CN118768062B - Production method for improving fluidity of inorganic mineral powder - Google Patents

Abstract

The present invention provides a production method for improving the fluidity of inorganic mineral powder, comprising the following steps: crushing the inorganic mineral raw material so that the crushing rate reaches more than 90%, then using gravity and buoyancy to grade and collect inorganic mineral powders of different particles, the collected powder A 100wt% particle size is less than 20 mesh, and it is returned to be combined with the inorganic mineral raw material for crushing, the collected powder B particle size is 20-120 mesh accounting for ≥80wt%, the powder C particle size is greater than 100 mesh accounting for ≥80wt%, and the mass ratio between powder B and powder C is controlled between (8:2) and (6:4); the powder C is further ground to a particle size greater than 300 mesh accounting for more than 80wt%, and mixed with the powder B. The present invention can improve the fluidity of inorganic mineral powder, and the production method is applicable to all inorganic mineral powders, such as the production of non-metallic mineral powders such as barium carbonate and barium titanate.

Description

Production method for improving fluidity of inorganic mineral powder

Technical Field

The invention relates to the field of inorganic mineral powder production, in particular to a production method for improving the fluidity of inorganic mineral powder.

Background

The inorganic mineral powder is mainly prepared from inorganic mineral raw materials in the nature, and can be divided into various types according to the difference of components and properties, such as quartz powder, talcum powder, calcium carbonate powder, wollastonite powder, mica powder and the like, and other non-metallic mineral materials such as common barium carbonate, barium titanate and the like belong to common inorganic minerals.

With the continuous progress of technology and the improvement of environmental awareness, the market demand of inorganic mineral powder is growing. In particular to the development of high-performance and environment-friendly products, the application prospect of the inorganic mineral powder is wider. In the future, with the continuous improvement of the preparation technology and the continuous discovery of novel inorganic mineral resources, the types and performances of inorganic mineral powder are more diversified, and the application field is further expanded.

The method for producing the inorganic mineral powder in the prior art mainly adopts a method of crushing and grinding, but the inorganic mineral powder produced by the traditional production method has the defects that the energy consumption of equipment is increased and the electricity consumption is also increased due to poor fluidity in the pipeline transportation process, the dosage of the matched agent in the production process is larger due to fluidity, the quality of the product cannot be maintained at a higher level, and the stability is also poor.

In view of this, the present invention has been made.

Disclosure of Invention

The invention aims at a production method for improving the fluidity of inorganic mineral powder, which improves the fluidity of the powder by controlling the particle size of the powder in the whole production method, reduces the energy consumption and the electricity consumption of equipment and the consumption of additives in the production process by improving the fluidity of the powder, and can achieve the effect of reducing the production cost for production enterprises. The production method is suitable for the production of all inorganic mineral powder, such as nonmetallic mineral powder of barium carbonate, barium titanate and the like.

In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:

The invention provides a production method for improving the fluidity of inorganic mineral powder, which comprises the steps of crushing inorganic mineral raw materials to enable the crushing rate to reach more than 90%, then grading and collecting inorganic mineral powder with different particles by utilizing gravity and buoyancy, wherein the 100wt% of the collected powder A is smaller than 20 meshes, returning the powder A to be combined with the inorganic mineral raw materials for crushing, the particle size of the collected powder B is 20-120 meshes and is more than or equal to 80wt%, the particle size of the powder C is more than 100 meshes and is more than or equal to 80wt%, and the mass ratio between the powder B and the powder C is controlled between (8:2) and (6:4).

The mesh size of the powder B and the powder C is very clearly defined, because if the particle size of the powder B is too large, the powder B cannot be perfectly filled when being mixed with the powder C later, gaps are generated, the fluidity is affected, and the particle size of the powder C cannot be too small, because if the particle size of the powder C is too small, the powder C can cause overfilling, the powder B is completely wrapped outside the flowing process, the fluidity of the powder B is reduced, the powder B is required to be in a proper particle size range, the powder C is required to be in a proper particle size range when being mixed, and the larger and better particle size of the preferred range is required to be in the whole powder, so that the particle size of the powder B is required to be 20-120 weight percent or more, the particle size of the powder C is larger than 100 weight percent or more, and the perfect proportion can be formed by mixing the two kinds of powder after the particle sizes are mixed, and the filling is also sufficient. The above parameters are also all the best ranges found after specific practice according to the types of various inorganic mineral powders. The powder C is further ground to a particle size of more than 300 meshes and a proportion of more than 80wt%, and the powder C is mixed with the powder B to achieve the aim of the invention.

