Method and system for preparing battery metal oxide precursor through nitrate spray pyrolysis

Abstract

The invention relates to a method and a system for preparing a battery metal oxide precursor through nitrate spray pyrolysis. The method comprises the following steps: preparing a metal nitrate mixed solution; atomizing and spraying the metal nitrate mixed solution into a reaction furnace, and performing pyrolysis through different heating temperature zones in the reaction furnace to obtain a metal oxide mixture and high-temperature flue gas; the high-temperature flue gas is subjected to waste heat recovery treatment and then enters a regeneration device to be recovered, and regenerated nitric acid is obtained; the metal oxide mixture is subjected to secondary heating at the bottom of the reaction furnace. The metal oxide precursor is prepared through spray pyrolysis, and compared with a traditional coprecipitation calcination process, the method is more economical and lower in operation cost; and different heating temperature zones are adopted for pyrolysis, so that the application range is wider, and the device can be suitable for metal nitrate at different pyrolysis temperatures.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a method and system for preparing a battery metal oxide precursor by spray pyrolysis of nitrate. Background Art

[0002] At present, the precursors of new energy batteries on the market are generally composed of metal oxides such as nickel, cobalt, manganese, iron, copper, and zinc, and the mainstream production process is the co-precipitation calcination method. The co-precipitation calcination method uses metal chlorides, phosphates or sulfates to form metal hydroxide precipitates through co-precipitation, and then generates metal oxides through calcination. The traditional co-precipitation method includes precipitation, filtration, drying and calcination, etc., involving many operating units and complex manufacturing processes. A large amount of reagents, pure water and soda ash are consumed during the preparation process, and the output of wastewater and sludge is large, and the operating costs remain high. The high-temperature spray hydrolysis method usually uses chloride salts for high-temperature hydrolysis to prepare precursors. Usually, multi-metal chloride salts are prepared first, and then high-temperature spray hydrolysis is carried out. The generated hydrogen chloride is returned to the dissolution stage through absorption, and the generated multi-metal oxides are used as sodium battery precursors. However, due to the co-hydrolysis of multiple metals in the chloride method, the temperature zones of the various metal reactions to produce oxides are different, making it difficult to achieve co-hydrolysis. In addition, due to the high reaction temperature required for the chloride method, the metal chloride salts do not react fully, and there are many chloride residues, making it difficult to prepare synthetic products. Further washing, filter pressing, drying, grinding and other processes are required, which are complex and have high operating costs. Therefore, it has become more urgent to break through the shortcomings of the existing precipitation calcination method and the chloride salt high-temperature spray pyrolysis method and develop a method that can produce high-quality and low-cost new energy battery precursor materials. Summary of the invention

[0003] In order to solve the above problems, on the one hand, the present invention provides a method for preparing a battery metal oxide precursor by spray pyrolysis of nitrate, comprising the following steps:

[0004] preparing a metal nitrate mixed solution;

[0005] The metal nitrate mixed solution is atomized and sprayed into a reaction furnace, and pyrolyzed in different heating temperature zones in the reaction furnace to obtain a metal oxide mixture and high-temperature flue gas;

[0006] The high-temperature flue gas is treated by waste heat recovery and then enters a regeneration device for recovery to obtain regenerated nitric acid;

[0007] The metal oxide mixture is secondary heated at the bottom of the reaction furnace.

[0008] Furthermore, the metal nitrate mixed solution includes a nickel nitrate solution, a cobalt nitrate solution and a manganese nitrate solution, and also includes at least one of an iron nitrate solution, a copper nitrate solution and a zinc nitrate solution.

[0009] Furthermore, the heating temperature of the top of the reaction furnace is 280-380°C, the heating temperature of the middle of the reaction furnace is 550-1000°C, and the heating temperature of the bottom of the reaction furnace is 360-550°C.

[0010] Furthermore, the total concentration of metal ions contained in the metal nitrate mixed solution is 100-180 g / L.

[0011] Furthermore, the metal nitrate mixed solution is concentrated before entering the reaction furnace, and the total concentration of metal ions contained in the concentrated solution is 125-270 g / L.

[0012] Furthermore, the atomized spray droplet size D of the metal nitrate mixed solution is 32 20~300μm.

[0013] Furthermore, the particle size D of the oxide particles in the metal oxide mixture is 50 0.5~75μm.

