Description:FILED OF THE INVENTION
The invention generally relates to crushing or pulverizing of materials into fine particles. In particular, the invention relates to use of the jet milling system with high-speed air flow for crushing and pulverization of material into fine particles.

BACKGROUND OF THE INVENTION
A jet mill is a system or an apparatus used to reduce the size of particles in various industries. The jet mills are generally reliable because they typically do not include moving parts or screens, blades, shafts or hammers also such jet mills typically do not require the use of any crushing media. The jet mill reduces the size of particles due to high - velocity collisions that occur between the particles injected into a crushing chamber of the jet mill. Jet mills pulverize and comminute crushed material introduced into a crushing chamber by a swirl flow from high speed jets, and are useful in producing pesticides, toners, and other powders having poor heat resistance; ceramic powders; and a variety of other fine powders.
In known jet mills during pulverization of crushed material with a high degree of hardness, problems have arisen, wherein the surface of the internal wall of the crushing or crushing chamber gets scraped away by crushed material contacting the surface of the internal wall of the crushing/crushing chamber. The known way for avoiding this problem has been to slow down the swirl flow in the crushing or crushing chamber. However, slowing down the swirl flow causes problems in so far as the crushing efficiency decreases affecting the obtained product.
In known jet mills, the sole method for increasing the pulverizing efficiency is by increasing the gas spray feed rate. The pressure of the actuating gas is increased in order to increase the gas spray rate. The large-scale compressor equipment that consumes large amounts of electricity is required in order to obtain high-pressure actuating gas.
The prior art jet mills require the complexly shaped mechanical parts be additionally provided inside the crushing chamber, as exemplified by the special mechanisms for adjusting the angle at which the air flow is injected or the mechanism for classification of material or special impact members provided inside the crushing chamber.
Keeping in mind the afore-mentioned problems the inventors of the present invention have come up the jet mill with highly corrosion resistive frame, integrated vortex walls for changing the course of the movement of particles inside the crushing chamber for efficient pulverization capacity with less complex mechanical parts which consumes less electricity and achieves more fine sized particles.

SUMMARY OF THE INVENTION
The present air jet mill equipment for crushing one or more substances comprises a flat circular hollow crushing chamber (20) made of a top surface (10) integrated with a vortex inner walls (55) and a bottom surface (15) integrated with a vortex outer wall (60), a plurality horizontal air nozzles (45) on annular outer wall of the said crushing chamber (20) generating high-speed pressurized air flow through constricted passage, an ancillary chamber (25) in the form of annular classifying zone in attached below the said crushing chamber (20), a feeder (30) for introduction of crushed feed material, a compressed feed gas inlet (35) directing the pressurized feed gas through constricted passage (40) towards the crushed feed material falling from feeder and an outlet or exit port provided in a substantially central area of said crushing chamber (20).
The vortex inner wall (55) and the vortex outer wall (60) run perpendicular to each other resulting in change of course of the colliding particles; wherein the said crushed feed material falling from feeder (30) is comminuted by a swirl flow along an internal perimeter wall of the crushing chamber (20) by the feed gas sprayed through constricted passage (40) of the said feed gas inlet (35). The pressurized feed gas coming through constricted passage (40) of inlet (35) entrains the crushed material and flows through the crushing chamber (20) causing a swirling vortex which accelerates the crushed material to move in a circular path within the crushing chamber.
The plurality horizontal air nozzles (45) are present tangentially at angle on annular outer wall of the crushing chamber (20) which expel a high-speed pressurized milling air/gas through a constricted passage in a closed space forcing the particles of crushed material to colloid with each other and on the walls of the crushing chamber (20).
The ancillary chamber (25) acts as secondary crushing chamber for the particles which are swayed into it due to the change in course by vortex outer walls (60) and vortex inner walls (55) where they undergo collision for longer duration to obtain finer particle size.
The outlet or exit port (50) may be optionally connected to the inlet of a high efficiency particulate air (HEPA) gas filter (104) which is connected to collecting jar (105) which collects the powder blocked by the gas filter.

In an embodiment the air jet milling equipment of present invention optionally comprise a top surface (10) and a bottom surface (15) made of corrosion resistant stainless steel frame and connected to rest of the parts by no means limited to the combination are fixed by fixtures such as plural bolts with nuts and screws. The jet mill optionally uses energy efficient 0.5 HP motor for operating the screw conveyer feeder and material scrapping.

