Method for removing carbon powder in chlorine salt electrolyte

Abstract

The invention discloses a method for removing carbon powder in a chlorine salt electrolyte, and relates to the technical field of electrolyte impurity removal. According to the method, after the lithium chloride electrolyte is melted, the carbon removal agent is added into the lithium chloride electrolyte, so that the lithium chloride electrolyte and carbon are subjected to oxidation-reduction reaction, the carbon is oxidized into carbon dioxide or carbon monoxide to be removed, metal copper obtained through reduction can be removed through solid-liquid separation after standing, precipitation and agglomeration, and the reaction removal rate can reach 95% or above; and the obtained electrolyte without carbon can continuously participate in the electrolytic reaction. Therefore, the carbon removal method provided by the invention has the characteristics of being simple, efficient, environment-friendly, suitable for large-scale production and application and the like.

Description

Technical Field

[0001] The invention relates to the technical field of electrolyte impurity removal, in particular to a method for removing carbon powder from a chloride salt electrolyte. Background Art

[0002] At present, the production methods of metallic lithium include vacuum thermal reduction method and molten salt electrolysis method. In the process of large-scale production of metallic lithium, molten salt electrolysis method is still commonly used for preparation. The principle of molten salt electrolysis method is to mix lithium chloride and potassium chloride in a certain proportion and pour them into the electrolytic cell. After heating them to a certain temperature to melt them, electrolysis is carried out at a temperature of about 380-500°C under the action of direct current. During electrolysis, lithium chloride will decompose to produce metallic lithium on the cathode and chlorine gas on the anode. The reactions occurring at the two electrodes are:

[0003] Cathode: Li + +e - →Li(s);

[0004] Anode: Cl - →Cl2(g)+e - ;

[0005] Total reaction: Li + +Cl - →Cl2(g)+Li(s).

[0006] In the process of lithium metal electrolysis, the cathode and anode materials are usually carbonaceous materials as the anode and low-carbon steel as the cathode. As the electrolysis process continues, the carbon anode material is severely corroded and worn due to factors such as long-term high temperature, bubble corrosion, and impurity ions in the electrolyte, causing a large amount of carbon powder to enter the electrolyte. The carbon powder particle size is small and uneven, and it is dispersed in the electrolyte. During the electrolysis process, this not only seriously affects the circulation fluidity of the electrolyte, but the carbon powder on the surface will also affect the collection of lithium metal, making collection more difficult, and ultimately reducing the efficiency of lithium metal electrolysis. It may even undergo side reactions such as doping and solid solution with lithium metal, resulting in an increase in the carbon content in the product, further affecting the quality of lithium metal. Therefore, it is very important to remove the carbon powder in the electrolyte and reuse it in electrolysis production.

[0007] At present, there are three main methods for treating graphite powder in chloride salt: high temperature burning method, air flotation separation method, and filtration method;

[0008] (1) The high-temperature incineration method is to remove carbon powder by burning carbon powder with oxygen at high temperature to generate CO2. This method has high requirements on equipment and is not suitable for large-scale processing.

[0009] (2) The flotation separation method treats carbon powder in chloride salt, mainly because the diffuse bubbles exposed in the molten salt are easily attached to the surface of carbon particles, replacing the molten salt on their surface, reducing their apparent density, and thus floating to the top of the molten salt, which reduces the solid salt content in the topmost carbon material to less than 10wt.%. This method can remove some carbon powder impurities to a certain extent, but the flotation separation method does not treat carbon powder thoroughly.

[0010] (3) The physical filtration method is simple to operate for removing carbon powder. That is, by setting a mesh with a certain particle size, the electrolyte is filtered and reused. However, the physical filtration method has high requirements on the filter material, particle size and filtration air tightness.

