Method and device of producing lithium sulfide

Abstract

To provide a method and a device capable of stably producing lithium sulfide with high productivity.SOLUTION: There is disclosed a method of producing lithium sulfide. Lithium sulfide is generated by reacting a lithium-containing raw material continuously transferred along a reaction space 11 in the reaction space 11 extending in one direction and a sulfur-containing gas supplied into the reaction space 11 in a direction opposite to a transfer direction R of the lithium-containing raw material. With respect to the transfer direction R of the lithium-containing raw material, inert gas is supplied into the reaction space 11 from an upstream position 16 relative to a supply position 17 of the sulfur-containing gas, and a gas component present in the reaction space 11 is discharged outside from a position 18 between the supply position 17 of the sulfur-containing gas and the supply position 16 of the inert gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing lithium sulfide. [Background technology]

[0002] Lithium sulfide is generally synthesized by reacting hydrogen sulfide with a lithium source compound. For example, Patent Document 1 proposes a method of reacting lithium hydroxide with hydrogen sulfide using a disk dryer. In this method, the hydrogen sulfide in the disk dryer is replaced with nitrogen to terminate the reaction, and the hydrogen sulfide and water in the disk dryer are removed, after which lithium sulfide is recovered.

[0003] Patent Document 2 proposes a method for producing lithium sulfide by bringing lithium hydroxide and hydrogen sulfide into contact with each other in a reaction vessel, in which the inner wall of the reaction vessel and the lid of the reaction vessel are heated separately, thereby independently controlling the prevention of condensation of water produced by the reaction and the heating of the raw materials.

[0004] While the above-mentioned methods are batch-type methods for producing lithium sulfide, a method for producing lithium sulfide continuously is proposed in Patent Document 3. In the method described in this document, hydrogen sulfide is supplied in a countercurrent to the direction of movement of the lithium raw material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-222567 [Patent Document 2] International Publication No. 2016 / 098351 [Patent Document 3] Japanese Patent Publication No. 2023-051067 Summary of the Invention [Problem to be solved by the invention]

[0006] The methods described in Patent Documents 1 and 2 are batch processes, and therefore cannot be said to have good productivity. In the method described in Patent Document 3, the lithium raw material and hydrogen sulfide are supplied in a countercurrent manner, and water produced by the reaction may cause the lithium raw material to solidify in the lithium raw material hopper and the lithium raw material supply pipe, resulting in blockages. The occurrence of blockages is one factor that reduces the stable production and productivity of lithium sulfide. Therefore, an object of the present invention is to provide a method and an apparatus capable of producing lithium sulfide stably and with high productivity. [Means for solving the problem]

[0007] The present invention provides a method for producing lithium sulfide, comprising reacting a lithium-containing raw material continuously transported along a reaction space extending in one direction with a sulfur-containing gas supplied into the reaction space in a direction opposite to the transport direction of the lithium-containing raw material, the method comprising: The present invention provides a method for producing lithium sulfide, in which an inert gas is supplied into the reaction space from a position upstream of the supply position of the sulfur-containing gas in relation to the transport direction of the lithium-containing raw material, and gas components present in the reaction space are discharged to the outside from a position between the supply position of the sulfur-containing gas and the supply position of the inert gas.

[0008] The present invention also provides a reaction space extending in one direction, a conveying device that continuously conveys a lithium-containing raw material along the reaction space into the reaction space; a first gas supply unit located upstream in a transport direction of the lithium-containing raw material and supplying an inert gas into the reaction space; a second gas supply unit located downstream of the first gas supply unit and configured to supply a sulfur-containing gas into the reaction space; a gas discharge part that is located between the first gas supply part and the second gas supply part and that discharges gas components present in the reaction space to the outside. [Effects of the Invention]

