Showing papers on "Jet mill published in 2007"

Preliminary Experimental Analysis of a Spiral Jet Mill Performance

Abstract: Jet mills are common devices used in industry for the fine milling of dry particulate materials. The size reduction is caused by repeated impaction events between particles. Although many parameters affect the performance of a jet-mill, only a few of them have been investigated by researchers to date. Furthermore, the published investigations test only a few materials. In order to bridge the knowledge gaps which exist, a new experimental apparatus was designed and constructed to enable experiments involving as many influencing parameters as possible. The new apparatus enables changing of the material feeding, mass flow rate, air flow rate, nozzle parameters (velocity, diameter, angle, number and shape), grinding chamber height and the classifier orientation. In this paper, preliminary experimental results concerning a number of the aforementioned parameters and their effect on the mill performance are presented.

Jet Mill Producing Fine Silicon Powder

Abstract: A method of jet milling silicon powder in which silicon pellets are fed into a jet mill producing a gas vortex in which the pellets are entrained and pulverized by collisions with each other or walls of the milling chamber. The chamber walls are advantageously formed of high-purity silicon as are other parts contacting the unground pellets or ground powder. The pellets and chamber parts may be formed of electronic grade silicon but polycrystalline silicon may be used for chamber parts. Additionally, the particle feed tube in which the particles are entrained in a gas flow and the vortex finder operating as the outlet at the center of the vortex may be formed of silicon. The milling and feed gas may be nitrogen supplied from a liquid-nitrogen tank lined with stainless steel. The feed pellets may be formed by chemical vapor deposition.

Numerical Study of Particle Motion in Jet Milling

Abstract: Jet mills are common devices used in industry for fine milling of dry particulate materials. The size reduction is caused by repeated events of impacts between particles. Although many parameters affect the performance of a jet mill, only a few of them were investigated. Particles' motions in a jet mill have great influence on the comminution process and energy consumption. Therefore, as a first step for a full simulation of the jet-mill process, it was decided to investigate the particle motion inside the jet mill by neglecting particle-particle interaction and particle breakage. In this way, the numerical simulations provide a better understanding of the classification process. In the present study, three-dimensional numerical simulations of particle motion in an industrial full-scale jet mill were conducted. The predictions of the numerical simulations were compared with experimental data and used to analyze the flow field characteristics.

Dispersible silica nano hollow particles and method for producing dispersion liquid of silica nano hollow particles

Abstract: PROBLEM TO BE SOLVED: To provide dispersible silica nano hollow particles and a method for producing the dispersion liquid of silica nano hollow particles wherein the coagulation of the silica nano hollow particles comprising a silica shell is prevented and the silica nano hollow particles can be dispersed in a solvent, a molten resin and the like as fine coagulated particles and can be mixed as a solid component in large amounts. SOLUTION: The high concentration dispersion liquid 5 of the silica nano hollow particles 1 consisting of the silica shell can be obtained by such steps that a step (S10) where n-hexane and a surface modifier are added to the silica nano hollow particles 1, stirred and dispersed with a high-speed stirrer, a step (S11) to obtain the fine coagulated particles having a size of about 0.5 μm or less by strong dispersion in a wet jet mill, a step (S12) for concentration in an evaporator, a step (S13) for performing surface modification in an autoclave at a supercritical state of n-hexane, steps (S14, S15) for redispersion by stirring and dispersing with the high-speed stirrer, a step (S16) to add a denatured silicone oil into a dispersed liquid, a step (S17) for performing ultrasonic dispersion by an ultrasonic dispersing machine and a step (S18) for performing classification and filtration. COPYRIGHT: (C)2009,JPO&INPIT

Method for producing very fine particles by means of a jet mill

Abstract: The invention relates to a method for producing very fine particles by means of a jet mill using compressed gases as the grinding gas, characterized in that the grinding gas is under pressure of ≦4.5 bar(abs).