OBJECT OF THE INVENTION
It is an object of the present invention to provide an air jet milling equipment which performs high-efficiency pulverization with less complex mechanical parts consuming less electricity and achieves more fine sized particles.
It is still another object of the present invention to provide an air jet milling equipment carrying out high-efficiency pulverization by an increase in the probability of collisions between the crushed material particles.
It is yet another object of the present invention to provide an air jet milling equipment carrying out high-efficiency pulverization by an increase in the duration of collisions between the crushed material particles.
It is still another object of the present invention to provide an air jet milling equipment suited to achieve good pulverization performance and good particle size distribution of the required material obtained via pulverization.
BRIEF DESCRIPTION OF THE DRAWINGS
The figure 1 illustrates the top surface of the air jet milling equipment of the present invention.
The figure 2 illustrates the bottom surface of the air jet milling equipment of the present invention.
The figure 3 illustrates the perspective view of the assembled air jet milling equipment of the present invention.
The figure 4 illustrates the cross-section of perspective view of the assembled air jet milling equipment of the present invention.
The figure 5 illustrates the working example of the air jet milling equipment of the present invention.
The figure 6 illustrates the movement of the particles of crushing material through the crushing chamber (20) and ancillary chamber (25) of the air jet milling equipment of the present invention.
The figure 7 illustrates the schematic view of the air jet milling equipment of the present invention in an embodiment.
DESCRIPTION OF THE INVENTION
The present invention discloses an air jet milling equipment which solves the aforementioned problems of the prior art by ensuring that particles obtained by the crushing process are finer, are of desired particle size and have a narrower size distribution of a higher classification precision. The crushing chamber of the air jet milling equipment is simple in configuration comprising a top surface and a bottom surface which can be easily separated and reassembled for cleaning both before and after milling.
In an embodiment as illustrated in figure 5, the air jet milling equipment comprises a flat circular hollow crushing chamber (20) made of a top surface (10) integrated with inner vortex walls (55), a bottom surface (15) integrated with vortex outer walls (60), an annular outer wall with plurality of air nozzles (45) to receive high-speed pressurized milling air/gas expelled through a venturi inside the hollow part of the crushing chamber (20), an ancillary chamber (25) in the form of annular classifying zone attached below the crushing chamber (20), a funnel shaped feeder (30) attached to the hopper for introduction of crushed feed material, a compressed feed air/gas inlet (35) directing the feed gas through venturi (constricted tube) (40) towards the crushed feed material falling from feeder and a funnel shaped outlet (50) protruding out of the crushing chamber (20) to receive micronized product, wherein the outlet (50) acts as an extraction hole for the vortex gases and entrained particles, extending away from the crushing chamber (20) along the central axis.
The crushed material is introduced into a horizontal circular hollow crushing chamber (20) from a funnel shaped feeder (30) which is comminuted by a swirl flow produced by a pressurized feed air/gas sprayed from a gas inlet (35) through a venturi (40) at an angle, the crushed particles are accelerated in a spiral movement inside the crushing chamber (20). This pressurized feed gas entrains the crushed material and flows through the crushing chamber (20) causing a swirling vortex which accelerates the crushed material to move in a circular path within the crushing chamber. The said crushed material further gets exposed to the high-speed pressurized milling air/gas expelled through a venturi (45) present tangentially at angle on the annular outer wall of the crushing chamber (20) causing a high pressurized air/gas flow inside a closed space forcing the particles to colloid with each other and on the walls of the crushing chamber (20).
The air jet milling equipment of present invention without any limitation may have a vibratory type conveyer feeder or a screw conveyer type feeder for feeding of the crushed material inside the jet mill depending on the requirement of the material to be milled.
The pulverization of the material primarily occurs due to collision impact between particles of the crushed material. The tangential velocity of the vortex generally increases towards the chamber central axis as the centrifugal force drives larger particles towards the perimeter while, the air towards the center sweeps fine particles. The vortex outer walls (60) and vortex inner walls (55) run perpendicular to each other at the central axis which change the course of these fine particles towards the annular classifying zone of ancillary chamber (25) where the fine particles undergo more collision for longer duration to obtain efficient pulverization of particles which on completion of milling process exit both the chambers through the funnel shaped outlet (50).
The figure 6 illustrates the path of movement of the particles in crushing chamber and change in course caused by the vortex walls. The crushing material undergoes collision in the crushing chamber (20) due to high velocity of air/gas coming from the air nozzle (venturi) (45). The tangential velocity causes movement of the smaller particles towards the central axis where the vortex outer walls (60) and vortex inner walls (55) run perpendicular to each other causing change in course of the movement of particles leading them to the ancillary chamber (25) where they collide with each other for longer duration to achieve more fine size. The fine particles are then swayed away from the outlet (50) to be collected as product.
The crushed materials inside the crushing chamber undergo collision between the incoming particles and the particles, which are already accelerated into the spiral path inside the crushing chamber (20). The centrifugal force drives the larger particles of crushed material towards the periphery of the crushing chamber (20) while the centripetal force creates the drag from the gas flowing from the nozzles (35, 45) along the wall of the crushing chamber (20) towards the outlet (50) in the center of the mill. The centrifugal force is greater than the centripetal force, causing the coarse particles from the periphery to return towards the center for crushing again.
The ancillary chamber (25) attached below the crushing chamber (20) in form annular classifying zone acts as secondary crushing chamber for the particles which are swayed into it due to the change in course by vortex outer walls (60) and vortex inner walls (55). As the crushed material undergoes collision for longer duration, more fine particle sized product is obtained through the outlet (50).
The milling action of the particle is because of the high velocity of air/gases instead of pins, jaws or hammers therefore preventing the heat generation during milling process. The adiabatic expansion of compressed air takes place with the resultant cooling effect. The heat-sensitive and low melting point materials are micronized without use of any freeze crushing methods.
The particle size distribution can be controlled and adjusted by pressure rate of air/ gas and feed rate of material. The obtained particles from the funnel shaped outlet (50) are trapped by specially designed cyclonic separator and finger-bag of non-woven polytetrafluoroethylene (PTFE) coated cloth bag without any risk of fiber contamination. The finger bag has specific shaking arrangement at set time of intervals for automatic cleaning which prevents risk of any contamination. The dust separator and collector are cylindrical and have a sanitary clamp for quick accessible connections. The present invention milling system is without a reverse jet in order to save air/gas consumption.
In an embodiment the air jet milling equipment may additionally comprise a high-efficiency dust separator combining inertial and static effects with membrane filter cartridges, a reverse-pulse, an automatic cleaning and a final safety high efficiency particulate air (HEPA) filter which can exhausts clean air to the atmosphere.
In an embodiment the air jet milling equipment of present invention optionally uses energy efficient 0.5 HP motor for operating the screw conveyer feeder and material scrapping.
In an embodiment, as illustrated in figure 3, the top surface (10) and the bottom surface (15) of jet mill along with rest of the parts by no means limited to the combination are fixed by fixtures such as plural bolts with nuts and screws. The jet mill is made of stainless steel frame which is highly corrosion resistant. The crushing/crushing chamber of the jet mill is compact and therefore occupies less space as compared to other available mechanisms.
The air jet milling equipment of present invention may be a fully automated or manual and may be mounted on an ergonomically designed portable stand with multiple options like micronizers, micro pulverizers and spiral fluidized air.

