Disc filtration and washing device, graphite purification device and purification method

Abstract

A disc filtration and washing device, a graphite purification device, and a purification method are disclosed. The device includes a material tank, a turntable, an auxiliary dewatering device, and a discharge device. The turntable includes a frame, a rotating shaft mounted on the frame, a motor driving the shaft, and multiple sets of filter plates fixed to the shaft and arranged axially along the shaft. Adjacent filter plates have air-permeable holes evenly distributed on opposite sides to form an adsorption side. The turntable, along the rotation direction of the shaft, sequentially includes a material adsorption zone, a first atomizing washing zone, a second atomizing washing zone, a compression dewatering zone, and a discharge zone. The turntable is installed directly above the material tank, placing the material adsorption zone within the tank. Atomizing spray devices are installed in both the first and second atomizing washing zones. An auxiliary dewatering device is installed in the compression dewatering zone, and a discharge device is installed in the discharge zone. This invention offers good washing effect, high washing efficiency, labor savings, and cost reduction.

Description

Technical Field

[0001] This invention relates to the field of graphite purification technology, and in particular to a disc filter washing device, a graphite purification device, and a purification method. Background Technology

[0002] As the lithium battery market continues to expand, competition is intensifying, leading to increasingly stringent control over material costs. Purification is a common wet purification process that, under liquid-phase conditions, allows acids and alkalis to react with and separate from metals, achieving purification. This process is widely used in hydrometallurgy, carbon black purification, natural graphite purification, hard carbon purification, recycled graphite, porous carbon, and activated carbon. Carbon black is a conductive agent in lithium-ion batteries, while natural graphite, hard carbon, recycled graphite, and porous carbon can serve as anode materials for lithium-ion batteries. Therefore, purification is one of the key steps in the manufacturing process of lithium battery materials.

[0003] There are many patents related to graphite purification, and the mainstream purification processes include the high-temperature method, the alkali-acid method, and the hydrofluoric acid method. The high-temperature method requires significant investment and is costly, yet some impurities remain. The alkali-acid and hydrofluoric acid methods involve long purification times, poor washing effects, difficulty in increasing production capacity, large equipment investments, and reliance on manual labor in production lines, leading to increased labor costs and product quality issues. Two patent documents, CN110171825A and CN202111033032, describe graphite purification processes that utilize filter presses for deacidification treatment after primary and secondary reactions.

[0004] like Figure 1 As shown, the existing process is as follows:

[0005] 1. The existing process technology involves adding graphite raw materials, tretinoin, benzoic acid, benzoic acid, and water to a mixing tank in specific proportions and stirring thoroughly.

[0006] 2. Use a pump to pump the stirred material into a primary reaction tank, and heat the material with steam. The reaction time is 16-24 hours, and the temperature is between 50-90℃. The temperature is continuously increased until the reaction is completed.

[0007] 3. After the reaction is completed, the material is separated into solid and liquid by a filter press and then washed with pure water. The washing time is 30-60 minutes. It takes 3 hours to wash one plate of material each time, and 2 tons of material are washed each time. The process is time-consuming, inefficient, and has a low yield, which seriously restricts the output.

[0008] 4. After dehydration, the material is fed into a secondary mixing tank. Acid A, acid B and water are added in proportion for a secondary reaction. The reaction takes 8-16 hours. The material is heated with steam, and the temperature is controlled between 50-90℃. The temperature is circulated and increased until the reaction is complete.

[0009] 5. After the secondary reaction is completed, the solid and liquid are separated again using a filter press and then washed for 30-60 minutes until the pH value is neutral. The mixture is then transferred to a third batching tank for pulping.

[0010] 6. After pulping, the pulp is pumped into the transition tank and then flows into the centrifuge for washing. The washing time is 40-80 minutes. After washing, the pulp is dehydrated to keep the moisture content ≤20%. After washing, the pulp is peeled off and bagged.

[0011] 7. After bagging, the material enters the flash evaporation process for drying and dehydration, and then undergoes sieving, demagnetization, and packaging.

[0012] Therefore, it can be seen that the existing graphite purification process has the following disadvantages:

[0013] 1. Long material reaction time results in low production efficiency;

[0014] 2. Large amounts of acid are used, resulting in a large amount of acidic wastewater and high wastewater treatment costs;

[0015] 3. The filter press washing equipment is outdated, with low automation, slow feeding, long washing time, large water consumption, and low efficiency. A production line with an annual output of 20,000 tons requires 5 filter presses, and 2 of them require 3 people to work and shovel materials, resulting in high labor costs.

[0016] 4. The output of a single 1600-type centrifuge is low, with a daily capacity of only 7 tons. A production line with an annual output of 20,000 tons requires 10 centrifuges, resulting in high equipment investment, high maintenance costs, low yield, low automation, and 2 employees required for 3 centrifuges, resulting in high labor costs.

[0017] 5. Due to the structure of the equipment, the material is located between two filter plates, which makes it impossible to effectively wash out impurity ions during washing. Therefore, a centrifuge is required for two washing processes to meet the quality requirements. Summary of the Invention

[0018] This invention addresses the shortcomings of existing technologies by providing a disc filter washing device, a graphite purification device, and a purification method that offer superior washing performance, high washing efficiency, labor savings, and cost reduction.

