EP1618959A1

EP1618959A1 - Pressurized air counter-jet micronizing mill

Info

Publication number: EP1618959A1
Application number: EP05013325A
Authority: EP
Inventors: Francesco Marcon
Original assignee: Stm Di Marcon Francesco & C Sas
Current assignee: Stm Di Marcon Francesco & C Sas
Priority date: 2004-07-23
Filing date: 2005-06-21
Publication date: 2006-01-25
Also published as: ITMI20041504A1

Abstract

A pressurized air counter-jet micronizing mill comprises a loading system which directs the inlet product of the disgregating and selecting body at first to a peg disgregating unit and then to a rotary blade basket selector.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a pressurized air micronizing device.
As is known, pressurized air micronizer devices are conventionally used to reduce to a very fine particle size a lot of chemical and mineral substances.
In particular, in the chemical and pharmaceutical field it is frequently required to provide product particles having a particle size with an average diameter which for a 98% rate is less than 2 microns.
The milling of the product is made by causing pressurized air concentric jets to impinge against the material to be micronized, by exploiting the friction force generated between the product particles.
Owing to the provision of a disgregating device, supplying the grinding mill, it is possible, as a novelty with respect to prior embodiments, supply the apparatus with product to be ground having a particle size larger than those up to now used.
By way of an example, in prior micronizing methods, for providing particulated substances including particles having an average diameter in a rate of 98% less than 2 microns, it was necessary to supply products having a particle size equal to or less than 300 microns.
Actually, by this novel device, owing to a combined disgregating operation and first selecting operation performed in the top portion of the apparatus, immediately after the inlet of the product to be micronized, it is possible to withdraw from the product mass particles with an already fine particle size, thereby preventing them from entering the milling chamber, thereby allowing to reduce the micronizing time and power required by the compressor to produce pressurized air, so as to greatly increase the production yield.
In prior conventional devices, all the product to be ground is conveyed by gravity falling into the grinding chamber arranged at the bottom of the apparatus, where are provided on a same plane the micronizing nozzles causing the pressurized air flows to converge to a single central point of the chamber.
The product particles are caused to impinge one against the other thereby mutually disgregating and breaking.
The air amount introduced by the nozzles, which has exhausted its grinding kinetic force, is conveyed, by suction, to the top portion of the apparatus (the selection chamber).
During this operating step, the product parts of lighter weight, and according of finer particle size, are entrained and subjected to the selector basket action, which allows only desired size particles to pass therethrough.
The latter particles, also by suction, are conveyed to a process sleeve filter, where they are separated from air.

SUMMARY OF THE INVENTION

Accordingly, the aim of the present invention is to provide a pressurized air micronizing device which is improved with respect to the prior art.
Within the scope of the above mentioned aim, a main object of the present invention is to provide improvements in the automatic recirculation of the product inside the device, to provide a set or desired particle size, which allows to operate in a target working range, without any limitations, owing to the flexible operation of the mill adapted to micronize materials in two different embodiments: with automatically adjusted swinging nozzles and with manually adjusted directable nozzles.
The above mentioned aim and objects, as well as yet other objects, will become more apparent hereinafter, are achieved by a pressurized air micronizing device comprising:

a loading system;
a disgregation and selection chamber in which are performed a disgregating and first selecting as determined by a removal of already fine particles from the inlet product mass and a definitive selection of said particle during a post-milling step;
a grinding chamber with directable and swinging micronizing nozzles, adapted to automatically improve the product recirculation, either with or without an auxiliary fluidification nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more apparent hereinafter from the following disclosure of a preferred, though not exclusive, embodiment of the invention which is illustrated, by way of an indicative, but not limitative, example, in the accompanying drawings, where:

