A method for producing lithium sulfide powder by direct combination of vapor

Abstract

The application provides a method for producing lithium sulfide powder by direct combination of vapors, and relates to the technical field of functional material production. The method for producing lithium sulfide powder by direct combination of vapors comprises the following steps: under the protection of inert gas, lithium and sulfur or a sulfur-containing substance are heated respectively to form vapors; lithium vapor and sulfur vapor are directly combined to generate lithium sulfide powder; the lithium sulfide powder, unreacted sulfur vapor or lithium vapor are blown into a dust collector by a circulating fan in a synthesis system; lithium sulfide powder and secondary dust collection tail gas are obtained through the dust collector; the secondary dust collection tail gas is returned to a lithium vapor conveying pipe; the lithium vapor is circulated in the synthesis system under the action of the circulating fan; and the synthesized lithium sulfide powder is vacuum heated to remove residual trace elemental sulfur to obtain product lithium sulfide powder. The method is simple in process, uniform in particle size of the prepared lithium sulfide powder, controllable in particle size, safe and environmentally friendly in the preparation process, wide in application range, and beneficial to industrial production practice and popularization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional material production, and in particular to a method for producing lithium sulfide powder by direct combination of vapor. BACKGROUND

[0002] Compared with lithium ion batteries, lithium-sulfur batteries have ultra-high energy density, environmental friendliness, high safety and low cost, and have become one of the most potential power batteries of the next generation.

[0003] Recently, Toyota Motor Corporation and Japan's Idemitsu Kosan Petroleum Company announced that they would cooperate in the mass production of all-solid-state batteries for pure electric vehicles, aiming to make all-solid-state batteries practical in 2027-2028. According to the South Korean new energy analysis agency SNE, all-solid-state batteries produced from 2027 will account for 10-13% of the entire market share by 2035.

[0004] As a key raw material for synthesizing solid-state sulfide electrolyte or as an electrode material for lithium-sulfur battery packs, the production technology development and commercial application of lithium sulfide have been increasingly concerned and valued. Lithium sulfide can be divided into battery grade (≥99.99%) and industrial grade (96%) according to purity, and is purchased in batches according to kilogram level. The domestic battery grade lithium sulfide is more than 5000 yuan / kg, and part of the imported lithium sulfide is more than 8000 yuan / kg.

[0005] Although the theoretical specific capacity of lithium sulfide is as high as 1167mAh·g -1 , the energy density of lithium-sulfur batteries can theoretically reach more than 600Wh / kg. However, lithium sulfide has very active chemical properties, and the manufacturing and storage conditions are strict. At present, the methods for synthesizing lithium sulfide can be roughly divided into direct synthesis method, ball milling method, solvent method, and high temperature and high pressure method.

[0006] The direct synthesis method is a method for directly combining lithium-containing compounds with sulfur-containing compounds, elemental lithium with sulfur-containing compounds, or lithium-containing compounds with elemental sulfur to produce lithium sulfide. However, the lithium sulfide particles produced after the reaction are large, have poor electrochemical performance, and have short cycle life and other defects. For example, Chinese patent CN114195103A discloses a preparation method of alkali metal and alkaline earth metal sulfide, and the raw material is selected as a substance containing alkali metal or alkaline earth metal and thiourea. Thiourea is flammable and explosive as an organic substance, which is not conducive to environmental protection and safe operation, and the prepared lithium sulfide has many impurities. Chinese patent CN111517288A discloses a method for synthesizing lithium sulfide, which uses lithiumized solution and elemental sulfur as raw materials, and also uses organic solvent, and the prepared lithium sulfide also has many impurities.

[0007] Ball milling method is to mechanically ball mill lithium source and sulfur source to synthesize lithium sulfide in a protective atmosphere, but the ball milling process will introduce impurities to affect the purity and performance of the prepared lithium sulfide powder. Chinese patent CN112777571A discloses a method for synthesizing battery-grade lithium sulfide, the raw materials are pure lithium and sulfur powder, and impurities will be introduced into the raw materials during the process of plasma ball milling and crushing and granulation. Moreover, the pure lithium and sulfur powder will undergo a melting reaction during the calcination process, and the reaction between the two melts is not sufficient, and the utilization rate of the raw materials is not high. Chinese patent CN104609376A discloses a preparation method of lithium sulfide powder, the raw materials are lithium sulfide powder and sulfur powder, and ball milling will introduce impurities and residual raw materials into the lithium sulfide powder.

[0008] The solvent method is to dissolve lithium or lithium-containing compounds, sulfur or sulfur-containing compounds in a solvent, and then add sulfur or sulfur-containing compounds, lithium or lithium-containing compounds to mix and react to prepare lithium sulfide. Lithium or lithium-containing compounds and sulfur or sulfur-containing compounds can also be dissolved in the same solvent to react to prepare lithium sulfide. The solvent is usually selected from organic solvents or liquid ammonia; the organic solvent is usually selected from aliphatic hydrocarbons, aromatic hydrocarbons or ether solvents, etc., such as ethanol, hexane, toluene, diethyl ether, tetrahydrofuran, methyl pyrrolidone, etc. Chinese patent CN105016310A discloses a preparation method of high-purity lithium sulfide, which is to first prepare a lithium hydrosulfide slurry by mixing lithium hydroxide with N-methyl pyrrolidone and then introducing hydrogen sulfide, and then removing hydrogen sulfide and impurities to obtain high-purity lithium sulfide. This method has the technical defects of long reaction time, high reaction temperature, fast consumption of starting materials, and serious product pollution.

[0009] The high-temperature and high-pressure method is to use high temperature and high pressure to make lithium or lithium compounds and sulfur or sulfur compounds combine to react to prepare lithium sulfide in an inert or reducing atmosphere; or to use a reducing agent to reduce a sulfur-containing lithium compound to obtain lithium sulfide. Chinese patent CN106229487A discloses a method for preparing a carbon / sulfur-lithium composite positive electrode material for lithium-sulfur batteries by carbon thermal reduction of lithium sulfate. The preparation method involves an organic solvent, and the prepared lithium sulfide has many impurities. Chinese patent CN102177090A discloses a preparation method of lithium sulfide, which involves heating one or more lithium-containing compounds and sulfur, wherein the heating step is carried out at a temperature of 600°C to 1500°C. The sulfur evaporates during the heating process, and the product composition is complex and has many impurities. Chinese patent CN108190845A discloses a method for preparing lithium sulfide, which involves an organic solvent in the preparation method. The high temperature and high pressure in the reaction container can cause the raw materials to melt, and the reaction between the two melts is not sufficient. Moreover, the operation process is complex, and the utilization rate of the raw materials is not high. Chinese patent CN115231527A discloses a method for preparing lithium sulfide by reducing lithium sulfate with an organic gas, and the raw material is lithium sulfate. The preparation process has the technical defects of high reaction temperature, complex process, high operation difficulty, high heat consumption, and the need for complex equipment and special conditions. SUMMARY

[0010] The technical problem to be solved by the present application is that in the current preparation method of lithium sulfide powder, the direct synthesis method produces lithium sulfide particles with large particle size after reaction, the electrochemical performance and cycle life of the particles are poor, and the preparation process needs the participation of organic solvents, the prepared lithium sulfide has many impurities and low raw material utilization; the solvent method has technical defects of long reaction time, high reaction temperature, fast consumption of starting materials, and serious product pollution; the high-temperature and high-pressure method has technical defects of partial evaporation of some raw materials during the preparation process, which is difficult to react with other raw materials, insufficient reaction, many impurities, low raw material utilization, high operation difficulty, high heat consumption, and the need for complex equipment and special conditions.

