JPS5916806B2 - Method and apparatus for adding cohesive powder in a fluidized bed blender - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the formulation of UO2 and second cohesive powders using a fluidized bed mixer, and in particular to homogeneous blending of solid UO2 powder and second cohesive powders. and an improved method and apparatus for converting the mixture into a mixture.

BACKGROUND ART Mixing of powder and granular materials has conventionally been carried out by various methods.

Various types of mechanical mixers have been used, such as tumbler mixers, ribbon mixers, and high shear mixers, as well as spouting bed blenders and fluidized bed blenders. In the prior art, UO2 powder is mainly mixed in mechanical tumbler type mixers. This type of mixer was not satisfactory in obtaining mixed batches that met UO2 powder homogeneity specifications. Failure to meet homogeneity specifications is believed to be due to the presence of stagnation or immobile areas within the fluidized bed of components being mixed in the mixer and separation problems during discharge. U.S. Patent No. 416 to LarsOn et al., assigned to the present applicant.
No. 8914 discloses an improved bubbling fluidized bed blender. The Larson et al. blender eliminates the large immobile area of conventional bubbling fluidized bed blenders and includes a fluidizing grid at the bottom as a housing for the heterogeneous powder to be mixed, preferably UO2 powder. A vertical plank-shaped mixing container is provided. A fluidization grid constructed in accordance with the teachings of Larson et al. consists of an array of generally downward pyramid-shaped hoppers each having walls that converge into a conical opening. A plurality of gas orifices are provided to direct a flow of fluidizing gas upwardly into the bottom of each hopper. Fluidizing gas is fed into each orifice at a sufficient rate to cause bubbles of fluidizing gas to rise into the powder mixture and out of the powder, thus mixing the powders until a homogeneous mixture of powders is obtained. The combination of an in-line array of hoppers and an upwardly directed gas orifice eliminates the immobile areas found in conventional bubbling fluidized bed blenders. However, conventionally known devices for mixing fine cohesive powders in a fluidized bed blender include UO,
There is no effective equipment to meet product homogeneity specifications when compounding the powder and a second powder mixture that differs over a wide range of physical properties.

More specifically, due to their cohesive properties, some types of secondary
The powder mixture quickly forms large agglomerates, which impairs dispersibility. Additionally, some low density agglomerates undesirably separate from the main UO2 powder in the fluidized bed blender due to stagnation or immobile regions present at the bottom of the fluidized bed. Furthermore, the gas flow rate used to introduce the second powder mixture causes variations in powder mixing. The present invention utilizes an improved fluidized bed blender, an improved vortex mill, and an eductor all interconnected by a common pneumatic conveying system.

A fluidized bed blender comprises a vertical mixing vessel in which a fluidizing grid is arranged at the bottom. The fluidization grid consisted of an array of pyramid-shaped hoppers, each hopper at its base designed to receive fluidization gas and to inject a jet of fluidization gas upwardly along the wall of each hopper in a diverging swirl pattern. It has one group of orifices. At least one impingement device considering a deflection plate is arranged above the array of pyramidal hoppers adjacent to the base of the fluidized bed in the mixing vessel. The mixture of the second powder component and the gas is introduced under pressure into the impingement device, and the deflection plate directs the second powder component into the turbulent fluidized bed of UO2 powder previously introduced into the vertical mixing vessel. Distribute evenly. In this specification, the term [second material]
, "-second powder material" or "second powder component" means the second
The material, the second powder material or the second powder component is ? This is to be understood to mean that mixtures of hydrophobic, hydrophilic or hygroscopic materials as mentioned may be constituted and may contain additional ingredients such as binders. Furthermore, the second material, second powder material or second powder component may be a single additive such as a hydrophobic, hydrophilic or hygroscopic material to be mixed homogeneously with the UO2 powder. a mixture of a second powder component and a gas;
It is transported from the volute mill to the collision device at a predetermined pressure.

