US1948609A

US1948609A - Method of pulverizing minerals and similar materials

Info

Publication number: US1948609A
Application number: US587268A
Authority: US
Inventors: Norwood H Andrews; Walter J Willoughby
Original assignee: AMERICAN PULVERIZING CORP
Current assignee: AMERICAN PULVERIZING Corp
Priority date: 1932-01-18
Filing date: 1932-01-18
Publication date: 1934-02-27
Anticipated expiration: 1951-02-27

Description

vMETHOD OF PULVERIZING MINERALS AND SIMILAR MATERIALS Filed. Jam. 1B. 1932 3 Sheets-Shea?l l Feb, 27, 1934. N. H. ANDREWS Er AL METHOD OF PULVERIZING MINERALS AND SIMILAR MATERIALS Filed Jan. 18, 1932 3 Sheets-Sheet 2 Feb. 27;, 3934. N. H. ANREWS ."ET'AL. $948,609

METHOD OP' '.ULVERIZING MINERALS AND SIMILAR MATERIALS Filed Jan., 1a. 1932 s sheets-sheet 3 Patented Feb. 27, 1934 UNITED STATES PATENT oFF-ICE METHOD F PULVERIZING MINERALS AND SIMILAR MATERIALS Application January 18, 1932. Serial No. 587,268 1s claims. (c1. ss-4s) Heretofore it has been proposed to pulverize various minerals by the direct head-on impact of two alined streams of minerals impelled at high velocity against each other by steam or other 5 similar fluids under high pressure, but such methods have been destructive to the apparatuses in which the processes were performed because of the difficulty in maintaining the impacting streams in perfect alinement, due to the expansion and contraction of the parts under the pressures and temperatures to which the apparatus was subjected.

The lack of alinement of the nozzles during the operation was most destructive for that part of the stream of hard'mineral matter which was unchecked by the opposing stream was driven directly against the walls of the impact chamber or against the projecting end of the opposing nozzles, with the result that they were quickly worn or abraded and destroyed. Moreover, the material tubes through which the minerals being pulverized were impelled were also subjected to great wear and required frequent replacement.

We have discovered that some of the parts heretofore deemed essential to an impact pulverizer, may be dispensed with, and even the metal material tubes and the metallic impact chamber in which said tubes were mounted. We have also found that an exact alinement of opposing streams is not so essential as heretofore it has been believed, provided the body or mass of material under treatment be great enough transversely to prevent the material, impelled by the jets, from being driven laterally through the mass against the walls.

We have also found that by retaining and enclosing a relatively large quantity or mass of loose material under treatment, on the bottom and sides thereof so as to form a columnar body of lloose material and by burying a plurality of steam jets Well below the upper free surface of the wall, with the axes of the steam jets in a relatively horizontal plane and all directed to a focal region preferably'at or about the axis of the column, and by discharging steam at high pressure and velocity from said jets, the steam or other suitable fluid under pressure which may be used, will form and maintain in the mass of material at said focal region a virtual impact chamber; will substantially form tubular .passages through the mass of material from the tips of the jets to said focal region which will operate like the metal material tubes heretofore used, said tubular passages being tapering and through which pieces of material to be pulverized will be driven in a stream to the point of impact of said impact chamber; and will even force through the material, and maintain, a substantially clear passage, extending vertically from the focal or impact chamber to the upper free surface of the mass. Through this last-mentioned passage (normally vertical through the mass and directly over the impact chamber) all of the material which leaves the impact chamber or cavity comprising dust and tailings is impelled at a high rate of speed upwardly as a 'uni-directional stream and is discharged into an initial separator directly over the mass in the material chamber Where a separation of the dust from the heavier particles or fines maytbe effected, the heavier fines falling gravitationally back onto the top of the mass of material being treated, for retreatment or further pulverization andthe dust being carried away floating in the stream of steam passing through and out of the separating chamber.

We have further discovered that a practical and substantial pulverization of a restrained mass of loose material can also be effected in a similar way, by the action of one or more pairs or sets of substantially opposed jets, the axes of which pairs being parallel, and further that a substantial pulverization of such a confined mass of loose material can be effected by one jet or a plurality of jets disposed parallel to each other and without the use of opposing jets, and without an independent delivery tube, provided the mass, in the direction of the discharge from the jets, is deep or thick enough to prevent the pieces, impelled at high velocity, from being driven through the mass against the restraining Wall and provided the distance between the surface level of the mass and the axes of the jets is not so great that the steam cannot force its way up through the mass and form and maintain a virtual delivery tube, the walls of which are composed of the material itself.

