Method and system for preparing metal oxide precursor for battery by means of spray pyrolysis of nitrate

Abstract

The present invention relates to a method and system for preparing a metal oxide precursor for a battery by means of the spray pyrolysis of a nitrate. The method comprises: preparing a metal nitrate mixed solution; atomizing the metal nitrate mixed solution and spraying same into a reaction furnace, and then pyrolyzing same in different heating zones in the reaction furnace, so as to obtain a metal oxide mixture and high-temperature flue gas; subjecting the high-temperature flue gas to a waste heat recovery treatment, and then conveying same to a regeneration device for recovery, so as to obtain regenerated nitric acid; and subjecting the metal oxide mixture to secondary heating at the bottom of the reaction furnace. In the present invention, the metal oxide precursor is prepared by means of spray pyrolysis, and compared with a traditional coprecipitation and calcination process, the method is more economical and has lower operation costs; moreover, since different heating zones are used for pyrolysis, the method has a wider range of application, and can be used for metal nitrates having different pyrolysis temperatures.

Description

Method and system for preparing battery metal oxide precursor by spray pyrolysis of nitrate TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a method and system for preparing battery metal oxide precursor by spray pyrolysis of nitrate. BACKGROUND

[0002] At present, the new energy battery precursor on the market is generally composed of nickel, cobalt, manganese, iron, copper, zinc and other metal oxides, and the mainstream production process is co-precipitation calcination. The co-precipitation calcination method uses metal chloride salt, phosphate or sulfate salt, forms metal hydroxide precipitate by co-precipitation method, and generates metal oxide by calcination. The traditional co-precipitation method includes precipitation, filtration, drying and calcination, etc., involves many operation units, the manufacturing process is complex, a large amount of reagents, pure water and pure alkali are consumed during the preparation process, the output of waste water and sludge is large, and the operation cost is high. The high-temperature spray hydrolysis method for preparing the precursor usually uses chloride salt for high-temperature hydrolysis, and usually configures multi-metal chloride salt, then performs high-temperature spray hydrolysis, the generated hydrogen chloride is returned to the dissolution section by absorption, and the generated multi-metal oxide is used as a sodium battery precursor. However, due to the co-hydrolysis of the multi-metal chloride salt method, the oxide temperature zones generated by the reaction of various metals are different, it is difficult to realize co-hydrolysis, and due to the high reaction temperature required by the chloride salt method, the metal chloride salt reaction is not sufficient, the chloride residue is high, it is difficult to prepare the synthesized product, and further processes such as water washing, pressure filtration, drying and grinding are required, the process is complex, and the operation cost is high. Therefore, it is more urgent to develop a method for producing high-quality and low-cost new energy battery precursor material to break through the drawbacks of the existing precipitation calcination method and the chloride salt high-temperature spray pyrolysis method.

[0003] SUMMARY

[0004] In order to solve the above problems, on the one hand, the present application provides a method for preparing battery metal oxide precursor by spray pyrolysis of nitrate, comprising the following steps:

[0005] Preparation of a mixed solution of metal nitrates;

[0006] The mixed solution of metal nitrates is atomized and sprayed into the reaction furnace, and pyrolysis is carried out in different heating temperature zones in the reaction furnace to obtain a mixture of metal oxides and high-temperature flue gas;

[0007] The high-temperature flue gas is treated by waste heat recovery, and then enters the regeneration device to be recovered to obtain regenerated nitric acid;

[0008] The mixture of metal oxides is subjected to secondary heating at the bottom of the reaction furnace.

[0009] Furthermore, the metal nitrate mixed solution includes nickel nitrate solution, cobalt nitrate solution, and manganese nitrate solution, and also includes at least one of iron nitrate solution, copper nitrate solution, and zinc nitrate solution.

[0010] Furthermore, the heating temperature at the top of the reactor is 280–380°C, the heating temperature in the middle of the reactor is 550–1000°C, and the heating temperature at the bottom of the reactor is 360–550°C.

[0011] Furthermore, the total concentration of metal ions in the metal nitrate mixed solution is 100–180 g / L.

