Powder Flow Research Articles

The enzymatic modification of whey-proteins for spray drying encapsulation of Ginkgo-biloba extract

Ginkgo biloba extract (GBLE) contains many bioactives including flavonoids and terpene trilactones that play some pharmacological roles. These compounds are sensitive to operating conditions; so, encapsulation is a suitable approach to protect them. In this study, different carriers including maltodextrin (MD), and its combination with gum-Arabic (MD-GA), whey protein concentrate (MD-WPC), and whey-protein hydrolysate (MD-HWPC) were used to encapsulate GBLE. Powder production yield, physicochemical/functional characteristics, physical stability and flowability of particles were affected by the type and composition of carriers. FTIR results indicated the placement of phenolic compounds in the carrier matrix. The SEM images also showed the morphological changes of particles (especially the size, indentation and surface shrinkage) under the influence of various carriers. Microencapsulated powders formulated using MD-HWPC showed the highest values of TPC, DPPH, and ABTS and a lighter color which determined the suitability of this wall material (due to the improvement of surface activity and emulsifying properties of protein as a result of partial enzymatic hydrolysis) to protect the antioxidant properties of GBLE during spray-drying, improving the production yield and preserving physical and functional characteristics of the encapsulated powders.

Powder flowability characterisation at preheating temperature in additive manufacturing

ABSTRACT The powder spreading process is usually performed at preheating temperature in powder-bed-based additive manufacturing (AM). Thus, the powder flowability characterisation at preheating temperature is important for powder spreading processes. However, devices for traditional powder flowability characterising methods are mainly designed for specific conditions at room temperature and cannot consider the effect of temperature on powder flowability. In this work, an experimental platform with a heated rotating drum was set up and a high-speed camera was used to record powder avalanche processes in a heated rotating drum for the powder flowability characterisation at preheating temperature. Nylon and stainless steel powder flowability at different temperatures was assessed by the statistical analysis of avalanche angle, avalanche time, arithmetic mean deviation and surface linearity of powder surface profile. Four parameters provide a good characterisation of powder flowability. The results can provide guidance for the powder flowability characterisation method at preheating temperature in AM.

Assessment of Physicochemical Parameters and Contaminants in Herbal Dietary Supplements Used in the Treatment of Inflammatory Bowel Disease.

Inflammatory bowel disease is a complex disorder characterized by chronic gastrointestinal inflammation. Thus, patients prefer to use herbal dietary supplements containing turmeric, Indian frankincense, green chiretta, and black pepper in an attempt to cope better with their chronic condition. The dietary supplements' dosage forms and herbal ingredients were assessed in terms of the products' physicochemical parameters (weight uniformity, friability, disintegration, rupture test, tablet's breaking force, and powder flowability) in view of the USP-NF requirements. In addition, contaminants such as organic solvents and ethylene oxide were evaluated using gas chromatography. Assessment of gluten via an Enzyme-Linked Immunosorbent Assay was also performed. Most of the products met USP requirements. The high average weight of one multicomponent tablet sample with a high breaking force value can explain the observed negative results of the disintegration test. A total of 26% of samples tested positive for gluten, but the most alarming fact is that the ethylene oxide levels found in two samples were up to 30 times higher than the EU limit. Accordingly, dietary supplement quality control is of fundamental importance.