The ob-ject of the present invention is to Vsimplify the process of pulverizing minerals and similar materials by impact, by forming and maintaining within a confined body of loose material, under treatment, a virtual impact chamber at a focal point or region within the mass, by discharging into the mass a plurality of opposed jets of dry steam under high pressure and having a high velocity, all the jets being directed to said focal point or region Within the mass, from which chamber all the material is expelled by the steam after impact in a unidirectional stream, upwardly directed, and of high velocity, and by effecting a separation of the heavier particles from the sumciently pulverized particles in an expansion chamber immediately above the level of the free upper surface of the material under treatment and of which said free upper surface forms the bottom of the expansion or primary separation chamber, whereto the heavier particles gravitationally fall in said separation chamber to the mass of material under treatment and are re-subjected to the pulverizing action of the jets, the suiliciently pulverized particles being floatingly carried out of said chamber by the current of steam filling said chamber.

A further object of this invention is to utilize the material under treatment in such a way that the said material forms the wall of the impact chamber in order that the impact of the pieces impelled at high velocity against the walls of said chamber after the impact of the streams will produce a further reduction of the material to powder.

A further object of this invention is to provide a process wherein minerals and similar substances may be pulverized by impact by projecting steam at high temperature and velocity into a loose mass of material to be pulverized but restrained at the sides and bottom thereof even when the jets are not opposed and are not circularly arranged or directed to a common focus, provided the restrained mass is thick enough, in a direction in which the jets project, to deflect the stream upwardly through the mass to the upper unrestrained surface of the mass under treatment forming within the mass virtual delivery tubes, the walls of which are composed in the material under treatment.

A further object of this invention is to make, when so desired, such as iron dust, foreign to the material being treated, the impact being wholly between the pieces of the material under treatment. When metal material tubes and metal impact chambers are used as in the impact pulverizers heretofore constructed, those parts are subjected to so much abrasion that an impact pulverizer is unsuited to the pulverization of some minerals, such as certain pigments wherein even a trace of iron would affect and change the tint of the product.

A further object is therefore to provide a process which can be practiced without the use of metal or other material foreign to the mineral under treatment, at points where such metal would be subjected to substantial abrasion.

Further objects of this invention will appear in. the specification and claims below.

In the drawings forming a part of this specification and in which the same reference figures are employed throughout the various views to designate the same parts,

Fig. 1 is a vertical central section of one form of apparatus which is adapted for the performance of the process, comprising the present inventon;

Fig. 2 is a horizontal transverse section of the same on the line 2--2 of Fig. 1;

Fig. 3 is an apparatus similar to that shown in Fig. 1 but in which the metal delivery tube, shown in Fig. 1, is omitted;

In Figs. 4 to 9 are diagrammatically illustrated several modified processes embodying the invention. In Fig. 4 is shown a modified apparatus, similar to that shown in Fig. 1 but employing two parallel pairs of opposed jets;

Fig. 5 indicates an apparatus Similar 110 that shown in Fig. 4 but wherein the metal delivery tube is omitted;

Fig. 6 is a horizontal sectional view on the line 6--6 of Figs. 4 and 5:

Fig. 'l indicates a modification wherein the jets are not opposed streams;

Fig. 8 shows a modification wherein the metal delivery tube is omitted;

Fig. 9 is a horizontal sectional view on the lines 9-9 of Figs. 'I and 8; and

Fig. 10 is a fragmentary diagrammatic view in horizontal cross-section indicating the general shape of the virtual impact chamber when op-` posed jets are a little out of alinement.

Referring rst to the form of apparatus illustrated in Figs. l and 2, the pulverizer comprises a circular steam header 1 which is provided with a continuous circular passage 2. Superheated steam at high pressure is delivered by a pipe 3, controlled by a valve 4, to the annular passage 2 of the circular steam header 1. Also communieating with the chamber or passage 2 is a circular series of steam jets or nozzles 5 all directed inwardly substantially to a focus 6 at the center of the circular series of jets, the jets being preferably spaced equidistant from each other and arranged with their axes substantially in a common horizontal plane.

The apparatus is preferably provided with a bottom plate or closure 7 which in turn is preferably provided with a hole 8 closed or covered by a pan 9 bolted thereto and which, during the operation of the apparatus remains full of the loose material under treatment as will be referred to again below.

Extending upwardly from the circular header l is a cylindrical housing 10, the upper end of which is substantially closed by a cover or closure 11 preferably tapering upwardly inwardly to a cylindrical throat 12 which in turn communicates with the lower end of a separator 13. The throat 12 is provided with a valve or damper 14 by which the flow of steam and dust from the housing 10 into the separator 13 may be regulated and controlled.

Mounted within the housing 10 and preferably concentric with respect thereto is a delivery tube l5, the lower end of which is located alittle above the focus 6 of the axes of the jets and the upper end of which extends well up into the upper portion of the housing 10. This delivery tube l5 may be rigidly supported in any suitable manner, as by brackets 16 having their outer ends secured to the inner surface of the housing 10 and their inner ends rigidly secured to the outside of the delivery tube 15. The upper end of the tube 15 is alsopreferably provided with a baille or impact plate 17, of hard metal or of iiint, held separated well above the upper end of the delivery tube 15 by supporting rods or brackets 18.

