US3429512A - Sonic method and apparatus for grinding rock material and the like to powder - Google Patents

Description

Feb. 25, 1969 G BODlNE, JR 3,429,512

SONIC METHOD AND APPARATUS FOR GRINDING ROCK MATERIAL AND THE LIKE TO POWDER Filed Oct. 20, 1965 Sheet Of 3 Ma /V702. fiLBEQT 6. Boo/Me, TR.

5) TILE-E J70 Cfiwc? F 25, 1969 A. G. BODINE, JR 3,429,512

SONIC METHOD AND APPARATUS FOR GRINDING ROCK MATERIAL AND THE LIKE TO POWDER Sheet Filed Oct. 20, 1966 Feb. 25, 1969 E mNE, JR 3,429,512

SONIC METHOD AND APPARATUS FOR GRINDING ROCK I MATERIAL AND THE LIKE TO POWDER Filed Oct. 20. 1966 Sheet :EEI:

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United States Patent SONIC METHOD AND APPARATUS FOR GRIND- ILJG ROCK MATERIAL AND THE LIKE TO POWDER Albert G. Bodine, Jr., 7877 Woodley Ave., Van Nuys, Calif. 91406 Filed Oct. 20, 1966, Ser. No. 588,030

US. Cl. 24124 Int. Cl. B02c 17/04, 17/14; 1507b 3/10 12 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a sonic method and apparatus for grinding rock material and the like to powder, and more particularly to such a method and apparatus in which sonic energy is utilized to pulverize rock-like material to a preselected fine particle size in a continuous feedthrough-type process.

Techniques of the prior art for pulverizing rock material to a powdery form in such operations as the manufacture of cement, the processing of ores and the grinding of chemical base stock, generally involve the use of a rotating barrel having loose balls or rods therein which, with the rotation of the barrel, pound against the material to achieve the crushing action. This technique has several shortcomings. Firstly, it is inherently inefficient by virtue of the fact that the material must be processed in a batch, thus requiring a relatively large drum and the use of considerable power to rotate such drum if any quantity of material is to be processed at a time. This prior art process is also relatively time consuming in view of its batch-type operation, which requires that all of the material must be kept in the drum until an entire batch has been crushed to the desired fineness. A good deal of waste of energy occurs, not only by virtue of the fact that totally processed material is worked on along with the unworked material in any batch, but also because the fully pulverized material often acts as an insulator for the remaining chunks making their pulverization more diflicult. Further, the loose balls and rods used in this type of crushing operation cause heavy wear on the drum lining, necessitating frequent repair and/or replacement thereof.

The method and apparatus of this invention eliminate many of the shortcomings of prior art crushing devices by efficiently utilizing sonic energy to pulverize rock material in a continuous feedthrough process. The use of sonic energy in the device of the invention enables highly effective pulverizing action in a much shorter period of time than heretofore possible. Means are provided in the device of the invention to remove material as soon as it is ground to the desired particle size so that energy is not wasted on material that has been properly pulverized and such material does not insulate material yet to be ground, from the pulverizing force. Further, Wear on the processing equipment is much less than with prior art ball and rod mills.

The apparatus of the invention utilizes a container member into which the material to be crushed is con- 3,429,512 Patented Feb. 25, 1969 tinually fed. This container member is sonically excited as part of a resonant vibration system. Biased against the material to be ground is an inertial grinder member, the cyclic energy generated in the resonant system causing heavy impact at the interfaces between the material to be ground and the container and grinder members. The ground particles are selectively removed as they are ground to the desired particle size, leaving only the portions requiring additional grinding in the container. In one embodiment of the device of the invention, the container is in the form of a crucible with the grinder member being in the form of a relatively large ball member, pneumatic means being utilized to remove particles as they are ground to the desired size. In other embodiments of the device of the invention, the container is in the form of a trough member, with the inertial grinder in the form of a bar member which is biased against the material to be crushed either by the force of gravity or a biasing member, such material being held in the trough member and moved therealong by gravity as the pulverizing action proceeds until it finally is deposited in a receptacle when it reaches the desired particle size.

It is therefore an object of this invention to provide a more efiicient method and apparatus for crushing rock material to powder by means of sonic energy.

It is a further object of this invention to provide a more rapid technique for pulverizing rock material.

