Ultra-pure microcrystalline graphite purification system and production process thereof

Abstract

The invention discloses an ultra-pure microcrystalline graphite purification system and a production process thereof, and relates to the technical field of microcrystalline graphite purification processes, the ultra-pure microcrystalline graphite purification system comprises a crusher, a grinder, a flotation machine, an acid tank, a reaction kettle, a centrifuge, a dryer and a sewage treatment box; the crusher is connected with the grinding machine through a conveying belt, the grinding machine is connected with the flotation machine through a conveying pipe, the flotation machine is connected with the reaction kettle through a pipeline with a valve, and the acid tank is connected with the reaction kettle through a pump body to inject acid into an inner cavity of the reaction kettle for purification. According to the invention, the centrifugal machine blow-off pipeline and the drying machine blow-off pipeline are mutually matched with the sewage treatment tank, so that acid water generated after dehydration of the centrifugal machine and excessive acid water generated during drying of the drying machine can enter the sewage treatment tank to be subjected to neutralization reaction with the lime rod, and meanwhile, the acid water is immersed in the water storage tank; and finally, the discharged acid water is purified and can be recycled, so that environmental pollution is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of microcrystalline graphite purification technology, and in particular to an ultrapure microcrystalline graphite purification system and a production process thereof. Background Art

[0002] Graphite is a high-energy crystalline carbon material. Due to its unique structure and electrical conductivity, thermal conductivity, lubrication, high temperature resistance, stable chemical properties, etc., it is widely used in metallurgy, machinery, environmental protection, chemical industry, refractory, new energy, nuclear energy, electronics, medicine, military industry, aerospace and other fields. Natural graphite can be divided into crystalline graphite and microcrystalline graphite according to the degree of crystallization. The purification of microcrystalline graphite is mostly based on the technology of crystalline graphite. Common purification methods include flotation, high temperature method, alkali acid method, hydrofluoric acid method, chlorination roasting method, etc. The existing technology has the following problems:

[0003] Because the existing flotation method is mostly used for the preliminary purification of crystalline graphite, the grade of graphite products is not high and the recovery rate is very low. The alkaline acid method, hydrofluoric acid method and chlorination roasting method are all methods for chemically purifying graphite. Among them, the disadvantage of the alkaline acid method for purifying graphite is that it requires high-temperature calcination, large energy consumption, and a long purification reaction time. This method is more corrosive to equipment, and the purity of graphite obtained by this method cannot reach 99.9%. Although the high-temperature method has the best purification effect, its cost is too high and the capital investment required for industrialization is huge. The hydrofluoric acid method is efficient in purifying graphite and has low energy consumption, but the amount of hydrofluoric acid used is huge and it is highly toxic and corrosive, resulting in high production equipment and environmental protection costs. Summary of the invention

[0004] The present invention provides an ultrapure microcrystalline graphite purification system and a production process thereof to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] An ultrapure microcrystalline graphite purification system and a production process thereof, comprising a crusher, a grinder, a flotation machine, an acid tank, a reactor, a centrifuge, a dryer, and a sewage treatment tank; the crusher and the grinder are connected via a conveyor belt, the grinder and the flotation machine are connected via a conveying pipe, the flotation machine is connected to the reactor via a pipeline with a valve, the acid tank is connected to the reactor via a pump body, and acid is injected into the inner cavity of the reactor for purification, the reactor is connected to the centrifuge via a pipeline, the centrifuge is connected to the dryer via a pipeline, the purified graphite is washed and dried by the centrifuge and the dryer to remove residual acid and alkali impurities, the sewage pipe of the centrifuge is fixedly connected to the input end of the sewage treatment tank, and the sewage treatment tank is used to purify residual acid liquid.

[0007] A process for purifying ultrapure microcrystalline graphite comprises the following steps:

[0008] Step 1: Raw material preparation, select low ash, high purity aggregate as raw material;

[0009] Step 2: Preliminary purification by flotation, using flotation to remove most impurities and obtain graphite concentrate with a high fixed carbon content;

[0010] Step 3: Deep purification by chemical method, select hydrofluoric acid method to further purify graphite;

[0011] Step 4: Dehydration and drying treatment: dehydration and drying of the purified graphite to remove residual acid and alkali impurities;

[0012] Step 5: Sewage treatment, recycling waste liquid through sewage treatment tanks to reduce waste liquid discharge and environmental pollution.

[0013] A further improvement of the technical solution of the present invention is that in step one, the selected aggregate is first crushed by a crusher until the particle size remains at one centimeter in diameter, and then the crushed aggregate particles are evenly conveyed to a grinder by a conveyor belt for grinding, and the grinding is stopped and set aside when the aggregate particles become powder.