[0011] At present, filtration is the most widely used and probably the easiest way to remove carbon powder, but there are also many bottlenecks in the filtration process: (1) Selection of filtration aperture: The particle size distribution of carbon powder in lithium chloride electrolyte after electrolysis is relatively wide, ranging from hundreds of microns to tens of nanometers. We know that the smaller the aperture, the higher the processing difficulty. In addition, if the aperture is large during the filtration process, only larger particles of carbon powder can be filtered, and small particles will remain in the electrolyte, resulting in poor filtration effect. If a smaller aperture is selected, the mesh is easily clogged, resulting in low filtration efficiency. (2) Selection of filter material: Due to the extremely corrosive nature of lithium chloride molten salt electrolyte and the high temperature of 380-500℃, the filter material requirements are very high. Usually, 316L stainless steel sintered mesh is selected. If zirconium oxide or magnesium oxide is selected, the filtration cost will undoubtedly increase; (3) Filtration sealing: It is usually filtered by gravity, pressure filtration, and suction filtration. The filtration equipment usually includes connecting pipes, pumps, etc., which have extremely high sealing requirements.

[0012] Therefore, there is an urgent need to develop a method for removing carbon powder from lithium chloride electrolyte that has the advantages of simple method, high efficiency and convenience, good treatment effect, high safety factor, and large-scale treatment.

[0013] In view of this, the present invention is proposed. Summary of the invention

[0014] The object of the present invention is to provide a method for removing carbon powder from a chloride salt electrolyte, aiming to provide a simple, efficient and large-scale processing method, which can significantly improve the removal rate of carbon powder.

[0015] The present invention is achieved in that:

[0016] In a first aspect, the present invention provides a method for removing carbon powder from a chloride salt electrolyte, comprising: heating and melting a carbon-containing electrolyte sample, and mixing and reacting the sample with a carbon removal agent;

[0017] Wherein, the carbon removal agent is selected from at least one of basic copper carbonate, copper carbonate, copper oxide, carbon dioxide and water vapor.

[0018] In an optional embodiment, the carbon removal agent is selected from at least one of basic copper carbonate, copper carbonate and copper oxide.

[0019] In an optional embodiment, the molar ratio of carbon atoms in the carbon removal agent and the carbon-containing electrolyte sample is controlled to be (0.8-1.5):1.

[0020] In an optional embodiment, the reaction temperature with the carbon removal agent is 400° C.-1000° C., and the reaction time is 0.5 h-5.0 h.

[0021] In an optional embodiment, the reaction temperature with the carbon removal agent is 500°C-800°C, and the reaction time is 1h-3h;

[0022] And / or, during the reaction with the carbon removal agent, the stirring rate is controlled to be 100r / min-500r / min.

[0023] In an optional embodiment, a high temperature reactor with a bottom discharge valve is used for heating and melting, and then mixed with a carbon removal agent for reaction;

[0024] After the reaction is completed, the temperature is lowered to 380°C-450°C, then allowed to stand for 1h-5h, and the bottom discharge valve is opened to remove the bottom precipitate.

[0025] In an optional embodiment, the carbon-containing electrolyte sample is heated to 350° C.-500° C., kept warm for 1 h-3 h after being completely melted, and then mixed with the carbon removal agent for reaction.

[0026] In an optional embodiment, the heating and melting temperature is controlled to be 380°C-450°C.

[0027] In an optional embodiment, before heating and melting the carbon-containing electrolyte sample, the carbon content of the carbon-containing electrolyte sample is analyzed to obtain the initial carbon powder content.

[0028] In an optional embodiment, the carbon-containing electrolyte sample is a lithium chloride-potassium chloride carbon-containing electrolyte, the carbon mass fraction is 0.05wt.%-2wt.%, and the potassium chloride mass fraction is 35wt.%-70wt.%.

[0029] The present invention has the following beneficial effects: after the lithium chloride electrolyte is melted, a carbon remover is added thereto, so that a redox reaction occurs with carbon, and the carbon is oxidized into carbon dioxide or carbon monoxide and removed. The reduced metal element has a high melting point and a large density, and can be removed by settling and agglomerating. The reaction removal rate can reach more than 95%, and the obtained decarbonized electrolyte can continue to participate in the electrolysis reaction. It can be seen that the decarbonization method provided by the present invention has the characteristics of high efficiency, environmental protection, and suitability for large-scale production applications. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0031] In the long-term electrolysis process of metallic lithium in the present invention, the anode graphite is subjected to shedding and erosion corrosion due to high temperature, mechanical corrosion, impurity ion corrosion, etc., and a large amount of carbon powder enters the electrolyte, which has a serious impact on the collection of metallic lithium, the electrolysis efficiency, and the quality of metallic lithium. Therefore, the present invention proposes to use a chemical method to treat the carbon powder impurities in the lithium chloride electrolyte.