The apparatus also is preferably provided with a chute or feed tube 19 extending through the wall of the housing 10 and through which the material 20 to be pulverized is continuously delivered. The upper surface 21 of the material 20 14C in the housing 10 is maintained at a substantially constant level between the inner wall of the housing 10 and the outer wall of the deliv ery tube 15.

To insure a constant downward travel of the 14.3 material 20 within the housing 10 and to keep the top surface 21 of the material approximately level, we preferably provide a circular distributing member 22 supported near its periphery by a ring-like seat 23 secured to the inner surface i5( of the housing 10, said 'member 22 being provided with teeth 24 adapted to mesh with the teeth of a driving pinion 25 mounted on ashatt 26 journaled outside of the housing 10, the pinion 25 passing through a slot in the housing 10 to engage the teeth 24 of the distributing member 22. This distributing member is provided with a circular series of openings 28 therethrough, one edge of each opening being provided with a vane 29 projecting downwardly.

The distributing member 22 also has a circular opening 30 slightly spaced from the outer surface of the delivery tube 15 and through the said delivery tube 15 extends vertically. So mounted the member 22 is slowly rotated.

Above the distributing member 22 is an inwardly and downwardly flaring or tapering flange 27 secured to the interior of the housing at its upper end and having its lower end overlying the upper surface ofthe periphery of the distributing member 22 for the purpose of preventing the material 20 from flowing into the teeth 24 of the distributing member 20 and for thus keeping the engagement of the said teeth with the pinion 25 clear of said material 20.

In the practice of the process of this invention, sand, coal or other mineral matter to be pulverized, is admitted into the housing 10 through the chute 19 and the distributing member 22 is slowly rotated by the pinion 25 until the housing 10 is filled substantially to the level of the upper edge of the opening through the chute 19. The lower portion of the housing 10 then forms a material chamber 10a and the upper part of the housing 10 above the level of the upper surface 21 of the material 20 constitutes an uptake or primary separating or expansion chamber 10b, the upper end of the delivery tube 15 extending well into the uptake chamber 10b and above the upper surface 21 of the material 20 which forms the floor of vthe said primary expansion chamber 10b.

Superheated steam at high pressure and temperaure is supplied to the jets or nozzles 5 by opening the valve 4. The openings at the discharge ends of the jets or nozzles 5 are small and the dry steam at high pressure issues therefrom into the body of material 20 at a very high velocity with the result that it drives into the mass and almost immediately forms and maintains in the said mass of material 20 a virtual impact chamber 31 in the focal region at and around the true focus 6 of the jets; forms and maintains substantially clear tapering passages 32 extending from the tips of the nozzles 5 respectively to the virtual impact chamber 31; and drives the material immediately after impact upwardly at a high rate of speed as a stream of steam and rapidly moving pieces of solid matter through the delivery tube 15 and against the baffle or impact plate 17 which is preferably made of flint or hard steel. After its impact against the baille or plate 17 the stream of material and steam discharges substantially horizontally between the brackets or supports 18 into the up- 4take chamber 10b wherein the velocity of the steam issuing from the delivery tube or pipe 1'5 is greatly reduced by reason of the expansion of the steam from the pipe 15 into the relatively large chamber 10b. j

This uptake chamber l()b therefore forms a primary separator by means of which the particles of material which have been suiliciently finely comminuted by reason of their impact in the impact chamberand against each other in 'i their travel through the delivery tube 15 and by be floated away on the upwardly moving current of steam in the chamber 10b fall by gravity and come to rest upon the upper surface 21 of the material 20 filling the lower part of the housing 10 or the material chamber 10B.

We have found that the material which is impelled by the jets issuing from the nozzles 5 is mainly supplied to the virtual material tubes 32 from points at or about the tips of the nozzles 5 and that it is that material which is impelled by the high velocity jets of steam through the virtual material tubes or tapering passages 32 into violent impact with like streams impelled by the other jets to the same focal point 10C 6. The quantity of steam so delivered by the jets 5 and the pressure at which it is supplied immediately forms in the body of the material 20 the virtual impact chamber 31 whence, after impact, the impinging material has but one direction to follow, to wit, upwardly through the delivery tube 15. It is true that below the plane of the axes of the jets the impinging material tends to drive downwardly against the mass of material and where it forms a chamber extending a little below the plane of the axes of the jets 5, but a balanced condition is almost immediately attained, a constant layer of unpulverized material is maintained over the pan 9 and substantially all the material after impact is swept or impelled or driven in a single direction, and that upwardly, through the delivery pipe 15 whence it strikes after impact against the plate or baille 17 and then passes substantially horizontallyv into the uptake chamber l0b where the initial separation of the tailings from the dust is effected. Thetailings and heavier particles fall gravitationally back to the surface 21 of the mass of material being treated in the pulverizer and thus travel slowly downwardly under the ac 1-5 tion of gravity and the distributing member 20 to points adjacent the nozzles 5 by which in time they are again caught or are picked up by the stream of steam issuing from the nozzles and are further pulverized by their impact with opposing streams. As the level 21 of the mass of material in the material chamber lowers slightly, as the material is pulverized by the jets and floats out of the uptake chamber 10b, the upper edge of the opening of the chute 19 becomes uncovered slightly, whereupon more of fresh material gravitationally flows into the material chamber 10. Thus the level of the upper surface 21 of the material in the material chamber 10Il is maintained substantially constant and thel distance from the plane of Athe axes of the jets to th e free upper surface of the mass is substantialy ly unchanged during the operation.