[0014] The further improvement of the technical solution of the present invention is that: in the step 2, the powdered aggregate is transported to the flotation machine by pipeline, and the flotation agent is injected into the flotation machine to enrich the target mineral selected in the gas-liquid interface, so as to achieve separation from the impurity minerals and thus achieve the purpose of purification. The flotation agent includes a collector: coal tar, a foaming agent: pine oil, butyl ether oil, and an inhibitor: water glass, sodium fluorosilicate. After preliminary flotation purification, the purity of graphite can reach 80% to 90%.

[0015] A further improvement of the technical solution of the present invention is that in the step three, the preliminarily purified graphite is injected into the reactor, and HF, Hc1, HNO3, and H2SO4 are added to the acid tank in advance, with an overall mass ratio of HF:Hc1:HNO3:H2SO4=2:2:1:1, and the quantity is determined by observing the capacity scale of the acid tank. After preparation, the valve is opened and the mixture flows into the reactor through the pump body. The reactor is charged with 1 ton of material at a time, which is a batch. 600 kg of acid and 300 kg of water are added, and the material can be qualified after two acid washings.

[0016] The technical solution of the present invention is further improved in that: the dehydration treatment in the step 4 is performed by injecting the pickled graphite into a centrifuge for dehydration. The centrifuge mainly has a filter cloth inside. The material carries water under the high-speed rotating centrifugal action, and the water is filtered out through the filter cloth. The filter cloth is 1000-2000 meshes while adding water for washing and filtering. At the same time, a certain thickness of material is applied to the filter cloth, and the material is not removed for cleaning, so as to increase the resistance to material loss, thereby preventing the loss of fine material. The centrifuge is charged with 200 kg of material at a time, and one batch is centrifuged 5 times. 5 tons of water are required to wash one ton of graphite, and the water content of the centrifuged material is controlled within 25%.

[0017] A further improvement of the technical solution of the present invention is that the drying treatment in step 4 adopts two-step microwave drying, that is, the dehydrated graphite is first dried for one hour in a microwave drying oven to remove a certain amount of moisture, and then the drying is repeated once to achieve the drying purpose, and the moisture is controlled below 0.05%.

[0018] A further improvement of the technical solution of the present invention is that: the sewage treatment box in step five is used to collect moisture during centrifuge dehydration and moisture generated during drying treatment. The sewage treatment box is divided into two front and rear chambers, one chamber is an acid water collection chamber, and the other chamber is a neutralization chamber. Several lime sticks are evenly placed in the neutralization chamber and the lime sticks are replaced regularly. The lime sticks can neutralize the acid in the acid water. The neutralized water needs to be removed by a filter press to remove impurities and remove the impure lime. Then the deacidified and impurity-free water can enter the external water storage tank by opening the valve, and be discharged or reused after passing the sedimentation test.

[0019] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0020] 1. The present invention provides an ultra-pure microcrystalline graphite purification system and a production process thereof. Through the cooperation between the centrifuge sewage pipe and the dryer sewage pipe and the sewage treatment tank, the acid water generated after dehydration by the centrifuge and the excess acid water generated during drying by the dryer will enter the sewage treatment tank and react with lime sticks for neutralization. At the same time, with the immersion in the water reservoir, the discharged acid water will be purified and recycled to avoid environmental pollution.

[0021] 2. The present invention provides an ultrapure microcrystalline graphite purification system and its production process, which is initially purified by flotation and then secondary purified by pickling on both sides with acidic chemicals such as HF, Hc1, HNO3, H2SO4, etc., thereby effectively improving the purity of the graphite.

[0022] 3. The present invention provides an ultra-pure microcrystalline graphite purification system and a production process thereof. Through the cooperation between a centrifuge and a microwave drying oven, the excess acid water after pickling and the moisture generated by drying can be quickly removed, thereby improving the drying quality of the microcrystalline graphite. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the system flow of the present invention;

[0024] Figure 2 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with embodiments:

[0026] Example 1

[0027] like Figure 1 , Figure 2 As shown, the present invention provides an ultra-pure microcrystalline graphite purification system, including a crusher, a grinder, a flotation machine, an acid tank, a reactor, a centrifuge, a dryer, and a sewage treatment tank; the crusher and the grinder are connected by a conveyor belt, the grinder and the flotation machine are connected by a conveying pipe, the flotation machine is connected to the reactor through a pipeline with a valve, the acid tank is connected to the reactor through a pump body, and acid is injected into the inner cavity of the reactor for purification, the reactor is connected to the centrifuge by a pipeline, the centrifuge is connected to the dryer by a pipeline, the centrifuge and the dryer are used to wash and dry the purified graphite to remove residual acid and alkali impurities, the sewage pipe of the centrifuge is fixedly connected to the input end of the sewage treatment tank, and the sewage treatment tank is used to purify the residual acid solution.

