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Ball Mills

The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Achim Stolle – 1st expert on this subject based on the ideXlab platform

  • influence of reaction parameters on the depolymerization of h2so4 impregnated cellulose in planetary Ball Mills
    Powder Technology, 2016
    Co-Authors: Robert Schmidt, Sindy Fuhrmann, Lothar Wondraczek, Achim Stolle

    Abstract:

    Abstract The depolymerization of acid-impregnated cellulose in planetary Ball Mills was investigated under the perspective of the influence of reaction parameters. Several process, technological and chemical parameters were examined. It was found that with a higher rotation frequency νrot, smaller milling Balls and a milling Ball filling degree ΦMB of approximately 0.3, the highest solubility could be reached and the milling time could be reduced. The use of milling vessels with larger diameter was beneficial. Variation of the milling Ball material showed huge influence and a linear correlation between solubility and density of the milling Ball material was observed. Kinetic investigations indicate that the degradation of the impregnated cellulose follows a first order model.

  • effect of reaction parameters on the synthesis of 5 arylidene barbituric acid derivatives in Ball Mills
    Organic Process Research & Development, 2015
    Co-Authors: Robert Schmidt, Arno Kwade, Christine Friederike Burmeister, Matej Balaž, Achim Stolle

    Abstract:

    The influence of crucial reaction parameters on Knoevenagel condensation in planetary Ball Mills was investigated. Rotation frequency (νrot), milling Ball diameter (dMB), milling Ball filling degree (ΦMB), and beaker size had obvious influences on yield. It was found that higher νrot, lower dMB, milling beakers with larger diameter, and a ΦMB of ∼0.3 are advantageous for the reaction. Furthermore, the influence of the type of mill was investigated, including reactions performed in different planetary and mixer Ball Mills, in a stirred media mill, and with a mortar mill. Comparisons with the other solvent-free synthetic routes showed that Ball milling is an effective way of performing the reaction with low energy intensity.

  • scale up of organic reactions in Ball Mills process intensification with regard to energy efficiency and economy of scale
    Faraday Discussions, 2014
    Co-Authors: Achim Stolle, Robert Schmidt, Katharina Jacob

    Abstract:

    The scale-up of the Knoevenagel-condensation between vanillin and barbituric acid carried out in planetary Ball Mills is investigated from an engineering perspective. Generally, the reaction proceeded in the solid state without intermediate melting and afforded selectively only one product. The reaction has been used as a model to analyze the influence and relationship of different parameters related to operation in planetary Ball Mills. From the viewpoint of technological parameters the milling Ball diameter, dMB, the filling degree with respect to the milling Balls’ packing, ΦMB,packing, and the filling degree of the substrates with respect to the void volume of the milling Balls’ packing, ΦGS, have been investigated at different reaction scales. It was found that milling Balls with small dMB lead to higher yields within shorter reaction time, treaction, or lower rotation frequency, rpm. Thus, the lower limit is set considering the technology which is available for the separation of the milling Balls from the product after the reaction. Regarding ΦMB,packing, results indicate that the optimal value is roughly 50% of the total milling beakers’ volume, VB,total, independent of the reaction scale or reaction conditions. Thus, 30% of VB,total are taken by the milling Balls. Increase of the initial batch sizes changes ΦGS significantly. However, within the investigated parameter range no negative influence on the yield was observed. Up to 50% of VB,total can be taken over by the substrates in addition to 30% for the total milling Ball volume. Scale-up factors of 15 and 11 were realized considering the amount of substrates and the reactor volume, respectively. Beside technological parameters, variables which influence the process itself, treaction and rpm, were investigated also. Variation of those allowed to fine-tune the reaction conditions in order to maximize the yield and minimize the energy intensity.

Arno Kwade – 2nd expert on this subject based on the ideXlab platform

  • dry grinding in planetary Ball Mills evaluation of a stressing model
    Advanced Powder Technology, 2018
    Co-Authors: Christine Friederike Burmeister, Sandra Breitungfaes, Larissa Titscher, Arno Kwade

    Abstract:

    Abstract Planetary Ball Mills at laboratory scale are widely used for grinding and alloying processes. However, in contrast to other mill types, no applicable mechanistic model exists to describe the stressing conditions and their effect on particle breakage, so that processes are empirically evaluated so far. Within this study, the stressing conditions are determined by simulations based on the discrete element method including the contact model of Hertz and Mindlin. The contact model parameters are carefully calibrated by a series of experiments, so that it is finally possible to validate the simulation results by comparison of measured and calculated power values. The correlation of stressing conditions and breakage rates of alumina powder demonstrates the effect of stressing on breakage kinetics and breakage mechanism. It allows calculating the active mass in dependence on process parameters by an extension of Schonert’s active mass model. Altogether, the presented stressing model features analytical functions for the mill-related stressing conditions and highlights the importance of stressing intensity as process determining parameter, which defines the required number of material-related stressing events and the specific energy.

