Sintering process, sintering system device, target product and use

Abstract

The present application provides a sintering process, a sintering system device, a target product and a use. The sintering process comprises: subjecting a water-containing and sulfur-containing substance to primary sintering to remove a first substance, and then subjecting same to secondary sintering to remove a second substance, so as to obtain a target product, wherein the primary sintering is n-stage sintering, n being an integer greater than or equal to 2; and the first substance comprises water, and the second substance comprises sulfur. In the sintering process of the present application, the traditional procedure of expansion drying can be omitted, and therefore the production costs and energy consumption are reduced, and the production process is simplified; and by sequentially performing the primary sintering and the secondary sintering, moisture and sulfur in the water-containing and sulfur-containing substance can be effectively removed, thereby reducing the sulfur content of the target product and the phenomenon of moisture condensation.

Description

A sintering process, sintering system device, target product and application Technical Field

[0001] The present application belongs to the field of battery technology and relates to a sintering process, a sintering system device, a target product and applications. Background Art

[0002] Lithium iron phosphate (LIFP), a key cathode material for lithium-ion batteries, has attracted considerable attention due to its lack of expensive rare metals like cobalt, excellent electrochemical properties, and broad application prospects. With the continuous development of society and growing awareness of environmental protection, the demand for high-performance, high-safety battery materials continues to increase. Iron phosphate (IFP), a key precursor material for LFP, continues to rise. As lithium-ion battery performance requirements continue to increase, so too do the demands placed on the cost, quality, and performance of IFP precursors. Therefore, optimizing IFP production processes and improving product quality and efficiency have become pressing challenges.

[0003] In the traditional iron phosphate production process, a filter press is often used to filter and compact the aqueous iron phosphate solution to form an iron phosphate filter cake containing less water. Then, in order to remove the free water in the filter cake, a flash drying process is usually required. During the flash drying process, the water in the filter cake is evaporated, resulting in a relatively dry iron phosphate filter cake. The dried iron phosphate filter cake is then sent to a rotary kiln for sintering. However, the flash drying process requires a large amount of energy and equipment investment, increasing production costs and energy consumption. In addition, the drying process in the traditional process is relatively cumbersome, increasing production time and complexity, and reducing production efficiency. In addition to the drying problem, controlling the sulfur content in the traditional production process is also a challenge. During the iron phosphate production process, sulfur may exist in the iron phosphate in the form of impurities. Iron phosphate products with high sulfur content may not meet the requirements of specific industries, reducing the market competitiveness of the product.

[0004] Moreover, when a single hot kiln is used for sintering, free water, crystallization water and impurity S are simultaneously degased into gaseous form by high temperature and pumped into the dust collecting bin of the hot kiln through negative pressure. Since the negative pressure conveying process will cause mixed materials to be pumped into the dust collecting bin, the materials in the dust collecting bin will condense when they are cooled with gaseous water vapor and sulfide and reach the dew point. If they continue to return to the hot kiln for sintering, more S will be introduced. If they are not returned to the rotary kiln, there are two ways to deal with this part of the material: 1. scrap treatment; 2. rework of the S-containing material, which increases production costs. At the same time, condensation can easily cause poor equipment operation, thereby interrupting the production rhythm.

[0005] Therefore, there is an urgent need for a simple process that can effectively remove moisture, reduce sulfur content, reduce the occurrence of condensation, and at the same time reduce production costs and energy consumption.

[0006] Summary of the Invention

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] In response to the shortcomings of the existing technology, the present application aims to provide a sintering process, a sintering system, a target product, and its application. The sintering process of the present application can omit the traditional flash drying process, reducing production costs and energy consumption, and simplifying the production process. Through sequential one-stage and two-stage sintering, it can effectively remove water and sulfur from water-containing and sulfur-containing substances, reducing the sulfur content in the target product and minimizing the occurrence of condensation.

[0009] To achieve this goal, this application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a sintering process, the sintering process comprising:

[0011] The water-containing and sulfur-containing substance is subjected to a first-stage sintering to remove a first substance, and then subjected to a second-stage sintering to remove a second substance, thereby obtaining a target product;

[0012] The one-stage sintering is n-stage sintering, where n≥2 and n is an integer (for example, it can be 2, 3, 4, 5, 6, 7, 8, 9, 10 or 15 stages, etc.);

[0013] The first substance includes water, and the second substance includes sulfur.

[0014] The present application provides a sintering process, which firstly removes water from water-containing and sulfur-containing substances through n-stage sintering in a first-stage sintering process; then further removes sulfur through a second-stage sintering process to reduce the sulfur content in the target product; in addition, the first-stage sintering and the second-stage sintering process can also increase the BET surface area of ​​the target product, thereby improving product quality;

[0015] By adopting the sintering process of the present application, the traditional flash drying process can be omitted, production costs and energy consumption can be reduced, the production process can be simplified, production efficiency can be improved, and it is also beneficial to save energy and reduce environmental pollution. The flash drying process usually requires a large amount of thermal energy. Omitting this process can reduce energy consumption and carbon dioxide emissions; and in this sintering process, gaseous sulfides and water vapor do not contact the material at the same time, which can reduce condensation, reduce the generation of waste, improve production continuity, improve the purity and quality of the target product, reduce the impurity content, and make the product more in line with market demand and industry standards; in addition, the sintering process has a wide range of applications and can dehydrate and desulfurize a variety of water-containing and sulfur-containing substances.

[0016] In one embodiment, the water-containing sulfur-containing substance includes free water and a sulfur-containing component, and the sulfur-containing component includes at least one of sulfur-containing ferric phosphate dihydrate, sulfur-containing cobalt carbonate, sulfur-containing basic cobalt carbonate and sulfur-containing cobalt hydroxide, and can be sulfur-containing ferric phosphate dihydrate.

[0017] It should be noted that during the first-stage sintering, free water is removed from the hydrous and sulfur-containing substances. Simultaneously, water of crystallization is removed from the sulfur-containing ferric phosphate dihydrate. H₂O generated during the decomposition of the sulfur-containing basic cobalt carbonate and sulfur-containing cobalt hydroxide during the first-stage sintering process is also removed. In other words, the water removed during the first-stage sintering includes at least one of free water, water of crystallization, and water generated by thermal decomposition. The second-stage sintering removes sulfur from the sulfur-containing components. Furthermore, carbon dioxide is removed from the sulfur-containing cobalt carbonate and sulfur-containing basic cobalt carbonate during the second-stage sintering.

[0018] The present application does not specifically limit the preparation process of sulfur-containing ferric phosphate dihydrate, including but not limited to the ammonia method, the sodium method and the iron oxide red process.

