A process for producing metal oxides by spray roasting nitrates

Abstract

To provide a process for producing a metal oxide by a spray-roasting method, in which the size of the produced particles can be controlled, the purity of the product is high, the dispersibility of the particles is good, the production efficiency is high, and the process temperature is low.SOLUTION: A nitrate solution is filtered to remove impurities, and then concentrated in a preliminary concentrator before being supplied to a roasting furnace. Using a roasting furnace supply pump, the nitrate solution is sprayed into the roasting furnace under pressure to undergo spray roasting decomposition. After roasting the nitrate in the roasting furnace, the temperature of the resulting roasting furnace gas is reduced using the nitrate solution. The furnace gas is then cooled, absorbed, re-cooled, and re-absorbed to produce regenerated nitric acid. This feature represents an improvement over conventional methods.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of roasting processes, and in particular to a process for producing metal oxides by spray roasting nitrates. [Background technology]

[0002] The spray roasting method is a very promising material preparation method. Compared with traditional preparation techniques, it has many advantages, such as controllable particle size, high product purity, good particle dispersibility, high production efficiency, and low process temperature, and has been applied in many fields of materials science.

[0003] With existing technologies, such as the system for producing tricobalt tetroxide using a spray roasting method disclosed in Chinese Patent No. 201921313792.2 and the system and production process for producing tricobalt tetroxide using a spray roasting method disclosed in Chinese Patent No. 201910747775.8, when chlorides are used to produce metal oxides in a spray roasting furnace, the chlorides have high thermal decomposition temperatures and are difficult to decompose, which means that the chloride ions in the metal oxide tend to exceed the standard. As this technology is not suitable for producing metal oxides, a roasting process suitable for metal oxides is required. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Patent No. 201921313792.2 [Patent Document 2] Chinese Patent No. 201910747775.8 Summary of the Invention

[0005] An object of the present invention is to provide a process for producing metal oxides by spray roasting nitrates.

[0006] To achieve the above objectives, the present invention is implemented by the following technical solutions:

[0007] The present invention includes the following steps S1 to S6.

[0008] In S1, the nitrate solution is filtered to remove impurities, then concentrated in a pre-concentrator and fed to a roasting furnace. The nitrate solution is then sprayed into the roasting furnace under pressure by a roasting furnace feed pump to carry out spray roasting decomposition. The nitrate decomposition products include metal oxides, NO2 gas, and water vapor.

[0009] In S2, the furnace gas from the roaster is transported to the pre-concentrator, where the roaster gas generated after spraying and roasting nitrate in the roaster is cooled by the pre-concentrator, and at the same time, the newly introduced nitrate solution is concentrated and the dust in the roaster gas is removed.

[0010] In S3, the metal oxides are dropped from the bottom of the roasting furnace, and the conveying air generated by the conveying fan and filtered by the filter transports the metal oxide powder to the powder silo, where the metal oxides are cooled as they pass through the conveying air.A sintered plate dust collector is installed above the powder silo, and a packaging machine for packaging the metal oxides is installed below the powder silo.

[0011] In S4, the roaster gas that has passed through the pre-concentrator is fed into a primary cooling tower, a primary absorption tower, a secondary cooling tower, a secondary absorption tower, or a multi-stage cooling tower and absorption tower that are staggered from one another, where the NO2 gas is absorbed to produce regenerated nitric acid. Once the absorption is complete, the temperature of the roaster gas is lowered and then fed into the exhaust gas fan.

[0012] In S5, a liquid alkali scrubber installed behind the exhaust gas fan scrubs the roaster gas again.

[0013] In S6, the gas that has passed through the scrubbing tower is cleaned with a wet electrostatic precipitator, and then put into a chimney and discharged to the outside.

[0014] Preferably, the preconcentrator is a Venturi preconcentrator. The preconcentrator reduces the temperature of the roaster gas from 300-500°C to 95°C or less and concentrates the nitrate solution to 15-35%. In step S1, the reaction temperature in the roaster is 400-850°C. In step S4, the temperature of the roaster gas is reduced to 40°C or less upon completion of absorption.