[0011] To solve the above technical problems, the technical solutions provided by the present application are as follows:

[0012] A method for producing lithium sulfide powder by direct combination of vapor, the method for producing lithium sulfide powder by direct combination of vapor is to heat metal lithium and sulfur or sulfur-containing substances to form vapor under the protection of inert gas, and then directly combine lithium vapor and sulfur vapor to produce lithium sulfide powder; the specific steps are as follows:

[0013] S1, heat metal lithium and sulfur or sulfur-containing substances in a lithium melting tank and a sulfur melting tank to form lithium vapor and sulfur vapor, respectively;

[0014] S2, the lithium vapor and sulfur vapor of S1 are introduced into a synthesis pipe in a lithium sulfide synthesis system through respective delivery pipes to directly combine to produce lithium sulfide powder, and unreacted sulfur vapor or lithium vapor is also obtained;

[0015] S3, the lithium sulfide powder and unreacted sulfur vapor or lithium vapor of S2 are blown into a first dust collector and a second dust collector by a circulating fan in the lithium sulfide synthesis system, and after being treated by the first dust collector and the second dust collector, double-dust-collected lithium sulfide powder and secondary dust collection tail gas are obtained;

[0016] S4, the secondary dust collection tail gas of S3 is returned to the delivery pipe of lithium vapor and is circulated and used inside the synthesis system by the circulating fan;

[0017] S5, the double-dust-collected lithium sulfide powder of S3 is further treated by vacuum heating to remove residual trace elemental sulfur, and the final product lithium sulfide powder is obtained.

[0018] Preferably, before the metal lithium, sulfur or sulfur-containing substances are heated to lithium vapor and sulfur vapor in S1, the metal lithium, sulfur or sulfur-containing substances need to be proportioned and weighed, and then the combined production system is extracted, vacuumized, cleaned, pressurized, the circulating fan is started, the impurities are removed, and the gas is pressurized.

[0019] Preferably, in S1, lithium metal and elemental sulfur or sulfur-containing substances are weighed according to the molar ratio of elemental lithium to elemental sulfur as (1.9-2) / 1, and are respectively placed into the trays of the molten lithium tank and the molten sulfur tank;

[0020] The combined production system is connected to the molten lithium tank, the molten sulfur tank, and the lithium sulfide synthesis system, and the lithium sulfide storage tank is respectively connected to the first dust collector and the second dust collector, and the valve connected to the lithium sulfide storage tank is opened.

[0021] Vacuumizing is to open the vacuum pump, vacuumize, and keep the pressure of the production system not higher than 0.1 Pa, open the heating power of the molten lithium tank, the molten sulfur tank, and the synthesis system, and set the temperature to 50-100℃;

[0022] When the temperature of the production system is 50-100℃ and the pressure of the system is not higher than 0.1 Pa, the gas inlet valve is closed and the gas outlet valve is opened, so that the pressure of the system is 0.11-0.15 MPa, and is kept for 2-5 min; then vacuumize to a pressure not higher than 0.1 Pa and keep for 2-5 min; repeat the operation for 2-3 times, which completes the atmosphere cleaning;

[0023] After the atmosphere cleaning of the system is completed, the temperature of the production system is controlled to 50-100℃ and the pressure is not higher than 0.1 Pa, and the temperature is ready to be raised;

[0024] Opening the circulating fan is to open the circulating fan cooling water inlet and outlet valves, and water is circulated to cool the driving part of the fan; the magnetic drive circulating fan is started, and the magnetic drive speed is set to 100-1200 r / min;

[0025] Melting and impurity removal is to set the temperature rising rate to 5-10℃ / min, the temperature of the molten lithium tank to 200-300℃, the temperature of the molten sulfur tank to 120-200℃, and the temperature of the synthesis system to 200-300℃, and keep the pressure of the production system not higher than 0.1 Pa, to further remove impurities carried by the raw materials, and the removal time is 10-30 min;

[0026] After the melting and impurity removal is completed, the gas inlet valve is closed, argon is filled, and the pressure of the production system is kept at -0.08-0.01 MPa.

[0027] Preferably, in S1, the temperature at which the molten lithium forms lithium vapor is 300-1350℃, and the temperature at which the molten sulfur forms sulfur vapor is 120-600℃.

[0028] Preferably, in S1, the purity of lithium metal is battery grade or industrial grade, and the purity of sulfur is not less than 99.0%, and the sulfur-containing substances include pyrite, chalcopyrite, sphalerite, lead sulfide, and sodium sulfide.

[0029] Preferably, the relative pressure control range of the synthesis tube in S2 is -0.1-0.05 MPa, the synthesis system temperature is 200-600 ℃, and the synthesis lithium sulfide time is 20-80 h.

[0030] Preferably, the lithium sulfide synthesis system in S2 includes a lithium vapor delivery pipe, a sulfur vapor delivery pipe, a lithium sulfide synthesis pipe, a circulating fan, a first dust collector and an air outlet pipe, a second dust collector and an air outlet pipe; the lithium sulfide synthesis system, except the circulating fan, is wrapped with a stainless steel sheath series mineral insulation heating cable for heating and is insulated with insulation materials, and the insulation temperature is 200-600 ℃.

[0031] Preferably, the temperature for removing residual trace sulfur in the vacuum heating treatment in S5 is 150-500 ℃, the pressure is <1 Pa, and the time is 1-5 h.

[0032] Preferably, the materials of the molten lithium tank, the molten sulfur tank, the delivery pipe, the tray, the synthesis pipe, the circulating fan blade and shaft, the first dust collector, the second dust collector and the pipeline contain nickel-chromium heat-resistant steel, and the content of the alloy element Cr in the nickel-chromium heat-resistant steel is not less than 17%, and the content of Ni is not less than 8%.

[0033] A device structure for producing lithium sulfide powder by direct combination of vapors includes a molten lithium tank, a molten sulfur tank and a synthesis system, and the molten lithium tank and the molten sulfur tank are connected to the synthesis system through a lithium vapor delivery pipe and a sulfur vapor delivery pipe respectively; wherein:

[0034] The molten lithium tank includes a molten lithium tank body, and a molten lithium tank cover is covered on the molten lithium tank body, and an air extraction hole, a first pressure gauge hole, a lithium vapor outlet and a first temperature measuring hole are arranged on the molten lithium tank cover, a first tray holder is arranged in the molten lithium tank body, the first tray holder is arranged on a first tray holder column, and a liquid lithium tray is arranged on the first tray holder;

[0035] The molten sulfur tank includes a molten sulfur tank body, and a molten sulfur tank cover is covered on the molten sulfur tank body, and an air inlet hole, a second pressure gauge hole, a sulfur vapor outlet and a second temperature measuring hole are arranged on the molten sulfur tank cover, a second tray holder is arranged in the molten sulfur tank body, the second tray holder is arranged on a second tray holder column, and a liquid sulfur tray is arranged on the second tray holder;

[0036] The synthesis system includes a magnetic drive circulating fan and a synthesis pipe, a circulating fan cooling water inlet and outlet are arranged on the outside of the magnetic drive circulating fan, a fan blade is arranged at the inside end of the synthesis pipe, the magnetic drive circulating fan is arranged on one side of the synthesis pipe, a first dust collector is connected to the other side of the synthesis pipe, a first lithium sulfide storage tank is connected to the lower end of the first dust collector, an air outlet pipe of the first dust collector is connected to the upper end of the first dust collector, a second dust collector is connected to the air outlet pipe of the first dust collector, the upper end of the second dust collector is communicated with the lithium vapor delivery pipe through a second dust collector air outlet pipe, and a second lithium sulfide storage tank is connected to the lower end of the second dust collector;

[0037] And the temperature measuring tube is arranged on the side wall of the synthetic tube close to the first dust collector, a first valve is arranged between the lower end of the first dust collector and the first lithium sulfide storage tank, and a second valve is arranged between the lower end of the second dust collector and the second lithium sulfide storage tank.