[0014] Furthermore, the waste heat recovery treatment of the high-temperature flue gas includes heat exchanging the high-temperature flue gas with a metal nitrate mixed solution to concentrate the metal nitrate mixed solution.

[0015] Furthermore, the atomization spraying of the metal nitrate mixed solution adopts one of high-pressure liquefaction spraying, airflow double-fluid spraying and multi-fluid spraying.

[0016] On the other hand, the present invention also provides a system for preparing battery metal oxide precursors by spray pyrolysis of nitrates, including a spray pyrolysis unit for reacting a metal nitrate mixed solution and a recovery and purification unit for recovering high-temperature flue gas, wherein the spray pyrolysis unit includes a reaction furnace provided with a plurality of heating mechanisms, and the recovery and purification unit includes a regeneration device connected to the flue gas outlet of the reaction furnace.

[0017] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0018] 1) The method for preparing a metal oxide precursor for a battery provided by the present invention adopts spray pyrolysis to prepare the metal oxide precursor, which is more economical and has lower operating costs than the traditional co-precipitation calcination process; and different heating temperature zones are used for pyrolysis, which has a wider application range and can be applied to metal nitrates with different pyrolysis temperatures.

[0019] 2) The method for preparing a metal oxide precursor for a battery provided by the present invention recovers waste heat from high-temperature flue gas and obtains regenerated nitric acid through a regeneration device. The process is energy-saving and environmentally friendly, and no waste residue or waste liquid is discharged. It can fully recycle resources such as heat energy and nitric acid, has significant economic benefits, and is conducive to industrial large-scale production.

[0020] 3) The method for preparing a battery metal oxide precursor provided by the present invention uses metal nitrate as a raw material. Because of its thorough decomposition, the prepared metal oxide has a higher purity, the residual nitrate ion in the product is lower, and the subsequent treatment of the metal oxide does not require water washing, which can greatly reduce the consumption of pure water and significantly reduce the operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a system for preparing a battery metal oxide precursor by spray pyrolysis of nitrate provided by the present invention;

[0023] Figure 2 The scanning electron microscope of the metal oxide mixture in Experimental Example 3 of the present invention Figure 1 ;

[0024] Figure 3 The scanning electron microscope of the metal oxide mixture in Experimental Example 3 of the present invention Figure 2 ;

[0025] Figure 4 Schematic diagram of particle size distribution of the metal oxide mixture in Experimental Example 3 of the present invention.

[0026] 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-circulation device 1; 10-oxidation synthesis device; 11-circulation device 2; 12-heat exchanger; 13-catalytic reaction device; 14-oxide precursor processing device; 15-nitric acid storage device. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the drawings, the size and relative size of some parts may be enlarged for clarity.

[0028] In the description of the present invention, unless otherwise clearly stipulated and limited, the terms "connection" and "connected" should be interpreted in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the description of the present invention, terms such as "up", "down", "left", "right", "front", "back", etc., and the 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, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0030] In addition, in the description of the present invention, the terms "first" and "second" are only used to distinguish in the 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 defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0031] Example 1

[0032] The present invention provides a method for preparing a battery metal oxide precursor by spray pyrolysis of nitrate, comprising the following steps:

[0033] preparing a metal nitrate mixed solution;

[0034] The metal nitrate mixed solution is atomized and sprayed into the reaction furnace 4, and pyrolyzed in different heating temperature zones in the reaction furnace 4 to obtain a metal oxide mixture and high-temperature flue gas;

[0035] The high-temperature flue gas is treated by waste heat recovery and then enters the regeneration device 6 for recovery to obtain regenerated nitric acid;

[0036] The metal oxide mixture is heated for a second time at the bottom of the reaction furnace 4 .

[0037] Specifically, in this embodiment, nitrate spray pyrolysis is used to prepare the battery metal oxide precursor, and the prepared metal nitrate mixed solution is sent to the reactor 4 by atomization spraying. The reactor 4 is preferably a spray pyrolysis reactor; the reactor 4 is provided with a plurality of heating temperature zones, and the metal nitrate is fully pyrolyzed in the corresponding heating temperature zones to obtain a metal oxide mixture and high-temperature flue gas, wherein the high-temperature flue gas contains nitrogen oxides (NO X ) and nitric acid gas, in the reactor 4, under the action of gravity and centrifugal force, the high-temperature flue gas and the metal oxide mixture are separated, and the metal oxide mixture falls into the bottom of the reactor 4 for buffering and secondary heating reaction to eliminate the residual nitrate ions in the metal oxides, so that no nitrate ions remain in the finally generated metal oxides; the high-temperature flue gas is discharged from the flue gas outlet of the reactor 4, and after the waste heat is recovered, it enters the regeneration device 6, and a nitric acid solution of a certain concentration is used as an absorption liquid to absorb the nitric acid in the flue gas to form reusable regenerated nitric acid, which can be used to prepare a metal nitrate mixed solution.

