US3028103A - Method and apparatus for comminuting materials - Google Patents

Description

R. P. FISHER April 3, 1962 METHOD AND APPARATUS FOR COMMINUTING MATERIALS 4 Sheets-Sheet 2 Filed Sept. 18, 1957 INVENT OR. R use? P. F/Sl/E/Q ATTORNEYS April 3, 1962 R. P. FISHER 3,028,103

METHOD AND APPARATUS FOR COMMINUTING MATERIALS Filed Sept. 18, 1957 4 Sheets-Sheet 3 r a I I i I v '5 5"? Q '3' a I I I 4 Ii. a

' 1| HI. 'I \M U N h x i 1L E 4 INVENTOR. 2 KME T P Ema 4110 ENE 7 April 3, 1962 R. P. FISHER 3,028,103

METHOD AND APPARATUS FOR COMMINUTING MATERIALS Filed Sept. 18, 1957 4 Sheets-Sheet 4 FIG.7.

RVBHT'R United States Patent ()fiice spasms Patented Apr. 3, 1962 3,928,103 METHOD AND APPARATUS FOR COMMINUTING l'tlATERlALS Robert P. Fisher, Los Angeles, Calif., assignor toMl croson Equipment Corporation, a corporation of Deltaware Filed Sept. 18, 1957, Ser. No. 684,677 17 Claims. (Cl. 241-5) My invention relates to a new and improved method and apparatus, which can be used to work or comminute solid materials and liquids and for many other purposes. The invention also includes certain comminuted solid materials, as new articles of manufacture.

Hitherto, the size of solid objects or particles has been decreased by the action of mechanical force, asin many types of mills, which have operated by a mechanical rubbing or grinding or crushing action; or in the micronizer type of apparatus, in which jets of steam or air impinge upon the particles and cause said particles to whirl about and shatter each other.

According to one embodiment of my invention, a column or stream of air is mixed with solid pieces or particles of starting material, and said mixture is moved in a selected direction which is conveniently designated as the forward direction. Said forwardly moving mixture is caused to impinge upon a member, which creates air vortices and/ or compressural waves in said forwardly moving air. The kinetic energy of these air vorticcs and/or air waves, combined with the kinetic energy of said forwardly moving stream or column of air, has sufficient kinetic energy to exert a shearing or disintegrating action upon the solid pieces or particles of starting material in order to reduce their size, independently of the usual mechanical action of a mill. These vortices and/or air waves may be directed in a direction which is transverse to the selected forward direction of movement of the mixture. In a preferred embodiment of the invention, but without limitation thereto, the stream or column of air, intermixed with the solid pieces or particles of the starting material, is given an original rotary forward movement about an axis of rotation, thus moving the mixture by centrifugal action in an original forward circular direction which has an outwardly directed radial component, and also has a forward circumferential component which is much greater than said outward radical component. This mixture of air and solid particles is moved towards a discharge zone or outlet end of the apparatus. The outward radial movement of the ejected mixture, beyond said outlet end, is limited by a circumferentially disposed confining surface, which is provided with a vortex-creating member which is transverse to said forward circumferential component. This vortex-creating member projects inwardly of said confining surface, namely, towards the axis of rotation. A layer of compressed air of said stream or column of air is maintained at said confiningsurface. This layer protects said confining surface against abrasion. 'lhe forwardly moving, ejected mixed stream contacts with or impinges upon the front face of said vortex-creating member. A layer of compressed air of said ejected, forwardly moving stream or column of air is maintained at said front face, to protect said vortex-creating member against abrasion. A series of air vortices are generated at said front face by the kinetic energy of the forwardly moving ejected stream or column of air. These air vortices move into said column or stream in a directionwhich is opposed to said outward radial movement. These air vortices generate compressural air waves in said column, up to its inlet end. The kinetic energy of these vortices and air waves in said rotating stream or column, combined with the kinetic energy of the rotating stream or column, shears or disintegrates the solid pieces or particles anterior the outlet end of said stream or column, to reduce the size of said solid pieces or particles anterior saidoutlet end, especially if these solid pieces or particles have a crystalline structure.

The same principle can be used to work liquids or mixturesof liquids, even without reducing the .size of any solid material. Also, liquids or mixtures. of liquids can be worked without mixture with air or any gas or vapor. I can thus, as one example, reduce the size of pieces or particles of solid material, without abrading the apparatus, and without/the usual mechanical milling action.

When solid pieces or particles of ores are reduced in size in a mill bya mechanical rubbing or grinding or pounding or crushing action, the reduced pieces or particles have blunt and rounded edges. According to one example of this invention, if the starting material is an ore, the worked or com-minuted pieces or particles of said ore have particles of the valuable metalliferous material which have clean and sharp edges, which evidences the absence of such mechanical milling action. Providing the worked pieces or particles of an ore with such clean and sharp edges is a great advantage, because it enables easy and large separation of the valuable metalliferous ingredients of an ore from the valueless ingredients thereof. The invention includes worked solid materials which have such sharp and clean edges, as a new product.

Also, in working pieces or particles of solid material in order to decrease their size, in a mill which operatcs'me-' chanically by rubbing or grinding or pounding or crushing, the parts of the mill are abraded by the working. This abrasion is objectionable, because it shortens the life of the mill. Also, the abraded material of the mill contaminates the worked material. Such contamination is highly objectionable, especially if the worked solid material must have a pure color, such as talc, uncalcined kaolin, calcined kaolin, titanium dioxide, and many other pigment materials.

In many cases, a crude ore can be directly worked according to this invention, without crushing or other preliminary treatment of the crude ore. After the pieces or particles of the crude ore have been reduced in size according to this invention, the comminuted crude ore is then treated so as to separate its valuable metalliferous material from the valueless impurity.

In other cases, if preliminary crushing of the crude ore is required, in order to get pieces or particles of suitable initial size, this is done. The crushed pieces or particles are then comminuted according to this invention, and the comminuted material is then treated to separate the valuable metalliferous material from the valueless impurity.

This makes it possible to' eliminate the usual steps of concentrating an ore, prior to comminution.

Thus, an iron ore which is poor in iron may be thus comminuted, and the valuable metalliferous material can then be easily and effectively separated by magnetic action from the valueless impurities. This can be done much more easily than in treating an ore which is merely crushed or otherwise mechanically treated in the usual manner, prior to concentration by magnetic separation or other separation method.

Without limitation thereto, and merely as one example, the invention can be embodied in an apparatus of the type shown in Lykken US. Patent No. 1,756,253 dated April 29,1930; and in Lykken U.S. Patent No. 1,838,560, dated December 29, 1930.

For convenience, the improved apparatus is designated as a mill, although its pioneer principle and method of operation is Wholly different from that of each and every prior mechanical comminuting apparatus of the type which is usually designated a a mill.

In the type of mill which is illustrated in said Lykken' patents, a rotor is provided with rotor-blades or rotorvanes, in order to provide tapered spaces or columns between said rotor-blades. Said rotor and its blades are rotated within a casing. Each tapered space or colunin has an inlet end which is spaced from and is proximate to the axis of rotation of the rotor. Each tapered space or column has an outlet end which is spaced from and is proximate to the inner wall of the casing, which is the confining wall in this example. tated about its rotor-axis, centrifugal action creates a higher air pressure at the outlet end of each tapered space or column than at the inlet end of each tapered space or column. In said type of mill, the comrninution of solid material has resulted in rapid abrasion of the casing, the rotor, and the rotor-blades. The rapid abrasion of the inner wall of the casing and the rotor' has greatly shortened the life of said mill. The abrasion of the rotorblades is less objectionable, because these blades or vanes are relatively inexpensive and can be replaced.

By means of the improved method and apparatus disclosed herein, the abrasion of the casing, rotor, rotorblades and other parts of the apparatus, is negligible, if any, at suitable high rotor speed. At relatively low rotor speed, there may be some abrasion of the rotor-blades, but'there is no substantial abrasion of the casing and rotor. As above noted, the abrasion of the rotor-blades is a minor disadvantage, because said rotor-blades are relatively inexpensive and can be easily replaced. In the highly preferred form, the rotor is operated at suitable high rotor speed, in order to protect the casing, rotor, and rotor-blades against abrasion. In a less preferred form of the invention, the casing and rotor are protected against substantial abrasion, but the rotor-blades may be subject to some abrasion.

Y The inner wall of the casing in the illustrated embodiment has vortex-creating members at the face of said inner wall. These vortex-creating members extend inwardly from said inner wall, towards the axis of rotation of the rotor. These vortex-creating members create vortices in the fluid or in the fluid part of the material which is Worked in the improved apparatus. The fluid may be liquid at ordinary room temperature of 20 C.-30 C., or said fluid may be air, or any gas or a vapor.

In the best embodiment of the illustrated apparatus, the blades are shaped to provide spaces or columns which have a plurality of different cross-sections from their inlet ends towards their outlet ends. As one example, each said column has a first section of uniform cross-section at its inlet end, and a succeeding second tapered section whose cross-section increases towards said outlet end, and the space or column is further enlarged at the outer end of said second section, to provide each said space or column with a third section of maximum cross-section.

In the illustrated embodiment, the clearance between the outer tips of said rotor-blades and the part-cylindrical inner wall of the casing is selected, depending upon the rotor speed. The clearance between the outer tips of said rotor blades and said vortex-creating members is also selected, depending on said rotor speed.

These respective clearances may be increased, as rotor speed is increased. Preferably, the clearance between the inner wall of the casing and the vortex'creating memhers is equal to the clearance between the tips of the rotor blades and said vortex creating members, or said clearances are substantially equal.

Due to centrifugal action, the material in each said column or space is moved radially outwardly in each column or space, towards the inner wall of the casing. Also, the mate-rial in each column or space is forwardly circumferentially actuated.

For convenience, it is assumed that a mixture of air and solid. input material is fed into the apparatus.

In such case, the rotor is rotated at the selected rotor speed, in order to create a uniform condition of the air in the respective columns or spaces, before feeding the solid input rrraterial into the apparatus, and a mixture of When the rotor is robetween adjacent vortex-creating members.

air and solid input material is fed into the apparatus after said uniform condition of the air has been created and while said uniform. condition of the air is maintained during the comminution, so that the air in each column or space is continuously provided with the vortices and air-waves.

The forward circumferential velocity of the material in each column or space, greatly exceeds the outward radial velocity of the material which is caused by the centrifugal action in each column or space. Hence the material which is ejected from the'outlet end of the column Or space has a velocity whose forward, circumferential component greatly exceeds its outward radial component.