PhasicFlow: A parallel, multi-architecture open-source code for DEM simulations

PhasicFlow is an open-source code for DEM simulations developed in C++, licensed under GPL V-3.0 [www.github.com/PhasicFlow/phasicFlow]. It is parallelized based on shared-memory model and can be executed on multi-core CPUs or GPUs. The philosophy of its development is to provide an efficient, easy-to-use, and easy-to-extend tool for a wide range of hardware including cheap to high-end desktop computers. Here, the code structure, the most important features, its performance for simulating small to large problems (250,000 to 80,000,000 particles) on various hardware are presented. In all cases, the execution time varied linearly with number of particles that is ideal for DEM. The computation load per particle was almost constant for all problem sizes except for small simulations (higher). For CPU simulations, a good scaling was observed with number of cores, and scaling was closer to ideal state for larger simulations. The performance of PhasicFlow was compared with similar tools, wherever possible. It was shown that the performance of PhasicFlow is much higher than the similar tools in CPU execution mode and it is around 10–15% faster than similar tools in GPU execution mode. This new tool broadens the application of computer simulation to larger problems and allows researchers to perform DEM simulations on a wider range of hardware. Program summaryProgram title: PhasicFlowCPC Library link to program files:https://doi.org/10.17632/fs7w7jb8mr.1Developer's repository link:www.github.com/PhasicFlow/phasicFlowLicensing provisions: GNU General Public License 3Programming language: C++Nature of problem: The code covers the simulation of granular matter in powder, gas-solid and liquid-solid flows. The formulation is based on the soft-sphere discrete element method (DEM) which is a powerful tool for simulating solid powder flows. Solid particles are considered distinct bodies that may interact with solid surfaces, other particles and fluid around them.This method can be purely used for investigating various flow problems or can be coupled with proper fluid flow simulation code to be used in multiphase flow systems. The main goal here is to provide a powerful tool for researchers to perform large-scale powder and multiphase flows on cheaper and more accessible hardware.Solution method: The solution method is based on the high-order explicit integration of equations of motions for discrete particles over time to obtain their linear and rotational position and velocity. Triangulation is used for representing solid walls and various motion models are implemented, which cover a wide range of processing units in the real-life application. Particle-particle and particle-wall interactions are modeled using linear and non-linear models accompanied with friction models.The code is designed to be executed fast, to efficiently use computational resources, and to be easily understood, altered and extended for specific uses. It is multi-architecture and can be executed in parallel on both CPU and GPU, depending on the available hardware. It uses Kokkos as the backend code for managing memory resources and dispatching parallel work on computational resources. Accordingly, a single code can be compiled for various hardware types. The parallelization is performed on high-level and with negligible overhead costs, so the developers of the code are not facing hardware-specific programming models when parallelizing the computations workloads.Additional comments including restrictions and unusual features: The simulation setup in the code is based on human readable text-based files that are supplied by the user. To use the code, no knowledge of programming is required. The GitHub repository contains a wiki page that provides a full set of tutorials to show researchers how to simulate various granular flows. A step-by-step procedure for building the code is also provided in the repository that has been tested on various version of Ubuntu, including versions 18.04 LTS, 20.04 LTS and 22.04 LTS.

Effect of carrier gas type on feeding characteristics of powder supply system

The new powder engine is an efficient power system with powder fuel as propellant. Its excellent performance is inseparable from stable and efficient powder feeding assisted by carrier gas. In this paper, we investigate the effect of carrier gas type (air, N2, CO2 and He, gas viscosity: CO2<N2<air<He) on the powder feeding characteristics of the powder supply system. The experimental results show that the change in carrier gas types has an insignificant effect on the powder flow pattern, but greatly affects the powder mass flow rate, pressure distribution and gas velocity in the silo, which is owing to the difference in the gas viscosity. Moreover, the analysis of powder column stress state reveals that the powder axial stress is related to the gas phase pressure gradient in the powder column. Specifically, under the same differential pressure, the smaller the gas viscosity, the higher the permeability, the greater the gas phase pressure gradient, the greater the powder axial stress pressure transferred to the outlet, thus obtaining a higher mass flow rate. However, energy analysis indicates that the smaller the gas viscosity, the higher the energy consumption required to transport the same mass powder. We hope our findings can provide ideas and references for efficient powder feeding.