[0028] In this embodiment, the centrifuge sewage pipe and the dryer sewage pipe are fixedly connected to the sewage treatment tank, so that the acid water generated after dehydration by the centrifuge and the excess acid water generated during drying by the dryer will enter the sewage treatment tank for purification.

[0029] Example 2

[0030] like Figure 1 , Figure 2 As shown, the present invention provides a process for purifying ultrapure microcrystalline graphite, comprising the following steps:

[0031] Step 1: Raw material preparation, select low ash, high purity aggregate as raw material;

[0032] Step 2: Preliminary purification by flotation, using flotation to remove most impurities and obtain graphite concentrate with a high fixed carbon content;

[0033] Step 3: Deep purification by chemical method, select hydrofluoric acid method to further purify graphite;

[0034] Step 4: Dehydration and drying treatment: dehydration and drying of the purified graphite to remove residual acid and alkali impurities;

[0035] Step 5: Sewage treatment, recycling waste liquid through sewage treatment tanks to reduce waste liquid discharge and environmental pollution.

[0036] Example 3

[0037] like Figure 1 , Figure 2 As shown, on the basis of Example 2, the present invention provides a technical solution: preferably, in step 1, the selected aggregate is preliminarily crushed by a crusher until the particle size is maintained at one centimeter in diameter, and then the crushed aggregate particles are uniformly conveyed to a grinder by a conveyor belt for grinding, and the powder is stopped and kept aside when it becomes powder. In step 2, the powdered aggregate is conveyed to a flotation machine by a pipeline, and a flotation agent is injected into the flotation machine to enrich the selected target mineral at the gas-liquid interface, so as to achieve separation from the impurity minerals and achieve the purpose of purification. The flotation agent includes a collector: coal tar, a foaming agent: pine oil , butyl ether oil, inhibitors: water glass, sodium fluorosilicate, the purity of graphite after preliminary flotation purification can reach 80% to 90%, in step three, by injecting the preliminary purified graphite into the reactor, and adding HF, Hc1, HNO3, H2SO4 in the acid tank in advance, the overall mass ratio is HF: Hc1: HNO3: H2SO4 = 2:2:1:1, and the quantity is determined by observing the capacity scale of the acid tank. After preparation, open the valve and flow into the reactor through the pump body. The reactor is charged with 1 ton of material at a time, which is a batch. Add 600 kg of acid and 300 kg of water. The material can be qualified after two acid washings.

[0038] In this embodiment, after the initial purification by flotation, the graphite is secondary purified by pickling on both sides with acidic chemicals such as HF, Hcl, HNO3, H2SO4, etc., thereby effectively improving the purity of the graphite.

[0039] Example 4

[0040] like Figure 1 , Figure 2As shown, on the basis of Example 2, the present invention provides a technical solution: preferably, the dehydration treatment in step 4 is carried out by injecting the pickled graphite into a centrifuge for dehydration. The centrifuge mainly has a filter cloth inside. The material carries water under the high-speed rotating centrifugal action, and the water passes through the filter cloth and is filtered out. The method of adding water while washing and filtering water is adopted. The filter cloth is 1000 mesh-2000 mesh. At the same time, a certain thickness of material is stained on the filter cloth, and it is not removed for cleaning, so as to increase the resistance to material loss, thereby preventing the loss of fine materials. The centrifuge is charged with 200 kg of material at a time, centrifuged 5 times for one batch, and 5 tons of water are required to wash one ton of graphite. The water content of the centrifuged material is controlled within 25%. The drying treatment in step 4 adopts two-step microwave drying That is, the dehydrated graphite is dried for one hour in a microwave drying oven to remove a certain amount of water, and then the drying is repeated to achieve the purpose of drying. The water content is controlled below 0.05%. In step 5, the sewage treatment tank is used to collect the water during the dehydration of the centrifuge and the water generated during the drying process. The sewage treatment tank is divided into two front and rear chambers, one chamber is an acid water collection chamber, and the other chamber is a neutralization chamber. Several lime sticks are evenly placed in the neutralization chamber and the lime sticks are replaced regularly. The lime sticks can neutralize the acid in the acid water. The neutralized water needs to be removed by a filter press to remove impurities and remove the doped lime. Then the deacidified and impurity-free water can enter the external water storage tank by opening the valve, and be discharged or reused after passing the sedimentation test.

[0041] In this embodiment, the water in the microcrystalline graphite can be quickly removed by a centrifuge and secondary microwave drying, and the water is concentrated in the sewage treatment tank to react with the lime sticks for neutralization. At the same time, the discharged acid water is purified by immersion in a water reservoir, and can be recycled to avoid polluting the environment.