[0032] An embodiment of the present invention provides a method for removing carbon powder from a chloride salt electrolyte, comprising the following steps:

[0033] S1. Toner content detection

[0034] The carbon content of the electrolyte sample containing carbon is analyzed to obtain the initial carbon powder content, so as to facilitate the subsequent calculation of the amount of carbon removal agent.

[0035] Specifically, the method for analyzing the carbon content is not limited, such as high temperature ignition weight method, infrared carbon sulfur analyzer analysis method, etc., but not limited to this, other instruments that can perform quantitative analysis can also be used to detect the initial carbon powder content.

[0036] Furthermore, the carbon-containing electrolyte sample is a lithium chloride-potassium chloride carbon-containing electrolyte, in which the mass fraction of carbon is 0.05wt.%-2wt.%, and the mass fraction of potassium chloride is 35wt.%-70wt.%. Potassium chloride is beneficial to lowering the melting point of the electrolyte, and the carbon content and potassium chloride content that meet the above requirements are suitable for carbon removal by the method provided in the embodiment of the present invention.

[0037] S2. Heating and melting

[0038] The carbon-containing electrolyte sample is heated and melted to facilitate the subsequent mixing reaction with the carbon removal agent.

[0039] In some embodiments, the carbon-containing electrolyte sample is heated to 350°C-500°C, and after being completely melted, it is kept warm for 1h-3h to remove excess water and oxyacid ions such as carbonate and sulfate to prevent side reactions with the carbon removal agent. By adjusting the heating temperature, the carbon-containing electrolyte sample is completely melted, and after being kept warm, water and oxyacid ions such as carbonate and sulfate are removed, which is conducive to further increasing the carbon removal rate.

[0040] Specifically, when heating and melting, the heating temperature can be controlled to be 350° C., 380° C., 400° C., 420° C., 450° C., 480° C., 500° C., etc. The heat preservation time after complete melting can be 1 h, 2 h, 3 h, etc.

[0041] In a preferred embodiment, the heating and melting temperature is controlled to be 380° C.-450° C. Within this temperature range, the electrolyte can be melted quickly, and moisture and oxygen acid ions can be effectively removed by heat preservation.

[0042] In some embodiments, a high temperature reactor with a bottom discharge valve can be used for heating and melting. After the mixture is completely melted, it is kept warm for a period of time and then mixed with the carbon removal agent for reaction. The high temperature reactor with a bottom discharge valve is convenient for heating and melting, and is also convenient for separating the sediment after the subsequent reaction is completed.

[0043] S3, mixed reaction with carbon removal agent

[0044] After the heat preservation in step S2 is completed, the temperature is raised and a certain amount of carbon removal agent is added for mixed reaction.

[0045] Furthermore, the carbon remover is selected from at least one of basic copper carbonate [Cu2(OH)2CO3], copper carbonate [CuCO3], copper oxide [CuO], carbon dioxide and water vapor, and the carbon remover can be any one or more of the above. The working principle of basic copper carbonate [Cu2(OH)2CO3], copper carbonate [CuCO3], copper oxide [CuO] as a carbon remover is as follows:

[0046] Cu2(OH)2CO3→2CuO+CO2+H2O;

[0047] CuCO3 → CuO + CO2;

[0048] C+2CuO→2Cu↓+CO2ΔG=(-1533064~-3091169J / mol T=100-1000℃);

[0049] C+CO2→2COΔG=(-8495.7~-51924.2J / mol T=750-1000℃);

[0050] C+H2O→CO+H2ΔG=(-3717.8~-46739.9J / mol T=700-1000℃).

[0051] It should be noted that during the reaction, a redox reaction occurs with carbon, and the carbon is oxidized into carbon dioxide or carbon monoxide and removed. The reduced metal element has a higher melting point and a larger density, so it can be removed by static precipitation and agglomeration.