In this mixture, the second powder component is a relatively large agglomerate (approximately 1200 microns), and the vortex mill
The mixture of powder component and gas is received at a predetermined pressure and the particles of the second powder component are pulverized to an average particle size of about 10 to 60 microns, preferably about 15 microns. A mixture of the second powder component and gas is fed from the eductor to the volute mill at a predetermined pressure.

The eductor has a material feed inlet, a gas inlet port for pressurizing the system, and an internal mixing chamber. The mixing chamber of the eductor initially coarsely mixes the components of the P1 second powder mixture by the action of turbulence caused by the flow of inert gas supplied therein at a predetermined pressure. The crude mixture is then pneumatically conveyed from the eductor to a volute mill under pressure. The particles are pulverized in a vortex mill and further mixed. Next, the second powder mixture is supplied from the volute mill to the collision device at a predetermined pressure, thereby introducing the second powder mixture into the fluidized bed blender at a predetermined pressure and uniformly dispersing it, so that it is homogeneously mixed with the UO2 powder in the blender. do. In order that the invention may be better understood, it will be described below in conjunction with the drawings. FIG. 1 shows one embodiment of the powder mixing apparatus of the present invention.

The device basically consists of three main parts: an improved fluidized bed blender 10, an improved swirl mill 11} and an eductor 1.
Consists of 2. The mixing of the UO2 powder and the second powder component (which, as previously described, can be a powdered hydrophobic, hydrophilic or hygroscopic material) is carried out in a modified fluidized bed blender 10 as shown in FIG.

As shown in FIG. 2, fluidized bed blender 10 consists of a vertical mixing vessel 13 having a fluidizing grid 14 at its bottom. The fluidizing grid 14 consists of an array of pyramid-shaped hoppers 15, as shown in FIG. Each hopper 15 has a group of orifices 16 at its bottom, as shown in FIG. It is set up to do so. The fluidizing gas jet establishes a boiling or bubbling layer of the UO2 powder 9 initially charged into the mixing vessel 13. Above the array of pyramidal hoppers 15, at least one impingement device 20 including a turning plate 21 is arranged, as shown in FIGS. In Figures 3 and 5, the collision device 20 is
It is configured in the form of a cage-like structure designed to provide a deflecting effect (or baffle effect) and a turning effect to the mixture of gas and second material that is fed under pressure into the fluidized bed blender.

Specifically, the collision device 20 includes a turning plate 21 and an upper plate 22. The turning plate and the top plate are circular and are held vertically spaced apart by circumferentially spaced columns 23 . Top plate 22 has a central hole in which it is secured to conduit 24 by suitable means. Via a device arranged in this way, the mixture of the second powder component and the gas described above is introduced into the blender vessel and thus into the fluidized bed of UO in the vessel. Upon entering the container, the second powder component hits the deflection plate 21 under pressure and receives a deflecting effect, so that the second powder component is uniformly distributed in the UO2 fluidized bed 9 in the container along the circumference of the impingement device. Ru. In addition, conduit 24 structurally supports impingement device 20 in position within the fluidized bed near its bottom. Although one collision device is illustrated and described, a plurality of collision devices may be arranged in a row above the hot spring 15 and used. Referring to FIGS. 1 and 4, conduit 24 is connected to outlet 25 of said volute mill 11, so that the mixture of gas and second powder material is passed from volute mill 11 to conduit 25.
4.

Vortex mill 11 receives a mixture of second powder material and gas from eductor 12 at control inlet 26 . Agglomerate the mixture powder and granules in a spiral mill 11 (approximately 1200 microns).
The mixture is milled to a mixture with an average particle size of about 10 to 60 microns, preferably about 15 microns. After the second powder component mixture has been milled to a suitable particle size, it is transported under pressure from the volute mill 11 via conduit 36 to the impingement device 20 shown in FIGS. 3 and 5. As shown in FIG. 1, the second powder component mixture is pneumatically transported from the eductor 12 to the vortex mill 11 under a pressure a. In order to draw the second powder component mixture from the opening 34 into the eductor 12 under vacuum, the action of the gas introduced into the eductor through the artificial hole 33 is utilized.