Method for the production of very fine particles by means of a jet mill

Abstract: The invention relates to a method for producing very fine particles by means of a jet mill (1). The relative distance a/dDuse between at least approximately concentric milling jet inlets (5) whose center lines intersect at least approximately in one point is adjusted in accordance with the pressure of the working medium, a representing the jet length and dDuse representing the nozzle diameter.

Novel high efficiency fluidized bed type air flow mill

Abstract: The utility model relates to a new-type high-efficiency fluidized bed jet mill for crushing the solid materials, which comprises a machine frame; wherein the machine frame is provided with a grading chamber and a crushing chamber, the grading chamber is provided with a main shaft, a centrifugal wheel and a grading impeller, the cylinder lower end of the grading chamber is provided with the crushing chamber connected by a flange, the outer circumference of the cylinder body of the crushing chamber is provided with a plurality of combined-type crushing nozzles; as the crushing nozzle has a certain centripetal included angle, the materials form a junction in the cylinder center of the crushing chamber after jetted by the air flow; the impact and collision produces a greater jet force and expands the fluidization area of materials, which improves the crushing effect. The utility model is increased by 10 to 20 percent than the hour output of the single-hole crushing nozzle, the energy consumption is reduced by 20 percent, the finished-product yield of materials can reach 85 percent, and the yield of the existing crushing machine is 60 to 65 percent; the utility model has the compact structure and the convenient repair, maintenance and cleaning, can be widely used in the materials such as ink powder, lithium batteries and other industries which have the strict grading requirements for too large and too small particle content.

Jet milling from a particle perspective: predicting particle fracture based on mechanical material properties