[0052] In a preferred embodiment, the carbon remover is selected from at least one of basic copper carbonate, copper carbonate and copper oxide. The carbon remover can be any one or two of the above. By optimizing the type of carbon remover, it is beneficial to further improve the carbon removal effect.

[0053] Furthermore, in order to further improve the carbon removal effect, the molar ratio of carbon removal agent and carbon atoms in the carbon-containing electrolyte sample is controlled to be (0.8-1.5):1, such as 0.8:1, 1.0:1, 1.2:1, 1.5:1, etc. It is advisable to control the amount of carbon removal agent within the above range, which is conducive to improving the carbon removal effect, while making the amount of carbon removal agent as small as possible to avoid the introduction of impurities.

[0054] Further, the reaction temperature with the carbon removal agent is 400°C-1000°C, such as 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, etc.; the reaction time is 0.5h-5.0h, such as 0.5h, 1.0h, 2.0h, 3.0h, 4.0h, 5.0h, etc. In a preferred embodiment, the reaction temperature with the carbon removal agent is 500°C-800°C, and the reaction time is 1h-3h. By further adjusting the reaction temperature and time, the reaction is fully carried out and the carbon removal rate is further improved.

[0055] In some embodiments, during the reaction with the carbon removal agent, the stirring rate is controlled to be 100r / min-500r / min, such as 100r / min, 200r / min, 300r / min, 400r / min, 500r / min, etc., and the stirring is stopped after the reaction is completed.

[0056] S4. Separation and precipitation

[0057] After the reaction in step S3 is completed, the temperature of the reactor is lowered, and the reactor is allowed to stand for a period of time to separate the precipitate.

[0058] In some embodiments, after the reaction in step S3 is completed, the temperature is lowered to 380°C-450°C, and then allowed to stand for 1h-5h to allow the solid material to fully settle. Specifically, the temperature after cooling can be 380°C, 400°C, 420°C, 450°C, etc., and the standing time can be 1h, 2h, 3h, 4h, 5h, etc.

[0059] When a high-temperature reactor with a bottom discharge valve is used for the reaction, the bottom discharge valve can be opened after the standing is completed to remove the bottom precipitate, thereby obtaining a lithium chloride electrolyte with a higher purity.

[0060] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0061] It should be noted that the composition of the lithium chloride and potassium chloride carbon-containing electrolytes treated in the following examples and comparative examples is as follows: the carbon mass fraction is 0.05wt.%-2wt.%, the lithium chloride mass fraction is 30-65wt.%, and the potassium chloride mass fraction is 35wt.%-70wt.%.

[0062] Example 1

[0063] This embodiment provides a method for removing carbon powder from a chloride salt electrolyte, comprising the following steps:

[0064] A small amount of lithium chloride and potassium chloride carbon electrolyte in a metal lithium electrolytic cell (current efficiency is about 72.14%) is taken, and the carbon content is analyzed by infrared carbon-sulfur analyzer, and the mass ratio of carbon powder is preliminarily obtained to be 0.64wt.%. A certain mass of lithium chloride and potassium chloride carbon electrolyte mixture is placed in a heating furnace, and the heating temperature is set to 380°C. After the carbon electrolyte is completely melted, it is kept warm for 1 hour, and a certain amount of basic copper carbonate is added, and the molar ratio of basic copper carbonate to carbon powder is controlled to be 0.8:1 (that is, the molar ratio of oxygen atoms in the carbon remover to carbon atoms in the lithium chloride and potassium chloride carbon electrolyte is controlled to be 4:1), and the temperature is raised to 500°C, and stirring is started at the same time (the stirring rate is controlled to be 300r / min, the same below), and after the reaction for 1 hour, the reaction temperature is lowered to 400°, and then after standing for 1 hour for solid-liquid separation, the discharge valve at the bottom of the heating furnace is opened to discharge the bottom sediment.

[0065] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.06%, and the mass fraction of copper element was 0.009wt.%. The electrolyte after impurity removal was returned to the electrolytic cell for electrolysis for a period of time, and the current efficiency was about 82.56%.