[0019] To achieve the above objectives, the present invention first proposes a disc filtration and washing device, including a material tank, a turntable, an auxiliary dewatering device, and a discharge device. The turntable includes a frame, a rotating shaft mounted on the frame, a motor driving the rotating shaft, and multiple sets of filter plates fixed on the rotating shaft and arranged axially along the shaft. Each set of filter plates includes multiple filter plates evenly arranged around the rotating shaft, with the same spacing between adjacent filter plate sets. The filter plates of adjacent filter plate sets have air vents evenly distributed on opposite sides to form an adsorption side. The filter plates have a first air channel communicating with the adsorption side inside, and a second air channel is provided inside the rotating shaft. The first air channel communicates with the adsorption side. The second air duct is connected to the inlet of the vacuum filter via a pipeline. The turntable is arranged in sequence along the rotation direction of the rotating shaft, including a material adsorption zone, a first atomizing washing zone, a second atomizing washing zone, a compression dehydration zone, and a discharge zone. The material adsorption zone is located on the bottom side of the turntable, and the compression dehydration zone is located on the top side of the turntable. The turntable is installed directly above the material tank, so that the material adsorption zone is placed inside the material tank. The turntable is equipped with atomizing spray devices in both the first and second atomizing washing zones. The turntable is equipped with an auxiliary dehydration device in the compression dehydration zone and a discharge device in the discharge zone.

[0020] In the above embodiments, the filter plate is fan-shaped, and multiple filter plates in the same filter plate group are arranged to form a ring perpendicular to the axis of rotation.

[0021] In the above embodiments, the atomizing spray device includes a first spray device and a second spray device. The first spray device is disposed in the first atomizing washing zone, and the second spray device is disposed in the second atomizing washing zone. The first spray device and the second spray device have the same structure and both include multiple sets of atomizing nozzle groups. The number and position of the atomizing nozzle groups match the number and position of the filter plate groups. Each atomizing nozzle group includes two atomizing nozzles disposed on both sides of the filter plate and facing the two adsorption sides of the filter plate respectively. The liquid inlet of the atomizing nozzle is connected to the main pipeline, and the main pipeline is connected to the liquid storage container through a pump.

[0022] In the above embodiments, the unloading device includes multiple sets of scraper sets. The number and position of the scraper sets match the number and position of the filter plate sets. Each set of scraper sets includes scrapers respectively arranged on both adsorption sides of the filter plate. One end of the scraper is a fixed end, and the other end is a cutting edge. The fixed end of the scraper is slidably mounted on a slide rail. The slide rail is fixed on the frame and parallel to the axis of the rotating shaft. The relative position of the scraper and the slide rail is locked by a locking device. The distance between the cutting edge of the scraper and the adsorption side of the filter plate is less than the minimum particle diameter of the material.

[0023] In the above embodiment, the auxiliary dewatering device includes a pressure plate group and a hydraulic cylinder. The number and position of the pressure plate group match the number and position of the filter plate group. Each pressure plate group includes pressure plates respectively arranged on the two adsorption sides of the filter plate. Two hydraulic cylinders are fixed on the frame. One hydraulic cylinder controls all the pressure plates in the entire pressure plate group located on one side of the filter plate, and the other hydraulic cylinder controls all the pressure plates in the entire pressure plate group located on the other side of the filter plate, so that the two pressure plates on both sides of the filter plate are driven by the two hydraulic cylinders to move closer to each other or further away from each other.

[0024] This invention also includes a graphite purification apparatus comprising a disc filter washing device, comprising a primary batching tank, a primary reaction tank, a primary disc filter washing device, a pulping and batching unit, a secondary reaction tank, a secondary disc filter washing device, a drying device, and a screening and demagnetizing packaging paper device; the primary and secondary disc filter washing devices have the same structure and both employ the aforementioned disc filter washing device; the outlet of the primary batching tank is connected to the inlet of the primary reaction tank via a first pipeline, and a first pump is installed on the first pipeline; the outlet of the primary reaction tank is connected to the feed inlet of the primary disc filter washing device via a second pipeline. The device is connected to a second pump installed on the second pipeline. The outlet of the discharge area of ​​the primary disc filter washing device is connected to the inlet of the pulping and batching unit. The outlet of the pulping and batching unit is connected to the inlet of the secondary reaction tank via a third pipeline, on which a third pump is installed. The outlet of the secondary reaction tank is connected to the inlet of the material pool of the secondary disc filter washing device via a fourth pipeline, on which a fourth pump is installed. The outlet of the discharge area of ​​the secondary disc filter washing device is connected to the inlet of the drying device via a first conveying mechanism. The outlet of the drying device is connected to the screening and demagnetizing packaging paper equipment via a second conveying mechanism.

[0025] In the above embodiments, the gas outlets of the primary batching tank, primary reaction tank, slurry batching unit, and secondary reaction tank are respectively connected to the feed inlet of the acid mist absorption tower through pipelines.

[0026] The present invention also includes a graphite purification method using the above-described graphite purification apparatus, comprising the following specific steps:

[0027] S1. Primary batching: Add graphite raw materials, acid, and water to the primary batching tank according to the set proportions, and stir thoroughly using a stirring device;

[0028] S2, Primary reaction: The mixture after stirring in the primary batching tank is transported to the primary reaction tank by the first pump. Stirring continues in the primary reaction tank. Steam is used to heat the mixture in the primary reaction tank. The temperature of the mixture is controlled between 80 and 90°C. The reaction time is 9 to 16 hours, and then the temperature is maintained for 8 hours.

[0029] S3, Primary Filtration and Washing: The mixture is transported from the primary reaction tank to the material pool of the primary disc filter washing device using the second pump, and the material is washed using the primary disc filter washing device.

[0030] S4, Secondary batching: The material from the discharge area of ​​the primary disc filter washing device enters the pulping and batching unit, where acid and water are added in a set ratio and stirred thoroughly.

[0031] S5. Secondary reaction: The mixture in the pulping and batching unit is transported to the secondary reaction tank by the third pump. The mixture is stirred again in the secondary reaction tank. Then, the mixture in the secondary reaction tank is heated by steam. The temperature is controlled between 65 and 80°C. The reaction time is 3 to 8 hours, and the temperature is maintained for 2 hours.