Abstract: Milling is a very old discipline originated in milling agricultural products to flour Despite the enormous literature on size reduction, milling is a unit operation which has no sound underlying theory comparable to those existing for other unit operations The design of milling equipment for a given application is based on accumulated experiences of the manufactures It is not for lack of either interest or investigation that a quantitative theory of milling does not exist In contrast, the number of references in the literature dealing with milling is overwhelming This led to the belief that milling is an art which only could be learned by years of experience From the perspective of process control this is an undesirable situation This situation is specifically undesirable in the pharmaceutical industry where product control is critical Hence, there has been significant emphasis on the characterization and control of the properties of active pharmaceutical ingredients (APIs) The logical consequence of this trend is to characterize and control the particle size of the API throughout pharmaceutical processing Furthermore, in the pharmaceutical industry the successful development of new drug products is not only related to the discovery of new drugs, but also to the pharmaceutical development of an effective pharmaceutical dosage form Depending on the intended route of administration and several properties of the drug a specific particle size of the active pharmaceutical ingredient is required As a result pharmaceutical powders are often milled to achieve the optimum particle size Hence, during milling control of the drug substance particle size (distribution) is essential Jet milling is a well established technique for milling of pharmaceutically active compounds Inherent to processing of active pharmaceutical ingredients concomitant subtle changes in the physical state may occur In general the milling kinetics in a mill is described by the selection function, also often referred to as the rate of breakage function This selection function consists of two parts, representing the process parameters (the “mill function”) and the material parameters (the “material function”) The mill function represents the type of mill and processing conditions In this thesis the “material function” has been investigated more in depth and the material properties that are regarded as most important in jet milling are identified Chapter 1 summarises literature published so far regarding the relation between material properties and particle breakage behaviour It becomes clear that existing models used to predict particle breakage do not incorporate mechanical material properties As a consequence it is not possible to predict the particle size distribution of the milled material a priori In real-life pharmaceutical development it is often not possible to optimize milling conditions experimentally because the material is scarcely available Chapter 2 evaluates the relevant material properties involved in milling induced particle breakage The purpose of this study was to develop a method to predict the desired milling conditions given a specific (organic) solid material The selection function and the breakage distribution function are usually the starting points in modelling the milling process The selection function is the parameter that includes both material and mill properties Dimensional analysis made it possible to correlate the selection function with the material properties The model estimates the rate of breakage function, and needs mechanical material properties like hardness and yield strength as input to calculate the rate of breakage function A set of theories available in the literature enables prediction of the material properties For different compounds (lactose, paracetamol, a steroidal compound, and two heterocyclic compounds) the selection functions were calculated The calculations predict differences: lactose reduces slowly in size, while one of the heterocyclic compounds shows the most intense fracture Chapter 3 attempts to check the validity of the model by a series of experiments A comparison of the experimental results with the outcomes of the model using 5 different model compounds has been performed It appears that the rate of breakage function can be estimated by the equation as described in chapter 2 The model is able to rank the compounds in degree of fracture as an effect of milling It was also possible to perform a quantitative prediction of the impact of milling pressure on the particle breakage behaviour and to predict the particle size distribution after milling as well, incorporating process conditions and material properties Finally, it appeared that the prediction of the large particles in the distribution was significantly better than small ones Because the oversize material is usually the most critical parameter, the conclusion is that the model has acceptable practical applicability The model described in chapters 2 and 3 assumes that the ratio of the size of pre-existing flaws to particle size is constant Chapter 4 evaluates the effect of the pre-existing flaws in the material to be milled The particle rate of breakage of four samples of a model compound (sodium chloride), originating from different sources, was determined in a jet mill It appeared that each type of sodium chloride has a distinct particle rate of breakage and breakage pattern The numbers of flaws in the different types of sodium chloride particles have been determined by immersing the sodium chloride particles in a liquid with the same refractive index as sodium chloride has This makes the flaws and cracks better visible Microphotographs were made and flaws were counted manually This study shows that the flaw density has an impact on the fracture behaviour of particles The degree of fracture tends to increase with increasing flaw density This chapter also shows however, that the mechanical properties of the material as well as the starting particle size dominate the significance of the impact of flaws on fracture behaviour Often it is assumed that particle morphology influences particle fracture behaviour In order to investigate this assumption chapter 5 evaluates particle morphology and hardness of (pharmaceutically important) crystals The purpose of this study was to predict the hardness of crystals based on crystal morphology Unfortunately, anisotropy occurs during determination of the hardness Anisotropy is the phenomenon that directional differences occur in the physical properties of a material Literature reveals very clearly that anisotropy in hardness is determined by crystal structure and the primary slip system The slip system of a crystal was quantified on the basis of crystal structure, cohesive energy density and the hardness which was calculated from the mean yield pressure as obtained by compression tests Furthermore, the aspect ratios of the compounds were determined Based on theoretical considerations and experimental validation an inverse correlation between crystal’s morphology (represented by the aspect ratio) and the slip system of crystals has been established The hardness was predicted of four other compounds based on the correlation established in this chapter Subsequently, the predicted hardness was compared with the experimentally determined hardnesses as reported in literature Consequently, the hardness of crystals can be predicted using the crystal’s morphology and structure It is common practice to evaluate the particle fracture behaviour as an entangled effect of pre-existing flaws and cracks as well as mechanical material parameters Moreover, sometimes it is assumed that particle fracture behaviour is governed largely by pre-existing flaws Up to now, it was not clear whether either pre-existing flaws or mechanical material properties dominate particle fracture The purpose of chapter 6 was to investigate the effect of pre-existing flaws on mechanical material parameters Secondly, the aim was to correlate these properties with particle fracture in a jet mill in order to improve control of the milling process In this study the effect of pre-existing flaws on mechanical material properties of crystals of a model material, sodium chloride (like in chapter 4), from different sources have been investigated using optical microscopy, nanoindentation, and powder compaction Subsequently, these properties have been correlated with particle fracture in a jet mill Chapter 6 shows that particles that have a small average flaw size or high flaw density possess a relatively small constraint factor and hence behave more brittle whereas particles that have a high average flaw size have a high constraint factor and hence behave more ductile On the basis of an existing model the conclusion is that flaw density plays a more significant role than the average flaw size Chapter 6 shows that the rank orders of the mechanical material properties where consistent with the rank order of the experimentally determined particle rate of breakage Materials that have a relatively low hardness show the largest particle rate of breakage The degree of fracture tends to decrease for particles that have a smaller flaw density and hence behave more ductile It is concluded that crystal’s flaw size and density of flaws has an impact on the mechanical material properties and subsequently, on fracture behaviour of particles in a jet mill Therefore, unit-operations like crystallization which has an impact on impurities and flaws in crystals, influences also the fracture behaviour of particles in a jet mill