The mass ratio between the powder B and the powder C needs to be controlled between (8:2) and (6:4), because the powder C can be fully filled into gaps of the powder B in the ratio, so that friction force among particles with the same particle size in the powder is reduced, if the large particle ratio is too high in the flowing process, the large particles can increase friction among the same particles, and small particles with a certain mass ratio are matched to fill the gaps of the large particles, the interactive friction is changed into rolling friction, but the matched amount needs to be proper, because perfect filling cannot be achieved no matter the large particles are too many or the small particles are too many, and the proper mass ratio between the large particles and the small particles is a great amount of creative labor, so that the optimal mass ratio range can be known only after a great amount of practice.

In the scheme of the invention, the powder is classified according to the particle size in the process of producing the inorganic mineral powder, and the prepared inorganic mineral powder has better fluidity by continuously searching the classification mode of the invention, because experiments show that after the powder C is ground to the particle size of more than 300 meshes, especially when the particle size ratio reaches more than 80wt%, the particle size difference between the powder C and the powder B is increased, and the fluidity of the whole inorganic mineral powder is improved by utilizing the ultralow friction force and viscosity of the powder C.

Preferably, as a further implementation scheme, the powder C is continuously ground to more than 80wt% and is between 350 meshes and 600 meshes. When 80wt% or more of the powder C is controlled to be within the range of 350-600 meshes, the fluidity improving effect is optimal, and of course, the range means that the particle size range cannot be too large or too small, because if the powder C is too large in particle size, friction force and viscosity cannot be optimally expressed, the powder C cannot have the effect after being mixed with the powder B, and when the powder C is too small in particle size, the powder C is too fine in particle size, friction force among particles in the powder is increased, and too many particles with the same particle size can reduce the fluidity.

Preferably, as a further implementation scheme, in the process of classifying by utilizing gravity and buoyancy, the powder is firstly divided into 5 components by adopting an accelerating jet flow mode for blanking, and then the powder of different components is continuously sieved according to the mesh granularity to obtain powder A, powder B and powder C so as to improve the accuracy of the particle size distribution of the powder in the whole process.

Because the accuracy is not high if the powder A, the powder B and the powder C are obtained by direct screening, and the accurate control of the particle size ratio and the mass ratio between the powder cannot be realized, the invention adopts a mode of screening out 5 components first, and the 5 components are in a way of enabling the parameters of the accelerated jet to be in certain correspondence with the particle sizes of the components by the accelerated jet, so that the particle sizes of the 5 components screened out are controlled within an expected range.

Preferably, as a further implementation scheme, the jet rate of the accelerated jet is adjusted by fixing the jet air quantity and adjusting the jet pressure of 150-300KPa, so that the accelerated jet is divided into 5 components according to the particle size by different jet rates, wherein the particle size of a first component is smaller than 20 meshes, the particle size of a second component is 20-40 meshes, the particle size of a third component is 40-100 meshes, the particle size of a fourth component is 100-200 meshes, and the particle size of a fifth component is larger than 300 meshes.

The above scheme is that the particle sizes of the five components are obtained by controlling the injection pressure within a certain range, so that the injection pressure is changed within the range.

Preferably, as a further embodiment, the particles between the first component and the second component smaller than 20 mesh are mixed to obtain powder a, the particles of the second component larger than 20 mesh, the particles of the third component smaller than 120 mesh are mixed to obtain powder B, and the remaining fourth component and fifth component are mixed to obtain powder C. The above 5 components are precisely distributed into powder A, powder B and powder C by a material distributing valve.

Through the mode of firstly dividing into 5 components, then mutually mixing to respectively form powder A, powder B and powder C, the process can ensure that the particle size of the powder B is 20-120 meshes with the particle size of more than or equal to 90wt%, the particle size of the powder C is more than 100 meshes with the particle size of more than or equal to 90wt%, the mass ratio between the powder B and the powder C is controlled between 7.4:2.6, which is equivalent to further improving the particle size of the powder B and the ideal particle size of the powder C, and can further achieve the aim of improving inorganic mineral powder. Since the larger the powder ratio in the preferred particle size range is, the better the filling property after the subsequent mixing is, the more sufficient the filling is, the better the natural improvement of fluidity is, so the ratio of the particle size distribution of the powder B to the powder C can be controlled more accurately by the way of screening 5 components first.

