CN1220926A - Technology and equipment for preparation of tungsten carbide-nickel-iron series nanometer grade composit powder - Google Patents

Abstract

A process for preparing nm-class hard compound alloy powder in tungsten carbide-nickel-iron series features use of gas-flow rotary furnace for reduction and carbonization. Said gas-flow rotary furnace has an enclosed sysetm composed of blade-type centrifugal pump, internal furnace tuber with open ends and external tubes with enclosed top end. The compound oxide powder and carbon-containing gas take part in reduction and carbonization at 800-1100 deg.C for 1-4 hr in the rotary furnace which uses inert gas or hydrogen as drive gas to obtain nm-class hard WC-Ni-Fe alloy powder. Its advantages are high efficiency, simple process and stable performance.

Description

Process and equipment for preparing tungsten carbide-nickel-iron series nano composite powder

The invention belongs to a preparation process of nanometer ultrafine grain WC-Ni-Fe series hard alloy composite powder, and can be used for preparing WC-Co series, WC-Ni series, WC-Fe series nanometer hard alloy composite powder and W-Ni-Fe series, W-Ni-Cu series nanometer ultrafine grain high specific gravity alloy powder.

The application range of the hard alloy is very wide, and in recent years, due to the exhaustion of the world cobalt ore resources, novel tungsten-nickel series and tungsten-nickel-iron series hard alloys are gradually appeared and rapidly developed. However, these alloys still cannot meetthe requirements of the modern high-tech on the hard alloy, so that a great deal of manpower and material resources are invested in the countries of America, Japan and English, and the production technology of the ultrafine particle hard alloy is rapidly developed.

In the past, hard alloy powder with the particle size of less than 1 mu m is prepared by preparing fine tungsten powder, carbonizing the fine tungsten powder to prepare fine tungsten carbide (WC) powder, and performing long-time enhanced ball milling and crushing to obtain the hard alloy powder with the average particle size of 1 mu m. Production practices of countries around the world for over seventy years prove that the process cannot be used for preparing the ultrafine grain hard alloy powder with the WC average grain size of less than 0.5 mu m. But also the result of the intensified ball milling fracture can lead to powder dirtying, a sharp increase in activity and the risk of severe oxidation or explosion.

From the international online search of DA1LOG system, six general related documents, two patent documents, 2, 8, 32, 38, 200, 350, 351, 344 and 347 documents, it can be seen that, in 1991, l.e.mc. candollish et al (world patent No. W091107244) of the university of Rugers and the published specification of the chinese patent application in 1994 (CN1086752A) both disclose techniques for preparing ultrafine grained cemented carbide powders using a fluidized bed apparatus. In 1997, the carbide factory owned by China issued a method for preparing carbide alloy with average grain size less than 0.5 μm by vapor deposition (CVD), and all the methods are used for preparing WC-Co series carbide alloy. The above methods have respective disadvantages, such as the fluidized bed method which cannot produce WC-Ni-Fe system cemented carbide powder and the large amount of consumed process gas. The dust removal equipment is huge, the actual yield is low, the heat energy utilization rate is low,and toxic solvent (ethylenediamine) is adopted in the solution preparation process, so that the environment is polluted.

The gas phase deposition (CVD) method cannot prepare WC-Ni-Fe series hard alloy composite powder, and has low yield, high cost, corrosive gas contained in waste gas and difficult continuous mass production.

The invention aims to provide a preparation technology for directly preparing WC-Ni-Fe series nanometer ultrafine particle hard alloy composite powder by reduction and carbonization in an airflow rotary furnace. Meanwhile, the method can also be used for preparing WC-Ni series, WC-Fe series and WC-Co series nanometer ultrafine particle hard alloy composite powder and W-Ni-Fe series and W-Ni-Cu series ultrafine particle high-specific gravity alloy powder.