[0019] In one embodiment, based on the total mass of the water-containing and sulfur-containing substances as 100%, the mass content of the free water is less than 40%, for example, it can be 39%, 36%, 35%, 32%, 30%, 25%, 20% or 10%, etc.

[0020] In the present application, when the free water content in the water-containing sulfur-containing material is less than 40%, the free water content is relatively small, and the dispersion effect is better during the first stage of sintering, and there will be no agglomeration. If the free water content is too much, it is easy to cause the feed to get stuck during the first stage of sintering, and the material cannot be effectively dispersed, resulting in agglomerated material.

[0021] In one embodiment, the content of crystal water in the sulfur-containing ferric phosphate dihydrate is 19-21%, for example, 19%, 19.5%, 20%, 20.5% or 21%.

[0022] In one embodiment, based on the total mass of the aqueous sulfur-containing substance as 100%, the mass content of sulfur in the aqueous sulfur-containing substance is 0.1-1.0%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1.0%, etc.

[0023] In this application, if the S content is too low, S removal can be completed without multi-stage hot kiln sintering. If the S content is too high, it is difficult to remove, which may easily cause the S content of the product to be too high, and the process should be adjusted in the synthesis stage.

[0024] In one embodiment, the particle size D50 of the sulfur-containing component is 7-50 μm, for example, 7 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm or 45 μm.

[0025] In the present application, when the particle size D50 of the sulfur-containing component is 7-50 μm, the particles are relatively large, the moisture content of the material is low, and it is easy to disperse during feeding without generating a large number of particle agglomerations, thereby reducing lumps.

[0026] In one embodiment, the n-stage sintering includes the first stage sintering, the second stage sintering and the x-stage sintering, where x≥3 and x is an integer, for example, 3, 4, 5, 6, 7, 8, 9, 10 or 15. In this case, n≥3.

[0027] It should be noted that the "xth stage" refers to the stages of sintering in the "n" stage, excluding the first and second stages. For example, when n = 6, the first stage of sintering is a six-stage sintering, comprising the first, second, third, fourth, fifth, and sixth stages. In this case, the "xth stage" is the third, fourth, fifth, and sixth stages. The maximum value of "x" in the "xth stage" is the same as the value of "n."

[0028] In one embodiment, the temperature of the first stage sintering and the second stage sintering is independently 150-250°C, for example, 150°C, 170°C, 200°C, 220°C or 250°C.

[0029] In this application, the temperature settings of the first and second stage sintering in the first stage sintering are more important. If the temperature is too high, the water-containing and sulfur-containing substances will quickly agglomerate during the dehydration process, affecting the dehydration and desulfurization process; if the temperature is too low, it will be difficult to remove the water quickly, and there is a risk of residual water when entering the second stage sintering.

[0030] The term "independently" means that the temperature of the first stage sintering is 150-250°C, and the temperature of the second stage sintering is 150-250°C, and the selection of the two temperatures does not interfere with each other and can be the same or different. The rest is the same.

[0031] In one embodiment, the temperature of the second stage sintering is higher than the temperature of the first stage sintering.

[0032] In the present application, the temperature of the second stage sintering is limited to be higher than the temperature of the first stage sintering in order to allow free water to be removed gradually and avoid agglomeration.

[0033] In one embodiment, the time for the first stage sintering and the second stage sintering is independently 0.05-0.50h, for example, 0.05h, 0.1h, 0.15h, 0.2h, 0.25h, 0.3h, 0.35h, 0.4h, 0.45h or 0.5h, etc., and can be optionally 0.10-0.30h.

[0034] In this application, when the time for the first stage sintering and the second stage sintering is independently 0.05-0.50h, the removal of free water can be completed. If the time is too short, the free water cannot be effectively removed, affecting the removal of water such as crystallization water during subsequent sintering. If the time is too long, it will cause energy waste.

[0035] In one embodiment, the temperature of the x-th stage sintering is independently 200-500°C, for example, 200°C, 220°C, 250°C, 300°C, 350°C, 400°C or 450°C.

[0036] In the present application, when the temperature of the x-stage sintering is independently 200-500°C, the water (such as crystallization water) can be removed without removing S. If the temperature is too low, it is difficult to remove the crystallization water, resulting in the removal of S and crystallization water at the same time in the second-stage sintering, which can easily lead to condensation. If the temperature is too high, the S is easily removed while dehydration is carried out in the first-stage sintering, which can lead to condensation.

[0037] In one embodiment, the x-th stage sintering time is independently 0.05-0.50 h, for example, 0.05 h, 0.1 h, 0.15 h, 0.2 h, 0.25 h, 0.3 h, 0.35 h, 0.4 h, 0.45 h or 0.5 h, etc., and can be optionally 0.10-0.30 h.

[0038] In this application, when the time of the x-stage sintering is independently 0.05-0.50h, the removal of moisture (such as crystallization water) can be effectively completed. If the time is too short, the crystallization water cannot be effectively removed in the first stage of sintering, and the removal is delayed to the second stage of sintering. Dehydration and desulfurization are carried out in the second stage of sintering. Water vapor encounters sulfide and causes condensation, affecting product quality. If the time is too long, it will cause energy waste.

[0039] In one embodiment, in the n-stage sintering, the sintering time of each stage is the same.

[0040] In one embodiment, n satisfies the following condition: 4≤n≤8, for example, it can be 4, 5, 6, 7 or 8.

[0041] In the present application, when n is 4≤n≤8, the sintering stage is appropriate, which can complete the water removal without causing much energy waste.

[0042] In one embodiment, the calcined product obtained by the first-stage sintering contains trace amounts of water, but does not cause condensation. Based on the total mass of the calcined product as 100%, the mass content of water in the calcined product is less than 1.5%, for example, 1.4%, 1.2%, 1.0%, or 0.5%.

[0043] In one embodiment, the second stage sintering is m-level sintering, where m≥2 and m is an integer, for example, it can be 2nd level, 3rd level, 4th level, 5th level, 6th level, 7th level, 8th level, 9th level, 10th level or 15th level.

[0044] In the present application, when the two-stage sintering is divided into m-stage sintering, the desulfurization effect can be improved by adjusting the sintering temperature of each stage. The sintering temperature of each stage in the m-stage sintering can be the same or different.

[0045] In one embodiment, the m-stage sintering includes the first stage sintering, the second stage sintering and the y-stage sintering, where y≥3 and y is an integer, and y can be, for example, three, four, five, six, seven, eight, nine, ten or fifteen, etc. In this case, m≥3.

[0046] It should be noted that the y-stage sintering refers to the stages of sintering in the m-stage sintering, excluding the first and second stages. For example, when m=6, the first stage of sintering is a six-stage sintering, which includes the first, second, third, fourth, fifth, and sixth stages. In this case, the y-stage sintering is the third, fourth, fifth, and sixth stages. The maximum value of y in the y-stage sintering is the same as the value of m.