Considering the initial period in which only air is fed into the apparatus, the proper coordination of rotor speed and of said clearances will result in ejecting respective separate veins of air from the respective spaces or columns, and said ejected veins of air will thus have a movement which has said smaller velocity of said radial component and said greater velocity of a forward circumferential movement. By proper coordination of the necessary factors, a compressed layer of air will be maintained at each section of the inner wall of the casing, Each said vortex-creating member has a front impinged face, namely, the face which is impinged by the respective forwardly moving mass of air which is ejected from the respective column or space. A layer of compressed air will be maintained at each said front impinged face. Also, by coordinating the necessary factors, a series of vortices will be created in the air, at each said front impinged face. These air vortices will be directed and moved inwardly in each column or space, toward the axis of rotation of the rotor. These air vortices will create a violent air turbulence in the air of each column or space, together with compressural air waves of high frequency and high kinetic energy. By selecting suitable high rotor speed, some of these air waves which are generated in said column, or even a major ratio of said air waves, will have a frequency above the average audible limit of 9,000 cycles per second, and even above the supersonic frequency of 20,000 cycles per second.

This air turbulence and these air waves, in combination with the circumferential air velocity in the columns or spaces, will exert their eflect up to the inlet ends of the columns or rotor-blades, and even in the entire inlet Zone or space between said inlet ends. The inlet of the casing, which is at the axis of rotation of the rotor, may be made sufiiciently small to prevent the kinetic energy of said tubulence and of said air waves, from escaping out of said inlet of the casing.

During the cornminution or other working, each of the columns is continuously provided with air vortices and compressural waves. As a result, the comminution or other working is completed, substantially before the material is ejected from the outlet ends of the columns. In any event, such comminution or Working is substantially completed anterior the protective layer of air or other fluid which is maintained at the confining Wall or confining surface. When material is fed into the apparatus, one of the spaces or columns is in communication with the discharge zone of the apparatus. The comminution or other working is completed in this space or column, prior to ejection of the contents from this space or column.

If solid material is thus worked, the comminuted solid material will not excessively abrasively contact with the confining surface or inner wall of the casing, because this is prevented by the protective layer of compressed air or liquid which is maintained at said inner wall. This protective layer may be stationary or substantially stationary. Also, such protective layer is maintained at the front impinged face of each vortex-creating member, thus protecting said member against abrasion. The only flow or the main flow of the material which is ejected from the outer ends of the columns, will be in the form of a stream which flows forwardly and circumferentially, inwardly of the inner ends of the vortex-creating members. The compressed layer of air or fiuid which is maintained at the front impinged faces of the vortexcreating member will discharge a series of vortices of .12. :1 liquid or other fluid, and these vo-rtices will travel in each column towards the axis of rotation, thus creating turbulence and compressural waves in each column, between its outer end and in its inner end, and even in the common input space between the inner ends of the columns and rotor-blades.

By properly selecting the factors, the rotor is substantially protected against abrasion, because the input solid particles are moved radially into the respective columns or spaces, before abrasively contacting with the rotor. In the best form, and as above noted, the rotor-blades are also protected against any perceptible abrasion.

Tests have been made with a test mill which embodies the invention, in which the vortex-creating members or bars have been t mporarily removed, thus providing corresponding recesses in the inner wall of the casing. When these bars were removed, there was rapid abrasion of the inner wall of the casing and also of the rotor of the test mill. Also, with said bars in position in said test mill, the comrninuted particles were of substantially uniform size and had good sharp and clean edges.

When said bars were removed from the test mill, there was much greater irregularity in the particle size of the comminuted particles, and said comminuted particles did not have such sharp and clean edges to a desirable extent; and there was considerable and undesirable irregular variation in the results of using the test mill.

As above mentioned, a mixture of pieces or particles of a crude, metalliferous ore and air can be worked in the improved apparatus, in order to comminute said pieces or particles. In some cases, the valuable metalliterous material'of the crude ore consists of one or more compounds or a metal, such as zirconium oxide, copper sulfide, and other valuable metallic compounds. In other cases, the valuable metalliferous material consists of a native metal in uncombined, elemental form, such as native gold, native platinum, native silver, native cop- 'per, native arsenic, native bismuth and other native metals. in every case, the crude ore, in addition to valuable metalliferous material, contains valueless gangue impurities, exemplified by quartz, silica, feldspar, and other impurities.

The tests with a test mill have resulted in the following novel and pioneer results:

(A) At suitable high rotor speed, beginning with 7,000 to 8,000 revolutions per minute, the abrasion of the caslag, and of the vortex-creating bars, rotor and rotorblades, it there was any abrasion, was negligible, even though the initial particles of said crude ores which were fed into the test mill, could readily abrade the unhardened steel of said casing, bars, rotor and rotor-blades, if the connninution of said coarse particles in the mill resulted solely from mechanical grinding action or other mechanical milling action. 7

(ll) The comminution of said crude ores resulted in a mixture of particles of the valuable metalliferous material or materials with the particles of the impurities of the respective crude ore. These crude ores were fed into the test mill without any preliminary concentration or other treatment, save that in some cases, said crude ores were crushed.

When this mixture of comminuted particles was examined under the microscope, such examination showed that the valuable comminuted particles of the valuable metalliferous material, including the particles of native metal, were pure and were not contaminated with the valueless material. Also, the comminuted particles, including the particles of the native metal, had sharp and clean and sharply defined edges, which proved the absence of mere mechanical grinding or mechanical milling action. If the sole elfect was mechanical grinding or milling action, this would result in comminuted particles which had round and blunted edges. This clean separation olf valuable particles from valueless particles, and the sharp and clean edges of the valuable particles, makes it possible to secure a much larger recovery of the valuable particles of this mixture by any method, such as by the well-known flotation method and the well-known concentration by tabling. In tabling, the ore, mixed with water, is flowed over rifiies, which retain the separated valuable particles. In the well-known flotation method, the crude ore is crushed. The crushed, crude ore is mixed with water, to which a suitable oil has been added. The mixture of crude crushed ore, water and oil, is agitated to incorporate air into said mixture, to form a froth. The valuable particles float on the bubbles of said froth. By means of the improved method, it is possible greatly to increase the recovery of the valuable particles by either the flotation or tabling method. In one of the tests with the test mill later described, the crude ore was a crude patinum ore which had native platinum. This crude platinum ore was crushed to initial large particle size without any other preliminary treatment, and a mixture of air and said initial large particles was worked in the test mill. The comminuted crude platinum ore was then concentrated by the old and primitive method of panning, in which the comminuted platinum ore was washed with water in a shallow pan, in order to separate a concentrate of the comminuted, crude platinum ore. T he concentrate which was thus secured from the comminuted mixture, showed particles of native platinum which could be easily mechanically separated. This is a wholly novel and pioneer result, because it has hitherto been deemed impossible. In all prior practice, native platinum has been collected from a crushed, crude platinum ore concentrate by an expensive chemical process, which resulted in a large loss of the native platinum. The original, crude platinum ore which was treated in crushed form in the test mill had a large percentage of gangue, and assayed at a value of only $64.00 per ton. The concentrate which was secured by said primitive panning process from the comminuted, crude platinum ore had a value of $2,000.00 per ton. The original, tiny particles of native malleable platinum in the original crushed, crude platinum ore had been aggregated to larger size by the working in the improved mill. The invention is therefore of great value in working other crude ores which have malleable native metals, as exemplified by native gold, native silver, native copper, and others. The in vention is also of great value for Working sulfide ores, as

tellurium ores, and other ores.

(C) The color of the commiuuted crude ore which was produced in the test mill was always diiierent from the color of the original, coarse particles of crude ore which Were fed into the test mill. The changed color was darker than the original color. The comminuted crude ore had a grey tone or grey color, in comparison to said original color. This darkening usually increased with higher rotor speed, which resulted in more air vortices of greater kinetic energy and more air waves of high frequency and high kinetic energy. This darkening or other change in color, the substantial lack of abrasion of the test mill, and the sharp and clean edges of the valuable particles, and other results later reported herein, prove that at suitable high frequency the test mill generates compressural waves of super-sonic or superaudible frequency, and of suitable high kinetic energy. Page 371 of Electronics Dictionary by Cooke and Markus, published in 1945 by McGraw-Hill Book Company, Inc, defines superaudible as having a frequency above the range of audio frequencies, namely, above approximately 20,000 cycles per second; and defines superaudio frequency as a frequency above that of audible sound, namely, above approximately 20,000 cycles. it is diiricult, and even probably impossible, to measure the frequency of the vortices and compressural air waves which are generated by t. e mill in the rotating column or columns of air which are created in the mill, said waves being transmitted radially in said rotating column or columns of air and through the solid particles in said rotating column or columns of air.

(1?) The drawings herein disclose an embodiment of the invention which has two units. Each of said units 1s larger than the test mill which had a single unit or casing, with a single rotor therein. Since certain relative dimensions are important, FIG. 7 shows dimensions marked in inches. FIG. 7 is a to scale, which is twothirds of the actual size of each of the two units of the two-unit mill illustrated herein. FIG. 7 shows the horizontal rotor-axis 14a of the respective rotor and four rotor-blades or vanes 15a. The test mill also embodies the invention. In order to explain the tests which 2 have been made with the test mill, a preliminary explanation of said test mill is stated.

FIG. 7 shows that the inner wall C of the casing has a radius of six inches or substantially 150 millimeters. The inner wall C of the test mill has a radius 05 3.812 inches, or substantially 95 millimeters.

FIG. 7 shows three of the vortex-creating, cylindrical and identical bars R. As shown in FIG. 3, the casing has five such identical vortex-creating bars R, which are unequally angularly spaced and are located at stations 12b12c-12d-12e-12f. The outer part of each bar R fits closely, either rotatably or non-rotatably, in a partcylindrical recess RA, which has a diameter of one inch or substantially millimeters.