The invention comprises a process for preparing tungsten carbide-nickel-iron series nano-scale hard alloy composite powder and a special equipment airflow rotary furnace for preparing the composite powder.

The airflow rotary furnace is shown in figure (2), and mainly comprises a sealing system composed of a vane type centrifugal pump (19), an inner furnace tube (18) with two open ends, an outer furnace tube (16) with a closed upper end and other main parts.

Centrifugal pumps of the vane type are common equipment in industry, where a negative pressure zone is formed in the inner tube (18) and a positive pressure zone is formed in the space between the inner and outer tubes due to the characteristics of the centrifugal pump when the vanes rotate. When gas and powder are filled in the furnace tube, the static gas and powder in the furnace tube become a multiphase suspension fluidized moving gas flow with a special motion law due to the rotation of the blades. The device is characterized inthat multiphase suspension fluidization air flow moves in two modes between a closed outer pipe (16) and an inner furnace pipe (18) with an upper opening and a lower opening. Firstly, the spiral rotary motion is performed between the inner pipe and the outer pipe from bottom to top around the outer wall of the inner pipe. Secondly, when the rotary airflow rises to the opening at the upper part of the inner pipe (16), under the action of negative pressure, the airflow enters the inner pipe to be gradually accelerated and is directly sprayed out from the lower opening of the inner pipe, and then the airflow is accelerated and pressurized by the vane type centrifugal pump (19) and enters the outer pipe to perform repeated spiral rotary motion.

The reduced composite oxide powder particles are suspended in a spirally rotating gas stream consisting of hydrogen (H)₂) Inert gas (N)₂Ar) and a carbon-containing gas (methane, ethane or CO). The supply amount of each gas is controlled by respective flow meters such as a hydrogen flow meter (22), an inert gas flow meter (23), and a carbon-containing gas flow meter (24). The revolving airflow is heated by a heating furnace (17) arranged outside the outer furnace tube. The temperature of the rotary air flow can be increased to 800-1100 ℃. With hydrogen (H) as a reducing agent₂) And under the conditions of a carbonizing agent (methane or CO) and high temperature (800-1100 ℃), carrying out reduction reaction on the composite oxide powder particles according to the following formula:

meanwhile, by utilizing the great difference of chemical potential of various metals for generating carbide, only tungsten powder particles in the reaction product are carbonized according to one of the following reaction formulas (7) and (8) at high temperature, and the tungsten powder is converted into tungsten carbide powder, but iron-nickel powder particles are not carbonized. Or

All the reactions shown in the reaction formulas (4) to (8) are simultaneously completed in a gas flow rotary furnace, and the phase transformation process achieves the purpose of transforming from a composite oxide phase (WO)₃+ NiO + FeO) to be finally converted into (WC + Ni + Fe) mixed phase powder, namely obtaining the composite powder of tungsten carbide powder and iron and nickel metal powder with very uniform components.

When the reaction is finished, the vane-type centrifugal pump (19) stops rotating, and the spiral rotary airflow stops moving. All the reacted powder of the partition plate (20) is opened and falls into a cooling box (31) under the action of gravity, and the cooled powder enters a material storage barrel (33) to finish the final preparation process of reduction carbonization.

The process of the present invention is that the nanometer level superfine hard alloy composite powder is prepared directly through reduction and carbonization in gas flow converter and inorganic salt containing W, Ni and Fe elements, such as H₂WO₄、NiCl₂、FeCl₂) The aqueous solution of (A), nano-scale ultra-fine composite oxide powder prepared by ultrasonic spray drying (thermal conversion), placing in a gas flow rotary furnace, and using inert gas (N)₂Ar) and hydrogen gas are taken as rotary driving gases, hydrogen reduction is carried out at 800-1100 ℃, carbon-containing gas such as methane, ethane or carbon monoxide gas is added for carbonization, and nano-scale ultrafine particle WC-Ni-Fe series hard alloy composite powder can be obtained by reducing and carbonizing for 1-4 hours at 800-1100 ℃. The inorganic salt aqueous solution containing W, Ni and Fe ions is prepared by the following two steps and method.