[0032] S6. Secondary washing: After the secondary reaction is completed, the material is transported to the material tank of the secondary disc filter washing device by the fourth pump, and the material is washed by the secondary disc filter washing device.

[0033] S7. The material in the unloading area of ​​the secondary disc filter washing device is conveyed by the conveying mechanism into the flash evaporation process for drying and dehydration, and then screened, demagnetized, and finally packaged.

[0034] In the above embodiment, in step S2, the specific stirring method of the primary reaction vessel is as follows: the stirring speed is set to 25 r / min to 40 r / min to allow the material to fully contact the acid for reaction. After stirring for 6 hours, the stirring speed is adjusted to 50 r / min to 70 r / min.

[0035] In the above embodiment, in step S5, the stirring speed in the secondary reaction vessel is 50 r / min to 70 r / min.

[0036] With the above structure, the present invention has the following advantages:

[0037] 1. This invention uses a disc filter washing device, which can shorten the reaction time and improve production efficiency. Specifically, the material is adsorbed onto the filter plate by negative pressure, and the material thickness is between 0.5-1cm, which ensures more thorough washing and improves the washing effect.

[0038] By using atomizing nozzles installed outside the filter plate, low-concentration acid and / or pure water can be sprayed onto the material layer adsorbed on the filter plate. This achieves the same effect as the existing technology of stirring and slurrying in the tank. Importantly, it eliminates the need for stirring and a rotating disc, resulting in faster washing speed and higher efficiency.

[0039] Extrusion dewatering device: After the material outside the filter plate is washed twice, the moisture content is high. The material is dewatered by extrusion through the pressure plate to reduce the moisture content to below 20%. The pressure plate is made of PPH material to avoid contaminating the material.

[0040] Unloading device: After the material has squeezed out the water, the turntable rotates to the unloading device area. The scrapers on both sides of the turntable peel off the material from the filter plate. The scrapers themselves are fixed on the frame. The relative movement between the filter plate and the scrapers is achieved by the rotation of the turntable, thereby peeling off the material and letting it fall in. No additional power is required, which makes the structure simple and the cost low.

[0041] 2. Replacing filter presses and centrifuges with disc filter washing devices offers the following advantages: ① A single unit can achieve a daily production capacity of 30-60 tons, more than double the efficiency of traditional filter presses. ② High degree of automation; two units can be operated by just one person. ③ Excellent washing effect; the equipment uses high-pressure atomizing nozzles for rinsing, resulting in better washing of materials and thorough removal of impurity ions, thereby reducing washing time and material reaction time.

[0042] 3. Spraying can enhance the rinsing effect. On the one hand, it reduces the amount of acid used, thereby reducing the cost of wastewater treatment and improving the company's efficiency. On the other hand, rinsing is more thorough in washing materials and can fully remove impurity ions, thereby reducing washing time, saving water resources, and reducing wastewater treatment costs and material reaction time.

[0043] 4. The filter plate is made of ceramic, which has a higher mesh count and is more durable than ordinary filter cloth. This can reduce the loss of materials during washing and thus improve the material recovery rate.

[0044] 5. Reducing the number of filter presses and centrifuges significantly reduces equipment investment and maintenance costs, thereby reducing maintenance personnel, lowering labor costs, and improving company efficiency.

[0045] In summary, this invention enables the graphite purification unit to achieve a daily production capacity of 30-50 tons, more than double the efficiency of traditional filter presses, thus increasing production capacity. Furthermore, the use of a disc filter washing device eliminates the need for manual material shoveling; two machines can be operated by just one person. Based on an annual production of 20,000 tons, the number of people on a single production line can be reduced from 16 to 8, significantly lowering labor costs. For an annual production of 20,000 tons, existing designs using filter presses and centrifuges for washing require 5 filter presses and 10 centrifuges to meet the demand, resulting in high equipment costs, procurement costs, and maintenance costs. In contrast, this invention only requires 5 machines, resulting in lower investment and maintenance costs. Attached Figure Description

[0046] Figure 1 A flowchart of the existing graphite purification process.

[0047] Figure 2 This is a flowchart of the graphite purification process of the present invention.

[0048] Figure 3 This is a schematic diagram of the structure of the disc filter washing device of the present invention.

[0049] Figure 4 This is a schematic diagram of the structure of the turntable of the present invention.

[0050] Figure 5 This is a schematic diagram of the filter plate of the present invention.

[0051] Figure 6 This is a schematic diagram of the structure of the atomizing nozzle of the present invention.

[0052] In the attached diagram: 1. Primary batching tank; 2. Primary reaction tank; 3. Primary disc filter washing device; 4. Pulping and batching unit; 5. Secondary reaction tank; 6. Secondary disc filter washing device; 7. Drying device; 8. Screening and demagnetizing packaging paper equipment; 31. Turntable; 311. Rotating shaft; 312. Filter plate; 313. Material adsorption zone; 314. First atomizing washing zone; 315. Second atomizing washing zone; 316. Extrusion and dewatering zone; 317. Discharge zone; 32. Auxiliary dewatering device; 321. Pressure plate; 322. Hydraulic cylinder; 33. Discharge device; 331. Scraper; 332. Slide rail; 34. Material pool; 35. Atomizing spray device; 351. First spray device; 352. Second spray device; 353. Atomizing nozzle. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0054] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0055] like Figure 3As shown, a disc filtration and washing device includes a material tank 34, a turntable 31, an auxiliary dewatering device 32, and a discharge device 33. The turntable 31 includes a frame, a rotating shaft 311 rotatably mounted on the frame, a motor driving the rotating shaft 311 to rotate, and multiple sets of filter plates fixed on the rotating shaft 311 and arranged axially along the rotating shaft 311. Each set of filter plates includes multiple filter plates 312 evenly arranged around the rotating shaft 311. The spacing between adjacent filter plate sets is the same. The filter plates 312 of adjacent filter plate sets are evenly covered with air vents on opposite sides to form an adsorption side. In this embodiment, the filter plates are made of ceramic filter plates. The spacing between adjacent filter plates 312 within the same set of filter plates is the same. The filter plates 312 have a first air passage communicating with the adsorption side inside, and the rotating shaft 311 has a second air passage inside. The first air passage communicates with the second air passage, and the second air passage is connected to the inlet of a vacuum filter through a pipeline.

