Marcela Caixeta Machado - Academia.edu (original) (raw)

Papers by Marcela Caixeta Machado

Research paper thumbnail of Hydrodynamic behavior of Quinoa seeds in a rotary drum using the discrete element method (DEM)

Research paper thumbnail of Dehydration of microalgae Spirulina platensis in a rotary drum with inert bed

Powder Technology, Jun 1, 2019

Research paper thumbnail of Determinação Experimental e Análise Da Influência Do Coeficiente De Restituição Como Parâmetro De Entrada Em Simulação Dem De Um Moinho De Bolas

Research paper thumbnail of Restitution coefficient in grinding process: experimental determination and numerical analysis using DEM

Brazilian Journal of Chemical Engineering, Apr 1, 2022

The DEM technique has been widely employed to study the mechanical behavior of granular systems i... more The DEM technique has been widely employed to study the mechanical behavior of granular systems in several engineering fields. However, this approach has some drawbacks, such as the need to specify the input parameters. This work aimed to measure experimentally the restitution coefficient (COR) of chrome steel balls and quartzite gravel by varying the particles sizes, the thickness of impact surface and the drop height. Afterwards, we analyzed how these measured restitution coefficient values influence on the grinding media dynamic inside a ball mill by DEM simulations. We observed a significant influence exerted by the variation of particle size and the surface thickness on COR. There was also a difference in the restitution coefficient values when the pairs particle–surface of different sizes were permuted. Furthermore, we quantify the effects of the different experimental COR values on number of collisions and energy of the collisions in a ball mill.

Research paper thumbnail of An experimental analysis of coffee beans dynamics in a rotary drum

Canadian Journal of Chemical Engineering, Aug 20, 2017

Brazil is the largest producer and exporter of coffee in the world, one of the main global commod... more Brazil is the largest producer and exporter of coffee in the world, one of the main global commodities. During the processing of coffee beans, rotary drums are used in the drying and roasting phases. This equipment is widely used in many industrial sectors. According to characteristics of the drum, particulate material, and operating conditions, different flow regimes may arise. Such regimes have a direct influence on the performance of these processes and therefore their characterization is of great importance. The present work developed an experimental study about the dynamics of coffee beans, under green and roasted conditions, in a rotary drum. Transitions between rolling, cascading, cataracting, and centrifuging regimes were evaluated, for both green and roasted coffee beans. For the centrifuging regime, a comparison between experimental critical rotation speeds and the ones obtained by correlations found in literature was performed. Additionally, a new expression to predict the centrifuging rotation speed was proposed by the authors. Further analyses regarding the rolling regime were also carried out. For this regime, velocity profiles of the particles were evaluated, as well as the thickness of the active layer for different filling degrees and drum rotation speeds. Great similarity was found between the behaviour of the active region for coffee beans before and after the roasting process.

Research paper thumbnail of Experimental and Numerical Study of Grinding Media Flow in a Ball Mill

Chemical Engineering & Technology, Aug 7, 2017

This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the final Version of Record (VOR). This work is currently citable by using the Digital Object Identifier (DOI) given below. The final VoR will be published online in Early View as soon as possible and may be different to this Accepted Article as a result of editing. Readers should obtain the final VoR from the journal website shown below when it is published to ensure accuracy of information. The authors are responsible for the content of this Accepted Article.

Research paper thumbnail of Boundary conditions effects on the particle dynamic flow in a rotary drum with a single flight

Powder Technology, Apr 1, 2017

This study presents an experimental and numerical investigation of the particle dynamic flow in a... more This study presents an experimental and numerical investigation of the particle dynamic flow in a rotary drum with one flight, under different boundary conditions. The Euler-Euler approach with the kinetic theory of granular flow was used for all CFD simulations. The influence of different specularity coefficient values and no-slip boundary condition was assessed varying the particle-particle restitution coefficient and the rotational speeds. The particle-particle restitution coefficient of glass beads was experimentally measured and the effect of this parameter on the particle dynamics was also investigated. A highspeed video camera was used to measure the flight unloading profile and the bed height of particles in rolling regime at the drum bottom. Quantitative and qualitative analysis were performed in order to compare the simulated results with the experimental data, and then to determine the appropriate parameters to represent the real particle flow. It was observed that the specularity coefficient value of 0.5 and the restitution coefficient of 0.9 represented well the particle flow behavior in the flight at the rolling regime for the different rotational speeds analyzed.