The rotor is rotated around its axis 14c in the forward direction of arrow 39. Each bar R has an innermost line RB which is parallel to axis 14c, a front impinged face RF and a rear face RE. The innermost lines RB are defined by the circular line RS, which is concentric with rotor-axis 14c. The clearance between bars R and the inner wall C is 0.406 inch or substantially 10.15 millimeters. The test mill has five identical vortex-creating bars, which are also unequally angularly spaced in the single casing at said stations 12b-12c12d-1.2e-12f. Each said bar of the test mill is of rectangular cross-section, and each said bar has parallel outer and inner flat faces, which are parallel to the respective tangent to circle RS. As measured in the direction of the respective tangent, the dimension of each flat outer and inner face is 0.5 inch or about 12.5 millimeters. Each said bar has two parallel fiat faces which are perpendicular to said outer and inner fiat faces. As measured in said perpendicular direction, the dimension of each said perpendicular face is five-sixteenths of an inch or substantially 8 millimeters. The outer part of each said bar of the test mill fits closely in a respective recess of wall C. The clearance between the inner wall of the casing of said test mill and the inner flat face of each bar is one-eighth of an inch or substantially 3.125 millimeters or 3,125 microns. The circle RS is tangential to such inner fiat faces.

FIG. 7 shows a minimum clearance of 0.031 inch or substantially 0.775 millimeter between the innermost lines R3 of bars R and the outer end-walls of the rotorvanes or rotor-blades 15-15(2. This clearance is usually and preferably up to three-eighths of an inch or substantially 9,375 millimeters, which is substantially equal to the clearance of 10.15 millimeters between wall C and bars R. In the test mill, the clearance between said endwalls 30 and the inner flat faces of the vortex-creating bars is one-eighth of an inch, which is equal to the clearance between said inner flat faces and said inner wall of the single casing of the test mill, which is exemplified by wall C.

In FIG. 7, each rotor-blade 1515a has an inner apex edge 29, which is at a radial distance of 0.937 inch or substantially 23.4 millimeters from rotor-axis 14c. In the test mill, this distance is 0.750 inch or substantially 18.25 millimeters.

In FIG. 7, the radial distance between edge 15b and circle RS is 3.625 inches or substantially millimeters. if the clearance between circle RS and end-wall 30 is in creased to the preferred clearance of three-eighths of an inch, this dimension is decreased to substantially 3.3 inches or substantially 82 millimeters.

In Phil. 7, each rotor-blade 15-15a has two planar faces 150 which are perpendicular to each other and which meet at the apex edge 29. These planar faces extend to edge 15b. The length of each planar face 150, as measured from the apex edge 29 to edge 15b is 1.415 inches or substantially 35.375 millimeters.

in FIG. 7, the distance between the parallel planar faces 15d and 15 of each rotor-blade 15-15a is two inches or substantially 50 millimeters.

in PEG. 7, the distance between the parallel faces 15a and 15a of each rotor-blade 1.5-15a is 0.750 inch or substantially 19.25 millimeters. In the test mill, this dimension is 0.5 inch or substantially 12.5 millimeters.

Since the rotor-blades of the test mill have the relative shape shown in the drawings, the disclosure of the test mill is clear. In FIG. 7, if the radial clearance between circle RS and end-walls 30 is three-eighths of an inch, the radial distance of each end-wall 30 from rotor-axis 14c is 5.219 inches or substantially millimeters. Hence, when a rotor-blade 15i5a is rotated through a complete revolution, its end-wall 30 is moved in a circle whose length is substantially 0.82 meter. Hence, if the rotor of the mill shown in the drawings is rotated at 4,000 revolutions per minute, each end-wall 30 is moved in a circular path substantially at the speed of eleven thousand feet per minute or substantially 3,300 meters per minute.

In the test mill, since the radius of wall C is 3.812 inches or substantially 95 millimeters, and since each endwall 30 is radially spaced from wall C by a total distance of one-quarter of an inch or about six millimeters, the radial distance of each end-wall 30 of the test mill from rotor-axis is substantially 3.6 inches or about 90 millimeters. Hence, in each complete revolution of the rotor, each end-wall 30 is moved through a distance of substantially 23 inches or about 0.565 meter. Hence, when the rotor of the test mill is rotated at 4,000 revolutions per minute, the outer tip or outer end-wall 30 of each rotor-blade or rotor-vane is moved in a circular path at a rate which is close to seventy-five hundred feet per minute or close to 2,260 meters per minute.

FIG. 4 shows that one wall of each casing of the apparatus shown in the drawings has a diametral inlet opening FA. The diameter of said opening FA may be substantially equal to or slightly greater than or slightly less than the total radial distance of 1.914 inches or about 47 millimeters between radially opposed apex edges 29 of the blades of the apparatus shown in the drawings. This diameter of said inlet opening FA may be substantially equal to the distance between of 1.329 inches between adjacent faces of the rotor blades. In the test mill, the diameter of said inlet opening PA is similarly dimensioned in proportion to said respective distances in the test mill, Thus the diameter of said inlet opening FA in the test mill may be substantially 1.5 inch or substantially 37.5 millimeters.

In the test mill, the single casing has a single rectangular top outlet, whose length in the direction of the rotoraxis 140, is three inches or about 75 millimeters, and whose width is seven-eighths of an inch or about 22 millimeters.

In said test mill, as above noted, the clearance between wall C and the inner flat faces of the vortex-creating bars is substantially 3,125 microns, and this is also the clearance between said inner fiat faces and the proximate tips 9 of the four rotor-blades 1515a, which are equally angularly spaced.

In some successful tests of the test mill, the initial particle size of the solid particles which were fed into the test mill exceeded 3,125 microns and even exceeded 4,000 microns. In other successful tests of the test mill, said initial particle size was less than 3,125 microns.

In the test mill, the axial dimension of the single casing, in the direction of axis 14c, was four inches or about 100 millimeters.

This is the axial dimension of each of the two casings I2 and 12a which are shown in the drawings.

As one preliminary example, the test mill was used to comminute or work zircon sand ore and also to com minute zirkite. Zircon ore is zircon silicate, ZrSiO.,. This first mentioned zircon ore is a natural zirconium silicate, which is described in page 1196 of the 1956 edition of The Condensed Chemical Dictionary published by Reinhold Publishing Corporation and Chapman 8: Hall, Ltd.

Zirkite is a name applied to baddeleyite that contains appreciable zircon oxide with silicon impurity. This is described in pages 123 and 1199 of said 1956 edition of said The Condensed Chemical Dictionary.

When the zircon sand ore was fed into the test mill, the original average particle size of zirkite sand was close to 149 microns. After being worked in the mill, about 62.3% by weight of said comminuted crude Zircon sand ore had a particle size smaller than 44 microns.

When said zirkite ore was fed into the test mill, the original particle size of said ore was up to nine thousand microns (about five-sixteenths to three-eighths of an inch) and the comminuted zirkite had the particle sizes later reported. In this case, the initial particle size of some of the zirkite ore was greater than the total clearance in the test mill between the tips of the blades and the inner wall of the casing.

These tests with the test mill showed substantial lack of abrasion at a constant rotor speed of 6,000 revolutions or more per minute in Working the zircon sand ore, and substantial lack of abrasion by the zirkite at the rotor speeds later mentioned.

These tests showed that the fine zircon sand ore and the relatively coarse zirkite were cernminuted before the com minuted particles emerged from the respective radial columns.

In addition to the tests on crude ores later reported herein, the test mill has been operated in other tests with negligible abrasion, if any, at suitable rotor speed to comrninute steel particles to powdered steel; to cornminute pieces of Wood to wood pulp; to comminute rags to a cottony fluff; and to comminute pieces of glass to a glass powder, and to comminute granite and also to homogenize milk and also to comminute grains.

In these tests, the starting material, including the milk, was mixed with air anterior the inlet ends of the rotating columns, namely in the inlet FA.

In all of these tests, air was drawn into the single inlet PA or the single casing of the test mill into the inlet ends of the columns, from an external atmosphere of air, which was at a pressure of substantially 760 millimeters of mercury, and at a temperature of substantially 20 C.40 C. The air was thus drawn in by the suction which was produced by the centrifugal action of the rotor-blades. The ore or other starting material, in unison with the air, was also fed into the single casing of the test mill through said single inlet FA after the speed of the rotor had been raised to the selected rotor speed, and after the desired condition had been secured in each column. The mixture of air and the comminuted or worked starting material was discharged from the single casing of the test mill into said external atmosphere, by said centrifugal action, through said single outlet of said single casing of the test mill. Said single casing was air-tight, save for its single inlet and its single discharge outlet.

Instead of working a mixture of starting material with air or other gas.

air in the improved mill, said air can be replaced by any gas or vapor or by any medium in which compressural waves can be generated and propagated. I

The invention is not limited to comminuting solid materials or to comminuting any other material, and it is not limited to working a starting material in admixture with Thus, the invention can be used for comminuting sand or other material which contains oil, in order to liberate the oil.

The invention can be used for mixing liquids and also for working a single liquid. In such case, the liquid or liquids can be worked, either with or without admixture with air or other gas or vapor. a

The invention can also be used for working emulsions or suspensions. Thus, the invention can be used, as for homogenizing milk, mixed or unmixed with air or other gas. The invention can be used, as one example, to work a suspension of kaolin particles in water, in order to re duce the size of said kaolin particles.

In the tests described herein, the test mill was at 20- 40 C. during the tests. The mill can be heated to have a higher working temperature, in order to liquefy solid starting materials, such as creams and ointments which are not liquid at 20 C.40 C. In said test mill, the single casing, the single rotor, and the fan blades of the single rotor, and the vortex-creating bars, which were made of unhardened steel, were readily abraded by solid particles which had a hardness above 6 in the wellknown Moh scale of hardness. As one reference in order to identify said Mo'n scale of hardness, said Moh scale of hardness is disclosed in page 5 8 of Langes Handbook of Chemistry, published in 1934 by Handbook Publishers, Inc. The respective hardness numbers of several materials in said Moh scale are stated below:

Prior to describing the improved mill in detail, a preliminary report is given of the test With said crude zirkite ore or baddeleyite ore in the test mill.

TESTS WITH CRUDE ZIRKITE ORE, WITH THE FIVE VORTEX-CREATING BARS OF THE SIN- GLE CASING IN POSITION This original crude zirkite or baddeleyite ore had colors ranging from pink to yellow. It had a hardness of 7.5 in the Mob scale. It was treated Without any preliminary concentration, save. to screen the crushed pieces from larger pieces.

In each test of the test mill reported herein with each of the crude ores later mentioned herein, with one exception later noted, a batch of five pounds or about 2.25 kilos of the respective crude ore intermixed with air, was fed into the single casing of the test mill through the single inlet FA, and such mixture 'was worked in the test mill in order to comminute the initial pieces or particles of the crude ore. In each test, with each crude ore, the test mill was operated in the same manner as under actual, continuous, working conditions.

