected by a water pipe. Solid lime reagent is added to the lime clarification tank 1, wherein the secondary reaction tank 4 is separated into a first dosing area 4-1, a second dosing area 4-2 and a sedimentation area 4-3 by a partition, a PAC flocculant is added to the first dosing area 4-1, and a PAC flocculant is added to the second dosing area 4 -2, an inclined plate assembly is provided in the sedimentation zone 4-3, a sludge discharge port is provided at the bottom of the sedimentation zone 4-3, one end of the mud return pipe 13 is connected to the mud discharge port of the sedimentation zone 4-3, and the other end of the mud return pipe 13 is connected to the lime clarification tank 1, and the outlet water of the second intermediate water tank 5 is connected to the water inlet of the activated alumina filter bed unit 6 through the No. 1 pipeline 10, the activated alumina filter bed unit 6 is composed of two parallel activated alumina filter beds, and the outlet water of the activated alumina filter bed unit 6 is connected to the water inlet of the resin adsorption unit 7 through the No. 2 pipeline 11, the resin adsorption unit 7 is composed of two parallel resin adsorbers, and the outlet water of the resin adsorption unit 7 is discharged through the drain pipe 12.

[0023] In the secondary reaction tank 4 of this embodiment, the first dosing area 4-1, the second dosing area 4-2 and the precipitation area 4-3 are connected.

[0024] In this embodiment, if the effluent from the activated alumina filter bed unit meets the standards, it can be discharged directly without passing through the resin adsorption unit.

[0025] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that an agitator is provided in the lime clarification tank 1 and a mud discharge port is provided at the bottom of the lime clarification tank 1 .

[0026] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that a mud discharge port is provided at the bottom of the vertical flow sedimentation tank 2 .

[0027] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that a stirrer is provided in the first dosing area 4-1 and the second dosing area 4-2 in the secondary reaction tank 4.

[0028] Specific embodiment 5: This embodiment is different from specific embodiments 1 to 4 in that the graphite purification wastewater treatment device also includes a backwash water tank 9, and the water outlet of the backwash water tank 9 is connected to the backwash inlet at the bottom of the activated alumina filter bed unit 6 through a backwash water pipe 14.

[0029] Specific embodiment 6: This embodiment is different from specific embodiment 5 in that a backwash drain port is opened on the top of the activated alumina filter bed unit 6 , one end of the backwash return pipe 15 is connected to the backwash drain port, and the other end of the backwash return pipe 15 is connected to the raw water tank 8 .

[0030] Specific implementation method 7: This implementation method is different from any one of specific implementation methods 1 to 6 in that the mass concentration of the lime water is 10%.

[0031] Specific embodiment 8: The graphite purification wastewater treatment method of this embodiment is implemented according to the following steps:

[0032] 1. The graphite purified wastewater in the raw water tank 8 flows into the lime clarification tank 1, solid lime reagent is added to the lime clarification tank 1, and stirred for reaction for 20min to 30min to obtain primary treated wastewater;

[0033] 2. The primary treated wastewater flows into the vertical flow sedimentation tank 2, and the hydraulic retention time is controlled to be 15min-25min. The supernatant flows into the first intermediate water tank 3. The effluent of the first intermediate water tank 3 flows into the secondary reaction tank 4. PAC flocculant is added to the first dosing zone 4-1 of the secondary reaction tank 4, and lime water is added to the second dosing zone 4-2. The reaction is stirred in the first dosing zone 4-1 and the second dosing zone 4-2 for 30-40min. The wastewater flows into the sedimentation zone 4-3 for mud and water separation. The mud residue is returned to the lime clarification tank 1 through the mud return pipe 13 to obtain the secondary treated wastewater;

[0034] 3. The secondary treated wastewater flows into the second intermediate water tank 5, the outlet water of the second intermediate water tank 5 flows into the activated alumina filter bed unit 6 through the No. 1 pipeline 10, the outlet water of the activated alumina filter bed unit 6 flows into the resin adsorption unit 7 through the No. 2 pipeline 11, and the outlet water of the resin adsorption unit 7 completes the treatment of the graphite purification wastewater.

[0035] Specific embodiment 9: This embodiment is different from specific embodiment 8 in that the stirring reaction in step 1 is controlled for 24 min to 30 min.

[0036] Specific implementation method ten: The difference between this implementation method and specific implementation method eight is that in step two, the hydraulic retention time of the sedimentation zone 4-3 is controlled to be 30 to 40 minutes.