Figure 1 is a cross sectional elevation view of the pressurized air micronizing device, in its swinging nozzle embodiment, according to the present invention;
Figure 2 is a further longitudinal cross-section elevation view of the pressurized air micronizing device in an orientable nozzle embodiment thereof according to the present invention;
Figure 3 is a detail view, in elevation, and longitudinal cross section, of the nozzle of the pressurized air micronizing device, in the swinging nozzle embodiment thereof, according to the present invention;
Figure 4 is a further longitudinal cross sectional elevation detail view of the nozzle with a fluidification device, associated with the pressurized air micronizing device, in an orientable nozzle embodiment, according to the present invention;
Figure 5 is a further longitudinal cross section elevation view of the disgregating and selecting assembly of the pressurized air micronizing device, in an orientable nozzle and swinging nozzle embodiment thereof, according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the number references of figures 1, 3 and 5, the pressurized air micronizing device, in a swinging nozzle embodiment thereof, according to the present invention, as generally indicated by the reference number 1, comprises two different loading systems which can be alternately used depending on the characteristics of the product or material to be micronized.
More specifically, the loading system, including a rotary valve 2, associated to a conveyer 3, directs the product fed to the disgregating and selecting body 4, at first to the peg disgregating device 5 and then to the rotary blade selecting basket 6.
The selected already fine product, by a suction effect, will be directed along the longitudinal conveyor 7 to the process sleeve filter.
The material which is still in a coarse condition and which cannot be selected, will fall, under the gravity force, into the grinding chamber 8, and will be deposited on the chamber bottom 9.
Then, said material is crushed and ground because of the impacts of the product particles which are accelerated by the pressurized air flow projected with a high speed by the swinging nozzles 10, which are mutually opposite and arranged on the same plane.
The swinging or oscillating motion of said nozzles along the vertical planes of the chamber 8 is controlled by an automatic device 11 and allows to take the product parts deposited on the bottom 9.
Said product parts, in particular, are upward projected to a position suitable for grinding.
The raising air and material flow is facilitated by a specifically designed configuration of the bottom 9, which is convex toward the inside of the chamber 8 and which allows a pressurized air flow having a raising or upward directed component to be generated.
The product, brought to a fine particle size because of the suction effect, will be directed in the selecting body 4 to the rotary blade basket selector 6, which will sieve or select said product based on a target or desired particle size.
Then, also under a suction effect, the selected material or product will be directed along the longitudinal conveyor 7 toward the process sleeve filter.
The loading system with a double wing of "clapet" valve 12 allows the product to be directly introduced into the milling chamber 8, where is performed the same grinding and crushing process as that thereinabove disclosed.
With reference to the number references of figures 2, 4 and 5, the pressurized air micronizing device, in an orientable nozzle embodiment thereof, and as generally indicated by the reference number 1, comprises two different loading systems, which can be alternately used, depending on the characteristics of the product to be micronized.
In particular, the rotary valve loading system 2, associated with a conveyor 3, directs the product fed to the disgregating and selecting body 4, at first to a peg disgregator 5 and then to a rotary blade basket selector 6.
The already fine selected or sieved product, will be then directed, by a suction effect, along the longitudinal conveyor 7 toward the process sleeve filter.
The material still in a coarse condition, which cannot be selected or sieved, will fall, under its gravity, into the grinding chamber 8, thereby depositing on the bottom 13 of said grinding chamber.
Then, a crushing and grinding is performed by causing the product particles to impact against to one another, said product particles being accelerated by the pressurized air flow projected with a high speed from the orientable nozzles 14 which are opposite to one another and arranged on the same plane.
The orienting of the above mentioned nozzles along the vertical plane of the grinding chamber 8 is controlled by a manual adjusting device 15, allowing said nozzle to be located with an optimum inclination suitable for grinding.
The product of material parts, deposited on the conic bottom 13, are taken by a fluidification nozzle 16, which projects upward the product particles, to a position suitable for grinding.
The fine product will be directed, by suction, through the selecting body 4 to the rotary blade basket selector 6, to be selected or sieved to the target particle size.
Then, also by suction, the selected or sieved material will be directed along the longitudinal conveyor 7 to the process sleeve filter.
The loading system-double wing or clapet valve 12 assembly will allows the product to be directly fed to the grinding chamber 8, whereas is performed the same grinding and crushing process as that hereinabove disclosed.
It has been found that the invention fully achieves the intended aim and objects.
In fact, the invention provides a pressurized air micronizing device, in which is performed an automatic recirculation of the product, up to provide a target particle size, with a consequent great reduction of the necessary material and power.
In practicing the invention, the used materials, as well as the contingent size and shapes, can be any, depending on requirements and the status of the art.

