US3184169A - Apparatus for pneumatically pulverizing material - Google Patents

Description

y 1965 L. s. FRIEDMAN ETAL 3,184,159

APPARATUS FOR PNEUMATICALLY PULVERIZING MATERIAL Filed March 29, 1963 :s Sheets-Sheet 1' INVENTORS LAWRENCE s. FRIEDMAN IRA L. FRIEDMAN KENNETH c. ZAGIELSKI Q BY LEO A. ADAMS ATTORNEY y 1965 L. s. FRIEDMAN ETAL 3,184,169

APPARATUS FOR PNEUMATICALLY PULVERIZING MATERIAL Filed March 29, 1963 3 Sheets-Sheet 2 3 7 INVENTORS I I I LAWRENCE 5. FRIEDMAN IRA L. FRIEDMAN KENNETH C.ZAGIELSKI 5 BY LEO A. ADAMS ATTORNEY y 1965 L. s. FRIEDMAN ETAL 3,184,159

APPARATUS FOR PNEUMATI CALLY PULVERIZING MATERIAL Filed March 29, 1963 3 Sheets-Sheet 3 7/z 4 &\\\\\\\\\\\\\\\ 'lllllmlll M llll INVENTORS LAWRENCE 5. FRIEDMAN IRA L. FRIEDMAN BYKENNETH C. ZAGIELSKI LEO A. ADAMS A TTOR/VEV United States Patent 6 F 3,184,169 APPARATUS FOR PNEUMATICALLY PULVERIZENG MATERIAL Lawrence S. Friedman, 9 Nymph Road, West Orange, Ni; Ira L. Friedman, Sill) S. Center St., Orange, Ni; Kenneth (I. Zagielsld, 3d Osborne Terrace, Packanack Lake, Ni; and Leo A. Adams, 208 Phelps Ave, Cresskill, NJ.

Filed Mar. 29, 1963, Ser. No. 266397 7 Claims. (Cl. 241-4ll) Our invention relates to reducing the size of materials generally and specifically to apparatus for pneumatically pulverizing friable and abrasive materials.

In the metallurgical arts, it is frequently desirable to reduce the particle size of various relatively hard and abrasive metals, metal alloys or metallic compounds to a powder wherein each particle has a diameter of approximately 44 microns or less. Ordinary methods of crushing and grinding cannot be employed for extremely abra sive materials, particularly if the final product must be free from contaminants. Moreover, known methods and apparatus cannot efficiently reduce particle size to the aforementioned micron range.

The sand, concrete and coal industries have previously employed pneumatic techniques for pulverizing silicon compounds and coal. However, these materials are not particularly abrasive nor must the final product be free from contaminants. In the powder metallurgical arts wherein scrap metal such as tungsten carbide must be pulverized to the micron or submicron range, known methods and apparatus cannot be employed from the rapid production of large quantities of such a line powder. it has been found that such hard and abrasive compounds as tungsten, tungsten carbide, tungsten carbide cobalt and the like rapidly wear out portions of the apparatus to the point of structural failure. In addition, the final product must be free from contaminants which is impossible if internal parts of the apparatus are continuously worn away and entrained into the stream of material handled.

Therefore, it is among the objects and advantages of our invention to provide apparatus for pneumatically pulverizing materials in which relatively large particles are entrained in a high pressure, high velocity stream of air passing through a venturi-shaped nozzle to strike an impact plate or shield thereby fracturing the particle by impact.

Another object of our invention is to provide apparatus for pneumatically pulverizing materials in which the blast nozzle is either fabricated of or provided with an internal lining of the material being pulverized, thereby minimizing nozzle wear and eliminating product contamination.

A further object of our invention is to provide apparatus for pneumatically pulverizing materials in which the impact shield is either fabricated of or provided with an external cladding of the material being pulverized thereby minimizing shield wear and eliminating product contamination.

Still another object of our invention is to provide apparatus for pneumatically pulverizing material in which conduits adapted to carry the material under high pressure and at high velocity to the discharge nozzle are either fabricated of or provided with an internal lining of the material being pulverized or of rubber or some suitable material which is substantially unabrased by the material passing therethrough.