[0056] like Figure 5 As shown, the turntable 31 is provided with a material adsorption zone 313, a first atomizing washing zone 314, a second atomizing washing zone 315, a compression dehydration zone 316, and a discharge zone 317 in sequence along the rotation direction of the rotating shaft 311. Specifically, the material adsorption zone 313 is located on the bottom side of the turntable 31, the compression dehydration zone 316 is located on the top side of the turntable 31, and the turntable 31 is installed directly above the material pool 34, so that the material adsorption zone 313 is placed inside the material pool 34. The turntable 31 is provided with atomizing spray devices in both the first atomizing washing zone 314 and the second atomizing washing zone 315. The turntable 31 is equipped with an auxiliary dehydration device 32 in the compression dehydration zone 316, and the turntable 31 is equipped with a discharge device in the discharge zone 317.

[0057] In this embodiment, the filter plate 312 is fan-shaped, and multiple filter plates in the same filter plate group form a ring perpendicular to the rotating shaft 311.

[0058] like Figure 6 As shown, the atomizing spray device includes a first spray device 351 and a second spray device 352. The first spray device 351 is located in the first atomizing washing zone 314 and is used to spray dilute hydrochloric acid. The second spray device 352 is located in the second atomizing washing zone 315 and is used to spray pure water. The first spray device 351 and the second spray device 352 have the same structure and both include multiple sets of atomizing nozzle groups. The number and position of the atomizing nozzle groups match the number and position of the filter plate groups. Each set of atomizing nozzle groups includes two atomizing nozzles 353 located on both sides of the filter plate 312 and facing the two adsorption sides of the filter plate 312 respectively. The liquid inlet of the atomizing nozzle 353 is connected to the main pipeline, and the main pipeline is connected to the liquid storage container through a pump.

[0059] The unloading device includes multiple sets of scraper groups, the number and position of which match the number and position of the filter plate groups. Each set of scraper groups includes scrapers 331 respectively disposed on the two adsorption sides of the filter plate 312. In this embodiment, the scrapers are made of titanium alloy. One end of each scraper 331 is a fixed end, and the other end is a cutting edge. The fixed end of the scraper 331 is slidably mounted on a slide rail 332, which is fixed to the frame and locked in relative position with a locking device. The slide rail 332 is axially parallel to the rotating shaft 311. The distance between the scraper 331 and the filter plate 312 can be adjusted via the slide rail 332 to avoid damaging the filter plate surface. The locking device can be a pin hole and pin shaft fit, or a stepless adjustable locking device as used in the prior art. The distance between the cutting edge of the scraper 331 and the adsorption side of the filter plate 312 is less than the minimum particle diameter of the material, thus ensuring that the material can be scraped off the filter plate surface.

[0060] like Figure 4 As shown, the auxiliary dewatering device 32 includes a pressure plate assembly and hydraulic cylinders 322. The number and position of the pressure plate assemblies match the number and position of the filter plate assemblies. Each pressure plate assembly includes pressure plates 321 respectively disposed on the two adsorption sides of the filter plate 312. Two hydraulic cylinders 322 are fixed on the frame. One hydraulic cylinder controls the pressure plate on one side of the filter plate in the entire pressure plate assembly, and the other hydraulic cylinder controls the pressure plate on the other side of the filter plate in the entire pressure plate assembly. Specifically, it also includes two connecting rods. The connecting rods are arranged parallel to the rotating shaft 311, and the two ends of the connecting rods are slidably mounted on the frame. The connecting rods move axially through the drive of the hydraulic cylinders, and are positioned on the filter plate. All the pressure plates on one side of the filter plate are mounted on a connecting rod, and all the pressure plates on the other side of the filter plate are mounted on another connecting rod. This enables the linkage of all filter plates to be controlled by two hydraulic cylinders. The two pressure plates 321 on both sides of the filter plate 312 are driven by two hydraulic cylinders 322 to move closer or further apart, thereby squeezing and dewatering the material on the filter plate 312. When the hydraulic cylinders 322 work, they drive the pressure plates 321 on both sides of the filter plate 312 to squeeze, achieving the effect of auxiliary dewatering. The pressure plates 321 are made of PPH material, and the side that contacts the material is made of soft plastic to avoid contamination of the material.