Example
In an embodiment as illustrated in figure 6 the schematic view of the air jet milling equipment (100) represents the milling gases and feed gases of high-purity nitrogen supplied from a liquid-nitrogen tanks used both for milling and feed gases. The high-purity liquid nitrogen is available with gaseous impurities of no more than 0.01%. The liquid-nitrogen tank supplies the gaseous nitrogen at desired pressure as per requirement and type of material to be milled. The supply line is divided into a mill gas line (106) and a feed gas line (107) connected respectively to the mill gas nozzle and the feed gas inlet of the jet mill (100). The supply regulators of both mill gas nozzle and feed gas inlet are adjusted as per desired requirements of the milling. The crushed material form hopper (108) is fed into the crushing chamber (101) via screw type conveyer feeder (109) having self-cleaning screws that are able to break the agglomerates and ensure an accurate speed controlled feeding. The jet mill (100) optionally utilizes 0.5 HP motor for screw feeder and material scrapping. The outlet (103) of the jet mill (100) may be optionally connected to the inlet of a high efficiency particulate air (HEPA) gas filter (104) which is connected to collecting jar (105) which collects the powder blocked by the gas filter. The particle size can be controlled by varying the gas feed pressure, the flow rates for the feed and mill gases. The material can be milled to an average particles size of 0.2 to 5 micron or coarse ground to 400 mesh depending upon characteristics of the product.

Jet mills
Jet mill used in the systems and devices described herein generally may include any jet mill configured to reduce an average particle size of a material to produce a ground material. The grinding chambers may be formed of stainless steel, and may include a coating of a liner. Examples of suitable liners include polyethylene, polytetrafluoroethylene, polyurethane, vulcanized rubber, tungsten carbide, etc.

Feed hopper
Feed hopper may include a container having a tapered bottom through which a material is discharged. In some embodiments, a feed hopper provides a material to a jet mill through a conveyor feeder by disposing a material on or in the conveyor feeder.