[0038] Preferably, 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, that is, the metal nitrate mixed solution contains nickel, cobalt, manganese elements, and also contains at least one of iron, copper and zinc elements.

[0039] As one of the implementation modes, the metal nitrate mixed solution is a nickel, cobalt, manganese and iron metal nitrate mixed solution, which is spray-pyrolyzed in a reaction furnace to form metal oxides mainly composed of nickel, cobalt, manganese and iron at the bottom of the reaction furnace.

[0040] As one of the implementation modes, the metal nitrate mixed solution is a nickel, cobalt, manganese and copper metal nitrate mixed solution, which forms metal oxides mainly composed of nickel, cobalt, manganese and copper at the bottom of the reactor after spray pyrolysis in the reactor.

[0041] As one of the implementation modes, the metal nitrate mixed solution is a nickel, cobalt, manganese and zinc metal nitrate mixed solution, which is spray-pyrolyzed in a reaction furnace to form metal oxides mainly composed of nickel, cobalt, manganese and zinc at the bottom of the reaction furnace.

[0042] As one of the embodiments, the metal nitrate mixed solution is a mixed solution of nickel, cobalt, manganese, iron and copper metal nitrates, or a mixed solution of nickel, cobalt, manganese, iron and zinc metal nitrates, or a mixed solution of nickel, cobalt, manganese, zinc and copper metal nitrates, or a mixed solution of nickel, cobalt, manganese, iron, copper and zinc metal nitrates.

[0043] In this embodiment, the metal nitrate mixed solution is a mixed solution of nickel, cobalt, manganese, iron, copper and zinc metal nitrates, wherein the molar percentage of each nitrate is 20% to 80% for Ni(NO3)2, 10% to 35% for Co(NO3)2, 10% to 45% for Mn(NO3)2, 10% to 33% for Fe(NO3)3, 10% to 20% for Cu(NO3)2 and 5% to 10% for Zn(NO3)2. The nitrate solution is sprayed into the reactor for high temperature hydrolysis, and the main reaction formula is:

[0044] M(NO3)2+H2O→MO+2HNO3

[0045] 2HNO3→NO2+NO+O+H2O

[0046] NO2→NO+1 / 2O2

[0047] Wherein, M is a metal ion such as nickel, cobalt, manganese, iron, copper, zinc, etc.

[0048] Different metal nitrates have different pyrolysis temperatures. To ensure that the multi-metal nitrates can be fully pyrolyzed, the reactor 4 is provided with multiple heating temperature zones. The temperatures of different heating temperature zones are different. The heating devices in different areas of the reactor 4 are used to achieve the setting of multiple heating temperature zones. The nickel, cobalt, manganese, iron, copper, and zinc metal nitrate solutions undergo thermal hydrolysis reactions in the corresponding temperature zones to generate NO. X Nitrogen oxide and metal oxide precursors; by setting multiple heating temperature zones, it has a wide range of applications and can better adapt to the preparation of new energy battery precursor materials containing metal ions such as copper and zinc.

[0049] Preferably, the heating temperature of the top of the reactor 4 is 280-380°C, the heating temperature of the middle of the reactor 4 is 550-1000°C, and the heating temperature of the bottom of the reactor 4 is 360-550°C, so as to meet the thermal hydrolysis of the mixed solution of nickel, cobalt, manganese, iron, copper and zinc metal nitrates. The heating temperature zone of the reactor is controlled according to the hydrolysis temperature of the nitrates of different metal ions, wherein the thermal decomposition temperature of Ni(NO3)2 solution is 260-350°C; Co(NO3) 2 solution pyrolysis temperature is 260℃~400℃; Mn(NO3)2 solution pyrolysis temperature is 220℃~320℃; Fe(NO3)3 solution pyrolysis temperature is 200℃~550℃; Cu(NO3)2 solution pyrolysis temperature is 180~400℃; Zn(NO3)2 solution pyrolysis temperature is 220~350℃, each nitrate solution is decomposed at its corresponding pyrolysis temperature, and the generated metal oxide is formed at high temperature to obtain oxide particles. The temperature in the reactor 4 is controlled and maintained by arranging heating devices in different areas. On the reactor, one or more layers of heating devices are arranged to ensure that each metal nitrate solution is fully hydrolyzed to generate metal oxide precursors.