a. Dissolving tungstic acid powder in concentrated ammonia water, dissolving nickel chloride in water, and mixing the two to prepare solution A, thereby obtaining aqueous solution containing tungsten and nickel ions, wherein the reaction formula is as follows:

………(1)

………(2)

b. dissolving ferrous chloride in water to prepare a B solution containing iron ions, wherein the reaction formula is as follows:

………(3)

a, B the two solutions are mixed quickly before being input into a spray drying nozzle, so that W, Ni and Fe ions in the mixed solution can reach a uniform mixing state at a molecular level, and then ultrasonic spray drying (dehydration heat conversion) is carried out. The device is shown in figure (1), and can make the water solution containing (W, Ni, Fe) ions in a very short time (10)^-3Second) into very fine (less than 15nm) droplets with very high speed (400-500 m/s), and evaporating the water in the droplets under the action of hot air at 50-80 deg.C to quickly convert the water solution containing (W, Ni, Fe) ions into (WO) ions₃NiO and FeO) oxide phase, uniform in composition, and ultrafine in nanometer order.

The present invention has the advantages that the reduced composite oxide particles are always suspended in the rotary airflow and are crushed once by the airflow passing through the furnace bottom and the vane type centrifugal pump once in each circulation. When fine tungsten (or nickel, iron) particles having a high density are formed on the surface of the oxide particles, and when WC particles are formed on the surface of the tungsten powder, a large phase change stress is present in the heterogeneous interface, but it is not sufficient to separate the heterogeneous phase. The heterogeneous particles in the airflow rotary furnace are easy to break under the impact of the airflow and the blades, and the reaction surface is rapidly increased, so that the reaction speed can be improved, and WC particles can be further refined.

Compared with the fluidized bed, the powder particles in the airflow rotary furnace have longer time to suspend in the high-temperature reaction airflow and have more sufficient time to contact with the reaction gas, so that the reaction speed can be obviously improved, and the reaction time can be shortened. Obviously, in the existing reduction and carbonization process, the reaction materials are kept in a vessel, the reaction mechanism mainly depends on solid phase diffusion, so the reaction speed is very slow, the reaction time is longer, and the particles are easy to grow rapidly through evaporation and condensation due to accumulation. Therefore, the process used in the existing industrial production cannot prepare the nanometer ultrafine particle hard alloy composite powder.

As the operation gas of the gas flow rotary kiln, except for a very small part of the operation gas to be discharged with the waste gas (water vapor), most of the operation gas is always circulated between the inner and outer pipes and is not discharged out of the kiln. As a result, compared with fluidized bed, it not only can greatly save gas consumption, but also can obviously reduce heat loss brought away by hot gas flow, and can greatly raise heat utilization rate. More importantly, the gas flow rotaryfurnace can overcome the maximum weakness of the fluidized bed. Because the powder particles in the fluidized bed are subjected to upward jumping by means of the constantly upward blowing gas flow of the lower perforated plate and then fall back by gravity to achieve a floating jumping movement in the gas flow. When the air flow velocity is too high, the powder with smaller particle diameter will leave the high temperature zone and be discharged out of the furnace with the air flow, and when the air flow velocity is too low, the powder particles (especially particles with larger diameter) will be deposited on the porous plate to form a pile. In order to keep the powder particles in the high-temperature reaction zone and continuously suspend and jump, a huge and efficient dust removal system must be arranged in the fluidized bed to quickly and effectively separate the extremely fine powder particles from the operation gas, and the flow rate and the flow velocity of the gas flow system must be controlled for a long time so that the powder can be stably maintained in the high-temperature reaction zone for a long time to keep the suspension and jump state. Nevertheless, since the powder with the particle size of nanometer ultrafine particles is difficult to settle by gravity, the ultrafine powder particles are still carried away by the operation air flow in the fluidized bed, and thus, a huge dust removing and cleaning device is still required to be arranged at the tail part of the fluidized bed. In contrast, in the airflow rotary furnace, the powder particles are always in the closed furnace tube and do suspended rotary motion along with the airflow, and the powder particles do not need to be separated from the operation airflow, so the powder yield of the airflow rotary furnace is obviously higher than that of a fluidized bed, particularly the powder yield of a fine powder section.