[0047] In one embodiment, the temperatures of the first stage sintering and the second stage sintering are independently 550-750°C, for example, 550°C, 570°C, 600°C, 650°C, 700°C or 750°C.

[0048] In the present application, when the temperatures of the first stage sintering and the second stage sintering are independently 550-750°C, the impurity S can be effectively removed. If the temperature is too low, there is no desulfurization effect. If the temperature is too high, the energy consumption is too high and the product is easily overburned.

[0049] In one embodiment, the time of the first stage sintering and the second stage sintering is independently 0.10-0.50h, for example, it can be 0.1h, 0.15h, 0.2h, 0.25h, 0.3h, 0.35h, 0.4h, 0.45h or 0.5h, etc., and can be optionally 0.10-0.30h.

[0050] In this application, when the time of the first stage sintering and the second stage sintering is independently 0.10-0.50h, if the time is too short, the desulfurization effect is poor and the S content of the product is high. If the time is too long, it is easy to cause the product to be overburned and the BET specific surface area is low.

[0051] In one embodiment, the temperature of the y-th stage sintering is independently 600-750°C, for example, 600°C, 620°C, 650°C, 700°C, 720°C or 750°C.

[0052] In this application, when the temperature of the y-stage sintering is independently 600-750°C, the impurity S can be effectively removed. If the temperature is too low, there is no desulfurization effect. If the temperature is too high, the energy consumption is too high and it is easy to cause the product to be overburned, which in turn causes a low BET specific surface area.

[0053] In one embodiment, the y-stage sintering time is independently 0.10-0.50 h, for example, 0.1 h, 0.15 h, 0.2 h, 0.25 h, 0.3 h, 0.35 h, 0.4 h, 0.45 h or 0.5 h, etc., and can be optionally 0.10-0.30 h.

[0054] In the present application, when the y-stage sintering time is independently 0.10-0.50h, if the time is too short, the desulfurization effect is poor and the S content of the product is high; if the time is too long, the product is easily overburned.

[0055] In one embodiment, in the m-stage sintering, the sintering time of each stage is the same.

[0056] In one embodiment, m satisfies the following condition: 4≤m≤8, for example, it can be 4, 5, 6, 7 or 8.

[0057] In the present application, when m is 4≤m≤8, desulfurization can be completed without causing overburning of the product.

[0058] As an optional technical solution of the present application, the sintering process specifically includes:

[0059] The aqueous sulfur-containing slurry is subjected to filter pressing and crushed to obtain an aqueous sulfur-containing substance, wherein the aqueous sulfur-containing substance includes free water and a sulfur-containing component, wherein the sulfur-containing component includes at least one of sulfur-containing ferric phosphate dihydrate, sulfur-containing cobalt carbonate, sulfur-containing basic cobalt carbonate, and sulfur-containing cobalt hydroxide; the aqueous sulfur-containing substance is then subjected to a first-stage sintering to remove water, and then subjected to a second-stage sintering to remove sulfur and / or carbon dioxide, to obtain a target product;

[0060] The first stage sintering is n-stage sintering, where 4≤n≤8 and n is an integer; the n-stage sintering includes a first stage sintering, a second stage sintering and an x-stage sintering, where 3≤x≤8 and x is an integer; the temperatures of the first stage sintering and the second stage sintering are independently 150-250° C., and the temperature of the x-stage sintering is independently 200-500° C.

[0061] The two-stage sintering is m-level sintering, 4≤m≤8 and m is an integer; the m-level sintering includes first-level sintering, second-level sintering and y-level sintering, 3≤y≤8 and y is an integer, the temperatures of the first-level sintering and the second-level sintering are independently 550-750°C, and the temperature of the y-level sintering is independently 600-750°C.

[0062] In one embodiment, after the second stage sintering, the product undergoes screening, demagnetization, and packaging processes.

[0063] In a second aspect, the present application provides a sintering system device, wherein the sintering process described in the first aspect is performed in the sintering system device;

[0064] The sintering system device includes a first-stage hot kiln and a second-stage hot kiln connected in sequence, and the first-stage hot kiln is provided with at least two sintering constant temperature zones (for example, 2, 3, 4, 5, 6, 7, 8, 10 or 15, etc.).

[0065] In one embodiment, the inclination angles of the first-stage hot kiln and the second-stage hot kiln are independently 0-2°, and are not 0.

[0066] In the present application, the first-stage hot kiln and the second-stage hot kiln transport materials forward by the set inclination angle and the driving force generated by the continuous rotation.

[0067] In one embodiment, the one-stage hot kiln includes a first kiln head and a first kiln body connected in sequence, the first kiln head is provided with a feed port, a discharge port and a dust outlet, the feed port of the first kiln head is connected to a feed pipeline, the discharge port of the first kiln head is connected to the feed end of the first kiln body, and the dust outlet of the first kiln head is connected to a first dust collecting device.

[0068] In the present application, the first dust collecting device can suck material dust and the like into the device through negative pressure.

[0069] In one embodiment, the first dust collecting device is provided with a dust collecting port and a material discharge port, the dust collecting port of the first dust collecting device is connected to the dust discharge port of the first kiln head, and the material discharge port of the first dust collecting device is connected to the feed end of the first kiln body.

[0070] In the present application, the material in the first dust collecting device can be directly returned to the first kiln body, which will not affect the quality of the product after the first stage of sintering.

[0071] In one embodiment, at least two sintering temperature zones (for example, 2, 3, 4, 5, 6, 7, 8, 10 or 15, etc.) are provided in the second-stage hot kiln.

[0072] In one embodiment, the two-stage hot kiln includes a second kiln head and a second kiln body connected in sequence, the second kiln head is provided with a feed port, a discharge port and a dust outlet, the feed port of the second kiln head is connected to the discharge end of the first kiln body, the dust outlet of the second kiln head is connected to a second dust collecting device, and the discharge port of the second kiln head is connected to the feed end of the second kiln body.

[0073] In the present application, the second dust collecting device can suck material dust and the like into the device through negative pressure.

[0074] In one embodiment, the discharge end of the first kiln body is higher than the feed inlet of the second kiln head.

[0075] In one embodiment, the second dust collecting device is provided with a dust collecting port and a discharge port, the dust collecting port of the second dust collecting device is connected to the dust discharge port of the second kiln head, and the discharge port of the second dust collecting device is connected to the feed end of the second kiln body.

[0076] In the present application, the material in the second dust collecting device can be directly returned to the second kiln body, which will not affect the quality of the product after the second stage sintering.

[0077] In one embodiment, the discharge end of the second kiln body is connected to a cooling kiln.

