Fluidized Bed Jet Mill Research Articles

Designing Functional Fruit-Based Recovery Drinks in Powder Form That Contain Electrolytes, Peptides, Carbohydrates and Prebiotic Fiber Taking into Account Each Component's Osmolality.

High levels of osmolalities have been found in manufactured carbohydrate-based functional drinks that occasionally include added protein; however, fruit components rich in bioactive ingredients have been absent. It has proved difficult to obtain recovery drinks based on natural fruit components that deliver calories and nutrients to the body whilst simultaneously ensuring that the body is adequately hydrated after physical exertion; the problem being that it is difficult to ensure the drinks’ stability at low pH levels and maintain an appropriate sensory quality. This study aims to develop drinks based on natural fruit components that contain added electrolytes, carbohydrates, prebiotic fiber and protein; an improved water and electrolyte balance; the calories needed after intense physical exertion; a high content of nutrients; and a favorable sensory quality. Furthermore, the relationships between regressive osmolalities of beverage components are herein investigated. The study materials were raspberry powders (prepared via fluidized-bed jet milling, drying, freeze-drying and spray-drying) as well as citrated sodium, potassium, magnesium salts, isomaltulose, hydrolyzed collagen, whey protein isolate and prebiotic fiber. The drinks’ polyphenols and antioxidant properties were measured spectrophotometrically, whilst vitamin C content was determined using high-pressure liquid chromatography. The sensory qualities of each drink were assessed according to a scaling method. Six test versions of recovery drinks were prepared in which osmolalities ranged from 388 to 607 mOsm/kg water, total polyphenol content was 27–49 mg GAE/100 mL and vitamin C level was 8.1–20.6 mg/100 mL, following compositions defined by the study results. It is thus possible to obtain fruit-based recovery drinks of the recommended osmolality that contain added protein, prebiotics and fiber, as well as defined amounts of electrolytes and carbohydrates. All drinks were found to have a satisfactorily sensory quality. The design of appropriate recovery drink compositions was also greatly helped by investigating the relationships among the regressive osmolalities of beverage components (i.e., electrolytes, carbohydrates, fruit powders and protein).

Understanding the changes in particle size, structure, and functional properties of waxy maize starch after jet‐milling treatments

AbstractWaxy maize starch was subjected to fluidized bed jet milling treatments at classifier frequencies of 2,400, 3,000, and 3,600 rpm. Changes in the structure and physicochemical properties of waxy maize starch after jet milling were investigated and compared with the untreated starch. With an increase in classifier frequency, the particle size of starch significantly (p < .05) decreased and showed bimodal distribution after jet milling. The microscopy analysis indicated that surface of starch granules became rough with irregular shapes after jet milling treatment compared to smooth and regular shape for the untreated starch. The birefringence and X‐ray diffraction analyses showed that the jet milling destroyed the crystalline areas and decreased crystallinity of the starch. The micronized starch samples showed significantly lower (p < .05) gelatinization temperature, enthalpy, and viscosity than those of the untreated starch. However, an increase in special surface area, water solubility, swelling power, and pasting stability was found after jet milling of the waxy maize starch. Additionally, light transparency of the starch increased as temperature increased but decreased with storage time. The observed results showed that modified starch can be produced by jet milling.

Assessment of Chokeberry Powders Quality Obtained Using an Innovative Fluidized-Bed Jet Milling and Drying Method with Pre-Drying Compared with Convection Drying

There is a need and great interest among food producers in obtaining powders from fruit and vegetables of both high nutritional value and sensory qualities superior to those hitherto obtained by convection drying (CD) and spray drying methods and cheaper to prepare than the sublimation method. This study is focused on whether powders can be obtained from fruit berries with a sticky structure, using the chokeberry (Aronia melanocarpa) as a test example, by a combined fluidized-bed jet milling and drying (FBJD) of pre-dried fruit by CD to an adequate water activity (aw). The pre-drying step reduced sticking between fruit particles during the simultaneous drying and grinding processes of the FBJD method in order to obtain powders of desired granulation. Three different pre-drying temperatures of 50, 60, and 70 °C were tested for levels of microorganisms in chokeberries at a water activity of 0.4. Vitamin C content and antioxidant properties were also examined along with polyphenol separation. Fruit pre-dried at 60–70 °C had significantly higher vitamin C and polyphenolic content and greater antioxidant properties than those pre-dried at 50 °C. Further studies were thus undertaken on powders pre-dried at 70 °C in which antioxidant properties, vitamin C, and polyphenols content were also compared with CD obtained powders. The FBJD method combined with CD pre-drying proved superior to just using the CD method, where powders had a greater preservation of vitamin C at 84% (CD powders 35%), a 12% higher total polyphenol content, and a 10% higher antioxidant activity. The test method also uses a much shorter drying time than the CD method, because the grinding of the hard-textured material takes only few minutes.