Of course, seldom do two pieces of material driven by opposed streams of steam at high pressure strike absolutely head-on squarely against each other, but after impact they may strike against the side and bottom walls of the impact chamber and may momentarily have an orbital movement around the focus 6, but the steam in the impact chamber can only emerge from the impact chamber by moving upwardly out through the delivery tube 15 since the mass of loose material is confined at its bottom and sides. The walls of the virtual material tubes 32 and the walls of the virtual impact chamber 31 are thus composed of the very material which is being pulverized and any impact of the flying material against the walls of the tubes or passages 32 or against the walls of the impact chamber 31 or against each other in their travel or in their impact with opposing streams all contributes to the rapid comminution and reduction of the particles to a powdered condition. The reduction of the material to a powdered condition is relatively rapid and that which has been reduced to a sufficiently fine powder is borne away as fast as it is formed up out of the uptake chamber 10b and into the separator 13 where a further finer separation of the coarser from the iiner particles may be effected when it is desirable to produce a very finely powdered product.

When the apparatus is used for pulverizng anthracite coal, for which this process is particularly adapted, the separator 13 may be dispensed with and the stream of dust and steam passing through the throat 12 may be conducted through a suitable tube and conveyed directly to the iirebox of a boiler or other apparatus in which the powdered coal' is to be burned, thus eliminating entirely the necessity of first .collecting the powdered coal, then transporting it to a storage bin and then conveying it by a suit' able feeding apparatus to the fire box. This intermediate collecting, handling and storing of the powdered product may thus be entirely dispensed with in the practice of this invention by feeding the pulverized coal directly from the pulverizer to the boiler in which it is to be consumed.

In the modification shown in Fig. 3, the metal delivery tube 15 is omitted and the baille or deiiector 1'? in the uptake chamber is conical and depends from the top or closure 11 thereof, being rigidly supported by rods or brackets 18. 1n other respects the construction is substantially identical with that shown in Figs. 1 and 2.

In this apparatus the steam at high pressure is projected into the mass of material 20 from the jets 5 toward a common center or focal region and they form and maintain the tubular tapering passages 32 and the virtual impact chamber 31 as they do in the apparatus shown in Fig. 1. But the steam at or about the focal point 6 in the mass is under high pressure and is moving at high velocity. Since the mass of loose material is restrained and confined at the bottom and sides and cannot yield in those directions, but is unrestrained on its upper side, the steam discharges from the impact chamber 31 upwardly through the unrestrained upper surface 21 and forms and maintains a tubular passage 15a straight through the mass, thus forming a virtual delivery tube 15a, functioning like the tube 15, shown in the construction of Fig. 1, in that, through it, all of the material, both fine and coarse, after impact, is violently impelled at high velocity against the baule or deflector 1'7xi in the primary separating chamber l0b over the material in the material chamber 10a whence it is deflected horizontally radially, and a primary separation of the dust from the insufficiently pulverized particles is effected, the heavy particles falling gravitationally to the top 2l of the mass in the material chamber 10b for retreatment, while the light, sufficiently pulverized particles are carried by the current of steam upwardly between the bars 18 and out through the throat 12.

We have found that it is not absolutely necessary to have the jets 5 in exact alinement or to direct them to an exact focal point, provided the columnar body of loose material in the material chamber is thick enough horizontally to prevent the steam from driving straight through it to the opposite side wall of the cylindrical housing 10 or to the opposite side of the header 1. (See Fig. 10).

If the streams are directed a little to one side of the focus no harm would ensue for the thickness of the mass of the material between the virtual impact chamber 31c and the housing l0 is sufficient to stop the rapidly driven pieces of material before they reach the wall. This is true even when only two substantially alined and opposed jets are used instead of more than two as shown in the drawings. Where three or more jets are employed any similar lack of alinement of a jet with the focus 6 does not detract from the efficiency of the device. The shape of the virtual chamber 31c may become somewhat elongated and the rapidly moving pieces of material in the impact chamber may be subject to a circular or orbital movement around the focal point, but such motions and the impact of the pieces against each other and against the wall and bottom of the impact chamber 3lc and against the walls of the virtual uptake delivery tube 15 could only tend to supplement and accelerate the comminution of the pieces and to increase the eilciency of the apparatus by effecting a more rapid pulverization of the mass as a whole.