[0078] In one embodiment, the kiln walls of the first and second kiln bodies are provided with lifting plates, which are used to lift materials and dust, ensuring the contact area between the materials and the kiln body, allowing the materials to be fully dispersed and heat exchanged in a timely manner, thereby improving the dehydration and desulfurization effect.

[0079] In one embodiment, the sintering system further comprises a filter press and a crusher. A conveyor is provided below the filter press to transport the water-containing filter cake to the crusher. The crusher is used for coarse crushing of the water-containing filter cake. After coarse crushing, the ferrous phosphate filter cake is directly conveyed to a first-stage hot kiln. The crusher only crushes the water-containing filter cake from the filter press and does not affect the product particles. The conveyor may include a conveyor belt, a vibrating conveyor, a belt conveyor, or other suitable conveying device.

[0080] In a third aspect, the present application provides a target product prepared by the sintering process described in the first aspect.

[0081] In one embodiment, the target product comprises iron phosphate and / or Co3O4.

[0082] In the present application, when the sulfur-containing component in the aqueous sulfur-containing material is sulfur-containing dihydrated ferric phosphate, the target product obtained by the sintering process is ferric phosphate. When the sulfur-containing component in the aqueous sulfur-containing material is sulfur-containing cobalt carbonate, sulfur-containing basic cobalt carbonate, and sulfur-containing cobalt hydroxide, the target product obtained by the sintering process is Co3O4.

[0083] In one embodiment, based on the total mass of the target product as 100%, the sulfur content in the target product is 0.01-0.05%, for example, 0.01%, 0.02%, 0.03%, 0.04% or 0.05%.

[0084] In a fourth aspect, the present application provides a positive electrode material, which is obtained by mixing and sintering the target product described in the third aspect and a lithium source.

[0085] In a fifth aspect, the present application provides a lithium-ion battery, wherein the positive electrode of the lithium-ion battery includes the positive electrode material described in the fourth aspect.

[0086] The system refers to an equipment system, a device system or a production device.

[0087] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to limited space and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0088] Compared with the prior art, the present invention has the following advantages:

[0089] The present application provides a sintering process, which firstly removes water from water-containing and sulfur-containing substances through n-stage sintering in a first-stage sintering process; then further removes sulfur through a second-stage sintering process to reduce the sulfur content in the target product; in addition, the first-stage sintering and the second-stage sintering process can also increase the BET surface area of ​​the target product, thereby improving product quality;

[0090] By adopting the sintering process of the present application, the traditional flash drying process can be omitted, production costs and energy consumption can be reduced, the production process can be simplified, production efficiency can be improved, and it is also beneficial to save energy and reduce environmental pollution. The flash drying process usually requires a large amount of thermal energy. Omitting this process can reduce energy consumption and carbon dioxide emissions; and in this sintering process, gaseous sulfides and water vapor do not contact the material at the same time, which can reduce condensation, reduce the generation of waste, improve production continuity, improve the purity and quality of the target product, reduce the impurity content, and make the product more in line with market demand and industry standards; in addition, the sintering process has a wide range of applications and can dehydrate and desulfurize a variety of water-containing and sulfur-containing substances.

[0091] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0093] FIG1 is a schematic diagram showing the connection relationship and structure of a first-stage hot kiln, a second-stage hot kiln, and a cold kiln provided in Example 1 of the present application;

[0094] FIG2 is a schematic diagram of the use process of the sintering system device provided in Example 1 of the present application;

[0095] FIG3 is a SEM image of a sintered product provided in Example 1 of the present application;

[0096] FIG4 is an XRD pattern of a sintered product provided in Example 1 of the present application;

[0097] FIG5 is a SEM image of the second-stage sintered product provided in Example 1 of the present application;

[0098] FIG6 is an XRD pattern of the two-stage sintering product provided in Example 1 of the present application;

[0099] Among them, 1-first stage hot kiln; 2-second stage hot kiln; 3-cold kiln; 4-first dust collecting device; 5-second dust collecting device. DETAILED DESCRIPTION

[0100] It should be understood that in the description of this application, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0101] It should be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0102] The technical solution of this application is further explained below through specific implementation methods.

[0103] Example 1

[0104] This embodiment provides a sintering system device for water-containing and sulfur-containing materials, which includes a filter press, a crushing device, and a first-stage hot kiln 1, a second-stage hot kiln 2, and a cold kiln 3 connected in sequence, as shown in FIG1 ;

[0105] A conveying device is provided below the filter press. The conveying device is a conveyor belt for conveying the filtered material to the crushing device. The crushing device is a crusher for coarsely crushing the filtered material. The coarsely crushed material is pushed into a hot kiln 1 by a screw.

[0106] The one-stage hot kiln 1 includes a first kiln head and a first kiln body connected in sequence. The first kiln head is provided with a feed port, a discharge port and a dust outlet. The feed port of the first kiln head is connected to a feed pipeline. The discharge port of the first kiln head is connected to the feed end of the first kiln body. The dust outlet of the first kiln head is connected to a first dust collecting device 4 (i.e., a dust collecting bin). The first dust collecting device 4 is provided with a dust collecting port and a discharge port. The dust collecting port of the first dust collecting device 4 is connected to the dust outlet of the first kiln head. The discharge port of the first dust collecting device 4 is connected to the feed end of the first kiln body. The first kiln body has an inclination angle of 2°, a copy plate is provided on its kiln wall, and 8 sintering constant temperature zones are provided in the first kiln body along the direction of material movement.

[0107] The two-stage hot kiln 2 includes a second kiln head and a second kiln body connected in sequence. The second kiln head is provided with a feed port, a discharge port and a dust outlet. The feed port of the second kiln head is connected to the discharge end of the first kiln body. The dust outlet of the second kiln head is connected to a second dust collecting device 5 (i.e., a dust collecting bin). The discharge port of the second kiln head is connected to the feed end of the second kiln body. The second kiln body has an inclination angle of 2°, a shovel is provided on its kiln wall, and eight sintering temperature zones are provided in the second kiln body along the direction of material movement.

[0108] The discharge end of the first kiln body is higher than the feed inlet of the second kiln head;

[0109] The second dust collecting device 5 is provided with a dust collecting port and a material discharging port. The dust collecting port of the second dust collecting device 5 is connected to the dust discharging port of the second kiln head, and the material discharging port of the second dust collecting device 5 is connected to the material feeding end of the second kiln body. The material discharging end of the second kiln body is connected to the cold kiln 3;

[0110] The use process of the sintering system device is shown in Figure 2. The water-containing and sulfur-containing material slurry first enters the filter press for filtration, and is then conveyed to the crushing device through the conveying device for crushing. After crushing, the material enters the first-stage hot kiln 1 for one-stage sintering. There is an exchange of water vapor containing the material and the material between the first-stage hot kiln 1 and the dust collecting bin connected to it. After the first stage of sintering, the material enters the second-stage hot kiln 2 for the second stage of sintering. There is an exchange of sulfide containing the material and the material between the second-stage hot kiln 2 and the dust collecting bin connected to it. After the second stage of sintering, the material enters the cold kiln for cooling. Among them, the crushing device, the first-stage hot kiln 1 and the dust collecting bin connected to it, the second-stage hot kiln 2 and the dust collecting bin connected to it and the cold kiln can be called a rotary kiln system.