Comprehensive powder flow characterization with reduced testing

Powder flow is a critical attribute of pharmaceutical blends to ensure tablet weight uniformity and production of tablets with consistent and reproducible properties. This study aims at characterizing different powder blends with a number of different rheologic techniques, in order to understand how particles’ attributes and interaction between components within the formulation generate different responses when analysed by different rheological tests. Furthermore, this study intends on reducing the number of tests in early development phases, by selecting the ones that provide the best information about the flowability attributes of the pharmaceutical blends. This work considered two cohesive powders - spray-dried hydroxypropyl cellulose (SD HPMC) and micronized indomethacin (IND) – formulated with other four commonly used excipients [(lactose monohydrated (LAC), microcrystalline cellulose (MCC), magnesium stearate (MgSt) and colloidal silica (CS)]. The experimental results showed that powder flowability may be affected by materials particles’ size, bulk density, morphology, and interactions with lubricant. In detail, parameters, such as angle of repose (AoR), compressibility percentage (CPS), and flow function coefficient (ffc) have shown to be highly affected by the particle size of the materials present in the blends. On the other hand, the Specific Energy (SE) and the effective angle of internal friction (φe) showed to be more related with particle morphology and materials interaction with the lubricant. Since both ffc and φe parameters are generated from the yield locus test, data suggest that a number of different powder flow features may be understood only by applying this test, avoiding redundant powder flow characterization, as well as extensive time and material spent in early development formulation stages.

Modeling and comparison of the powder flow dynamics for tilted annular and discrete-outlet nozzles in laser directed energy deposition

The Laser Directed Energy Deposition (L-DED) process is gradually maturing as an Additive Manufacturing (AM) technique. It provides substantial advantages for the refurbishment, redesign or coating of high-value components, which in general, are also large in volume and mass. For such components, it becomes necessary the use of a positioner which keeps the nozzle in a normal orientation as it is displaced over the different components’ surfaces. There is little understanding on the implications of tilting the nozzle on the process efficiency, as well as on the impact of using different nozzle configurations. This work presents a detailed Computational Fluid Dynamics (CFD) analysis of the powder stream generated by two widely used types of powder-fed coaxial nozzles: annular and discrete three-outlet nozzle. For different cases of nozzle orientation, the effect of mass flow and volumetric gas flow on particle velocity and powder convergence, are analyzed. This is crucially contrasted when the two nozzle types are taken into account. Further to analyzing stream behavior, this work also presents process maps for predicting powder usage rates. It was found that the powder usage is significantly affected by the nozzle type, mass and gas setting. For instance, for the case of a narrow 1.0 mm–wide melt pool in a 90°tilt, the annular nozzle is able to achieve up to 75.0% of powder capture efficiency, whereas for the three-outlet nozzle, this usage drops to 36.0%.

Effect of glidant in the formulation of goat milk tablet

Milk is an essential part of children's diets and can help them grow and develop properly. Goat milk is an excellent source of nutrition, providing a number of important vitamins and minerals. Despite this, the consumption of milk decreases as children grow older, mainly due to the availability of alternative drinks and an aversion to its taste. Therefore, this study aims to develop goat milk in the form of tablets using direct compression methods. This study focuses on improving goat milk's flowability and compressibility by changing the talc amount as a glidant used in the formulation. Six formulations containing 2% to 12% talc were prepared, designated F1 through F6. The results showed that adding talc as the glidant component improved the flowability of the blended powder, with the highest flowability observed at 10% talc concentration in formulation F5. It improved the flowability from “very, very poor” to “passable”, as determined by the USP standard. However, the flowability drops with excess glidant concentration, which is 12%. This study highlights the importance of glidants in improving powder flowability and the need for using suitable concentrations to prevent negative effects on the product's quality. Thus, pure goat milk in the form of liquid can be replaced by goat milk tablets prepared by the direct compression method. The compressibility and flowability of the powder mixed with the goat milk formulation were successfully improved, with good tablet hardness, uniformity of weight and a low friability index.