[0061] This device utilizes the rotation of turntable 31 to sequentially perform adsorption, acid washing, water washing, dehydration, and unloading of materials. Specifically, through the cooperation of a vacuum filter and filter plate 312, when filter plate 312 enters the material tank 34, the vacuum adsorbs the material onto the surface of filter plate 312, achieving adsorption of solid materials by filter plate 312. By controlling the suction force, the thickness of the material adsorbed on filter plate 312 is ensured to meet the requirements of subsequent rapid acid washing and water washing (in this embodiment, a material adsorption thickness of 0.5-1cm on filter plate 312 is more effective). Then, filter plate 312 enters the first atomizing washing zone 314 and the second atomizing washing zone 315. Through close-range spraying of the material by atomizing nozzles, the amount of acid used can be reduced, thereby reducing the wastewater treatment efficiency. This design reduces costs and effectively removes impurity ions, thereby reducing washing and material reaction time and ensuring the efficiency of acid washing and water washing. The material then enters the extrusion dewatering zone 316, where the turntable 31 is stopped to allow the pressure plate 321 to extrude and dewater the material on the filter plate 312. The stop of the turntable 31, in conjunction with the position of the preceding spray, enhances the spraying effect. After dewatering, the material enters the unloading zone, separating it from the filter plate 312 for subsequent processes. This structure improves the filtration and washing efficiency of graphite during purification. A single unit can achieve a daily capacity of 30-60 tons, more than double the efficiency of traditional filter presses. Furthermore, the equipment is highly automated; two units can be operated by a single person.

[0062] like Figure 2 As shown, the present invention also includes a graphite purification apparatus, comprising a primary batching tank 1, a primary reaction tank 2, a primary disc filter washing device 3, a pulping and batching unit 4, a secondary reaction tank 5, a secondary disc filter washing device 6, a drying device 7, and a screening and demagnetizing packaging paper device 8; the primary disc filter washing device 3 and the secondary disc filter washing device 5 have the same structure and both employ the aforementioned... Figure 3The disc filter washing device shown has the following configuration: the outlet of the primary batching tank 1 is connected to the inlet of the primary reaction tank 2 via a first pipeline, on which a first pump is installed; the outlet of the primary reaction tank 2 is connected to the inlet of the material pool of the primary disc filter washing device 3 via a second pipeline, on which a second pump is installed; the outlet of the discharge area 317 of the primary disc filter washing device 3 is connected to the inlet of the pulping and batching unit 4; the outlet of the pulping and batching unit 4 is connected to the inlet of the secondary reaction tank 5 via a third pipeline, on which a third pump is installed; and the outlet of the secondary reaction tank 5 is connected to the inlet of the material pool of the secondary disc filter washing device 6 via a fourth pipeline, on which a fourth pump is installed. The outlet of the discharge zone 317 of the secondary disc filter washing device 6 is connected to the inlet of the drying device 7 through a first conveying mechanism. The outlet of the drying device 7 is connected to the screening and demagnetizing packaging paper equipment 8 through a second conveying mechanism. The drying device 7 adopts a flash drying device. The screening and demagnetizing packaging paper equipment 8 includes a vibrating screen, a demagnetizer, and a packaging machine connected in sequence according to the process. The flash drying device, vibrating screen, demagnetizer, and packaging machine are all existing equipment, and their structures are not described in detail here. In this embodiment, the first pump, the second pump, the third pump, and the fourth pump are all centrifugal pumps. The gas outlets of the primary batching tank 1, the primary reaction tank 2, the pulping and batching unit 4, and the secondary reaction tank 5 are respectively connected to the feed of the acid mist absorption tower 9 through pipelines.

[0063] The specific process flow of the graphite purification method of the present invention is as follows:

[0064] Pre-production preparation: Inspect the incoming graphite material and set the ratio of graphite raw materials, acid, and water according to the quality of the graphite.

[0065] In this embodiment, the acid ratio includes, but is not limited to, the following combinations:

[0066] Combination A: (hydrochloric acid, hypochlorous acid, hydrofluoric acid); Combination B: (hydrochloric acid, sulfuric acid, hydrofluoric acid); Combination C: (sulfuric acid, nitric acid, hydrofluoric acid); Combination D: (hydrochloric acid, nitric acid, hydrofluoric acid); Combination E: (hydrochloric acid, formic acid, hydrofluoric acid); Combination F: (sulfuric acid, formic acid, hydrofluoric acid); Combination G: (hydrochloric acid, hydrofluoric acid); Combination H: (sulfuric acid, hydrofluoric acid); Combination I: (hydrochloric acid, nitric acid); Combination J: (hydrochloric acid, hydrofluoric acid).

[0067] S1. Primary batching: According to the settings, graphite raw materials, acid, and water are added to the primary batching tank and thoroughly stirred by the stirring device.

[0068] S2, Primary Reaction: The mixture stirred in the primary batching tank is transported to the primary reaction tank by the first pump. The mixture is stirred again in the primary reaction tank. First, the stirring speed is controlled at 25 r / min to 40 r / min to allow the material to fully contact the acid and react. After stirring for 6 hours, the stirring speed is adjusted to 50 r / min to 70 r / min to allow the impurities to be better separated from the graphite. Then, the mixture in the primary reaction tank is heated with steam. The temperature of the mixture is controlled between 80 and 90°C. The reaction time is 9 to 16 hours, and then the temperature is maintained for 8 hours.

[0069] S3, Primary Filtration and Washing: The mixture is transported from the primary reaction tank to the material pool of the primary disc filter washing device using the second pump, and the material is washed using the primary disc filter washing device.

[0070] Specifically: The rotation of the turntable drives the rotation of the filter plate, and the negative pressure of the filter plate adsorbs the material in the pool onto the filter plate, thereby achieving rapid solid-liquid separation.

[0071] When the turntable drives the filter plate away from the material adsorption zone and rotates to the first atomizing washing zone, the material on the filter plate is sprayed with dilute hydrochloric acid through the atomizing nozzle in the first atomizing washing zone for rinsing (in this embodiment, dilute hydrochloric acid generally refers to dilute hydrochloric acid with a concentration of 2%). Since the hydrogen ions in the dilute hydrochloric acid can react with the impurity ions in the material, the impurity ions attached to the surface of the material can be transferred to the solution. Then, the solution can be quickly separated from the material by negative pressure, achieving a more ideal washing effect.