[0111] This embodiment also provides a sintering process for a water-containing and sulfur-containing substance. The sintering process is performed in the above-mentioned sintering system device and includes the following steps:

[0112] (1) Slurry pretreatment: The sulfur-containing ferric phosphate dihydrate slurry is pumped into a filter press by a centrifugal pump for filtration and washing until the conductivity of the washing water reaches 254 μs / cm, and then discharged to the top of the belt conveyor;

[0113] (2) Coarse crushing: The filter cake with a free water content of 29.5% after filtration is transported to a crusher, and the crusher screw is used to preliminarily crush the dihydrate filter cake; at this time, the free water content of the sulfur-containing dihydrate ferric phosphate material is 29.5%, the sulfur content is 0.1477%, and the particle size D50 is 8.53 μm;

[0114] (3) Dehydration: The first stage hot kiln 1 contains 8 sintering constant temperature zones. The temperatures of each temperature zone are set to 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ and 450℃ in the direction of material movement. The coarsely crushed material is pushed into the first stage hot kiln 1 by a screw for one-stage sintering (i.e., 8-stage sintering). The placement time in each temperature zone is 0.15h. The water vapor and a small amount of material generated during the first stage sintering process are pumped into the dust collection bin through negative pressure. The material returns to the first stage hot kiln 1 through the discharge butterfly valve, and the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan. The SEM image and XRD pattern of the first stage sintering product are shown in Figures 3 and 4 respectively.

[0115] (4) Desulfurization: The second-stage hot kiln 2 contains 8 sintering constant temperature zones. The temperatures of each temperature zone are set to 550℃, 550℃, 600℃, 600℃, 650℃, 650℃, 700℃ and 700℃ in the direction of material movement. After the first-stage sintering, the powder is transported to the second-stage hot kiln 2 for the second-stage sintering (i.e., 8-stage sintering). The placement time in each temperature zone is 0.15h. The sulfide generated during the second-stage sintering process and a small amount of material are pumped into the dust collecting bin under negative pressure. Since there is no water vapor in the dust collecting bin, the sulfide will not react with the material to condense when it is cooled. The material returns to the second-stage hot kiln 2 through the dust collecting bin discharge butterfly valve, and the sulfide is pumped into the exhaust gas treatment system through the dehumidification fan; the SEM image and XRD pattern of the second-stage sintering product are shown in Figures 5 and 6 respectively;

[0116] (5) Discharge: After desulfurization, the anhydrous ferric phosphate is subjected to screening, demagnetization, packaging and other processes to obtain qualified ferric phosphate products.

[0117] Example 2

[0118] The sintering system provided in this embodiment is different from that in embodiment 1 only in that four sintering constant temperature zones are provided in the first stage hot kiln and six sintering temperature zones are provided in the second stage hot kiln.

[0119] The sintering process of the water-containing sulfur-containing material provided in this embodiment includes the following steps:

[0120] (1) Slurry pretreatment: The sulfur-containing ferric phosphate dihydrate slurry is pumped into a filter press by a centrifugal pump for filtration and washing until the conductivity of the washing water reaches 325 μs / cm, and then discharged to the top of the belt conveyor;

[0121] (2) Coarse crushing: The filter cake with a free water content of 28.5% after filtration is transported to a crusher, and the crusher screw is used to preliminarily crush the dihydrate filter cake; at this time, the free water content of the sulfur-containing dihydrate ferric phosphate material is 28.5%, the sulfur content is 0.1618%, and the particle size D50 is 10.51 μm;

[0122] (3) Dehydration: The first stage hot kiln contains four sintering constant temperature zones. The temperatures of each temperature zone are set to 150℃, 250℃, 350℃ and 450℃ in the direction of material movement. After coarse crushing, the material is pushed into the first stage hot kiln by a screw for one-stage sintering (i.e., four-stage sintering). The placement time in each temperature zone is 0.25h. The water vapor and a small amount of material generated during the first stage sintering process are pumped into the dust collection bin through negative pressure. The material returns to the first stage hot kiln through the discharge butterfly valve, and the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0123] (4) Desulfurization: The second-stage hot kiln contains 6 sintering constant temperature zones. The temperatures of each temperature zone are set to 550℃, 600℃, 650℃, 650℃, 700℃ and 700℃ in the direction of material movement. After the first-stage sintering, the powder is transported to the second-stage hot kiln for the second-stage sintering (i.e., 6-stage sintering). The placement time in each temperature zone is 0.20h. The sulfide generated during the second-stage sintering process and a small amount of material are pumped into the dust collection bin under negative pressure. Since there is no water vapor in the dust collection bin, the sulfide will not react with the material to condense when it is cooled. The material returns to the second-stage hot kiln through the dust collection bin discharge butterfly valve, and the sulfide is pumped into the exhaust gas treatment system through the dehumidification fan;

[0124] (5) Discharge: After desulfurization, the anhydrous ferric phosphate is subjected to screening, demagnetization, packaging and other processes to obtain qualified ferric phosphate products.

[0125] Example 3

[0126] The sintering system provided in this embodiment is different from that in embodiment 1 only in that six sintering constant temperature zones are provided in the first stage hot kiln and six sintering temperature zones are provided in the second stage hot kiln.

