Title of Invention

MICROFINES PNEUMATIC FINE CLASSIFIER FOR THE CLASSIFICATION OF FINE POWDERS

Abstract

Microfines circular fluid energy mill for producing ultra-fine powders, provided with a pneumatic feeder for continuously feeding the material to be ground to the mill, comprising a vertically oriented disc-shaped chamber provided with a plurality of grinding nozzles for sending compressed air to the grinding zone of the said chamber; two partition members, within the chamber, the outer walls of these partition members being concentric with the inner wall of the disc shaped chamber, the inner walls of the partition members being partly curved to define, therebetween, a disc-centrifuge type pneumatic classifier having an outlet at its centre, for the exit of the fines, the inner walls of the partition members being also partly inclined and linear to allow the lesser fines to slide down into the grinding zone, the said grinding nozzles being aligned with respect to the grinding zone to cause the air jets from these nozzles to enter the said zone tangentially to an imaginary circular path located between and concentric with the irmer wall of the disc shaped chamber and the outer walls of the partition members, said path being more closer to the outer walls of the partition members.

Full Text

This invention relates to microfines circular fluid energy mill for producing ultra-fine powders. Fluid energy mills are known to this art and have been proposed, from time to time, in various forms and constructions. However, the microfines circular fluid energy mill proposed herein is different from the known mills, in that, inter alia, it avoids erosion of the side wall of the grinding chamber; it grinds to better fineness; it has an efficient pneumatic disc-centrifuge type classifier superimposed in the grinding chamber; is efficient in production of high quality ultra-fine powders without any contamination; easy to fabricate, assemble and dissemble for cleaning. Various other features of this invention will be apparent from the description thereof to follow. Microfines circular fluid energy mill for producing ultra-fine powders, according to this invention, is provided with a pneumatic feeder for continuously feeding the material to be ground to the mill, and comprises a vertically oriented disc-shaped chamber provided with a plurality of grinding nozzles for sending compressed air to the grinding zone of the said chamber; two partition members, within the chamber, the outer walls of these partition members being concentric with the inner wall of the disc shaped chamber, the inner walls of the partition members being partly curved to define, therebetween, a disc-centrifiige type pneumatic classifier having an outlet at its center, for the exit of the fines, the inner walls of the partition members being also partly inclined and linear to allow the lesser fines to slide down into the grinding zone, the said grinding nozzles being aligned with respect to the grinding zone to cause the air jets from these nozzles to enter the said zone tangentially to an imaginary circular path located between, and concentric with, the inner wall of the disc shaped chamber and the outer walls of the partition members, said path being closer to the outer walls of the partition members. This invention will now be described with reference to the accompanying drawings, which illustrate, by way of example, one of the possible embodiments of the mill proposed herein. Fig. 1 illustrates the said embodiment, in sectional front view and Fig. 2 illustrates the said embodiment in side view (without the pneumatic feeder, grinding nozzles and auxiliary nozzles). The embodiment is provided with a pneumatic feeder F for continuously feeding the material to be ground into the grinding zone G The embodiment comprises a vertically oriented disc-shaped chamber C provided with a plurality of grinding nozzles N for sending compressed air to the grinding zone G of the said chamber C. Two partition members P are provided within the chamber, the outer walls PO of the partition members being concentric with the inner wall CI of the disc-shaped chamber. The inner walls PI of the partition members are partly curved at PC to define therebetween, a disc-centrifuge type pneumatic classifier chamber CC having an outlet O at the centre, for the exit of fines. The inner walls PI of the partition members are also partly inclined and linear at PL to allow the lesser fines from the classifying chamber to slide down the inclination at PL into the grinding zone G. In the embodiment illustrated, the angle of inclination is 60 degrees to the horizontal. The above arrangement, while resulting in efficient classification of the ground material and consequently, a more efficient grinding operation, effectively demarcates the process of grinding in the grinding zone G and the process of classification in the classification zone in CC thereby fully eliminating the possible interaction between the two processes. The grinding nozzles N are aligned with respect to the grinding zone G to cause the air jets from these nozzles to enter the said zone tangentially to an imaginary circular path, indicated by IC, located between and concentric with, the mner wall CI of the disc shaped grinding chamber and the outer walls PO of the partition members, the said path being closer to the outer walls of the partition members. This orientation enables to avoid the erosion of the inner wall CI of the chamber C and the outer walls PO of the partition members. The pneumatic feeder F feeds the material into the mill at the leading end of the grinding nozzles N, whereby the said material and the air sucked in from atmosphere serve as a virtual screen against any possible erosion of the inner wall CI of the chamber C. This location of the pneumatic feeder also helps in leaving the suction behind the grinding nozzles N in the zone S undisturbed thereby ensuring better classification and recycle. For handling heavier materials and for maintaining the circulation load of such materials in continuous rotation an auxiliary nozzle AN is provided with a nozzle-venturi arrangement so that necessary air can be send into the mill by partially depending on the compressed air. The location of this nozzle is at the lagging end of the grinding nozzles and need to be operated only when it is specifically needed. The terms and expressions in this specification are of description and not of limitation, there being no intention in the use of such terms and expressions of excluding any equivalents of the features illustrated and described; but it is understood that various other embodiments of the mill proposed herem are possible without departing from the scope and ambit of this invention. We Claim 1. Microfines circular fluid energy mill for producing ultra-fine powders, provided with a pneumatic feeder for continuously feeding the material to be ground to the mill, comprising a vertically oriented disc-shaped chamber provided with a plurality of grinding nozzles for sending compressed air to the grinding zone of the said chamber; two partition members, within the chamber, the outer walls of these partition members being concentric with the inner wall of the disc shaped chamber, the inner walls of the partition members being partly curved to define, therebetween, a disc-centrifuge type pneumatic classifier having an outlet at its centre, for the exit of the fines, the inner walls of the partition members being also partly inclined and linear to allow the lesser fines to slide down into the grinding zone, the said grinding nozzles being aligned with respect to the grinding zone to cause the air jets from these nozzles to enter the said zone tangentially to an imaginary circular path located between, and concentric with, the inner wall of the disc shaped chamber and the outer walls of the partition members, said path being more closer to the outer walls of the partition members. 2. Microfines circular fluid energy mill as claimed in Claim 1 wherein the pneumatic feeder feeds the material into the mill at the leading end of the grinding nozzles, whereby the said material and the air sucked in from atmosphere serve as a virtual screen against any possible erosion air material from the feeder serves as a screen against erosion of the inner wall of the disc-shaped chamber and leaves the suction behind the grinding nozzles undisturbed to result in better classification and recycle. 3. Microfines circular fluid energy mill as claimed in Claim 1 or Claim 2 wherein the said nozzles include an auxiliary nozzle with nozzle-venturi arrangement, at the lagging end of the grinding nozzles. 4. Microfines circular fluid energy mill for producing ultra-fine powders substantially as herein described with reference to, and as illustrated in the accompanying drawings.

Documents:

535-mas-98 abstract.pdf

535-mas-98 claims duplicate.pdf

535-mas-98 claims.pdf

535-mas-98 correspondence-others.pdf

535-mas-98 correspondence-po.pdf

535-mas-98 description (complete) duplicate.pdf

535-mas-98 description (complete).pdf

535-mas-98 drawings.pdf

535-mas-98 form-1.pdf

535-mas-98 form-19.pdf

535-mas-98 form-26.pdf