[0015] The roaster further comprises a roaster body, a rotary valve, a furnace body exhaust pipe, a combustion assembly conduit, a gas regulating valve, an air regulating valve, an exhaust temperature detector, an exhaust temperature detector, an exhaust pressure detector, a furnace body temperature detector, a conduit front temperature detector, a conduit rear temperature detector, a spray nozzle, a solution regulating valve, a water supply regulating valve, and a compressed air regulating valve, wherein the lower end outlet of the roaster body is connected to the rotary valve, the upper end of the roaster body is provided with an exhaust port, the exhaust port of the roaster body is connected to one end of the furnace body exhaust pipe, the discharge end of the spray nozzle is located at an upper stage within the roaster body, the combustion end of the combustion assembly conduit is located inside the roaster body, the gas regulating valve and the air regulating valve are located at the supply end of the combustion assembly conduit, and the gas regulating valve and the air regulating valve are connected to the supply end of the roaster body. Located outside the roasting furnace body, the discharge temperature detector is provided at the supply end of the rotary valve, the exhaust temperature detector and the exhaust pressure detector are respectively provided on the outer walls of the supply end and the discharge end of the roasting furnace body exhaust pipe, there are a plurality of furnace body temperature detectors, each provided on a side wall of the roasting furnace body, the front-end temperature detector and the rear-end temperature detector are respectively provided on the side walls of the discharge end and the supply end of the combustion assembly roasting furnace, the supply end of the spray nozzle is simultaneously connected to the discharge ends of the feedwater regulating valve, the compressed air regulating valve and the solution regulating valve, the supply end of the solution regulating valve is connected to a solution supply assembly, the supply end of the feedwater regulating valve is connected to a feedwater assembly, and the supply end of the compressed air regulating valve is connected to an air supply device.

[0016] As an improvement, a block crusher and a crusher drive motor are provided between the discharge end of the roasting furnace body and the rotary valve, the supply end of the block crusher is connected to the discharge end of the roasting furnace body, the discharge end of the block crusher is connected to the rotary valve, and the drive end of the block crusher is connected to the drive output shaft of the crusher drive motor.

[0017] Preferably, the number of the spray nozzles is plural, and all of the spray nozzles are located at an upper stage in the roasting furnace body.

[0018] As an improvement, an air flow sensor is provided between the combustion assembly conduit and the air regulating valve, a gas flow sensor is provided between the combustion assembly conduit and the gas regulating valve, and a flame detector is provided in the combustion assembly conduit, with a sensing end of the flame detector located within the combustion assembly conduit.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention is a process for producing metal oxides by spray roasting nitrates. Compared with the prior art, the present invention improves the process and equipment based on the prior art, and by using nitrate spray pyrolysis to produce ternary battery materials, the purity of the metal oxides is improved and the chloride ion standard is avoided. The improved roasting furnace has the advantages of controllable particle size, high product purity, good particle dispersibility, high production efficiency, and low process temperature, and is worthy of popularization and application. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a flow diagram illustrating the process of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing the structure of a roasting furnace of the present invention. [Figure 3] 1 is a schematic diagram showing the structure of a combustion assembly of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will be further described below in conjunction with figures and specific examples, but the illustrative examples and descriptions of the invention are intended to interpret the invention and not to limit it.

[0023] As shown in FIG. 1, the present invention includes the following steps S1 to S6.

[0024] In S1, the nitrate solution is filtered to remove impurities, then concentrated in a pre-concentrator and fed to a roasting furnace. The roasting furnace feed pump then sprays the nitrate solution into the roasting furnace under pressure to carry out spray roasting decomposition. The nitrate decomposition products include metal oxides, NO2 gas, and water vapor (which also contains oxygen, NO, NO2, N2O3, and N2O4, with NO2 being the main component).