[0127] The sintering process of the water-containing sulfur-containing material provided in this embodiment includes the following steps:

[0128] (1) Slurry pretreatment: The sulfur-containing ferric phosphate dihydrate slurry is pumped into a filter press by a centrifugal pump for filtration and washing until the conductivity of the washing water reaches 441 μs / cm, and then discharged to the top of the belt conveyor;

[0129] (2) Coarse crushing: The filter cake with a moisture content of 29.3% after filtration is transported to a crusher, and the crusher screw is used to preliminarily crush the dihydrate filter cake; at this time, the free water content of the sulfur-containing dihydrate ferric phosphate material is 29.3%, the sulfur content is 0.1577%, and the particle size D50 is 9.31 μm;

[0130] (3) Dehydration: The first stage hot kiln contains 6 sintering constant temperature zones. The temperatures of each temperature zone are set to 150℃, 150℃, 250℃, 350℃, 400℃ and 450℃ in the direction of material movement. After coarse crushing, the material is pushed into the first stage hot kiln by a screw for sintering (i.e., 6-stage sintering). The placement time in each temperature zone is 0.20h. The water vapor and a small amount of material generated during the first stage sintering process are pumped into the dust collection bin through negative pressure. The material returns to the first stage hot kiln through the discharge butterfly valve, and the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0131] (4) Desulfurization: The second-stage hot kiln contains 6 sintering constant temperature zones. The temperatures of each temperature zone are set to 550℃, 600℃, 650℃, 650℃, 700℃ and 700℃ in the direction of material movement. After the first-stage sintering, the powder is transported to the second-stage hot kiln for the second-stage sintering (i.e., 6-stage sintering). The placement time in each temperature zone is 0.20h. The sulfide generated during the second-stage sintering process and a small amount of material are pumped into the dust collection bin under negative pressure. Since there is no water vapor in the dust collection bin, the sulfide will not react with the material to condense when it is cooled. The material returns to the second-stage hot kiln through the dust collection bin discharge butterfly valve, and the sulfide is pumped into the exhaust gas treatment system through the dehumidification fan;

[0132] (5) Discharge: After desulfurization, the anhydrous ferric phosphate is subjected to screening, demagnetization, packaging and other processes to obtain qualified ferric phosphate products.

[0133] Example 4

[0134] The sintering system provided in this embodiment is different from that in embodiment 1 only in that four sintering constant temperature zones are provided in the first stage hot kiln and four sintering temperature zones are provided in the second stage hot kiln.

[0135] The sintering process of the water-containing sulfur-containing material provided in this embodiment includes the following steps:

[0136] (1) Slurry pretreatment: The sulfur-containing ferric phosphate dihydrate slurry is pumped into a filter press by a centrifugal pump for filtration and washing until the conductivity of the washing water reaches 387 μs / cm, and then discharged to the top of the belt conveyor;

[0137] (2) Coarse crushing: The filter cake with a moisture content of 25.4% after filtration is transported to a crusher, and the crusher screw is used to preliminarily crush the dihydrate filter cake; at this time, the free water content of the sulfur-containing dihydrate ferric phosphate material is 25.4%, the sulfur content is 0.1674%, and the particle size D50 is 12.51 μm;

[0138] (3) Dehydration: The first stage hot kiln contains four sintering constant temperature zones. The temperatures of each temperature zone are set to 150℃, 250℃, 350℃ and 450℃ in the direction of material movement. After coarse crushing, the material is pushed into the first stage hot kiln by a screw for one-stage sintering (i.e., four-stage sintering). The placement time in each temperature zone is 0.25h. The water vapor and a small amount of material generated during the first stage sintering process are pumped into the dust collection bin through negative pressure. The material returns to the first stage hot kiln through the discharge butterfly valve, and the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0139] (4) Desulfurization: The two-stage hot kiln contains four sintering constant temperature zones. The temperatures of each temperature zone are set to 550℃, 600℃, 650℃ and 700℃ in the direction of material movement. After the first stage sintering, the powder is transported to the second stage hot kiln for the second stage sintering (i.e., four-stage sintering). The placement time in each temperature zone is 0.25h. The sulfide generated during the second stage sintering process and a small amount of material are pumped into the dust collection bin under negative pressure. Since there is no water vapor in the dust collection bin, the sulfide will not react with the material to condense when it is cooled. The material returns to the second stage hot kiln through the dust collection bin discharge butterfly valve, and the sulfide is pumped into the exhaust gas treatment system through the dehumidification fan;

[0140] (5) Discharge: After desulfurization, the anhydrous ferric phosphate is subjected to screening, demagnetization, packaging and other processes to obtain qualified ferric phosphate products.

[0141] Example 5

[0142] The difference between this embodiment and embodiment 1 is that, in the eight sintering constant temperature zones of the first-stage hot kiln, the temperatures of each zone are set to 300°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C and 450°C in sequence along the direction of material movement.

[0143] The rest remains the same as in Example 1.

[0144] Example 6

[0145] The difference between this embodiment and embodiment 1 is that step (3) and step (4) are respectively:

[0146] (3) The first stage hot kiln contains 8 sintering constant temperature zones. The temperatures of each zone are set to 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ and 450℃ in the direction of material movement. The coarsely crushed material is pushed into the first stage hot kiln by a screw for primary sintering, dehydration and desulfurization. The water vapor, sulfide and a small amount of material generated during the dehydration and desulfurization process are pumped into the dust collection bin under negative pressure. Some of the water vapor and sulfide condense when they come into contact with the material when cooled. The material returns to the first stage hot kiln through the discharge butterfly valve, while the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0147] (4) The temperature of each temperature zone in the second-stage hot kiln is set to 650℃. After the first-stage sintering, the powder is transported to the second-stage hot kiln, that is, from the second-stage hot kiln to the cold kiln.

[0148] The rest remains the same as in Example 1.

[0149] Comparative Example 1

[0150] The difference between this comparative example and Example 1 is that step (3) and step (4) are respectively:

[0151] (3) The first stage hot kiln contains 8 sintering constant temperature zones. The temperatures of each zone are set to 550℃, 550℃, 600℃, 600℃, 650℃, 650℃, 700℃ and 700℃ in the direction of material movement. The coarsely crushed material is pushed into the first stage hot kiln by a screw for primary sintering, dehydration and desulfurization. The water vapor, sulfide and a small amount of material generated during the dehydration and desulfurization process are pumped into the dust collection bin under negative pressure. Part of the water vapor and sulfide condenses when they come into contact with the material when cooled. The material returns to the first stage hot kiln through the discharge butterfly valve, while the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0152] (4) The temperature of each temperature zone in the second-stage hot kiln is set to 0℃. After the first-stage sintering, the powder is transported to the second-stage hot kiln and then to the cold kiln.

[0153] The rest remains the same as in Example 1.

[0154] Comparative Example 2

[0155] The difference between this comparative example and Example 1 is that step (3) and step (4) are respectively:

[0156] (3) The first stage hot kiln contains 8 sintering constant temperature zones. The temperatures of each zone are set to 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ and 450℃ in the direction of material movement. The coarsely crushed material is pushed into the first stage hot kiln by a screw for primary sintering, dehydration and desulfurization. The water vapor, sulfide and a small amount of material generated during the dehydration and desulfurization process are pumped into the dust collection bin under negative pressure. Some of the water vapor and sulfide condense when they come into contact with the material when cooled. The material returns to the first stage hot kiln through the discharge butterfly valve, while the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0157] (4) The temperature of each temperature zone in the second-stage hot kiln is set to 0℃. After the first-stage sintering, the powder is transported to the second-stage hot kiln and then to the cold kiln.

[0158] The rest remains the same as in Example 1.