[0038] Preferably, the particle size of the final product lithium sulfide powder in S5 is 0.001-0.038mm, the purity is 98.00-99.999%, the utilization rate of lithium in lithium metal is 98-99.95%, and the utilization rate of sulfur in sulfur or sulfur-containing substances is 95-99.95%.

[0039] The technical principle of the application is as follows:

[0040] At high temperature, lithium vapor and sulfur vapor meet in the synthetic tube and directly combine to form lithium sulfide powder. Under the action of the magnetic drive circulating fan, the generated lithium sulfide powder, unreacted sulfur vapor or lithium vapor enters the primary dust collector and the secondary dust collector. Since lithium sulfide has a high melting point of 938℃ and a large crystal density of 1.66g / Cm 3 ; the lithium sulfide powder is separated by the cyclone dust collector and enters the lithium sulfide storage tank. The extremely fine lithium sulfide powder that is not collected, unreacted sulfur vapor or lithium vapor passes through the secondary dust collector outlet pipe into the lithium vapor delivery pipe and, under the action of the magnetic drive circulating fan, enters the synthesis system again, which is conducive to the full synthesis reaction.

[0041] In order to ensure that the entire system has good sealing performance, the application adopts magnetic drive.

[0042] The installation mode of the circulating fan with magnetic drive is horizontal or vertical installation. The unreacted sulfur vapor or lithium vapor passes through the air outlet pipes of the first dust collector and the second dust collector into the lithium vapor delivery pipe and, under the action of the circulating fan with magnetic drive, enters the synthesis system again, and the synthesized lithium sulfide powder is collected twice, which is conducive to controlling the particle size of the powder and making the particle size uniform.

[0043] The speed of the magnetic drive of the circulating fan is adjusted by frequency conversion. The application controls the gas flow rate in the synthesis system by adjusting the speed, and thus controls the particle size of the lithium sulfide powder collected in the first dust collector and the second dust collector. That is, the particle size of the synthesized lithium sulfide powder can be controlled by adjusting the flow rate, so that the particle size of the lithium sulfide powder does not change much, thereby obtaining lithium sulfide powder with controllable particle size and uniform particle size.

[0044] The blades of the circulating fan are located between the first dust collector and the position where lithium vapor and sulfur vapor enter the synthetic tube, which has the functions of stirring and accelerating the gas flow rate in the synthesis system. At the same time, the pressure in the molten sulfur tank, the molten lithium tank, the sulfur vapor delivery pipe and the lithium vapor delivery pipe is lower than that in the synthesis system, which is conducive to the evaporation of sulfur or lithium and the smooth progress of the subsequent vapor chemical synthesis.

[0045] Elemental sulfur melting point 112.8℃, boiling point 444.6℃, room temperature density 2.36g / cm 3 Sulfur is heated to form sulfur vapor, which exists in the form of S2, S3, S4, S5, S6, S8 and other structures. With the increase of temperature, S2 and S3 gradually increase, but they are still a mixture of multiple structures, and S2 will account for more than 99% only above 700℃. In the present application, S2 is mainly reacted with lithium vapor, and under the reaction temperature and pressure, S2, S3, S4, S5, S6, S8 and other components account for a certain percentage. When S2 is consumed by reaction, S3, S4, S5, S6, S8 and other components will decompose to generate S2. Therefore, in the synthesis system, S2 is continuously consumed and generated, so that the synthesis reaction continuously proceeds. Since the boiling point of sulfur is 444.6℃, the temperature of the molten sulfur tank in the present application is preferably 120-450℃.

[0046] In the present application, the molar ratio of elemental lithium to elemental sulfur is (1.9-2) / 1, and the excess of elemental sulfur is 0-0.1. Since the melting point and boiling point of elemental sulfur are low, the temperature is lower than 450℃, and the content of sulfur vapor in the production system is high, which is beneficial to purify the atmosphere of the production system. The excess of sulfur element is beneficial to the complete consumption of lithium element by reaction, but there will be residual sulfur. Therefore, the lithium sulfide powder needs to be vacuum heated to remove the residual trace amount of sulfur, thereby improving the purity of the prepared lithium sulfide powder.

[0047] In the present application, sulfur, sulfur-containing minerals or compounds can be used for heating and decomposition to provide sulfur vapor, including but not limited to pyrite, chalcopyrite, sphalerite, lead sulfide, sodium sulfide, etc.; the present application preferably uses elemental sulfur, and the vapor directly combines more conveniently.

[0048] In the present application, in order to increase the evaporation area, multi-layer trays are used in the molten sulfur tank and the molten lithium tank; the evaporation area of a single tray is 4200cm 2 The total evaporation area of 4 layers of trays is 16800cm 2 ; especially considering that the density of molten lithium is small, the effective volume of each tray is not more than 50% of the volume of the tray.

[0049] Metallic lithium melting point 180.5℃, boiling point 1342℃, room temperature density 0.534g / cm 3 According to the data, at 500℃, the vacuum evaporation rate of metallic lithium per minute is 1.219x10 -3 g / cm 2 , so the evaporation amount of lithium in the molten lithium tank per minute is 20.5g, and the evaporation amount of lithium per hour is 1230g. The evaporation rate of metallic lithium is related to pressure, temperature, surface area, etc. In production, the evaporation rate of metallic lithium is smaller than that in vacuum, and in order to improve the reaction speed, the evaporation temperature of metallic lithium needs to be appropriately increased. Therefore, the temperature of the molten lithium tank in the present application is preferably 600-900℃.

[0050] In the synthesis system, the vapor chemical reaction 4Li+S2=2Li2S occurs and releases a large amount of heat, so that the temperature of the reaction system is increased; and the temperature increase is not only beneficial to the decomposition of S3, S4, S5, S6, S8 and the like to generate S2, but also beneficial to the generation of lithium sulfide.

[0051] Compared with the prior art, the technical scheme has at least the following beneficial effects:

[0052] The scheme provides a method for producing lithium sulfide powder by directly combining vapors, solves the technical defects caused by the participation of flammable and explosive organic solvents which are not conducive to environmental protection and safe operation in the preparation process of lithium sulfide powder in the prior art, and also solves the technical defects of the prepared lithium sulfide, such as many impurities, low raw material utilization rate, high cost, high heat consumption, and complex equipment.

[0053] The lithium sulfide powder obtained by the combination reaction of lithium vapor and sulfur vapor and the unreacted sulfur vapor or lithium vapor are subjected to twice dust collection treatment, and then the circulation fan with magnetic transmission is used, which is not only beneficial to controlling the particle size of the powder to make the particle size of the obtained powder more uniform, but also can improve the utilization rate of raw materials.

[0054] The circulation fan of the present application adopts magnetic transmission, and the speed of the magnetic transmission is adjusted by frequency conversion. The present application can control the gas flow rate in the synthesis system by adjusting the speed, and then control the particle size of the lithium sulfide powder collected in the first dust collector and the second dust collector, so as to obtain lithium sulfide powder with controllable particle size and uniform particle size.

[0055] The installation mode of the circulation fan with magnetic transmission is horizontal or vertical installation, and the blades of the circulation fan are located between the first dust collector and the position where lithium vapor and sulfur vapor enter the synthesis pipe. The setting of the circulation fan, the first dust collector and the second dust collector can reduce the air pressure, so that the vapor chemical reaction can be quickly carried out.

[0056] The sulfur vapor formed by heating the raw material sulfur contains S2, S3, S4, S5, S6, S8 and the like, and the main structure reacting with lithium vapor is S2 structure. Other structures will also decompose to generate S2. The reaction efficiency of the vapor chemical reaction is higher than that of the traditional direct synthesis method, ball milling method, solvent method and high temperature and high pressure method, and the utilization rate is better.