[0012] Furthermore, the metal nitrate mixed solution is concentrated before entering the reactor, and the total concentration of metal ions in the concentrated solution is 125-270 g / L.

[0013] Furthermore, the atomized spray droplet size D of the metal nitrate mixed solution... 32 The size ranges from 20 to 300 μm.

[0014] Furthermore, the particle size D of the oxide particles in the metal oxide mixture 50 The range is 0.5–75 μm.

[0015] Furthermore, the waste heat recovery treatment of the high-temperature flue gas includes exchanging heat between the high-temperature flue gas and a mixed solution of metal nitrates, and concentrating the mixed solution of metal nitrates.

[0016] Furthermore, the metal nitrate mixed solution is atomized and sprayed using one of the following methods: high-pressure liquefaction spraying, airflow dual-fluid spraying, and multi-fluid spraying.

[0017] On the other hand, the present invention also provides a system for preparing battery metal oxide precursors by nitrate spray pyrolysis, including a spray pyrolysis unit for reacting a mixed solution of metal nitrates and a recovery and purification unit for recovering high-temperature flue gas. The spray pyrolysis unit includes a reactor with multiple heating mechanisms. The recovery and purification unit includes a regeneration device connected to the flue gas outlet of the reactor.

[0018] By employing the above technical solutions, this invention has the following advantages compared to existing technologies:

[0019] 1) The method for preparing battery metal oxide precursors provided by the present invention uses spray pyrolysis to prepare metal oxide precursors, which is more economical and has lower operating costs than the traditional co-precipitation calcination process; and it uses different heating temperature zones for pyrolysis, which has a wider range of applications and can be used for metal nitrates with different pyrolysis temperatures.

[0020] 2) The method for preparing battery metal oxide precursor provided by the application can realize full recovery and utilization of heat energy and nitric acid resources, has remarkable economic benefits, is conducive to large-scale industrial production, and is energy-saving and environment-friendly, and has no waste residue and waste liquid discharge.

[0021] 3) The method for preparing battery metal oxide precursor provided by the application adopts metal nitrate as raw material, and has higher metal oxide purity and lower residual nitrate ion in the product, so that water washing operation is not needed in subsequent processing of the metal oxide, and the pure water consumption and operation cost can be greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Fig. 1 is a structural schematic diagram of a system for preparing battery metal oxide precursor by nitrate spray pyrolysis provided by the application;

[0024] Fig. 2 is a scanning electron microscope image of the metal oxide mixture in experimental example 3 of the application;

[0025] Fig. 3 is a scanning electron microscope image of the metal oxide mixture in experimental example 3 of the application;

[0026] Fig. 4 is a schematic diagram of the particle size distribution of the metal oxide mixture in experimental example 3 of the application.

[0027] a-spray pyrolysis unit; b-recovery and purification unit; c-oxide processing unit; 1-preparation device; 2-conveying device; 3-filtering device; 4-reaction furnace; 5-concentration device; 6-regeneration device; 7-washing device; 8-cooling device; 9-circulating device one; 10-oxidation synthesis device; 11-circulating device two; 12-heat exchanger; 13-catalytic reaction device; 14-oxide precursor processing device; 15-nitric acid storage device. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described in the description of the present application in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application. In the drawings, the size and relative size of a certain part may be exaggerated for clarity.

[0029] In the description of the present application, unless explicitly specified and limited, the terms "connection", "connection" should be interpreted broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium; it can be internal communication of two elements or interaction relationship between two elements, and those of ordinary skill in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0030] In the description of the present application, the terms "up", "down", "left", "right", "front", "back" and the like orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0031] In addition, in the description of the present application, the terms "first", "second" are only used to distinguish in description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. In addition, the features limited by "first", "second" can explicitly or implicitly include one or more features.

[0032] Embodiment 1

[0033] The present application provides a method for preparing battery metal oxide precursor by nitrate spray pyrolysis, comprising the following steps:

[0034] Preparation of metal nitrate mixed solution;

[0035] The metal nitrate mixed solution is atomized and sprayed into the reaction furnace 4, and pyrolysis is carried out in different heating temperature zones in the reaction furnace 4 to obtain a metal oxide mixture and high-temperature flue gas;

[0036] The high-temperature flue gas is treated by waste heat recovery, and then enters the regeneration device 6 to be recovered to obtain regenerated nitric acid;

[0037] The metal oxide mixture is subjected to secondary heating at the bottom of the reaction furnace 4.