The initial, coarse, average particle size of the crude zirkite ore which was fed into the test mill, and which was worked in the test mill while mixed with air, was one-eighth of an inch with variations in size up to threeeighths of an inch or about 9,300 microns and also with particle smaller than one-eighth of an inch.

The particle size of the solid comminuted zirkite ore and other comminuted ores which emerged from the test mill, was tested in every test which was made with every ore, by means of sieves which were numbered according to the U.S. Sieve Series, which is described in page 643 of Langeh Handbook of Chemistry.

Sieve number: Sieve opening 100 microns 149 200 rln 74 325 d 44 Hence, if a particle can pass through a No. 325 sieve, the size of said particle is calculated herein as being 44 microns or less.

If a particle can pass through a No. 200 sieve, but cannot pass through a No. 325 sieve, the size of said particle is calculated herein as being 74 microns or less, but more than 44 microns.

If a particle can pass through a No. 100 sieve, but cannot pass through a No. 200 sieve, the size of said particle is calculated herein as being 149 microns or less, but more than 74 microns.

If a particle cannot pass through a No. 100 sieve, its size is calculated herein as being more than 149 microns.

In a first test with said crude zirkite ore, the single rotor of the test mill was rotated in its single casing at substantially 4,000 revolutions per minute, specifically at 4,250 revolutions per minute. There was some slight abrasion of the blades, which was not substantial.

The results of the sieve analysis of the comminuted particles of crude zirkite ore, which consisted of a mixture of particles of zirconium oxide and particles of quartz, are stated in the following Table 1, in which the percentages are by weight.

Table No. 1

Percentage by weight: Particle size 6 More than 149 microns. Less than 149 microns, more than 74 microns. 21 Less than 74 microns, more than 44 microns.

58 Less than 44 microns.

Hence, only 6% by weight of the comminuted particles of the zirkite ore could not pass through a No. 100 sieve; 58% by weight of said comminuted particles could pass through a No. 325 sieve; and substantially 80% by weight of said comminuted particles could pass through a No. 200 sieve. These results applied to the valuable particles of zirconium oxide, ZrO and the valuless particles of quartz. All these comminuted particles were much smaller than the clearance of 3,125 microns between the outer tips of the rotor blades and the vortexcreating bars in the test mill. In a second test with zirkite ore, using the same startmg material and the same test conditions, save for a higher rotor speed of 8,500 revolutions per minute, better results were secured without any perceptible abrasion of the rotor-blades, because the generated air vortices and compressural waves had higher frequency and higher kinetic energy and the rotating columns of material in the spaces between the rotor blades had greater kinetic energy. The results of the sieve analysis of the comminuted particles of crude zirkite ore in the better second test, are stated in the following Table No. 2, in which the percentages are also by weight. These results also apply to the valuable particles of zirconium oxide and to the valueless particles of quartz, which were intermixed in the particles of the comminuted crude zirkite ore.

Table No. 2

Percentage by weight: Particle size 3 More than 149 microns.

6 Less than 149 microns, more than 74 microns. 19 Less than 74 microns, more than 44 microns. 72 Less than 44 microns.

Hence close to by weight of all the comminuted particles of zirkite ore could pass through a No. 325 sieve; and only 3% by weight of said comminuted particles could not pass through a No. sieve.

As a general average of all the tests of ores reported herein, when the five vortex-creating bars were in position in the single casing of the test mill, substantially 80% by weight of all the comminuted particles of the respective comminuted ores could pass through a No. 325 sieve, corresponding to a particle size of 44 microns or less, and all said comminuted particles were smaller than the clearance of 3,125 microns between the outer tips of the rotor blades and the vortex-creating bars. When the five vortex-creating bars were in position in the single casing of the test mill at the stations 1Zbl2c12d iZe-lZf, all the tests of all the ores and other materials mentioned herein, showed tiat abrasion of the test mill, it any, was negligible, especially at suitable high rotor speeds beginning with 7,000 revolutions per minute in the test mill.

When the five vortex-creating bars were removed from the single casing of the test mill, all other test conditions being the same, a general average of only substantially 69% by weight of all the comminuted ore particles of the tested ores could pass through a No. 325 sieve, and there was substantial abrasion of the test mill, and the comminuted particles did not have the same uniformity in size as when the vortex-creating bars were in position.

The ratio of air to solid starting material is easily determined by routine tests, since the period of feeding the solid ore material into the test mill is stated in each case and the volume of air which flows through the mill, due to its centrifugal suction action, is easily measured.

In working said crude zirkite ore, when the rotor was operated at 4,250 revolutions per minute, the five pounds of crude zircon ore were fed into the mill in substantially 52 seconds. When the rotor speed was 8,500 revolutions per minute, the feeding time of the five pounds of zirkite ore was substantially 29 seconds.

MICROSCOPIC EXAMINATION OF COMM- NUTED ZERKITE ORE This microscopic examination of said ore which was comminuted in the test mill as above stated, showed substantially clean and definite and desirable separation of all or substantially all of the valuable particles of zirconiurn oxide from the valueless particles of silica or quartz. The valuable, separated comminuted particles of zirconium oxide were thus produced in pure or substantially I pure form. This desirable result could be secured only in best results when the five vortex-creating bars were in position in the single casing of the test mill and the rotor speed was suitably high, as at 7,000 revolutions per minute or more. As above noted, when said five bars were in position in the single casing of the test mill and the rotor speed was suitably high, there was negligible abrasion, if any, of the test mill.

In the test mill, even at the lower rotor speed of 4,250 revolutions per minute, with the five bars in position in the test mill, there was a negligible production of valuable particles of zirconium oxide or other valuable ore particles which had the undesirable blunt and rounded edges. At the higher rotor speed of 8,500 revolutions per minute with the five vortex-creating bars in position in the test mill, there were no indications of blunt and rounded edges in the respective valuable particles, and there were no other indications of mechanical mill action.

Without limitation thereto, a two-unit embodiment of the invention is further disclosed in the annexed scale drawings and in the following description. The drawings and description herein embody the principle and the operation of the test mill.

FIG. 1 is a top plan view of the tw0-unit mill.

FIG. 2 is a front elevation of FIG. 1. FIGS. 1 and 2 13 are to the same scale, which is smaller than the scale of FIGS. 3 and 4.

FIG. 3 is a transverse, vertical section on the line 3-3 of FIG. 1.

FIG. 4 is a longitudinal vertical section, partially in elevation, on the line 4- of FIG. 3.

FIG. 5 is a section, partially in elevation, on the line 5-5 of FIG. 4. FIG. 5 is to a smaller scale than FIGS. 3 and 4.

FIG. 6 is a side elevation of a modified rotor, which is useful in working liquid or fiowable starting materials, which are worked either with or without admixture with air or other gas. FIG. 6 is to the same scale as FIG. 5.

FIG. 7 is an enlarged partial view of the mill shown in the drawings, to exact scale, in which the dimensions are marked in inches. Each dimension of FIG. 7 is tWo thirds of the respective actual dimension of the two-unit mill.

7 is in the same plane as FIG. 3.

The- casings 12 and 12a, the rotors 14 and 14a, the eight radial rotor-blades or rotor-vanes 15-15a, the ten bars R, and the ten recesses RA are respectively identical.

The parallel axes of rotation 140 of the rotors 14 and 14a are shown in horizontal position, but the invention is not limited to said horizontal position.

The two respective rotor-axes 140 are parallel. For convenience, the direction of these two rotor-axes 140 is designated as the longitudinal or axial direction.

Each longitudinal casing 12 and 12a has a part-cylindrical outer wall CA, which is concentric with the respective rotor-axis 140. Each said casing 12 and 12a has an inner wall C which is of part-cylindrical shape, save where the part-cylindrical recesses RA are located. Each inner wall C is concentric with the respective rotor-axis 140, save where the recesses RA are located in each inner wall C.

Each casing 12 and 12a thus has an outer leg or branch, which has a vertical, planar, longitudinal edge 46a. Each casing 12 and 12a also has a proximate leg or branch, which has a horizontal, planar, longitudinal edge 460.

Each casing 12 and 12a is open at its front and rear ends. These front and rear ends have proximate vertical, transverse, front and rear planar edge-parts 127. As shown in FIG. 4, these edge-parts 12 are annular and peripheral parts of the end- walls 7 and 7a. These edge-parts 12 have proximate and planar walls BA and SA which are perpendicular to axis 140.

The front ends of both casings 12 and 12a areclosed by the common transverse front wall 7, and the rear ends of said casings 12 and 12a are closed by the common transverse rear wall 7a. These walls 7 and 7a are identical. They have vertical edges intermediate the edgepart 12f. The edges B are parts of cylindrical flanges.

Each pair of said cylindrical flanges B is concentric with the respective rotor-axis 14c. These four cylindrical flanges B are substantially identical.

As shown in FIG. 4, the open front and rear ends of each horizontal and longitudinal recess RA are located at the cylindrical peripheral wall of each respective cylindrical flange B. Said recesses RA extend longitudinally and horizontally beyond the respective cylindrical flanges B, into the respective walls BA, to form recesses in said respective walls BA. The front and rear ends of each bar R extend into a respective pair of the recesses in the two respective front and rear walls BA. Said recesses may form bearings for the rods R, if said rods R are optionally turnable in their recesses RA. The front and rear ends of rods R may have tight drive fits in their recesses in walls BA, in order to prevent rods R from turning in their recesses M. If the vortex-creating rods R are turnable or non-turnable, they may be of cylindrical shape. The front or impinged faces RF operate to direct the vortices towards axis 140, and also in a circumferential direction reverse to the forward direction of the rotor.

1d The same etfect is secured in the test mill, in which the front faces of the vortex-creating rods R are flat and radial. Said front faces of rods R may be flat and inclined forwardly relative to each respective radius. As also shown in FIG. 4, the unrecessed parts of the front and rear ends of inner walls C of the casings 12 and 12a fit closely on the corresponding peripheral cylindrical parts of cylindrical flanges B.

The end- walls 7 and 7a have horizontal, cylindrical, longitudinal pins 10, in which the casing-walls CA fit closely, in the assembly of said casings 12 and 12a and their walls 7 and 7a.