[0050] In an optimized implementation method, the metal nitrate mixed solution is composed of a certain proportion of nickel, cobalt, manganese, iron, copper and zinc metal nitrates, and the total concentration of metal ions contained 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 reactor, and heated in a corresponding temperature zone to achieve pyrolysis of nickel, cobalt, manganese, iron, copper and zinc metal nitrates to generate a metal oxide mixture.

[0051] As one of the implementation methods, the raw solution for producing new energy battery precursors is prepared from different metal nitrates, the solute is recovered nickel, cobalt, manganese, copper, zinc metal ion oxides and nitrates or recycled materials from waste batteries, and the solvent is a nitric acid solution and pure water of a certain concentration. The solute is dissolved in the solvent to obtain a nitrate mixed solution with a total metal ion concentration of 100 to 180 g / L.

[0052] In an optimized implementation method, the metal nitrate mixed solution is concentrated before entering the reactor 4. After high-temperature concentration, the total concentration of metal ions contained in the nitrate concentrate is 125-270 g / L. The concentrated metal nitrate mixed solution enters the high-temperature pyrolysis reactor 4 in a superimposed atomization spray form for high-temperature hydrolysis.

[0053] Preferably, the concentrated liquid atomization spray adopts high-pressure liquefaction spray, airflow double-fluid spray or multi-fluid spray, and the atomization spray droplet particle size D 32It is 20-300 μm. In this embodiment, airflow dual-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.

[0054] Specifically, the concentrated solution can be atomized and sprayed under the action of high-pressure gas, and the metal nitrate mixed solution can form droplets with smaller particle size. The droplets can be fully dispersed in the reaction furnace, thereby improving the pyrolysis efficiency and making the nitrate pyrolysis more complete.

[0055] The metal nitrate mixed solution can be concentrated by heat exchange with the high-temperature flue gas. The high-temperature flue gas coming out of 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. It can also be preheated before entering the reaction furnace 4 to reduce the heat consumption in the reaction furnace. The high-temperature flue gas is recovered by waste heat before the next process. The waste heat of the high-temperature flue gas can be fully utilized to achieve full recovery and utilization of thermal energy, nitric acid and other resources. The economic benefit is significant and is conducive to industrial-scale production.

[0056] Preferably, the metal nitrate mixed solution is pyrolyzed in the reaction furnace 4 to generate a metal oxide mixture, the oxide particle size D 50 The metal oxide is 0.5-75 μm, and the metal oxide undergoes secondary heating reaction at the bottom of the reactor to eliminate the residual nitrate ions in the metal oxide. The metal oxide particles are hollow spheres and agglomerated particles, which have secondary grinding conditions, and the initial particle size is not greater than 1.5 μm.

[0057] In an optimized implementation method, the high-temperature flue gas enters the regeneration device 6 after heat exchange with the metal nitrate mixed solution, 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 have not been converted into nitric acid are washed and cooled, and then oxidized to generate nitric acid for enrichment, which can be transported to the regeneration device 6 for absorption spraying; the residual nitrogen oxides that are completely oxidized are heated and catalytically reduced to generate N2, and the emission meets the standards.

[0058] A mixed solution of nickel, cobalt, manganese, iron, copper and zinc metal nitrates 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 good system control, the metal oxide precursor does not need to be washed subsequently, which can greatly reduce the consumption of pure water and the operating cost, and can achieve zero wastewater, waste residue and substandard exhaust gas emissions.

[0059] The following is an explanation with a specific experimental example:

[0060] Experimental Example 1

[0061] A nickel nitrate solution (Ni(NO3)2) with a nickel ion concentration of 120 g / L is sprayed into the reactor 4. The temperature of the reactor top is 280°C, the temperature of the middle of the reactor is 800°C, and the temperature of the bottom of the reactor is 420°C. The nickel nitrate solution is sprayed with air flow double fluid. The spray temperature is 90°C, the liquid pressure is 0.3 MPa, the gas pressure is 0.4 MPa, and the atomized spray droplet size D 32 The nickel nitrate solution is pyrolyzed in the reaction furnace to obtain a nickel oxide precursor with a powder crystal size of 26.5nm, an initial particle size of 0.35μm, an agglomerated particle size of 1μm, and a loose density of 0.45g / cm 3 .