Another object of our invention is to provide apparatus for pneumatically pulverizing material in which the exterior of the blast nozzle and the interior of a blast chamber enclosing both the end of the nozzle and the shield are provided with a lining of the material being Eddidhh Patented May 18, 1965 ice pulverized, or of rubber or some suitable material substantially unabrased by the material being pulverized.

Still a further object of our invention is to provide apparatus for pneumatically pulverizing material in which the material is vacuum discharged from the blast chamber, passing through a conduit into a primary classifier and recyeler wherein oversized particles are recycled through the blast nozzle and properly sized and subsized particles are passed into secondary classifiers and collection vessels.

Yet another object of our invention is to provide apparatus for pneumatically pulverizing materials in which new raw material may be either continuously or periodically introduced into the blast chamber under vacuum while the apparatus is in operation.

Yet still another object of our invention is to provide apparatus for pneumatically pulverizing materials in which new material being fed into the blast chamber is filtered to remove excessively oversized particles which might tend to clog the blast nozzle.

These objects and advantages as well as other objects and advantages may be achieved by our invention one embodiment of which is illustrated in the drawings in which:

FIGURE 1 is a side elevational view of our apparatus including input air drying and purification means, input air high pressure accumulators, a primary classifier and recycler, input and recycle storage and feed vessels, the blast chamber and secondary classifiers with collection vessels connected thereto;

FIGURE 2 is a side elevational, cross-sectional view of the blast chamber, the input hopper for new raw material and the blast chamber discharge system;

FIGURE 3 is a top plan view of the apparatus shown in FIGURE 2 with the top of the blast chamber and input feed hopper removed;

FIGURE 4 is a side elevational, cross-sectional view of the nozzle;

FIGURE 5 is a side elevational, partially cross-sec tional view of the blast chamber, nozzle and nozzle feed system.

Referring now to the drawings in detail, our apparatus comprises a compressor system, not shown in the drawings, capable of generating relatively large volumes of air at pressures in excess of 300 psi. The air is delivered from the compressor through conduit 11 to a Van Allen air dryer and purifier 12 which removes substantially all entrained water vapor and oil. The dry, clean, high pressure air then passes through conduit 13 to a pair of high pressure accumulators, respectively 14 and 15, interconnected by means of conduit 16.

The material pulverizing and handling system is closed and comprises generally a pig 17 defining a blast chamber 18, a pressurized recycle feed hopper 19 mounted above and to the rear of the pig 1?, a vacuum storage hopper 2d m ounted immediately above the pressurized feed hopper l9 interconnected thereto through a pressure operated valve 21, and a primary classifier-rccycler 22 mounted immediately above the vacuum storage hopper 20. A secondary cyclone classifier and precipitator 23 and a second secondary cyclone precipitator 2d are connected in series to the primary classifier-recycler 22.

The pig 17 comprises a generally rectangular upper portion 25 having an inverted pyramidal bottom portion 26. The upper portion 25 and pyramidal portion 26 define the blast chamber 18. A generally inverted, partially pyramidal raw material feed hopper 27 is formed on one side of the upper portion 25 of the pig 17. A passage 28 extends between the bottommost tip of the hopper 27 and the blast chamber 13 through one wall 29 of the upper portion immediately adjacent to a conduit 39 which extends from within the blast chamber 18 through one of the inclined walls 31 of the pyramidal portion 26 downwardly to a generally horizontal exhaust conduit 32. A passage, 33 connects the'bottom-most tip of the pyramidal portion 26 of the pig 17 with the exhaust conduit 32. The pig 17 is provided with a top 34 mounted thereon by means of a hinge 35. The top 34 may be securely fastened to the pig 17 by means of the hinged threaded lugs 36 and wing nuts 37. Similarly, the raw material feed hopper 27 is provided with a top 38 mounted to the pig 17 by means of a hinge 39. The top 38 of the hopper 27 is provided with an input feed filter screen 40 adapted to prevent the passage of particles over a predetermined size. As in the case of the top 34 tothe pig 17, the top 38 of the hopper 27 may besecurely fastened in a closed position by means of hinged threaded lugs 41 and wing nuts 42.