[0009] According to the present invention, there are provided a method and an apparatus capable of producing lithium sulfide stably and with high productivity. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of a production apparatus suitably used in the method for producing lithium sulfide of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing another embodiment of a production apparatus suitably used in the method for producing lithium sulfide of the present invention. [Figure 3] FIG. 3 is a schematic diagram showing still another embodiment of a production apparatus suitably used in the method for producing lithium sulfide of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will now be described based on preferred embodiments thereof with reference to the drawings. FIG. 1 shows a lithium sulfide production apparatus suitable for use in the production method of the present invention. The production apparatus 10 shown in the figure has a reaction space 11 extending in one direction. The reaction space 11 is a space defined by a structure 12 made of a material inert to the lithium sulfide production reaction, such as a metal, ceramics, a fluorine-containing resin, or quartz. The structure 12 may be a metal coated with a fluorine-containing resin or ceramic. In the figure, the reaction space 11 extends in the horizontal direction, which is generally perpendicular to the vertical direction. However, the extension direction of the reaction space 11 is not limited to this, and the reaction space 11 may extend along the vertical direction or in another direction. Furthermore, the reaction space 11 is not limited to being linear, and may be curved or spiral as long as it extends in one direction, or may be a suitable combination of these.

[0012] In Fig. 1, the reaction space 11 has a sufficiently large dimension in the horizontal direction Y compared to the dimension in the vertical direction X (which generally coincides with the vertical direction). There are no particular limitations on the shape of the reaction space 11 when cut along the vertical direction X, and it can have various shapes, such as a circle, an ellipse, or a polygon such as a rectangle. Furthermore, the cross-sectional shape of the reaction space 11 at any position in the horizontal direction Y may be the same or different.

[0013] The volume of the reaction space 11 depends on the dimensions of the production apparatus 10, but is, for example, 1,000 cm 3 It can be more than 3,000 cm 3 or more, or 5,000 cm 3 The volume of the reaction space 11 may be, for example, 5,000,000 cm 3 It can be less than 2,500,000 cm 3 or less, or 1,000,000 cm 3 As will be described later, a transport device for transporting the lithium-containing raw material may be installed in the reaction space 11, and the volume of the reaction space 11 when the device is installed is the value obtained by subtracting the volume of the device from the volume of the reaction space 11 before the device is installed.

[0014] The manufacturing apparatus 10 may include a conveying device (not shown) that continuously conveys the lithium-containing raw material into the reaction space 11. The conveying device may be installed from the upstream end 11a to the downstream end 11b of the reaction space 11, and is configured to be able to continuously convey the lithium-containing raw material from the upstream end 11a toward the downstream end 11b in FIG. The transport device is not particularly limited in its form as long as it has a structure that allows continuous transport of the lithium-containing raw material, and any device with a structure known in the art can be used.

[0015] For example, when the reaction space 11 is inclined downward toward the downstream side, the lithium-containing raw material can be moved toward the downstream side by gravity. In this case, the degree of transport of the lithium-containing raw material can be adjusted by applying vibration to the structure 12 that defines the reaction space 11. Instead of this conveying means, a spiral rotary blade may be installed in the reaction space 11, and the lithium-containing raw material may be conveyed downstream by the rotation of the spiral rotary blade. Alternatively, a conveying means such as a belt conveyor may be installed in the reaction space 11. Other conveying means include a means for rotating or turning the structure 12 defining the reaction space 11 around a rotation axis along the extension direction of the reaction space 11, thereby conveying the lithium-containing raw material downstream. Examples of such a structure 12 include a rotary kiln, a roller hearth kiln, and a pusher kiln.

[0016] The manufacturing apparatus 10 is provided with a hopper 13 near the upstream end 11a of the reaction space 11 for supplying the lithium-containing raw material into the reaction space 11. The hopper 13 is connected to the structure 12 via a supply pipe 13a, and is capable of supplying the lithium-containing raw material into the reaction space 11.

[0017] The production apparatus 10 is provided with a recovery tank 14 that removes and recovers lithium sulfide produced by the reaction from the reaction system near the downstream end 11b of the reaction space 11. The recovery tank 14 is connected to the structure 12 via a discharge pipe 14a, so that the produced lithium sulfide can be removed from inside the reaction space 11 to the recovery tank 14.