[0057] The reaction ratio of lithium vapor and sulfur vapor in the present application is selected to be excessive sulfur vapor, which is not only easy to control the reaction process, but also beneficial to the control of the atmosphere in the chemical synthesis reaction process. Since the boiling point of metallic lithium is much higher than that of sulfur, if the metallic lithium is excessive, not only the production cost is increased, but also the cost of removing the residual lithium is higher than that of removing the residual sulfur, which is not conducive to large-scale industrial production.

[0058] The device structure for receiving metal lithium powder and sulfur powder in the molten sulfur tank and the molten lithium tank of the application adopts a plurality of layers of trays, which can not only increase the evaporation area of the raw material powder, but also reduce the influence of the density change of the molten metal sulfur on the subsequent chemical synthesis reaction of lithium vapor and sulfur vapor, and the reaction speed is improved by appropriately increasing the evaporation temperature of the metal lithium, thereby improving the utilization rate of the raw material and the reaction rate.

[0059] In summary, compared with other conventional methods, the method of the application can prepare lithium sulfide powder by chemical synthesis reaction of lithium vapor and excess sulfur vapor, the residual sulfur vapor or lithium vapor can be recycled and utilized, the residual sulfur of the lithium sulfide powder is removed by heating, and the lithium sulfide is subjected to secondary dust collection treatment. The method has the advantages of simple process, uniform particle size of the prepared lithium sulfide powder, controllable particle size, safety and environmental protection in the preparation process, wide application range, and is beneficial to industrial production practice and popularization. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0061] Figure 1 It is a device structure schematic diagram for directly combining vapor to produce lithium sulfide powder according to the application;

[0062] Figure 2 It is a tray rack schematic diagram in the device structure for directly combining vapor to produce lithium sulfide powder according to the application;

[0063] The signs in the drawings are explained as follows:

[0064] 1, suction hole, 2, first pressure gauge hole, 3, lithium vapor outlet, 4, first temperature measuring hole, 5, liquid lithium tray, 6, first tray rack, 7, first tray rack column, 8, molten lithium tank cover, 9, molten lithium tank body, 10, molten sulfur tank cover, 11, molten sulfur tank body, 12, air inlet hole, 13, second pressure gauge hole, 14, sulfur vapor outlet, 15, second temperature measuring hole, 16, liquid sulfur tray, 17, second tray rack, 18, second tray rack column, 19, sulfur vapor conveying pipe, 20, second temperature measuring pipe, 21, magnetic drive circulating fan, 22, circulating fan cooling water inlet and outlet, 23, fan blade, 24, synthesis pipe, 25, first dust collector, 26, first valve, 27, first lithium sulfide storage tank, 28, first dust collector air outlet pipe, 29, second dust collector, 30, second valve, 31, second lithium sulfide storage tank, 32, second dust collector air outlet pipe, 33, lithium vapor conveying pipe. DETAILED DESCRIPTION

[0065] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort belong to the scope of protection of the present application.

[0066] A method for producing lithium sulfide powder by direct combination of vapor, which comprises the following steps:

[0067] S1, heating metal lithium and sulfur or sulfur-containing substances in a lithium melting tank and a sulfur melting tank respectively to form lithium vapor and sulfur vapor;

[0068] S2, introducing the lithium vapor and the sulfur vapor of S1 into a synthesis pipe in a lithium sulfide synthesis system through respective delivery pipes to directly combine to generate lithium sulfide powder, and also obtaining unreacted sulfur vapor or lithium vapor;

[0069] S3, blowing the lithium sulfide powder and the unreacted sulfur vapor or lithium vapor of S2 into a first dust collector and a second dust collector in the lithium sulfide synthesis system by a circulating fan, and obtaining double-dust-collection-treated lithium sulfide powder and secondary dust collection tail gas by processing through the first dust collector and the second dust collector;

[0070] S4, returning the secondary dust collection tail gas of S3 into the delivery pipe of the lithium vapor, and recycling the lithium vapor in the synthesis system by the circulating fan;

[0071] S5, further vacuum heating the double-dust-collection-treated lithium sulfide powder of S3 to remove residual trace elemental sulfur, and obtaining the final product lithium sulfide powder.

[0072] In particular, before the heating of the metal lithium, sulfur or sulfur-containing substances in S1 is converted into lithium vapor and sulfur vapor, the metal lithium, sulfur or sulfur-containing substances need to be proportioned and weighed, and then the combined production system is connected, vacuumized, cleaned, pressurized, the circulating fan is opened, and the impurities are removed by melting.

[0073] In particular, the proportioning and weighing in S1 is to weigh the metal lithium and elemental sulfur or sulfur-containing substances according to a molar ratio of elemental lithium to elemental sulfur of (1.9-2) / 1, and respectively put them into the trays of the lithium melting tank and the sulfur melting tank.

[0074] The combined production system is to connect the lithium melting tank, the sulfur melting tank and the lithium sulfide synthesis system, connect the lithium sulfide storage tank with the first dust collector and the second dust collector respectively, and open the valve connected with the lithium sulfide storage tank.

[0075] Vacuumizing is to open the vacuum pump, vacuumize and keep the production system pressure not higher than 0.1 Pa, open the lithium melting tank, sulfur melting tank and synthetic system heating power, set the temperature to 50-100℃;

[0076] Cleaning atmosphere is to close the vacuum valve, open the gas filling valve when the production system temperature is 50-100℃ and the system pressure is not higher than 0.1 Pa, so that the system pressure is 0.11-0.15 MPa, keep for 2-5 min; then vacuumize to the pressure not higher than 0.1 Pa and keep for 2-5 min; repeat the operation for 2-3 times, which is to complete the atmosphere cleaning;

[0077] Pressure keeping is to control the production system temperature to 50-100℃ and the pressure not higher than 0.1 Pa after the atmosphere cleaning, and prepare for temperature rising;

[0078] Starting the circulating fan is to open the circulating fan cooling water inlet and outlet valve, and water cooling fan transmission part; start the magnetic drive circulating fan, set the magnetic drive rotating speed to 100-1200 r / min;

[0079] Melting and impurity removal is to set the temperature rising rate to 5-10℃ / min, the lithium melting tank temperature to 200-300℃, the sulfur melting tank temperature to 120-200℃, the synthetic system temperature to 200-300℃, and keep the production system pressure not higher than 0.1 Pa, to further remove the impurities carried by the raw materials, and the removal time is 10-30 min;

[0080] Gas filling and pressure keeping is to close the vacuum valve after the melting and impurity removal is completed, fill in argon and keep the production system pressure to -0.08-0.01 MPa.

[0081] In particular, the temperature of the molten lithium in the lithium melting tank in S1 to form lithium vapor is 300-1350℃, and the temperature of the molten sulfur in the sulfur melting tank to form sulfur vapor is 120-600℃.

[0082] In particular, the purity of the lithium in S1 is battery grade or industrial grade, and the purity of sulfur is not less than 99.0%, and the sulfur-containing substances include pyrite, chalcopyrite, sphalerite, lead sulfide and sodium sulfide.

[0083] In particular, the relative pressure control range of the synthesis tube to directly combine to form lithium sulfide powder in S2 is -0.1-0.05 MPa, the synthesis system temperature is 200-600℃, and the synthesis lithium sulfide time is 20-80 h.

[0084] In particular, the lithium sulfide synthesis system in S2 comprises a lithium vapor delivery pipe, a sulfur vapor delivery pipe, a lithium sulfide synthesis pipe, a circulating fan, a first dust collector and an air outlet pipe, and a second dust collector and an air outlet pipe. Except the circulating fan, the other parts of the lithium sulfide synthesis system are wrapped with a stainless steel sheath series mineral insulated heating cable and heated, and are insulated with insulation materials, with an insulation temperature of 200-600℃.