The blast nozzle 43 extends through the rectangular portion 25 of the pig 17 adjacent to the conduit 39. The nozzle 43 terminates approximately immediately above the discharge passage 33. An arcuate impact'shield 44 is mounted in general axial opposition to the nozzle 43. The shield 44 is mounted on a threaded bolt 45 extending through the rectangular portion 25 of the pig 17. A pair of nuts 46 and 47 on opposite sides of the rectangular portion 25 of the pig 17 provide means for axially adjusting the position of the shield 44 with respect to the end of the nozzle 43. The axis of the nozzle lies in a generally horizontal plane while the arcuate shield 44 lies in a generally vertical plane.

The nozzle 43 comprises a tubular supporting sleeve 48 made of steel or some other suitable structural material. The sleeve 48 is provided with an external annular rubber cover 49; However, it should be noted that under conditions of extreme abrasion, the rubber cover 49 may be replaced by a cover of the material being pulverized or some other material not subject to abrasion by the material being pulverized. An internal rectangular rubber nozzle mount 50 is seated within the sleeve 48. An internal, venturi-shaped blast nozzle 51 is mounted within the rubber holder 50. A plurality of external annular bands 52 surrounding the holder 56, compressing it inwardly, tightly secures the nozzle 51 in place. In addition, the external surface of the nozzle 51 may be provided with a plurality of projections 53 adapted to seat within the resilient surface of the cover 50. The nozzle 51 is fabricated of the material to be handled by the apparatus as for instance tungsten carbide or the like. In most instances, tungsten carbide will provide a universal nozzle since it is harder and more abrasive than perhaps any other material likely to be used. The nozzle '51 is provided with an internal, generally axial venturi-shaped passage 54 adapted to increase substantially the velocity of the air stream emitted therefrom. V V

The nozzle 43 extends through an opening 55in the rectangular portion 25 of the pig 17. The opening 55 is large enough to tightly accommodate the external rubber cover 49, the cover 49 extending rearwardly to a feed T 56. The external cover 49 is provided with a plurality of holes 57 between the pig 17 and the T 56 to enhance cooling of the nozzle 43. The end of the T coaxial with the nozzle 43 is connected to conduit 58, the opposite end of which is connected through a system of valves to pressure accumulator 15.

The-intersecting conduit 59 of T 56 is connected to pressurized feed hopper 19. The pressurized feed hopper 19 is connected through a pressure actuated valve in its top to a vacuum hopper 20 which is in turn connected to classifier-recycler 22. Conduit 32 extends past discharge passage 33 and rises vertically terminating in a marine type pressure actuated valve 60. Conduit 32 extends on .its opposite end past the discharge passage 33 in the bottom of the pig 17 upwardly to the classifierrecycler 22. Another conduit 61 connects the classifierrecycler 22 to a secondary cyclone classifier and precipitator 23. Classifier-precipitator 23 is connected through conduit 62 to secondary cyclone precipitator 24. Classifier 23 and precipitator 24 are respectively connected through conduits 63 and 64 to final product receiving hoppers, respectively 65 and 66.

