Method for forming homogeneous blends of particulate materials

Claim 3

The method of claim 1 wherein said agitation and shear forces acting on said slurry are produced by passing said slurry through a disperser-comminutor comprising a rotor turning at high speed within a stator.

Claim 4

The method of claim 2 wherein said rotor and stator each comprise an open ended cylinder having an outer surface and an inner surface and a slotted wall.

Claim 5

The method of claim 3 wherein said rotor and stator are dimensioned such that there is a small shearing gap between the outside surface of the rotor and the inside surface of the stator.

Claim 6

The method of claim 2 wherein the rotational speed of said rotor is such as to produce a circumferential velocity from about 5 to 25 meters per second.

Claim 8

The method of claim 6 wherein said polymer is a rubber and wherein said mixture includes carbon black.

Claim 9

The method of claim 1 wherein said mixture comprises a polymer and a salt.

Claim 10

The method of claim 1 wherein said mixture includes a ceramic.

Claim 11

The method of claim 1 wherein said mixture includes a material which is normally liquid, said liquid freezing and forming solid particulates in said liquid nitrogen.

Claim 12

The method of claim 1 wherein liquid nitrogen is removed from said homogeneous suspension by vaporization.

Claim 13

A batch-to-continuous process for compounding mixtures of unlike particulate materials comprising: preparing a batch of said unlike materials by mixing a predetermined quantity of each of said materials together and suspending said materials as a slurry in liquid nitrogen to form a slurry batch; subjecting said slurry batch to agitation and shear forces to break up agglomerates and to maintain individual particles of said materials in a randomly mixed, homogeneous suspension; transferring said homogenized slurry batch to a holding means, said holding means arranged to maintain the homogeneity of said suspension and to prevent settling of particulates; continuously withdrawing a slurry stream from said holding means and stabilizing said withdrawn slurry stream by removing liquid nitrogen therefrom to form a powder; preparing a second slurry batch having the same composition as said first slurry batch and subjecting said second batch to agitation and shear forces to break up agglomerates and to maintain individual particles of said materials in a randomly mixed, homogeneous suspension to obtain a second homogenized slurry batch; transferring said second homogenized slurry batch to said holding means at a time before said first slurry batch has been exhausted by withdrawal of said slurry stream therefrom, and continuing the preparation of slurry batches at a rate sufficient to provide a continuous slurry stream for stabilization by removal of liquid nitrogen therefrom to form a powder.

Claim 14

A batch-to-continuous process for compounding mixtures of unlike particulate materials comprising: preparing a batch of said unlike materials by mixing a predetermined quantity of each of said materials together and suspending said materials as a slurry in liquid nitrogen to form a slurry batch; subjecting said slurry batch to agitation and shear forces to break up agglomerates and to maintain individual particles of said materials in a randomly mixed, homogeneous suspension; transferring said homogenized slurry batch to a holding means, said holding means arranged to maintain the homogeneity of said suspension and to prevent settling of particulates; continuously withdrawing a slurry stream from said holding means and stabilizing said withdrawn slurry stream by removing liquid nitrogen therefrom to form a powder; preparing a second slurry batch having the same composition as said first slurry batch and subjecting said second batch to agitation and shear forces to break up agglomerates and to maintain individual particles of said materials in a randomly mixed, homogeneous suspension to obtain a second homogenized slurry batch; transferring said second homogenized slurry batch to said holding means at a time before said first slurry batch has been exhausted by withdrawal of said slurry stream therefrom, and continuing the preparation of slurry batches at a rate sufficient to provide a continuous slurry stream for stabilization by removal of liquid nitrogen therefrom to form a powder.

Claim 15

The method of claim 12 wherein said agitation and shear forces acting on said slurry are produced by passing said slurry through a disperser-comminutor comprising a rotor turning at high speed within a stator.

Claim 16

The method of claim 13 wherein said rotor and stator each comprise an open ended cylinder having an outside surface and an inside surface and a slotted wall, said rotor and stator dimensioned such that there is a small shearing gap between the outside of the rotor and the inside of the stator.

Claim 17

The method of claim 14 wherein the rotational speed of said rotor is such as to produce a circumferential velocity from about 5 to 25 meters per second.

Claim 18

The method of claim 12 wherein said unlike materials comprise a rubber and carbon black.

Claim 19

The method of claim 12 wherein said unlike materials comprise a polymer and a salt.

Claim 20

The method of claim 12 wherein said unlike materials include at least one material which is normally liquid and which freezes to form solid particulates in liquid nitrogen.

Claim 21

The method of claim 12 wherein said holding means comprise a plurality of holding tanks, each of said holding tanks sized to hold a slurry batch.

Claim 22

The method of claim 19 wherein each of said holding tanks is adapted to provide agitation sufficient to maintain said slurry in suspension.

Claim 23

The method of claim 20 wherein a measured quantity of a particulate solid is introduced into each said slurry batch in said holding tanks.

Claim 24

The method of claim 21 wherein said particulate solid is a physically fragile material.

Claim 25

The method of claim 22 wherein said fragile material comprises a fiber.

Claim 26

The method of claim 12 wherein liquid nitrogen is removed from said slurry stream by vaporization.

Claim 27

The method of claim 24 wherein said vaporization is accomplished in a conveyor having heat transfer capability.

Claim 28

The method of claim 12 wherein said stabilized powder is subjected to further processing to form a shaped article.

Claim 29

The method of claim 26 wherein said further processing comprises extrusion.