[0018] The production apparatus 10 is equipped with a heating device 15 capable of heating at least a portion of the reaction space 11. The heating device 15 is attached to the outer surface of the structure 12 so as to cover a portion of the structure 12 that defines the reaction space 11. Specifically, the heating device 15 is disposed in a heating zone 11C that is located between an upstream zone 11A including an upstream end 11a in the reaction space 11 and a downstream zone 11B including a downstream end 11b. In the reaction space 11, the heating zone 11C is directly heated by the heating device 15. On the other hand, in the reaction space 11, the upstream zone 11A and the downstream zone 11B located respectively upstream and downstream of the heating zone 11C are not directly heated by the heating device 15, but are indirectly heated by heat conduction from the heating zone 11C. The type of heating device 15 is not particularly limited as long as it can heat the reaction space 11 defined by the structure 12, and devices with structures known in the art can be used. For example, an electric heater can be used as the heating device 15.

[0019] The manufacturing apparatus 10 includes a first gas supply unit 16 that supplies an inert gas into the reaction space 11. The first gas supply unit 16 is located upstream in the transport direction of the lithium-containing raw material (the direction indicated by the arrow R in FIG. 1 ). Specifically, the first gas supply unit 16 is located slightly downstream from the upstream end of the heating zone 11C in the reaction space 11. The first gas supply unit 16 is connected to an inert gas supply source (not shown) and is configured to supply the inert gas into the reaction space 11 at a predetermined flow rate. For this purpose, the first gas supply unit 16 may include a valve (not shown) or the like that can control the flow rate of the inert gas. The first gas supply unit 16 is configured to circulate the inert gas mainly in the same direction as the transport direction R of the lithium-containing raw material.

[0020] The manufacturing apparatus 10 includes a second gas supply unit 17 that supplies a sulfur-containing gas into the reaction space 11. The second gas supply unit 17 is located downstream in the transport direction R of the lithium-containing raw material. Specifically, the second gas supply unit 17 is located downstream of the first gas supply unit 16 in the transport direction R and slightly upstream from the downstream end of the heating zone 11C in the reaction space 11. The second gas supply unit 17 is connected to a sulfur-containing gas supply source (not shown) and is configured to supply the sulfur-containing gas into the reaction space 11 at a predetermined flow rate. For this purpose, the second gas supply unit 17 may include a valve (not shown) or the like that can control the flow rate of the sulfur-containing gas. The second gas supply unit 17 is configured to flow the sulfur-containing gas mainly in the direction opposite to the transport direction R of the lithium-containing raw material.

[0021] The manufacturing apparatus 10 includes a gas discharge unit 18 that discharges gas components present in the reaction space 11 to the outside. The gas discharge unit 18 is located between the first gas supply unit 16 and the second gas supply unit 17. Specifically, the gas discharge unit 18 is disposed downstream of the first gas supply unit 16 in the transport direction R and upstream of the second gas supply unit 17 in the transport direction R. The gas discharge unit 18 is configured to be able to discharge gases generated in the lithium sulfide manufacturing process, as well as the inert gas and sulfur-containing gas supplied into the reaction space 11, to the outside of the reaction system.

[0022] From the viewpoint of achieving the intended object of the present invention, it is preferable that gas exhaust section 18 is not arranged at a position upstream of first gas supply section 16. It is also preferable that gas exhaust section 18 is not arranged at a position downstream of second gas supply section 17. Therefore, for example, in the present invention, a plurality of first gas supply sections 16 may be provided, and in addition to or instead of these, a plurality of second gas supply sections 17 may be provided. In such cases, it is preferable that gas exhaust section 18 is not arranged between adjacent first gas supply sections 16. Similarly, it is preferable that gas exhaust section 18 is not arranged between adjacent second gas supply sections 17.

[0023] In the manufacturing apparatus 10, the first gas supply unit 16 and the second gas supply unit 17 are provided at the position where the heating device 15 is disposed. Specifically, the first gas supply unit 16 and the second gas supply unit 17 are provided in a heating zone 11C formed by heating the reaction space 11 by the heating device 15. A gas exhaust unit 18 is provided between the two gas supply units 16 and 17. Therefore, the gas exhaust unit 18 is also provided in the heating zone 11C. Providing the first gas supply unit 16 and the second gas supply unit 17 in the heating zone 11C has the advantage that an inert gas and a sulfur-containing gas can be supplied to the reaction space 11 while heating, and the internal temperature of the reaction space 11 can be maintained by these gases, thereby efficiently promoting the reaction.