[0037] Specific embodiment eleven: This embodiment is different from specific embodiment eight in that when the fluoride content in the graphite purification wastewater in the raw water tank 8 is 3600-5000 mg / L, the dosage of solid lime reagent in the lime clarification tank 1 is 6g-7.5g per liter of wastewater, the dosage of PAC flocculant in the secondary reaction tank 4 is 1.5g-2.0g per liter of wastewater, and the dosage of lime water in the secondary reaction tank 4 is 1.5g-2.5g per liter of wastewater (calculated as calcium hydroxide in lime water).

[0038] Embodiment: In this embodiment, the method for treating wastewater using the graphite purification wastewater treatment device described in the first embodiment is implemented according to the following steps:

[0039] 1. The graphite purified wastewater in the raw water tank 8 flows into the lime clarification tank 1, and solid lime reagent is added to the lime clarification tank 1. The amount of solid lime reagent added is 7.5g / L (calculated as calcium hydroxide), and the reaction is stirred for 24 minutes to obtain primary treated wastewater;

[0040] Second, the primary treated wastewater flows into the vertical flow sedimentation tank 2, and the hydraulic retention time is controlled to be 15 minutes. The supernatant flows into the first intermediate water tank 3, and the effluent of the first intermediate water tank 3 flows into the secondary reaction tank 4. PAC flocculant is added to the first dosing zone 4-1 of the secondary reaction tank 4, and the dosage of PAC flocculant is 0.5g / L. Lime water is added to the second dosing zone 4-2, and the dosage of lime water is 2g / L (calculated as calcium hydroxide). The first dosing zone 4-1 and the second dosing zone 4-2 are stirred for reaction for 30 minutes, and the wastewater flows into the sedimentation zone 4-3 for mud and water separation. The hydraulic retention time of the sedimentation zone 4-3 is controlled to be 30 minutes. The mud residue is returned to the lime clarification tank 1 through the mud return pipe 13 to obtain secondary treated wastewater;

[0041] 3. The secondary treated wastewater flows into the second intermediate water tank 5, the outlet water of the second intermediate water tank 5 flows into the activated alumina filter bed unit 6 through the No. 1 pipeline 10, the outlet water of the activated alumina filter bed unit 6 flows into the defluorination resin adsorption unit 7 through the No. 2 pipeline 11, and the outlet water of the defluorination resin adsorption unit 7 completes the treatment of the graphite purification wastewater.

[0042] The graphite purification wastewater in this embodiment belongs to the production process wastewater with high salinity, high concentration and harmful to the environment, which is difficult to treat. The treatment capacity of the graphite purification wastewater treatment device in this embodiment is 60L / h. The height of the activated alumina aluminum bed filter material layer in this embodiment is 1000mm, the diameter of the activated alumina filter bed is 200mm, and the overall height of the activated alumina filter bed is 1600mm. The resin adsorption layer in the resin adsorber is 1000mm high, the diameter of the adsorber is 200mm, and the overall height of the resin adsorber is 1600mm. The volume of the lime clarification tank 1 is 24L, the volume of the vertical flow sedimentation tank 2 is 15L, the volume of the dosing zone in the secondary reaction tank 4 is 30L, and the volume of the sedimentation zone is 30L. The fluoride ion content of the effluent from the vertical flow sedimentation tank 2 is about 100mg / L, and the fluoride ion content of the effluent from the secondary reaction tank 4 is less than 20mg / L.

[0043] The water quality of the graphite purification wastewater in this example and the water quality of the treated effluent are shown in Table 1 below.

[0044] Table 1

[0045]

[0046] The present invention realizes that the effluent meets the water quality standard requirements of the industrial wastewater reuse index "Water Quality for Industrial Water Use in Urban Wastewater Recycling" (GB / T19923-2005), and at the same time meets the characteristic index of fluoride concentration being lower than 5 mg / L.