[0025] In S2, the furnace gas from the roaster is transported to the pre-concentrator, where the roaster gas (NO2, H2O, combustion exhaust gas, dust) generated after spray roasting of nitrates in the roaster is cooled in the pre-concentrator to lower the temperature of the roaster gas from 300-500°C to below 95°C, while concentrating the newly introduced nitrate solution (concentrating the nitrate solution to 15-35%) and removing the dust in the roaster gas.

[0026] In S3, the metal oxides are dropped from the bottom of the roasting furnace, and the conveying air generated by the conveying fan and filtered by the filter transports the metal oxide powder to the powder silo. The metal oxides are cooled as they pass through the conveying air, and are then cleaned and purified by a sintered plate dust collector installed at the top of the powder silo. The purified air is then discharged, and the powder collected at the bottom by the sintered plate dust collector is dropped back into the powder silo, and a packaging machine is installed at the bottom of the powder silo to package the metal oxides.

[0027] In S4, the roaster gas that has passed through the pre-concentrator is fed into a primary cooling tower, a primary absorption tower, a secondary cooling tower, a secondary absorption tower, or a multi-stage cooling tower and absorption tower that are staggered from one another, where the NO2 gas is absorbed to produce regenerated nitric acid. Once the absorption is complete, the temperature of the roaster gas is lowered and then fed into the exhaust gas fan.

[0028] In S5, a liquid alkali (or ammonia water) washing tower installed behind the exhaust gas fan washes the roaster gas again, and the washed wastewater is discharged to a sewage treatment plant where it is treated to meet emission standards.

[0029] In S6, the gas that passes through the scrubber is cleaned using a wet electrostatic precipitator before being pumped into a chimney and discharged to the outside. The scrubber wastewater is also discharged to a sewage treatment plant for treatment. The flue gas temperature is below 40°C, the water vapor content is less than 10%, and other indicators are lower than China's emission standards. As an alternative technical solution, the gas that passes through the scrubber can also be denitrified using selective catalytic reduction (SCR) technology to reduce nitrogen oxides to the standard level, before being pumped into a chimney and discharged to the outside.

[0030] Nitrogen oxide absorption is carried out using the cooling + absorption + cooling + absorption method, which produces HNO3 and helps increase its concentration. The production of nitric acid through the absorption of nitrogen oxides is an exothermic reaction, and low temperatures are advantageous for nitrogen oxide absorption, so the roaster gas must be cooled to below 35°C. Dilute nitric acid is useful for absorbing nitrogen oxides, and the dilute nitric acid produced by secondary absorption is used as the absorbent in the primary absorption tower. Nitric acid is produced at the bottom of the primary absorption tower and discharged to the nitric acid tank.

[0031] Preferably, the preconcentrator is a Venturi preconcentrator. The preconcentrator reduces the temperature of the roaster gas from 300-500°C to 95°C or less and concentrates the nitrate solution to 15-35%. In step S1, the reaction temperature in the roaster is 400-850°C (a temperature below 400°C significantly reduces the reaction efficiency, while a temperature above 850°C affects the particle morphology of the generated metal oxide). In step S4, the temperature of the roaster gas is reduced to 40°C or less upon completion of absorption.