The airflow rotary furnace has completely different working principle from the fluidized bed, so that the airflow rotary furnace has simple and reliable structure and low production cost. Is easy to be popularized and applied.

The invention is further described below with reference to the accompanying drawings:

FIG. 1 is a schematic view of the process flow and equipment connection for preparing composite oxide powder according to the present invention; FIG. 2 is a connection diagram of the structure, working principle and equipment of the air flow rotary furnace of the invention.

A solution A is prepared in a solution tank (1) according to the reaction formulas (1) and (2). Solution B was prepared in solution tank (2) according to equation (3). A, B two solutions are sent into a rapid mixing valve (4) through a liquid pump (3), are immediately sent into a central guide pipe of an ultrasonic atomizing nozzle (5) after being rapidly mixed, and immediately disperse the A + B mixed liquid into superfine droplets after air which is sent out by an air compressor (6) and heated by an air heater (9) enters the ultrasonic atomizing nozzle (5), and is preliminarily evaporated and dried. Then in the process of dropping the small droplets, the small droplets are sent out by an air blower (10) and heated by an air heater (9), and hot air sprayed out by an annular spray pipe (8) is dried to obtain the product containing the elements (WO)₃、NiO、FeO)The composite oxide powder of (3). The particle size of the powder is less than or equal to 30 nm. By changing A, B solution concentration, solution flow rate, air injection pressure and air temperature, the particle size and yield of the composite oxide can be controlled.

The composite oxide powder after spray (drying) heat conversion falls into the bottom of an atomizing tower (7) along with air flow, under the action of suction of a negative pressure conveying pipe, the composite oxide powder enters a gas-powder separator (12) along with the air flow through a control valve (11) and a pipeline, and under the action of centrifugal force, the powder rotates and slows down along the inner surface of the separator and falls into a negative pressure conveying tank (34) at the bottom of the separator under the action of gravity. The separated air is dedusted by a bag deduster (13) and then discharged to the atmosphere by a draught fan (14). The composite oxide powder in the negative pressure conveying tank (34) is conveyed to a bin (25) at the top of the airflow rotary furnace through a pipeline (26) under the negative pressure effect. Then directly enters an inner pipe of the airflow rotary furnace through a feeding valve (35) at the bottom of the storage bin, then the feeding valve (35) and the partition plate (20) are closed, a hydrogen pipe valve (22) is opened, and N is added₂A pipe valve (23) and a methane valve (24). The flow of each gas is adjusted, and simultaneously, a valve (32) is opened to enable the mixed gas to enter the rotary vane chamber through the gas inlet pipe (21). Starting the centrifugal impeller pump (19), rotating the impeller and pressurizing the mixture, and finallyThe mixed gas and the powder particles can form a suspended multiphase flow revolving gas flow. At the same time, the heating furnace (17) is heated. When the desired reduction-carbonization temperature is reached for a certain period of time, the composite oxide powder is immediately reduction-carbonized into a (WC + Ni + Fe) composite powder. Then the partition plate (20) is opened to drop the composite powder into the cooling chamber (31) for cooling and discharging.