Preferably, the jet air volume of each stage is fixed to be 20000Nm ³/h, when the primary stage jet pressure is controlled to be 300-350KPa, the particle size of the first component is smaller than 20 meshes, and the particle size of the second component is 20-40 meshes;

Controlling the jet pressure of the second fraction to be 200-230KPa to obtain the particle size of the third fraction to be 40-100 meshes;

The third stage graded spraying pressure is controlled at 150-180KPa, the grain diameter of the fourth component is 100-200 meshes, and the grain diameter of the fifth component is more than 300 meshes. The optimum spray pressure for each component has finally reached a quantified result through a number of inventive practices, so that by controlling a certain spray pressure the desired particle size of the component can be obtained accordingly.

The invention also provides production equipment for improving the fluidity of the inorganic mineral powder, which comprises a raw material bin and a crusher connected with the raw material bin, wherein the crusher is connected with an air classifier for classifying crushed powder, and the bottom of the air classifier is correspondingly provided with a material bin A for collecting the powder A, a material bin B for collecting the powder B and a material bin C for collecting the powder C;

The storage bin C is sequentially connected with a first kneader and an ultrafine grinder, the storage bin B is connected with a second kneader, and the ultrafine grinder is connected with the second kneader to be used for mixing ground powder C with powder B.

The whole production process flow of the invention is as follows:

The raw materials are stored through a raw material bin, then fall into a belt metering scale to convey and meter weight by utilizing the action of gravity, a crusher adjusts the rotating speed according to the falling materials, a hammer head arranged on a rotary table is accelerated to drive to rotate at a high speed by utilizing the ultra-high rotating speed of the rotary table of the crusher, the hammer head rotating at the high speed is used for beating the raw materials falling from top to bottom, the raw materials are beaten by the hammer head rotating at the high speed and then are crushed and rebound back to an impact plate of an inner barrel of the crusher for secondary crushing, then fall under the action of gravity, are beaten and repeated again by a second layer of hammer head, and finally fall under the action of gravity and are crushed into powder.

The powder obtained in the powder preparation process enters a feeding end of an air classifier under the action of gravity, the air classifier is divided into three stages, each stage blows in a fixed amount of air (nitrogen or carbon dioxide can also be used for screening the dropped powder), the speed of the accelerated jet is controlled by adjusting the pressure of the accelerated jet, and therefore, the powder dropping positions are different due to different particle sizes of the powder, the powder drops into different bins according to different weights, at the moment, a bin A for collecting the powder A at the bottom of the air classifier and a bin B for collecting the powder B are arranged between the bin C for collecting the powder C, and a first bin to a fifth bin are arranged between the bin C for collecting the powder C, so that the powder with different particle sizes is collected by the five bins.

Therefore, the larger the weight is, the smallest the powder jet distance is, the more easily the powder falls on the left bin position of the air classifier, the more easily the lighter powder falls on the right side of the air classifier, the lightest powder enters the dust remover along with the airflow, and the discharging falls into the last bin. The air classifier can adjust the blowing pressure of the fan to select powder according to the load of materials from the crusher and the self requirement, and can sequentially classify all the powder according to the particle size.

After the first bin to the fifth bin are classified, the first bin to the fifth bin can go to the lower three bins through a bin discharging valve and a pipeline, namely bin A, bin B and bin C. Wherein the powder in the storage bin A is unqualified powder, the powder is returned to the crusher for secondary crushing, the powder collected in the storage bin B is 20-120 meshes with the proportion of more than or equal to 80wt%, and the powder collected in the storage bin C is more than 100 meshes with the proportion of more than or equal to 80wt%. The mass ratio of the total powder B to the powder C is controlled between (8:2) and (6:4).

And in the grinding process, the powder C in the bin C is weighed by a discharging valve and a weighing device, then is forcedly mixed and stirred uniformly with the metered water at the first kneader, and is sent to a superfine grinding machine for superfine grinding, so that the particle size of the powder C is reduced to more than 300 meshes and more than 80 weight percent, and the powder C is mixed with the powder B. The process improves the fluidity of the inorganic mineral powder, and the investment and the energy consumption of the inorganic mineral powder prepared by the method are reduced by more than 30 percent for production enterprises.