Jet mill and method for pulverizing material

Abstract: PROBLEM TO BE SOLVED: To improve pulverizing efficiency in a limited pulverizing chamber. SOLUTION: A plurality of collision portions X1 to X4 where jet streams are collided in the pulverizing chamber 2 are formed by providing a plurality of nozzle sets 8 in the pulverizing chamber 2. This allows the material P to be pulverized in a plurality of collision portions X1 to X4, thereby enabling the system to efficiently pulverize the material P. COPYRIGHT: (C)2009,JPO&INPIT

Jet mill of spiral flow type

Abstract: A swirl type jet mill is provided to increase milling efficiency without minimizing the speed reduction of a swirl current by a spiral guide blade and to improve classification efficiency by installing a circular arc-shaped guide blade. The swirl type jet mill is composed of a milling chamber(100); a supply nozzle(200) for forming a swirl current by jetting materials to be crushed and the air together into the milling chamber; an auxiliary nozzle(300) for jetting the air into the milling chamber to maintain and reinforce the swirl current generated in the milling chamber; a discharge port(400) for discharging the crushed materials and the air; and a plurality of spiral guide blades(110) installed in the milling chamber and arranged on a concentric circle about the discharge port.

Use of Spouted Bed Type Binderless Granulation to Design PLGA Nano-composite Granules for Dry Powder Inhalation

Abstract: New granulation technique using a spouted bed type binderless granulator and a jet mill to make PLGA nano-composite granules applicable to DPI was studied. In the method, the PLGA nano-composite granules having a spherical shape with soft granule strength can be binderlessly granulated in the spouted bed using raw materials prepared by milling and blending freeze dried PLGA nanospheres and lactose powder as an excipient with a jet mill. The prepared nano-composite granules showed good handling properties with high respirable fraction (RF) values estimated by cascade impactor in vitro. The new method proposed in the present work proved to be a useful preparation technique of PLGA nano-composite granules for DPI application.

Process for preparing ground resin particles and apparatus for preparing the same

Abstract: A process for preparing ground resin particles is provided by modifying a jet mill with opposed fluidized bed. By using a jet mill having a plurality of jet nozzles disposed at predetermined positions in a barrel of a grinding chamber toward the injection point of the grinding chamber and a bottom wall having a flat surface in part or in whole, parallel to the jet nozzles, or having a conical projection immediately below the injection point, resin particles to be ground are jetted with or without water, thereby being ground to obtain ground resin particles of an intended particle size.

Preparation of Nanometer Alumina Particles with Opposed Jet

Abstract: The opposed jet mill was used to prepare nanometer alumina particles.It is concluded that preparing nanometer alumina particles by opposed jet is feasible.Meanwhile,modifying the surface of the alumina particle before grinding can reduce the particle's surface energy and prevent the fine particles from aggregating.

Method for manufacturing slurry to be used for source material for manufacturing silicon carbide, method for manufacturing secondary particle and method for manufacturing single crystal silicon carbide

Abstract: PROBLEM TO BE SOLVED: To provide a method for manufacturing a slurry containing primary particles of carbon and silica and suitable for the manufacture of a single crystal silicon carbide, and to provide a method for manufacturing spherical secondary particles and a method for manufacturing a single crystal silicon carbide. SOLUTION: The method for manufacturing a carbon-silica-containing slurry includes a mixing step of adding carbon and silica to a dispersion medium to obtain a mixture and a dispersing step of treating the obtained mixture with a jet mill. The method for manufacturing carbon-silica-containing spherical secondary particles includes, in succession to the steps, an atomizing step of atomizing and drying the obtained slurry. The method for manufacturing a single crystal silicon carbide includes, consecutively, a crystal growing step of supplying the secondary particles, through source material supply pipes 36, 36'onto the surface of a seed crystal 34 in a crucible 32 kept in a high temperature environment. COPYRIGHT: (C)2008,JPO&INPIT