[0085] In particular, the temperature for removing the residual trace sulfur in the vacuum heating treatment in S5 is 150-500℃, the pressure is <1Pa, and the time is 1-5h.

[0086] In particular, the materials of the molten lithium tank, the molten sulfur tank, the delivery pipe, the tray, the synthesis pipe, the circulating fan blade and shaft, the first dust collector, the second dust collector and the pipeline comprise a nickel-chromium heat-resistant steel, and the content of the alloy element Cr in the nickel-chromium heat-resistant steel is not less than 17%, and the content of Ni is not less than 8%.

[0087] A device structure for producing lithium sulfide powder by direct combination of vapors comprises a molten lithium tank, a molten sulfur tank and a synthesis system, as shown in Figure 1 The molten lithium tank and the molten sulfur tank are connected to the synthesis system through a lithium vapor delivery pipe 33 and a sulfur vapor delivery pipe 19, respectively.

[0088] The molten lithium tank comprises a molten lithium tank body 9, and a molten lithium tank cover 8 is covered on the molten lithium tank body 9. The molten lithium tank cover 8 is provided with an air extraction hole 1, a first pressure gauge hole 2, a lithium vapor outlet 3 and a first temperature measuring hole 4. A first tray rack 6 is arranged in the molten lithium tank body 9, and the specific shape is shown in Figure 2 The tray rack 6 is arranged on a first tray rack stand 7, and the first tray rack 6 is provided with a liquid lithium tray 5.

[0089] The molten sulfur tank comprises a molten sulfur tank body 11, and a molten sulfur tank cover 10 is covered on the molten sulfur tank body 11. The molten sulfur tank cover 10 is provided with an air charging hole 12, a second pressure gauge hole 13, a sulfur vapor outlet 14 and a second temperature measuring hole 15. A second tray rack 17 is arranged in the molten sulfur tank body 11, and the second tray rack 17 is arranged on a second tray rack stand 18. The second tray rack 17 is provided with a liquid sulfur tray 16.

[0090] The synthesis system comprises a magnetic drive circulating fan 21 and a synthesis pipe 24, the outer side of the magnetic drive circulating fan 21 is provided with a circulating fan cooling water inlet and outlet 22, a fan blade 23 is arranged at the inner end of the synthesis pipe 24 in depth, the magnetic drive circulating fan 21 is arranged at one side of the synthesis pipe 24, the other side of the synthesis pipe 24 is connected with a first dust collector 25, the lower end of the first dust collector 25 is connected with a first lithium sulfide storage tank 27, the upper end of the first dust collector 25 is connected with a first dust collector air outlet pipe 28, the first dust collector air outlet pipe 28 is connected with a second dust collector 29, the upper end of the second dust collector 29 is communicated with a lithium vapor conveying pipe 33 through a second dust collector air outlet pipe 32, and the lower end of the second dust collector 29 is connected with a second lithium sulfide storage tank 31.

[0091] The temperature measuring pipe 20 is arranged on the side wall of the synthesis pipe 24 close to the first dust collector 25, the first valve 26 is arranged between the lower end of the first dust collector 25 and the first lithium sulfide storage tank 27, and the second valve 30 is arranged between the lower end of the second dust collector 29 and the second lithium sulfide storage tank 31.

[0092] In particular, the particle size of the final product lithium sulfide powder in S5 is 0.001-0.038mm, the purity is 98.00-99.999%, the utilization rate of lithium in metallic lithium is 98-99.95%, and the utilization rate of sulfur in sulfur or sulfur-containing substances is 95-99.95%.

[0093] Embodiment 1

[0094] A method for producing lithium sulfide powder by direct combination of vapor, the method comprising the following steps:

[0095] S1, proportioning and weighing: according to the element molar ratio Li / S = 1.9 / 1, 12.362kg of battery-grade metallic lithium containing elemental lithium is weighed and equally loaded into 4 trays arranged in the same axis and in sequence from top to bottom of a lithium melting tank, and 30kg of 99.5% purity sulfur containing elemental sulfur is weighed and equally loaded into 4 trays arranged in the same axis and in sequence from top to bottom of a sulfur melting tank;

[0096] S2, combining a production system: connecting the lithium melting tank, the sulfur melting tank and the lithium sulfide synthesis system, connecting the lithium sulfide storage tank with the first dust collector and the second dust collector respectively, and opening the valve connected with the lithium sulfide storage tank

[0097] S3, vacuumizing: opening the vacuum pump, vacuumizing and keeping the pressure of the production system not higher than 0.1Pa, opening the heating power supply of the lithium melting tank, the sulfur melting tank and the synthesis system, and setting the temperature to 100℃;

[0098] S4, cleaning atmosphere: when the production system temperature is 100°C, the system pressure is not higher than 0.1 Pa, the exhaust valve is closed, the gas filling valve is opened, high-purity argon is filled into the production system until the system pressure is 0.15 MPa, and the system is kept for 2 min; then vacuum is extracted until the pressure is not higher than 0.1 Pa and kept for 2 min; such operation is repeated for 2-3 times, and the atmosphere cleaning is completed;

[0099] S5, pressure maintaining: after the system atmosphere cleaning is completed, the production system temperature is controlled to be 100°C, and the pressure is not higher than 0.1 Pa, and the temperature is ready to be raised;

[0100] S6, starting the circulating fan: the circulating fan cooling water inlet and outlet valves are opened, the circulating fan driving part is water-cooled, the magnetic driving circulating fan is started, and the magnetic driving rotating speed is set to be 600 r / min;

[0101] S7, melting and impurity removal: the temperature rising rate is set to be 5°C / min, the melting lithium tank temperature is 200°C, the melting sulfur tank temperature is 120°C, and the synthesis system temperature is 200°C, the production system pressure is kept to be not higher than 0.1 Pa, and the raw material attached impurities are further removed, and the removal time is 30 min;

[0102] S8, gas filling and pressure maintaining: after the melting and impurity removal is completed, the exhaust valve is closed, argon is filled, and the production system pressure is kept to be -0.08 MPa;

[0103] S9, temperature rising and combination: after the gas filling and pressure maintaining, the temperature continues to be raised. The synthesis system temperature is set to be 300°C, the melting sulfur tank temperature is 300°C, and the melting lithium tank temperature is 600°C; the lithium vapor and the sulfur vapor are combined into lithium sulfide powder in the synthesis system, and the synthesis time is 36 h; during the temperature rising and combination, the production system pressure is kept to be -0.08 MPa;

[0104] S10, vacuum desulfurization: under the conditions of the pressure being not higher than 1 Pa and the temperature being 240°C, the residual trace amount of sulfur is removed to obtain the product lithium sulfide powder after keeping for 4 h.

[0105] In the S5 of the embodiment, the particle size of the final product lithium sulfide powder is 0.012 mm, the purity is 99.5%, the utilization rate of lithium in the metallic lithium is 99.91%, and the utilization rate of sulfur in the sulfur or sulfur-containing substance is 95.6%.

[0106] Example 2

[0107] A method for producing lithium sulfide powder by direct combination of vapors, wherein the method comprises the following steps: heating metallic lithium and sulfur or a sulfur-containing substance to form vapors under the protection of inert gas, and directly combining the lithium vapor and the sulfur vapor to generate lithium sulfide powder.