[0024] The manufacturing apparatus 10 may further include a third gas supply unit 19 at the outlet of the reaction space 11 or downstream thereof. In the embodiment shown in FIG. 1 , the third gas supply unit 19 is connected to the middle of the lithium sulfide discharge pipe 14a, downstream of the outlet of the reaction space 11. The third gas supply unit 19 is connected to an inert gas supply source (not shown) and is configured to supply an inert gas, the same or different from the inert gas supplied from the first gas supply unit 16, into the reaction space 11 at a predetermined flow rate. For this purpose, the third gas supply unit 19 may include a valve (not shown) or the like capable of controlling the flow rate of the inert gas. The third gas supply unit 19 is configured to flow the inert gas mainly in a direction opposite to the transport direction R of the lithium-containing raw material.

[0025] Next, a method for producing lithium sulfide using the production apparatus 10 having the above configuration will be described. First, an inert gas is supplied from the first gas supply unit 16, the second gas supply unit 17, and the third gas supply unit 19 into the reaction space 11 defined by the structure 12 provided in the manufacturing apparatus 10, and the gas exhaust unit 18 is opened to exhaust the inert gas from the reaction space 11 to the outside. This allows the inert gas to flow through the reaction space 11. As the inert gas, an inert gas that does not affect the lithium sulfide production reaction can be used. Specific examples of the inert gas include nitrogen gas and rare gases such as helium and argon. Note that in the present invention, the inert gas may contain gases other than the inert gas. Examples of gases other than the inert gas include reducing gases such as hydrogen.

[0026] Once the inert gas has sufficiently spread throughout the reaction space 11, the heating device 15 is operated to heat the reaction space 11. The heating temperature can be set to a temperature at which the lithium sulfide production reaction proceeds smoothly. The heating temperature will be described later.

[0027] When the reaction space 11 reaches the set temperature, the type of gas supplied from the second gas supply unit 17 is switched from an inert gas to a sulfur-containing gas, and the sulfur-containing gas is supplied into the reaction space 11. At this time, the first gas supply unit 16 and the third gas supply unit 19 continue to supply the inert gas into the reaction space 11. The sulfur-containing gas supplied into the reaction space 11 flows mainly along the transport direction R of the lithium-containing raw material, and also flows slightly in the direction opposite to the transport direction R. The inert gas supplied into the reaction space 11 from the first gas supply unit 16 flows mainly along the transport direction R of the lithium-containing raw material, and also flows slightly in the direction opposite to the transport direction R. The inert gas supplied into the reaction space 11 from the third gas supply unit 19 flows mainly along the direction opposite to the transport direction R of the lithium-containing raw material, and also flows slightly in the transport direction R. The sulfur-containing gas may be a gas of a compound containing sulfur element, or a mixed gas in which the gas of a compound containing sulfur element is diluted with an inert gas. From the viewpoint of smoothly proceeding the lithium sulfide production reaction, for example, hydrogen sulfide, sulfur gas, carbon disulfide, and sulfur oxides may be used as the compound containing sulfur element. As the inert gas for diluting the gas of the compound containing sulfur element, the inert gases exemplified as the inert gases supplied from the first gas supply unit 16 and the third gas supply unit 19 described above may be used. From the viewpoint of preventing the lithium sulfide production reaction from proceeding too rapidly, it is preferable to use hydrogen sulfide diluted with an inert gas as the sulfur-containing gas.

[0028] When the sulfur-containing gas contains, for example, hydrogen sulfide, the concentration of hydrogen sulfide in the sulfur-containing gas is preferably 10 vol% or more and 100 vol% or less. A hydrogen sulfide concentration of 100 vol% means that the sulfur-containing gas consists only of hydrogen sulfide. When the hydrogen sulfide concentration is less than 100 vol%, the sulfur-containing gas is a mixed gas in which hydrogen sulfide is diluted with an inert gas such as argon or nitrogen or a reducing gas such as hydrogen.