But Where the mass of material in the material chamber is backed and retained by a rigid wall or by a rigid bottom plate the velocity of the streams of material, particularly after impact, is not generally sufficient to drive the pieces deeply into the mass, particularly if the outlet from the impact chamber is provided by the tube 15, or after the virtual delivery tube 15 has been formed, vertically therefrom. It is for this reason that the relatively thin layer of sand or loose material between the bottom of the virtual irnpact 31 and the closure or pan 9 is ample to prevent the flying pieces from driving through it to the metal closure.

Having thus described with considerable particularity two types of apparatuses in which the present invention may be practiced, a brief description of further modifications of the process with diagrammatic reference to the apparatus will now suffice.

In Figs. 4 and 5 are illustrated diagrammatically two modified arrangements wherein a pair of jets 5 5 are alined as distinguished from being directed to a common focal point, and wherein are employed four jets arranged as two pairs of opposed alined jets 5-5-5-5 all directed substantially to a control or focal region, all within a housing 10' which may be of rectangular or of any other suitable shape instead of circular in horizontal cross-section.

Referring to the modification shown in Figs. 4 and 6 steam issuing from each pair of alined jets 5--5 forms, in the mass 20, the same virtual material tubes 32 that they do in the apparatus shown in Figs. 1 and 3, but when the pairs of alined jets are relatively close to each other as is indicated in Fig. 6 they form a virtual impact l chamber 31 which is elongated and in which the material issuing from one pair of opposed jets 5 5, and after impact, some of the material is thrown toward the axis of the cooperating pair of alined jets 5 impacting against the material similarly projected by that other pair of alined jets 5-5 thus effecting a further pulverization of the product by impact, as is clearly shown by the arrows in the impact chamber 31 shown in Fig. 6.

In this apparatus is shown a delivery tube 15b which may be supported as shown in Fig. 1, but

which will be elongated transversely to conform to and overlie the elongated impact chamber 31a. 15a is preferably providedv a suitable deflector 171 in the primary separation chamber 10b to deflect the material laterally after its impact with the deector 17h, and the heavier particles fall in the separation chamber 10b to the surface 21 of the mass 20 in the material chamber 10a.

In thismodiiication the lighter particles are carried by the steam lling the separation chamber 10b upwardly out through the throat 12.

In Fig. 5 the arrangement is exactly like that shown in Fig. 4 except that the tube 15b is omitted. It therefore bears the same relation to the apparatus shown in Fig. 4 that the arrangement shown in Fig. 3 bears to that in Fig. 1. In this case the steam leaving the impact chamber 31a forms a virtual delivery tube 15c extending vertically upwardly through the mass 20 from the impact chamber 31 through this passage 15c all the material after impact is ejected as a stream at high velocity against the deflector 17h, as it does in the apparatus shown in Fig. 3.

The horizontal section through the axes of the jets 5-5-5--5, on the line 9-9 through the two apparatuses shown in Figs. 4 and 5 are identical and are shown in Fig. 9.

In Figs. 7 to 9 inclusive are shown two further modications of our improved process to demonstrate the fact that when the width or thickness of the constrainedmass of loose material 2O is sufficient, to preclude pieces impelled by the jets 5 from completely penetrating the mass to the opposite wall of the housing 10, it may not be necessary to use opposing streams of material impelled by opposing jets.

Thus in Fig. l the casing or housing 10" may be rectangular and the jets 5--5--5-5 may be arranged to discharge steam in the mass 20 parallel to each other and in the same horizontal direction. In this case each jet will form through the mass a virtual material tube 32 as in the previously described modifications, but as the stream approaches the opposite wall of the casing 10 it will be opposed by the material 20 adjacent that wall, and the impact chamber 31b4 will be formed where the stream of material propelled through the material tube 32 is checked against the material adjacent the opposed wall. If, therefore, a delivery tube 15b like that shown in Fig. 4 be supported directly over the impact chamber 31b as shown in Fig. 7 all the material after impact will be forced by the steam delivered from the jets 5 upwardly through the delivery tube 15b against the deflector 17 and thence horizontally into the separator chamber 10b in which the heavy particles will fall to the bottom of the chamber and consequently to the surface 21 of the mass 20 for retreatment, and the lighter particles will be floated out of the chamber 10b through the throat 12 either to such Above the upper end of the delivery tube a. separator as ls indicated in Fig. 1 or to any other suitable place.

In Fig. 8 the apparatus is exactly like that shown in Fig. 7 except that the upwardly directed delivery tube 15b is omitted and the steam from the impact chamber 31b forms and maintains a virtual delivery tube lthrough the material itself and through the delivery tube all the material after impact is impelled upwardly against the deflector 17c as in Fig. '7.