[0038] Specifically, in the embodiment, the battery metal oxide precursor is prepared by nitrate spray pyrolysis. The prepared metal nitrate mixed solution is sent to the reaction furnace 4 in the form of atomized spray, and the reaction furnace 4 is preferably a spray pyrolysis reaction furnace. The reaction furnace 4 is provided with multiple heating temperature zones, and the metal nitrate is fully pyrolyzed in the corresponding heating temperature zone to obtain a metal oxide mixture and high-temperature flue gas containing nitrogen oxides (NO X ) and nitric acid gas. In the reaction furnace 4, the high-temperature flue gas is separated from the metal oxide mixture under the action of gravity and centrifugal force, and the metal oxide mixture falls into the bottom of the reaction furnace 4 for buffering and secondary heating reaction to eliminate residual nitrate ions in the metal oxide, so that the finally generated metal oxide does not contain residual nitrate ions. The high-temperature flue gas is discharged from the flue gas outlet of the reaction furnace 4, and after waste heat recovery, it enters the regeneration device 6. The nitric acid in the flue gas is absorbed by a certain concentration of nitric acid solution as an absorption liquid to form reusable regenerated nitric acid, which can be used to prepare a metal nitrate mixed solution.

[0039] Preferably, the metal nitrate mixed solution includes a nickel nitrate solution, a cobalt nitrate solution, and a manganese nitrate solution, and further includes at least one of an iron nitrate solution, a copper nitrate solution, and a zinc nitrate solution, that is, the metal nitrate mixed solution contains nickel, cobalt, and manganese elements, and further contains at least one of iron, copper, and zinc elements.

[0040] As one of the embodiments, the metal nitrate mixed solution is a nickel, cobalt, manganese, and iron metal nitrate mixed solution, and after spray pyrolysis in the reaction furnace, nickel, cobalt, manganese, and iron-based metal oxides are formed at the bottom of the reaction furnace.

[0041] As one of the embodiments, the metal nitrate mixed solution is a nickel, cobalt, manganese, and copper metal nitrate mixed solution, and after spray pyrolysis in the reaction furnace, nickel, cobalt, manganese, and copper-based metal oxides are formed at the bottom of the reaction furnace.

[0042] As one of the embodiments, the metal nitrate mixed solution is a nickel, cobalt, manganese, and zinc metal nitrate mixed solution, and after spray pyrolysis in the reaction furnace, nickel, cobalt, manganese, and zinc-based metal oxides are formed at the bottom of the reaction furnace.

[0043] As one of the embodiments, the metal nitrate mixed solution is a nickel, cobalt, manganese, iron, and copper metal nitrate mixed solution, or a nickel, cobalt, manganese, iron, and zinc metal nitrate mixed solution, or a nickel, cobalt, manganese, zinc, and copper metal nitrate mixed solution, or a nickel, cobalt, manganese, iron, copper, and zinc metal nitrate mixed solution.

[0044] In this embodiment, the mixed metal nitrate solution is a mixed solution of nickel, cobalt, manganese, iron, copper and zinc nitrate, wherein the molar percentage of each nitrate is 20-80% of Ni(NO3)2, 10-35% of Co(NO3)2, 10-45% of Mn(NO3)2, 10-33% of Fe(NO3)3, 10-20% of Cu(NO3)2, and 5-10% of Zn(NO3)2. The nitrate solution is atomized and sprayed into the reaction furnace for high-temperature hydrolysis, and the main reaction formula is: M(NO3)2+H2O→MO+2HNO3 2HNO3→NO2+NO+O+H2O NO2→NO+1 / 2O2

[0045] wherein M is a metal ion such as nickel, cobalt, manganese, iron, copper and zinc.