The gas introduced into the eductor 12 is an inert gas such as N2, and is supplied by a gas source 37 as shown in FIG. The second powder component mixture is transferred from the eductor 12 to the vortex mill 11
Pneumatically pump it to the FIG. 3 shows one of the plurality of hoppers 15 included in the fluidized bed blender 10 in conjunction with an impingement device 20 located within the blending chamber. The fluidized bed blender 10 used in the present invention is of a type well known in the art and includes a vertical mixing vessel 1 having a fluidizing grid 14 at the bottom.
Includes 3. The fluidization grid 14 consists of an array of generally downwardly directed pyramid-shaped hoppers 15, the walls of each hopper converging into a conical opening. multiple valves 17
are provided for discharging the mixed powder, e.g. UO2 powder and the second powder mixture, from the hopper, each valve 17 being located at the bottom of each hopper 15. At the base of each hopper 15 is a group of orifices 16 connected by a manifold and connecting pipes to a gas port 18 leading to a source of fluidizing gas. A comprehensive description of considerations for the design of conventional bubbling fluidized bed blenders, including considerations of particle properties, particle size, particle size distribution, vessel geometry, surface gas velocity, and circulation patterns. ``Fluidization hexagram and particle fluid system'' by Frederick Zenz hexagram and Donald Osma.
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The fluidized bed blender of the present invention is distinguished from conventional fluidized bed blenders by the arrangement of at least one impingement device 20 above the fluidization grid, as shown in Figures 2 and 3.

Although only one impingement device is shown, a series of impingement devices may be used in practicing the invention.

The collision device 20 has a cage-like structure as shown in Figures 3 and 5, and includes an inlet conduit 24, a circular turning plate 21, a circular upper plate 22, and a support that connects the upper plate and the turning plate in a vertically spaced relationship. It has a member or support 23. The particular construction of the impingement device is such that this device has a deflecting effect on the second powder mixture entering there under pressure from conduit 24 so that the second powder mixture enters the second powder mixture under pressure and is thus introduced into the mixing chamber of the fluidized bed. The second
The ingress velocity and pressure of the powder mixture is reduced. When the pulverized second powder mixture enters the fluidized bed blender from the vortex mill, the second powder mixture becomes UO2 due to the action of the collision device.
It is widely distributed within the powder, thus resulting in a homogeneous powder mixture. In Figures 1 and 4, a second powder mixture is fed into the volute mill 11 through its inlet 26 and fed into the feed load 27.
Go through it to get inside.

The five-bearing system of the volute mill is adapted for high pressure (>10 psig) operation, allowing the gas and second powder material to be injected under pressure into the lower region of the fluidized bed blender.
More specifically, if the bearing system of the vortex mill is adapted for high pressure operation, it is possible to provide a high velocity flow to the pneumatic transport system O, which transfers the TLK gas and the second powder material to the fluidized bed blender. This prevents the finely pulverized second powder material from becoming agglomerated and clumped during transportation. As the second powder mixture passes through the feed load 27 of the swirl mill 11, it contacts the spreader 30 at the base of the centrifugal rotor assembly.

When the second powder mixture contacts the surface of the spreader 30, the particles are accelerated to about 213 m/sec by the centrifugal action of the rotor rotating at about 20,000 rpm. The particles are propelled radially outward through a groove 28 defined by the lower spreader and the upper rotor plate and into a tungsten carbide impingement block 32 located near the circumference of the lower spreader 30. collide with great force. Upon impact with the tungsten carbide impingement block 32, the particles of the second powder mixture are comminuted and then pumped from the volute mill via pressurized conduit 36 to the fluidized bed blender 10. It should be noted that the second powder particles can be pulverized using any suitable pulverizing mill, and the present invention is not limited to the use of a spiral mill. As shown in FIG. 1, the eductor 12 is of conventional design, having a material feed inlet 34, a gas inlet 33, and an internal mixing chamber.
The components of the second powder mixture are initially mixed in the mixing chamber under the effect of turbulence by a flow of inert gas entering therefrom from the gas source 37.