Research paper thumbnail of Investigação Experimental e Numérica Do Coeficiente De Atrito Estático De Esferas De Moagem e Rochas

Research paper thumbnail of Restitution coefficient in grinding process: experimental determination and numerical analysis using DEM

Brazilian Journal of Chemical Engineering, 2022

The DEM technique has been widely employed to study the mechanical behavior of granular systems i... more The DEM technique has been widely employed to study the mechanical behavior of granular systems in several engineering fields. However, this approach has some drawbacks, such as the need to specify the input parameters. This work aimed to measure experimentally the restitution coefficient (COR) of chrome steel balls and quartzite gravel by varying the particles sizes, the thickness of impact surface and the drop height. Afterwards, we analyzed how these measured restitution coefficient values influence on the grinding media dynamic inside a ball mill by DEM simulations. We observed a significant influence exerted by the variation of particle size and the surface thickness on COR. There was also a difference in the restitution coefficient values when the pairs particle–surface of different sizes were permuted. Furthermore, we quantify the effects of the different experimental COR values on number of collisions and energy of the collisions in a ball mill.

Research paper thumbnail of A fluid dynamic study of the active phase behavior in a rotary drum with flights of two and three segments

Powder Technology

Abstract In the rotary dryers with flights, the drying occurs mainly in the active region where t... more Abstract In the rotary dryers with flights, the drying occurs mainly in the active region where the material comes into direct contact with the air stream. The design of these flights is a complex task and studies are necessary to gain an in-depth understanding of the particle dynamics. This work aims to investigate the effects caused by angulations in flights of two and three segments on the particle dynamics, especially in the active region. The prediction of the solids flow was investigated by simulation using a Discrete Element Method (DEM) approach in an open-source software LIGGGHTS®. The simulated results were compared with experimental data using glass beads, with the rotary drum operating with 12 flights. The active region characteristics were analyzed using the responses variables: mass of solids in active phase, percentage of active region area occupied by the particles and the dispersion of the particles in the active region.

Research paper thumbnail of The role of boundary conditions on the dynamics of green coffee beans in a rotated dryer

Proceedings of 21th International Drying Symposium, Sep 11, 2018

Research paper thumbnail of Determinação Experimental e Análise Da Influência Do Coeficiente De Restituição Como Parâmetro De Entrada Em Simulação Dem De Um Moinho De Bolas

Blucher Chemical Engineering Proceedings

Research paper thumbnail of Dehydration of microalgae Spirulina platensis in a rotary drum with inert bed

Powder Technology

Abstract Among the various species of microalgae, Spirulina platensis has recently attracted atte... more Abstract Among the various species of microalgae, Spirulina platensis has recently attracted attention from food and pharmaceutical industries due to its high contents of protein and bioactive compounds. Due to its high moisture content, a major challenge in the use of this microalga is its perishability. In this work, we investigated the use of a non-conventional rotary dryer (with an inert bed) for drying microalga Spirulina platensis. We quantified the effects of air temperature, feed rate, rotation speed, and filling degree of the inert particles on process performance. We then performed an optimization study using the Differential Evolution algorithm to identify the operating conditions that maximize process yield. We also performed a DEM simulation to gain a better understanding of the fluid dynamics. The results prove that this non-conventional system offers an interesting alternative for expanding use of this biomass, when performed under appropriate operating conditions.

Research paper thumbnail of Investigação Experimental e Numérica Do Coeficiente De Atrito Estático De Esferas De Moagem e Rochas

Blucher Chemical Engineering Proceedings

Research paper thumbnail of Avaliação Experimental e Numérica Da Dinamica De Particulas Em Tambor Rotatorio Operando Em Regime De Rolamento

Blucher Chemical Engineering Proceedings

RESUMO-Técnicas de simulação de escoamento granular são importantes ferramentas utilizadas em est... more RESUMO-Técnicas de simulação de escoamento granular são importantes ferramentas utilizadas em estudos envolvendo a dinâmica de partículas e segregação no interior de tambores rotatório. Neste trabalho foi aplicado a abordagem Lagrangeana para o estudo da dinâmica de partículas e da segregação em um tambor rotatório, a fim de comparar com os resultados, experimentais e de simulação usando a abordagem Euleriana, reportados na literatura. Os resultados da simulação apresentou uma boa concordância com as observações experimentais, tanto através dos perfis de velocidade, como pela cinética de segregação.