[0046] The pyrolysis temperatures of different metal nitrates are different, and in order to ensure that the multi-metal nitrates can be fully pyrolyzed, the reaction furnace 4 is provided with multiple heating temperature zones, the temperatures of different heating temperature zones are different, and the multiple heating temperature zones are realized by the heating devices in different regions of the reaction furnace 4. The nickel, cobalt, manganese, iron, copper and zinc metal nitrate solution undergoes thermal hydrolysis reaction in the corresponding temperature region to generate NO X nitrogen oxides and metal oxide precursors; by providing multiple heating temperature zones, the application range is wide, and the new energy battery precursor material preparation containing copper, zinc and other metal ions can be well adapted.

[0047] Preferably, the heating temperature at the top of the reaction furnace 4 is 280-380℃, the heating temperature at the middle of the reaction furnace 4 is 550-1000℃, and the heating temperature at the bottom of the reaction furnace 4 is 360-550℃, so as to satisfy the thermal hydrolysis of the mixed solution of nickel, cobalt, manganese, iron, copper and zinc nitrate. The heating temperature zones of the reaction furnace are controlled according to the hydrolysis temperatures of different metal ion nitrates, wherein the pyrolysis temperature of the Ni(NO3)2 solution is 260-350℃, the pyrolysis temperature of the Co(NO3)2 solution is 260-400℃, the pyrolysis temperature of the Mn(NO3)2 solution is 220-320℃, the pyrolysis temperature of the Fe(NO3)3 solution is 200-550℃, the pyrolysis temperature of the Cu(NO3)2 solution is 180-400℃, and the pyrolysis temperature of the Zn(NO3)2 solution is 220-350℃. Each nitrate solution is decomposed at the corresponding pyrolysis temperature, and the generated metal oxide is shaped at high temperature to obtain oxide particles. The temperature in the reaction furnace 4 is controlled and maintained by setting heating devices in different regions. One or more layers of heating devices are arranged on the reaction furnace to ensure that each metal nitrate solution is fully hydrolyzed to generate metal oxide precursors.

[0048] In an optimized embodiment, the metal nitrate mixed solution is configured by a certain proportion of nickel, cobalt, manganese, iron, copper and zinc metal nitrates, and the total concentration of metal ions in the mixed solution is 100-180 g / L. After the metal nitrate mixed solution is prepared, it is pressurized and sent into a spray pyrolysis reaction furnace, heated in a corresponding temperature zone, and pyrolysis of the nickel, cobalt, manganese, iron, copper and zinc metal nitrates is realized to generate a metal oxide mixture.

[0049] In one of the embodiments, the stock solution for producing a new energy battery precursor is configured by different metal nitrates, the solute is recovered nickel, cobalt, manganese, copper and zinc metal ion oxides and nitrates or waste battery recycling materials, etc., the solvent is a certain concentration of nitric acid solution and pure water, the solute is dissolved in the solvent to obtain a nitrate mixed solution with a total concentration of metal ions of 100-180 g / L.

[0050] In an optimized embodiment, the metal nitrate mixed solution is concentrated before entering the reaction furnace 4, and the total concentration of metal ions in the concentrated nitrate solution is 125-270 g / L. The concentrated metal nitrate mixed solution is in the form of stacked pressure atomization and is sprayed into the high-temperature pyrolysis reaction furnace 4 for high-temperature hydrolysis.

[0051] Preferably, the concentrated solution atomization spraying adopts high-pressure liquid spraying, gas flow double-fluid spraying or multi-fluid spraying, and the atomization spraying droplet particle size D 32 is 20-300 μm. In the embodiment, the gas flow double-fluid spraying is preferred, the spraying temperature is 85-98°C, the liquid pressure is 0.25-0.6 MPa, and the gas pressure is 0.3-0.6 MPa.

[0052] Specifically, the concentrated solution can be atomized and sprayed under the action of high-pressure gas, the metal nitrate mixed solution can form smaller droplets, the droplets can be fully dispersed in the reaction furnace, the pyrolysis efficiency is improved, and the nitrate pyrolysis is more sufficient.