[0062] A nickel nitrate solution (Ni(NO3)2) with a nickel ion concentration of 130 g / L is sprayed into the reactor 4. The temperature of the reactor top is 280°C, the temperature of the middle of the reactor is 800°C, and the temperature of the bottom of the reactor is 420°C. The nickel nitrate solution is sprayed by air flow double fluid. The spray temperature is 90°C, the liquid pressure is 0.3 MPa, the gas pressure is 0.4 MPa, and the atomized spray droplet size D 32 The nickel nitrate solution was pyrolyzed in the reaction furnace to obtain a nickel oxide precursor with a powder crystal size of 27.0 nm, an initial particle size of 0.4 μm, an agglomerated particle size of 0.95 μm, and a loose density of 0.48 g / cm 3 .

[0063] Experimental Example 2

[0064] A cobalt nitrate solution (Co(NO3)2) with a cobalt ion concentration of 120 g / L is sprayed into the reactor 4. The temperature of the reactor top is 300°C, the temperature of the middle of the reactor is 850°C, and the temperature of the bottom of the reactor is 450°C. The cobalt nitrate solution is sprayed with air flow double fluid. The spray temperature is 85°C, the liquid pressure is 0.4 MPa, the gas pressure is 0.5 MPa, and the atomized spray droplet size D 32 The cobalt nitrate solution was pyrolyzed in the reaction furnace to obtain a cobalt oxide precursor with a powder crystal size of 24.5nm, an initial particle size of 0.5μm, an agglomerated particle size of 1.22μm, and a loose density of 0.48g / cm 3 .

[0065] A cobalt nitrate solution (Co(NO3)2) with a cobalt ion concentration of 130 g / L is sprayed into the reactor 4. The temperature of the reactor top is 300°C, the temperature of the middle of the reactor is 850°C, and the temperature of the bottom of the reactor is 450°C. The cobalt nitrate solution is sprayed with air flow double fluid. The spray temperature is 85°C, the liquid pressure is 0.4 MPa, the gas pressure is 0.5 MPa, and the atomized spray droplet size D 32The cobalt nitrate solution was pyrolyzed in the reactor to obtain a cobalt oxide precursor with a powder crystal size of 25.5nm, an initial particle size of 0.5μm, an agglomerated particle size of 0.68μm, and a loose density of 0.52g / cm 3 .

[0066] Experimental Example 3

[0067] A mixed solution of nickel, cobalt, manganese, iron, copper and zinc nitrates 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 40% for Ni(NO3)2, 14% for Co(NO3)2, 14% for Mn(NO3)2, 14% for Fe(NO3)3, 12% for Cu(NO3)2 and 6% for Zn(NO3)2. The solution is sprayed into a reactor in an atomized manner. The temperature of the reactor top is 280°C, the temperature of the middle part is 800-850°C and the temperature of the bottom part is 360°C. The concentrated solution is sprayed by airflow double fluid. The spraying temperature is 90°C, the liquid pressure is 0.6Mpa, the gas pressure is 0.6Mpa, and the atomized spray droplet size D 32 The nitrate mixed solution is pyrolyzed in the reaction furnace to obtain an oxide mixture, as shown in the attached manual. Figure 2 and 3 The following 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 the instruction manual Figure 4 , which is a schematic diagram of the particle size distribution of the formed oxide particles, wherein curve x represents the particle size distribution curve, and curve y represents the particle size cumulative curve.

[0068] Example 2

[0069] As the instruction manual Figure 1 As shown, the present invention also provides a system for preparing battery metal oxide precursors by spray pyrolysis of nitrates, which is used in the method for preparing battery metal oxide precursors by spray pyrolysis of nitrates described in Example 1, and the system includes a spray pyrolysis unit a for the reaction of a metal nitrate mixed solution and a recovery and purification unit b for recovering high-temperature flue gas, the spray pyrolysis unit a includes a reactor 4, and the reactor 4 is provided with a plurality of heating mechanisms, and the recovery and purification unit b includes a regeneration device 6, and the regeneration device 6 is connected to the flue gas outlet of the reactor 4. The metal nitrate mixed solution is pyrolyzed in the reactor, and the high-temperature flue gas generated enters the recovery and purification unit for treatment and is discharged after reaching the standard.