Research paper thumbnail of Boundary conditions effects on the particle dynamic flow in a rotary drum with a single flight

Powder Technology

Abstract This study presents an experimental and numerical investigation of the particle dynamic ... more Abstract This study presents an experimental and numerical investigation of the particle dynamic flow in a rotary drum with one flight, under different boundary conditions. The Euler-Euler approach with the kinetic theory of granular flow was used for all CFD simulations. The influence of different specularity coefficient values and no-slip boundary condition was assessed varying the particle-particle restitution coefficient and the rotational speeds. The particle-particle restitution coefficient of glass beads was experimentally measured and the effect of this parameter on the particle dynamics was also investigated. A high-speed video camera was used to measure the flight unloading profile and the bed height of particles in rolling regime at the drum bottom. Quantitative and qualitative analysis were performed in order to compare the simulated results with the experimental data, and then to determine the appropriate parameters to represent the real particle flow. It was observed that the specularity coefficient value of 0.5 and the restitution coefficient of 0.9 represented well the particle flow behavior in the flight at the rolling regime for the different rotational speeds analyzed.

Research paper thumbnail of Experimental Study of Charge Motion in a Tumbling Ball Mill

Materials Science Forum

Tumbling ball mills are a common comminution device in the mineral industry processing, wherein t... more Tumbling ball mills are a common comminution device in the mineral industry processing, wherein the particle size reduction is performed by action of the grinding media. Different forms of transverse motion in a rotating cylinder have been studied by many researchers. The aim of this paper was to study the transitional phenomena between cascading, cataracting and centrifuging motion. In order to observe these transitions, experiments were carried out in a tumbling mill of 300 mm diameter, and three sizes of chrome steel balls were used as grinding media. Each size of ball was employed in three different lengths of the mill with the purpose to investigate the end-walls effect in the behavior ball charge. The image analysis technique was employed to identify the transition regions. A high-speed camera with maximum speed of 2000 frames/s was used to record images. Experimental data showed it was not found the end-wall effects on the transitional behavior, and this effect can be assesse...

Research paper thumbnail of Análise Experimental e Numérica Do Coeficiente De Restituição Em Simulações CFD Dos Regimes De Escoamento Em Um Moinho De Bolas

Blucher Chemical Engineering Proceedings

Research paper thumbnail of An experimental analysis of coffee beans dynamics in a rotary drum

The Canadian Journal of Chemical Engineering

Brazil is the largest producer and exporter of coffee in the world, one of the main global commod... more Brazil is the largest producer and exporter of coffee in the world, one of the main global commodities. During the processing of coffee beans, rotary drums are used in the drying and roasting phases. This equipment is widely used in many industrial sectors. According to characteristics of the drum, particulate material, and operating conditions, different flow regimes may arise. Such regimes have a direct influence on the performance of these processes and therefore their characterization is of great importance. The present work developed an experimental study about the dynamics of coffee beans, under green and roasted conditions, in a rotary drum. Transitions between rolling, cascading, cataracting, and centrifuging regimes were evaluated, for both green and roasted coffee beans. For the centrifuging regime, a comparison between experimental critical rotation speeds and the ones obtained by correlations found in literature was performed. Additionally, a new expression to predict the centrifuging rotation speed was proposed by the authors. Further analyses regarding the rolling regime were also carried out. For this regime, velocity profiles of the particles were evaluated, as well as the thickness of the active layer for different filling degrees and drum rotation speeds. Great similarity was found between the behaviour of the active region for coffee beans before and after the roasting process.

Research paper thumbnail of Experimental and Numerical Study of Grinding Media Flow in a Ball Mill

Chemical Engineering & Technology

This paper involves an experimental and numerical study on the grinding media dynamics inside a b... more This paper involves an experimental and numerical study on the grinding media dynamics inside a baffled ball mill under different solid flow regimes: cascading, cataracting and centrifuging. The Eulerian approach was used for all simulations and the boundary condition at the drum wall was investigated by means of the specularity coefficient parameter. This effort presents a meaningful temptation in representing the particle-wall interaction in a ball mill. The balls restitution coefficient was experimentally measured using a video camera, and its influence was evaluated by comparing the numerical and experimental outcome of flow patterns. The simulations results showed that the specularity and restitution coefficients effects at the drum wall were more evident at high rotation speeds.