The end- walls 7 and 7a are forced towards each other and they are clamped against the proximate walls of the front and rear edge-parts 12f ofveach of the two casings 12 and 12a, and also against the front and rear transverse, vertical and planar edges of the flat plates S and 13 which are later mentioned. FIG. 4 shows the front and rear vertical, transverse and planar edges SA of the plate S. The plate 13 which is shown in FIG. 3, also has such front and rear vertical, planar and transverse edges. Said plate 13 has a top face 46b anda bottom face 460.

As shown in FIG. 3, the lower flat plate 13 is fixed to the longitudinal, horizontal, planar edges of the adjacent inner legs of casings 12 and 12a, by means of screws 16a.

As also shown in FIG. 3, the upper plate S, which is also planar save at its opposed longitudinal edges which are shown in FIG. 3, is shaped to interfit with the outer legs of casings 12 and 1211. This upper plate S is fixed in position by screws 14b.

After the casings 12 and 12a have been thus assembled with walls 7 and 7a and with plates 13 and S, longitudinal and horizontal clamping bolts 8 are applied, in order to clamp the walls 7 and 7a to the front and rear transverse and vertical edge portions 12 of the casings 12 and 12a, and also to the corresponding front and rear planar edges SA of plate S, and also to the corresponding front and rear planar edges of plate 13.

Each bolt 8 has a rear head 9. The shank of each bolt 8 may be smooth and may fit closely in a pair of alined bores of walls 7 and 7a. In front of front wall 7, the shank of each bolt 3 is threaded, and a clamping nut 9a is applied, in order to clamp said assembled parts to each other.

Each said assembly is fixed to the base plate 6b by angular brackets 7b and screws 7c.

As shown in FIGS. 4 and 5, each rotor 14 and 14a has a disc-body D, which has a cylindrical periphery 14d.

This body D is sufficiently longitudinally spaced from inlet FA, so that the input solid or liquid materialdoes not strike body D. The disc-body D of each rotor 14 and 14a has a central cylindrical opening, whose wall has an internal thread. Each cylindrical and longitudinal rotor-shaft 5 and 5a has a reduced threaded end, which is screwed into the central opening of the discbody D of the respective rotor 14 or 14a. Said parallel shafts 5 and 5a are concentric with the respective rotoraxcs 14c, and the axes of said shafts 5' and 5a are in the same horizontal plane.

As also shown in FIG. 5, the base 15 of each rotor blade or vane has a longitudinal, cylindrical pin 45, which fits in a respective bore of the respective disc-body D, with a tight, drive fit, so that each vane or blade 15-15a is rigidly fixed to its rotor 14 or 14a and is rotated in unison with its rotor 14 or 14a around the respective rotor-axis 14c.

FIG. 3 shows one of the radial lines 46 of disc-body D. These radial lines 46 intersect at the respective rotoraxis 140.

As shown in FIG. 3, and also in FIG. 7, each vanebase 15 has a long, planar and longitudinal face 15f, which is parallel in the radial direction to a respective radial line 46, and each vane-base 15' also has. a short,

spasms l planar and longitudinal face d, which is parallel to the respective'long face 15 At its short face 15d, each vane-base 15 is recessed to provide a lug 17. Each outer vane-member 15a has a part which interfits with said recessed part of its vane-base 15. Each outer vane-member iSa has a planar and longitudinal face 15dd, which is continuous with the respective short face 15d of the respective vanebase 15.

Each outer vane member 15a is fixed to its base 15 by a screw 16.

Each outer vane-member 15a has an end-wall 3%, which is substantially longitudinally disposed and is sub stantially concentric with the inner wall C.

The base 15 of each rotor-blade 15-15:: has a planar I and longitudinally disposed end-wall 15g, which is perpendicular to the respective radial line 46.

Each outer blade member or vane member 15a, in addition to its end-wall 30, has a planar and longitudinally disposed wall '15e which is parallel to the respective radial line 46. Hence each assembled vane 15-l5a has an angular recess proximate to the respective inner wall C. Thus, the tips of the blades or vanes are of less width than the blade and this structure is provided by extending the forward vane portion radially outward to a greater extent than the rear vane portion. The extension of outer vane member 15a, beyond vane base 15, provides a superior vortex generation.

Each assembled vane or blade 15-15a has a uniform rectangular cross-section between its wall 15;; and its edge 15b. Said edge =15b defines a rectangular and planar face which is perpendicular to the respective radial line 46.

inwardly of said edge 15b, each assembled vane l.5l5a has two planar and longitudinally disposed faces 150, which are equally inclined to the respective radial line 46, and which meet in a common straight-line, horizontal and longitudinal apex edge 29.

Adjacent planar faces 150 of adjacent vanes 155u are parallel to each other.

As shown in FIG. 4, each entire blade or vane 15-15(1, from its outer end-wall 30* to its inner edge 29, extends longitudinally across substantially the entire axial length of each casing 12 and 12a, from the respective discbody D almost up to the front wall 7.

Each pair of adjacent vanes -15-15a, in combination with Walls 7 and 7a, thus forms a tapered column or space CC, which is located radially between the respective end-walls 3t and the respective edges or faces 1512. Each said tapered space or column CC has a relatively long wall l5dl5dd at one edge, and each said tapered space CC has a relatively short wall 15 at its other edge.

Proxirnate to the respective rotor-axis 140, the walls 150 of each pair of adjacent vanes 15-15a, and the walls 7 and 7a, forms a non-tapered column or space CD, which is of uniform rectangular cross-section. These columns CC and CD are rotated in unison around the respective rotor axis 140. The inlet ends of columns CD are at the apex edges 29 which are spaced from and are proximate to said rotor axis 140.

In this illustrated two-unit mill, the plates S and 13 form a common outlet or discharge channel 44 for both casings 12 and 12a. Since plate 13 has a top horizontal, planar and longitudinal face 46b, said outlet channel 44 has an inlet port 46a46b' at each end thereof. As

i3 shown in FIG. 3, the longitudinal faces of lower plate 13 are continuations of the respective walls C.

At its central part, the upper late S has a bore, to which a common outlet or discharge channels d is fixed by welding at a line WA. The comrninuted or worked starting material, or a mixture of air or other gas or vapor and the comminuted or worked starting material, enters the common outlet channel 44 in the respective opposed directions of arrows ll, and flows out of common outlet 4 in the direction of arrows i2 and 43.

In this embodiment and in the single casing of the test mill, the number of vortex-creating cars in the easing is unequal to the number of vanes i5-15a in the casing, but the invention is not limited to this feature. The number of bars in the casing may be equal to the number of vanes 15-l5a in the casing. However, tests have shown that it is highly preferable to have more vortax-creating oars than vanes 15-d5a in each casing, and also in the single casing of the test mill, and to have five such vortex-creating bars in relation to four equally spaced blades or vanes 15-15a and to locate said five vortex-creating cars in the test mill as shown as in the drawings.

In each casing, and also in the single casing of the test mill, the positions of the five bars R are indicated by The angles between these stations are the angles along respective radial lines 46, and the parallel, horizontal and longitudinal axes of the cylindrical or non-cylindrical vortex-creating bars.

in this highly preferred embodiment and also in the single casing of the test mill, but without limitation thereto, these angles are as follows:

12b to ninety degrees. 120 to 12d: sixty degrees. 12d to 12s: sixty degrees. Me to 12 f: sixty degrees. 12f to 32b: ninety degrees.

For convenience, the station 12!) is designated asthe front or outlet station, and the bar at station 12!) is designated as the front bar. Similarly, the bar at station 12c is conveniently designated as the rear bar, the bar at station 12 is conveniently designated as the next-preceding bar, and the bars at stations 12d and 12e are conveniently designated as the intermediate bars.

in general, there is a greater angle between the front bar and the respective outlet port ida-46b, than between said outlet part 46a46b and the rear bar; and there is a greater angle between the front bar and the next-preceeding bar than the angles of the intermediate bars relative to the next-preceding bar and the rear bar. These general rules apply to fixed bars and to rotatable bars, and to a mill which has a single unit, such as the test mill.

The number of bars and the number of vanes 15-15a may be varied.

If there are four vanes 15-15a, and four bars, one of said bars may be located at station 1212, another bar is located at station 120, and there are equal angular spacings between these two bars and the other two bars.

The purpose of locating five bars R relative to four vanes 15-450 is to provide, in some parts of each casing, a single front impinged face RF for each partial vein of air or material which is emitted from a respective rotating tapered column CC and which is flowed in the respective forward circumferential direction; and to provide, in other cases, at least two front impinged faces RF for each said partial vein of air.

In this two-unit mill, there is a single inlet hopper 3, which has two bottom openings, which are respectively connected to respective feed pipes 3a and 3b. The mixture of air and starting material, or the starting material unmixed with air, enters hopper 3 in the direction of arrows 40.

The front wall 7 has acylindrical inlet bore for each 17 casing, which is concentric with the-respective rotor-axis 14c.

A bushing F has a cylindrical sleeve which has a hollow cylindrical inlet FA, which is concentric with the respective rotor-axis 14c. The diameter of said inlet FA may be equal to or less or slightly greater than the diametral distance between radially opposed apex edges 29. The material is flowed through inlet FA so as to enter the common inlet Zone or space between the apex edges 29.

Each bus-hing F has a planar flange which is in front of front wall 7, and said flange is fixed to front wall 7 by screws 20.

The lower end of each feed pipe 3a and 3b is welded to the respective bushing F at a weld line W.

Usually, if a solid material is to be worked, said solid material is equally fed into each respective inlet FA wholly or partially by gravity, while air or other gas or -a vapor is drawn equally into each inlet FA by the suction effect of the mill. Hence, during operation, each inlet FA may be kept wholly or partially filled with the input particles or pieces of solid material. If the input particles of solid material are light and small, they may be drawn into each inlet FA by the current of air which is drawn into each inlet FA. At high rotorspeeds, such as a rotor speed of the test mill which begins at substa tially 7,000 revolutions per minute of the relatively small rotor of said test mill, there is substantial feed of starting material into the mill by the current of air which is produced by the mill.

The starting material may be injected into each casing of the mill through the respective inlet FA, with little'or no intermixed air or other gas. The starting material may be sprayed into the mill through the inlets FA, intermixed with air or other gas. feed of a mixture of starting material and air to each unit.

The respective cylindrical rotor-shafts and 5a are identical. They have respective fly- wheels 26 and 26a. FIG. 4 shows a conventional longitudinal key-slot K which is provided in each shaft 5 'and 5a, by means of which each shaft 5 and 5a can be driven from any source of power. In operation, these shafts 5 and 5a are rotated at equal and constant speeds, in the respective opposed forward directions 39 and 39a.