[0108] S1, proportioning and weighing: according to the element molar ratio Li / S = 2.0 / 1, 17.35 kg of battery-grade lithium metal containing elemental lithium is weighed and equally loaded into the four trays arranged in the same axis and sequentially from top to bottom in the lithium melting tank; 40 kg of 99.5% pure sulfur containing elemental sulfur is weighed and equally loaded into the four trays arranged in the same axis and sequentially from top to bottom in the sulfur melting tank;

[0109] S2, combined production system: connecting the lithium melting tank, the sulfur melting tank and the lithium sulfide synthesis system, connecting the lithium sulfide storage tank with the first dust collector and the second dust collector respectively, opening the valve connected with the lithium sulfide storage tank

[0110] S3, vacuumizing: opening the vacuum pump, vacuumizing and keeping the pressure of the production system not higher than 0.1 Pa, opening the heating power of the lithium melting tank, the sulfur melting tank and the synthesis system, setting the temperature to 50℃;

[0111] S4, cleaning atmosphere: when the temperature of the production system is 50℃ and the pressure of the system is not higher than 0.1 Pa, closing the air exhaust valve, opening the air charging valve to charge high-purity argon into the production system until the pressure of the system is 0.11 MPa, keeping for 5 min; vacuumizing again until the pressure is not higher than 0.1 Pa and keeping for 4 min; repeating the operation for 2-3 times, which completes the atmosphere cleaning;

[0112] S5, pressure maintaining: after the atmosphere cleaning of the system is completed, controlling the temperature of the production system to 50℃ and the pressure not higher than 0.1 Pa, preparing for temperature rising;

[0113] S6, starting the circulating fan: opening the circulating fan water inlet and outlet valve, water cooling the fan transmission part; starting the magnetic drive circulating fan, setting the magnetic drive rotating speed to 300 r / min;

[0114] S7, melting and impurity removal: setting the temperature rising rate to 10℃ / min, the temperature of the lithium melting tank to 300℃, the temperature of the sulfur melting tank to 200℃, the temperature of the synthesis system to 300℃, keeping the pressure of the production system not higher than 0.01 Pa, further removing the impurities carried by the raw materials, and the removal time is 10 min;

[0115] S8, gas charging and pressure maintaining: after the melting and impurity removal is completed, closing the air exhaust valve, charging argon and keeping the pressure of the production system to 0.01 MPa;

[0116] S9, temperature rising and combination: after the gas charging and pressure maintaining, continuing to rise the temperature. Setting the temperature of the synthesis system to 450℃, the temperature of the sulfur melting tank to 320℃, and the temperature of the lithium melting tank to 1000℃; making the lithium vapor and the sulfur vapor combine into lithium sulfide powder in the synthesis system, and the synthesis time is 60 h; during the temperature rising and combination, keeping the pressure of the production system to 0.01 MPa;

[0117] S10, vacuum desulfurization: keeping the temperature at 500℃ for 1 h under the condition of pressure not higher than 1 Pa, and removing the residual trace amount of sulfur to obtain the product lithium sulfide powder.

[0118] The particle size of the final product lithium sulfide powder in this embodiment S5 is 0.004 mm, the purity is 99.996%, the utilization rate of lithium in metallic lithium is 98.5%, and the utilization rate of sulfur in sulfur or sulfur-containing substances is 99.8%.

[0119] Embodiment 3

[0120] A method for producing lithium sulfide powder by direct combination of vapor, which comprises heating metallic lithium and sulfur or sulfur-containing substances to form vapor under the protection of inert gas, and directly combining lithium vapor and sulfur vapor to produce lithium sulfide powder; the specific steps are as follows:

[0121] S1, proportioning and weighing: according to the elemental molar ratio Li / S = 1.92 / 1, 20.82 kg of battery-grade metallic lithium containing elemental lithium is weighed and equally loaded into the four trays arranged in the same axis and in sequence from top to bottom of the lithium melting tank; 50 kg of 99.5% pure sulfur is weighed and equally loaded into the four trays arranged in the same axis and in sequence from top to bottom of the sulfur melting tank;

[0122] S2, combining the production system: connecting the lithium melting tank, the sulfur melting tank and the lithium sulfide synthesis system, connecting the lithium sulfide storage tank with the first and second dust collectors respectively, and opening the valve connected with the lithium sulfide storage tank

[0123] S3, vacuumizing: opening the vacuum pump, vacuumizing and keeping the pressure of the production system not higher than 0.1 Pa, opening the heating power of the lithium melting tank, the sulfur melting tank and the synthesis system, and setting the temperature to 80℃;

[0124] S4, cleaning the atmosphere: when the temperature of the production system is 80℃ and the pressure of the system is not higher than 0.1 Pa, closing the air inlet valve, opening the air inlet valve to fill high-purity argon into the production system to a pressure of 0.13 MPa, and keeping for 3 min; then vacuumizing to a pressure not higher than 0.1 Pa and keeping for 3 min; repeating the operation for 2-3 times, which completes the atmosphere cleaning;

[0125] S5, pressure maintaining: after the atmosphere cleaning of the system is completed, the temperature of the production system is controlled to 80℃ and the pressure is not higher than 0.1 Pa, and the temperature is ready to be raised;

[0126] S6, starting the circulating fan: opening the circulating fan water inlet and outlet valves, and circulating water to cool the driving part of the fan; starting the magnetic driving circulating fan and setting the magnetic driving speed to 900 r / min;

[0127] S7, melting and impurity removal: setting the temperature rising rate to 8℃ / min, the temperature of the lithium melting tank to 240℃, the temperature of the sulfur melting tank to 150℃, and the temperature of the synthesis system to 220℃, keeping the pressure of the production system not higher than 0.1 Pa, and further removing the impurities carried by the raw materials, and the removal time is 20 min;

[0128] S8, gas charging and pressure maintaining: after the impurity removal is completed, the air extraction valve is closed, argon is charged, and the production system pressure is maintained at -0.06 MPa;

[0129] S9, temperature rising and combination: after the gas charging and pressure maintaining, the temperature rising is continued. The synthesis system temperature is set to 380℃, the molten sulfur tank temperature is 360℃, and the molten lithium tank temperature is 750℃; the lithium vapor and the sulfur vapor are combined into lithium sulfide powder in the synthesis system, and the synthesis time is 55 h; during the temperature rising and combination, the production system pressure is maintained at -0.06 MPa;

[0130] S10, vacuum desulfurization: under the condition that the pressure is not higher than 1 Pa and the temperature is 200℃, the residual trace amount of sulfur is removed to obtain the product lithium sulfide powder after heat preservation for 5 h.

[0131] The particle size of the final product lithium sulfide powder in the embodiment S5 is 0.036 mm, the purity is 99.92%, the utilization rate of lithium in the metallic lithium is 99.92%, and the utilization rate of sulfur in the sulfur or sulfur-containing substance is 97.4%.

[0132] Example 4

[0133] A method for producing lithium sulfide powder by direct combination of vapor, which comprises heating metallic lithium and sulfur or sulfur-containing substance to form vapor under the protection of inert gas, and directly combining lithium vapor and sulfur vapor to generate lithium sulfide powder; the specific steps are as follows:

[0134] S1, proportioning and weighing: the ingredients are proportioned according to the element molar ratio Li / S = 1.98 / 1; 8.588 kg of battery-grade metallic lithium containing elemental lithium is weighed and equally loaded into the 4 trays arranged in the same axis and in sequence from top to bottom of the molten lithium tank; 20 kg of 99.5% purity sulfur containing elemental sulfur is weighed and equally loaded into the 4 trays arranged in the same axis and in sequence from top to bottom of the molten sulfur tank;

[0135] S2, combining the production system: the molten lithium tank, the molten sulfur tank, and the lithium sulfide synthesis system are connected, the lithium sulfide storage tank is connected with the first dust collector and the second dust collector respectively, and the valve connected with the lithium sulfide storage tank is opened

[0136] S3, vacuum extraction: the vacuum pump is opened, the vacuum extraction is performed, and the production system pressure is maintained at not higher than 0.1 Pa; the heating power of the molten lithium tank, the molten sulfur tank, and the synthesis system is turned on, and the temperature is set to 60℃;

[0137] S4, atmosphere cleaning: when the production system temperature is 60℃ and the system pressure is not higher than 0.1 Pa, the air extraction valve is closed, the gas charging valve is opened, high-purity argon is charged into the production system until the system pressure is 0.13 MPa, and the atmosphere cleaning is maintained for 3 min; then the vacuum extraction is performed again until the pressure is not higher than 0.1 Pa and maintained for 5 min; the above operation is repeated for 2-3 times, and the atmosphere cleaning is completed.