As mentioned above, the particle size of the second mixture is on the order of about 1200 microns. The eductor 12 also provides the pressurization of the line system 36 necessary for the operation of the entire mixing device. Eductor outlet 35
is directly connected to the inlet hole 26 of the swirl mill 211 by a conduit system 36, thus delivering the initial blend of the second powder mixture to the swirl mill 11 as schematically shown in FIG. The details of the eductor 12 described above do not constitute any part of the present invention, and the eductor 12 is used to introduce the second material into the mixing device.
5. Any suitable type can be used as long as it can be introduced initially, and in the embodiment of the present invention, Type 26 manufactured by Attack Inc. (AMETKI Inc., Cornwells Heights, Pennsylvania, USA) is used.
Use 4. 3. The mixing device of the present invention is effective for homogeneously mixing powders with widely different physical properties with UO2 powder in a fluidized bed blender. In operation, the vessel 13 of the bubbling fluidized bed blender is filled with UO and powder from the inlet at the top of the vessel. At the entrance at the top of the container
Four valves, for example butterfly valves, are provided to prevent powder from escaping during the mixing process. Butterfly valves do not form any part of the invention; any suitable type of valve may be used. The container 13 is filled to approximately half its height with a mixture of heterogeneous, ie unmixed, powders.
The lower half of the vessel 13 thus functions as the mixing chamber of the vessel, while the upper half functions as a gas plenum in which powder entrained by the fluidizing gas settles. Mixing of the particles in this type of blender is accomplished by injecting bubbles of fluidizing gas from a set of orifices 16 located at the base of the vessel and maintaining the vessel at an internal pressure of about 1 to 5 psig. .

The fluidizing gas bubbles rise from the orifice through the fluidized bed in a comprehensive zigzag motion to the top of the fluidized bed. When a bubble is formed, adjacent particles flow along the top of the bubble and down into the void below, thus causing the bubble to rise.

The particles directly above the bubble are pushed upwards, the rest are pushed aside, and some of them flow down and into the bottom of the bubble, filling the bubble path. The rising bubble thus spreads the particles radially in all directions. As a given bubble rises, the particles filling its bottom void become slightly more densely packed than those immediately adjacent to the bubble's path. The next bubble rising in its vicinity passes through a path connecting the less densely packed particles immediately adjacent to the path of the first bubble. Each successive bubble thus tends to rise at a separate location, mixing previously mixed particles with other particles. As more and more bubbles rise up the particle bed, neighboring small bubbles join together to form dense bubbles. This coupling action, combined with the tendency of the bubbles to flow towards areas of lower pressure, creates a wide area zigzag bubble motion to achieve horizontal and vertical convective mixing. Bubbles escaping from the top of the particle bed scatter some UO2 powder into the gas plenum at the top of mixing chamber 13. However, the compressed gas blows out from the particle bed intermittently. During such intermittent gas blowing, particles that would normally be entrained in the gas stream fall back into the particle bed rather than being entrained by the perturbation gas and being dispersed. It should be emphasized here that in the bubbling fluidized bed blender described above, although the cyclical mixing described above occurs, there is virtually no mass movement of the particle bed as is present in the erupted bed blender. After the initial mixing of the second powder mixture in the eductor,
The mixture entrained by the inert gas is conveyed under pressure to the supply port 26 of the swirl mill 11 and further into the interior of the swirl mill via the feed load.

After passing through the feed load 2r of the volute mill, the second powder mixture impinges on the surface of a spreader 30 having a pyramidal nipple-shaped central protrusion and gradually descending outwards. The surface of the spreader 30 cooperates with an upper rotor plate 31 through which the feed load 27 passes. The rotor plate surface faces the spreader surface and defines a radial groove 28 therebetween, which groove 28 gradually narrows near a circular impingement block 32 located along the outer circumference of the rotor plate and the spreader. It has an outer peripheral outlet. Spretsuda 30 rotates at approximately 20,000 rpm,
This rotational force, in combination with the input pressure of the conduit system, forces the second particle mixture, entrained in the inert gas, into the radial groove 28 and the second particle mixture into the tungsten carbide impingement block 32 at approximately 213 m/sec. of the particles of the second powder mixture, thereby reducing the particle size of the particles of the second powder mixture to about 12
00 microns to an average diameter of about 5-60 microns, preferably about 15 microns. Improved spiral mill 11
The second powder mixture after being reduced to a suitable micron diameter is in a form suitable for mixing with the UO2 powder in the modified fluidized bed blender 10.