[0066] Example 2

[0067] This embodiment provides a method for removing carbon powder from a chloride salt electrolyte, comprising the following steps:

[0068] Take a small amount of lithium chloride potassium chloride carbon electrolyte in a metal lithium electrolytic cell (current efficiency is about 68.42%), analyze its carbon content using an infrared carbon-sulfur analyzer, and preliminarily obtain that the mass proportion of carbon powder is 0.82wt.%. Weigh a certain mass of lithium chloride potassium chloride carbon electrolyte mixture in a heating furnace, set the heating temperature to 400°C, and keep it warm for 1h after the carbon electrolyte is completely melted. Add a certain amount of basic copper carbonate, control the molar ratio of basic copper carbonate to carbon powder to 1:1 (that is, control the molar ratio of oxygen atoms in the carbon remover to carbon atoms in the lithium chloride potassium chloride carbon electrolyte to 5:1), increase the temperature to 600°C, and start stirring at the same time. After reacting for 2h, reduce the reaction temperature to 400°, and stand for 1h for solid-liquid separation, open the discharge valve at the bottom of the heating furnace, and discharge the bottom sediment.

[0069] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.34%, and the mass fraction of copper element was 0.008wt.%. The electrolyte after impurity removal was returned to the electrolytic cell for electrolysis for a period of time, and the current efficiency was about 81.37%.

[0070] Example 3

[0071] This embodiment provides a method for removing carbon powder from a chloride salt electrolyte, comprising the following steps:

[0072] Take a small amount of lithium chloride potassium chloride carbon electrolyte in a metal lithium electrolytic cell (current efficiency is about 68.85%), analyze its carbon content using an infrared carbon-sulfur analyzer, and preliminarily obtain that the mass proportion of carbon powder is 0.75wt.%. Weigh a certain mass of lithium chloride potassium chloride carbon electrolyte mixture in a heating furnace, set the heating temperature to 400°C, and keep it warm for 1h after the carbon electrolyte is completely melted. Add a certain amount of basic copper carbonate, control the molar ratio of basic copper carbonate to carbon powder to 1.2:1 (that is, control the molar ratio of oxygen atoms in the carbon remover to carbon atoms in the lithium chloride potassium chloride carbon electrolyte to 6:1), increase the temperature to 600°C, and start stirring at the same time. After reacting for 3h, reduce the reaction temperature to 400°, and stand for 2h for solid-liquid separation, open the discharge valve at the bottom of the heating furnace, and discharge the bottom sediment.

[0073] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 96.42%, and the mass fraction of copper element was 0.006wt.%. The electrolyte after impurity removal was returned to the electrolytic cell for electrolysis for a period of time, and the current efficiency was about 81.06%.

[0074] Example 4

[0075] This embodiment provides a method for removing carbon powder from a chloride salt electrolyte, comprising the following steps:

[0076] Take a small amount of lithium chloride potassium chloride carbon electrolyte in a metal lithium electrolytic cell (current efficiency is about 66.05%), analyze its carbon content using an infrared carbon-sulfur analyzer, and preliminarily obtain that the mass proportion of carbon powder is 0.87wt.%. Weigh a certain mass of lithium chloride potassium chloride carbon electrolyte mixture in a heating furnace, set the heating temperature to 400°C, and keep it warm for 1h after the carbon electrolyte is completely melted. Add a certain amount of basic copper carbonate, control the molar ratio of basic copper carbonate to carbon powder to 1.2:1 (that is, control the molar ratio of oxygen atoms in the carbon remover to carbon atoms in the lithium chloride potassium chloride carbon electrolyte to 6:1), increase the temperature to 800°C, and start stirring at the same time. After reacting for 3h, reduce the reaction temperature to 400°, and stand for 3h for solid-liquid separation, open the discharge valve at the bottom of the heating furnace, and discharge the bottom sediment.

[0077] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 96.53%, and the mass fraction of copper element was 0.005wt.%. The electrolyte after impurity removal was returned to the electrolytic cell for electrolysis for a period of time, and the current efficiency was about 85.21%.

