Jet mill

About: Jet mill is a research topic. Over the lifetime, 803 publications have been published within this topic receiving 5686 citations.

Preparation of electrostatic image developing toner

Abstract: PURPOSE:To effectively obtain an electrostatic image developing toner causing low fog at a small cost of power, by preliminarily pulverizing a roughly crushed toner material with an impact breaker, and finely pulverizing it with a jet mill. CONSTITUTION:A raw toner material consisting of synthetic resin, carbon black, etc. is roughly crushed with a hammer mill, etc., and preliminarily pulverized with an impact breaker having a rotor 2 provided with beater blades 2a so as to make weight average particle diameter not to exceed 50mum. Then, it is further micropulverized by beating the pulverized particles 1 with ultrahigh speed air streams injected from a jet nozzle 4 using a jet pulverizer, thus permitting both advantages of the impact and jet pulverizers to be adopted, microparticles causing fog to be prevented, and an intended electrostatic image developing toner to be effectively obtained.

Production of fine fused spherical silica

Abstract: PURPOSE: To obtain fine fused spherical silica in good yield by melting a silica raw material with a frame formed by combustion of a combustible gas and oxygen and introducing a cooling gas into a flame-forming zone. CONSTITUTION: A silica raw material is melted with a flame formed by combustion of a combustible gas and oxygen to produce fused spherical silica. In the process, a cooling gas is introduced into a frame-forming zone. The silica raw material used is preferably natural or synthetic silica of a as high a purity as possible. Purified quartzite, quartz sand, rock crystal, etc., are cited as the natural silica and silica which is a hydrolyzate of an organosilicate, such as ethyl silicate, prepared by hydrolyzing a silicon halide or neutralizing an aqueous solution of an alkali silica, etc., is cited as the synthetic silica. The above- mentioned silica raw materials are finely pulverized in a desired pulverizer, such as ball mill or jet mill. In most cases, the average particle diameter is ≤10μ, preferably within the range of 2-8μ. COPYRIGHT: (C)1990,JPO&Japio

Production of organic powder and organic powder

Abstract: PROBLEM TO BE SOLVED: To impart shape and size fit for a modifying material to an org. substance to be pulverized without deteriorating characteristics peculiar to the stock by pulverizing the org. substance with a rolling ball mill, etc., and further pulverizing it with a jet mill. SOLUTION: A polysaccharide such as cellulose or chitin as an org. substance to be pulverized is pulverized to about 20μm average particle diameter with a rolling ball mill, a tube mill, a rod mill or a hammer mill. The pulverized substance is further pulverized to about <=10μm average particle diameter with a jet mill. The org. substance is pulverized to fine particles in two stages and the objective org. powder whose size is fit for utilization as a modifying material is easily obtd.

Wet process amorphous silica and method of manufacturing the same

Abstract: PROBLEM TO BE SOLVED: To provide a wet process silica which enables easy adjustment of the particle size and which can be finely pulverized easily, while it is formed of wet process amorphous silica. SOLUTION: The wet process amorphous silica has a degree (Pco) of cohesive property of 1.0-1.25 and ≤7% equilibrium moisture content at 25°C and 75% RH for 48 hr. The degree (Pco) of cohesive property is defined by the relation (1) of Pco=B/A where A expresses a volume-based median diameter (D 50 ) by a laser diffraction method of pulverized slurry obtained by critically pulverizing water-based slurry of the amorphous silica adjusted to 2-40 wt.% concentration using a wet pulverizer such as a ball mill and B expresses a volume-based median diameter (D 50 ) by the laser diffraction method of powder obtained by drying the pulverized slurry and critically pulverizing with a dry pulverizer such as a jet mill. COPYRIGHT: (C)2004,JPO&NCIPI

Predictive Milling of Active Pharmaceutical Ingredients and Excipients

Abstract: Spiral jet milling is a size reduction process used in various industries, ranging from paints to food and pharmaceuticals. It has great benefit in the pharmaceutical industry due to its ability to reduce particulate solids to micron sizes and narrow size distributions. Despite its heavy usage, the underlying size reduction mechanism of the mill is not well understood. However it is generally known that the milling behaviour is dependent on the grinding conditions of the mill, as well as the materials physical and mechanical properties. The system is also very energy inefficient. In this work the milling behaviour of active pharmaceutical ingredients and excipients in the spiral jet mill has been analysed based on their mechanical properties, as established from the Ghadiri and Zhang semi-brittle breakage model. Using the Single Particle Impact Test Rig, the breakability index (αH/KC2) of three pharmaceutical materials (paracetamol, aspirin, and α-lactose monohydrate) is determined. It is shown that the order of breakability is paracetamol > aspirin > α-lactose monohydrate. For milling studies the Hosokawa Alpine Aeroplex Spiral Jet Mill 50AS is used. The change in specific surface area (ΔSSA) due to milling is quantified by size analysis and related to the breakability indices. The order of ΔSSA is α-lactose monohydrate > paracetamol > aspirin at high grinding pressure conditions. The loading of particles in the grinding chamber of the mill is found to be an important characteristic for the classification of milled materials in addition to the effects of centrifugal and drag forces. Numerical simulations have been carried out and used to analyse the behaviour of the spiral jet mill. Using Computational Fluid Dynamics, the mechanics of internal particle classification by size of the 50AS has been analysed. Particles of 2 µm and less are shown to be classified. The Discrete Element Method is coupled with Computational Fluid Dynamics to investigate the effect of grinding conditions and particle properties on the particle motion and fluid-particle energy transfer, including gas pressure, the number of particles and the particle size distribution. A very small amount of energy is transferred to the particles from the fluid, highlighting the energy inefficiency of the system. Interparticle interactions are found to have a greater amount of dissipated energy compared to particle-wall interactions, which suggests interparticle collisions are the primary source of particle breakage. The majority of the stress exerted on the particles is close to the wall of the mill, with the normal stress being greater than the shear stress. A very low proportion of particles are found to be in contact at a given time, indicating particle breakage occurs from instantaneous collisions rather than particles shearing against each other. Finally the potential for scale-up of the spiral jet mill is investigated based on the fluid power input to the system. There is a good comparison of the ΔSSA of α-lactose monohydrate milled in four different mills at similar fluid power input conditions. Two of the mills are the 50AS and the Hosokawa Alpine Piconizer (33 AS), and the other two are of different design but with internal diameters of 2 inches and 4 inches, i.e. roughly similar size to the Hosokawa mills. The latter two mills had a greater fluid power as the grinding nozzle diameters are larger than the Hosokawa mills.