It is still another object of this invention to provide a continuous feedthrough method and apparatus for pulverizing rock material in which the material is automatically removed from the processing apparatus as soon as it reaches the desired particle size.

It is still a further object of this invention to provide a more economical technique for pulverizing rock material.

It is another object of this invention to provide a method and apparatus for pulverizing rock material in which the wear and tear on the processing apparatus is considerably less than in prior art devices.

Other objects of this invention will become apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is an elevational view of a first embodiment of the device of the invention;

FIG. 2 is a view taken along the plane indicated by 22 in FIG. 1',

FIG. 3 is a cross-sectional view taken along the plane indicated by 3-3 in FIG. 2;

FIG. 4 is a view taken along the plane indicated by 4-4 in FIG. 1;

FIG. 5 is a cross-sectional view in elevation of an oscillator unit which may be utilized in the device of the invention;

FIG. 6 is a cross-sectional view in elevation of a second embodiment of the device of the invention;

FIG. 7 is a cross-sectional view taken along the plane indicated by 77 in FIG. 6;

FIG. 8 is a cross-sectional side view in elevation of a third embodiment of the device of the invention utilizing a biasing member in the form of a spring; and

FIG. 9 is an end elevational view of the embodiment of FIG. 8.

It has been found most helpful in analyzing the operation of the device of this invention to analize the acoustically vibrating circuit involved to an equivalent electrical circuit. This sort of approach to analysis is well known to those skilled in the art and is described, for example, in chapter 2 of Sonics by Heuter and Bolt, published in 1955 by John Wiley and Sons. In making such an analogy, force F is equated with electrical voltage E, velocity of vibration u is equated with electrical current i,

mechanical compliance C 1s equated with electrical capacitance (3,, mass M is equated with electrical inductance L, mechanical resistance (friction) R is equated with electrical resistance R, and mechanical impedance Z is equated with electrical impedance Z Thus, it can be shown that if a member is elastically vibrated by means of an acoustical sinusoidal force, F sin wt (w being equal to 211" times the frequency of vibration),

Wh:re wM is equal to l/wC a resonant condition exists, and the effective mechanical impedance Z is equal to the mechanical resistance R the reactive impedance components wM and l/wC cancelling each other out. Under such a resonant condition, velocity of vibration u is at a maximum, power factor is unity, and energy is most elficiently delivered to a load to which the resonant system may be coupled.

It is to be noted that in the device of this invention the mass and compliance for forming the resonantly vibrating system are furnished by the structural members of such system themselves so that the rock material and the inertial grinder member are not incorporated as reactances in such system. The rock material under such conditions acts as a resistive impedance load which provided no significant reactive components, while the grinder member is coupled to the rock material as a high-mass load which remains substantially inert. This employment of apparatus resonance results in a random vibration of the rock particles, rather than a lumped coherent vibration such as results from nonresonant vibrating apparatus, with a considerable relative motion occurring between the separate particles. It is believed that each of the individual irregular particles When energized by the sonic energy in this sonic resonant fashion separately vibrates in a random path with a relatively fixed radius of vibration which changes in direction but remains fixed in magnitude. Such random vibration effectively separates the particles so that they do not adhere to each other. The net result is a uniquely high degree of fluidization of such particles which effectively aids in the separation of the fully ground material from that requiring additional grinding.

It is also important to note the significance of the attainment of high acoustical Q in the resonant system being driven, to increase the efliciency of the vibration thereof and to provide a maximum amount of energy for the grinding operation. As for an equivalent electrical circuit, the Q of an acoustically vibrating circuit is defined as the sharpness of resonance thereof and is indicative of the ratio of the energy stored in each vibration cycle to the energy used in each such cycle. Q is mathematically equated to the ratio between wM and wR Thus, the effective Q of the vibrating circuit can be maximized to make for highly efficient, high-amplitude vibration by minimizing the elfect of friction in the circuit and/ or maximizing the etfect of mass in such circuit.

Of significance in the implementation of the method and devices of this invention, is the high acceleration of the components of the elastic resonant system that can be achieved at sonic frequencies. The acceleration of a vibrating mass is a function of the square of the frequency of the drive signal times the amplitude of vibration. This can be shown as follows:

The instantaneous displacement y of a sinusoidally vibrating mass can be represented by the following equation:

where Y is the maximum displacement in the vibration cycle and w is equal to 211-1, f being the frequency of vibration.