In the reduction carbonization process, because reaction products (water vapor) need to be removed, the exhaust valve (15) is properly opened, the water vapor is directly discharged into the atmosphere through the three-way valve (30), or the reaction gas and the operation gas are recovered after the water is sent to the water remover (29) through the three-way valve (30) for cooling and water removal, then the dust is removed through the dust remover (28), the pressure is increased through the Roots pump (27), the reaction gas and the operation gas are sent to the gas heating furnace (9) for heating, and then the reaction gas and the operation gas are sent back to the rotating blade chamber for pressurization to be used as the operation gas and the reduction carbonization gas.

When the reduction carbonization is completed, the partition plate (20) is opened, and the (WC + Ni + Fe) composite powder is first lowered into the cooling chamber (31). After cooling, the mixture enters a charging bucket (33), and then the clapboard (20) is closed. When the other furnace is started, the feeding valve (35) is opened under the condition of keeping the high temperature (800-1100 ℃) in the furnace, and the composite oxide powder which is reduced and carbonized next time is added again. Continuous production can be realized by repeating the steps.

Example (b):

if necessary, nanometer ultrafine particle hard alloy composite powder with the components of WC, Ni and Fe = 90: 7: 3 is prepared. The method is completed according to the following steps. Firstly, preparing a solution:

1) calculating the components of each solute:

setting the final required hard alloy components as WC, Ni, Fe = x, y, z, the mol ratio of each componentThe molar ratio is as follows: $\mathrm{WC}:\mathrm{Ni}:\mathrm{Fe}=\frac{x}{249.916}:\frac{y}{58.69}:\frac{z}{126.75}\·\·\·\·\·\·\·\·\·\left(9\right)$

setting H to be added into the A + B mixed solution₂WO₄、NiCl₂、FeCl₂The weight ratio of (A) to (B) is 1: m: n, the respective molar ratios are: $H_{2}W{O}_4:\mathrm{NiC}{l}_2:\mathrm{FeC}{l}_2=\frac{l}{249.916}:\frac{m}{58.69}:\frac{n}{126.75}\·\·\·\·\·\·\·\·\·\left(10\right)$ from equation (9) = (10), the following equation can be obtained: $m=1.731\frac{l\·y}{x}\·\·\·\·\·\·\·\·\·\left(11\right)$ $n=1.777\frac{l\·z}{x}\·\·\·\·\·\·\·\·\·\left(12\right)$

in the above two formulas, x, y and z are alloy components (known numbers), and it is obvious that when l (i.e. tungstic acid H)₂WO₄) After the addition amount is determined, m and n can be obtained.

2) Preparation of solution A:

8000 gof tungstic acid (H) are added₂WO₄) Adding the powder into a liquid tank, adding 13 liters of water, adding 18 liters of concentrated ammonia water, closing the tank opening, continuously stirring and heating to 80 ℃, and sampling and testing to determine the concentration of the tungstic acid to be (20.5% +/-0.1% wt) after the dissolution is finished (20 minutes). Then, NiCl is calculated according to the equations (11) and (12)₂Weight (m) and FeCl₂Weight (n) because x: y: z = 90: 7: 13, l =8000 g (tungstic acid weight).

Therefore, NiCl is available₂Amount of addition

FeCl₂Amount of addition

Mixing NiCl₂Powder (622.22 g) was added to solution tank 1 and stirring continued, the temperature was raised to 80 ℃ and held for 5 minutes at which time solution A was prepared. The total volume of the solution A is V_A=31 l.

3) B, preparation of a solution:

FeCl (266.66 g) calculated from equation (12)₂Pouring the powder into a liquid tank (2), adding water, stirring, and continuously adding water to make the volume reach V_BAnd when the solution B is prepared, the solution B is prepared.

V_BIs (FeCl)₂) I.e., the total volume of solution B, which is related to the flow rate delivered by the two pumps at the time of spray change. If the flow rates of the solutions A and B are respectively Q_A,Q_B(ml/sec). During the spray change-over process, it is necessary to control $\frac{Q_A}{Q_B}=K$ (constant).