[0042] The above generally describes the present invention in detail, but it is obvious to a person skilled in the art that some modifications or improvements can be made to the present invention. Therefore, modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. An ultrapure microcrystalline graphite purification system, characterized in that: The invention comprises a crusher, a grinder, a flotation machine, an acid tank, a reactor, a centrifuge, a dryer and a sewage treatment tank; the crusher and the grinder are connected by a conveyor belt, the grinder and the flotation machine are connected by a conveying pipe, the flotation machine is connected to the reactor through a pipeline with a valve, the acid tank is connected to the reactor through a pump body, and acid is injected into the inner cavity of the reactor for purification, the reactor is connected to the centrifuge by a pipeline, the centrifuge is connected to the dryer by a pipeline, the purified graphite is washed and dried by the centrifuge and the dryer to remove residual acid and alkali impurities, the sewage pipe of the centrifuge is fixedly connected to the input end of the sewage treatment tank, and the sewage treatment tank is used to purify the residual acid solution.

2. A process for purifying ultrapure microcrystalline graphite, characterized in that: The following steps are involved: Step 1: Raw material preparation, select low ash, high purity aggregate as raw material; Step 2: Preliminary purification by flotation, using flotation to remove most impurities and obtain graphite concentrate with a high fixed carbon content; Step 3: Deep purification by chemical method, select hydrofluoric acid method to further purify graphite; Step 4: Dehydration and drying treatment: dehydration and drying of the purified graphite to remove residual acid and alkali impurities; Step 5: Sewage treatment, recycling waste liquid through sewage treatment tanks to reduce waste liquid discharge and environmental pollution.

3. The ultrapure microcrystalline graphite purification production process according to claim 2, characterized in that: In the step 1, the selected aggregate is initially crushed by a crusher until the particle size is maintained at one centimeter in diameter, and then the crushed aggregate particles are uniformly conveyed to a grinder by a conveyor belt for grinding, and the grinding is stopped and set aside when the aggregate particles become powder.

4. The ultrapure microcrystalline graphite purification production process according to claim 2, characterized in that: In the step 2, the powdered aggregate is transported to a flotation machine through a pipeline, and a flotation agent is injected into the flotation machine to enrich the target mineral selected at the gas-liquid interface, so as to separate it from the impurity minerals and achieve the purpose of purification. The flotation agent includes a collector: coal tar, a foaming agent: pine oil, butyl ether oil, and an inhibitor: water glass, sodium fluorosilicate. After preliminary flotation purification, the purity of graphite can reach 80% to 90%.

5. The ultrapure microcrystalline graphite purification production process according to claim 2, characterized in that: In the step three, the preliminarily purified graphite is injected into the reactor, and HF, Hc1, HNO3, and H2SO4 are added to the acid tank in advance, with an overall mass ratio of HF:Hc1:HNO3:H2SO4=2:2:1:

1. The quantity is determined by observing the capacity scale of the acid tank. When ready, the valve is opened and the mixture flows into the reactor through the pump body. The reactor is charged with 1 ton of material at a time, which is a batch. 600 kg of acid and 300 kg of water are added. The material can be qualified after two acid washings.

6. The ultrapure microcrystalline graphite purification production process according to claim 2, characterized in that: The dehydration treatment in step 4 is carried out by injecting the pickled graphite into a centrifuge for dehydration. The centrifuge mainly has a filter cloth inside. The material carries water under the high-speed rotating centrifugal action, and the water is filtered out through the filter cloth. The method of adding water while washing and filtering is adopted. The filter cloth has a mesh size of 1000-2000. At the same time, a certain thickness of material is stained on the filter cloth, and it is not removed for cleaning to increase the resistance to material loss, thereby preventing the loss of fine materials. The centrifuge is charged with 200 kg of material at a time, and one batch is centrifuged 5 times. It takes 5 tons of water to wash one ton of graphite, and the water content of the centrifuged material is controlled within 25%.

7. The ultrapure microcrystalline graphite purification production process according to claim 2, characterized in that: The drying treatment in step 4 adopts two-step microwave drying, that is, the dehydrated graphite is first dried for one hour in a microwave drying oven to remove a certain amount of moisture, and then the drying is repeated once to achieve the drying purpose, and the moisture content is controlled below 0.05%.

8. The ultrapure microcrystalline graphite purification production process according to claim 2, characterized in that: The sewage treatment box in step five is used to collect moisture during centrifuge dehydration and moisture generated during drying. The sewage treatment box is divided into two front and rear chambers, one chamber is an acid water collection chamber, and the other chamber is a neutralization chamber. Several lime sticks are evenly placed in the neutralization chamber and the lime sticks are replaced regularly. The lime sticks can neutralize the acid in the acid water. The neutralized water needs to be removed by a filter press to remove impurities and remove the impure lime. Then the deacidified and impurity-free water can enter the external water storage tank by opening the valve, and be discharged or reused after passing the sedimentation test.

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