[0159] Comparative Example 3

[0160] The difference between this comparative example and Example 1 is that step (3) and step (4) are respectively:

[0161] (3) The first stage hot kiln contains 8 sintering constant temperature zones, and the temperature of each zone is set at 700℃. After coarse crushing, the material is pushed into the first stage hot kiln by the screw for dehydration and desulfurization. The water vapor, sulfide and a small amount of material generated during the dehydration and desulfurization process are pumped into the dust collection bin under negative pressure. Some of the water vapor and sulfide condense when they come into contact with the material when cooled. The material returns to the first stage hot kiln through the discharge butterfly valve, while the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0162] (4) The temperature of each temperature zone in the second-stage hot kiln is set to 0℃. After the first-stage sintering, the powder is transported to the second-stage hot kiln and then to the cold kiln.

[0163] The rest remains the same as in Example 1.

[0164] Comparative Example 4

[0165] The difference between this comparative example and Example 1 is that step (3) and step (4) are respectively:

[0166] (3) The first stage hot kiln contains 8 sintering constant temperature zones, and the temperature of each zone is set at 700℃. After coarse crushing, the material is pushed into the first stage hot kiln by the screw for dehydration and desulfurization. The water vapor, sulfide and a small amount of material generated during the dehydration and desulfurization process are pumped into the dust collection bin under negative pressure. Some of the water vapor and sulfide condense when they come into contact with the material when cooled. The material returns to the first stage hot kiln through the discharge butterfly valve, while the water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0167] (4) The temperature of each temperature zone in the second-stage hot kiln is set to 700℃. After the first-stage sintering, the powder is transported to the second-stage hot kiln and then to the cold kiln.

[0168] The rest remains the same as in Example 1.

[0169] Comparative Example 5

[0170] The difference between this comparative example and Example 1 is that step (3) and step (4) are respectively:

[0171] (3) The first stage hot kiln contains 8 sintering constant temperature zones, and the temperature of each zone is set at 700℃. After coarse crushing, the material is pushed into the first stage hot kiln by the screw for dehydration and desulfurization. The water vapor, sulfide and a small amount of material generated during the dehydration and desulfurization process are pumped into the dust collection bin under negative pressure. The material in the dust collection bin will not return to the inside of the first stage hot kiln. The material is taken out separately through the discharge butterfly valve and will not be mixed with the production line material. The water vapor is pumped into the exhaust gas treatment system through the dehumidification fan;

[0172] (4) The temperature of each temperature zone in the second-stage hot kiln is set to 0℃. After the first-stage sintering, the powder is transported to the second-stage hot kiln and then to the cold kiln.

[0173] The rest remains the same as in Example 1.

[0174] Performance Testing

[0175] Test 1: The physical and chemical properties of the products obtained from Examples 1-6 and Comparative Examples 1-5 after passing through a single-stage kiln were tested. Specific elemental data were obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES). BET specific surface area, particle size D50, and tap density TD were measured using a surface area analyzer, a Malvern particle size analyzer, and a tap density analyzer, respectively. The test results are shown in Table 1, where the contents of S, H2O, Fe, and P are based on the total mass of the product obtained after passing through the single-stage kiln as 100%.

[0176] Table 1

[0177] As shown in Table 1, Examples 1-4 and 6 show that low-temperature sintering in a single hot kiln can remove the vast majority of moisture from the sulfur-containing ferric phosphate dihydrate material, but the S content is essentially unchanged. Comparative Examples 1-3 and 5 do not undergo a second-stage sintering, and in Comparative Example 4, neither the first-stage sintering nor the second-stage sintering is graded. The results of Comparative Examples 1-5 indicate that when the first-stage temperature is higher, the first-stage sintering can remove both S and moisture simultaneously, but the S removal rate is relatively low.

[0178] It can be seen from Examples 1 and 5 that if the temperature of the first temperature zone in a single-stage hot kiln is higher than that of the second temperature zone, the filter cake will agglomerate quickly during the dehydration process, affecting the dehydration process.

[0179] Test 2: The physical and chemical properties of the products obtained from Examples 1-6 and Comparative Examples 1-5 after passing through the second-stage hot kiln were tested. Specific elemental data were obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES). BET specific surface area, particle size D50, and tap density TD were measured using a surface area analyzer, a Malvern particle size analyzer, and a tap density analyzer, respectively. The test results are shown in Table 2, where the contents of S, H2O, Fe, and P are calculated based on the total mass of the product obtained after the second-stage hot kiln as 100%.

[0180] Table 2

[0181] As can be seen from Table 2, from Examples 1-4, it can be seen that after the low-temperature sintering in the first stage hot kiln removes most of the water, the second stage hot kiln performs desulfurization, which can effectively reduce the sulfur content in the product. As can be seen from Examples 1 and 6, compared with single-temperature desulfurization, setting a low-high temperature platform sintering in the second stage sintering has a better desulfurization effect, and the obtained product has a higher specific surface area; from the results of Example 1, Comparative Examples 1-3 and Comparative Example 5, it can be seen that Comparative Examples 1-3 are one-stage dehydration and desulfurization, condensation will occur, and the desulfurization effect is poor; Comparative Example 5 is a one-stage dehydration and desulfurization, and by taking out the material in the dust collection bin separately, the S content can be significantly reduced, but taking out the dust collection material separately causes material waste and increases processing costs. From the results of Example 1 and Comparative Example 4, it can be seen that if the first stage sintering does not adopt graded sintering, the first and second stage sintering are both single temperatures, and the desulfurization effect is poor. In addition, the results of Comparative Examples 1 and 3-5 show that the specific surface area of ​​their products is low.

[0182] It can be seen from Examples 1 and 5 that if the temperature of the first temperature zone in a single-stage hot kiln is higher than that of the second temperature zone, the filter cake will agglomerate rapidly during the dehydration process, affecting the subsequent desulfurization process and resulting in a higher sulfur content in the product.

[0183] Test 3: The iron phosphate finally provided by Examples 1-6 and Comparative Examples 1-5 was co-fired with lithium carbonate and glucose to prepare lithium iron phosphate positive electrode material, and lithium iron phosphate, conductive carbon black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone to prepare positive electrode slurry. After coating, the positive electrode sheet was obtained, and then graphite was used as the negative electrode, and assembled with a diaphragm and LiPF6 electrolyte to form a lithium-ion battery.

[0184] The compaction density of the lithium iron phosphate positive electrode material powder was tested by a powder compaction density meter; the following tests were carried out using an electrochemical workstation and other equipment: ① At room temperature of 25°C, the charge and discharge voltage was 2.0-3.65V and the charge and discharge rate was 0.1C to test the initial discharge capacity and initial coulombic efficiency; ② At room temperature of 25°C, the charge and discharge voltage was 2.0-3.65V and the charge and discharge rate was 1C to test the cycle performance for 200 weeks.