[0138] S5, pressure maintaining: after the system atmosphere is cleaned, the temperature of the production system is controlled at 60°C, and the pressure is not higher than 0.1 Pa, in preparation for temperature rising;

[0139] S6, starting the circulating fan: the water inlet and outlet valves of the circulating fan are opened, the circulating fan drive part is cooled by water, and the magnetic drive circulating fan is started, with the magnetic drive rotating speed set at 800 r / min;

[0140] S7, melting and impurity removal: the temperature rising rate is set at 6°C / min, the temperature of the lithium melting tank is 280°C, the temperature of the sulfur melting tank is 140°C, and the temperature of the synthesis system is 260°C, and the pressure of the production system is maintained at not higher than 0.1 Pa, to further remove impurities carried by the raw materials, with the removal time being 25 min;

[0141] S8, gas filling and pressure maintaining: after the melting and impurity removal is completed, the exhaust valve is closed, argon is filled, and the pressure of the production system is maintained at -0.04 MPa;

[0142] S9, temperature rising and combination: after the gas filling and pressure maintaining, the temperature rising is continued. The temperature of the synthesis system is set at 240°C, the temperature of the sulfur melting tank is 280°C, and the temperature of the lithium melting tank is 900°C. Lithium vapor and sulfur vapor are combined into lithium sulfide powder in the synthesis system, with the synthesis time being 30 h. During the temperature rising and combination, the pressure of the production system is maintained at -0.04 MPa.

[0143] S10, vacuum desulfurization: under the conditions of a pressure not higher than 1 Pa and a temperature of 360°C, the residual trace amount of sulfur is removed to obtain the product lithium sulfide powder, with the holding time being 3 h.

[0144] In the S5 of this embodiment, the particle size of the final product lithium sulfide powder is 0.008 mm, the purity is 99.21%, the utilization rate of lithium in the metallic lithium is 99.56%, and the utilization rate of sulfur in the sulfur or sulfur-containing substance is 96.8%.

[0145] Example 5

[0146] A method for producing lithium sulfide powder by direct combination of vapors, which comprises heating metallic lithium and sulfur or a sulfur-containing substance to form vapors under the protection of inert gas, and directly combining lithium vapor and sulfur vapor to generate lithium sulfide powder. The specific steps are as follows:

[0147] S1, proportioning and weighing: the raw materials are proportioned according to the element molar ratio Li / S = 1.95 / 1. 15.225 kg of battery-grade metallic lithium containing elemental lithium is weighed and equally loaded into the 4 trays arranged in the same axis and in sequence from top to bottom of the lithium melting tank. 36 kg of pyrite (chemical formula FeS2) containing elemental sulfur is weighed and equally loaded into the 4 trays arranged in the same axis and in sequence from top to bottom of the sulfur melting tank;

[0148] S2, combination production system: connecting the molten lithium tank, the molten sulfur tank and the lithium sulfide synthesis system, connecting the lithium sulfide storage tank with the first dust collector and the second dust collector, and opening the valve connected with the lithium sulfide storage tank

[0149] S3, vacuumizing: opening the vacuum pump, vacuumizing and keeping the pressure of the production system not higher than 0.1 Pa, opening the heating power of the molten lithium tank, the molten sulfur tank and the synthesis system, and setting the temperature to 100℃;

[0150] S4, cleaning atmosphere: when the temperature of the production system is 100℃ and the pressure of the system is not higher than 0.1 Pa, closing the air exhaust valve, opening the air filling valve to fill high-purity argon into the production system until the pressure of the system is 0.12 MPa, keeping for 5 min, vacuumizing again until the pressure is not higher than 0.1 Pa and keeping for 1 min, and repeating the operation for 2-3 times, which completes the atmosphere cleaning;

[0151] S5, pressure keeping: after the atmosphere cleaning of the system, controlling the temperature of the production system to 100℃ and the pressure not higher than 0.1 Pa, and preparing for temperature rising;

[0152] S6, starting the circulating fan: opening the circulating fan water inlet and outlet valve, water cooling the fan transmission part, starting the magnetic transmission circulating fan, and setting the magnetic transmission rotating speed to 450 r / min;

[0153] S7, melting and impurity removing: setting the temperature rising rate to 7℃ / min, the temperature of the molten lithium tank to 220℃, the temperature of the molten sulfur tank to 180℃, and the temperature of the synthesis system to 240℃, keeping the pressure of the production system not higher than 0.1 Pa, and further removing the impurities attached to the raw materials, and the removing time is 30 min;

[0154] S8, air filling and pressure keeping: after the melting and impurity removing, closing the air exhaust valve, filling argon and keeping the pressure of the production system to -0.07 MPa;

[0155] S9, temperature rising and combining: after the air filling and pressure keeping, continuing to rise the temperature, setting the temperature of the synthesis system to 280℃, the temperature of the molten sulfur tank to 500℃, and the temperature of the molten lithium tank to 800℃, combining lithium vapor and sulfur vapor into lithium sulfide powder in the synthesis system, and the synthesis time is 35 h, and keeping the pressure of the production system to -0.07 MPa during the temperature rising and combining;

[0156] S10, vacuum desulfurization: keeping the temperature at 420℃ for 2 h under the condition that the pressure is not higher than 1 Pa, and removing the residual trace sulfur to obtain the product lithium sulfide powder.

[0157] The particle size of the final product lithium sulfide powder in S5 of the embodiment is 0.025 mm, the purity is 98.53%, the utilization rate of lithium in metallic lithium is 99.05%, and the utilization rate of sulfur in sulfur or sulfur-containing substances is 97.51%.

[0158] The scheme provides a method for producing lithium sulfide powder by directly combining steam, solves the technical defects of the participation of flammable and explosive organic solvents in the preparation process of lithium sulfide powder in the prior art, and also solves the technical defects of many impurities in the prepared lithium sulfide, low raw material utilization rate, high cost, high heat consumption, complex equipment and the like.

[0159] The lithium sulfide powder obtained by combining lithium steam and sulfur steam and the unreacted sulfur steam or lithium steam are subjected to twice dust collection treatment, and then are subjected to the action of a circulating fan driven by magnetic force, so that the particle size of the powder can be controlled to make the particle size of the obtained powder more uniform, and the utilization rate of raw materials can be improved.

[0160] The circulating fan of the present application is driven by magnetic force, and the rotating speed of the magnetic drive is adjusted by frequency conversion. The present application can control the gas flow rate in the synthesis system by adjusting the rotating speed, and then control the particle size of the lithium sulfide powder collected in the first dust collector and the second dust collector, so that the lithium sulfide powder with controllable particle size and uniform particle size can be obtained.

[0161] The installation mode of the circulating fan driven by magnetic force is horizontal or vertical installation. The blades of the circulating fan are located between the first dust collector and the lithium steam and sulfur steam entering the synthesis pipe. The setting of the circulating fan, the first dust collector and the second dust collector can reduce the gas pressure, so that the chemical reaction of the steam can be quickly carried out.

[0162] The sulfur steam formed by heating the raw material sulfur contains S2, S3, S4, S5, S6 and S8 structures. The main structure reacting with lithium steam is S2 structure, and other structures will also decompose to form S2. The reaction efficiency of the steam chemical reaction is higher than that of the traditional direct synthesis method, ball milling method, solvent method and high temperature and high pressure method, and the utilization rate is better.