In all the various modifications of this invention the steam from the jets 5 is discharged at high pressure and at high velocity directly into the mass of loose material to be pulverized, the loose material being restrained from movement in all directions but one, that one preferably being the vertical direction through the top surface of the mass; the velocity of the steam projected into'the mass is so great that it forms and maintains virtual material tubes through which material of the mass is impelled at highA speed into a virtual impact chamber; the steam issuing from the jets at high velocity and pressure forms within the mass a virtual impact chamber in which the impact is between streams of material issuing from opposed jets or with the Wall of the impact chamber itself; after leaving the impact chamber the steam delivered thereto drives substantially all the material (both ne and coarse) out of the impact chamber upwardly, through either an actual delivery tube extending Yfrom the impact chamber to a point well above the level of the free surface of the mass, or through a virtual delivery tube formed by the steam itself driving through the mass upwardly from the impact chamber; the upper surface of the mass of loose material under treatment forms the lower wall of a primary separation chamber into which the steam from the delivery tube expands and in which the speed of the steam is reduced sufliciently to permit the heavier particles to fall by gravity to the upper surface of the mass for retreatment; and the light sufficiently ground particles or dust are floatingly borne by the steam filling the separator chamber out of the separator forV a further separation or for collection or to any desired place or position for use or storage.

It is not to be understood that applicants regard the modifications of the process, particularly as illustrated in Figs. 'I and 8, to be as emcient, generally speaking, as when carried out by such constructions as are indicated in Figs. 1 to 3, which permit of the use of a large number of jets directed to a common focal point wherein a violent impact is attained and a rapid reduction of hard materials to a very fine powdery condition is easily effected. But the process may be carried out with a plurality of jets arranged in parallelism, in the'manner indicated in Fig. 9 when relatively soft material is to be pulverized and the degree or neness to which the material is to be reduced is not an essential consideration:

From the foregoing disclosures, it is apparent that many changes may be made and that many details may be varied in applying the principle of our invention to the pulverization by impact of various materials of varying degrees of hardness and in the production of powders of differing degrees of neness, and it is not our intention to limit our invention to the exact steps or to the precise procedures herein disclosed so long as such changes and variations fairly fall within the spirit and scope of the appended claims.

Having thus described our invention, what we claim and desire to protect by Letters Patent of the United States is:

1. The method of pulverizing minerals and the like, which consists in confining the mass of loose mineral matter to be pulverized by enclosing the said mass on the bottom and sides thereof and discharging into the mass a plurality of substantially opposed streams of a gaseous fluid at high velocity, the axes of said streams being located at a substantial distance below the freeupper surface of said mass and substantially meeting at a focal point or region within said mass, the pressure and velocity of the said iiuid being suficient to form and maintain within the mass at the said focal region a virtual impact chamber, the side walls and bottom of which are composed of the loose material of the mass and to form and maintain substantially tubular passages through the mass from the point where the said uid is discharged into the mass to the said impact chamber through which tubular passages some of the loose material of the mass is impelled by said streams of said fluid at high speed into impact in said impact chamber with similar opposed streams.

2. The method. of pulverizing minerals and the like, which consists in confining the mass of loose mineral matter to be pulverized by enclosing the said mass on the bottom and sides thereof and discharging into the mass a plurality of substantially opposed streams of a gaseous uid under pressure at high velocity, the axes of said streams being located at a substantial distance below the free upper surface of said mass and substantially meeting at a focal point or region within said mass, the pressure and velocity of the said fluid being sufficient to form and maintain in the mass at the said focal region a virtual impact chamber, the said walls and bottom of which are composed of the loose material of the mass and to form and maintain substantially tubular passages through the mass from the point where the said iiuid is discharged into the mass to the said impact chamber through which tubular passages some of the loose material of the mass is impelled by said streams of said fluid at high speed into impact in said impact chamber with similar opposed streams, the pressure and Velocity of the said fluid after the impact of opposed streams in said impact chamber being operative to impel all of the material leaving the impact chamber after impact in one direction at high velocity, said direction being upwardly at right angles to the plane of the axes of said streams.

3. The method of pulverizing minerals and the like, which consists in confining the mass of loose mineral matter to be pulverized by enclosing the said mass on the bottom and sides thereof and discharging into the mass a plurality of substantially opposed streams of a gaseous fluid under pressure at high velocity, the axes of said streams being located at a substantial distance below the free upper surface of said mass and substantially meeting at a focal point or region within said mass, the pressure and Velocity of the said uid being sufficient to form and maintain in the mass at the said focal region a virtual impact chamber, the said walls and bottom of which are composed of the loose material of the mass and to form and maintain substantially tubular passages,

through the mass from the point where the said uid is discharged into the mass to the said impact chamber through which tubular passages some of the loose material of the mass is impelled by said streams of said uid at high speed into impact in said impact chamber with similar opposed streams, the pressure and velocity of the said iiuid after the impact of opposed streams in said impact chamber being operative to impel all of the material leaving the impact chamber after impact in one direction at high velocity, said direction being upwardly at right angles to the plane of the axes of said streams, into an expansion and separator chamber immediately above said mass of material under treatment into which the heavier particles fall gravitationally to the upper free surface of said mass and from which the finely pulverized dust is carried away by said fluid.