FIG. 4 shows identical, vertical and transverse walls 24 and 25, which are fixed toba-se-plate 612 by brackets 7d and screw 7c.

The tops of said walls 24 and 25have horizontal and longitudinal-1y alined pairs of half-cylindrical recesses.

The shafts 5 and 5a have identical, cylindrical bearings 6 and 6a. Each bearing 6 and 6a has its lower half fitting in a pair of recesses at the tops of walls 24 and 25. Metal straps 36 and 36a clamp these bearings 6 and 6a to the top faces of walls 24 and 25, by means of screws 33 and 38a which fix the lugs 37 and 37a of said straps to the top faces of walls 24 and 25.

As shown in FIG. 4, the disc-body D of each rotor 14 and 14a is located within a respective cylindrical bore of rear wall 7a, with enough clearance for easy rotation. A conventional air-tight packing is provided at each discbody D. Each shaft 5 and 5a fits closely and turnably and air-tight in a respective bore of a respective packingring 23, which is of the usual compressible and resilient type. Each packing ring 23 is at the front of a flat, rigid plate FAA, and a part of each packing ring 23 fits in a recess of a rigid plate 21. These plates FAA and 21 have bores through which the respective shaft 5 or 5a extends, with suitable clearance.

Clamping screws 22 fix plates FAA and 21 to each other and to wall 7a. Said screws 22 exert sufficient pressure to clamp each ring 23 between the respective plates FAA and 21, in order to compress the respective ring 23 in the usual manner.

Each casing 12 and 12a and thus air-tight, save at its single inlet FA and its single outlet 46a46b.

There is preferably equal .which is also designated as 14c.

18 The preferred minimum speed of each rotorshown' in the drawings is 8,000 revolutions per minute.

FIG. 6

This is to the same scale as FIG. 5. The disc-body 27 is the same as disc-body D. One of the radial lines 47 of disc-body 27 is shown. This disc-body 27 has an axis The front direction of rotation is indicated by arrow 27a. This embodiment has curved vanes 2-8, whose front faces are convex in the direction of rotation 27a. The vanes or blades 28 have said faces 15c, which meet in apex edges marked 48, which correspond to edges 29. This embodiment is suitable in circumferentially propelling liquid, or a mixture of liquid and air, in said tapered columns CC and in said uniform and non-tapered columns CD.

Other tests which were made with said test mill are reported below. In the next reported test, only air was fed through the test mill, in order to determine the external sound which resulted from the operation of the rotor of the test mill at different rotor speeds. The circumferential velocity of the tips of the rotor-vanes of the test mill, at each respective rotor speed, can be easily calculated from the preceding calculation.

TESTS OF THE TEST MILL, WHEN ONLY AIR IS FED TI-IERETO The rotor of the test mill was rotated at the following respective speeds, in revolutions per minute, while the five vortex-creating bars were in position.

At rotor, speeds between 4,000 revolutions per minute and 6,000 revolutions per minute, the test mill produced a very loud external mechanical noise, thus evidencing a large percentage of air-waves in the audible range, with a frequency of said large percentage of air waves at or below 9,000 cycles per second and with some air waves with a frequency at or above 20,000 cycles per second.

At rotor speeds above 6,000 revolutions per minute, the test mill produced a loud whirring noise, which decreased as the rotor speed increased. This evidenced that the percentage of air-waves in the audible range decreased as the rotor speed increased, with a larger percentage of airwaves of a frequency above the ordinary audible range of 9,000 cycles and even above 20,000 cycles per second. These high-frequency air waves were generated by the vortices which were generated at the vortex-creating bars.

At the maximum test speed of 14,000 revolutions per minute of the rotor, the test mill produced only a loud external hum, which evidenced that the major proportion of the air waves had a frequency above 9,000 cycles per second and even above 20,000 cycles per second. This resulted from the greater frequency and kinetic energy of the vortices.

In the following reported tests and as above noted, each test was made by feeding five pounds of the respective solid ore material, mixed with air, through the test mill, save that in one case the input batch was ten pounds of solid ore. In each case, the time of feeding each batch of ore into the test mill, is stated in seconds. The time of feed of each batch of ore into the mill depended substantially upon the speed of rotation of the rotor, the initial coarse particle size of the orew hich was fed into the test mill, and the ratio of water in the initial coarse particles of ore which were fed into the mill, and also depended upon the respective ore.

TEST MADE IN TEST MILL WITH CRUDE COPPER ORE. FIVE BARS IN POSITIONv in each test, a mixture of the crushed crude copper ore 19 and air was fed into the test mill. The copper ore was not subjected to any preliminary treatment, save crushing and the screening to separate the crushed particles.

In addition to impurities, this crude copper ore, which had little or no metallic copper, had the following valuable copper compounds:

Malachite.This is generally described as green carbonate of copper. It is a native hydrated basic carbonate. Its formula is Cu (OH) CO or CuCO .Cu(OI-I) or 2 CuO.CO .H O. It is described in page 677 of said 1956 edition of The Condensed Chemical Dictionary. Its hardness in the Moh scale is 3.5 to 4. It contains by weight about 72% of cupric oxide (CuO) and about 20% of carbon dioxide, the balance being water.

Chalccite.This is a natural cuprous sulfide, Cu S. Its hardness is 2.5 to 3 in the Moh scale. It is described in page 251 of said 1956 edition of The Condensed Chemical Dictionary.

Cuprite.-This is cuprous oxide, C11 0. I-ts hardness in the Moh scale is 3.5 to 4.

This crude copper ore had a large proportion of impurity. It assayed only about 3% by weight of metallic or elemental copper as a component of said copper compounds. Due to said large proportion of impurity, the hardness of the crude copper ore was substantially 6.0 to 7.0 in the Moh scale. This crude copper ore was sulficiently hard and abrasive to scratch the unhardened steel of the casing and rotor and rotor-blades of the test mill, if said copper ore were comminuted by the old mechanical mill action. The original color of this crude copper ore was greenish.

Five pounds of said crude copper ore, mixed with air, were fed into and passed through the test mill in each test. As above noted, and as in every other test reported herein, the air was drawn into the test mill from an external atmosphere having a pressure of substantially 760 millimeters of mercury, and a normal temperature of substantially 20 C. to 40 C., and the mixture of comrninuted material and air was discharged into said atmosphere. This crude input copper ore had an initial average coarse particle side of five-sixteenths of an inch, or about 7,800 microns, with particles above and below said size.

Although the crude input copper ore could abrade the inner wall of the casing and the rotor and its blades and the bars by mechanical mill action, there was negligible evidence, if any, of abrasion, especially at rotor speeds of the test mill beginning at about 7,000 revolutions per minute. At lower speeds, there was some slight abrasion which was substantially limited to the rotor-blades.

In the three respective batch tests, the respective rotor speeds, and the respective time of feeding the mixture of five pounds of said ore, mixed with air, into and through the test mill, were as follows:

Feeding time Rotor speed in revolutions per minute: in seconds Hence, an increase in order speed decreased the feeding time.

The color of the comminuted, crude copper ore ranged from a light copper grey at low rotor speeds to a dark copper grey at high rotor speeds, showing an increase in dark color with increasing rotor speed.

As previously noted, the average particle size, in the respective cornminuted ores tested herein, showed that about 80% by weight could pass through a No. 325 screen. This small particle size evidenced comminution by air waves and vertexes.

This change of color again showed the effects of sonic air waves whose frequency was abo e the ordinary audible limit which begins at substantially 9,000 cycles per secend to substantially 10,000 cycles per second.

Microscopic examination of the crude comminuted copper ore, especially at a minimum rotor speed of substantially 7,000 revolutions per minutes, showed that the valuable comminuted particles of copper compounds had sharp, clean edges and were cleanly separated from the valueless particles. Hence said crude, comrninuted copper ore could be readily treated by the flotation process or other process, in order to separate the valuable particles of said three compounds of copper, from the valueless particles of impurities.

TESTS MADE OF TEST MILL WITH CRUDE TUNGSTEN ORE. FIVE VORTEX-CREATING BARS IN POSITION In addition to impurities, this original crude tungsten ore was a combination or complex of the following valuable ingredients or metallic compounds:

Scheelite.-This is CaWO It is a natural calcium tungstate. It is described in page 969 of said 1956 edition of The Condensed Chemical Dictionary. Its hardness in the Moh scale is 4.5 to 5.

Wolframite and ferberite.-Wolframite is a natural tungstate of iron and manganese. Ferberite is the ironrich member of this class. Both wolfrarnite and ferberite are described in page 1173 of said 1956 edition of The Condensed Chemical Dictionary.

This ore was not treated prior to comminution, save possibly for prior crushing and screening.

Due to the large amount of quartz impurity, this crude input tungsten ore had a hardness of 7.0 to 7.5 in the Mob scale. This ore had only about 2% by weight of metallic tungsten as a component of said compounds. The initial average coarse particle size of this ore, was six thousand microns, with larger and smaller particles. Five pounds of said crude tungsten ore, mixed with air, were passed through the test mill in each test. The respective rotor speeds and feeding times into and through the test mill were as follows:

Feeding time Rotor speed in revolutions per minute: in seconds The mixture of tungsten ore and air passed through the test mill in less time than the mixture of the previously-mentioned copper ore with the air. One reason was the smaller, initial particle size of the tungsten ore. Also, the crushed copper ore was damp, and had about 5% by weight of water.

A microscopic analysis showed the abovementioned good separation results, especially at a rotor speed of substantially 7,000 revolutions per minute or more. The original color of this tungsten ore was brown. The color of the comminuted tungsten ore was grey.

The pure particles of valuable tungsten compounds were separated from the valueless particles. The valuable particles had sharp edges, especially at a minimum rotor speed of 7,000 revolutions per minute.

TESTS IN TEST MILL ON CRUDE PLATINUM ORE. FIVE VORTEX-CREATING BARS IN POSI- TION This crude ore was not subjected to any preliminary treatment, save for crushing and screening.

This crude platinum ore Was an ore found in California and Nevada. It contained native or metallic platinum. This crude ore was crushed to an initial average coarse particle size of one-fourth of an inch, or about 6,000

241 old method of recovery of platinum is to wash the native ore in running water, in order to remove a large part of the sand and other impurities, and to produce a concentrate.

