Electrolytic cathode carbon soluble villiaumite extraction device

Abstract

The utility model discloses a device for extracting soluble villiaumite from electrolytic cathode carbon, which belongs to the technical field of electrolytic cathode carbon recycling equipment, and particularly structurally comprises a pulverizer, a melting device, an extractor and a crystallizer, a discharge port of the pulverizer is connected to a feed port of the melting device, a discharge port of the melting device is connected to a feed port of the extractor, and a discharge port of the extractor is connected to a discharge port of the crystallizer. A discharge port of the leacher is connected to a feed port of the crystallizer, and the crystallizer is connected to the leacher through a circulation loop. According to the utility model, the pretreated waste cathode is subjected to pulverization and melting calcination treatment, insoluble fluorine in the waste cathode is converted into soluble villiaumite, then the soluble villiaumite is extracted by adopting the crystallizer, inorganic fluoride is removed from a waste cathode carbon block, so that the cathode carbon powder is harmless, and the recycling of the cathode carbon powder is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of electrolytic cathode carbon recovery and processing equipment, and in particular relates to a device for extracting soluble fluoride salt from electrolytic cathode carbon. Background Art

[0002] The average life of electrolytic cells currently in operation is 2000-2600 days, after which the electrolytic cells need to be overhauled before electrolytic production can resume.

[0003] Since fluoride salts need to be added during the aluminum electrolysis production process, about 20-35 kg of fluoride salts need to be added for each ton of aluminum electrolysis production. Part of the fluoride enters the atmosphere in gaseous form, and the other part remains in the lining of the electrolytic cell. Fluoride accounts for about 36% of the waste lining, among which the soluble fluoride in each ton of overhaul slag reaches 16.4-56 kg. Therefore, the concentration of fluoride in the electrolytic cell overhaul slag after water leaching is very high and highly alkaline. This waste slag is very harmful to the environment. If it is not properly disposed, it will pollute the soil and groundwater.

[0004] According to the data of electrolytic cell overhaul slag from similar enterprises, the fluoride concentration of the leachate in each component is as high as 2200 mg / L, and the cyanide content is above 8 mg / L. According to the "Identification of Hazardous Waste Identification Standards for Leaching Toxicity Identification" (GB 5085.3 - 2007), if the fluoride concentration of the waste slag leachate exceeds the concentration limit of 100 mg / L specified in the standard, the electrolytic cell overhaul slag is a hazardous waste with leaching toxicity.

[0005] The main domestic methods for disposing of electrolytic cell overhaul slag include rotary kiln roasting treatment, cement kiln coordinated treatment, bauxite sintering, flotation treatment, lime water soaking treatment, etc.

[0006] However, the carbon content of the waste cathode carbon blocks after pretreatment is relatively high, which can reach more than 65%. The carbon therein is a material that has been roasted and roasted at high temperature for a long time in the electrolytic cell. In addition, graphitized and graphite cathodes are gradually being used at home and abroad. Therefore, removing inorganic fluorides from waste cathode carbon blocks has great resource utilization value. Summary of the invention

[0007] The technical problem to be solved by the utility model is to provide a device for extracting soluble fluoride salt from electrolytic cathode carbon, so as to remove inorganic fluoride from waste cathode carbon blocks and render cathode carbon powder harmless.

[0008] The technical solution adopted by the utility model is: an electrolytic cathode carbon soluble fluoride salt extraction device, comprising a grinder, a melting device, a leacher and a crystallizer, the discharge port of the grinder is connected to the feed hole of the melting device, the discharge port of the melting device is connected to the feed port of the leacher, the discharge port of the leacher is connected to the feed port of the crystallizer, and the crystallizer is connected to the leacher through a circulation loop.

[0009] Furthermore, the feed port of the grinding mill is connected to a feeding belt conveyor, and the discharge port is connected to a feed hole of the melting equipment through a screw conveyor.

[0010] Furthermore, the discharge port of the above-mentioned melting equipment is connected to the feed port of the extractor through a chain conveyor, and the melting equipment is also provided with a soda ash addition port.