Fluidized Bed Jet Milling Process Optimized for Mass and Particle Size with a Fuzzy Logic Approach.

The milling process is a complex phenomenon dependent on various technological and material parameters. The development of a fluidized bed jet milling model is of high practical significance, since milling is utilized in many industries, and its complexity is still not sufficiently recognized. Therefore, this research aims to optimize fluidized bed jet milling with the use of fuzzy logic (FL) based approach as one of the primary artificial intelligence (AI) methods. The developed fuzzy logic model (FLMill) of the investigated process allows it to be described as a non-iterative procedure, over a wide range of operating conditions. Working air pressure, rotational speed of the classifier rotor, and time of conducting the test are considered as inputs, while mass and mean Sauter diameter of the product are defined as outputs. Several triangular and constant linguistic terms are used in the developed FLMill model, which was validated against the experimental data. The optimum working air pressure and the test’s conducting time are 500 kPa and 3000 s, respectively. The optimum rotational speed of the classifier is equal to 50 s−1, considering the mass of the grinding product, and 250 s−1 for the mean Sauter diameter of the product. Such operating parameters allow obtaining 243.3 g of grinding product with the mean Sauter diameter of 11 µm. The research proved that the use of fuzzy logic modeling as a computer-based technique of solving mechanical engineering problems allows effective optimization of the fluidized bed jet milling process.

Cryogenic grinding performance of scrap tire rubber by devulcanization treatment with ScCO2

The cryogenic grinding performance of scrap tire rubber modified by devulcanization treatment in supercritical carbon dioxide (ScCO2) was studied with a fluidized-bed jet mill. Scrap tire rubbers devulcanized with various concentrations of devulcanizing reagents were ground to analyze the effect of the degree of devulcanization on the particle size distribution of the ground product. Population balance modeling based on selection and breakage functions was adopted to explore the evolution rule of the particle sizes in the grinding process. The results of the cryogenic grinding experiment show that the devulcanization treatment can promote particle size reduction and lead to the transformation of the grinding mechanism from abrasion to cleavage or fracture. Furthermore, Kapur function fitted by the population balance modeling was proposed with a cubic polynomial, and the calculation results agreed well with the experimental data.

Investigating the Possibility of Fabricating Pr2Fe14B/α-Fe Composite Materials by Oxidation of the Pr–Fe–B Alloy in a Fluidized-Bed Jet Mill

The results of studying the possibility of fabricating the Pr2Fe14B/α-Fe composite materials by oxidation of the Pr–Fe–B alloy in a fluidized-bed jet mill are presented. It is shown that the use of the standard powder metallurgy technology supplemented by oxidation of the Pr–Fe–B alloy in a fluidized-bed jet mill for rare-earth magnetically hard materials (MHMs) makes it possible to fabricate Pr2Fe14B/α-Fe composites with high magnetic characteristics. It is established that, when fabricating finely dispersed powders according to the proposed technology in the argon medium containing 0.2 vol % oxygen, residual magnetic induction (Br) occurs with an insignificant drop in the coercive force (jHc). This effect causes a 5% increase in the maximal energy product (BH)max. The almost complete oxidation of the highly praseodymium phase PrxFe occurs with a further increase in the oxygen concentration, which leads to an abrupt drop in the coercive force and, consequently, a decrease in (BH)max. The particles of the α-Fe phase formed due to the oxidation of the magnetic material are formed at the boundaries between the grains of the Pr2Fe14B phase. Herewith, the highest magnetic characteristics are implemented if the α-Fe particles are separated from the grains of the main magnetic phase by thin interlayers of nonmagnetic phases, which makes it possible to hold a high level of jHc for sintered MHM samples. Herewith, the optimal thickness of the α-Fe layers is 0.2–0.3 μm. The α-Fe layers formed with an oxygen content of 0.3 vol % turned out considerably thicker (from 0.8 to 1.1 μm), which leads to an almost 10% decrease in the coercive force of the samples and 3–7% decrease in other magnetic parameters (Br, (BH)max). Thus, when controlling the oxygen content in the working medium of the jet mill, we can vary the thickness of the interlayer of the forming α-Fe phase in the Pr2Fe14B/α-Fe composite material and control its magnetic parameters.