Method of dispersing ultrafine inorganic powder in thermoplastic resin

Abstract: A method of dispersing super-minute inorganic Powder body in thermoplastic resin, the manipulation step is: first mixing the super-minute inorganic Powder body and organic reshaping intercalated montorillonite clay, getting compound powder body by shattering mixed powder body repeatedly with jet mill and ball mill, after adding solvent to pellet, it is together with thermoplastic in single/ double bolt forcer to liquate and mix, extrude, cut granule, get finished product.The merit of this invention is: (1)Based on the method of Melt blending through improving powder compound pattern to solve dissipation problem of micropowder, it is a new dissipation method; (2) dissipation method' technology is simple, production cost is low, it has little damage to resin efficiency;(3)Not pollute environment.

Effect of grinding techniques on absorbing characteristics of short iron fibers

Abstract: Microwave-absorbing properties of iron fibers can be adjusted by their aspect ratio. This paper presents several modification techniques for grinding long iron fibers to a suitable aspect ratio. The grinding instruments include pulsator, jet mill and muller. The aspect ratio distribution, microstructure, electromagnetic parameter and reflectivity of the samples were analyzed and discussed in detail. The results show that the fractions of 5

Manufacturing technique for high aspect ratio wollastonite powder

Abstract: Provided is a manufacturing method for high aspect ratio(1:15 or higher) wollastonite powder to more efficiently produce a filling agent applied to a variety of fields including PCB, paper, paint, and so forth The high aspect ratio wollastonite powder is manufactured by crushing rude ore; inputting the crushed rude ore into a single runner mill with help of a screw-type feeder until an average of 90±5 micrometer size powder is obtained; storing the powder in a storage tank; inputting again the wollastonite powder into a fluidised bed opposed jet mill with help of a screw-type feeder until an average of 6-15 micrometer size powder having both coarse particles and fine particles is obtained; and storing the resulting wollastonite powder in a storage tank

Finely-divided powder of wood charcoal and/or carbon powder pigment, master batch and molded article

Abstract: PROBLEM TO BE SOLVED: To form wood charcoal and/or carbon powder pigment each having high safety as a food additive into a finely divided powder thereof, to provide a master batch using the finely-divided powder with high dispersibility thereof and to provide a molded article such as a film, a fiber or the like for a variety of synthetic resin products using the master batch. SOLUTION: The finely-divided powder is formed of wood charcoal and/or carbon powder pigment wherein 70% or more of the finely-divided powder has an average particle size distributed in a range of 0.5-30 μm. The finely-divided powder is formed by pulverizing by the use of a jet mill provided with a plurality of pulverizing nozzles for jetting a high-pressure jet stream disposed at positions where the circumference of the mill is equally divided wherein one or more of the pulverizing nozzles are nozzles for feeding a raw material to be pulverized. COPYRIGHT: (C)2007,JPO&INPIT

Method for producing very fine particles with a jet mill and jet mill for same

Abstract: The present invention relates to a method for producing finest particles by means of a jet mill (1), wherein as the means (B) a fluid, in particular gases or vapors is used, which has a higher speed of sound than air (343 m / s). Furthermore, the invention provides a jet mill (1) for producing very fine particles, wherein a source for a resource (B) is included or associated with a higher velocity of sound than air (343 m / s).