Feeder types
The jet mill system may use vibratory type conveyer feeder or screw type conveyer feeder. The vibratory type conveyer feeder is preferably used in pharmaceutical industries as it is mounted on the main platform without any bolting which allows easy removing for cleaning and the feed rate is controlled by adjusting the vibrator to get a more accurate feed rate. While screw type conveyer feeder can be a twin shaft feeder or volumetric type with a concave profile and with self-cleaning screws which break the agglomerates and ensure an accurate feeding of poor flowing products.

Material
The jet mill of present invention can be used for grinding various materials including, but not limited to, organic materials, inorganic materials, or combinations thereof. The materials subjected to jet milling systems described herein generally may include any material in particulate or crushed form.

Industrial Applicability
The Jet mill of present system can be used in pesticide industry for micronizing pesticide & herbicides, for producing polishing powders for polishing the lenses, computer hard disc or in toothpaste, in cosmetic industry to produce silky and smooth products.

The foregoing description explains the structure and the principles of operation of the preferred embodiment of the invention. The modifications may be made without departing from the scope of the present invention.
ADVANTAGES AND SIGNIFICANCE
The air jet mill equipment of present invention has following advantages:
1. High-efficiency pulverization performance by increasing the probability of collision between crushed material particles inside the crushing chamber.
2. Better particle size distribution of the fine powdered product obtained via pulverization.
3. High-efficiency pulverization performance by optimizing various pulverization conditions according to the type of crushed material or other such properties.
4. Alleviates the burden created by peripheral equipment such as compressors while achieving high performance.
5. Compact size and no requirement of extra mechanical parts.
6. The rings of the crushing chamber are replaceable with optimized crushing angles for various products. , Claims:1. An air jet mill equipment for crushing one or more substances comprising:
a) a flat circular hollow crushing chamber (20) made of a top surface (10) integrated with a vortex inner walls (55) and a bottom surface (15) integrated with a vortex outer wall (60);
b) a plurality horizontal air nozzles (45) on annular outer wall of the said crushing chamber (20) generating high-speed pressurized air flow through constricted passage;
c) an ancillary chamber (25) in the form of annular classifying zone in attached below the said crushing chamber (20);
d) a feeder (30) for introduction of crushed feed material;
e) a compressed feed gas inlet (35) directing the pressurized feed gas through constricted passage (40) towards the crushed feed material falling from feeder;
f) an outlet or exit port provided in a substantially central area of said crushing chamber (20);
wherein the said vortex inner wall (55) and said vortex outer wall (60) run perpendicular to each other resulting in change of course of the colliding particles;
wherein the said crushed feed material falling from feeder (30) is comminuted by a swirl flow along an internal perimeter wall of the crushing chamber (20) by the feed gas sprayed through constricted passage (40) of the said feed gas inlet (35).

2. The air jet mill equipment as claimed in claim 1, the said plurality horizontal air nozzles (45) present tangentially at angle on annular outer wall of the said crushing chamber (20) expel a high-speed pressurized milling air/gas through a constricted passage in a closed space forcing the particles of crushed material to colloid with each other and on the walls of the said crushing chamber (20).

3. The air jet mill equipment as claimed in claim 1, the said pressurized feed gas coming through constricted passage (40) of inlet (35) entrains the crushed material and flows through the crushing chamber (20) causing a swirling vortex which accelerates the crushed material to move in a circular path within the crushing chamber.

4. The air jet mill equipment as claimed in claim 1, wherein the said ancillary chamber (25) acts as secondary crushing chamber for the particles which are swayed into it due to the change in course by vortex outer walls (60) and vortex inner walls (55) where they undergo collision for longer duration to obtain finer particle size.

5. The air jet mill equipment as claimed in claim 1, wherein the said crushing chamber is optionally cylindrically shaped and the circulating gas flow is in form of a vortex about the central axis.

6. The air jet mill equipment as claimed in claim 1, wherein the said outlet or exit port (50) may be optionally connected to the inlet of a high efficiency particulate air (HEPA) gas filter (104) which is connected to collecting jar (105) which collects the powder blocked by the gas filter.

7. The air jet mill equipment as claimed in claim 1, wherein the top surface (10) and the bottom surface (15) is made of corrosion resistant stainless steel frame and is connected together to the rest of the parts by no means limited to the combination are fixed by fixtures such as plural bolts with nuts and screws.

8. The air jet mill equipment as claimed in claim 1, wherein the said air jet mill equipment optionally uses energy efficient 0.5 HP motor for operating the screw conveyer feeder and material scrapping.