The acceleration a of the mass can be obtained by differentiating Equation 2 twice, as follows:

y=Y cos wt The aceleration a of the mass can be obtained by diffen At resonance, Y is at a maximum and thus even at moderately high sonic frequencies, very high accelerations are achieved making for correspondingly high vibrational forces at the grinding interfaces.

In considering the significance of the parameters described in connection with Equation 1, it should be kept in mind that the total elfctive resistance, mass, and compliance in the acoustically vibrating circuit are represented in the equation and that these parameters may be distributed throughout the system rather than being lumped in any one component or portion thereof.

It is also to be noted that an orbiting-mass oscillator may be utilized in the device of the invention that automatically adjusts its output frequency to maintain resonance with changes in the characteristics of the load. Thus, in the face of changes in the effective mass and compliance presented by the load, the system automatically is maintained in optimum resonant operation by virtue of the lock-in characteristics of applicants unique orbitingmass oscillator. The virbrational output from such an orbiting-mass oscilator is generated along a controlled predetermined coherent path to provide maximum output along a desired axis or axes. The orbiting-mass oscillator automatically changes not only its frequency but its phase angle and therefore its power factor with changes in the resistive impedance load to assure optimum efliciency of operation at all times.

Referring now to FIGS. 1-4, a first embodiment of the device of the invention is illustrated. Container member 11 is in the general form of a crucible and is supported on pedestal 12. Pedestal 12 in turn is supported on bracket member 14 which is attached to bar member 17 by means of pin 16. Container member 11, pedestal member 12, bracket 14 and bar member 17 are all preferably fabricated of a metal such as steel, bar member 17 having a relatively high mass. Bar member 17 is supported on pillars 19 and 20 by means of U-shaped brackets 21 and 22, respectively, which are attached to the bar by means of associated pins 23 and 24. Vibrational isolation is provided between pillars 19 and 20 and brackets 21 and 22, respectively, by means of isolator members 25 and 26, which may be of rubber or a comparable material.

Attached to the bottom of bracket member 14, as for example by welding, is housing 31 of orbiting-mass oscillator 30. Housing 31 has races 32 and 33 formed therein. Races 32 and 33 have rotors 34 and 35, respectively, contained therein which are rotatably driven thereabout at the same speed but in opposite directions, as indicated by arrows 37. Rotors 34 and 35 are phased with respect to each other so that transverse vibrational forces cancel each other out while forces in the directions indicated by arrows are additive.

Rotors 34 and 35 are driven by means of motor 44, the drive shaft of which is coupled to the rotors through gear train 45, the input gear a of such gear train being coupled to the motor and gear members 450 and 45d being coupled to the drive shafts of rotors 34 and 35, respectively. Motor 44 is supported on stand 50.

Contained within container member 11 is inertial grinder member 52 which is in the form of a ball having a relatively high mass. Rock material to be crushed is fed into container member 11 through hopper 61. Attached to the walls of container 11 for drawing pulverized material 63 therefrom is aspirator device 65. Aspirator device 65 utilizes a source of compressed air which is fed from tank 66 through pneumatic lines 67 and 68 to flexible lines 69 and 70, respectively. Lines 69 and 70 are connected to the interior of container 11 by means of coupler tubes 71 and 72, respectively, the flexible lines being attached to the coupler tubes by means of clamping bands 74. Vibrational isolation is provided between coupler tubes 71 and 72 and container 11 by means of rubber sleeve members 80 which join the connector tubes to nipple members 81 which threadably engage the container member. Sleeve members 80 are clamped in place by means of clamping bands 82.

Rotors 34 and 35 are rotated at speeds such as to set up resonant vibration of the vibration system including bar member 17 and container member 11, with such resonant vibration being in the directions indicated by arrows 40. With such resonant vibration, a standing wave pattern as indicated by graph lines 90 is set up in bar member 17. High-level vibrational energy is thereby made available at the interfaces between the walls of container 11, the rock material 60 and ball 52. The high-mass ball 52, being separated from crucible 11 by rock material 69, reacts as a substantially inert mass to the vibration forces, with the container by virtue of its high-level sonic vibration cyclically impacting rock material 60 against ball 52. Force for biasing ball 52 against the rock material is provided in this embodiment by means of gravity, but if so desired other biasing means, such as for example a spring member acting against ball 52, may be utilized.

