US 2339568 A
Description (OCR text may contain errors)
Jan. 18, 1944. A. c. HOBBlE 2,339,563
GRINDING AND CLASSIFYING APPARATUS I Filed April 16, 1941 WBRATOR INVENTOR ANS/527C #05565 Patented Jan. 18, 1944 GRINDING AND CLASSIFYINQ APPARATUS Albert C. Hobbie, Moorestown, N. 1., assignor to International Pulverizing Corporation, Moorestown, N. J a corporation of New Jersey 7 Application April 16, 1941, Serial N0. 388,872
This invention relates to unitary fluid vortex grinding andclassifying apparatus for the provision of materials in a finely divided form and is more particularly concerned with an improvement in means wherein. finely-divided particles are separated from the driving fluid and collected.
The present invention is primaril directed to an improvement in the apparatus described in United States Letters Patent 2,032,827. The apparatus described in said patent comprises a gaseous vortex chamber, means to supply material to be ground to said chamber, and means in which gas and entrained fine particles from said vortex. chamber are separated, the gas discharged, and the fine particles collected. As
shown in said patent, the vortex is created by a gas injected under a relatively high pressure into a circular planar zone, from various points on the periphery of said zone, tangential to a theoretical circle within said zone. This produces an inwardly spiralling gaseous vortex in said zone or chamber upon which is superimposed the jet action of the said high velocity Jets of gas introduced around the circular confining wall of the vortex zone. As further shown in said patent, materials to be ground may be introduced directly into the vortex chamber, preferably near its periphery, through the top thereof by an injector type feeder. In carrying out the process described in said patent, certain materials have evidenced a tendency to build up on 'the bottom of the vortex chamber and to bridge in the separating and collecting zone. As a result of particle accretion on the confining walls of the separating zone and the bottom of the vortex chamber, the efliciency of the grinding and classifying action of the apparatus was reduced. Various types of rapping and vibrating methods were applied to the separating zone with little or no success, dueto the localized vibration resulting from their use.
It is accordingly an object of the present invention to provide an improvement in the means for separating the gas and fine particles whereiii by efiicient collection of the particles is obtained.
A further object of the invention is the eliminaa larly pointed out in the claims, and illustrated in the annexed diagrammatic drawing; the following description setting forth in detail certain means for carrying out the invention by way of illustration and constitute but several of the various ways in which the principle of the invention may be used.
In said annexed drawing:
The singl figure is a diagrammatic sectional elevation of one form of apparatus embodying the invention. I
It has been established that fracturable material can be subdivided readily by introducing such materials crushed to suitable fineness, e. g., 40 to 10 mesh, into a gaseous, inwardly spiralling, vortex created within a generally circular planar axially-confined vortex chamber. The driving fluid is supplied continuously through a plurality of jets in the circular confining wall of the chamber to maintain the vortex and the fluid carrying fine particles of the solid, e. g., 1 to 10 microns in size, is led from the vortex zone through a restricted opening into a co-axial gassolid separating zone. In this separating zone the vortical motion of'the gas stream continues and is utilized to throw out the solid, the gas being discharged through a tube co-axial with said zones and solid particles collecting in the bottom of the separating zone.
In my improvement in such apparatus, the hollow cylindrical collection chamber is Joined, preferably integrally as by welding, to'the annular floor of the vortex chamber to form a gastight joint. The'annular floor 4 of the circular vortex zone is held between the Peripheral wall 2 of said zone I and an annular supporting memher 8, a narrow spacing ring I being used to prevent contact between the fioor 4 and the annular supporting member 8. This arrangement permits the fioor 4 of the vortex zone to fiex and function as a diaphragm, since it is fixed at its periphery relative to the confining wall 2 of the vortex chamber I. The other end of the collection chamber is mounted in a manner adapted to permit axial movement of the chamber and may be mounted to permit slight lateral move ment. Suitable means, such as a vibrator, are employed to impart a reciprocating axial movement to said collection chamber which also causes the fiexure of the floor of the vortex zone.