[0029] From the viewpoint of suppressing a rapid sulfurization reaction while maintaining reactivity with the lithium-containing raw material, the concentration of hydrogen sulfide in the sulfur-containing gas can be 50 vol% or more and 90 vol% or less, and may be 60 vol% or more and 80 vol% or less.

[0030] The supply amount of the sulfur-containing gas can be set to an appropriate value depending on the volume of the reaction space 11. When the reaction space 11 has the volume described above, for example, the supply amount of the sulfur-containing gas can be set to, for example, 500 cm 3 / min or more, and can be 800cm 3 / min or more, or 1,000 cm 3 The supply rate of the sulfur-containing gas may be, for example, 12,000,000 cm3 / min or more. 3 / min or less, and can be 10,000,000 cm 3 / min or less, or 8,000,000 cm 3 / min or less. Note that this supply rate is the value at 25°C and 1 atm (hereinafter, when the gas supply rate is explained, the value under these conditions is meant).

[0031] By keeping the ratio of the supply amount of the gas supplied from the first gas supply unit to the supply amount of the gas supplied from the second gas supply unit within a predetermined range, the fixation of the lithium-containing raw material caused by the inflow of water generated in association with the production of lithium sulfide into the reaction space upstream region 11A is suppressed, and the lithium-containing raw material and the sulfur-containing gas can be efficiently reacted with each other. For example, when the supply amount (cm ) of the gas supplied from the first gas supply unit 16 is 3 / min) from the second gas supply unit 17. 3 / min) is preferably 0.10 or more, more preferably 0.25 or more, and particularly preferably 0.50 or more. On the other hand, the supply rate (cm 3 / min) from the second gas supply unit 17. 3 / min) is preferably, for example, 20 or less, more preferably 10 or less, and particularly preferably 5 or less.

[0032] While the inert gas and the sulfur-containing gas are being supplied, the reaction space 11 can be communicated with the outside of the reaction system. At this time, the gas discharge part 18 is in an open state. Next, the supply pipe 13a connecting the hopper 13 and the reaction space 11 is opened, and the lithium-containing raw material stored in the hopper 13 is continuously supplied into the reaction space 11, thereby allowing the reaction space 11 to be continuously transported. In this specification, the term "continuous transfer" means that the production method of the present invention is a continuous reaction, not a batch reaction. Therefore, in the production method of the present invention, the lithium-containing raw material and the sulfur-containing gas, which are reactants, are continuously supplied into the reaction space 11. Performing the production method of the present invention in a continuous manner is advantageous from the viewpoint of increasing the production efficiency of lithium sulfide compared to a batch method.

[0033] The lithium-containing raw material is generally supplied into the reaction space 11 in a particulate solid state, and undergoes a solid-gas reaction with the sulfur-containing gas. From the viewpoint of promoting the reaction for producing lithium sulfide, the particle size of the lithium-containing raw material is determined by a volume cumulative particle size D at 50% by volume of the cumulative volume measured by a laser diffraction / scattering particle size distribution measurement method. 50 The volume cumulative particle diameter D can be 500 μm or less, may be 400 μm or less, or may be 300 μm or less. 50 may be 4 μm or more, or 50 μm or more, or 100 μm or more.

[0034] The supply rate of the lithium-containing raw material can be appropriately set depending on the volume of the reaction space 11 and the supply rate of the sulfur-containing gas. When the volume of the reaction space 11 is within the above-mentioned range, for example, the supply rate of the lithium-containing raw material can be 0.1 g / min or more, 0.5 g / min or more, or 0.75 g / min or more. The supply rate of the lithium-containing raw material can be 1,200 g / min or less, 1,000 g / min or less, or 750 g / min or less.

[0035] The lithium-containing raw material is preferably a compound that contains lithium element and is solid at room temperature (25°C). Examples of the lithium-containing raw material include, but are not limited to, lithium hydroxide, lithium carbonate, and lithium oxide. It is preferable to use, for example, lithium hydroxide as the lithium-containing raw material because it can produce lithium sulfide at a relatively low temperature.