[0070] Preferably, the spray pyrolysis unit a further comprises a configuration device 1, a conveying device 2, a filtering device 3 and a concentrating device 5, wherein the filtering device 3 is connected to the configuration device 1 via the conveying device 2, and the configuration device 1 is used for the configuration of a metal nitrate mixed solution, wherein a certain concentration of nitric acid is dissolved and mixed with metal ion oxides, nitrates or waste battery recycling materials such as nickel, cobalt, manganese, copper and zinc in the configuration device to obtain a metal nitrate mixed solution with a total metal ion concentration of 100 to 180 g / L, and the metal nitrate mixed solution is pressurized by the conveying device 2 and sent to the filtering device 3, and the large nitrates are separated by the filtering device. After the granular solid and the undissolved residue, the metal nitrate mixed solution enters the concentration device 5, and heat exchanges with the high-temperature flue gas coming out of the reaction furnace 4. The metal nitrate mixed solution is concentrated to obtain a nitrate concentrate with a total metal ion concentration of 125-270 g / L. The concentrate in the concentration device 5 is pressurized by the superposition device and sent to the reaction furnace 4. It is sprayed 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, 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. The metal oxides are heated again at the bottom of the reaction furnace to decompose the residual nitrate ions therein. After the reaction is completed, the metal oxides enter the oxide precursor treatment device 14 in the oxide treatment unit c through the unloading valve and conveyor at the bottom of the furnace for the next operation.

[0071] Preferably, the concentrating device 5 is also connected to a concentrated liquid circulation pipeline.

[0072] Preferably, different metal nitrates have different pyrolysis temperatures, the pyrolysis temperature of Ni(NO3)2 solution is 260℃~350℃; the pyrolysis temperature of Co(NO3)2 solution is 260℃~400℃; the pyrolysis temperature of Mn(NO3)2 solution is 220℃~320℃; the pyrolysis temperature of Fe(NO3)3 solution is 200℃~550℃; the pyrolysis temperature of Cu(NO3)2 solution is 180~400℃; the pyrolysis temperature of Zn(NO3)2 solution is 220~350℃; to ensure sufficient pyrolysis of each nitrate, the heating temperature of the top of the reactor 4 is 280~380℃, the heating temperature of the middle of the reactor 4 is 550~1000℃, and the heating temperature of the bottom of the reactor 4 is 360~550℃.

[0073] Preferably, the recovery and purification unit b further comprises a washing device 7, a cooling device 8, an oxidation synthesis device 10, a heat exchanger 12 and a catalytic reaction device 13 connected in sequence to the regeneration device 6. The high-temperature flue gas after pyrolysis in the reactor 4 contains nitrogen oxides and nitric acid gas. In order to realize the recovery of nitrogen oxides and nitric acid gas generated in the reactor 4, the high-temperature flue gas after waste heat recovery by the concentrator 5 enters the regeneration device 6, contacts and absorbs with a certain concentration of nitric acid solution, obtains regenerated nitric acid, and is sent to the nitric acid storage device 15 for storage and standby. The nitric acid in the nitric acid storage device 15 can be transported to the configuration device for configuration of metal nitrate solution. The nitric acid solution used for absorption in the regeneration device comes from the nitric acid solution of a certain concentration returned from the washing device 7, the cooling device 8 and the oxidation synthesis device 10.

[0074] The residual nitrogen oxides in the high-temperature flue gas that have not been converted into nitric acid enter the washing device 7 for washing and the cooling device for cooling, and then enter the oxidation synthesis device 10, where the nitrogen oxides are oxidized into nitric acid and enriched, and are returned to the regeneration device 6 step by step through pressurization for absorption spraying.

[0075] Preferably, the washing device 7 is connected to a washing circulation pipeline.

[0076] Preferably, the cooling device 8 is connected to a circulation device 1 for circulating and cooling the flue gas.

[0077] Preferably, the oxidation synthesis device 10 is connected to a circulation device 2 for nitric acid circulation.

[0078] Preferably, in order to achieve emission standards for residual nitrogen oxides in exhaust gas, the residual nitrogen oxide exhaust gas in the oxidation synthesis device 10 enters the catalytic reaction device 13 after passing through the heat exchanger 12, and undergoes catalytic reduction reaction at a reaction temperature of 280 to 420°C, and is converted into N2 to achieve emission standards.