[0011] Furthermore, the discharge port of the above-mentioned extractor is connected to the feed port of the crystallizer through a delivery pump and a pipeline, the extractor is connected to the feed pump through a pipeline, the feed pump is connected to the additive storage tank, the crystallizer is connected to the feed port of the extractor through a circulation pipe and a circulation pump, the crystallizer is connected to the crystallizer addition pump through a pipeline, and the crystallizer addition pump is connected to the crystallizer storage tank.

[0012] Furthermore, the crushing particle size range of the above-mentioned grinding mill is 100~600 mesh.

[0013] The beneficial effects of the utility model are as follows: compared with the prior art, the present invention processes the pretreated waste cathode through powder making and melt calcination, converts the insoluble fluorine therein into soluble fluoride salt, and then uses a crystallizer to extract the soluble fluoride salt, thereby achieving efficient extraction of the soluble fluoride salt, recycling the inorganic fluoride in the waste cathode, rendering the cathode carbon powder harmless, and also achieving high-purity recycling of the cathode carbon powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of the device for extracting soluble fluoride salt from electrolytic cathode carbon;

[0015] Figure 2 Schematic diagram of the process of extracting soluble fluoride salts using concentration difference crystallization. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] Example 1: Figure 1 As shown, an electrolytic cathode carbon soluble fluoride salt extraction device includes a grinding mill 1, a melting device 2, a leaching device 3 and a crystallizer 4, the discharge port of the grinding mill 1 is connected to the feed hole of the melting device 2, the discharge port of the melting device 2 is connected to the feed port of the leaching device 3, the discharge port of the leaching device 3 is connected to the feed port of the crystallizer 4, and the crystallizer 4 is connected to the leaching device 3 through a circulation loop.

[0018] Among them, the feed port of the above-mentioned grinding mill 1 is connected to a feeding belt conveyor (or manual feeding), and the discharge port is connected to the feed hole of the melting equipment 2 (or manual feeding) through a screw conveyor. The discharge port of the grinding mill 1 is provided with a valve. When the valve is opened, the powder falls out and falls into the feed hopper of the screw conveyor. The discharge port of the screw conveyor is connected to the feed hole of the melting equipment 2. The spiral conveying can reduce dust flying and improve the working environment.

[0019] The discharge port of the melting device 2 is connected to the feed port of the extractor 3 through a chain conveyor. The melting device 2 is also provided with a soda ash addition port, and the discharge port is provided with a valve plate. After the valve plate is opened, the melting device melts the material in the form of coal slag after adding soda ash, and feeds it into the extractor through a chain conveyor (or manual feeding).

[0020] The discharge port of the extractor 3 is connected to the feed port of the crystallizer 4 through a delivery pump and a pipeline (installed with a valve), the extractor 3 is connected to the feed pump through a pipeline (installed with a valve), the feed pump is connected to the additive storage box, the crystallizer 4 is connected to the feed port of the extractor 3 through a circulation pipe (installed with a valve) and a circulation pump, which can realize multiple leaching and multiple crystallization of the crystallization liquid and increase the output of crystalline fluoride salt. The crystallizer 4 is connected to the crystallizer addition pump through a pipeline, and the crystallizer addition pump is connected to the crystallizer storage box, which can realize the addition of crystallizer, and can also be added manually.

[0021] The crushing particle size of the grinding mill 1 ranges from 100 to 600 meshes, which can achieve optimal mixing with soda ash and melt to produce a chemical reaction.

[0022] The utility model treats the pretreated waste cathode by powdering and melting calcination to convert the insoluble fluorine therein into soluble fluoride salt, and then extracts the soluble fluoride salt by concentration difference crystallization method to make the cathode carbon powder harmless.