[0032] 2 and 3, the roaster includes a roaster body 1, a rotary valve 8, a furnace body exhaust pipe 11, a combustion assembly conduit 2, a gas regulating valve 15, an air regulating valve 16, an exhaust temperature detector 10, an exhaust temperature detector 12, an exhaust pressure detector 13, a furnace body temperature detector 14, a conduit front temperature detector 17, a conduit rear temperature detector 18, a spray nozzle 3, a solution regulating valve 4, a water supply regulating valve 5, and a compressed air regulating valve 6. The lower end outlet of the roaster body 1 is connected to the rotary valve 8. The upper end of the roaster body 1 is provided with an exhaust port. The exhaust port of the roaster body 1 is connected to one end of the furnace body exhaust pipe 11. The discharge end of the spray nozzle 3 is located at an upper part of the roaster body 1. The combustion end of the combustion assembly conduit 2 is located inside the roaster body 1. The gas regulating valve 15 and the air regulating valve 16 are located at the supply end of the combustion assembly conduit 2. the air regulating valve 16 is located outside the roasting furnace body 1; the discharge temperature detector 10 is installed at the supply end of the rotary valve 8; the exhaust temperature detector 12 and the exhaust pressure detector 13 are installed on the outer walls of the supply end and discharge end of the furnace body exhaust pipe 11, respectively; there are multiple furnace body temperature detectors 14, and the multiple furnace body temperature detectors 14 are installed on the side walls of the roasting furnace body 1, respectively; the front-end temperature detector 17 and the rear-end temperature detector 18 are installed on the side walls of the discharge end and supply end of the combustion assembly duct 2, respectively; the supply end of the spray nozzle 3 is simultaneously connected to the discharge ends of the feedwater regulating valve 5, the compressed air regulating valve 6, and the solution regulating valve 4; the supply end of the solution regulating valve 4 is connected to a solution supply assembly; the supply end of the feedwater regulating valve 5 is connected to a feedwater assembly; and the supply end of the compressed air regulating valve 6 is connected to an air supply device.

[0033] As an improvement, a block crusher 7 and a crusher drive motor 9 are provided between the discharge end of the roasting furnace main body 1 and the rotary valve 8, the supply end of the block crusher 7 is connected to the discharge end of the roasting furnace main body 1, the discharge end of the block crusher 7 is connected to the rotary valve 8, and the drive end of the block crusher 7 is connected to the drive output shaft of the crusher drive motor 9.

[0034] Preferably, the number of spray nozzles 3 is plural, and all of the spray nozzles 3 are located at an upper stage in the roasting furnace body 1.

[0035] As an improvement, an air flow sensor 19 is provided between the combustion assembly conduit 2 and the air regulating valve 16, a gas flow sensor 20 is provided between the combustion assembly conduit 2 and the gas regulating valve 15, and a flame detector 21 is provided in the combustion assembly conduit 2, with the detection end of the flame detector 21 located inside the combustion assembly conduit 2.

[0036] A pre-conduit temperature detector 17 is installed at the exit of the combustion assembly conduit 2 to detect the temperature of the high-temperature gas entering the roaster after combustion has finished. This temperature is controlled to 800-1200°C to ensure the pyrolysis reaction within the roaster is completed. Using only one thermometer for detection only detects the combustion reaction temperature of the high-temperature gas, not the gas temperature after combustion has finished, which is detrimental to accurate control of the reaction temperature within the roaster. Installing the pre-conduit temperature detector 17 to detect the temperature of the high-temperature gas entering the roaster after combustion has finished helps control the reaction temperature within the roaster, improve reaction efficiency, and control metal oxide particles.

[0037] The atomization method for the solution entering the roasting furnace is multi-material atomization, which reduces the size of the atomized particles and makes the spray roasting reaction easier. A furnace body temperature detector 14 is installed in the linear section of the roasting furnace to detect the temperature at each stage inside the roasting furnace, which is useful for controlling the reaction temperature inside the roasting furnace.

[0038] The roasting process in the roasting furnace is as follows:

[0039] In step 1, the solution is fed into the spray nozzle 3 through the solution adjusting valve 4, and compressed air is also fed into the spray nozzle 3 through the compressed air adjusting valve 6, atomizing the solution into particles of 10-300 μm, which are then sprayed into the inside of the roasting furnace body 1 to perform spray roasting.

[0040] In step 2, a thermal decomposition reaction is carried out inside the roasting furnace body 1 to produce metal oxides and nitrogen oxides.