In operation, all material is introduced through feed hopper 27 by means of passing it through filter 40. Oversized particles, that is over approximately inch in diameter are filtered out and only subsized particles of inch or less pass into hopper 27. The nozzle 43 is pressurized by opening'an electrically operated timer valve 67 in conduit 58 which passes air into the axial end of T 56. In addition, classifier-recycler 22 is energized creatin g a vacuum therein of substantial degree. Material fed through hopper 27 passes through passage 28 between the upper portion 25 of the pig 17 and the inverted pyramidal section 26. The material is drawn by the vacuum in conduit 32 downwardly through conduit 39 passing upwardly into the classifier-recycler 22. Since all of the material is presumabily toversized, the recycling unit passes it downwardly into hopper 20 which is under vacuum. A pressure sensing valve 69 between the T 56 and the pressurized feed hopper 19 is adapted to detect excess differential in pressure between the nozzle 43 and conduit 32 which occurs when no material is passing through nozzle 43. Valve 69 then closes to depressurize feed hopper 19. Immediately thereafter valve 21 between hopper Ztl and hopper19 opens by means of gravity feeding the material in hopper 21) into hopper 19. The valve 69 then recycles to pressurize hopper 19 closing valve 21. Material falls downwardlythrough valve 69 into the intersecting portion 59 of T 56. Since air is passing through conduit 58 into nozzle 43, the material is entrained in the air stream, passing into the venturi 54 of the internal blast nozzle 53. The venturi passage imparts extremely high velocity particles of material. The material strikes shield 44 with suflicient velocity to fracture it, the particles falling downwardly into the inverted pyramidal section 26 of pig 17. The pig 17, of course, is provided with a lining 70 of the material being pulverized, of rubber or of some other suitable material not subject to abrasion by the material being pulverized. The particles fall downwardly through discharge passage 33 into conduit 32 which is under vacuum. The broken particles are then forced under vacuum upwardly into classifier-recycler 22 where the properly sized, micron or less, material is passed through conduit 61 into a secondary cyclone classifier 23. The oversized particles pass downwardly into hopper 20 for recycling. The pressure dilferential between conduit 32 and the nozzle 43 remains sufiiciently low to maintain valve 69 in an open position so long as material is passing through the T 56 and the nozzle '43-. However, when all of the material has cleared the nozzle 43, the pressure differential increases sufficiently to close valve 69 depressurizing hopper 19 and thereby opening valve 21 to refill the pressure hopper 19 with the recycled material which has previously collected in hopper 2i). Thereafter, the cycle operation occurs as herebefore described until all of the materate the subsized particles into groups of two different sizes. Obviously, in some instances only one cyclone classifier would be necessary and in other cases perhaps more than two would be necessary. Periodically, mate rial which has passed through cyclone classifier 23 and precipitator 24 and collected in vessels 65 and 66 may be withdrawn. It may be desirable from time to time to introduce new material through screen 40 and hopper 27.

This may be done as the operation continues without shutting down the nozzle or any other phase of the apparatus. The hopper 27 will always be subjected to a small negative pressure as will the vertical conduit 30. This serves 'to draw the raw material of rather large size down through conduit 38 and prevents it from clogging smaller discharge passage 33.

The final particle size in a run employing tungsten carbide cobalt comprising percent cobalt and 90 percent tungsten carbide having a density of 14.50 grams per cubic centimeter, a hardness of 86.5-88.0 Rockwell A scale and a transverse rupture strength of 300,000 p.s.i. would be on the average of less than 2 microns ranging from 1 micron to microns.

A typical test run employing such a tungsten carbide cobalt material is set forth in the table below.

688 pounds of raw material having an initial mesh size range from 8 to were introduced into the appara- The foregoing description is merely intended to illustrate an embodiment of the invention. The component parts have been shown and described. They each may have substitutes which may perform a substantially similar function; such substitutes may be known as proper substitutes for the said components and may have actually been known or invented before the present invention; these substitutes are contemplated as being within the scope of the appended claims, although they are not specifically catalogued herein.

We claim:

1. Apparatus for pneumatically pulverizing material comprisin (a) a closed vessel defining a blast chamber, the interior surface of the blast chamber being fabricated of the material being pulverized therein,

(b) a blast nozzle extending into the blast chamber connected to a source of high pressure, air,

(0) the blast nozzle having an internal passage and an external surface in the blast chamber fabricated of the material being pulverized and passing there through,

(d) an impact shield in the blast chamber opposite the end of the nozzle, the surface of the impact shield opposite the nozzle being fabricated of material being pulverized thereagainst,

(e) means for introducing material to be pulverized into the nozzle and (f) classifier means connected between the bottom of the blast chamber and the nozzle adapted to separate oversized particles of material from undersized particles, passing the oversized particles to the nozzle and the undersized particles to collection means.

2. Apparatus for pneumatically pulverizing material comprising:

(a) the structure in accordance with claim 1 and (b) a material feed hopper on the vessel defining the blast chamber,

(0) a feed passage extending between the bottom of the feed hopper and the blast chamber,

(d) a material cycling conduit connected between the bottom of the blast chamber and the classifier means, and

(e) a generally vertical feed conduit connected between the blast chamber from a position in the proximity of and beneath the feed passage and the material cycling conduit.