[0036] The lithium-containing raw material is transported in the reaction space 11 in the transport direction R. At the same time, the sulfur-containing gas supplied from the second gas supply unit 17 into the reaction space 11 flows in the direction opposite to the transport direction R.

[0037] According to the production method of the present invention, the lithium-containing raw material and the sulfur-containing gas are brought into countercurrent contact with each other to cause a reaction. The main reaction between the lithium-containing raw material and the sulfur-containing gas is a sulfurization reaction represented by the following (1) to (3). (1) 2LiOH+H2S → Li2S+2H2O↑ (2) Li2CO3+H2S → Li2S+H2O↑+CO2↑ (3) Li2O+H2S → Li2S+H2O↑ As is clear from reaction formulas (1) to (3), these reactions involve contacting a solid lithium-containing raw material with a sulfur-containing gas in a dry state without using a solvent such as water. Furthermore, as is clear from reaction formulas (1) to (3), these reactions produce water. The production of water causes the inconvenience of contributing to the solidification of the lithium-containing raw material. The solution to this inconvenience will be described later.

[0038] When the lithium-containing raw material is brought into contact with the sulfur-containing gas in a sufficiently heated state, the reaction proceeds further. The lithium-containing raw material is preferably heated to a temperature range where the lithium-containing raw material does not melt, particularly to a temperature range of "the melting point of the raw material - 10°C" or less. For example, when lithium hydroxide is used as the lithium-containing raw material, since the melting point of lithium hydroxide is 462°C, it is preferable to heat the reaction space 11 so that the product temperature of the lithium-containing raw material falls within the following temperature range. The specific temperature range is preferably 100°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher. Meanwhile, the product temperature may be, for example, 450°C or lower, 430°C or lower, or 400°C or lower.

[0039] To heat the reaction space 11 to the above temperature range, the temperature of the inner wall surface of the structure 12 in the heating zone 11C is preferably, for example, 100° C. or higher, more preferably 150° C. or higher, and even more preferably 200° C. or higher. On the other hand, the temperature may be, for example, 450° C. or lower, 430° C. or lower, or 400° C. or lower. The temperature of the inner wall surface of the structure 12 in the heating zone 11C can be considered to be approximately the same as the product temperature of the lithium-containing raw material. Therefore, if the temperature of the inner wall surface of the structure 12 in the heating zone 11C is 100°C or higher and 450°C or lower, the reactions (1) to (3) can be sufficiently promoted.

[0040] The temperature in reaction space 11 in heating zone 11C is preferably as described above, and the temperature in reaction space 11 in upstream zone 11A is preferably, for example, 50° C. or higher, more preferably 100° C. or higher, and particularly preferably 150° C. or higher. On the other hand, the temperature is preferably, for example, 450° C. or lower, more preferably 400° C. or lower, and particularly preferably 350° C. or lower. Furthermore, the temperature in the reaction space 11 in the downstream region 11B can be set to be the same as the temperature in the reaction space 11 in the upstream region 11A described above, and therefore will not be described here.

[0041] In the production method of the present invention, while the reaction space 11 is being heated and the lithium sulfide production reaction continues, an inert gas is supplied into the reaction space 11 from a position (first gas supply unit 16) upstream of the second gas supply unit 17, which is the supply position of the sulfur-containing gas. Since the inert gas flows mainly along the transport direction R of the lithium-containing raw material, the flow of the inert gas prevents water generated with the production of lithium sulfide from flowing back in the direction opposite to the transport direction R. As a result, contact between the water and the lithium-containing raw material is effectively suppressed, which effectively suppresses solidification of the lithium-containing raw material. Furthermore, the flow of the inert gas effectively prevents unreacted sulfur-containing gas from reaching the hopper 13 and the supply pipe 13a, and can effectively prevent solidification of the lithium-containing raw material in the hopper, which would be caused by the unintended occurrence of a reaction to produce lithium sulfide in the hopper 13 and the supply pipe 13a.