The second powder mixture, entrained by an inert gas, exits the swirl mill 11 via the discharge means 25 shown in FIG.
to the inlet 24 of the impingement device 20.

The second powder component mixture enters the fluidized bed blender 10 through an impingement device 20 located near the base thereof, preferably about two feet above the top of the grid 14, ie, downward pyramidal hopper 15. The second powder mixture is applied to the inlet 24 of the impingement device 20 at about 3 to 5 psig.
It preferably enters at about 3.5 psig and hits turning plate 21.

The cage-like structure of the impingement device 20 provides a deflection effect and, in conjunction with the turning plate, reduces the pumping force so that the second powder mixture enters the fluidized bed blender 10 at a pressure of approximately 2 psig. The impingement device serves to uniformly distribute or disperse the second powder mixture into the fluidized bed of the first powder component within the fluidized bed blender. The process of mixing the second cohesive powder with the UO powder begins by starting the eductor 12, which pressurizes the second powder mixture conduit 36 and the vortex mill 11.

Almost simultaneously, the fluidized bed blender 10 is started to randomly circulate the UO2 powder that has entered the fluidized bed blender.
First start the eductor 12 and
Prevents O2 powder from flowing back through the impingement device 20 into the pneumatic conduit system 36. After starting the edakume 12 by injecting an inert gas, such as N2, at a pressure of about 25 psig into the gas inlet 33, the pre-chilled second powder mixture is introduced into the eductor's material feed inlet 34 at about the same time. The second powder mixture is free from turbulence caused by internal gas flow.
and is drawn into an internal mixing chamber for coarse mixing under the action of an internal pressure of less than about 5 psig.

The second material to be mixed is generally hydrophobic, hydrophilic or hygroscopic. Since these second materials have the property of agglomerating, they tend to form agglomerates with poor dispersibility. Hydrophobic materials such as zinc stearate, oils, fats and waxes are not soluble in water but adhere to each other.

Therefore, when mixing this type of material, proper dispersion can only be achieved after reducing the size of the agglomerates. Hydrophilic materials tend to absorb water and bind it together.

Ingredients such as carbohydrates (starches, vegetable gums, etc.) and complex proteins fall into this category. Proper mixing of these materials can only be achieved after size reduction as well. Inorganic materials including ammonium bicarbonate, ammonium oxalate, calcium chloride, and zinc chloride constitute the third category labeled hygroscopic.

These materials absorb moisture from the dog's air. More specifically, deliquescent materials are hygroscopic powders of water-soluble chemical salts that dissolve in water absorbed from the atmosphere. These materials are difficult to handle and must be supplied dry. The second powder mixture coarsely mixed in the eductor is approximately 1 to 3 ps
ig1 is pneumatically conveyed, preferably at a pressure of about 2 psig, to a vortex mill where it is milled to the desired particle size v.