Research paper thumbnail of Hydrodynamic behavior of Quinoa seeds in a rotary drum using the discrete element method (DEM)

Research paper thumbnail of Dehydration of microalgae Spirulina platensis in a rotary drum with inert bed

Powder Technology, Jun 1, 2019

Research paper thumbnail of Determinação Experimental e Análise Da Influência Do Coeficiente De Restituição Como Parâmetro De Entrada Em Simulação Dem De Um Moinho De Bolas

Research paper thumbnail of Restitution coefficient in grinding process: experimental determination and numerical analysis using DEM

Brazilian Journal of Chemical Engineering, Apr 1, 2022

The DEM technique has been widely employed to study the mechanical behavior of granular systems i... more The DEM technique has been widely employed to study the mechanical behavior of granular systems in several engineering fields. However, this approach has some drawbacks, such as the need to specify the input parameters. This work aimed to measure experimentally the restitution coefficient (COR) of chrome steel balls and quartzite gravel by varying the particles sizes, the thickness of impact surface and the drop height. Afterwards, we analyzed how these measured restitution coefficient values influence on the grinding media dynamic inside a ball mill by DEM simulations. We observed a significant influence exerted by the variation of particle size and the surface thickness on COR. There was also a difference in the restitution coefficient values when the pairs particle–surface of different sizes were permuted. Furthermore, we quantify the effects of the different experimental COR values on number of collisions and energy of the collisions in a ball mill.

Research paper thumbnail of An experimental analysis of coffee beans dynamics in a rotary drum

Canadian Journal of Chemical Engineering, Aug 20, 2017

Brazil is the largest producer and exporter of coffee in the world, one of the main global commod... more Brazil is the largest producer and exporter of coffee in the world, one of the main global commodities. During the processing of coffee beans, rotary drums are used in the drying and roasting phases. This equipment is widely used in many industrial sectors. According to characteristics of the drum, particulate material, and operating conditions, different flow regimes may arise. Such regimes have a direct influence on the performance of these processes and therefore their characterization is of great importance. The present work developed an experimental study about the dynamics of coffee beans, under green and roasted conditions, in a rotary drum. Transitions between rolling, cascading, cataracting, and centrifuging regimes were evaluated, for both green and roasted coffee beans. For the centrifuging regime, a comparison between experimental critical rotation speeds and the ones obtained by correlations found in literature was performed. Additionally, a new expression to predict the centrifuging rotation speed was proposed by the authors. Further analyses regarding the rolling regime were also carried out. For this regime, velocity profiles of the particles were evaluated, as well as the thickness of the active layer for different filling degrees and drum rotation speeds. Great similarity was found between the behaviour of the active region for coffee beans before and after the roasting process.

Research paper thumbnail of Experimental and Numerical Study of Grinding Media Flow in a Ball Mill

Chemical Engineering & Technology, Aug 7, 2017

This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the final Version of Record (VOR). This work is currently citable by using the Digital Object Identifier (DOI) given below. The final VoR will be published online in Early View as soon as possible and may be different to this Accepted Article as a result of editing. Readers should obtain the final VoR from the journal website shown below when it is published to ensure accuracy of information. The authors are responsible for the content of this Accepted Article.

Research paper thumbnail of Boundary conditions effects on the particle dynamic flow in a rotary drum with a single flight

Powder Technology, Apr 1, 2017

This study presents an experimental and numerical investigation of the particle dynamic flow in a... more This study presents an experimental and numerical investigation of the particle dynamic flow in a rotary drum with one flight, under different boundary conditions. The Euler-Euler approach with the kinetic theory of granular flow was used for all CFD simulations. The influence of different specularity coefficient values and no-slip boundary condition was assessed varying the particle-particle restitution coefficient and the rotational speeds. The particle-particle restitution coefficient of glass beads was experimentally measured and the effect of this parameter on the particle dynamics was also investigated. A highspeed video camera was used to measure the flight unloading profile and the bed height of particles in rolling regime at the drum bottom. Quantitative and qualitative analysis were performed in order to compare the simulated results with the experimental data, and then to determine the appropriate parameters to represent the real particle flow. It was observed that the specularity coefficient value of 0.5 and the restitution coefficient of 0.9 represented well the particle flow behavior in the flight at the rolling regime for the different rotational speeds analyzed.