4. The method of pulverizing minerals and the like, which consists in confining the mass of loose mineral matter to be pulverized by enclosing the said mass on the bottom and sides thereof and discharging into the mass a plurality of substantially opposed streams of a gaseous fluid under pressure at high velocity, the axes of said streams being located at a substantial distance below the free upper surface of said mass and substantially meeting at a focal point or region within said mass, the pressure and velocity of the said uid being suflicient to form and maintain in the mass at the said focal region a virtual impact chamber, the said walls and bottom of which are composed of the loose material of the mass and to form and maintain substantially tubular passages through the mass from the point where the said fluid is discharged into the mass to the said impact chamber through which tubular passages some of the loose material of the mass is impelled by said streams of said fluid at high speed into impact in said impact chamber with similar opposed streams, the pressure and velocity of the said uid after the impact of opposed streams in said impact chamber being operative to impel all of the material leaving the impact chamber after impact in one direction at high velocity, said directionI being upwardly at right angles to the plane of the axes of said streams, then reducing the speed of the stream of said fluid leaving said impact chamber by expanding it into a separating chamber, the bottom of which is formed by the top surface of the mass of material under treatment whereby the insufficiently pulverized heavier particles fall gravitationally to the top of said mass under treatment and the sufficiently small dust-like particles are borne away by said iiuid as it passes through said separator chamber.

5. The method of pulverizing minerals and the like, which consists in confining the mass of loose mineral matter to be pulverized by enclosing the said mass on the bottom and sides thereof and discharging into the mass a plurality of substantiallyvopposed streams of a gaseous iiuid under pressure at high velocity, the axes of said streams being located at a substantial distance below the free upper surface of said mass and substantially meeting at a focal point or region within said mass, the pressure and velocity of the said fluid being suflicient to form and maintain in the mass at the said focal region a virtual impact chamber,

the said walls and bottom of which are composed of the loose material of the mass and to form and 'maintain substantially tubular passages through the mass between the point where the said fluid is discharged into the mass to the said impact chamber through which tubular passages some of the loose material of the mass is impelled by said streams of said fluid at high speed into impact in said impact chamber with similar opposed streams, the pressure and velocity of the said iiuid after the impact of opposed streams in said impact chamber being also operative to form and maintain a substantially clear passage through the mass from the said impact chamber to the upper free surface thereof through which all the material after impact is impelled in a stream of said fluid of high velocity in one direction, said dlrection being vertically upwardly from said impact chamber.

6. The method of pulverizing minerals and the like, which consists in conflning the mass of loose mineral matter to be pulverized by enclosing the said mass on the bottom and sides thereof and discharging into the mass a plurality of substantially opposed streams of a gaseous fluid under pressure at high velocity, the axes of said streams being located at a substantial distance below the free upper surface of said mass and substantially meeting at a focal point or region within said mass, the pressure and velocity of the said fluid being sufficient to form and maintain in the mass at the said focal region a virtual impact chamber, the said walls and bottom of which are composed of the loose material of the mass and to form and maintain substantially tubular passages through the mass from the point where the said fluid is discharged into the mass to the said impact chamber through which tubular passages some of the loose material of the mass is impelled by said streams of said iiuid at high speed into impact in saidimpact chamber with similar opposed streams, the pressure and velocity of the said iiuid after the impact of opposed streams in said impact chamber being operative to impel all of the material leaving the impact chamber after impact in one direction at high velocity, said direction being upwardly at right angles to the plane of the axes of said streams, the depth of the material above the plane of the axes of said streams being maintained substantially constant by the slow addition thereto of fresh material to be pulverized.

7. The method of pulverizing mineralsand the like, which consists in confining a mass of loose mineral matter to be pulverized by enclosing the mass on the bottom and sides thereof and discharging, through a small orifice, into the mass, a stream of a suitable iiuid under pressure land at high velocity, the axis of said stream being substantially horizontal and located at a substantial distance below the upper free surface of said mass, the pressure and velocity of the said iiuid being sufficient to form and maintain substantial tubular passages in the mass through which some of the loose material of the mass is impelled at high speed by said stream of said fluid into impact with other pieces of the material of the mass in said impact chamber, to reduce said pieces to powder by impact.