[0072] When the turntable moves the filter plate away from the first atomizing washing zone and into the second atomizing washing zone, pure water is sprayed onto the material on the filter plate through the atomizing nozzles in the second atomizing washing zone to rinse it, consolidate the washing effect, and wash the pH value of the material to neutral.

[0073] When the turntable moves the filter plate away from the second atomizing washing zone and into the extrusion dewatering zone, the pressure plates on both sides of the filter plate extrude pressure on the material to assist in dewatering. The auxiliary dewatering device includes a hydraulic cylinder and pressure plates. When the hydraulic cylinder operates, it drives the pressure plates on both sides of the filter plate to extrude pressure on the filter plate, achieving the effect of auxiliary dewatering. The pressure plates are made of PPH material, and the side in contact with the material is made of soft plastic to avoid contamination of the material. In the extrusion dewatering zone, the turntable stops rotating, and resumes rotation after extrusion is completed.

[0074] When the turntable drives the filter plate to the unloading area, the unloading device peels the material off the filter plate. The unloading device uses a scraper made of titanium alloy fixed on both sides of the filter plate. The scraper is mounted on a slide rail, which is parallel to the axis of the turntable. The distance between the scraper and the filter plate can be adjusted by the slide rail to avoid damaging the surface of the filter plate.

[0075] When using the aforementioned disc filter washing device to wash materials, the materials are adsorbed onto the filter plate surface under negative pressure. The thickness of the material adsorbed on the filter plate can be adjusted by changing the pressure. During the washing process, the material adheres better to the filter plate due to the washing water, and after compression, the material becomes more compact, ensuring that it does not fall off when entering the unloading area. This washing process is continuous and intermittent, with short processing time and high efficiency. High-pressure atomizing nozzles are used for rinsing, resulting in less water consumption and better washing effect. The specially designed filter plates minimize material loss and maximize yield. This equipment has a high degree of automation, reducing labor input and further improving efficiency.

[0076] S4, Secondary batching: The material from the discharge area of ​​the primary disc filter washing device enters the pulping and batching unit, where acid and water are added in a set ratio and thoroughly stirred.

[0077] S5. Secondary reaction: The mixture in the pulping and batching unit is transported to the secondary reaction tank by the third pump. The mixture is stirred again in the secondary reaction tank at a speed of 50 r / min to 70 r / min. Then, the mixture in the secondary reaction tank is heated by steam at a temperature of 65 to 80°C for 3 to 8 hours, followed by a 2-hour heat preservation period.

[0078] S6. Secondary washing: After the secondary reaction is completed, the material is transported to the material tank of the secondary disc filter washing device by the fourth pump. The material is washed again by the secondary disc filter washing device. The structure of the secondary disc filter washing device is the same as that of the primary disc filter washing device. The specific washing process will not be described in detail.

[0079] S7. After the material in the unloading area of ​​the secondary disc filter washing device is bagged, it enters the flash evaporation process for drying and dehydration, then is screened, demagnetized, and finally packaged.

[0080] The following is a specific embodiment of graphite purification according to the above-described graphite purification method:

[0081] Example 1:

[0082] Based on the quality of the incoming materials, select acid combination B. Hydrochloric acid, sulfuric acid, hydrofluoric acid, and water are added to the primary mixing tank in a ratio of 3:1:1:5 and rapidly mixed with the graphite raw materials. After mixing, the materials are transferred to the primary reaction tank, where stirring continues at a speed of 25 r / min to 40 r / min. After stirring for 6 hours, the speed is adjusted to 50 r / min to 70 r / min. Then, the mixture is heated to 80 to 90°C using steam and kept at that temperature for 8 hours. The reaction takes place in the primary reaction tank for 14 hours.

[0083] After the first reaction is completed, the material is conveyed to a primary disc filter washing device for solid-liquid separation and washing. After washing, the acid of combination I is selected in the batching and pulping area of ​​the primary disc filter washing device. Hydrochloric acid, nitric acid and water are added to the batching and pulping unit in a ratio of 3:1:6 and stirred again with the material. After stirring, it is conveyed to the secondary reaction tank.

[0084] In a secondary reaction vessel, the material is heated to 65–80°C using steam and held at this temperature for 2 hours. The stirring speed is controlled at 50–70 r / min, and the reaction continues for 6 hours. After the reaction, a centrifugal pump transfers the material to a secondary disc filter washing device for solid-liquid separation and washing. Depending on quality requirements, the material can undergo three disc filter washing processes. After washing, the material is packaged in ton bags for sampling and testing. The qualified material is then flash-dried to a moisture content of 0.1%, followed by sieving, demagnetization, and finally, fixed-weight packaging.

[0085] Example 2:

[0086] Based on the quality of the incoming materials, acid combination B was selected. Hydrochloric acid, sulfuric acid, hydrofluoric acid, and water were added to the primary mixing tank in a ratio of 2.5:1:1:4.5 and rapidly mixed with the graphite raw materials. The material was then transferred to the primary reaction tank. The stirring speed was controlled at 25-40 rpm, and after 6 hours of stirring, it was adjusted to 50-70 rpm. The mixture was then heated to 80-90°C using steam and held at that temperature for 8 hours, allowing the reaction to proceed for 12 hours within the tank.

[0087] After the first reaction is completed, the material is conveyed to a primary disc filter washing machine for solid-liquid separation and washing. After washing, the acid of combination I is selected in the batching and pulping area of ​​the primary disc filter washing device. Hydrochloric acid, nitric acid and water are added to the batching and pulping unit in a ratio of 2:1:7 and stirred with the material again. After stirring, it is conveyed to the secondary reaction tank.