Compared with the prior art, the invention has the beneficial effects that:

(1) The production method actually improves the fluidity of the inorganic mineral powder, and the method for controlling the particle size of the powder in the whole production method improves the fluidity of the powder, thereby reducing the energy consumption and the electricity consumption of equipment and the consumption of additives in the production process and achieving the effect of reducing the production cost for production enterprises;

(2) The production equipment for improving the fluidity of the inorganic mineral powder has simple process and convenient operation, and the inorganic mineral powder prepared by the production process has good fluidity, so that the production efficiency is practically improved, and the production cost is reduced.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:

FIG. 1 is a specific process flow diagram of a production method for improving fluidity of inorganic mineral powder according to example 1 of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, which will be understood by those skilled in the art, for illustrating the present invention only and should not be construed as limiting the scope of the present invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

As shown in fig. 1, spodumene mineral is exemplified and implemented, and the whole process is divided into a crushing stage, a powder selecting stage and a grinding stage;

And in the crushing stage, spodumene is stored in a raw material bin, coal is dropped on a belt scale with a metering function through a raw material discharging valve and is conveyed to the position right above the crusher, and the coal is dropped into a feeding hole of the crusher under the action of gravity. After spodumene falls into the crusher, the rotation speed is modulated to 70-80%, the linear speed is controlled to 120m/s, spodumene particles are beaten and crushed by a hammer head rotating at high speed, and the spodumene particles rebound to a rebound impact plate of the inner liner of the crusher again for secondary crushing. Then falls downwards under the action of gravity, enters a two-layer hammer head to strike, rebounds to the impact plate again, the breaking rate reaches more than 90%, and the unqualified material A (with the particle size of more than 20 meshes) is only 5-8%. The rotational speed is increased to 90%, the linear speed is increased to 140m/s, the unqualified material A (the grain diameter is larger than 20 meshes) is only 2-6%, the rotational speed is further increased to 100%, the linear speed is increased to 160m/s, and the unqualified material A (the grain diameter is larger than 20 meshes) is only 1-3%. It can be seen from the above adjustment that as the rotational speed increases, the total amount of reject a (particle size greater than 20 mesh) decreases, that is, the return ratio decreases further as the rotational speed increases. Therefore, different materials select proper rotating speeds, in addition, the higher the rotating speed is, the larger the abrasion is, and the service life of the hammer head can be shortened along with the increase of the rotating speed.

In addition, the rotation speed of the crusher is increased by 100%, and the feeding amount is increased to the full load of the equipment. At this time, the return ratio is relatively increased, i.e., the reject material is increased. The rotational speed is finally selected to be 70-80% most suitable after multiple times of debugging, and the material returning ratio is smaller than 5%.

In the powder selecting stage, crushed materials enter an air classifier by gravity to carry out classified screening, the fixed three-stage jet air quantity is 20000Nm ³/h, and when the primary classified jet pressure of the air classifier is controlled to be 300-350KPa, a first component and a second component are obtained. And when the secondary stage injection pressure of the air classifier is controlled to be 200-230KPa, a third component is obtained, and when the tertiary stage injection pressure of the air classifier is controlled to be 150-180KPa, a fourth component and a fifth component are obtained. The components with different particle sizes (weight) respectively fall into a bin 1, a bin 2, a bin 3, a bin 4 and a bin 5, the particle size distribution of each bin is shown in a table 1 after analysis, the numerical values shown in the table 1 are sieving rates corresponding to the particle sizes, for example, the bin 5 can be more than 300 meshes and can occupy 92.04%, and other bins can also know the specific particle size distribution from specific sieving rate records.

Sieving rate of 15 bins

The materials in the bin 1 and part of the bin 2 enter the bin A and are returned to the crusher. The materials of part of the bin 2, the bin 3 and part of the bin 4 enter the bin B, the materials of part of the bin 4 and the bin 5 enter the bin C, the proportion of B to C is just 7.4:2.6, the particle size of the powder B is 20-120 meshes and is more than or equal to 90wt%, and the particle size of the powder C is more than 100 meshes and is more than or equal to 90wt%.

According to the data of the particle size analysis, the total average particle size of the bin C does not meet the requirement, further grinding is needed, and particularly the material of the bin C is ground to a large extent, and finally more than 90wt% of particles are larger than 300 meshes. The bin C is subjected to weighing and metering, the mixed solution is stirred and mixed uniformly at the first kneader, and then the mixed solution is sent to an ultrafine grinder for further deep grinding, so that powder C with the granularity of more than 300 meshes and the proportion of more than or equal to 90wt% is obtained.

And in the mixing stage, the ground powder C is conveyed to a second kneader after being metered, and is mixed and stirred with the powder B which is fed from the storage bin B and is metered to obtain spodumene mineral powder. The friction coefficient was 0.09, the apparent viscosity was 302, the analytical particle size distribution was as shown in specific table 2, and the values shown in the table are the sieving rate corresponding to the particle size.