3. Apparatus for pneumatically pulverizing material comprising:

(a) a closed vessel defining a blast chamber;

(b) a blast nozzle extending into the blast chamber;

(c) an impact shield in the blast chamber opposite the end of the nozzle;

(d) a material cycling conduit connected to the bottom of the blast chamber;

(e) vacuum generating classifier means connected to the material cycling conduit and located above the blast chamber, the classifier means having an oversized particle discharge port in its bottom and an undersized particle discharge port;

(f) a vacuum hopper connected to the oversized particle discharge port, the vacuum hopper normally being under negative pressure, generated by the classifier means;

(g) a feed hopper connected to the vacuum hopper and located therebeneath;

(h) first valve means between the vacuum hopper and the feed hopper;

(i) a T conduit connected to the bottom of the feed hopper;

(j) a source of high pressure air and the blast nozzle connected to the T conduit;

(k) second valve means between the feed hopper and the T conduit;

(l) means for operating the first and second valve means in timed relationship to each other, and

(m) means for introducing material to be pulverized into the nozzle.

4. Apparatus for pneumatically pulverizing material comprising:

(a) the structure in accordance with claim 3, and

(b) pressure diiferential detection means connected between the material recycling conduit and the blast nozzle, and operatively connected to and controlling the second valve means between the T conduit and the feed hopper, the second valve means opening when no material is passing through the nozzle.

5. Apparatus for pneumatically pulverizing material comprising:

(a) the structure in accordance with claim 3, and

(b) a material feed hopper on the said closed vessel defining the blast chamber;

(0) a feed passage connecting the material feed hopper and the blast chamber;

(d) a generally vertical feed conduit connecting the blast chamber with the material recycling conduit extending from the blast chamber from a position in the proximity of and beneath the said feed passage.

6. Apparatus for pneumatically pulverizing material comprising:

(a) the structure in accordance with claim 3, and

(b) the interior surface of the blast chamber, the internal passage in the nozzle, the external surface of the nozzle in the blast chamber, and the surface of the impact shield opposite the nozzle fabricated of the material being pulverized.

7. Apparatus for pneumatically pulverizing material comprising:

(a) a closed vessel defining a blast chamber;

(b) a blast nozzle extending into the blast chamber connected to a source of high pressure air;

(c) the blast nozzle having an internal passage fabricated of the material being pulverized and passing therethrough;

(d) an impact shield in the blast chamber opposite the 7 References Cited by the Examiner end 0? th nozzle, surface Of the P opposite the nozzle being fabricated of material belng v V pulverized thereagainst; 7 253,344 2/82 chlche'ster 241-40 (e) means for introducing material to be pulverized 5 1347-009 2/32 KPHbOhm 2414O into the nozzle, and 2,392,019 1/46 W1egand 241-40 X (f) classifier means connected between the bottom of 11/53 f i 3,058,673 10/62 Firing 241-39 the blast chamber and the nozzle adapted to separate oversized particles of material from undersized particles, passing the oversized particles to the nozzle 1() ANDREW JUHASZ Pnmary Exammer' and the undersized particles to collection means. I. SlENCER OVERHOLSER, Examiner.

Claims (1)

1. APPARATUS FOR PNEUMATICALLY PULVERIZING MATERIAL COMPRISING: (A) A CLOSED VESSEL DEFINING A BLAST CHAMBER, THE INTERIOR SURFACE OF THE BLAST CHAMBER BEING FABRICATED OF THE MATERIAL BEING PULVERIZED THEREIN, (B) A BLAST NOZZLE EXTENDING INTO THE BLAST CHAMBER CONNECTED TO A SOURCE OF HIGH PRESSURE, AIR, (C) THE BLAST NOZZLE HAVING AN INTERNAL PASSAGE AND AN EXTERNAL SURFACE IN THE BLAST CHAMBER FABRICATED OF THE MATERIAL BEING PULVERIZED AND PASSING THERETHROUGH,

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