And the spray conversion of all the liquid is completed within t time, and the following balance is provided: $\frac{V_A}{Q_A}=\frac{V_B}{Q_B}=t\·\·\·\·\·\·\·\·\·\left(13\right)$ or $\frac{V_A}{V_B}=\frac{Q_A}{Q_B}\·\·\·\·\·\·\·\·\·\left(14\right)$ Jinjian Q_A/Q_B=4.5, apparently from the volume V of the a solution_AThe total volume of solution B calculated as follows:

thus, FeCl₂I.e. the total volume of the B solution should be adjusted to 6.88 litres. Second, spray thermal conversion to prepare composite oxide powder

The liquid flow rates of A and B are respectively controlled by a liquid pump (3) (ensured to be $\frac{Q_A}{Q_B}=4.5$ ) The two solutions A and B are fed into a quick mixing valve (4) according to the flow ratio and are quickly mixedAfter mixing, the mixture is immediately sent into a central flow guide pipe of an ultrasonic atomizing nozzle (5) for ultrasonic atomizing heat conversion. The flow rate of the A solution is substantially (Q)_A=4.5 ml/sec), and the flow rate of the B solution was (Q)_B=1 ml/sec), and the total flow rate of the a + B mixed solution is 5.5 ml/sec.

Compressed air (flow 16M) delivered by air compressor (6)³Hour), preheated to 80 ℃ by an air heating furnace (9), the output pressure is controlled to 0.4MPa, the mixture is sent into an ultrasonic atomizing nozzle (5) to form high-speed ultrasonic airflow, the A + B mixed solution is atomized into superfine droplets and is primarily dried, and then the superfine droplets are dried by rising hot air airflow to form solid composite oxide powder (the particle size of the composite oxide powder is less than 30 nm). The air blowing amount of the blower (10) is 1000M³In terms of hours.

A large amount of dried composite oxide powder and air fall to the bottom of the atomizing tower (7) along with the air flow, and enter an air-powder separator (12) through a control valve (11) and a pipeline. The powder falls to the bottom of the separator (12). The waste gas is dedusted by a bag-type deduster (13) and then passes through a draught fan (14) (draught amount 2000M)³Hour) was discharged to the atmosphere. Composite oxide powder is conveyed into a bin (25) at the top of the airflow rotary furnace through a negative pressure conveying tank (34) and a pipeline (26), the composite oxide powder controls the feeding amount (1600-2000 g/furnace) through a feeding valve (35), directly enters the airflow rotary furnace (the inner diameter of an outer pipe is phi 200mm), hydrogen (the flow rate is 4 liters/minute), methane (the flow rate is 0.8 liters/minute) and nitrogen (the flow rate is 4 liters/minute) are fed according to the operation program, a vane centrifugal pump (19) is started (the rotating speed is 650 weeks/minute), and meanwhile, the heating furnace (17) is electrified and heated. The incubation was carried out for 1.5 hours when the temperature was raised to 890 ℃. Stopping the rotation of the vane centrifugal pump (19), opening the partition plate (20) to enable the powder to fall into the cooling box (31), and then cooling and discharging. The powder obtained was analyzed by chemical analysis, x-ray diffraction analysis and transmission electron microscopy, and had the composition WC: Ni: Fe = 90: 7: 3. The average particle size of the powder is less than 30 nm. The particle shape is approximately spherical.

The alloy powder is pressed and formed by a conventional steel pressing die, and sintered for 1 hour at 1320 ℃ in a vacuum furnace to prepare the (WC, Ni, Fe)/(90: 7: 3) nano-scale ultrafine particle hard alloy. The average WC grain size in the alloy is less than or equal to0.48 nm. Bending strength 3000N, hardness HRA=92.5～92.6(kg/mm²)。

Claims (3)