Development and Evaluation of Multiscale Fiber-reinforced Composite Powders for Powder-bed Fusion Process

The development of multiscale fiber-reinforced composite powders is an effective way to improve the mechanical properties and functionality of additively manufactured parts. Herein, a novel thermally induced precipitation process is proposed for preparing multiscale fiber-reinforced powders. A systematic evaluation was conducted to explore the main factors influencing powder morphology, powder flow, and microstructure. In the powder-forming mechanism, the polymer matrix is coated on the microfiber, and a film of carbon nanotubes covers the powder surface, which is promoted by heterogeneous nucleation. The composite powders comprised polyamide 12, carbon fiber (CF), and carbon nanotubes, which have been successfully applied in powder bed fusion processes including selective laser sintering (SLS). Smooth flow and powder deposition were observed, and the composite components obtained via SLS were well-fabricated using the optimized process parameters. A CF loading ratio of up to 66.7 wt% and homogeneous fiber distribution within the matrix were successfully achieved.

EFFECT OF ALUMINIUM WASTE POWDER ON THE STRENGTH PROPERTIES OF CEMENT MORTAR

The cement is used as primary binding material in the field of civil engineering is undoubtedly at a higher level due to the increase in urbanization. Concrete, cement mortar, and other composite building materials are made from it. The substantial use of OPC in the field of construction industry has increased the production of CO2. This has huge negative impact on the environment and has encouraged everyone to explore and analyze practical advancement by substituting alternative waste products in concrete and mortar. Therefore, the objective of this study was to evaluate the strength performance of cement mortar containing Aluminium waste powder as a Cementitious Material. In this study, we have substituted the cement with different percentages i.e., 2.5% to 10% of Aluminium waste powder to obtain feasible mortar mix. The cubes of 50 mm size were cured for 3, 7, and 28 days, the properties of flowability, density, and compressive strength was studied. The results indicated that by increase in addition of Aluminum waste powder (AWP) flowability of mortar paste decreased, the water cement ratio was fixed as 0.50 for all type of mixes. The results indicated that the Density and Compressive Strength of Cubes cured in water, it was observed that as the % Addition of AWP increased the density and compressive strength of cubes cured were reduced. For Compressive Strength, it was found that at each designated day, the compressive strength of cubes up to 2.5% addition has given suitable value but intensely decreased at 10% addition. At 2.5% Addition Aluminium waste powder on 28th day test it was noticed that it has greater value of compressive strength for all % of addition.

Additive manufacturing of a high-performance aluminum alloy from cold mechanically derived non-spherical powder

Metal additive manufacturing provides a path to optimized component design with significant realized advantages in the medical and aerospace industries. Limitations to expansion to other industries, e.g. automotive, and to enabling supply chain relief is the limited number of materials available and the ability to produce material on demand. Current additive manufacturing powder feedstock is produced at large, remote atomization facilities with long lead times. Here we identify a new “on-demand” powder production technology, cold mechanically derived, able to produce non-spherical powder for additive manufacturing, with high efficiency, and wrought equivalent material properties. We analyze the powder flow characteristics and mechanical properties comparing typical gas atomized with the new process demonstrating wrought property equivalence despite power sourcing. This research will enable expansion of additional alloy systems as well as encourage the processing of non-spherical powders to expand the available supply base of new alloys for additive manufacturing.

Evaluation of Flowability and Floodability for Dynamic Powder Flow Based on Particle Characteristics

Evaluation of Flowability and Floodability for Dynamic Powder Flow Based on Particle Characteristics

Effective role of grinding aids in the dry grinding performance of calcite

Grinding aids are organic compounds that chemically attach to a sufficient amount of particle surfaces and prevent the formation of gravitational forces between particles. With the use of grinding aids in grinding, it is possible to increase the amount of production with the wanted product fineness and obtain a finer product with the identical amount of production. The usage of grinding aids prevents particle pelleting and leads to reduced energy consumption. The work aims to research the impacts of three pure grinding aids from different chemical classes on the dry grinding of calcite by the change in grinding time in a vertical stirred media mill. Concerning the results, this study has different aspects than many other studies. In the current study, the results were assessed with different findings: product particle size (d50), media coating, and energy consumption. Additionally, powder flowability and surface area were evaluated by different methods. The findings obtained from the experiments demonstrate that all grinding aids in small quantities remarkably had a positive effect on grinding performance of the ground products in comparison to grinding without additives. Moreover, a strong impact of certain grinding aids on the each findings were combined around summary a target diagram.