The pressure increases by approximately 2 psig due to the action of the vortex mill;
As a result, the pressure to convey the mixture from the swirl mill to the mixing vessel is initially slightly higher. Thereafter, as previously described, the pulverized second powder mixture is pneumatically pumped into the impingement device of the fluidized bed blender, which cooperates with a bubbling bed of the main or first powder mixture, in this example UO2 powder. to achieve homogeneous mixing of the first and second powder mixtures. Once homogeneous mixing of the UO2 powder and the second powder mixture is achieved, the homogeneous mixture is discharged from the hopper through a plurality of valves. A valve is placed at the opening of each hopper to provide an outlet for the mixing vessel after achieving homogeneous mixing of the powder. After completion of the mixing process, the mixed powder was transferred to the AdOmitis, assigned to the applicant.
U.S. Pat. No. 4,182,383 of S) et al. Other embodiments and uses of the invention will occur to those skilled in the art, and the invention encompasses all such modifications.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the apparatus of the present invention including a fluidized bed blender, a swirl mill, and an eductor; FIG. A front view showing a fluidized bed blender having the device; FIG. 3 is a sectional view of the fluidized bed blender taken along the line 3-3 in FIG. 1;
Figure 4 is an expanded longitudinal sectional view of the spiral mill shown in Figure 1, Figure 5 is an expanded sectional view of the collision device shown in Figure 3, and Figures 6 and 6 are lines 6-6 in Figure 4. FIG. 10...Fluidized bed blender, 11...Vortex mill, 12...Eductor, 13...
Container, 14... Fluidization grid, 15...
・・・Hotsupa, 16... Orifice, 17...
...Valve, 18...Gas inlet, 20...
・Collision device, 21... Turning plate, 22...
・Top plate, 23... Support column, 24... Conduit, 25... Spiral mill outlet, 26... Spiral mill inlet, 30...・Spretsuda, 28...
...Groove, 33...Gas inlet, 34...
・Material supply port, 35...Eductor exit, 36・
... Conduit system.

Claims (1)