[0078] Example 5

[0079] This embodiment provides a method for removing carbon powder from a chloride salt electrolyte, comprising the following steps:

[0080] Take a small amount of lithium chloride potassium chloride carbon electrolyte in a metal lithium electrolytic cell (current efficiency is about 56.84%), analyze its carbon content using an infrared carbon-sulfur analyzer, and preliminarily obtain that the mass proportion of carbon powder is 0.94wt.%. Weigh a certain mass of lithium chloride potassium chloride carbon electrolyte mixture in a heating furnace, set the heating temperature to 380°C, and keep it warm for 2h after the carbon electrolyte is completely melted. Add a certain amount of basic copper carbonate, control the molar ratio of basic copper carbonate to carbon powder to 1.5:1 (that is, control the molar ratio of oxygen atoms in the carbon remover to carbon atoms in the lithium chloride potassium chloride carbon electrolyte to 7.5:1), increase the temperature to 800°C, and start stirring at the same time. After reacting for 3h, reduce the reaction temperature to 400°, and stand for 1h for solid-liquid separation, open the discharge valve at the bottom of the heating furnace, and discharge the bottom sediment.

[0081] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.82%, and the mass fraction of copper element was 0.007wt.%. The electrolyte after impurity removal was returned to the electrolytic cell for electrolysis for a period of time, and the current efficiency was about 79.68%.

[0082] Example 6

[0083] This embodiment provides a method for removing carbon powder from a chloride salt electrolyte, comprising the following steps:

[0084] Take a small amount of lithium chloride potassium chloride carbon electrolyte in a metal lithium electrolytic cell (current efficiency is about 42.39%), analyze its carbon content using an infrared carbon-sulfur analyzer, and preliminarily obtain that the mass proportion of carbon powder is 1.20wt.%. Weigh a certain mass of lithium chloride potassium chloride carbon electrolyte mixture in a heating furnace, set the heating temperature to 400°C, and keep it warm for 2h after the carbon electrolyte is completely melted. Add a certain amount of basic copper carbonate, control the molar ratio of basic copper carbonate to carbon powder to 1:1 (that is, control the molar ratio of oxygen atoms in the carbon remover to carbon atoms in the lithium chloride potassium chloride carbon electrolyte to 5:1), increase the temperature to 800°C, and start stirring at the same time. After reacting for 3h, reduce the reaction temperature to 400°, and stand for 1h for solid-liquid separation, open the discharge valve at the bottom of the heating furnace, and discharge the bottom sediment.

[0085] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.46%, and the mass fraction of copper element was 0.008wt.%. The electrolyte after impurity removal was returned to the electrolytic cell for electrolysis for a period of time, and the current efficiency was about 75.48%.

[0086] Example 7

[0087] The only difference from Example 4 is that the molar ratio of basic copper carbonate to carbon powder is controlled to be 1.5 wt.%.

[0088] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 96.82wt.%, the copper element mass fraction was 0.012wt.%, and the current efficiency was about 86.36%.

[0089] Example 8

[0090] The only difference from Example 4 is that the molar ratio of basic copper carbonate to carbon powder is controlled to be 0.8 wt.%.

[0091] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.21wt.%, the copper element mass fraction was 0.002wt.%, and the current efficiency was about 82.27%.

[0092] Example 9

[0093] The only difference from Example 4 is that basic copper carbonate is replaced by copper carbonate, and the added amount of oxygen atoms of the carbon remover is kept consistent with that of Example 4.

[0094] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.82wt.%, the copper element mass fraction was 0.005wt.%, and the current efficiency was about 82.49%.

[0095] Example 10

[0096] The only difference from Example 4 is that basic copper carbonate is replaced by copper oxide, and the added amount of oxygen atoms of the carbon remover is kept consistent with that of Example 4.

[0097] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.24wt.%, the copper element mass fraction was 0.004wt.%, and the current efficiency was about 81.73%.

[0098] Embodiment 11

[0099] The only difference from Example 4 is that the reaction temperature after adding the carbon removal agent is 1000°C.

[0100] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 97.25%, the mass fraction of copper element was 0.002wt.%, and the current efficiency was about 83.58%.