Research paper thumbnail of Investigação Experimental e Numérica Do Coeficiente De Atrito Estático De Esferas De Moagem e Rochas

Research paper thumbnail of Restitution coefficient in grinding process: experimental determination and numerical analysis using DEM

Brazilian Journal of Chemical Engineering, 2022

The DEM technique has been widely employed to study the mechanical behavior of granular systems i... more The DEM technique has been widely employed to study the mechanical behavior of granular systems in several engineering fields. However, this approach has some drawbacks, such as the need to specify the input parameters. This work aimed to measure experimentally the restitution coefficient (COR) of chrome steel balls and quartzite gravel by varying the particles sizes, the thickness of impact surface and the drop height. Afterwards, we analyzed how these measured restitution coefficient values influence on the grinding media dynamic inside a ball mill by DEM simulations. We observed a significant influence exerted by the variation of particle size and the surface thickness on COR. There was also a difference in the restitution coefficient values when the pairs particle–surface of different sizes were permuted. Furthermore, we quantify the effects of the different experimental COR values on number of collisions and energy of the collisions in a ball mill.

Research paper thumbnail of A fluid dynamic study of the active phase behavior in a rotary drum with flights of two and three segments

Powder Technology

Abstract In the rotary dryers with flights, the drying occurs mainly in the active region where t... more Abstract In the rotary dryers with flights, the drying occurs mainly in the active region where the material comes into direct contact with the air stream. The design of these flights is a complex task and studies are necessary to gain an in-depth understanding of the particle dynamics. This work aims to investigate the effects caused by angulations in flights of two and three segments on the particle dynamics, especially in the active region. The prediction of the solids flow was investigated by simulation using a Discrete Element Method (DEM) approach in an open-source software LIGGGHTS®. The simulated results were compared with experimental data using glass beads, with the rotary drum operating with 12 flights. The active region characteristics were analyzed using the responses variables: mass of solids in active phase, percentage of active region area occupied by the particles and the dispersion of the particles in the active region.

Research paper thumbnail of The role of boundary conditions on the dynamics of green coffee beans in a rotated dryer

Proceedings of 21th International Drying Symposium, Sep 11, 2018

Research paper thumbnail of Determinação Experimental e Análise Da Influência Do Coeficiente De Restituição Como Parâmetro De Entrada Em Simulação Dem De Um Moinho De Bolas

Blucher Chemical Engineering Proceedings

Research paper thumbnail of Dehydration of microalgae Spirulina platensis in a rotary drum with inert bed

Powder Technology

Abstract Among the various species of microalgae, Spirulina platensis has recently attracted atte... more Abstract Among the various species of microalgae, Spirulina platensis has recently attracted attention from food and pharmaceutical industries due to its high contents of protein and bioactive compounds. Due to its high moisture content, a major challenge in the use of this microalga is its perishability. In this work, we investigated the use of a non-conventional rotary dryer (with an inert bed) for drying microalga Spirulina platensis. We quantified the effects of air temperature, feed rate, rotation speed, and filling degree of the inert particles on process performance. We then performed an optimization study using the Differential Evolution algorithm to identify the operating conditions that maximize process yield. We also performed a DEM simulation to gain a better understanding of the fluid dynamics. The results prove that this non-conventional system offers an interesting alternative for expanding use of this biomass, when performed under appropriate operating conditions.

Research paper thumbnail of Investigação Experimental e Numérica Do Coeficiente De Atrito Estático De Esferas De Moagem e Rochas

Blucher Chemical Engineering Proceedings

Research paper thumbnail of Avaliação Experimental e Numérica Da Dinamica De Particulas Em Tambor Rotatorio Operando Em Regime De Rolamento

Blucher Chemical Engineering Proceedings

RESUMO-Técnicas de simulação de escoamento granular são importantes ferramentas utilizadas em est... more RESUMO-Técnicas de simulação de escoamento granular são importantes ferramentas utilizadas em estudos envolvendo a dinâmica de partículas e segregação no interior de tambores rotatório. Neste trabalho foi aplicado a abordagem Lagrangeana para o estudo da dinâmica de partículas e da segregação em um tambor rotatório, a fim de comparar com os resultados, experimentais e de simulação usando a abordagem Euleriana, reportados na literatura. Os resultados da simulação apresentou uma boa concordância com as observações experimentais, tanto através dos perfis de velocidade, como pela cinética de segregação.