Evaluating gas-driven flow mechanics of non-spherical powders for directed energy deposition

The size and shape of metal powder particles play a central role in the performance and utility of directed energy deposition (DED) based metal additive manufacturing processes. Given their significant economic advantage, unconventional non-spherical metal powders have recently emerged as a potential, economically viable, alternative for use as DED feedstock. In this work, we investigate the mechanics of carrier-gas driven powder flows for non-spherical metal powders using coupled experiments and numerical simulations. The experiments are performed on a custom-built DED system that allows us to individually vary both gas and powder flows systematically. By suitably adjusting the flow conditions to ensure equal mass flow rates, we show that non-spherical powders compare favorably against gas atomized spherical particles vis-á-vis final concentration distribution and flow mechanics. The differences between these two types of powder particles are quantified with flat, angled and curved substrate geometries, allowing predictions for many practical deposition situations. The simulations use a two-way discrete phase model and predict best (perfectly elastic) and worst (perfectly inelastic) case concentrations on the substrate by varying the particle restitution coefficient. Our results suggest suitable process modifications (gas flow rate, feed rate, axis traverse speed) to facilitate the use of non-spherical powders alongside conventional spherical powders in DED processes.

Reviewing the Impact of Powder Cohesion on Continuous Direct Compression (CDC) Performance.

The pharmaceutical industry is undergoing a paradigm shift towards continuous processing from batch, where continuous direct compression (CDC) is considered to offer the most straightforward implementation amongst powder processes due to the relatively low number of unit operations or handling steps. Due to the nature of continuous processing, the bulk properties of the formulation will require sufficient flowability and tabletability in order to be processed and transported effectively to and from each unit operation. Powder cohesion presents one of the greatest obstacles to the CDC process as it inhibits powder flow. As a result, there have been many studies investigating potential manners in which to overcome the effects of cohesion with, to date, little consideration of how these controls may affect downstream unit operations. The aim of this literature review is to explore and consolidate this literature, considering the impact of powder cohesion and cohesion control measures on the three-unit operations of the CDC process (feeding, mixing, and tabletting). This review will also cover the consequences of implementing such control measures whilst highlighting subject matter which could be of value for future research to better understand how to manage cohesive powders for CDC manufacture.

Thermogravimetric behavior of mesoporous hydrated silica-alumina trihydrate hybrid powder synthesized by sol–gel/doping method

Thermal degradation of mesoporous hydrated silica (MHS), mesoporous silica (MS), and alumina trihydrate (ATH) hybrid systems for flame retardant materials was investigated. The hybrid powders (contains 64 wt% of ATH) were created by doping ATH particles into a silica sol using the typical sol–gel technique with rice husk as a silica precursor. MHS-ATH has 3% more water by weight, three times lower density (0.9 g/cm3), 37 times larger surface area (186.88 m2/g), and enhanced powder flowability as compared to standard ATH. Thermogravimetric analysis (TGA) study reveals that MHS-ATH has higher thermal stability than ATH, with more water released gradually over a wider temperature range, improving the flame retardancy effect. MHS was also compared with its dehydrated form (MS), but TGA studies suggest that MS-ATH has lower thermal stability due to the powder's tendency to absorb moisture.

Cold-model numerical study of raceway shape and size effect on gas and fines flow behaviour in packed bed between the raceway and cohesive zone

ABSTRACT Operational stability and productivity of an iron-making blast furnace relies on the permeability of the bed, which is adversely affected by the accumulation of unburnt coal and fine coke powder resulting from Pulverised Coal Injection (PCI) and coke degradation. Stable operation at a high PCI rate necessitates an understanding of gas-fine powder distribution, which is affected by the cohesive zone, and raceway shape and size. A computational study of a laterally injected gas-fine powder flow through a tuyere, into a packed bed is conducted in the presence of raceway and cohesive layers. An experimental correlation is used to predict the static holdup. The effect of operational parameters such as gas flow rate, particle and fine properties, and structural parameters such as cohesive zone configuration, porosity, and tuyere protrusion are analysed. Sensitivity analysis shows raceway shape, size, and interaction with the cohesive blocks affects the distribution and accumulation of fine powder.