[0053] The metal nitrate mixed solution can be concentrated by heat exchange with high-temperature flue gas. The high-temperature flue gas from the reaction furnace is heat-exchanged with the metal nitrate mixed solution, the metal nitrate mixed solution absorbs the heat of the high-temperature flue gas to evaporate and concentrate, and the metal nitrate mixed solution can be preheated before entering the reaction furnace 4 to reduce the heat consumption in the reaction furnace. The high-temperature flue gas is heat-recovered and then used in the next process. The waste heat of the high-temperature flue gas can be fully utilized, the heat energy and nitric acid resources can be fully recovered and utilized, the economic benefit is significant, and it is conducive to industrialized production.

[0054] Preferably, the metal nitrate mixed solution is pyrolyzed in the reaction furnace 4 to generate a metal oxide mixture, and the oxide particle size D 500.5-75 μm, and the metal oxide is subjected to secondary heating reaction at the bottom of the reaction furnace to eliminate residual nitrate ions in the metal oxide. The metal oxide particles are hollow spheres or agglomerated particles, have secondary grinding conditions, and the initial particle size is not greater than 1.5 μm.

[0055] In the optimized embodiment, after the high-temperature flue gas is heat-exchanged with the mixed solution of metal nitrates, the high-temperature flue gas enters the regeneration device 6, and the nitric acid in the high-temperature flue gas is absorbed by the nitric acid solution in the regeneration device 6. The residual nitrogen oxides in the flue gas that are not converted into nitric acid are subjected to washing and cooling, and then subjected to an oxidation reaction to generate nitric acid for enrichment, which can be delivered to the regeneration device 6 for absorption spraying. The residual nitrogen oxides that are not completely oxidized are subjected to heating and catalytic reduction reaction to generate N2, which is discharged in compliance with the standard.

[0056] The nickel, cobalt, manganese, iron, copper and zinc metal nitrate mixed solution is used for spray pyrolysis, and different heating temperature zones are used for pyrolysis. Each nitrate can be fully pyrolyzed, and the prepared battery precursor has higher quality. Under the condition of good system control, the metal oxide precursor does not need to be subjected to subsequent water washing operation, which can greatly reduce the pure water consumption and operating cost, and can realize no wastewater, waste residue and non-compliant waste gas emission.

[0057] The following is described by specific experimental examples:

[0058] Experimental Example 1

[0059] Nickel nitrate solution (Ni(NO3)2) with a nickel ion concentration of 120 g / L is atomized and sprayed into the reaction furnace 4. The top temperature of the reaction furnace is 280°C, the middle temperature of the reaction furnace is 800°C, and the bottom temperature of the reaction furnace is 420°C. The nickel nitrate solution is sprayed by gas-liquid two-fluid spraying, the spraying temperature is 90°C, the liquid pressure is 0.3 Mpa, and the gas pressure is 0.4 Mpa. The atomized spray droplet size D 32 is 80 μm. The nickel nitrate solution is pyrolyzed in the reaction furnace to obtain a nickel oxide precursor. The powder crystal size is 26.5 nm, the initial particle size is 0.35 μm, the agglomerated particle size is 1 μm, and the loose density is 0.45 g / cm 3 .

[0060] Nickel nitrate solution (Ni(NO3)2) with a nickel ion concentration of 130 g / L is atomized and sprayed into the reaction furnace 4. The top temperature of the reaction furnace is 280°C, the middle temperature of the reaction furnace is 800°C, and the bottom temperature of the reaction furnace is 420°C. The nickel nitrate solution is sprayed by gas-liquid two-fluid spraying, the spraying temperature is 90°C, the liquid pressure is 0.3 Mpa, and the gas pressure is 0.4 Mpa. The atomized spray droplet size D 32= 120 μm, the nickel nitrate solution is pyrolyzed in the reaction furnace to obtain a nickel oxide precursor, the powder crystal size is 27.0 nm, the initial particle size is 0.4 μm, the agglomerated particle size is 0.95 μm, and the loose density is 0.48 g / cm 3 .