It is to be noted that the impacting force occurs substantially normal to the opposing surfaces of ball member 52 and container 11. This is significant in that, by virtue of such perpendicular action, sliding between the surfaces of the container and ball member is minimized with a resultant minimization of the wear thereof.

It is also to be noted that the rock material 60 being ground within container 11 acts as a resistive load on the resonant vibration system, such system being selfcontained the resonant bar, the container and associated members. This makes for optimum fluidization of the rock material so that the fully ground material tends to more easily be separated from the remaining material by virtue of the aspirating action of aspirator unit 65.

A valve 91 is provided in line 67 to enable the adjustment of the pressure of the air stream. In this manner, the fineness of the particles that will be drawn out of container 11 by the aspirating system can be regulated to achieve the desired particle size in the end product. While an aspiratorunit 65 has been shown for drawing pulverized particles 63 out of container 11, other pneumatic techniques such as a blower discharging into hopper 61 or a vacuum pumping system can be utilized if so desired.

Referring now to FIGS. 6 and 7, a second embodiment of the device of the invention is illustrated. In this second embodiment, components corresponding to those of the first embodiment are given like numerals. Container member 78 is in the form of a trough and additionally performs the function of the bar member of the first embodiment. Container member 78 is supported on base 100 by means of angle iron supports 101 and 102, vibration isolation between the supports and the container being provided by means of rubber pillars 25 and 26. Rock material 60 to be ground is fed into container member 78 through hopper 61 which is supported on bracket 105 attached to base 100. Inertial grinder 79 has the form of a massive bar member which is suspended from the wall of hopper 61 by means of cable 110 and U-shaped hooks 111 and 112, attached to hopper 61 and grinder member 79, respectively. Grinder member 79 is suspended on cable 110 so that a substantial portion of such grinder members longitudinal extent is gravity biased against the rock material 60 sliding down container member 78. Container member 78, in view of its dual functions as both a container and a resonant bar member, has a fairly thick bottom so as to provide a substantial mass and is fabricated of a material having high elasticity such as steel.

Attached to container member 78 is orbiting-mass oscillator 30 which in this case utilizes a single rotor 35, but may otherwise be similar to the oscillator described in connection with the first embodiment. Rotor 35 is rotationally driven by a motor (not shown) at a rotation speed such as to set up resonant vibration in a lateral mode, i.e. in the thickness plane of container 78, such resonant vibration being indicated by wave pattern 116. The resonant vibration system is fully contained within container member 78 and the components attached thereto so that the rock material 60 acts as a resitive load on the vibration system and high-mass grinder member ,79 is substantially inert to the vibrational energy just as for the first embodiment.

The spacing between grinder member 79 and the bottom of container 78 is automatically determined by the largest size particles therebetween, such that grinder member 79 automatically assumes an orientation whereby opposing surfaces of the grinder and container members at the outlet end of the container approach each other closer and closer. Thus, as the material becomes more and more finely ground, the space between the opposing members becomes narrower and narrower so that the finer particles slide down to portions of the trough where they can receive optimum grinding action until they are finally deposited in container 115 when they are fully ground. This movement along the container member is implemented by the fiuidizing action of the sonic energy which also effectively separates the finer material from the coarser material, preventing the aforementioned insulating efiect of such finer particles.

Referring now to FIGS. 8 and 9, a third embodiment of the device of the invention is illustrated. This third embodiment is similar to the second except for the fact that the container member 78 and the grinder member 79 are oriented substantially vertically. In this embodiment, the bias force for urging grinder member 79 against the rock material 60 rather than being provided by virtue of gravity, is furnished by means of spring member 118 which is supported on pillar 119 which projects from bracket 105. Except for this one diiference, the embodiment shown in FIG. 8 is similar in configuration and operation to the embodiment of FIGS. 6 and 7. Container member 78 is supported on bracket 105 by means of support arms 121 and 126 which are vibrationally isolated from the container member by means of isolator mounts 128.