8. The method of pulverizing minerals and the like, which consists in confining a mass of loose mineral matter to be pulverized by enclosing the mass on the bottom and sides thereof 'and dischargingthrough a relatively small orifice into the mass, a stream of a suitable fluid under pressure, the axis of said stream being substantially horizontal and at a substantial distance below the upper surface of said mass, the pressure and velocity of the said iiuid being sufficiently high to form and maintain within said mass a virtual impact chamber, the walls and bottom of which are composed of the loose material of the mass, to form a straight tubular passage through the mass from said orifice to said impact chamber and to form a passage from said impact chamber to the surface of said mass through which the pieces of the mass are impelled vertically upwardly by said iiuid after impact in said impact chamber.

9. The method of pulverizing minerals and the like, which consists in confining the loose mineral to be, pulverized by enclosing the mass on the bottom and sides thereof and discharging through a relatively small orifice, into the mass, a stream of a suitable iiuid under pressure, the axis of said stream being located at a substantial distance below the upper free surface of said mass, the velocity of the said iiuid being high and suficient to form and maintain in the mass a virtual impact chamber, the walls and bottom of which are composed of the loose material of the mass; to form and maintain substantial virtual passages through the mass from the point where the said iiuid is discharged into the mass; to the said virtual impact chamber through which tubular passage some of the loose material of the mass is impelled by said stream of said fluid at high speed into said impact chamber; and to also form and maintain a vertical passage from said impact chamber through and to the upper surface of said mass through which vertical passage after impact are impelled at a high rate of speed by and in said iiuid substantially all the contents of said impact chamber after impact therein.

10. The method of pulverizing minerals and the like, which consists in confining the loose mineral to be pulverized by enclosing the mass on the bottom and sides thereof and discharging, from an orifice, into the mass, a stream of a suitable iiuid under. pressure, the axis of said stream being substantially horizontal and at a substantial distance below the upper free surface of said mass, the velocity of the said iiuid being ample to form and maintain in the loose mass a virtual impact chamber, the Walls and bottom of which are composed of the loose material of the mass and to also form and maintain substantial virtual passages through the mass from the point where the said iiuid is discharged into the mass to the said virtual impact chamber through which tubular passage some of the loose material of the mass is impelled by said stream of said iiuid at high speed into said impact chamber, the pressure and velocity of the said fluid after impact in said impact chamber, being operative to impel all of the material out of said chamber as a stream moving at high velocity upwardly through the mass, and effecting a separation of the tailings from the dust immediately over said mass being treated whereby the tailings by gravity are returned directly to said mass for retreatment.

11. The method of pulverizing minerals andV the like, which consists in confining the loose mineral to be pulverized by enclosing the mass on the bottom and sides thereof and discharging through a relatively small orifice, into the mass, a stream if a suitable fluid` under pressure, the axis of said stream being located at a substantial distance below the upper free surface of said mass and substantially parallel thereto, the pressure and velocity of the said fluid being ample to form and maintain in the loose mass a virtual impact chamber, the walls and bottom of which are composed of the loose material of the mass and to also form and maintain substantial virtual passages through the mass from the point where the said fluid is discharged into the mass to the said virtual impact chamber through which tubular passage some of the loose material of the mass is impelled by said stream of said fluid at high speed into said impact chamber, the pressure and 'velocity of the said fluid after impact in said impact chamber, being operative to impel all of the material out of said chamber as a stream moving at high velocity upwardly through the mass, and effecting a separation of the tailings from the dust above the level of the mass of material under treatment and gravitationally returning said tailings to said mass for further pulverization by impact.

12. The method of pulverizing mineralsan the like, which consists in conning a mass of loose pieces of mineral matter to be pulverized on the bottom and sides thereof and discharging into the mass, a plurality of substantially opposed streams of a suitable fluid at high velocity, the axes of said streams being substantially horizontal and located at a substantial distance below the free upper surface of the mass under treatment, the pressure and velocity of the fluid being sufcient to form and maintain within the mass at the focal region a virtual impact chamber the side walls and bottom of which are composed of the loose pieces of the material of the mass, and to form and maintain substantially tubular passages through the mass between the point where the uid is discharged into the mass to the said impact chamber and through which tubular passage some of the loose material of the mass is impelled by the said streams of uid at high speed into impact in said impact chamber with similar opposed streams.

13. The method of treating minerals and similar hard substances which consists in impelling, in a body of loose material under treatment opposed streams of said material against each other at high velocity, said streams being impelled each by a jet of dry gaseous fluid under high pressure, the axes of said streams being substantially directed against each other to a focal region in an impact chamber in said material, said axes lying in a substantially horizontal plane, all materials after impact being directed outwardly from said impact chamber in a single stream normally moving at a high velocity in a direction upwardly at right angles to said common plane, impelled by the expanding uid from said jets after impact, and to a position over the mass of loose material being treated and then reducing the velocity of said stream issuing from said impact chamber and separating the tailings therefrom at a point above the level of the material being treated by said jets and gravitationally returning substantially all said tailings directly to said mass of material for retreatment by said jets.

NORWOOD H. ANDREWS. WALTER J. WILLOUGHBY.

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