[0041] In step 3, the nitrogen oxide gases and combustion exhaust gases produced by the reaction, as well as excess air, are discharged from the top of the roasting furnace body 1, and the temperature and pressure are detected by an exhaust temperature detector 12 and an exhaust pressure detector 13. The gas in the roasting furnace body 1 is then sent to the subsequent cooling and absorption step.

[0042] In step 4, the metal oxide produced by the reaction is fed from the bottom of the roasting furnace body 1 through a block crusher 7 and a rotary valve 8 into a powder conveying system.

[0043] In step 5, the gas and air that enter the combustion assembly through the gas regulating valve 15 and the air regulating valve 16 are combusted in the combustion assembly conduit 2, and the high-temperature gas after combustion is introduced into the roasting furnace body 1 so as to supply heat to the reaction inside the roasting furnace body 1. [Example]

[0044] In S1, the nitrate solution is filtered to remove impurities, then concentrated in a pre-concentrator and fed to a roasting furnace. The roasting furnace feed pump sprays the nitrate solution into the roasting furnace under pressure, where it is subjected to spray roasting decomposition.

[0045] In S2, the furnace gas from the roaster is transported to the pre-concentrator, and the roaster gas generated after spraying and roasting nitrate in the roaster is cooled by the pre-concentrator to lower the temperature of the roaster gas from 300°C to below 85°C, while concentrating the nitrate solution to 15% and removing dust from the roaster gas.

[0046] In S3, the metal oxides are dropped from the bottom of the roasting furnace, and the conveying air generated by the conveying fan and filtered by the filter transports the metal oxide powder to the powder silo. The metal oxides are cooled as they pass through the conveying air, and are then cleaned and purified by a sintered plate dust collector installed at the top of the powder silo. The purified air is then discharged, and the powder collected at the bottom by the sintered plate dust collector is dropped back into the powder silo, and a packaging machine is installed at the bottom of the powder silo to package the metal oxides.

[0047] In S4, the roaster gas that has passed through the pre-concentrator is fed into a primary cooling tower, a primary absorption tower, a secondary cooling tower, a secondary absorption tower, or a multi-stage cooling tower and absorption tower that are staggered from one another, where the NO2 gas is absorbed to produce regenerated nitric acid. Once the absorption is complete, the temperature of the roaster gas is lowered and then fed into the exhaust gas fan.

[0048] In S5, a liquid alkali (or ammonia water) washing tower installed behind the exhaust gas fan washes the roaster gas again, and the washed wastewater is discharged to a sewage treatment plant for treatment to meet emission standards.

[0049] At S6, the gas that passes through the scrubbing tower is cleaned with a wet electrostatic precipitator before being discharged into a chimney and the washing wastewater from the wet electrostatic precipitator is also discharged to a sewage treatment plant for treatment. The temperature of the flue gas is below 40°C, the water vapor content is less than 10%, and other indicators are lower than China's emission standards.

[0050] The metal oxides roasted in Example 1 above were tested and their technical parameters are shown in Table 1 below.

[0051] Particle size characteristic parameter table 1 (unit: μm) JPEG0007775362000001.jpg18170

[0052] Here, D represents the diameter, and 03, 06...97, 98 represent percentages. For example, D03 = 0.88 μm means that when the cumulative distribution ratio from small particle diameters to large particle diameters reaches 3% in the particle size distribution, the corresponding particle diameter value is 0.88 μm. In this embodiment, the median diameter (D50) is 20 μm, the volume-based average diameter D[4,3] is 24.39 μm, and the area-based average diameter D[3,2] is 5.76 μm. [Example]

[0053] The difference from Example 1 is that the preconcentrator reduces the roaster gas temperature from 500°C to 90°C and concentrates the nitrate solution to 35%.

[0054] The roasted metal oxides in Example 2 above were tested and their technical parameters are shown in Table 2 below.