The particles of native platinum which are in the concentrate of the ore which is produced by the old method, are so small and of such low concentration, that such particles of native platinum must be recovered in the old ethod by an expensive chemical process to produce platinum sponge, which must be heated in an electric furnace. This results in a large loss of platinum.

In these tests with the crude platinum ore, three successive tests runs were first made, each with a batch of five pounds of said crude, crushed platinum ore, mixed with air.

Feeding time Rotor speed in revolutions per minute: in seconds The clarkeningin color of this original grey, crushed I platinum ore to a darker grey color was more noticeable than in Working or comminuting said zirconium, copper and tungsten ores.

As a further test, ten pounds of the same crushed platinum ore were fed through the test mill, mixed with air, while the rotor was rotated at 14,000 revolutions per minute. The resultant comminuted ore had a blackish-grey color, which was much darker than at lower rotor speeds, thus showing the effect of air vortices and air waves of increased frequency and increased kinetic energy.

Some of the comminuted platinum ore was panned, in order to secure a concetrate of said platinum ore. As a novel and pioneer result, this panned concentrate had a fair proportion of particles of native platinum which could be easily picked by hand from the concentrate. This has hitherto been considered impossible in the mining industries, because of the very small original particle size of the native platinum in the original ore. This test showed that these original, very small particles of native platinum were aggregated or coalesced by the working in the test mill. Hence, in many cases, it is mererly necessary only to crush and screen the crude ore in order to separate pieces or particles of suitable initial size, and to work the screened material directly in the improved mill and then to concentrate the comminuted ore, which can be very easily concentrated.

The improved method and apparatus are therefore suitable for recovering other native metals, as exemplified by gold, copper, silver and other metals which occur in the uncombined elemental state.

The original crushed platinum ore assayed at only $64.00 per ton. By the method and apparatus of this invention, the concentrate of the comminuted ore had an assay of substantially $2,000.00 per ton when said concentrate was secured by ordinary panning with water. This was due to the clean separation of the aggregated particles of platinum from the impurities.

In all these tests with the vortex-creating bars in position in the test mill, it was proved that it was possible to get a much higher rate of recovery from the comminuted ore by the flotation process than has ever been accomplished in the mining industry. It is possible to recover native metals from the comminuted ore by flotation, so as to increase present rates of recovery by as much as 100% to 200%. This is because of clean, welldefined separation of the valuable ingredients from the impurities.

TEST MADE WITH SAID COPPER ORE, WITH FIVE BARS REMOVED The initial average particlesize of the infed ore was also five-sixteenths of an inch, and all conditions were V 22 the same as in the previous test, save for the removal of the five vortex-creating bars. Five pounds of said ore were also fed through the mill in each test. The respective rotor speeds and feeding times through the mill were as follows:

Feeding time Rotor speed in revolutions per minute: in seconds Each five-pound batch was fed muchmore-quickly than in the prior test in which the five vortex-creating bars were in position, because the mill took in the copper ore much more quickly. The mechanical mill effect with abrasion of the mill, was the dominant efiect. Also, when the bars were out, the feeding time and the performance of the test mill was very irregular and unpredictable, in that the particles or comminuted ore diifered greatly in size, when successive batches were worked. When the bars are in position, the test mill gives uniform and predictable performance in producing comminuted ore of substantially uniform particle size.

TESTS MADE WITH SAID PLATINUM ORE, WITH FIVE BARS REMOVED Feeding time Rotor speed in revolutions per minute: in seconds As previously noted, the change in feeding periods was not uniform in relation to change in rotor speed. The main effect was mechanical abrasion or grinding.

' As previously noted in all the tests when the bars R were removed, an average of only 69% of the respective comminuted particles could pass through a No. sieve, and about 5% by weight could not pass through a No. 100 sieve.

In each rotating air column there will be a combined effect of the kinetic energy of the vortices, the kinetic energy of the generated air waves, and the rotational kinetic energy of the air.

The non-tapered columns CD will concentrate this combined kinetic energy, whose eifect is transmitted into the common space between the apex edges 29. At suitable rotor speed, there will be a sufiicient ratio of generated air waves of superaudible frequency and high kinetic energy.

The generated vortices which travel towards the rotor axis retard the outward fiow of air in each rotating column towards its outlet end.

If a liquid is worked, such as milk, this liquid may be worked as a continuous mass Within the casing in the form of said rotating columns, or in the form of drops which are mixed withair, in the form of said rotating columns.

If the milk is worked as a continuous mass within casing 12 in said rotating columns, the vortices and the longitudinal, compressional waves are generated Within the rotating columns of said continuous mass of milk, so that the droplets of fat are decreased in size, in order to produce a homogenized milk.

If liquids are to be mixed, the liquids are fed in suitable ratio into the common space between the edges 29, to be mixed in said rotating columns. One of these liquids may have a dissolved surface-active or emulsify- 23 ing agent, so that the worked liquid which is discharged from the outlet port will be an emulsion.

If a suspension is to be worked, such as an aqueous slurry of uncalcined or calcined kaolin, the vortices and waves in the liquid medium in said rotating columns will reduce the particle size of t e suspended particles of kaolin. In uncalcined crude kaolin, it is well known to make an aqueous, deflocculated slurry of the uncalcined crude kaolin, and to separate the sand, mica and other coarse, abrasive impurities from said slurry, by means of sedimentation. The improved method and apparatus make it possible'quickly to separate the coarse impurities from the fine, deflocculated particles ofpurified kaolin, which will remain in deflocculated form in the slurry.

After said preliminary purification of crude uncalcined kaolin, it is well known to keep the purified deflocculated slurry of the uncalcined kaolin in a settling or sedimentation tank for a long period, in order to sediment the larger particles of uncalcined purified kaolin, while keeping the smaller particles of uncalcined purified kaolin suspended in the slurry, thus separating a fraction of pure uncalcined kaolin of small particle size from the larger particles of uncalcined kaolin. This desirable small fraction of uncalcined kaolin fine particle size is often used as a coating clay, for coating paper. This method makes it possible to comminute the particles of uncalcined purified kaolin directly in the rotating columns of sm'd purified slurry, thus producing a much larger yield of uncalcined kaolin particles of small size.

In making a coating composition for coating paper, it is the practice to make an aqueous solution or dispersion of the adhesive in one batch, to make an aqueous dispersion of the coating pigments in another batch, and then to mix these batches. The improved method and apparatus make it possible to produce an intimate mixture of these batches quickly and cheaply in said rotating columns, even if the dispersion of the coating pigments has high viscosity.

It is clear that the invention has many additional uses.

All the worked materials disclosed herein are or include materials in which vortices and compressural waves can be generated and transmitted. If the material is a mixture of a fluid and solid material, such vortices and compressural waves are generated in the liquid or gas or vapor, and said compressural waves are transmitted through the solid material.

Some of the important features of the invention, without limitation to said illustrative embodiments or their details, are stated below.

(A) Finishing the desired working in a column which is closed save for an inlet end and an outlet end, before the worked material emerges from the outlet end of said column.

Thus, if an ore is worked, this may optionally be reduced to the desired particle size, before emerging from the outlet end of the column, even the column which is in registration with the outlet opening. This may be done by means of vortices of suflicient kinetic energy.

(B) Maintaining a protective layer of fluid under sufficient pressure of suflicient depth at each section of the confining surface C, to prevent solid particles from abrading said sections and to prevent fluid material from abrading said sections. This layer of fluid may be stationary or it may be stationary relative to a flowing surface layer of material which flows over the respective impinged face of the vortex-generating element, which is illustrated by the bars R. Such protective layer is maintained at each said impinged face, and the flowing layer therefore does not abrade the impinged face and flows over said impinged face.

' (C) Using columns which have zones of less crosssection adjacent their inlet ends than the zones at their outer ends.

(D) Using columns which have at least three zones,

24 namely the zones CD of minimum cross-section; the tapered zones CC; and a final outer end-zone, as beyond the walls 15g.

(E) Securing the desired degree of Working by the combined kinetic energy of the columns and of the vortices and air-waves.

(F) Using such combined kinetic energy which is sufiiciently great to protect the blades against abrasion, although the invention is not limited to protecting the blades against abrasion.

(G) Producing solid particles which have sharp and clean edges, especially particles which have a definite crystalline structure. Also, the method and machine may utilize the rubbing of the work-pieces upon each other.

In the method, the desired effects require proper coordination between the outward velocity of outward flow of the material in each column; the clearance between the outer ends of the blades and the sections of the confining surface C; and the clearance between the outer ends of the blades and the vortex-generating members, and the forward velocity of the columns in a direction transverse tothe direction of flow through the columns. The forward movement of the columns may or may not be in an arcuate path, because. the invention is not limited to a mill or comminuting apparatus of the rotor type shown herein.

If the outward flow velocity is too low, or if the clearances at the outer ends of the columns are too great, or if both said factors are improperly selected, the protective layers are not formed at the face or wall C, and are also not formed at the front impinged faces of the vortexcreating members.

The clearance between the outlet ends of the columns and the confining surface C and the clearance between said outlet ends of the columns and the vortex-generating members must be selected, in proper relation to the forward velocity of the column, to provide vortices of surficient frequency and kinetic energy.

As above noted, these vortices should generate and maintain compressural Waves of high frequency, and provide and maintain suflicient turbulence in each column for the desired working.

Another feature of the invention is to transmit the effect or energy of the vortices and compressural waves from the outer ends of the columns to their inner ends, and even optionally into the entire space between said inner ends, while preventing any excessive escape of said effect or energy from said space, but using an inlet opening of suitable small dimension which opens into said space. While it is preferred to provide a confining surface C of cylindrical shape, the invention is not limited thereto.

The invention is further disclosed both in subject matter and scope in the appended claims. It includes an improved cornminuted ore, in which the metalliferous particles, either compounds or native metal, have sharp and clean edges. It also includes a method in which the original crude or impure ore, save for any necessary preliminary crushing and screening to separate particles of a suitable input size, is worked in substantially its original composition or namely, with substantially all of its original ingredients, thus optionally eliminating any substantial prior concentration of the original ingredients, thus eliminating any substantial prior concentration of the original crude or impure ore.