Investigating the compressibility and flowability of cocoa powders: A solution for chocolate industry

AbstractThe flowability and compressibility properties were determined for two types of cocoa powders, which are used commercially in chocolate industries; alkalized and natural cocoa powders. Physical and flow properties have a very significant role in the flow behavior, which relates to the handling, transportation, and storage of bulk powders. Throughout the research, it was observed that the properties of both cocoa powders are similar. The objectives of this work are to compare the compressibility and flowability between alkalized and natural cocoa powders and to design the minimum opening size of hopper for mass flow based on their flow properties. Jenike's mathematical methodology is applied during the research for the design of conical hoppers for mass flow. Besides, powder flow analysis using powder flow analyzer is one of the testing methodologies in this research. In addition, direct shear box tests were performed with three different normal stresses. The alkalized cocoa powder needs 1.366 m in diameter for the opening of the hopper, while the natural cocoa powder needs 1.531 m. From the results of the study conducted, it was concluded that both cocoa powders are very cohesive and have poor flow properties. This research reveals that the physical and flow properties of two main types of cocoa powder contributed a lot to the process of hopper design, enhance process understanding, and also applicable for analyzing the powder behavior at any stage in industry.Practical applicationsCocoa powder is the essential ingredient of chocolate manufacturing and other food industry having a chocolate‐like flavor including beverages, biscuits, desserts, and so forth. In chocolate industry, the flow behavior of cocoa powders can affect manufacturing efficiency, which directly affects the production capacity and product quality in terms of its weight and content uniformity. In this study, the critical design parameters such as hopper angle and size of opening were determined to improve the flowability of cocoa powders when passes through hopper. The findings of the present study make it possible for an accurate estimation of a correct intersection with the hopper flow factor line and effective angle of internal friction (δ), extrapolating the powder flow function ff curve to obtain hopper opening size for each cocoa powder for better flowability.

Dry Electrode Manufacturing in a Calender: The Role of Powder Premixing for Electrode Quality and Electrochemical Performance

The dry manufacturing of battery electrodes has the potential to significantly reduce costs and the environmental impact of battery production but deteriorates the electrode quality due to drawbacks in the processability of the materials. By varying the mixing intensity of the powder mixtures, this work investigates the impact of blend homogeneity on the flow properties and the processability of the dry mixtures. Furthermore, the electrochemical performance of dry laminated electrodes made of LiNi0.6Mn0.2Co0.2O2 is investigated with respect to their initial mixture homogeneities and compared to slurry-based electrodes. An improvement of the powder flowability is observed for mixtures with a homogeneously distributed PVDF binder, which acts as a temporary lubricant in dry electrode manufacturing due to its ability to shear, resulting also in filament formation. Capacity and rate performance of electrodes made of homogeneous mixtures are the highest with 169 mAh/g at C/20 and 70 mAh/g at 3C compared to 169 and 49 mAh/g for the slurry-based electrodes, respectively. Cyclic voltammetry indicates lower overpotentials for incompletely homogenized electrodes due to the existence of carbon black aggregates that establish better long-range conductivity. Overall, electrodes from highly homogenized powders show the best electrochemical performance in terms of C-rate capability due to their favorable electrode thickness and porosity resulting from better processability in combination with a sufficiently distributed carbon binder domain.

Correction to: Effect of gas permeation and consolidation stress evolution on powder flow properties in the gas pressurization process

Correction to: Effect of gas permeation and consolidation stress evolution on powder flow properties in the gas pressurization process