Showing papers on "Jet mill published in 2021"
TL;DR: In this paper, it is shown that increasing the depth of the particle bed reduces the fluid phase tangential velocity in the proximity of the classifier, as momentum is exchanged with circulating particles.
13 citations
TL;DR: In this paper, a mathematical power model is proposed to describe the effect of feed rate and air pressure on the final flour particle size and energy consumption, and the energy-size reduction equations revealed that the particle size, as well as the energy consumption were mainly influenced by FR and to a lower extent by AP.
8 citations
TL;DR: In this article, the influence of grinding pressure, holdup and milling time on the performance of a spiral air jet-mill operating in a batch mode, with respect to the particles, was studied by means of experiments, indicating that mean size is primarily dependent on the energy supplied.
8 citations
TL;DR: In this article, the authors investigate particle dynamics in a 50mm spiral jet mill through coupled CFD-DEM simulations and find that the particle velocity was affected by both the particle loading and operating pressure.
Abstract: Spiral jet mills are ubiquitous in the pharmaceutical industry. Breakage and classification in spiral jet mills occur due to complex interactions between the fluid and the solid phases. The study of these interactions requires the use of computational fluid dynamics (CFD) for the fluid phase coupled with discrete element models (DEM) for the particle phase. In this study, we investigate particle dynamics in a 50-mm spiral jet mill through coupled CFD-DEM simulations. The simulations showed that the fluid was significantly decelerated by the presence of the particles in the milling chamber. Furthermore, we study the particle dynamics and collision statistics at two different operating conditions and three different particle loadings. As expected, the particle velocity was affected by both the particle loading and operating pressure. The particles moved slower at low pressures and high loadings. We also found that particle–particle collisions outnumbered particle–wall collisions.
6 citations
TL;DR: In this paper, the effect of grinding nozzles pressure on the particle dynamics and fluid flow was analyzed by numerical simulation, showing that the average velocity gradient in the radial direction is very steep for low mass loadings, indicative of rapid shearing, but it decreases significantly as the particle mass loading is increased.
5 citations
TL;DR: In this paper, the authors describe the comminution process that takes place in the jet mill using a modified form of the thermodynamic theory of grinding, where new material characteristics have been added: the surface and volumetric density of grinding energy.
Abstract: Raw materials are used in many industrial technologies. The raw material frequently has to be prepared as an intermediate with an appropriate particle size distribution, which requires the use of grinding. In grinding processes, energy consumption is a very important profitability criterion for the applied particular size reduction technology. The paper describes the comminution process that takes place in the jet mill using a modified form of the thermodynamic theory of grinding. In this theory, new material characteristics have been added: the surface and volumetric density of grinding energy. The thermodynamic theory is a combination of the classical Kick’s theory and the modified form of Rittinger’s theory. The tested physical magnitudes are a measure of the energy consumption of the grinding process. They describe the energy that must be provided in the grinding process to overcome interactions between particles related to the volume and surface of the material. Knowledge of these magnitudes is necessary to model thermomechanical phenomena in the solid state. The paper presents the results of research on comminution in a jet mill, on the basis of which the values of the tested material magnitudes were determined. It is graphically shown how the values of the tested magnitudes depend on the grain size of the ground samples.
3 citations
TL;DR: In this article, steam jet milling was applied for the first time to ultra-fine grind the filter cake (moisture content 23.80%) produced by a kaolin concentrator.
Abstract: Steam jet milling was applied for the first time to ultra-fine grind the filter cake (moisture content 23.80%) produced by a kaolin concentrator. The material was dehydrated and dried simultaneously during grinding, and the final ground sample met the moisture content requirement for powder products of <2%. The particle size of the ground kaolin samples decreased and the particle-size distribution was more concentrated, indicating that the steam jet milling was more effective for kaolin processing than the conventional dry grinding process. In addition, steam jet milling can improve the whiteness and decrease the crystal order of the samples, thus improving the kaolin properties in follow-up applications.
3 citations
2 citations
TL;DR: In this article, a spiral jet mill was simulated using Discrete Element Method (DEM) and Computational Fluid Dynamics (CFLD) models and the particle behavior and fluid motion were analyzed as a function of hold-up and grinding pressure.