[0163] The reaction ratio of lithium steam and sulfur steam in the present application is selected to be excessive sulfur steam, which is easy to control the reaction process and is beneficial to the control of the atmosphere in the chemical synthesis reaction process. Since the boiling point of metallic lithium is much higher than that of sulfur, if the metallic lithium is excessive, the production cost is increased, and the cost of removing the residual lithium is also higher than that of removing the residual sulfur, which is not conducive to large-scale industrial production.

[0164] The device structure for receiving metallic lithium powder and sulfur powder in the molten sulfur tank and the molten lithium tank in the present application all adopts a multi-layer tray, which can not only increase the evaporation area of the raw material powder, but also reduce the influence of the density change of the molten metallic sulfur on the subsequent chemical synthesis reaction of lithium steam and sulfur steam. By appropriately increasing the evaporation temperature of the metallic lithium to improve the reaction speed, the utilization rate of raw materials and the reaction rate are improved.

[0165] In summary, compared with other conventional methods, the method of the present application prepares lithium sulfide powder by chemical synthesis reaction of lithium vapor and excess sulfur vapor, the residual sulfur vapor or lithium vapor can be recycled and utilized, the residual sulfur of the lithium sulfide powder is removed by heating, and the lithium sulfide is subjected to secondary dust collection treatment. The method has simple process, uniform particle size of the prepared lithium sulfide powder, controllable particle size, safety and environmental protection in the preparation process, wide application range, and is beneficial to industrial production practice and popularization.

[0166] The above describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A process for the production of lithium sulfide powder by vapor direct combination, characterized in that, The method for directly combining the vapor to produce lithium sulfide powder is to heat metal lithium and sulfur or sulfur-containing substances respectively to form vapor under inert gas protection, and directly combine lithium vapor and sulfur vapor to generate lithium sulfide powder; the specific steps are as follows: S1, heating metal lithium and sulfur or sulfur-containing substances respectively in a lithium melting tank and a sulfur melting tank to form lithium vapor and sulfur vapor; S2, the lithium vapor and the sulfur vapor in S1 are introduced into a synthesis pipe in a lithium sulfide synthesis system through respective delivery pipes to directly combine to generate lithium sulfide powder, and unreacted sulfur vapor or lithium vapor is also obtained; S3, the lithium sulfide powder, the unreacted sulfur vapor or lithium vapor in S2 are blown into a first dust collector and a second dust collector in the lithium sulfide synthesis system by a circulating fan, and after being treated by the first dust collector and the second dust collector, double-dust-collection-treated lithium sulfide powder and secondary dust collection tail gas are obtained; S4, the secondary dust collection tail gas in S3 is returned to the delivery pipe of the lithium vapor and is circulated in the synthesis system by the circulating fan; S5, the double-dust-collection-treated lithium sulfide powder in S3 is further subjected to vacuum heating treatment to remove residual trace elemental sulfur, and the final product lithium sulfide powder is obtained.

2. The method of claim 1, wherein the lithium sulfide powder is produced by vapor direct combination. Before the heating of the metal lithium, sulfur or sulfur-containing substances in S1 into lithium vapor and sulfur vapor, the metal lithium, sulfur or sulfur-containing substances need to be proportioned and weighed, and then the combined production system, vacuum pumping, atmosphere cleaning, pressure maintaining, opening of the circulating fan, melting and impurity removal, and gas charging and pressure maintaining are performed.

3. The method of claim 2, wherein the lithium sulfide powder is produced by vapor direct combination. The proportioning and weighing in S1 is to weigh the metal lithium and elemental sulfur or sulfur-containing substances according to the molar ratio of elemental lithium to elemental sulfur of (1.9-2) / 1, and respectively put them into the trays of the lithium melting tank and the sulfur melting tank; The combined production system is to connect the lithium melting tank, the sulfur melting tank and the lithium sulfide synthesis system, connect the lithium sulfide storage tank with the first dust collector and the second dust collector respectively, and open the valve connected with the lithium sulfide storage tank; The vacuum pumping is to open the vacuum pump, pump the vacuum and maintain the pressure of the production system not higher than 0.1 Pa, open the heating power of the lithium melting tank, the sulfur melting tank and the synthesis system, and set the temperature to 50-100℃; The atmosphere cleaning is to close the air exhaust valve and open the gas charging valve when the temperature of the production system is 50-100℃ and the pressure of the system is not higher than 0.1 Pa, so that the pressure of the system is 0.11-0.15 MPa and is maintained for 2-5 min; then the vacuum is pumped again to a pressure not higher than 0.1 Pa and is maintained for 2-5 min; such operation is repeated for 2-3 times, and the atmosphere cleaning is completed; The pressure maintaining is to control the temperature of the production system to 50-100℃ and the pressure not higher than 0.1 Pa after the completion of the atmosphere cleaning, and prepare for temperature rising; The opening of the circulating fan is to open the inlet and outlet valve of the circulating fan cooling water, water the fan transmission part, open the magnetic drive circulating fan, and set the magnetic drive rotating speed to 100-1200 r / min; The melting and impurity removal is to set the temperature rising rate to 5-10℃ / min, the temperature of the lithium melting tank to 200-300℃, the temperature of the sulfur melting tank to 120-200℃, the temperature of the synthesis system to 200-300℃, and maintain the pressure of the production system not higher than 0.1 Pa, to further remove the impurities attached to the raw materials, and the removal time is 10-30 min; After the impurities are removed by melting, the exhaust valve is closed, argon is filled, and the pressure of the production system is kept at -0.08-0.01 MPa.

4. The method of claim 1, wherein the lithium sulfide powder is produced by vapor direct combination. The temperature for forming lithium vapor in the molten lithium tank in S1 is 300-1350℃, and the temperature for forming sulfur vapor in the molten sulfur tank is 120-600℃.

5. The method of claim 1, wherein the lithium sulfide powder is produced by vapor direct combination. The purity of the lithium in S1 is battery grade or industrial grade, and the purity of the sulfur is not less than 99.0%, and the sulfur-containing substances include pyrite, chalcopyrite, sphalerite, lead sulfide, and sodium sulfide.

6. The method of claim 1, wherein the lithium sulfide powder is produced by vapor direct combination. The relative pressure control range for the synthesis tube in S2 is -0.1-0.05 MPa, the synthesis system temperature is 200-600℃, and the synthesis time of lithium sulfide is 20-80h.

7. The method of claim 1, wherein the lithium sulfide powder is produced by vapor direct combination. The lithium sulfide synthesis system in S2 includes a lithium vapor delivery tube, a sulfur vapor delivery tube, a lithium sulfide synthesis tube, a circulating fan, a first dust collector and an air outlet tube, and a second dust collector and an air outlet tube; all parts of the lithium sulfide synthesis system except the circulating fan are wrapped with a stainless steel sheathed series mineral insulated heating cable and heated, and are insulated with insulation materials, and the insulation temperature is 200-600℃.

8. The method of claim 1, wherein the lithium sulfide powder is produced by vapor direct combination. The temperature for removing residual trace sulfur by vacuum heating treatment in S5 is 150-500℃, the pressure is <1 Pa, and the time is 1-5h.

9. The method of claim 3, wherein the lithium sulfide powder is produced by vapor direct combination. The materials of the molten lithium tank, the molten sulfur tank, the delivery tube, the tray, the synthesis tube, the circulating fan blades and shaft, the first dust collector, the second dust collector, and the pipeline include nickel-chromium heat-resistant steel, and the content of the alloy element Cr in the nickel-chromium heat-resistant steel is not less than 17%, and the content of Ni is not less than 8%.

10. The method of claim 3, wherein the lithium sulfide powder is produced by vapor direct combination. The particle size of the final product lithium sulfide powder in S5 is 0.001-0.038mm, the purity is 98.00-99.999%, the utilization rate of lithium in the lithium is 98-99.95%, and the utilization rate of sulfur in the sulfur or sulfur-containing substances is 95-99.95%.

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