[Claims] 1. A method for blending a powder component mixture, comprising the following steps:
(a) introducing the first powder component into the pressure container; (b)
establishing a fluidized bed of the first powder component within the container; (c) introducing a second powder component into the container under pressure;
A step of uniformly dispersing the second powder component in the fluidized bed by colliding the second powder component with a turning plate disposed within the fluidized bed. 2 (a) pulverizing the second powder component mixture in a pulverizing mill; (b) transporting the pulverized second powder component mixture from the pulverizing mill to the pressure container under pressure;
c) impinging the pulverized second powder component mixture on a turning plate disposed within the fluidized bed of the first powder component and uniformly dispersing the second powder component mixture into the first powder component mixture in the container; A method for blending a mixture of powder components according to claim 1, comprising the step of blending the first and second powder mixtures homogeneously. 3. (a) introducing gas into the eductor and starting pressurization; (b) then adding a second powder component mixture to the eductor; (c) introducing the gas and the second powder component mixture into the eductor. (d) conveying the gas and the second powder component mixture under pressure to the pulverizing mill and pulverizing the second powder component mixture in the mill;
(e) conveying a gas and pulverized second powder component mixture from the pulverizing mill to the pressure vessel under pressure;
) impinging the pulverized second powder component mixture on a turning plate disposed within the fluidized bed of the first powder component and uniformly dispersing the second powder component mixture into the first powder component mixture in the container; A method for blending a mixture of powder components according to claim 1, comprising the step of homogeneously blending the first and second powder mixtures. 4. The first powder component is UO_2 and the second powder component is a hydrophobic, hydrophilic or hygroscopic powder material, (a) introducing the powder UO_2 component into a pressure container, (b) introducing the powder into the pressure container. establishing a fluidized bed of powder UO_2 components;
(c) introducing said second powder component into said container under pressure, said second powder component being introduced into said fluidized bed by impinging said second powder component on a turning plate disposed within said fluidized bed; 4. The method according to any one of claims 1 to 3, comprising the step of uniformly dispersing. 5 The second powder component has a concentration of about 10 when introduced into the fluidized bed.
Claim 4 having an average particle size of ~60 microns
The method described in section. 6 The second powder component has a particle size of about 15% when introduced into the fluidized bed.
6. A method according to claim 4 or 5, having an average particle size of microns. 7 (a) initiating a fluidized bed of a first powder component in the pressure vessel at a vessel pressure of about 1 to 5 psig;
(b) introducing a second powder component into said vessel at a pressure of about 3 to 5 psig, wherein said second powder component impinges on a turning plate disposed within the fluidized bed; (c) said impingement turning plate; The deflection and dispersion effect reduces the pressure of the second powder component to approx.
psig and uniformly dispersing the second powder component in the fluidized bed. 8 (a) pulverizing the second powder component mixture in a vortex mill; (b) transporting the pulverized second powder component mixture from the vortex mill to the pressure vessel at a pressure of about 3.5 psig; (c) ) The finely pulverized second powder component mixture is added to the first
The second powder component mixture is uniformly dispersed into the first powder component mixture in the container by impinging on a turning plate disposed in a fluidized bed of powder components, thereby dispersing the first and second powder components.
8. A method according to any one of claims 1 to 7, comprising the step of homogeneously blending the powder component mixture. 9 (a) Introduce the gas into the eductor and
(b) introducing a second powder component mixture into the eductor; (c) introducing gas and the second powder component mixture into the eductor for about 5 psig; (b) introducing a second powder component mixture into the eductor;
(d) mixing the gas and the second
The powder component mixture is transferred from the eductor to a vortex mill for about 1 to 3 minutes.
psig pressure and pulverizing the second powder component mixture in the vortex mill; (e) gas and pulverizing the second powder component mixture;
The powder component mixture is transferred from the vortex mill to a pressure container at approximately 3 to 5 ps.
(f) impinging the pulverized second powder component mixture on a turning plate disposed within the fluidized bed of the first powder component, thereby reducing the pressure to about 2 psig;
Dispersing the second powder component mixture into the first powder component mixture in the container under this pressure to homogeneously blend the first and second powder component mixtures.
The method described in any of Item 8. 10 (a) conveying a gas and a second powder component mixture from the eductor to a volute mill at a pressure of about 2 psig, and pulverizing the second powder component mixture in the volute mill;
10. The method of claim 9, including the step of: ) conveying the gas and finely divided second powder component mixture from the vortex mill to a pressure vessel at a pressure of about 3.5 psig. 11 (a) a vertical pressure-resistant mixing vessel; (b) means for introducing a first powder component into said mixing vessel; (
c) a fluidization grid establishing a fluidized bed within said mixing vessel; (d) at least one impingement device disposed above said fluidization grid and having a turning plate; means for introducing the second powder component under pressure into the impingement device and applying it to the turning plate, thereby uniformly dispersing the second powder component in the fluidized bed of the first powder component in the mixing vessel; A fluidized bed mixing device comprising: 12. The collision device is formed by connecting a circular upper plate and a lower plate which are vertically spaced apart by a plurality of struts arranged at intervals along the circumference thereof, and the circular lower plate constitutes the turning plate. An apparatus according to claim 11. 13 (a) conduit means for introducing the second powder component into the impingement device and applying the second powder component to the upper central surface of the turning plate; and (b) conduit means for introducing the second powder component into the impingement device and directing the second powder component to the upper central surface of the turning plate; 13. Apparatus according to claim 11 or 12, further comprising support means arranged on the support means. 14 further comprising pressurized pulverizing means for receiving a mixture of gas and powder components under pressure and pulverizing and mixing the powder components; 14. A device according to any of claims 11 to 13, comprising means for transporting. 15: (a) an eductor; (b) means for introducing gas under pressure into said eductor; (c) means for introducing powder material into said eductor; (d) an internal mixing chamber for mixing said gas and powder material; 15. The apparatus of claim 14 further comprising: (e) outlet means for delivering said gas and powder material to said comminution means. 16 (a) a vertical mixing vessel with a fluidization grid disposed at the bottom; (b) a cage mounted within said vertical mixing vessel and comprising an inlet for delivering a gas-carrying powder material mixture therein under pressure; collision device. (c) conduit means for conveying the gas and powder material mixture under pressure to the inlet of said impingement device; (d) a volute mill useful for high pressure operation, the volute mill being capable of conveying the gas and powder material mixture under pressure from the vortex mill to the mill; (e) an inlet for receiving a gas and powder material mixture under pressure, and means for mixing and comminution of the introduced powder material; (e) Eductor, having a material feed inlet, a gas inlet, an internal mixing chamber for initial mixing of the gas and powder material mixture, and an outlet (
f) conduit means connecting the eductor outlet and the swirl mill inlet and conveying the gas and powder material mixture under pressure from the eductor to the swirl mill; and (g) means for pressurizing the device in a predetermined manner. 16. An apparatus according to any one of claims 11 to 15.