An investigation on optimum grinding system and conditions for steel plant ARP by-product α-Fe2O3 for pigment industry

After some other processes, α-Fe2O3 red powder particles -by-product of regeneration of spent pickling liquor in ARP in iron and steel industry- should be ground up to pigment grade to convert it to a value added product, red iron oxide pigment. In this study, grinding tests on α-Fe2O3 red powder were performed using four different types of laboratory-scale mills, namely the vibrating cup mill, vertical ball mill, planetary ball mill, and fluidized bed jet mill. The particle structure of the α-Fe2O3 was investigated by SEM, while its chemical composition was determined by ICP-OES, density, LOI, humidity, Cl content etc. were determined by laboratory tests. Particle size distribution and surface area value of each ground sample was determined using the laser diffraction method. Targeted particle size distribution ranges could only be achieved with the jet mill. Other mills encountered caking and adhesion problem with α- Fe2O3. It was assessed that the adhesion to the inner walls of the grinding chamber and the caking effect were both caused by the humidity content of the material. The grinding yield of the material was found to increase with increased jet mill grinding air pressure (0.8, 3.2 and 7 bars).

Investigation of the possibility of Pr<sub>2</sub>Fe<sub>14</sub>B/α-Fe composite obtaining by Pr–Fe–B alloy oxidation in a fluidized bed jet mill

Investigation of the possibility of Pr<sub>2</sub>Fe<sub>14</sub>B/α-Fe composite obtaining by Pr–Fe–B alloy oxidation in a fluidized bed jet mill

MODELING AND CALCULATION OF GRINDING AND CLASSIFICATION OF MIXTURE OF DISSIMILAR COMPONENTS IN CLOSED MILLING CIRCUIT

It is shown that the developed earlier model of joint grinding of dissimilar particulate solids based on the discrete models of the Boltzmann equation does not take into account the possible size and density classification of particles and the operating of technological equipment in a closed milling circuit. It is substantiated that the problem of improving the efficiency of separation of mixture components, based on the analysis of their treatment in a closed milling circuit is an actual problem in the field. Theoretical investigations were based on the discrete models of the Boltzmann equation and the methods of their solution related to the technology of treatment of dissimilar components mixture. A special program for measurements and experimental data treatment obtained at the laboratory fluidized bed jet mill and the impact mill was developed for the experimental investigations. In the course of computational and experimental study a mathematical model of classification of dissimilar components was proposed and tested as well as the algorithm of its implementation into the general model of a closed milling circuit. The computational investigations were carried out to estimate the model sensitivity to the input parameters disturbance. The directions of improving the efficiency of the objective component separation in the closed milling circuit with the fluidized bed jet mill are found. The developed model the closed milling circuit for grinding dissimilar particulate solids can be used in engineering practice with acceptable accuracy. It can be used to estimate the possible enrichment of particulate solids mixtures and to define the optimal technological conditions of their separation with taking into account the limitations on the objective product impurity. The paths are outlined and the order of selection of the parameters of the grinding processes and the classification for effective separation of the components of the mixture are shown.

Comparison of quality and microstructure of chokeberry powders prepared by different drying methods, including innovative fluidised bed jet milling and drying

The study assessed the functional properties, microstructural features and sensory characteristics of chokeberry powders obtained by the new fluidised bed jet milling and drying method as compared to other drying methods such as freeze-drying, vacuum drying and convection drying. The new method was based on simultaneously drying and milling plant material which had been subjected to partial air drying at 70 °C prior to this treatment. The technique resulted in the production of good quality fruit powders with high vitamin C and polyphenolic content, as well as high antioxidant activity. Favourable physiochemical characteristics and sensory qualities were also observed together with low water activity. The new fluidized bed jet milling and drying therefore compared very favourably with freeze-drying, vacuum drying and convection drying when considering the content of bioactive substances, physiochemical features and the sensory quality of the prepared powders.