[0055] Particle size characteristic parameter table 2 (unit: μm) JPEG0007775362000002.jpg18170

[0056] Here, D represents the diameter, and 03, 06...97, 98 represent percentages. For example, D03 = 0.6 μm means that when the cumulative distribution ratio from small particle diameters to large particle diameters reaches 3% in the particle size distribution, the corresponding particle diameter value is 0.6 μm. In this embodiment, the median diameter (D50) is 10.0 μm, the volume-based average diameter D[4,3] is 12.09 μm, and the area-based average diameter D[3,2] is 2.85 μm. [Example]

[0057] The difference from Example 1 is that the preconcentrator reduces the temperature of the roaster gas from 380°C to 80°C and concentrates the nitrate solution to 25%.

[0058] The roasted metal oxides in Example 3 above were tested and their technical parameters are shown in Table 3 below.

[0059] Particle size characteristic parameter table 3 (unit: μm) JPEG0007775362000003.jpg17170

[0060] Here, D represents the diameter, and 03, 06...97, 98 represent percentages. For example, D03 = 0.79 μm means that when the cumulative distribution ratio from small particle diameters to large particle diameters reaches 3% in the particle size distribution, the corresponding particle diameter value is 0.79 μm. In this embodiment, the median diameter (D50) is 4.9 μm, the volume-based average diameter D[4,3] is 3.98 μm, and the area-based average diameter D[3,2] is 0.83 μm.

[0061] As can be seen from the results of Examples 1 to 3 above, the technical effect obtained by the process parameters of Example 3 is superior to that of Examples 1 and 2.

[0062] The technical solution of the present invention is not limited to the above specific embodiments, and all technical modifications made according to the technical solution of the present invention shall fall within the protection scope of the present invention. [Explanation of symbols]

[0063] In the diagram, there is a roasting furnace body 1, a combustion assembly conduit 2, a spray nozzle 3, a solution adjusting valve 4, a water supply adjusting valve 5, a compressed air adjusting valve 6, a block pulverizer 7, a rotary valve 8, a pulverizer drive motor 9, an exhaust temperature detector 10, a furnace body exhaust pipe 11, an exhaust temperature detector 12, an exhaust pressure detector 13, a furnace body temperature detector 14, a gas adjusting valve 15, an air adjusting valve 16, a temperature detector before the conduit 17, a temperature detector after the conduit 18, an air flow sensor 19, a gas flow sensor 20, and a flame detector 21.