Referring now to FIG. 5, an orbiting-mass oscillator unit which may be utilized in the device of the invention is illustrated. The output gear of gear train 45 rotatably drives shaft 120. Shaft has a socket 122 at the end thereof, which is splined and forms a ball and socket joint with splined ball member 123. Ball member 123 is fixedly attached to shaft 124 which has a crown gear 125 attached to the end thereof. Gear 125 forms a spline joint with splined annular portion 127 of rotor drive member 130. Rotor drive member 130 is rotatably mounted on ball bearings 132. The splined joints between ball member 123 and socket member 122 and rrown gear 125 and splined portion 127 furnish play in the drive system which avoids undue strain on such system with the operation of the oscillator.

The rotor member 137 has a spur gear 137a attached thereto which rides around in a mating ring gear 138a coincident with the race in the oscillator housing 138. The rotor has a pin member 13717 which rides around a pin member 130a protruding from rotor drive member 130, as the rotor is driven by virtue of the engagement of rotor drive gear 137c with rotor drive member gear 13%. Rotor member 137 thus rides around the race formed in its housing.

The technique of this invention thus provides means for efficiently grinding rock material and the like to a powderly form by means of sonic energy. By virtue of the technique of this invention, the finer particles are separated from the coarser ones so that the insulating effect thereof is minimized and such finer particles when they reach a predetermined particle size are automatically removed from the container in which the grinding action is accomplished. Further, the technique of this invention enables continuous feedthrough-type processing, thereby greatly speeding up the processing and enabling more ef fective equipment utilization.

While the technique of this invention has been described and illustrated in detail, it is to be clearly under stood that this is intended by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the following claims.

I claim:

1. A device for pulverizing rock material and the like comprising:

a container member;

means for feeding said material into said container member; an inertial grinder member having a substantial mass, said grinder member being biased against at least part of said material to urge said part of said material against said container member; and

orbiting-mass oscillator means for generating sonic energy, said oscillator means being coupled to said container member to cause high-level sonic vibration thereof,

whereby heavy vibrational impact occurs at the interfaces between the material and grinder and container members to cause the efiicient pulverization of the material.

2. The device as recited in claim 1 wherein said grinder member is biased against said part of material by the force of gravity.

3. The device as recited in claim 1 and including spring means for biasing said grinder member against said part of said material.

4. The device as recited in claim 1 and additionally including means for selectively removing the material from the container when it reaches a predetermined particle size.

5. The device as recited in claim 4 wherein said means for selectively removing the material comprises pneumatic drive means coupled to said container and means for selectively adjusting the pneumatic drive of said drive means.

6. The device as recited in claim 5 wherein said pneumatic drive means comprises aspirator means, said aspirator means including a source of compressed air, a nozzle attached to the walls of said container member, means for providing pneumatic communication between said nozzle and said compressed air source, and means for adjusting the output of said compressed air source to said nozzle to a level necessary to cause the removal of said material when it reaches said predetermined particle size.

7. The device as recited in claim 1 wherein the output frequency of said oscillator is such as to cause resonant vibration of said container member.

8. The device as recited in claim 1 wherein said grinder member comprises a heavy ball, and ball resting freely within said container.

9. The device as recited in claim 1 wherein said grinder member comprises a bar member and said container member is in the form of a sloping trough and .means for positioning said bar member in said trough at an angle with respect to the slope of said trough.

10. The device as recited in claim 1 wherein said orbiting-mass oscillator means comprises a pair of orbitingmass oscillators and means for rotating said oscillators in opposite direction, said oscillators being phased with respect to each other and coupled to said container member to generate vibrations therein solely along a single predetermined axis.

1 1. A method for pulverizing rock material and the like comprising:

feeding said material into a container member;

placing a grinder member against said material, said grinder member having a substantial mass and being biased to urge said material against the walls of said container; and

applying sonic energy to said container member to cause resonant vibration thereof whereby heavy vibrational impact occurs at the interfaces between the material and the container and grinder members to efiectively pulverize said material.

12. The method as recited in claim 11 and additionally including the step of removing said material from the container as soon as it is crushed to a predetermined particle size.

References Cited UNITED STATES PATENTS 1,847,083 3/1932 Flint 241-264 2,856,133 10/1958 Dening et al. 241264 X 3,131,878 5/1964 Bodine 241-262 3,211,388 10/1965 Gartner 241-262 X 3,223,337 12/1965 Snaper 241-262 3,348,781 10/1967 Sackett 241-264 WILLIAM S. LAWSON, Primary'Examiner.

US. Cl. X.R.

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