I claim:

1. A method of working a mixture of a fluid and pieces of solid material which are comminuted by said working, said fluid being of the class in which vortices and compressural waves can be generated and transmitted, which consists in working said mixture in a column which has a material inlet end and a material discharge end while feeding said mixture in a forward direction from said material inlet end toward said material discharge end, said column having an enclosing wall between said inlet end 25 and said outlet end said wall being lateral relative to said forward direction, feeding said mixture into said inlet end and feeding said mixture through said column in said forward direction to emerge from said outlet end in the form of an outlet discharge mass of said mixture, simultaneously moving said coiumn in a forward rotary direction of column movement which is transverse to said outlet feeding direciton, said' forward rotary direction being about an axis adjacent said material inlet end, thus providing said outlet mass within said column with a movement which has an outward component in said outlet feeding direction and a forward component in said forward rotary direction, directing said outlet discharge mass against a confining surface which limits the movements of said outlet discharge mass in the direction of said outward component, maintaining an outer protective layer of said fluid of said outlet mass at said confining surface to substantially protectsaid confining surface from abrasion by the solid material which emerges from said outlet end, moving an inner surface layer of mixed fluid and the solid material which emerges from said outlet end in said forward direction of rotary movement to impinge upon a stationary vortex-generating member while passing the solid material of said inner and forwardly moving surface layer over said stationary vortexgenerating member to substantially prevent abrasion of said stationary vortex-generating member by the forwardly moving solid material of said forwarly moving inner surface layer, While generating a series of vortices in said forwardly moving fluid of said surface layer at said stationary vortex-generating member while said outlet end passes across said vortex-generating member, transmitting said vortices into said column through its outlet end and also within said column in a transmitted direction which is opposed to said, outlet feeding direction, and comminuting said pieces of solid material substantially within said column by the kinetic energy of said vortices.

2. A method according to claim 1 in which said solid material is a crude ore which has a metalliferous part and gangue impurities, and said vortices have sufiicient energy to comminute said crude ore, and by said comminution there is providedcomminuted particles of the metalliferous part of said ore which have sharp and clean edges and which are separate from the comminuted gangue impurities of said ore.

3. A method according to claim 2 in which the metalliferous part of said crude ore is a compound of a metal.

4. A method according to claim 2, in which said metalliferous part includes a native metal.

5. A method according to claim 4, in which the crude ore contains native platinum.

6. A method according to claim 2, in which the crude ore is worked in substantially its original composition and the comminuted metalliferous particles are separated from the particles of gangue impurities after said workmg.

7. A method of working a material to a final desired form, said material being of the class in which vortices and compressural waves can be generated and transmitted, which consists in working said material in a column which has a material inlet end and a material discharge end and which is located in a fixed chamber which has a fixed confining surface and which is closed save at a dischange opening, said column having material-confining walls between said inlet opening and said material discharge outlet opening save at said outlet opening, said material being flowed through said column in a forward direction from said material inlet end to said material discharge end, two of said material-confining walls being stationary walls of said chamber, said column also having front and rear material-confining walls which are movable relative to said stationary walls, which consists in simultaneously rotating said front and rear material-confining walls in fixed angular relation in a forward circular direction relative to said stationary walls around an axis adjacent to said inlet end to create outward centrifugal force in said column, feeding the material into said material inlet end, feeding the material as an outlet discharge mass by said centrifugal force out of said material discharge end in the direction towards said confining surface while also moving said discharged outlet mass relative to said confining surface in said forward circular direction, creating enough centrifugal force to form a compressed protective layer of said material at said confining surface to prevent direct contact impact of said outlet discharge mass against said confining surface, impinging the forwardly moving part of said outlet discharge mass against a plurality of stationary vortex-generating members which are fixed to said confining surface and extend inwardly from said confining surface and which are located anterior said discharge opening while flowing said forwardly moving part over said stationary vortex-generating members to substantially prevent direct contact between said forwardly moving part and said vortex-generating members, generating vortices at said vortex-generating members, and transmitting said vortices into said column in a direction towards the inlet end of said column.

8. A method according to claim 7 in which there is an anterior vortex-generating member directly anterior said discharge opening, and some of the vortex-generating members are in a zone in which their spacing is less than the spacing between said anterior vortex-generating member and said discharge opening.

9. A method of comminuting pieces of solid material, which consists in feeding a mixture of said solid material and a fluid in a selected feed direction through a column between the inlet end of said column and the outlet end of said column, generating vortices of a fluid in a zone which is proximate to said outlet end, transmitting said vortices within said column in a direction opposed to said feed direction, generating compressural waves in said material and fluid within said column by said vortices, enough kinetic energy being generated in said compressural Waves within said column by said vortices to reduce said material within said column by said compressural waves, said column being closed between its inlet end and its outlet end. V

10 A method according to claim 9 in which said column has a column axis between its inlet end and its outlet end, said column axis is transverse to an axis of rotation which is proximate to and spaced from said inlet end in a direction opposed to said feed direction, the column is rotated in a forward direction around said axis of rotation to generate centrifugal force within said column to feed the said mixture radially through said column and out of said column in an outlet stream which has an outlet direction which has a forward component and an outward radial component, obstructing the flow of said outlet stream in the direction. of said radial component, and partially obstructing the flow of said outlet stream in the direction of said forward component to generate said vortices.

11. A method according to claim 10 in which said column has an inner zone at its inlet end and an outlet zone at its outlet end, said zones communicating with each other at their adjacent ends, said inner zone being of equal cross-section from its inlet end to said communicating ends, said outer zone increasing uniformly in crosssection from said communicating ends to said outlet end.

12. A method according to claim 10 in which the solid material is a crude ore and the fluid is an aeriform fluid, and said crude ore is commiuuted into metalliferous particles of said crude ore having sharp and clean edges, and into particles of the gangue of said crude ore.

13. A method according to claim 9 in which the solid material is a crude ore and the fluid is an aeriform fluid, and said crude ore is comminuted into metalliferous particles of'said crude ore having sharp and clean edges and into particles of the gangue of said crude ore.

14. A mill which has a casing which has a substantially cylindrical inner peripheral wall, said casing having a front casing wall and a rear casing wall, said cylindrical inner peripheral wall having a horizontal axis, a casing wall of said casing having a horizontal inlet opening at said axis, said casing also having an outlet opening in said cylindrical inner peripheral wall, vortex-generating members fixed to said cylindrical inner peripheral wall and projecting inwardly from said cylindrical peripheral inner wall, a rotor turnable about said axis, angularly spaced rotor vanes fixed to said rotor and fitting substantially between said front casing wall and said rear casing wall, the outer ends of said vanes being spaced inwardly from the inner faces of said vortex-generating members, the clearance between said cylindrical inner peripheral wall and the inner faces of said vortex-generating members being substantially equal to the clearance between said outer ends and said inner faces of the vortex-generating members, said vanes extending radially inwardly from said outer ends thereof to provide between adjacent vanes radially extending columns defined by opposed faces of adjacent vanes, the opposed faces of adjacent vanes converging toward the rotor axis and terminating adjacent the rotor axis in mutually parallel face portions, each column having an inlet end proximate to the rotor axis and an outlet end proximate said inner peripheral wall of the casing, whereby upon introduction of a mix ture of solid material and a fluid in the said horizontal inlet of the casing and rotating of the vanes, vortices of the fluid can be generated in a zone proximate to the said column outlet ends and transmitted radially inwardly to generate compressional waves and reduce the material within the column.

15. A mill which has a casing which has a substantially cylindrical inner peripheral wall, said casing having a front casing-wall and a rear casing-wall, said cylindrical inner peripheral wall having a horizontal axis, a casingwall of said casing having a horizontal inlet opening at said axis, said casing having an outlet opening in said cylindrical inner peripheral wall, vortex-generating members fixed to said cylindrical inner peripheral wall and projecting inwardly from said cylindrical inner peripheral wall, a rotor turnable about said axis, angularly spaced rotor vanes fixed to said rotor and fitting substantially between said front casing wall and'said rear casing wall, the outer ends of said vanes being spaced inwardly from the inner faces of said vortex-generating members by a clearance which is less than the clearance between said cylindrical inner peripheral wall and the inner faces of said vortex-generating members, said vanes extending radially inwardly from said outer ends thereof to provide between adjacent vanes radially extending columns defined by opposed faces of adjacent vanes, the opposed faces of adjacent vanes converging toward the rotor axis and terminating adjacent the rotor axis in mutually parallel face portions, each column having an inlet end proximate to the rotor axis and an outlet end proximate said inner peripheral wall of the casing, whereby upon introduction of a mixture of solid material and a fluid in the said horizontal inlet of the casing and rotating of the vanes, vortices of the fluid can be generated in a zone proximate to the said column outlet ends and transmitted radially inwardly to generate compressional waves and reduce the material within the column.

16. A mill which has a casing which has a substantially cylindrical inner peripheral wall which has a horizontal axis and a front vertical casing-wall and a rear vertical casing wall, said front and rear'casing walls being perpendicular to said axis, said front casing wall having an inlet at said axis, said casing having a discharge opening above said inlet, a rotor which is rotatable around said axis, angularly spaced rotor vanes fixed to said rotor and extending substantially between said front casing-wall and said rear casing-wall, vortex-generating members fixed to said cylindrical inner peripheral wall and extending inwardly therefrom, the outer tips of said blades being spaced inwardly from the inner faces of said vortexgenerating members, the clearance between said cylindrical inner peripheral wall and the inner faces of said vortexgenerating members being substantially equal to the clearanee between said tips and said inner faces of the vortexgenerating members, said vanes having inner ends which are proximate to and spaced radially from said axis, adjacent vanes having adjacent parallel and substantially planar faces at their inner ends, said adjacent vanes having diverging fees from the outer ends of said planar faces.

17. A mill according to claim 16, in which the outer ends of said vanes have tips of less width than said vanes, the forward vane portion extending radially outwardly to a greater extent than the rear vane portion to provide said tips.

References (liter! in the file of this patent UNITED STATES PATENTS 1,175,782 Lovett Mar. 14, 1916 1,703,634 Podszus Feb. 26, 1929 1,761,138 Lykken June 3, 1930 2,163,649 Weaver July 27, 1939 2,362,142 Lykken et al Nov. 7, 1944 2,392,958 Tice Ian. 15, 1946 2,416,043 Guyer Feb. 18, 1947 2,538,992 Trask Jan. 23, 1951 2,615,637 Bittner Oct. 28, 1952 2,634,915 Fisher et al Apr. 14, 1953 2,704,635 Trask .-L Mar. 22, 1955 2,752,097 f Lecher June 26, 1956 2,774,543 Keller et al -1..- Dec. 18, 1956 2,846,150 Work Aug. 5, 1958 2,861,880 Hannon Nov. 25, 1958

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