Showing papers on "Jet mill published in 1988"

Fine graphite powder

Abstract: PURPOSE:To provide fine graphite powder having satisfactory slidability, low light transmissivity, low surface electric resistance, a low coefft. of friction and other superior function by graphitizing carbon fibers produced by a vapor process and by pulverizing the resulting graphite fibers. CONSTITUTION:Carbon fibers produced by a vapor process are graphitized in a nonoxidizing atmosphere or the like and the resulting graphite fibers are pulverized with a jet mill or the like to obtain fine graphite powder of <=1mum particle size. This graphite powder has low light transmissivity, low surface electric resistance and a low coefft. of friction, so it is suitable for use as a coating agent for a sound tape, a videotape or the like.

Method and device for micronising solids in a jet mill

Abstract: Die vorliegende Erfindung betrifft ein Verfahren zum Mikronisieren von Feststoffen in Strahlmuhlen, wobei die Feststoffe uber einen Injektor in die Strahlmuhle eingebracht werden und wobei die Mikronisierung gegebenenfalls in Gegenwart von Mahl- und/oder Dispergierhilfsmitteln erfolgt, wobei die Feststoffe dem Injektor zwangsweise zugefuhrt werden. The present invention relates to a method for micronising solids in jet mills, the solids are introduced via an injector into the jet mill and the micronisation optionally effected in the presence of grinding and / or dispersing agents, whereby the solids are forcibly supplied to the injector.

Pulverizing and coating device

Abstract: PURPOSE: To improve the pulverizing and coating efficiency of the pulverizing and coating device for which a jet mill having an internal classifying mechanism of a flat vortex type is used by specifying the ratio of the diameter of a discharge pipe/the diameter of a classifying zone to ≤0.4. CONSTITUTION: The ratio of the diameter De of the discharge pipe/the diameter Di of the classifying zone of the pulverizing and coating device for which the jet mill having the internal classifying mechanism of the flat vortex type, i.e., the opposite type jet mill, is used is specified to ≤0.4. More preferably, the discharge port 8 of the classifying chamber has the shape consisting of a curved surface or the combination of continuous lines in the inlet and the outlet part is made into the shape having an enlarged part. In addition, a pulverized product passage 6 entering the classifying zone B from a pulverizing zone A is so constituted that the gas and pulverized product flow into the passage from nearly the entire circumference. Further, the passage is so constituted that the gas and the pulverized product are admitted from the classifying circle C of the classifying zone B to the outer side. The pulverized product of a submicron class is easily obtd. by this constitution. COPYRIGHT: (C)1990,JPO&Japio

Process and device for micronizing solid matter in jet mills

Abstract: A process for micronizing solid matters in a jet mill, wherein the solid matters are brought into the jet mill across an injector and wherein the micronization takes place, if necessary, in the presence of milling aids and/or dispersing agents, wherein the solid matters are forcibly supplied to the injector and an apparatus for carrying out the process, the apparatus comprising a dosing means, a forcible entry means, and injector and a jet mill.

Particle size characterization of a jet mill product via principal component analysis

Abstract: A powerful statistical technique, principal component, analysis, can be used to characterize the product particle size distribution of a jet mill. Usually the average and variance of a product size distribution are used to characterize or specify the product. With principal component analysis, a broader spectrum of the product distribution can be characterized by only one or two principal components. Using these principal components in reverse, one can approximately reconstruct the particle size distribution. These principal components can also be treated as response variables and regressed against operating variables of the micronizing process. The technique employed in this study thus offers: 1. a useful method for characterizing the jet mill product size distributions, and can be directly adapted in powder production operations. 2. an alternate basis for comparing jet mill configurations and operating conditions.

Production of high-purity fine graphite powder

Abstract: PURPOSE: To efficiently obtain high-purity fine graphite powder with ≤50ppm impurity content by roughly crushing a graphite material, subjecting the crushed material to highly purifying treatment with a high-temperature halogen gas and finely pulverizing the resultant material in a jet mill. CONSTITUTION: A graphite material is converted into high-purity fine graphite powder by pulverization and high-temperature halogen gas treatment. In the process; the material is treated as follows. That is the graphite material is initially roughly crushed and then subjected to highly purifying treatment with the high-temperature halogen gas. The roughly crushed material after the highly purifying treatment is then finely pulverized into particles having ≤1μ average particle diameter by pulverization with a jet mill to afford the objective high- purity fine graphite powder. Although the jet mill includes two types in which raw materials are made to mutually collide using jet air streams and the raw materials are blown onto a collision plate with the jet air streams, a mechanism belonging to the former type is preferably used. COPYRIGHT: (C)1990,JPO&Japio

Production of sintered rare earth element-iron-boron magnet

Abstract: PURPOSE:To produce a sintered rare earth element-iron-boron magnet having superior magnet characteristics by allowing gaseous hydrogen to be absorbed in a rare earth element-iron-boron material to crush the material, pulverizing the crushed material with a jet mill, press-forming the resulting fine powder in a magnetic field and sintering it. CONSTITUTION:A rare earth element-iron-boron material is subjected to evacuation treatment preferably under heating to nearly perfectly remove adsorbed gas and the material is crushed by allowing gaseous hydrogen to be absorbed in the material at about 50-200 deg.C. The crushed material is pulverized to several mum average particle size with a jet mill without carrying out dehydrogenation. The oxygen content in the atmosphere in the jet mill has been made as low as possible. The resulting fine powder is press-formed in a magnetic field and sintered preferably at about 1,000-1,100 deg.C. The sintered body is heat treated at a proper temp. A magnet having high performance is safely obtd. at a low cost.