Particulate distributor and jet mill

Abstract: PROBLEM TO BE SOLVED: To provide a jet mill whose treatment capability can be greatly improved without increasing the installation surface area and a particulate distributor usable for various particulate distribution uses other than the jet mill. SOLUTION: The jet mill comprises a jet mill main body to form a disc-like cavity, a plurality of air nozzles installed in a ring-like outer wall of the jet mill main body for generating high speed air current in the disc-like cavity, and an outlet positioned at approximately the center of the disc-like cavity of the jet mill main body, wherein the jet mill has a configuration in which the jet mill main bodies whose disk-like cavities each forms a ring-like crushing zone for crushing an object to be crushed by the high speed air current supplied from a plurality of the air nozzles are stacked in a plurality of steps, and a particulate distributor having particulate distributing functions in a number corresponding to the number of the stacked jet mills is installed on the top step of the jet mills stacked in the plurality of steps. COPYRIGHT: (C)2007,JPO&INPIT

Method of manufacturing fine talc particles

Abstract: PROBLEM TO BE SOLVED: To provide a method of industrially manufacturing fine talc particles. SOLUTION: The method of manufacturing the fine talc particles which have 0.05-1 μm number average particle diameter and 50% of which have 0.1-0.9 μm particle diameter is carried out by charging a white powdery talc particles expressed by a chemical formula, Mg 3 Si 4 O 10 (OH) 2 into a wet or dry jet mill and/or bead mill and pulverizing. COPYRIGHT: (C)2007,JPO&INPIT

Method for production of ultradispersed powder from unossified antlers of maral and siberian stag

Abstract: FIELD: biotechnology, food processing industry, medicine. ^ SUBSTANCE: claimed method includes unossified antler cutting, freezing and crushing together with skin or wool and skin to produce particles having size of at most 0.5 mm, drying and additional crushing in jet mill to produce particles having size of at most 0.1-30.0 mum. Drying of crushed frozen material is carried out simultaneously with additional crushing in jet mill, in gas medium flow with humidity of at most 10 mass % wherein temperature of gas flow in jet mil is automatically maintained at +50°C or less. Produced target ultradispersed powder contains non-radioactive carbon isotope C13 in amount of at least 1.3 % based on total carbon content in finished product. Frozen and crushed material is periodically loaded into jet mill with interval sufficient to produce yield of 70 mass % or more. Period of simultaneous drying and crushing of one material portion between loading cycles is not longer than 1.5-5 hours. ^ EFFECT: simplified technology, target bioactive product of improved quality. ^ 3 cl, 3 ex, 1 tbl, 2 dwg

Effect of Disagglomeration on the Recovery of Abrasives from Waste Sludge

Abstract: Effect of disagglomeration with different type of mill on recovery of abrasives was investigated. To evaluate an effect of disagglomeration on recovery of abrasive from waste sludge, disagglomerated waste sludge by different mills were air classified and yield of fine particles product were calculated. The results suggested that pin mill and jet mill are effective for disagglomeration of waste sludge. Pumice, garnet and rouge powders were easily recovered by air classification after disagglomeration by pin mill for the recycling of them as a abrasive powders in polishing procedure of CRT glass. Comparing to raw abrasive powders, shapes and mineralogical properties were very similar to those of new ones. These results suggest that the recycled abrasive powders can be used as an abrasive powders.

Microstructure characterization of mechanically activated nanocrystalline quartz using xrd line broadening

Abstract: Mechanical activation of quartz was carried out in jet mill at various specific kinetic energy level and classifier speed. The characterization of the particle size, crystallite size, amorphism rate and lattice strain was conducted on the feed and mechanically activated particles. The area under the prominent quartz peak was used to calculate the amorphism rate of the mechanically activated particles. Scherer equation was used to determine the crystallite size of the feed and mechanically activated particles. Mean particle size less than 5μm was obtained when the specific kinetic energy is ranging between 500 kWh/ton and 1000 kWh/ton. Amorphism of the mechanically activated particles up to 18% was observed at 500 kWh/ton. The crystallite size and lattice strain is influence by the intensity of the specific kinetic energy and classifier speed. The reduction in the crystallite size up to 39% was observed where the minimum crystallite is 23nm. The lattice strain is ranging from 0.024 to 0.038 respective to the specific kinetic energy and classifier speed.