TABLE 2 sieving rate of product powder

8 Mesh (%)	20 Mesh (%)	40 Mesh (%)	100 Mesh (%)	200 Mesh (%)	300 Mesh (%)
						100	99.8	94.5	50.2	46.6	40.5

Through the particle size distribution, the transition of the particle size distribution to two polarization can be obviously seen, namely, the particle size difference between mineral powder is enlarged, the friction force between the same particle sizes is reduced, and the fluidity of the inorganic mineral powder is improved.

Based on example 1, the following groups 1 to 3 were set to compare the parameter transformations of example 1, and the specific setting and detection results are shown in the following detailed embodiments of groups 1 to 3 and tables.

Group 1

The specific procedure was as in example 1 above, except that the ratio between powder B and powder C was 1:1.

Controlling the solid content of the product powder to 65%, measuring the friction coefficient to be 0.5, and analyzing the particle size distribution to obtain the particle size distribution of the product powder by mixing analysis to be shown in table 3, wherein the numerical values shown in the table are the sieving rate corresponding to the particle size.

TABLE 3 sieving rate of product powder

8 Mesh (%)	20 Mesh (%)	40 Mesh (%)	100 Mesh (%)	200 Mesh (%)	300 Mesh (%)
						100	100	94.5	92.2	70.1	59.5

Group 2

The specific operation steps are the same as in example 1 above, except that 60wt% of the particle size of the powder C after further grinding is 350 to 600 mesh, and 40wt% is 600 mesh or more.

The solid content of the product powder is controlled to 65%, the friction coefficient is measured to be 0.32, the apparent viscosity is 561, the particle size distribution of the product powder is shown in table 4 after mixing analysis, and the numerical value shown in the table is the sieving rate corresponding to the particle size.

TABLE 4 sieving rate of product powder

8 Mesh (%)	20 Mesh (%)	40 Mesh (%)	100 Mesh (%)	200 Mesh (%)	300 Mesh (%)
						100	99.7	95.2	57.9	50.6	47.5

Group 3

The specific procedure was as described above for example 1, with the first and second components being obtained when the air classifier stage one stage injection pressures were controlled between 350 and 400 KPa. And when the jet pressure of the second stage of the air classifier is controlled between 250 and 280KPa, a third component is obtained, and when the jet pressure of the third stage of the air classifier is controlled between 200 and 230KPa, a fourth component and a fifth component are obtained, five different particle size components are obtained, wherein the particle size distribution is shown in table 5, and the numerical values shown in the table are the sieving rates corresponding to the particle sizes.

Sieving rate of 55 bins

	8 Mesh (%)	20 Mesh (%)	40 Mesh (%)	100 Mesh (%)	200 Mesh (%)	300 Mesh (%)
							Stock bin 1	80	50	0.00	0.00	0.00	0.00
Stock bin 2	100	97.02	89.21	0.00	0.00	0.00
							Stock bin 3	100	99.02	97.31	95.43	0.00	0.00
Stock bin 4	100	100	100	99.02	89.21	10.00
							Stock bin 5	100	100	100	100	100	96.34

The solid content of the product powder is controlled to 65%, the friction coefficient is measured to be 0.47, the apparent viscosity is measured to be 652, the analysis particle size distribution is that the particle size distribution of the product powder obtained through mixing analysis is shown in table 6, and the numerical values shown in the table are sieving rates corresponding to the particle sizes.

TABLE 6 sieving rate of products

8 Mesh (%)	20 Mesh (%)	40 Mesh (%)	100 Mesh (%)	200 Mesh (%)	300 Mesh (%)
						100	99.8	95.1	52.9	56.2	61.5

Group 4

The spodumene mineral is used as an example for implementation, and the preparation process of the original inorganic mineral powder is adopted, namely spodumene stored in a raw material bin is dropped on a belt scale with a metering function through a raw material discharge valve, and is conveyed to the position right above a crusher, and is blanked into a crusher feed inlet by utilizing the gravity effect. After spodumene falls into the crusher, the rotation speed is modulated to 70-80%, the linear speed is controlled to 120m/s, and spodumene particles are beaten and crushed by a hammer head rotating at high speed;

The crushed spodumene mineral is directly ground by using primary grinding equipment (ball milling) and mixed liquid, after grinding into powder, various parameters of the product are detected, the solid content of the product powder obtained by the original powder grinding process is found to be 59 percent on average, and the friction coefficient Wei is measured to be 0.89, and the apparent viscosity is found to be 900.