Claims

1. Graphite purification wastewater treatment device, characterized in that The graphite purification wastewater treatment device comprises a lime clarification tank (1), a vertical flow sedimentation tank (2), a first intermediate water tank (3), a secondary reaction tank (4), a second intermediate water tank (5), an activated alumina filter bed unit (6) and a resin adsorption unit (7). A raw water tank (8), a lime clarification tank (1), a vertical flow sedimentation tank (2), a first intermediate water tank (3), a secondary reaction tank (4) and a second intermediate water tank (5) are sequentially arranged along the water flow direction. Each tank body is connected by a water pipe. Solid lime reagent is added to the lime clarification tank (1). The secondary reaction tank (4) is sequentially divided into a first dosing area (4-1), a second dosing area (4-2) and a sedimentation area (4-3) by a partition. PAC flocculant is added to the first dosing area (4-1), and stone is added to the second dosing area (4-2). The mass concentration of the gray water and lime water is 10%. An inclined plate assembly is provided in the sedimentation zone (4-3). A mud discharge port is provided at the bottom of the sedimentation zone (4-3). One end of the mud return pipe (13) is connected to the mud discharge port of the sedimentation zone (4-3). The other end of the mud return pipe (13) is connected to the lime clarification tank (1). The outlet water of the second intermediate water tank (5) is connected to the water inlet of the activated alumina filter bed unit (6) through a No. 1 pipeline (10). The activated alumina filter bed unit (6) is composed of two parallel activated alumina filter beds. The outlet water of the activated alumina filter bed unit (6) is connected to the water inlet of the resin adsorption unit (7) through a No. 2 pipeline (11). The resin adsorption unit (7) is composed of two parallel resin adsorbers. The outlet water of the resin adsorption unit (7) is discharged through a drain pipe (12).

2. The graphite purification wastewater treatment device according to claim 1, characterized in that A stirrer is arranged in the lime clarification tank (1), and a mud discharge port is opened at the bottom of the lime clarification tank (1).

3. The graphite purification wastewater treatment device according to claim 1, characterized in that A mud discharge port is provided at the bottom of the vertical flow sedimentation tank (2).

4. The graphite purification wastewater treatment device according to claim 1, characterized in that Agitators are provided in the first dosing zone (4-1) and the second dosing zone (4-2) in the secondary reaction tank (4).

5. The graphite purification wastewater treatment device according to claim 1, characterized in that The graphite purification wastewater treatment device also includes a backwash water tank (9), the water outlet of the backwash water tank (9) is connected to the backwash inlet at the bottom of the activated alumina filter bed unit (6) through a backwash water pipe (14).

6. The graphite purification wastewater treatment device according to claim 5, characterized in that A backwash drain outlet is provided on the top of the activated alumina filter bed unit (6), one end of the backwash return pipe (15) is connected to the backwash drain outlet, and the other end of the backwash return pipe (15) is connected to the raw water tank (8).

7. A method for treating graphite purification wastewater using the graphite purification wastewater treatment device as claimed in claim 1, characterized in that The graphite purification wastewater treatment method is implemented according to the following steps:

1. The graphite purified wastewater in the raw water tank (8) flows into the lime clarification tank (1), solid lime reagent is added to the lime clarification tank (1), and the reaction is stirred for 20 minutes to 30 minutes to obtain primary treated wastewater; 2. The primary treated wastewater flows into the vertical flow sedimentation tank (2), and the hydraulic retention time is controlled to be 15 minutes to 25 minutes. The supernatant flows into the first intermediate water tank (3). The effluent of the first intermediate water tank (3) flows into the secondary reaction tank (4). PAC flocculant is added to the first dosing zone (4-1) of the secondary reaction tank (4), and lime water is added to the second dosing zone (4-2). The first dosing zone (4-1) and the second dosing zone (4-2) are stirred for reaction for 30 to 40 minutes. The wastewater flows into the sedimentation zone (4-3) for mud and water separation. The mud residue is returned to the lime clarification tank (1) through the mud return pipe (13) to obtain secondary treated wastewater.

3. The secondary treated wastewater flows into the second intermediate water tank (5), the outlet water of the second intermediate water tank (5) flows into the activated alumina filter bed unit (6) through the No. 1 pipeline (10), the outlet water of the activated alumina filter bed unit (6) flows into the resin adsorption unit (7) through the No. 2 pipeline (11), and the outlet water of the resin adsorption unit (7) completes the treatment of the graphite purification wastewater.

8. The method for treating graphite purification wastewater according to claim 7, characterized in that In step 1, the stirring reaction is controlled for 24 min to 30 min.

9. The method for treating graphite purification wastewater according to claim 7, characterized in that Step 2: Control the hydraulic retention time of the sedimentation zone (4-3) to 30 to 40 minutes.

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