  • effect of reaction parameters on the synthesis of 5 arylidene barbituric acid derivatives in Ball Mills
    Organic Process Research & Development, 2015
    Co-Authors: Robert Schmidt, Arno Kwade, Christine Friederike Burmeister, Matej Balaž, Achim Stolle

    Abstract:

    The influence of crucial reaction parameters on Knoevenagel condensation in planetary Ball Mills was investigated. Rotation frequency (νrot), milling Ball diameter (dMB), milling Ball filling degree (ΦMB), and beaker size had obvious influences on yield. It was found that higher νrot, lower dMB, milling beakers with larger diameter, and a ΦMB of ∼0.3 are advantageous for the reaction. Furthermore, the influence of the type of mill was investigated, including reactions performed in different planetary and mixer Ball Mills, in a stirred media mill, and with a mortar mill. Comparisons with the other solvent-free synthetic routes showed that Ball milling is an effective way of performing the reaction with low energy intensity.

  • experimental and computational investigation of knoevenagel condensation in planetary Ball Mills
    Chemical Engineering & Technology, 2014
    Co-Authors: Christine Friederike Burmeister, Achim Stolle, Robert Schmidt, Katharina Jacob, Sandra Breitungfaes, Arno Kwade

    Abstract:

    The influence of several process parameters like milling time, Ball-to-beaker volume ratio, diameter of milling Balls, and rotation frequency on the Knoevenagel condensation of vanillin and barbituric acid in planetary Ball Mills was investigated. These parameters determine the amount of energy provided for the reaction. Additionally, numerical simulations were carried out to describe the stress conditions in detail and to compute the drive power and energy transfer which cannot be measured directly. The mill and experimental parameters were modeled by the discrete element method with adequate coefficients of friction and restitution required to describe the powder behavior in the system. The coefficients were determined by correlation of experiments and simulations.

Robert Schmidt – 3rd expert on this subject based on the ideXlab platform

  • influence of reaction parameters on the depolymerization of h2so4 impregnated cellulose in planetary Ball Mills
    Powder Technology, 2016
    Co-Authors: Robert Schmidt, Sindy Fuhrmann, Lothar Wondraczek, Achim Stolle

    Abstract:

    Abstract The depolymerization of acid-impregnated cellulose in planetary Ball Mills was investigated under the perspective of the influence of reaction parameters. Several process, technological and chemical parameters were examined. It was found that with a higher rotation frequency νrot, smaller milling Balls and a milling Ball filling degree ΦMB of approximately 0.3, the highest solubility could be reached and the milling time could be reduced. The use of milling vessels with larger diameter was beneficial. Variation of the milling Ball material showed huge influence and a linear correlation between solubility and density of the milling Ball material was observed. Kinetic investigations indicate that the degradation of the impregnated cellulose follows a first order model.

  • effect of reaction parameters on the synthesis of 5 arylidene barbituric acid derivatives in Ball Mills
    Organic Process Research & Development, 2015
    Co-Authors: Robert Schmidt, Arno Kwade, Christine Friederike Burmeister, Matej Balaž, Achim Stolle

    Abstract:

    The influence of crucial reaction parameters on Knoevenagel condensation in planetary Ball Mills was investigated. Rotation frequency (νrot), milling Ball diameter (dMB), milling Ball filling degree (ΦMB), and beaker size had obvious influences on yield. It was found that higher νrot, lower dMB, milling beakers with larger diameter, and a ΦMB of ∼0.3 are advantageous for the reaction. Furthermore, the influence of the type of mill was investigated, including reactions performed in different planetary and mixer Ball Mills, in a stirred media mill, and with a mortar mill. Comparisons with the other solvent-free synthetic routes showed that Ball milling is an effective way of performing the reaction with low energy intensity.

  • scale up of organic reactions in Ball Mills process intensification with regard to energy efficiency and economy of scale
    Faraday Discussions, 2014
    Co-Authors: Achim Stolle, Robert Schmidt, Katharina Jacob

    Abstract:

    The scale-up of the Knoevenagel-condensation between vanillin and barbituric acid carried out in planetary Ball Mills is investigated from an engineering perspective. Generally, the reaction proceeded in the solid state without intermediate melting and afforded selectively only one product. The reaction has been used as a model to analyze the influence and relationship of different parameters related to operation in planetary Ball Mills. From the viewpoint of technological parameters the milling Ball diameter, dMB, the filling degree with respect to the milling Balls’ packing, ΦMB,packing, and the filling degree of the substrates with respect to the void volume of the milling Balls’ packing, ΦGS, have been investigated at different reaction scales. It was found that milling Balls with small dMB lead to higher yields within shorter reaction time, treaction, or lower rotation frequency, rpm. Thus, the lower limit is set considering the technology which is available for the separation of the milling Balls from the product after the reaction. Regarding ΦMB,packing, results indicate that the optimal value is roughly 50% of the total milling beakers’ volume, VB,total, independent of the reaction scale or reaction conditions. Thus, 30% of VB,total are taken by the milling Balls. Increase of the initial batch sizes changes ΦGS significantly. However, within the investigated parameter range no negative influence on the yield was observed. Up to 50% of VB,total can be taken over by the substrates in addition to 30% for the total milling Ball volume. Scale-up factors of 15 and 11 were realized considering the amount of substrates and the reactor volume, respectively. Beside technological parameters, variables which influence the process itself, treaction and rpm, were investigated also. Variation of those allowed to fine-tune the reaction conditions in order to maximize the yield and minimize the energy intensity.