[0079] In this embodiment, metal oxides are prepared using metal nitrates such as nickel, cobalt, manganese, iron, copper, and zinc, and a spray pyrolysis method is adopted, and temperature zone pyrolysis is performed in a reactor. Compared with traditional coprecipitation and calcination processes, this method is more economical, has lower operating costs, and is more applicable. Since the nitrates are completely decomposed, the prepared metal oxides are of higher purity, and the residual nitrate ions in the product are lower. Under good control, the subsequent treatment of the metal oxides does not require water washing, which can greatly reduce the consumption of pure water and the operating costs. The high-temperature flue gas generated can be absorbed and treated by a recovery and purification unit to obtain a nitric acid solution, which can be reused. At the same time, the system also recovers the water medium in the configured solution to reduce the water consumption of the system. Under reasonable operation, no wastewater, waste residue, or substandard waste gas is discharged, which is energy-saving and environmentally friendly and suitable for large-scale industrial production.

[0080] Those skilled in the art will appreciate that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention. Although embodiments of the present invention have been described, it should be understood that the present invention should not be limited to this embodiment, and those skilled in the art can make changes and modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A method for preparing a battery metal oxide precursor by spray pyrolysis of nitrate, characterized in that: The following steps are involved: preparing a metal nitrate mixed solution; The metal nitrate mixed solution is atomized and sprayed into a reaction furnace, and pyrolyzed in different heating temperature zones in the reaction furnace to obtain a metal oxide mixture and high-temperature flue gas; The high-temperature flue gas is treated by waste heat recovery and then enters a regeneration device for recovery to obtain regenerated nitric acid; The metal oxide mixture is secondary heated at the bottom of the reaction furnace.

2. The method for preparing battery metal oxide precursors by nitrate spray pyrolysis according to claim 1, characterized in that: The metal nitrate mixed solution includes a nickel nitrate solution, a cobalt nitrate solution and a manganese nitrate solution, and also includes at least one of a ferric nitrate solution, a copper nitrate solution and a zinc nitrate solution.

3. The method for preparing battery metal oxide precursors by nitrate spray pyrolysis according to claim 1, characterized in that: The heating temperature of the top of the reaction furnace is 280-380°C, the heating temperature of the middle of the reaction furnace is 550-1000°C, and the heating temperature of the bottom of the reaction furnace is 360-550°C.

4. The method for preparing a battery metal oxide precursor by spray pyrolysis of nitrate according to claim 1, characterized in that: The total concentration of metal ions contained in the metal nitrate mixed solution is 100-180 g / L.

5. The method for preparing battery metal oxide precursors by nitrate spray pyrolysis according to claim 4, characterized in that: The metal nitrate mixed solution is concentrated before entering the reaction furnace, and the total concentration of metal ions contained in the concentrated solution is 125-270 g / L.

6. The method for preparing battery metal oxide precursors by nitrate spray pyrolysis according to claim 1, characterized in that: The atomized spray droplet diameter D of the metal nitrate mixed solution 32 20~300μm.

7. The method for preparing battery metal oxide precursors by nitrate spray pyrolysis according to claim 1, characterized in that: The particle size D of the oxide particles in the metal oxide mixture 50 0.5~75μm.

8. The method for preparing battery metal oxide precursors by nitrate spray pyrolysis according to claim 1, characterized in that: The waste heat recovery treatment of the high-temperature flue gas includes heat exchanging the high-temperature flue gas with a metal nitrate mixed solution to concentrate the metal nitrate mixed solution.

9. The method for preparing battery metal oxide precursors by nitrate spray pyrolysis according to claim 1, characterized in that: The metal nitrate mixed solution atomization spraying adopts one of high-pressure liquefaction spraying, airflow double-fluid spraying and multi-fluid spraying.

10. A system for preparing battery metal oxide precursors by spray pyrolysis of nitrates, characterized in that: It includes a spray pyrolysis unit for metal nitrate mixed solution reaction and a recovery and purification unit for high-temperature flue gas recovery. The spray pyrolysis unit includes a reaction furnace, which is provided with multiple heating mechanisms. The recovery and purification unit includes a regeneration device, which is connected to the flue gas outlet of the reaction furnace.

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