[0042] The supply amount of the inert gas can be set to an appropriate value depending on the volume of the reaction space 11 and the amount of water to be produced. When the reaction space 11 has the volume described above, for example, the supply amount of the inert gas can be set to, for example, 50 cm 3 / min or more, and can be 80cm 3 / min or more, or 100cm 3 The supply rate of the inert gas may be, for example, 240,000,000 cm 3 / min or less, and can be 200,000,000 cm 3 / min or less, or 160,000,000 cm 3 This supply amount does not include the amount of inert gas supplied from the third gas supply unit 19, which will be described later.

[0043] In the production method of the present invention, gas components present in the reaction space 11, such as water, inert gas, and unreacted hydrogen sulfide, are discharged to the outside from a position between the second gas supply unit 17, which is the supply position of the sulfur-containing gas, and the first gas supply unit 16, which is the supply position of the inert gas, i.e., the gas discharge unit 18. In particular, when the gas discharge unit 18 is provided in the heating zone 11C, water generated by the lithium sulfide production reaction is easily vaporized by heating, facilitating the release of water outside the reaction system. This also effectively prevents contact between water and the lithium-containing raw material, thereby effectively preventing solidification of the lithium-containing raw material. In addition, the generation of lithium-containing raw materials, such as lithium hydroxide, due to the reverse reaction of the generated lithium sulfide can be effectively prevented.

[0044] When the distance between the first gas supply unit 16 and the second gas supply unit 17 is L1 and the distance between the first gas supply unit 16 and the gas exhaust unit 18 is L2, the value of L2 / L1 can be, for example, 0.1 or more, or may be 0.2 or more, or may be 0.3 or more. The value of L2 / L1 can be 0.9 or less, or may be 0.8 or less, or may be 0.7 or less. When L2 / L1 is within the above range, the lithium sulfide production reaction can proceed efficiently.

[0045] When the gas present in the reaction space 11 is to be released from the gas exhaust section 18, the gas may be released by the internal pressure of the reaction space 11, or the gas may be actively released by connecting the gas exhaust section 18 to a suction source (not shown).

[0046] If the gas released from the gas outlet 18 contains unreacted hydrogen sulfide, it is preferable to treat the released gas by completely burning it using a burner or the like, neutralizing the gas with a basic aqueous solution, and converting it into sulfate or the like.

[0047] As described above, according to the production method of the present invention, the synergistic effect of supplying an inert gas into the reaction space 11 and releasing the gas from the reaction space 11 to the outside of the reaction system, along with countercurrent contact between the lithium-containing raw material and the sulfur-containing gas, dramatically improves the reaction efficiency and production stability in the continuous production of lithium sulfide. To further enhance this advantage, it is preferable not to discharge gas components present in the reaction space 11 to the outside from a position upstream of the supply position of the inert gas from the first gas supply unit 16. It is also preferable not to discharge gas components present in the reaction space 11 to the outside from a position downstream of the supply position of the sulfur-containing gas from the second gas supply unit 17. Therefore, for example, in the production method of the present invention, when a plurality of first gas supply units 16 and / or a plurality of second gas supply units 17 are provided, it is preferable not to discharge gas from a position between adjacent first gas supply units 16. Similarly, it is preferable not to discharge gas from a position between adjacent second gas supply units 17.

[0048] In the production method of the present invention, during the reaction between the lithium-containing raw material and the sulfur-containing gas, an inert gas of the same kind or a different kind as the inert gas supplied from the first gas supply unit 16 can be supplied into the reaction space 11 from the outlet of the reaction space 11 or a position downstream thereof, for example, from the third gas supply unit 19. This can effectively prevent water from unintentionally entering the reaction space 11 from outside the reaction system. The supply amount of the inert gas from the third gas supply unit 19 can be set to an appropriate value depending on the supply amount of the inert gas from the first gas supply unit 16, the volume of the reaction space 11, and the amount of water produced. When the reaction space 11 has the volume described above, for example, the supply amount of the inert gas from the third gas supply unit 19 can be set to, for example, 50 cm 3 / min or more, and can be 80cm 3 / min or more, or 100cm 3 The supply rate of the inert gas may be, for example, 240,000,000 cm 3 / min or less, and can be 200,000,000 cm 3 / min or less, or 160,000,000 cm 3 / min or less.