[0088] In a secondary reaction vessel, the material is heated to 65–80°C using steam and held at this temperature for 2 hours. The stirring speed is controlled at 50–70 r / min, and the reaction continues for 4 hours. After the reaction, a centrifugal pump transfers the material to a secondary disc filter washing device for solid-liquid separation and washing. Depending on quality requirements, the material can undergo three disc filter washing processes. After washing, the material is packaged in ton bags for sampling and testing. The qualified material is flash-dried to a moisture content of 0.1%, then sieved and demagnetized, and finally packaged by weight.

[0089] Comparative Example 1:

[0090] Comparative Example 1 adopts the existing process flow mentioned in the background art, such as Figure 1As shown, acid combination B was selected, with hydrochloric acid, sulfuric acid, hydrofluoric acid, and water added to the primary mixing tank in a ratio of 3:1:1:5. This mixture was then rapidly mixed with the graphite raw material and stirred. A diaphragm pump was used to transfer the material to the primary reaction tank. The stirring speed was controlled at 25-40 rpm, and after 6 hours of stirring, it was adjusted to 50-70 rpm. The mixture was heated to 80-90°C using steam and held at that temperature for 8 hours, allowing the reaction to proceed for 18 hours within the tank.

[0091] After the first reaction is completed, the material is conveyed to a primary filter press for solid-liquid separation and washing. After washing, the material is manually shoveled off the filter plate and fed into a secondary mixing tank. Select acid combination I, in which hydrochloric acid, nitric acid, and water are added to the secondary mixing tank in a ratio of 3:1:6 and stirred again with the material. After stirring, the mixture is pumped to the secondary reaction tank using a centrifugal pump.

[0092] In a secondary reaction tank, the material is heated to 65–80°C using steam and held at this temperature for 2 hours. The stirring speed is controlled at 50–70 r / min, and the reaction continues for 12 hours. After the reaction, the material is pumped to a secondary filter press for solid-liquid separation and washing. The pH value is washed to neutral. The material is then transferred from the filter plate to a tertiary mixing tank, where water is added at a ratio of 1:1.2 and stirred. After stirring, the material is transferred to a centrifuge for washing. After centrifugation and washing, the material is collected in ton bags. Samples of the material are taken for testing. The qualified material is flash-dried to a moisture content of 0.1%, then sieved for demagnetization, and finally packaged by weight.

[0093] Comparative Example 2:

[0094] Comparative Example 2 also adopts the existing process flow mentioned in the background art, such as Figure 1 As shown, acid combination D was selected, with hydrochloric acid, nitric acid, hydrofluoric acid, and water added to a primary mixing tank in a ratio of 3:2:1:4 for rapid mixing and stirring. A diaphragm pump was then used to transfer the materials to a primary reaction tank. The stirring speed was controlled at 25-40 rpm, and after 6 hours of stirring, it was adjusted to 50-70 rpm. The mixture was heated to 80-90°C using steam and held at that temperature for 8 hours, allowing the reaction to proceed for 17 hours within the tank.

[0095] After the first reaction, the material is conveyed to a primary filter press for solid-liquid separation and washing. After washing, the material is manually shoveled off the filter plate and fed into a secondary mixing tank. Select acid from group I, in which hydrochloric acid, nitric acid, and water are added to the secondary mixing tank in a ratio of 3:2:5 and stirred again with the material. After stirring, the mixture is pumped to the secondary reaction tank using a centrifugal pump.

[0096] In a secondary reaction tank, the material is heated to 65–80°C using steam and held at this temperature for 2 hours. The stirring speed is controlled at 50–70 r / min, and the reaction continues for 11 hours. After the reaction, the material is pumped to a secondary filter press for solid-liquid separation and washing. The pH is washed until neutral. The material is then transferred from the filter plate to a tertiary mixing tank, where water is added at a ratio of 1:1.2 and stirred. After stirring, the mixture is transferred to a centrifuge for washing. After centrifugation and washing, the material is collected in ton bags. Samples are taken for testing. The qualified material is flash-dried to a moisture content of 0.1%, then sieved for demagnetization, and finally packaged by weight.

[0097] The comparison and analysis of the data from the examples and comparative examples are shown in the table below:

[0098]

[0099] The data in the table above shows that the trace element results of materials washed using the disc filter of this invention are superior to those washed using filter presses and centrifuges. The customized disc filter washer offers advantages in terms of capacity, washing process, maintenance, and cost compared to traditional filter presses and centrifuges.