Abstract: A spiral jet mill was simulated using Discrete Element Method modelling and Computational Fluid Dynamics. The particle behaviour and fluid motion were analysed as a function of hold-up and grinding pressure. Particle collision energy was predicted to be prevalent along the bed surface and in front of the grinding jets, as shown through the collision data recorded. The bed itself affects the fluid flow field, as momentum is transferred to the particles. Increasing the grinding pressure does not result in a proportional increase in the kinetic energy of the particle system, as the high pressure jets begin to penetrate the bed with greater ease. The particle bed moves as ‘plug-flow’, with the layers of the bed closest to chamber wall.
2 citations
TL;DR: In this article, the fluid-dynamics of a 3D, real-scale spiral jet mill when caking is occurring are investigated. But the authors only consider the case where the nozzles inlet pressure and the chamber diameter are varied to mimic the condition generated by the aggregates formation during the micronizaton process.
Abstract: In this work we present a method to investigate the fluid-dynamics of a 3D, real-scale spiral jet mill when caking is occurring. CFD simulations are employed to deeply study the pressure and the velocity fields of the gas phase when the nozzles inlet pressure and the chamber diameter are varied to mimic the condition generated by the aggregates formation during the micronizaton process. The computational model is built replicating the experimental observation consisting in the fact that most of the crusts form on the outer wall of the chamber. Simulations underline that caking causes the deterioration of the classification capabilities of the system if the gas mass flow rate is kept constant at nozzles, allowing larger particles for escaping the system. It is shown that it is possible to mitigate this phenomenon by gradually reducing the gas mass-flow rate to keep constant the nozzles absolute pressure. This keeps unchanged the fluid spin ratio and the classification characteristics when caking is advancing.
1 citations
TL;DR: In this article, Cactus (Opuntia ficus-indica) cladodes were dried at 45°C for 24h, followed by an 18h vacuum drying at either 60°C or 60°c.
Abstract: Cactus (Opuntia ficus-indica) cladodes are a source of dietary fiber, vitamins and antioxidants that could be utilized by the food industry for both their nutritional and technological properties. In the present study, cladodes were dried at 45°C for 24 h, followed by a 18 h vacuum drying at 45°C or 60°C. The dried cladodes were then ground in a grain mill, resulting in two coarse cladode flours (C45 and C60, respectively). A portion of the two flours was further ground with jet mill, yielding two fine flours, J45 and J60, respectively. Color, bulk density, water and oil holding capacities, solubility and dietary fiber content were determined. In addition, rheological properties and sedimentation kinetic of aqueous cladode flour suspensions were evaluated. An increase of insoluble fiber was observed with micro-grinding. All samples exhibited shear thinning behavior, while jet milling led to substantial decrease in apparent viscosity values. Coarse fractions sedimented quickly, achieving almost maximum sedimentation within 10 min, while the micro ground samples sedimented half as fast. In conclusion, particle size significantly alters the technological properties of cladode flour, broadening the range of applications cladodes could be used for.
01 Mar 2021
TL;DR: The relevance of the subject of this work is determined by the need to reduce the energy consumption of fine grinding by controlling the process, which is proposed to implement based on the results of acoustic monitoring, and jet grinding is presented as a control object.
Abstract: The relevance of the subject of this work is determined by the need to reduce the energy consumption of fine grinding by controlling the process, which is proposed to implement based on the results of acoustic monitoring The paper describes the operation of a jet mill in a closed cycle It is known that fine grinding refers to energy-intensive production, but jet grinding is indispensable in obtaining thin and ultra-thin "pure" materials, ie materials without the introduction of any impurities And with the creation of a new way to control the process, there is a real opportunity to reduce energy consumption by jet mills while maintaining optimal performance Based on the process parameter analysis input and output disturbing and control process parameters are selected In this way, jet grinding is presented as a control object The problems of jet grinding and ways to solve them are shown This became the basis for further construction of automatic process control based on the acoustic signals of the grinding zone
01 Apr 2021
TL;DR: In this article, the internal flow field is simulated by computational fluid dynamics (CFD) modelling to analyze the pressure field, velocity field and turbulent energy field, and the results show that the cuttings have good acceleration and pulverization performance in the accelerating tube.