[0061] Experimental Example 2

[0062] A cobalt ion concentration of 120 g / L cobalt nitrate solution (Co(NO3)2) is atomized and sprayed into the reaction furnace 4, the top temperature of the reaction furnace is 300°C, the middle temperature of the reaction furnace is 850°C, the bottom temperature of the reaction furnace is 450°C, the cobalt nitrate solution is sprayed by the gas-liquid two-fluid method, the spraying temperature is 85°C, the liquid pressure is 0.4 Mpa, the gas pressure is 0.5 Mpa, the atomized spray droplet size D 32 = 80 μm, the cobalt nitrate solution is pyrolyzed in the reaction furnace to obtain a cobalt oxide precursor, the powder crystal size is 24.5 nm, the initial particle size is 0.5 μm, the agglomerated particle size is 1.22 μm, and the loose density is 0.48 g / cm 3 .

[0063] A cobalt ion concentration of 130 g / L cobalt nitrate solution (Co(NO3)2) is atomized and sprayed into the reaction furnace 4, the top temperature of the reaction furnace is 300°C, the middle temperature of the reaction furnace is 850°C, the bottom temperature of the reaction furnace is 450°C, the cobalt nitrate solution is sprayed by the gas-liquid two-fluid method, the spraying temperature is 85°C, the liquid pressure is 0.4 Mpa, the gas pressure is 0.5 Mpa, the atomized spray droplet size D 32 = 120 μm, the cobalt nitrate solution is pyrolyzed in the reaction furnace to obtain a cobalt oxide precursor, the powder crystal size is 25.5 nm, the initial particle size is 0.5 μm, the agglomerated particle size is 0.68 μm, and the loose density is 0.52 g / cm 3 .

[0064] Experimental Example 3

[0065] A mixed solution of nickel, cobalt, manganese, iron, copper and zinc metal nitrate with a total metal ion concentration of 120 g / L is concentrated by high-temperature flue gas to a concentrated solution with a total metal ion concentration of 180 g / L, wherein the molar percentage of each nitrate is: Ni(NO3)2 is 40%, Co(NO3)2 is 14%, Mn(NO3)2 is 14%, Fe(NO3)3 is 14%, Cu(NO3)2 is 12%, and Zn(NO3)2 is 6%, the concentrated solution is atomized and sprayed into the reaction furnace, the top temperature of the reaction furnace is 280°C, the middle temperature of the reaction furnace is 800-850°C, the bottom temperature of the reaction furnace is 360°C, the concentrated solution is sprayed by the gas-liquid two-fluid method, the spraying temperature is 90°C, the liquid pressure is 0.6 Mpa, the gas pressure is 0.6 Mpa, and the atomized spray droplet size D32 The nitrate mixed solution is pyrolyzed in the reaction furnace to obtain an oxide mixture. As shown in Figs. 2 and 3 of the drawings, which are scanning electron microscope images of the oxide mixture at different magnifications, the oxide particles are hollow spheres and agglomerated particles, the powder crystal size is 24 nm, the initial particle size is 0.4 μm, the agglomerated particle size is 0.95 μm, and the loose density is 0.42 g / cm 3 As shown in Fig. 4 of the drawings, which is a schematic diagram of the particle size distribution of the oxide particles formed, curve x represents the particle size distribution curve, and curve y represents the cumulative particle size curve.

[0066] Example 2

[0067] As shown in Fig. 1 of the drawings, the application also provides a system for spray pyrolysis of nitrate to prepare a battery metal oxide precursor, which is used for the method for spray pyrolysis of nitrate to prepare a battery metal oxide precursor described in Example 1. The system comprises a spray pyrolysis unit a for reaction of a metal nitrate mixed solution and a recovery and purification unit b for high-temperature flue gas recovery. The spray pyrolysis unit a comprises a reaction furnace 4, and the reaction furnace 4 is provided with a plurality of heating mechanisms. The recovery and purification unit b comprises a regenerative device 6, and the regenerative device 6 is connected with a flue gas outlet of the reaction furnace 4. The metal nitrate mixed solution is pyrolyzed in the reaction furnace to generate high-temperature flue gas, which is treated in the recovery and purification unit b, and then discharged after reaching the standard.