Properties and microstructure of blackcurrant powders prepared using a new method of fluidized-bed jet milling and drying versus other drying methods

ABSTRACTThis study compared the bioactive, physical and microstructural properties of blackcurrant powders prepared by an innovative fluidized-bed jet milling and drying method (FBJD) with those obtained by freeze drying (FD), convective drying (CD) and spray drying (SD). Bioactives such as vitamin C and anthocyanins were measured by HPLC, while antioxidant activity and total content of polyphenols were measured spectrophotometrically. A scanning electron microscope was used to establish the microstructure of both fresh fruits and powders. Water activity, water-holding capacity, water solubility index and pH were also determined. Retention of total polyphenols and vitamin C in FBJD powders was 88% and 79%, respectively, and 80% for both polyphenols and vitamin C in FD powders. Taking the above into account the FBJD method was found to be comparable to the FD method and compared favorably against the commonly used CD and SD methods.

Influence of Fluidized Bed Jet Milling on Structural and Functional Properties of Normal Maize Starch

Normal maize starch samples with moisture contents of 11.24%, 6.18%, and 1.5% are ground using a fluidized bed jet mill at classifier frequencies of 2400, 3000, 3600, and 4200 to produce micronized starch powder. The changes in structural and functional properties of the starch after jet milling process are studied. The particle size of starch significantly (p < 0.05) decreases after jet milling and as the classifier frequency increases. Also, the bulk and tap density decreases; while the specific surface area increases and the flowability of the milled samples becomes quite poor as the classifier frequency increases. The microscopy analysis shows that the jet milling destroys the crystalline areas and promotes amorphous areas of starch granules. The micronized starch samples show a significant (p < 0.05) increase in their water solubility, swelling power, water and fat holding capacities, and pasting temperature compared with native starch. However, a decrease in viscosity parameters of starch is found after jet milling and as classifier frequency increases. The initial moisture content of starch shows a slight effect on the functional properties of the micronized starch. The obtained results suggest that modified starch can be produced by fluidized bed jet milling.

A dry separation technique for improving the quality of coking coal middlings

ABSTRACTTo maximize the potential of China’s scarce coking coal resources, we studied quality improvement techniques for coal middlings using a self-designed fluidized bed jet milling–fineness classification system. The middlings were obtained from the Xiqu coal preparation plant of the Shanxi Coking Coal Group. The results of this study show that the maximum ash gradient occurs between the classifier-I products and the bag filter products. The particle size and mineral content of the classified products decreased with classification. The lowest recorded sulfur content in these products was 1.32%, and the desulfurization rate reached a maximum of 42.36%. Classifier-I had the highest classification accuracy (0.60), which corresponds to the highest recorded value of the maximum ash gradient. The higher the classification accuracy, the better the separation effect. The cyclone process yielded improved products with high yields. Range and variance analyses of orthogonal tests revealed that both the rotation speed of classifier-II and the crushing pressure significantly affected the ash content of the cyclone products. The influence of the various process parameters on the yield of the cyclone products was insignificant. Using the jet milling–fineness classification system, we classified products by ash content, sulfur content, particle size, and separation accuracy cascade change, enabling the quality improvement and classification of coal products.