Referring now to the drawing, the circular vortex chamber i is defined by a peripheral wall 2, a top plate 3, and an annular fioor or bottom plate 4. The peripheral wall 2 is pierced by a plurality of nozzles 5 to admit a gas under pressure from a header 6. At the periphery of the bottom plate 4 is a spacing ring I resting upon an annular supporting member I which carries, at least in part, the vortex chamber I.
From this annular supporting member I depend a plurality of vertical rods 9 which in turn carry an annular supporting member III for the pipe leading to a rotary discharge gate (not shown) and the lower end of the collection chamber II. The circular wall I! of the collection chamber I2 is fixed to the inner edge of the bottom plate 4. At its lower end, the wall IQ of the collection chamber I2 is secured to the inner edge of annular plate H which is mounted at its periphery between resilient rings l5 and it. These rings l5 and ii are securely held in position by bolts l1 extending through the supporting member l0 and an annular retaining member It. A suitable vibrator I9 is mounted upon the wall it of the collection chamber II to impart a substantially axial motion to the said wall and to cause flexing 01' the bottom plate 4 of the vortex chamber l. The entire mill assembly may be carried as on supporting brackets 2 i Solid particles fed into the vortex chamber I through an injector tube 22 are subdivided by the action of the fluid jets and the swirling gas stream carrying fine particles spirals inwardly toward the center of the vortex chamber. The spiralling gas stream moves down the wall I: of the collection chamber I 2 and vents upwardly through the center of the collector out through a co-axial tube 20.
In a mill of conventional construction, employing a bottom plate which is not free to move as a diaphragm and in which the lower end 'of the collection chamber is fixedly mounted, considerable trouble has been experienced in grinding materials such as titanium pigments and other materials having similar accretion characteristics. With the construction illustrated and described, it has been possible to operate the apparatus over -periods of time exceeding a month whereas with and of the collector well be sufficient to support the internal pressure of the gas without deformation. In operating a mill with a vortex chamber thirty inches in diameter I have found that the bottom plate diaphragm and collector may be constructed of one-eighth inch mild steel plate. The resilient rings supporting the lower end of assesses the collector may be of rubber or other plastic, being chosen to withstand the temperature of the gaseous grinding medium.
While I have described a specific construction, it will be apparent from that construction that other means of securing the lower end of the collector barrel may be utilized, and that the construction may be modified in any desired man ner as long as the collector is free to move vertically and somewhat sideways and the bottom plate is fixed only at its periphery. The annular supporting member for the bottom of the collector barrel may be of such size that it can be fixedly mounted at its periphery and still, by flexing action, permit vertical movement of the collector.
. I claim:
1. In a unitary grinding and classifying apparatus, the combination of a generally circular, planar chamber axially confined by a top plate and an annular flexible bottom plate and havlnl jet openings in the circular confining wall of said chamber through whicha gas under pressure can be supplied to create a gaseous inwardly spiralling vortex in said chamber which discharges therefrom through the opening in said annular bottom plate; means to supply material to be ground to said chamber; a hollow, generally cylindrical, collector fixed to said annular bottom plate near the inner concentric circle thereof and co-axial with said chamber; a mounting for the other end of said collector adapted to permit axial movement thereof; means to impart a reciprocating axial movement to said collector; and a gas discharge tube co-axial with said vortex chamber and said collector and extending through the top plate of said chamber.
2. In a unitary grinding and classifying apparatus, the combination of: a generally circular, planar chamber axially confined by a top plate and an annular flexible bottom plate and having jet openings in the circular confining wall of said chamber through which a gas under pressure can be supplied to create a gaseous inwardly spiralling vortex in said chamber which discharges therefrom through the opening in said annular bottom plate; means to supply material to be ground to said chamber; a hollow, generally cylindrical, collector fixed to said annular bottom plate near the inner concentric circle thereof and co-axial with said chamber; a mounting for the other end of said collector adapted to permit axial movement thereof a vibrator for imparting a reciprocating axial movement to said collector; and a gas discharge tube co-axial with said vortex chamber and said collector and extending through the top plate of said chamber.
ALBERT C. HOBBIE.