Research paper thumbnail of Boundary conditions effects on the particle dynamic flow in a rotary drum with a single flight

Powder Technology

Abstract This study presents an experimental and numerical investigation of the particle dynamic ... more Abstract This study presents an experimental and numerical investigation of the particle dynamic flow in a rotary drum with one flight, under different boundary conditions. The Euler-Euler approach with the kinetic theory of granular flow was used for all CFD simulations. The influence of different specularity coefficient values and no-slip boundary condition was assessed varying the particle-particle restitution coefficient and the rotational speeds. The particle-particle restitution coefficient of glass beads was experimentally measured and the effect of this parameter on the particle dynamics was also investigated. A high-speed video camera was used to measure the flight unloading profile and the bed height of particles in rolling regime at the drum bottom. Quantitative and qualitative analysis were performed in order to compare the simulated results with the experimental data, and then to determine the appropriate parameters to represent the real particle flow. It was observed that the specularity coefficient value of 0.5 and the restitution coefficient of 0.9 represented well the particle flow behavior in the flight at the rolling regime for the different rotational speeds analyzed.

Research paper thumbnail of Experimental Study of Charge Motion in a Tumbling Ball Mill

Materials Science Forum

Tumbling ball mills are a common comminution device in the mineral industry processing, wherein t... more Tumbling ball mills are a common comminution device in the mineral industry processing, wherein the particle size reduction is performed by action of the grinding media. Different forms of transverse motion in a rotating cylinder have been studied by many researchers. The aim of this paper was to study the transitional phenomena between cascading, cataracting and centrifuging motion. In order to observe these transitions, experiments were carried out in a tumbling mill of 300 mm diameter, and three sizes of chrome steel balls were used as grinding media. Each size of ball was employed in three different lengths of the mill with the purpose to investigate the end-walls effect in the behavior ball charge. The image analysis technique was employed to identify the transition regions. A high-speed camera with maximum speed of 2000 frames/s was used to record images. Experimental data showed it was not found the end-wall effects on the transitional behavior, and this effect can be assesse...

Research paper thumbnail of Análise Experimental e Numérica Do Coeficiente De Restituição Em Simulações CFD Dos Regimes De Escoamento Em Um Moinho De Bolas

Blucher Chemical Engineering Proceedings

Research paper thumbnail of An experimental analysis of coffee beans dynamics in a rotary drum

The Canadian Journal of Chemical Engineering

Brazil is the largest producer and exporter of coffee in the world, one of the main global commod... more Brazil is the largest producer and exporter of coffee in the world, one of the main global commodities. During the processing of coffee beans, rotary drums are used in the drying and roasting phases. This equipment is widely used in many industrial sectors. According to characteristics of the drum, particulate material, and operating conditions, different flow regimes may arise. Such regimes have a direct influence on the performance of these processes and therefore their characterization is of great importance. The present work developed an experimental study about the dynamics of coffee beans, under green and roasted conditions, in a rotary drum. Transitions between rolling, cascading, cataracting, and centrifuging regimes were evaluated, for both green and roasted coffee beans. For the centrifuging regime, a comparison between experimental critical rotation speeds and the ones obtained by correlations found in literature was performed. Additionally, a new expression to predict the centrifuging rotation speed was proposed by the authors. Further analyses regarding the rolling regime were also carried out. For this regime, velocity profiles of the particles were evaluated, as well as the thickness of the active layer for different filling degrees and drum rotation speeds. Great similarity was found between the behaviour of the active region for coffee beans before and after the roasting process.

Research paper thumbnail of Experimental and Numerical Study of Grinding Media Flow in a Ball Mill

Chemical Engineering & Technology

This paper involves an experimental and numerical study on the grinding media dynamics inside a b... more This paper involves an experimental and numerical study on the grinding media dynamics inside a baffled ball mill under different solid flow regimes: cascading, cataracting and centrifuging. The Eulerian approach was used for all simulations and the boundary condition at the drum wall was investigated by means of the specularity coefficient parameter. This effort presents a meaningful temptation in representing the particle-wall interaction in a ball mill. The balls restitution coefficient was experimentally measured using a video camera, and its influence was evaluated by comparing the numerical and experimental outcome of flow patterns. The simulations results showed that the specularity and restitution coefficients effects at the drum wall were more evident at high rotation speeds.