[0023] Example 2: An extraction method of a soluble fluoride salt extraction device for electrolytic cathode carbon, the method is as follows: the waste cathode carbon from the overhaul of aluminum electrolysis is ground by a grinder 1 and sent to a melting device 2 for high-temperature melting, and the molten melt enters a leacher 3, in which the soluble fluoride salt is dissolved into the liquid, and then the fluorine-containing solution enters a crystallizer 4, and the fluorine-containing substance in the crystallizer 4 with the addition of a crystallizer crystallizes on the solid wall surface, and the crystallized solution is recycled back to the leaching process, and the waste cathode carbon and the solid CaF2 and soda ash therein are calcined at high temperature (600-900°C) in the melting device to convert the insoluble fluorine therein into a soluble fluoride salt. Chemical reaction formula:

[0024] Na2CO3+CaF2→CaCO3+2NaF

[0025] Na2CO3+CaF2→CaO+2NaF + CO2↑

[0026] In the high temperature melting and roasting process, the proportion of components is:

[0027] Soda ash: waste cathode powder = 0.4~1.2:1.

[0028] The crushing particle size range of the grinding mill 1 is 100-600 mesh, and the best material consumption ratio is 250 mesh.

[0029] The ground material is added with soda ash and calcined at high temperature (600-900°C) to convert the insoluble fluorine into soluble fluoride salt.

[0030] The crystallization agent is NaOH for adjusting the pH value of the fluorine-containing solution, and the pH value of the fluorine-containing solution is 9-13.

[0031] The leaching agent is an acidic substance (such as manganese sulfate) for adjusting the pH value of the solution. The pH value of the solution is 8-9, so that the circulated solution can be as close to this pH value range as possible to achieve efficient leaching; the leaching process adopts a multi-stage reverse leaching method to efficiently leach soluble fluoride salts.

[0032] Through multiple cycles of adjustment of acidic and alkaline substances, the change of concentration difference is achieved to adjust leaching and crystallization, thereby improving the recovery rate of soluble fluoride salts.

[0033] Through experiments, as shown in the following table:

[0034]

[0035] As can be seen from the table, by adding caustic soda (Na2OH, etc.) to reduce the saturation concentration in the solution, F- can be crystallized and fluoride salts can be precipitated in the primary washing solution. Similarly, by reducing the caustic soda, the leaching rate of soluble F- can be greatly increased in the leaching process.

[0036] The above description is only a specific implementation method of the present utility model, but the protection scope of the present utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present utility model, which should be included in the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be based on the protection scope of the claims.

Claims

1. An electrolytic cathode carbon soluble fluoride salt extraction device, characterized in that: The invention comprises a grinding mill (1), a melting device (2), an extractor (3) and a crystallizer (4), wherein the discharge port of the grinding mill (1) is connected to the feed hole of the melting device (2), the discharge port of the melting device (2) is connected to the feed port of the extractor (3), the discharge port of the extractor (3) is connected to the feed port of the crystallizer (4), and the crystallizer (4) is connected to the extractor (3) via a circulation loop.

2. The device for extracting soluble fluoride salt from electrolytic cathode carbon according to claim 1, characterized in that: The feed port of the grinding mill (1) is connected to a feeding belt conveyor, and the discharge port is connected to a feed hole of the melting device (2) via a screw conveyor.

3. The device for extracting soluble fluoride salt from electrolytic cathode carbon according to claim 1, characterized in that: The discharge port of the melting device (2) is connected to the feed port of the extractor (3) via a chain conveyor, and the melting device (2) is also provided with a soda ash addition port.

4. The device for extracting soluble fluoride salt from electrolytic cathode carbon according to claim 1, characterized in that: The discharge port of the extractor (3) is connected to the feed port of the crystallizer (4) through a delivery pump and a pipeline, the extractor (3) is connected to the feed pump through a pipeline, the feed pump is connected to the additive storage tank, the crystallizer (4) is connected to the feed port of the extractor (3) through a circulation pipe and a circulation pump, the crystallizer (4) is connected to the crystallizer addition pump through a pipeline, and the crystallizer addition pump is connected to the crystallizer storage tank.

5. The device for extracting soluble fluoride salt from electrolytic cathode carbon according to claim 1, characterized in that: The crushing particle size range of the grinding mill (1) is 100-600 mesh.

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