Claims

A pressurized air counter-jet micronizing mill, characterized in that said mill comprises a loading system directing a product fed to a disgregating and selecting body (4) at first to a peg disgregator (5) and then to a rotary blade basket selector (6).
A pressurized air counter-jet micronizing mill, according to claim 1, characterized in that in said mill the selected already fine product is directed, by an air suction effect, along a longitudinal conveyor (7) toward a process sleeve filter.
A micronizing mill, according to the preceding claims, characterized in that the material remaining still coarse and not selectable, is caused to fall, under the gravity force, into a grinding chamber (8), so as to be deposited on a bottom (9) of said grinding chamber.
A micronizing mill, according to one or more of the preceding claims, characterized in that said micronizing mill comprises a loading system with a rotary valve (2) associated to a conveyor (3) directing the product fed to the disgregating and selecting body (4) at first to a peg disgregator (5) and then to a rotary blade basket selector (6).
A micronizing mill, according to one or more of the preceding claims, characterized in that the material falling into said grinding chamber (8) and depositing on the bottom (9) of said grinding chamber, is subjected to a crushing and grinding process, by causing the product particles to be impacted one against the other, said product particles being accelerated by the pressurized air flow projected with a high speed by oscillating nozzles (10) which are arranged opposite to one another and on a same plane.
A micronizing mill, according to one or more of the preceding claims, characterized in that said oscillating nozzles driven along the vertical plane of said grinding chamber (8) are controlled by an automatic control device (11) allowing to remove product parts deposited on said bottom (9) of said grinding chamber (8).
A micronizing mill, according to one or more of the preceding claims, characterized in that said parts of said product deposited on said bottom (9) are upward projected to a position suitable for grinding by an upward directed air flow, which is facilitated by the configuration of said bottom (9) which is convex toward the inside of the grinding chamber (8) and allows to provide a pressurized air flow having an upward directed component.
A micronizing mill, according to one or more of the preceding claims, characterized in that in said micronizing mill, said product, brought to a fine particle size by a suction effect, is directed in said selecting body (4) to said rotary blade basket selector (6) to be particle size selected to a target particle size.
A micronizing mill, according to one or more of the preceding claims, characterized in that said micronizing mill alternately comprises a loading system with a double wing or clapet calve (12) allowing said product to be directly fed to said grinding chamber (8) to be ground and crushed therein.
A micronizing mill, according to one or more of the preceding claims, characterized in that, by using said loading system including said rotary valve (2), associated to said conveyor (3), the selected already fine product is directed, by suction, along said longitudinal conveyor (7) toward said process sleeve filter, whereas the material in a still coarse particle size condition and not selectable falls, under the gravity force, into said grinding chamber (8) and deposits on the bottom (13) of said grinding chamber.
A micronizing mill, according to one or more of the preceding claims, characterized in that in said micronizing mill the product is crushed and ground by impacts of said product particles, said product particles being accelerated by said pressurized air flow and projected with a high speed by said orientable nozzles (14), said nozzle being opposite to one another and arrange on a same plane.
A micronizing mill, according to one or more of the preceding claims, characterized in that the orientation of said nozzles along the vertical planes of said grinding chamber (8) is controlled by a manual adjusting device (16) allowing said nozzles to be arranged with an optimum inclination suitable for grinding.
A micronizing mill, according to one or more of the preceding claims, characterized in that said product particles deposited on said bottom (13) of said grinding chamber (8) are removed by a fluidification nozzle (16) adapted to project upward said product particles to a position suitable for grinding them.
A micronizing mill, according to one or more of the preceding claims, characterized in that in said micronizing mill, said product, brought to a fine particle size, is directed, by suction, and conveyed toward the selecting body (4) to said rotary blade basket selector (6) to be selected according to a target particle size.
A pressurized air counter-jet micronizing mill, according to one or more of the preceding claims, characterized in that said micronizing mill comprises a plurality of constructional elements as broadly disclosed and illustrated in the preceding disclosure and in the drawings accompanying the subject Industrial Invention Patent Application.