[0068] Preferably, the spray pyrolysis unit a further comprises a configuration device 1, a conveying device 2, a filtering device 3, and a concentration device 5, the filtering device 3 is connected with the configuration device 1 through the conveying device 2, the configuration device 1 is used for the configuration of the mixed metal nitrate solution, a certain concentration of nitric acid is mixed with nickel, cobalt, manganese, copper, zinc, and other metal ion oxides, nitrates, or waste battery recycling materials, etc. to obtain a mixed metal nitrate solution with a total metal ion concentration of 100-180 g / L, the mixed metal nitrate solution is sent to the filtering device 3 after being pressurized by the conveying device 2, and after the filtering device separates the large particle solids and the undissolved residues, the mixed metal nitrate solution enters the concentration device 5 to exchange heat with the high-temperature flue gas from the reaction furnace 4, the mixed metal nitrate solution is concentrated to obtain a nitrate concentrate solution with a total metal ion concentration of 125-270 g / L, and the concentrate solution in the concentration device 5 is sent into the reaction furnace 4 after being pressurized by a superposition device, is atomized by the spray device of the reaction furnace 4, and reacts in different heating temperature zones in the reaction furnace, the nitrate solution slowly evaporates and gradually pyrolyzes in the corresponding heating temperature zone to generate high-temperature flue gas containing nitrogen oxides, nitric acid, etc. and a mixture of metal oxides. In the reaction furnace 4, the nickel, cobalt, manganese, iron, copper, and zinc metal nitrates are completely decomposed to generate one or more metal oxides of nickel, cobalt, manganese, iron, copper, and zinc, and the metal oxides are secondarily heated at the bottom of the reaction furnace to decompose the residual nitrate ions, and after the reaction is completed, the metal oxides enter the oxide precursor processing device 14 in the oxide processing unit c through the discharge valve at the bottom of the reaction furnace and the conveyor for next operation.

[0069] Preferably, the concentration device 5 is further connected with a concentrate solution circulation pipeline.

[0070] Preferably, the pyrolysis temperatures of different metal nitrates are different, the pyrolysis temperature of the Ni(NO3)2 solution is 260-350℃, the pyrolysis temperature of the Co(NO3)2 solution is 260-400℃, the pyrolysis temperature of the Mn(NO3)2 solution is 220-320℃, the pyrolysis temperature of the Fe(NO3)3 solution is 200-550℃, the pyrolysis temperature of the Cu(NO3)2 solution is 180-400℃, and the pyrolysis temperature of the Zn(NO3)2 solution is 220-350℃. In order to ensure the sufficient pyrolysis of each nitrate, the heating temperature at the top of the reaction furnace 4 is 280-380℃, the heating temperature in the middle of the reaction furnace 4 is 550-1000℃, and the heating temperature at the bottom of the reaction furnace 4 is 360-550℃.

[0071] Preferably, the recovery and purification unit b further comprises a washing device 7, a cooling device 8, an oxidation and synthesis device 10, a heat exchanger 12 and a catalytic reaction device 13 connected in sequence with the regeneration device 6. The high-temperature flue gas after pyrolysis in the reaction furnace 4 contains nitrogen oxides and nitric acid gas. In order to realize the recovery of nitrogen oxides and nitric acid gas generated in the reaction furnace 4, the high-temperature flue gas after waste heat recovery by the concentration device 5 enters the regeneration device 6, and is contacted with a nitric acid solution of a certain concentration to be absorbed, to obtain regenerated nitric acid, which is sent to a nitric acid storage device 15 for storage. The nitric acid in the nitric acid storage device 15 can be transported to a configuration device for configuring a metal nitrate solution. The nitric acid solution used for absorption in the regeneration device comes from a certain concentration of nitric acid solution returned from the washing device 7, the cooling device 8 and the oxidation and synthesis device 10.

[0072] The residual nitrogen oxides in the high-temperature flue gas which are not converted into nitric acid enter the washing device 7 for washing and the cooling device for cooling, and then enter the oxidation and synthesis device 10, where the nitrogen oxides are oxidized into nitric acid and enriched, and are returned to the regeneration device 6 by pressurization for spray absorption.

[0073] Preferably, the washing device 7 is connected with a washing circulation pipeline.

[0074] Preferably, the cooling device 8 is connected with a circulation device one for flue gas circulation and cooling.

[0075] Preferably, the oxidation and synthesis device 10 is connected with a circulation device two for nitric acid circulation.