[0101] Example 12

[0102] The only difference from Example 4 is that the reaction temperature after adding the carbon removal agent is 400°C.

[0103] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 64.59wt.%, the copper element mass fraction was 0.32wt.%, and the current efficiency was about 68.41%.

[0104] Example 13

[0105] The only difference from Example 4 is that the carbon content of the carbon-containing electrolyte in the metallic lithium electrolyte (the current efficiency is only 26.85%) is analyzed, and the mass proportion of carbon powder is 1.58wt.%.

[0106] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.26wt.%, the copper element mass fraction was 0.025wt.%, and the current efficiency was about 76.48%.

[0107] Embodiment 14

[0108] The only difference from Example 4 is that the carbon content of the carbon-containing electrolyte in the metallic lithium electrolyte (the current efficiency is only 12.46%) is analyzed, and the mass proportion of carbon powder is 1.84wt.%.

[0109] Detection after impurity removal: A small amount of the treated electrolyte was taken for carbon content analysis and ICP analysis, and the final carbon removal rate was 95.02wt.%, the copper element mass fraction was 0.034wt.%, and the current efficiency was about 75.19%.

[0110] In summary, the embodiment of the present invention provides a method for removing carbon powder in a chloride salt electrolyte, which has the following advantages compared to the traditional process:

[0111] (1) Simple and efficient: Copper oxide and carbon powder react easily under these conditions. The carbon dioxide and water vapor produced can not only react further with the carbon powder, but also disturb and promote the reaction, accelerating the reaction. The entire reaction process is simple and efficient, and the required equipment is also easy to implement.

[0112] (2) Large processing capacity: It can process tons of carbon-containing electrolytes at one time, which is easy to process on an industrial scale.

[0113] (3) Obvious effect: The removal rate of carbon powder impurities in the treated lithium chloride electrolyte can reach more than 95%, and the effect is obvious. After treatment, the current efficiency is significantly improved and can be directly returned to the electrolytic cell for continued electrolysis.

[0114] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for removing carbon powder from a chloride electrolyte, characterized in that: include: The electrolyte sample containing carbon is heated and melted, and mixed with the carbon removal agent for reaction; Wherein, the carbon removal agent is selected from at least one of basic copper carbonate, copper carbonate, copper oxide, carbon dioxide and water vapor.

2. The method according to claim 1, characterized in that: The carbon remover is selected from at least one of basic copper carbonate, copper carbonate and copper oxide.

3. The method according to claim 1, characterized in that The molar ratio of carbon atoms in the carbon remover and the carbon-containing electrolyte sample is controlled to be (0.8-1.5):

1.

4. The method according to claim 3, characterized in that The reaction temperature with the carbon removal agent is 400° C.-1000° C., and the reaction time is 0.5 h-5.0 h.

5. The method according to claim 4, characterized in that The reaction temperature with the carbon removal agent is 500°C-800°C, and the reaction time is 1h-3h; And / or, during the reaction with the carbon removal agent, the stirring rate is controlled to be 100 r / min-500 r / min.

6. The method according to any one of claims 1 to 5, characterized in that A high-temperature reaction kettle with a bottom discharge valve is used for heating and melting, and then mixed with the carbon removal agent for reaction; After the reaction is completed, the temperature is lowered to 380°C-450°C, then allowed to stand for 1h-5h, and the bottom discharge valve is opened to remove the bottom precipitate.

7. The method according to claim 1, characterized in that The carbon-containing electrolyte sample is heated to 350° C.-500° C., kept warm for 1 h-3 h after being completely melted, and then mixed with the carbon removal agent for reaction.

8. The method according to claim 7, characterized in that The heating and melting temperature is controlled to be 380°C-450°C.

9. The method according to claim 1, characterized in that: Before the carbon-containing electrolyte sample is heated and melted, the carbon content of the carbon-containing electrolyte sample is analyzed to obtain the initial carbon powder content.

10. The method according to claim 1, characterized in that The carbon-containing electrolyte sample is a lithium chloride-potassium chloride carbon-containing electrolyte, the carbon mass fraction is 0.05wt.%-2wt.%, and the potassium chloride mass fraction is 35wt.%-70wt.%.