The parameters of friction coefficient, viscosity, etc. for each of the above examples and groups 1-4 are summarized in Table 7 below:

TABLE 7 detection results

From the above analysis of experimental data, comparison of example 1 with each group can lead to the following conclusions:

(1) In comparison with group 1, the ratio of powder B to powder C is not controlled within the range required by the solution of the present invention, so that the good effect of improving the fluidity of the mineral powder, especially the compressibility and the friction coefficient, cannot be achieved, and the reason is that the ratio of powder C in group 1 is too high, resulting in a uniform distribution of powder B and powder C, failing to achieve a filling state between particles, failing to reduce the friction between particles in the powder.

(2) In comparison with group 2, the particle size distribution of powder C is not controlled within the range required by the scheme of the invention, and the good effect of improving the fluidity of the mineral powder is not achieved, especially the friction coefficient is affected, because the powder C in group 2 is ground too finely, so that the gaps among the particles of powder B are excessively filled by the material C, and the friction force among the particles in the powder is increased.

(3) In comparison with the group 3, in the embodiment 1, since the spraying pressure of each air classification is not controlled within the range required by the scheme of the invention, the five particle size components cannot be divided into corresponding particle sizes according to the preset requirement, so that the particle size distribution of the follow-up powder B and powder C is further influenced, the particle sizes of the powder B and the powder C are increased, gaps between particles of the powder B and the powder C cannot be fully filled, and the friction force among particles in the powder is increased, and therefore, the good effect of improving the fluidity of mineral powder cannot be achieved.

In summary, by comparing example 1 with the corresponding parameters of group 1, group 2 and group 3, it can be seen that in the solution of the present invention, it is very important to strictly control the proportions and particle size distribution of the materials B, C, since only then can the materials C be fully filled into the inter-particle gaps of the materials B, so as to reduce the friction between the particles, and finally achieve the purpose of improving the flowability of the inorganic mineral powder.

While particular embodiments of the present invention have been illustrated and described, it will be appreciated that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims (1)

1. A production method for improving fluidity of inorganic mineral powder, which is characterized by comprising the following steps:

Crushing inorganic mineral raw materials to enable the crushing rate to reach more than 90%, then grading and collecting inorganic mineral powder materials with different particles by utilizing gravity and buoyancy, wherein the 100wt% of the collected powder material A is smaller than 20 meshes, returning to be combined with the inorganic mineral raw materials again to crush, the particle size of the collected powder material B is 20-120 meshes accounting for more than or equal to 80wt%, the particle size of the powder material C is larger than 100 meshes accounting for more than or equal to 80wt%, and the mass ratio between the powder material B and the powder material C is controlled between (8:2) - (6:4);

continuously grinding the powder C until the particle size is more than 300 meshes and the weight ratio is more than 80%, and mixing with the powder B;

In the classifying process by utilizing gravity and buoyancy, the powder is firstly divided into 5 components by adopting an accelerating jet flow mode for blanking, and then the powder of different components is continuously sieved according to the size of the mesh granularity to obtain powder A, powder B and powder C so as to improve the accuracy of the particle size distribution of the powder in the whole process;

The jet rate of the accelerated jet is adjusted by fixing the jet air quantity and adjusting the jet pressure of 150-300KPa, so that the accelerated jet is divided into 5 components according to the particle size by different jet rates, wherein the particle size of a first component is smaller than 20 meshes, the particle size of a second component is 20-40 meshes, the particle size of a third component is 40-100 meshes, the particle size of a fourth component is 100-200 meshes, and the particle size of a fifth component is larger than 300 meshes;

Mixing the first component and the second component with particles smaller than 20 meshes to obtain powder A, mixing the second component with particles larger than 20 meshes, the third component with particles smaller than 120 meshes to obtain powder B, and mixing the rest fourth component with the fifth component to obtain powder C;

fixing the jet air quantity of each stage to 20000Nm ³/h, when the jet pressure of the first stage is controlled to 300-350KPa, obtaining the particle size of the first component to be less than 20 meshes, and the particle size of the second component to be 20-40 meshes;

Controlling the jet pressure of the second fraction to be 200-230KPa to obtain the particle size of the third fraction to be 40-100 meshes;

the third stage graded spraying pressure is controlled at 150-180KPa, the grain diameter of the fourth component is 100-200 meshes, and the grain diameter of the fifth component is more than 300 meshes.