NUMERICAL AND EXPERIMENTAL STUDY OF MIXTURE GRINDING OF MATERIALS WITH DIFFERENT STRENGTHS

At joint grinding of components with different strength the particles of more strong material are of larger size than the particles of less strong material. The size classification of such mixture allows enriching the objective component in the end product. The scientifically grounded choice of technological conditions for effective separation of a mixture of materials of different strength is an actual problem for chemical and other industries. The computational research was done using the conception of chemical processes modeling based on the discrete analogues of the Boltzmann equation. A special program for experimentations and experimental data treatment obtained at a lab-scale fluidized bed jet mill was developed. A model to describe the grinding kinetics for each component of a mixture was developed. It allows estimating the efficiency of enrichment of the end product by the objective component. A method to solve the equations of the selective model of grinding and the computer algorithm for its realization was developed as well. The experimental data on grinding of binary mixture of components at their different content in the fluidized bed jet mill hold-up were obtained. These data were used to identify the model with respect to the parameters that characterized the grindability of each component. The model adequacy was checked using the data on joint grinding of mixtures with different content of components. These data were not used for the model identification. Comparison of calculated and experimental data showed the model adequacy and possibility of its usage to estimate the efficiency of components separation. The investigation allowed generalizing the conceptions of chemical processes modeling based on the discrete analogues of the Boltzmann equation to the case of selective grinding of a mixture of components with different strength. The computational analysis showed that the model allowed describing the process with acceptable for engineering practice accuracy, practical estimating the possibility of components enrichment and defining the optimal technological conditions for their separation.Forcitation:Zhukov V.P., Osipov D.А., Otwinowski H., Urbaniak D. Numerical and experimental study of mixture grinding of materials with different strengths. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 6. P. 109-115.

Particle size distribution control and related properties improvements of tungsten powders by fluidized bed jet milling

Fine grinding process of different particle size tungsten powders was carried out by fluidized bed jet milling. The results showed that the jet milling treatment caused deagglomeration of tungsten powders, which led to particles sufficient dispersion and narrow particle size distribution. Grinding gas pressure of 0.70Mpa made the particles achieve high speed which promoted the particles collision contributing to particle dispersion and shape modification. For tungsten powder with particle size of 3μmFSSS, a higher packing density with 5.54g/cm3 was obtained, compared with the 3.71g/cm3 of the original powder. For tungsten powder with particle size of 1μmFSSS, the big agglomerates disappeared and the particle size distribution become narrower, while small aggregates about 2–3μm still exist after the jet milling process. For tungsten powder with particle size of 5μm and 10μmFSSS, different medium diameter particle size and narrow particle size distribution of monodisperse tungsten powders can be produced by the optimized jet milling parameters. More important, the effective dispersion, favorable shape modification and precise classification have been achieved in the simple process.

Simulation of combined heterogeneous processes based on discrete models of the Boltzmann equation

A new approach to simulating combined heterogeneous processes of chemical technologies based on the Boltzmann kinetic equation has been proposed. Examples of using this approach to describe processes in a gas−solid heterogeneous system when combining processes of the movement, grinding, and classification of particles in a fluidized bed jet mill have been reported. The possibilities and advantages of applying discrete models of the Boltzmann equation to describe combined heterogeneous processes have been shown.

Нелинейная модель измельчения смеси разнопрочных компонентов в струйной мельнице кипящего слоя

Нелинейная модель измельчения смеси разнопрочных компонентов в струйной мельнице кипящего слоя

Batch grinding kinetics of scrap tire rubber particles in a fluidized-bed jet mill

Grinding plays an important role in achieving scrap tires recycling. The batch grinding kinetics of scrap tire rubber particles in a fluidized-bed jet mill was studied based on population balance modeling. The selection and breakage functions were obtained according to the first Kapur function. It is found that these two functions were affected by the operating parameters such as the inlet gas pressure, feed load and grinding temperature. The breakage behaviors of scrap tire rubber particles under different operating conditions in the jet mill were discussed. Furthermore, a cubic function was proposed to predict the relation between the Kapur function and the particle size. The model prediction agrees well with the experimental data obtained under various operational conditions.

Novel Surface Modification of ZnO Nanoparticles by Fluidized-Bed Jet Mill

Novel Surface Modification of ZnO Nanoparticles by Fluidized-Bed Jet Mill

Modeling the Multi-Stage Classification in a Fluidized Bed Jet Mill

The research and modeling the classification effects in a fluidized bed opposed jet mill are presented. Particle distribution is the result of the interaction between two stages of classification in this mill: gravity classification above the bed, and centrifugal classification in a mill classifier. The objective of the study is to develop a model of multi-stage classification and apply in to the process in question. The universal algorithm of constructing the matrix model of arbitrary complex classification circuit is proposed and the example of its application to modeling the classification in the mill is presented. The experimental identification of the model parameters was carried out.