[0076] Preferably, in order to realize the standard discharge of residual nitrogen oxides in the tail gas, the residual nitrogen oxide tail gas in the oxidation and synthesis device 10 enters the catalytic reaction device 13 after the heat exchanger 12, and is converted into N2 by catalytic reduction reaction at a reaction temperature of 280-420°C, and is discharged in a standard way.

[0077] In this embodiment, nickel, cobalt, manganese, iron, copper, zinc and other metal nitrates are used to prepare metal oxides by a spray pyrolysis method, and the pyrolysis is carried out in temperature zones in the reaction furnace. Compared with the traditional co-precipitation and calcination process, this method is more economical, has lower operation cost and is more widely applicable. Because the nitrate is completely decomposed, the prepared metal oxide has higher purity and lower residual nitrate ion. Under good control, the subsequent treatment of the metal oxide can not be water-washed, which can greatly reduce the consumption of pure water and the operation cost. After the high-temperature flue gas is absorbed and treated by the recovery and purification unit, nitric acid solution can be obtained, which can be reused. At the same time, the system also recovers the water medium in the configuration solution, which reduces the water consumption of the system. Under reasonable operation, no waste water, waste residue and non-standard waste gas are discharged, which is energy-saving and environmentally friendly, and is suitable for industrial large-scale production.

[0078] Those skilled in the art will appreciate that the application can be embodied in many other specific forms without departing from the spirit or essential characteristics thereof. Though the present application has been described in connection with particular embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations uses or adaptations of the application following in general the principles of the application and including such departures from the present disclosure as come within known or customary practice in the art to which the application pertains.

Claims

1. A method of producing battery metal oxide precursors by nitrate spray pyrolysis, characterized by, The method comprises the following steps: preparing a mixed metal nitrate solution; atomizing and spraying the mixed metal nitrate solution into a reaction furnace, pyrolyzing the solution in different heating temperature zones in the reaction furnace to obtain a mixed metal oxide and high-temperature flue gas; recovering waste heat from the high-temperature flue gas, and then recycling the flue gas in a regeneration device to obtain regenerated nitric acid; secondarily heating the mixed metal oxide in the bottom of the reaction furnace.

2. The method of claim 1, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The mixed metal nitrate solution comprises a nickel nitrate solution, a cobalt nitrate solution and a manganese nitrate solution, and further comprises at least one of an iron nitrate solution, a copper nitrate solution and a zinc nitrate solution.

3. The method of claim 1, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The heating temperature at the top of the reaction furnace is 280-380℃, the heating temperature in the middle of the reaction furnace is 550-1000℃, and the heating temperature at the bottom of the reaction furnace is 360-550℃.

4. The method of claim 1, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The total concentration of metal ions in the mixed metal nitrate solution is 100-180g / L.

5. The method of claim 4, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The mixed metal nitrate solution is concentrated before entering the reaction furnace, and the total concentration of metal ions in the concentrated solution is 125-270g / L.

6. The method of claim 1, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The atomized spray droplet size D of the mixed solution of metal nitrate is 20-300 μm. 32 is 20-300 μm.

7. The method of claim 1, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The particle size D of the oxide particles in the metal oxide mixture is 0.5 to 75 μm. 50 is 0.5 to 75 μm.

8. The method of claim 1, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The waste heat recovery of the high-temperature flue gas comprises heat exchanging the high-temperature flue gas with the mixed metal nitrate solution to concentrate the mixed metal nitrate solution.

9. The method of claim 1, wherein the nitrate salt is selected from the group consisting of ammonium nitrate, potassium nitrate, sodium nitrate, and mixtures thereof. The atomizing and spraying of the mixed metal nitrate solution is performed by using one of high-pressure liquid spraying, gas flow two-fluid spraying and multi-fluid spraying.

10. A system for producing battery metal oxide precursors by nitrate spray pyrolysis, characterized by, The method comprises a spray pyrolysis unit for the reaction of a mixed metal nitrate solution and a recovery and purification unit for the recovery of high-temperature flue gas, the spray pyrolysis unit comprises a reaction furnace provided with a plurality of heating mechanisms, and the recovery and purification unit comprises a regeneration device connected with a flue gas outlet of the reaction furnace.

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