[0185] Table 3

[0186] As shown in Table 3, the precursors obtained in Examples 1-4 and 6 through two-stage dehydration and desulfurization sintering in this application have improved powder characteristics, which can increase the compaction density and discharge specific capacity of the synthesized lithium iron phosphate. Compared with Comparative Examples 1-5, it can be seen that the overall performance of the comparative examples, such as compaction performance and electrochemical performance, is poor.

[0187] It can be seen from Examples 1 and 5 that if the temperature of the first temperature zone in a single-stage hot kiln is higher than that of the second temperature zone, the lithium iron phosphate corresponding to the final sintered product will exhibit lower compaction density, capacity and coulombic efficiency.

Claims

1. A sintering process, comprising: Perform one-stage sintering on the water- and sulfur-containing substance to remove the first substance, and then perform two-stage sintering to remove the second substance to obtain the target product; Among them, the one-stage sintering is n-stage sintering, where n≥2 and n is an integer; The first substance includes water, and the second substance includes sulfur.

2. The sintering process according to claim 1, wherein, The water- and sulfur-containing substance includes free water and sulfur-containing components, and the sulfur-containing components include at least one of iron dihydrate phosphate containing sulfur, cobalt carbonate containing sulfur, basic cobalt carbonate containing sulfur, and cobalt hydroxide containing sulfur.

3. The sintering process according to claim 1 or 2, wherein, Based on the total mass of the water- and sulfur-containing substance being 100%, the mass content of the free water is less than 40%.

4. The sintering process according to any one of claims 1 - 3, wherein, Based on the total mass of the water- and sulfur-containing substance being 100%, the mass content of sulfur in the water- and sulfur-containing substance is 0.1 - 1.0%.

5. The sintering process according to any one of claims 2 - 4, wherein, The particle size D50 of the sulfur-containing component is 7 - 50 μm.

6. The sintering process according to any one of claims 1 - 5, wherein, The n-stage sintering includes the first-stage sintering, the second-stage sintering, and the x-stage sintering, where x≥3 and x is an integer; Optionally, the temperatures of the first-stage sintering and the second-stage sintering are independently 150 - 250°C; Optionally, the times of the first-stage sintering and the second-stage sintering are independently 0.05 - 0.50 h; Optionally, the temperature of the x-stage sintering is independently 200 - 500°C; Optionally, the time of the x-stage sintering is independently 0.05 - 0.50 h; Optionally, n satisfies the following condition: 4≤n≤8.

7. The sintering process according to any one of claims 1 - 6, wherein, The two-stage sintering is m-stage sintering, where m≥2 and m is an integer; Optionally, the m-stage sintering includes the first-stage sintering, the second-stage sintering, and the y-stage sintering, where y≥3 and y is an integer; Optionally, the temperatures of the first-stage sintering and the second-stage sintering are independently 550 - 750°C; Optionally, the times of the first-stage sintering and the second-stage sintering are independently 0.10 - 0.50 h; Optionally, the temperature of the y-stage sintering is independently 600 - 750°C; Optionally, the time of the y-stage sintering is independently 0.10 - 0.50 h; Optionally, m satisfies the following condition: 4≤m≤8.

8. The sintering process according to any one of claims 1 - 7, wherein, The sintering process specifically includes: Perform pressure filtration on the water- and sulfur-containing slurry, and after crushing, obtain the water- and sulfur-containing substance. The water- and sulfur-containing substance includes free water and sulfur-containing components, and the sulfur-containing components include at least one of iron dihydrate phosphate containing sulfur, cobalt carbonate containing sulfur, basic cobalt carbonate containing sulfur, and cobalt hydroxide containing sulfur; then perform one-stage sintering on the water- and sulfur-containing substance to remove water, and then perform two-stage sintering to remove sulfur and / or carbon dioxide to obtain the target product; Among them, the one-stage sintering is n-stage sintering, 4≤n≤8 and n is an integer; the n-stage sintering includes the first-stage sintering, the second-stage sintering, and the x-stage sintering, 3≤x≤8 and x is an integer. The temperatures of the first-stage sintering and the second-stage sintering are independently 150 - 250°C, and the temperature of the x-stage sintering is independently 200 - 500°C; The two-stage sintering is m-level sintering, where 4 ≤ m ≤ 8 and m is an integer; the m-level sintering includes first-stage sintering, second-stage sintering, and y-level sintering, where 3 ≤ y ≤ 8 and y is an integer. The temperatures of the first-stage sintering and the second-stage sintering are independently 550 - 750 °C, and the temperature of the y-level sintering is independently 600 - 750 °C.

9. A sintering system device for the sintering process according to any one of claims 1 - 8, comprising a first - stage hot kiln and a second - stage hot kiln connected in sequence, and at least 2 sintering constant - temperature zones are arranged in the first - stage hot kiln.

10. The sintering system device according to claim 9, wherein, The one-stage hot kiln includes a first kiln head and a first kiln body connected in sequence. The first kiln head is provided with a feed inlet, a discharge outlet, and a dust outlet. The feed inlet of the first kiln head is connected to a feed pipeline, the discharge outlet of the first kiln head is connected to the feed end of the first kiln body, and the dust outlet of the first kiln head is connected to a first dust collection device.

11. The sintering system device according to claim 10, wherein, The first dust collection device is provided with a dust collection inlet and a discharge outlet. The dust collection inlet of the first dust collection device is connected to the dust outlet of the first kiln head, and the discharge outlet of the first dust collection device is connected to the feed end of the first kiln body.

12. The sintering system device according to any one of claims 9-11, wherein, At least two sintering temperature zones are provided in the two-stage hot kiln.

13. The sintering system device according to any one of claims 9-12, wherein, The two-stage hot kiln includes a second kiln head and a second kiln body connected in sequence. The second kiln head is provided with a feed inlet, a discharge outlet, and a dust outlet. The feed inlet of the second kiln head is connected to the discharge end of the first kiln body, the dust outlet of the second kiln head is connected to a second dust collection device, and the discharge outlet of the second kiln head is connected to the feed end of the second kiln body.

14. The sintering system device according to claim 13, wherein, The second dust collection device is provided with a dust collection inlet and a discharge outlet. The dust collection inlet of the second dust collection device is connected to the dust outlet of the second kiln head, and the discharge outlet of the second dust collection device is connected to the feed end of the second kiln body.

15. A target product prepared by the sintering process according to any one of claims 1-8.

16. A cathode material obtained by mixing and sintering the target product according to claim 15 and a lithium source.

17. A lithium ion battery comprising the cathode material according to claim 9.

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