[0049] The lithium sulfide produced in the reaction space 11 is recovered through the discharge pipe 14a into the recovery tank 14. However, when the produced lithium sulfide is used as a raw material to continuously produce another substance, it is also possible to subject the lithium sulfide to the production process of that substance without recovering it.

[0050] When lithium sulfide is recovered and stored in recovery tank 14, it is preferable to heat the temperature of the inner wall surface of recovery tank 14 to 100°C or higher. By heating the inner wall surface of recovery tank 14, the water in recovery tank 14 can be vaporized, and the reaction between the condensed water and lithium sulfide, which is a reaction product, and the generation of lithium hydroxide can be effectively suppressed. Furthermore, the aggregation of lithium sulfide and its adhesion to the inner wall surface of recovery tank 14 can be effectively suppressed.

[0051] Instead of or in addition to heating the inner wall surface of the collection tank 14, an inert gas may be supplied into the collection tank 14. This allows water to be discharged outside the collection tank 14 while accompanying the inert gas.

[0052] Although the present invention has been described above based on the preferred embodiments, the present invention is not limited to the above embodiments. For example, in the embodiment of the manufacturing apparatus 10 shown in FIG. 1, only one gas exhaust section 18 is provided between the first gas supply section 16 and the second gas supply section 17. Alternatively, as shown in FIG. 2, a plurality of gas exhaust sections 18a, 18b, and 18c may be provided between the first gas supply section 16 and the second gas supply section 17. 1, second gas supply unit 17 is disposed at a position slightly upstream from the downstream end of heating zone 11C, but instead, as shown in Fig. 3, it may be disposed in downstream zone 11B located downstream of heating zone 11C. Alternatively, first gas supply unit 16 may be disposed in upstream zone 11A located upstream of heating zone 11C. Furthermore, in the embodiment of the manufacturing apparatus 10 shown in Figure 1, the heating device 15 is attached only to the heating area 11C in the reaction space 11, but instead, the heating device may be attached to the structure 12 so that the entire reaction space 11 is heated. [Explanation of symbols]

[0053] 10 Lithium sulfide manufacturing equipment 11 Reaction Space 12 Structure 13 Hopper 14 Collection tank 15 Heating device 16 First gas supply section 17 Second gas supply section 18 Gas exhaust section 19 Third Gas Supply Section

Claims

1. A method for producing lithium sulfide, comprising: reacting a lithium-containing raw material continuously transported along a reaction space extending in one direction with a sulfur-containing gas supplied into the reaction space in a direction opposite to a transport direction of the lithium-containing raw material, to generate lithium sulfide, a supply position of the sulfur-containing gas into the reaction space from a position upstream of the supply position of the sulfur-containing gas in relation to a transport direction of the lithium-containing raw material, and a gas component present in the reaction space is discharged to the outside from a position between the supply position of the sulfur-containing gas and the supply position of the inert gas.

2. The production method according to claim 1 , wherein the sulfur-containing gas and the inert gas are each supplied to a heated zone formed by heating at least a portion of the reaction space, and the gas components are discharged from the heated zone.

3. 3. The method according to claim 1, wherein an inert gas of the same kind or a different kind as the inert gas is supplied into the reaction space from an outlet of the reaction space or a position downstream thereof.

4. A reaction space extending in one direction; a conveying device that continuously conveys a lithium-containing raw material along the reaction space into the reaction space; a first gas supply unit located upstream in a transport direction of the lithium-containing raw material and supplying an inert gas into the reaction space; a second gas supply unit located downstream of the first gas supply unit and configured to supply a sulfur-containing gas into the reaction space; a gas discharge unit located between the first gas supply unit and the second gas supply unit and configured to discharge gas components present in the reaction space to the outside.

5. Further comprising a heating device capable of heating at least a part of the reaction space, 5. The manufacturing apparatus according to claim 4, wherein the first gas supply unit and the second gas supply unit are provided in a heating zone formed by heating the reaction space by the heating device, and the gas exhaust unit is provided between the two gas supply units.

6. The manufacturing apparatus according to claim 4 or 5, further comprising a third gas supply unit at an outlet of the reaction space or downstream thereof, which supplies an inert gas of the same kind or a different kind to the inert gas into the reaction space.

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