Claims

1. A step S1 in which a metal nitrate solution is filtered to remove impurities, then concentrated in a preconcentrator, and fed to a roasting furnace, and the metal nitrate solution is sprayed into the roasting furnace under pressure by a roasting furnace feed pump to perform spray roasting decomposition, wherein the nitrate is decomposed into metal oxides, NOx, and the like as decomposition products. ２ Step S1, in which the reaction temperature in the roasting furnace is set to 400 to 850°C and higher than the thermal decomposition temperature of the metal nitrate, depending on the metal nitrate; a step S2 of conveying furnace gas from the roaster to a preconcentrator, cooling the furnace gas obtained by roasting in the roaster through the preconcentrator, and simultaneously concentrating a metal nitrate solution introduced into the preconcentrator, and removing dust from the furnace gas using the metal nitrate solution, wherein the preconcentrator is a Venturi preconcentrator, and cooling the furnace gas from 300-500°C to 95°C or less, and concentrating the metal nitrate solution to 15-35%; Step S3: the powdered metal oxide cooled by the preconcentrator falls to the bottom of the roasting furnace, and a conveying fan supplies conveying air to the roasting furnace, the conveying air is filtered by a filter, and the metal oxide powder is conveyed to a powder silo while cooling the metal oxide powder; and Step S3: a sintered plate dust collector is provided above the powder silo, and a packaging machine is provided below the powder silo for packaging the metal oxide. The furnace gas cooled and discharged by the pre-concentrator is introduced into a primary cooling tower, a primary absorption tower, a secondary cooling tower, a secondary absorption tower, or a multi-stage cooling tower and an absorption tower that are staggered with each other, and NO ２ Step S4: absorb the gas to generate regenerated nitric acid, and when the absorption is completed, lower the temperature of the furnace gas and then let it into the exhaust gas fan; Step S5: a liquid alkali scrubber installed behind the exhaust gas fan scrubs the furnace gas again; Step S6: removing dust from the gas that has passed through the scrubbing tower using a wet electrostatic precipitator, and then discharging the gas to the outside through a chimney; The roasting furnace includes a roasting furnace body (1), a rotary valve (8), a furnace body exhaust pipe (11), a combustion assembly conduit (2), a gas regulating valve (15), an air regulating valve (16), an exhaust temperature detector (10), an exhaust temperature detector (12), an exhaust pressure detector (13), a furnace body temperature detector (14), a conduit front temperature detector (17), a conduit rear temperature detector (18), a spray nozzle (3), a solution regulating valve (4), a water supply regulating valve (5), and a compressed air regulating valve (6), and the lower end outlet of the roasting furnace body (1) is connected to the rotary valve (8). (8), an exhaust port is provided at the upper end of the roasting furnace body (1), the exhaust port of the roasting furnace body (1) is connected to one end of the furnace body exhaust pipe (11), the discharge end of the spray nozzle (3) is located at the upper stage in the roasting furnace body (1), the combustion end of the combustion assembly flue (2) is located inside the roasting furnace body (1), the gas regulating valve (15) and the air regulating valve (16) are provided at the supply end of the combustion assembly flue (2), and the gas regulating valve (15) and the The air regulating valve (16) is located outside the roasting furnace body (1), the discharge temperature detector (10) is provided at the supply end of the rotary valve (8), the exhaust temperature detector (12) and the exhaust pressure detector (13) are provided on the outer wall of the supply end and the discharge end of the furnace body exhaust pipe (11), respectively, there are a plurality of furnace body temperature detectors (14), and the plurality of furnace body temperature detectors (14) are provided on the side wall of the roasting furnace body (1), the pre-vention temperature detector (17) and the post-vention temperature detector (18) are provided on the outer wall of the roasting furnace body (1), Stage temperature detectors (18) are respectively provided on the side walls of the discharge end and the supply end of the combustion assembly conduit (2); the supply end of the spray nozzle (3) is simultaneously connected to the discharge ends of the feedwater regulating valve (5), the compressed air regulating valve (6) and the solution regulating valve (4); the supply end of the solution regulating valve (4) is connected to the solution supply assembly, the supply end of the feedwater regulating valve (5) is connected to the water supply assembly, and the supply end of the compressed air regulating valve (6) is connected to an air supply device. A method for producing metal oxides by spray roasting nitrates.

2. 2. The method for producing metal oxides by spray roasting nitrates according to claim 1, wherein in step S4, the temperature of the furnace gas is lowered to 40° C. or less upon completion of absorption.

3. 2. The method for producing metal oxides by spray roasting nitrates according to claim 1, wherein a block crusher (7) and a crusher drive motor (9) are provided between the discharge end of the roasting furnace body (1) and the rotary valve (8), the supply end of the block crusher (7) is connected to the discharge end of the roasting furnace body (1), the discharge end of the block crusher (7) is connected to the rotary valve (8), and the drive end of the block crusher (7) is connected to the drive output shaft of the crusher drive motor (9).

4. 2. The method for producing metal oxides by spray roasting nitrates according to claim 1, wherein the number of spray nozzles (3) is multiple, and all of the multiple spray nozzles (3) are located at an upper stage in the roasting furnace body (1).

5. 2. The method for producing metal oxides by spray roasting nitrates according to claim 1, wherein an air flow sensor is provided between the combustion assembly conduit and the air regulating valve, a gas flow sensor is provided between the combustion assembly conduit and the gas regulating valve, and a flame detector is provided in the combustion assembly conduit, the detecting end of the flame detector being located inside the combustion assembly conduit.

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