[0100] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made under the concept of the present invention using the description and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A disc filter washing device, characterized in that: The device includes a material tank, a turntable, an auxiliary dewatering device, and a discharge device. The turntable includes a frame, a rotating shaft mounted on the frame, a motor driving the shaft, and multiple sets of filter plates fixed on the shaft and arranged axially along the shaft. Each set of filter plates includes multiple filter plates evenly distributed around the shaft, with equal spacing between adjacent sets. The filter plates in adjacent sets have air vents on opposite sides to form an adsorption side, and the filter plates are under negative pressure. The turntable has a material adsorption zone, a first atomizing washing zone, a second atomizing washing zone, a compression dewatering zone, and a discharge zone arranged sequentially along the rotation direction of the shaft. The material adsorption zone is located on the bottom side of the turntable, and the compression dewatering zone is located on the top side. The turntable is installed directly above the material tank, so that the material adsorption zone is placed inside the material tank. The turntable has atomizing spray devices in both the first and second atomizing washing zones, an auxiliary dewatering device in the compression dewatering zone, and a discharge device in the discharge zone. The atomizing spray device includes a first spray device and a second spray device. The first spray device is used to spray dilute hydrochloric acid (2% concentration). The second spray device is used to spray pure water. The first spray device is located in the first atomizing washing zone, and the second spray device is located in the second atomizing washing zone. The first and second spray devices have the same structure and both include multiple sets of atomizing nozzles. The number and position of the atomizing nozzles match the number and position of the filter plate sets. Each set of atomizing nozzles includes two atomizing nozzles located on both sides of the filter plate and facing the two adsorption sides of the filter plate respectively. The material adsorption thickness on the filter plate is between 0.5-1cm. The atomizing nozzles spray the material at close range, reducing the amount of acid used. The unloading device includes multiple sets of scraper sets. The number and position of the scraper sets match the number and position of the filter plate sets. Each set of scraper sets includes scrapers respectively arranged on the two adsorption sides of the filter plate. One end of the scraper is a fixed end and the other end is a cutting edge. The fixed end of the scraper is slidably mounted on a slide rail. The slide rail is fixed on the frame and parallel to the axis of the rotating shaft. The relative position of the scraper and the slide rail is locked by a locking device. The distance between the cutting edge of the scraper and the adsorption side of the filter plate is less than the minimum particle diameter of the material. The auxiliary dewatering device includes a pressure plate assembly and hydraulic cylinders. The number and position of the pressure plate assemblies match the number and position of the filter plate assemblies. Each pressure plate assembly includes pressure plates respectively set on the two adsorption sides of the filter plate. Two hydraulic cylinders are fixed on the frame. One hydraulic cylinder controls the pressure plate on one side of the filter plate in the entire pressure plate assembly, and the other hydraulic cylinder controls the pressure plate on the other side of the filter plate in the entire pressure plate assembly, so that the two pressure plates on both sides of the filter plate are driven by the two hydraulic cylinders to move closer or further apart from each other.

2. The disc filter washing device according to claim 1, characterized in that: The filter plates are fan-shaped, and multiple filter plates in the same filter plate group form a ring perpendicular to the axis of rotation.

3. The disc filter washing device according to claim 1, characterized in that: The liquid inlet of the atomizing nozzle is connected to the main pipeline, which is connected to the liquid storage container via a pump.

4. A graphite purification apparatus, comprising a primary batching tank, a primary reaction tank, a primary disc filter washing device, a pulping and batching unit, a secondary reaction tank, a secondary disc filter washing device, a drying device, and a screening and demagnetizing packaging paper device; wherein the primary disc filter washing device and the secondary disc filter washing device have the same structure and both employ the disc filter washing device as described in any one of claims 1 to 3, characterized in that: The discharge port of the primary batching tank is connected to the inlet of the primary reaction tank via a first pipeline, on which a first pump is installed. The discharge port of the primary reaction tank is connected to the inlet of the material pool of the primary disc filter washing device via a second pipeline, on which a second pump is installed. The outlet of the discharge area of ​​the primary disc filter washing device is connected to the inlet of the pulping and batching unit. The discharge port of the pulping and batching unit is connected to the inlet of the secondary reaction tank via a third pipeline, on which a third pump is installed. The discharge port of the secondary reaction tank is connected to the inlet of the material pool of the secondary disc filter washing device via a fourth pipeline, on which a fourth pump is installed. The outlet of the discharge area of ​​the secondary disc filter washing device is connected to the inlet of the drying device via a first conveying mechanism. The discharge port of the drying device is connected to the screening and demagnetizing packaging paper equipment via a second conveying mechanism.

5. The graphite purification apparatus according to claim 4, characterized in that: The gas outlets of the primary batching tank, the primary reaction tank, the pulping and batching unit, and the secondary reaction tank are all connected to the inlet of the acid mist absorption tower via pipelines.

6. A method for purifying graphite using the graphite purification apparatus according to claim 4 or 5, characterized in that: The specific steps include the following: S1. Primary batching: Add graphite raw materials, acid, and water to the primary batching tank according to the set proportions, and stir thoroughly using a stirring device; S2, Primary reaction: The mixture after stirring in the primary batching tank is transported to the primary reaction tank by the first pump. The mixture is stirred again in the primary reaction tank. Then, the mixture is heated by steam. The temperature of the mixture is controlled between 80 and 90°C. The reaction time is 9 to 16 hours. Then, the mixture is kept at the temperature for 8 hours. S3, Primary Filtration and Washing: The mixture is transported from the primary reaction tank to the material pool of the primary disc filter washing device using the second pump, and the material is washed using the primary disc filter washing device. S4, Secondary batching: The material from the unloading area of ​​the primary disc filter washing device enters the pulping and batching unit, where acid and water are added in a set ratio and stirred thoroughly. S5. Secondary reaction: The mixture in the pulping and batching unit is transported to the secondary reaction tank by the third pump. The mixture is stirred again in the secondary reaction tank. Then, the mixture in the secondary reaction tank is heated by steam. The temperature is controlled between 65 and 80°C. The reaction time is 3 to 8 hours, and the temperature is maintained for 2 hours. S6. Secondary washing: After the secondary reaction is completed, the material is transported to the material tank of the secondary disc filter washing device by the fourth pump, and the material is washed by the secondary disc filter washing device. S7. The material in the unloading area of ​​the secondary disc filter washing device is conveyed by the conveying mechanism into the flash evaporation process for drying and dehydration, and then screened, demagnetized, and finally packaged.

7. The graphite purification method according to claim 6, characterized in that: In step S2, the specific stirring method of the reaction vessel is as follows: first, the stirring speed is set to 25 r / min to 40 r / min to allow the material to fully contact the acid for reaction. After stirring for 6 hours, the stirring speed is adjusted to 50 r / min to 70 r / min.

8. The graphite purification method according to claim 6, characterized in that: In step S5, the stirring speed in the secondary reaction vessel is 50 r / min to 70 r / min.

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