1. A process for preparing the superfine hard alloy nanoparticles by reduction and carbonization in gas-flow converter features that the inorganic salt containing W, Ni and Fe, such as H, is used₂SO₄、NiCl₂、FeCl₂The aqueous solution of (A), the nano-scale ultra-fine composite oxide powder prepared by ultrasonic spray drying, placing in a gas flow rotary furnace, and using inert gas such as N₂Ar and hydrogen are used as rotation driving gas, hydrogen reduction is carried out at 800-1100 ℃, and carbon-containing gas is added for carbonization for 1-4 hours to obtain nanometer ultrafine particle WC-Ni-Fe hard alloy composite powder; the inorganic salt aqueous solution containing W, Ni and Fe ions is prepared by the following method:

a. dissolving tungstic acid powder in concentrated ammonia water, dissolving nickel chloride in water, and mixing the two to prepare solution A, wherein the reaction formula is as follows:

……(1)

………………(2)

b. dissolving ferrous chloride in water to prepare a B solution containing iron ions, wherein the reaction formula is as follows:

……………(3)

a, B the two solutions are mixed rapidly before being input into spray drying nozzle to make W, Ni and Fe ions in the mixed solution reach uniform mixing state at molecular level, and then ultrasonic spray drying is carried out to makethe water solution containing W, Ni and Fe ions in extremely short time (10)^-3Second) is dispersed into small droplets with the diameter less than 15nm and the speed of 400-500 m/s, and the water in the small droplets is evaporated under the action of hot air at 50-80 ℃ to quickly convert the water solution containing W, Ni and Fe ions into the water solution containing WO₃NiO, FeO oxide phase, homogeneous composition, nano-grade superfine compositeSolid powder of a double oxide.

2. The process for directly preparing the nano-scale ultrafine particle hard alloy composite powder by reduction and carbonization in a gas flow converter according to claim 1, wherein the added carbon-containing gas is methane, ethane or carbon monoxide gas, and the carbon-containing gas is simultaneously reduced and carbonized at the temperature of 800-1100 ℃ for 1-4 hours.

3. An equipment for preparing nanometer ultrafine particle hard alloy composite powder-airflow rotary furnace is characterized in that: the airflow rotary furnace mainly comprises a blade type centrifugal pump (19), an inner furnace tube (18) with openings at two ends and an outer furnace tube (16) with a closed upper end, wherein a sealing system is formed by main components, when the blades rotate, a negative pressure area is formed in the inner tube (18), and a positive pressure area is formed in a space between the inner tube and the outer tube, when gas and powder are filled in the furnace tube, the static gas and powder in the furnace tube can be changed into multiphase suspension fluidization movement airflow with a special movement rule due to the rotation of the blades, and multiphase suspension fluidization is generated, and the airflow moves between the closed outer tube (16) and the inner furnace tube (18) with the openings at the upper part and the lower part in two forms: the rotary air flow is in spiral rotary motion between the inner pipe and the outer pipe from bottom to top around the outer wall of the inner pipe, and the air flow enters the inner pipe to be gradually accelerated and directly sprayed out from a lower opening of the inner pipe under the action of negative pressure when the rotary air flow rises to an opening at the upper part of the inner pipe (16), is accelerated and pressurized by the vane centrifugal pump and then enters the outer pipe to perform repeated spiral rotary motion; the supply amount of the gas is controlled by respective flowmeters such as a hydrogen flowmeter (22), an inert gas flowmeter (23) and a carbon-containing gas flowmeter (24) to respectively control the rotary airflow, and the rotary airflow is heated by a heating furnace (17) arranged outside the outer furnace tube, so that the temperature of the rotary airflow can be increased to 800-1100 ℃, and the composite oxide powder is subjected to reduction carbonization reaction; when the reaction is finished, the vane centrifugal pump (19) stops rotating, the spiral rotary airflow stops moving at the moment, all the reacted powder of the partition plate (20) is opened and falls into the cooling box (31) under the action of gravity, and the cooled powder enters the material storage barrel (33), so that the final preparation process of reduction carbonization is finished.

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