Abstract: Jet Mill Bit (JMB) is used to reduce the cuttings bed in horizontal drilling. In this paper, the internal flow field is simulated by computational fluid dynamics (CFD) modelling to analysing the pressure field, velocity field and turbulent energy field. At the same time, the DPM model is also used to simulate the particle field. The results show that the cuttings have good acceleration and pulverization performance in the accelerating tube. The drilling fluid generates high-speed injection when passing through the reverse nozzle outlet resulting in negative pressure in the acceleration tube, which generates suction force at the bottom of the well and accelerates the return of the cuttings and the maximum pressure drop is close to 0.5Mpa. The work done in this paper is instructive for the optimization design of Jet Mill Bit and it is expected to promote its field application.
TL;DR: In this paper, an arc melting method was used to prepare the Mn50Bi50 alloy and the homogenized alloy was subjected to jet milling at different feed rates from 0.5 to 1.5 g/min.
Abstract: Mn50Bi50 alloy was prepared using arc melting method with subsequent homogenization treatment. The homogenized alloy was crushed and subjected to jet mill at different feed rates. The weight fraction of the LTP MnBi phase determined by the Rietveld refinement of the XRD pattern was found to be 89% in the as-homogenized and crushed alloy. The crushed alloy was subjected to jet milling at different feed rates from 0.5 to 1.5 g/min. Structural studies show that increase in feed rate leads to phase decomposition. Magnetic studies show that as-homogenized crushed alloy exhibits a magnetization of 60 emu/g. Jet milling leads to increase in coercivity and a decrease in magnetization. However, it was found that increase in the feed rate during jet milling leads to decrease of both coercivity and magnetization. Microstructural studies show that jet milling leads to decrease in particle size. Jet milling done at a lower feed rate helps in yielding the lowest average particle size compared to remaining feed rates in the Mn-Bi alloy. The spin reorientation transition temperature of the Mn-Bi alloy decreases with jet milling and varies at different feed rates. The coercivity of the Mn-Bi powder jet milled with a lower feed rate increases from 14.7 kOe at room temperature to 19.4 kOe at 400 K.
TL;DR: In this article, a mathematical description of the two-phase flow motion at the outlet of the vertical acceleration tube of a jet mill with a plane grinding chamber of torus-shaped form is presented.
Abstract: Nowadays building material industry as well as other industry branches exercise bigger demand to use powders with high dispersion. Jet mills are used to produce such powders, that’s why development of new jet mill designs, increase of grind efficiency, reduction of specific energy consumption is an important objective. This article provides a mathematic description of the two-phase flow motion at the outlet of the vertical acceleration tube of a jet mill with a plane grinding chamber of torus-shaped form. The part of the acceleration tube above the impact plate is essential for grinding, as the initial particle grind occurs at this very section, in the grind chamber. Moreover, the initial grind defines the size of particles, that are further reground at the mill chamber. As the result of theoretical calculations a formula, that enables to define the height of an acceleration tube from the baffle element at the specified velocity parameters of the two-phase flow. The article also contains the graph, that shows how particle velocity depends on the current (specific) height point (value) of the acceleration tube. This graph shows that particle size strongly affects the way they move in the grind chamber. Using the formula we can calculate the effective propulsion range of particles, depending on theirs’ size, by presuming they have the maximum velocity.
Patent•
02 Feb 2021
TL;DR: In this article, a modification method of inorganic filler is described, and the method comprises: crushing inorganic fillers to achieve a certain mesh number through a mechanical crusher, carrying out ultrafine crushing through a jet mill to obtain ultrafine powder, and introducing the treated powder into a powder modifier, adding an activator and a coupling agent.
Abstract: The invention provides a modification method of inorganic filler, and the method comprises: crushing inorganic filler to achieve a certain mesh number through a mechanical crusher, carrying out ultrafine crushing through a jet mill to obtain ultrafine powder, carrying out high temperature treatment on the ultrafine powder, introducing the treated powder into a powder modifier, adding an activatorand a coupling agent, and carrying out surface modification to obtain the modified inorganic filler. The inorganic filler obtained by the method disclosed by the invention is ultrafine in particle size, uniform in distribution, good in surface modification effect, high in process equipment maturity and easy to industrialize, and the product can be used as a reinforcing filler for a silicone rubberproduct.