Vibratory Disc Mill Research Articles

Milling amorphous FeSiB ribbons with vibratory ball and disc mills

Fe, Si and B powders, mixed with atomic composition Fe78Si9B13, are subjected after arc melting to a melt spinning process, which is optimized to obtain the greatest amount of amorphous ribbon. The amorphous ribbons are milled to powder form in a vibratory ball mill and a vibratory disc mill, taking care of maintaining the amorphous character. Ribbons and powders have been characterized by X-ray diffraction (XRD), laser diffraction, SEM and TEM microscopy, and differential scanning calorimetry (DSC). The amorphous character and particle size of the powders are characterized as a function of the mill charge and the milling time. It is shown that the use of the ball mill is appropriate for obtaining small quantities of amorphous or nanocrystalline powder, while the disc mill can process larger quantities of powder in a shorter time. The particle sizes obtained for milling times between 10 and 150 min range between 26 and 412 μm, ready for use in powder metallurgy processes.

Boosting the mechanocatalytic hydrolysis of cellulose by using a vibratory disc mill and clay minerals

Surface grinding using a vibratory disc mill boosts mechanocatalytic hydrolysis of cellulose. Water-soluble celluloses can be obtained with a high yield (>99%).

Prediction of average shape values of quartz particles by vibrating disc and ball milling using dynamic image analysis based on established time-dependent shape models

Although grinding kinetics has been the subject of many researches, there is no research examining the shape kinetics of particles ground by different mills using dynamic image analysis (DIA) in the literature. In this investigation, how the shapes of quartz particles change over time at two different size fractions in two different mills is modeled using the latest image analysis technique, since particle shape of mineral is important in flotation and hydraulic fracturing processes. Empirical time-dependent shape models based on the correlation between average circularity (Cav .) and bounding rectangle aspect ratio (BRARav.) parameters and grinding time for vibratory disc mill and ball milled particles are established with high R 2 values by different fitting. Furthermore, average shape values of particles ground by the mills depending on grinding time were predicted for two size fractions. It was found that, Cav. data can be better described by linear fitting equations, on the other hand BRARav. data can be better represented by power fitting equations. Since predicted and measured shape values were found close to each other, this approach provides useful information for estimating the milling time required to produce the particles by milling (with less energy and cost) appropriately for intended use.

Effect of mechanical activation on terbium dissolution from waste fluorescent powders

Rare earth elements (REEs), independently by the economic value, have a strategic importance and are involved, as critical materials, in the competition for their supply. An innovative process with the introduction of a preliminary physicochemical treatment was proposed. The mechanical activation of waste of fluorescent powders was performed by a vibratory disc mill at different experimental conditions to optimize the process. The mechanical forces induced to the powders cause crystal structure defects with a consequent increase of rare earths leachability. Factorial experimentations and analysis of variance were studied to determine the significant effects of the investigated factors (mechanical activation time, sulfuric acid concentration, pulp density and leaching temperature), especially for terbium dissolution. The preliminary activation allows to increase terbium dissolution of 35%. Then, according to the best conditions the subsequent operations of precipitation and calcination were performed obtaining a purity of 98.3% as rare earth oxides. Based on the experimental results, the flowsheet for rare earths recovery has been proposed and implemented by SuperPro Designer, a simulation software for process analysis and mass-energy balances. Finally, this paper reports a comparison between the present process with the mechanical pre-treatment and the alternative method based on thermal pre-treatment.

Comparative Analysis of the particle size on the porosity and the tensile properties of aluminium based metal matrix nano-composites

Milling a mixture of aluminium and manganese dioxide (MnO2) powders mixed in ratio of 1:7 by weight and the particle size has been varied by milling in a vibratory disc mill for 450, 600 and 750 min at 700 rpm to obtain Nano-sized alumina particles. Melting commercially pure aluminium followed by addition of different duration of milled powder mix while stirring the melt to synthesis nano-composites. The remaining aluminium powder will melt when the powder mixture will be added to molten Al-Mg alloy during composite processing. The remaining manganese oxide will also react with molten Al-Mg alloy during solidification processing of composite and generate alumina particles (in-situ). The reaction between manganese dioxide and molten alloy releases manganese for alloying with the molten Al-Mg alloy. To enhance wetting of resulting alumina particles by the melt, magnesium is added. It is observed that the porosity in the cast composite increases with increasing addition of particles milled for a given time and it is interesting to observe that for the same amount of addition, powders milled for higher milling time cause higher porosity. There is increasing strength and ductility compared with base alloy and composite prepared with 2wt% addition of different duration milled powder. The tensile properties for AM alloy shows yield strength of 75.9 MPa, tensile strength of 169.8 MPa and elongation of 11.12%. Tensile properties of different composites for addition of 2 wt% powder mix milled for 450, 600 and 750 min shows that 113.3 MPa, 91.8 MPa and 77.3 MPa of yield strength respectively, 250 MPa, 225.2 MPa and 216.8 MPa of tensile strength respectively and 25.65%, 25.68% and 23.91% of elongation respectively. For addition of 2 wt% powder mix milled for 450 min, there is improvement in yield strength by about 25%, tensile strength by about 35% and ductility by more than 120% in the nano-composite over those observed in the base alloy.

Measurement and evaluation of the grinding bodies’ motions in a vibratory disc mill filled with viscous fluids

The grinding bodies’ motions (grinding disc and grinding ring) in the mill chamber of a vibratory disc mill have been experimentally studied and subsequently evaluated as well as interpreted in detail.The horizontal movements have been recorded by means of a high-speed camera positioned perpendicularly above the mill and the vertical movements using a measurement sensor, which enables a sensitive measurement of the grinding disc’s variation in height. Simultaneously, the influence of the fluid viscosity and the fluid’s filling quantity on these movements have been determined. Both parameters distinctly influence the grinding bodies’ motions.An increasing viscosity shows initially no visible influence on the grinding bodies’ centre velocities. In the case high viscosities are reached, a significant decrease in the grinding bodies’ velocities appears due to the higher flow resistance or more specifically, higher fluid’s resistance or lower fluid’s flowability counteracting the motions. Due to increased sliding of the grinding bodies on a highly viscous fluid, an inversion of the grinding bodies’ direction of rotation develops additionally. A larger fluid’s filling quantity causes a reduction of the sliding friction between the elements, wherefore the grinding bodies’ velocities increase accordingly. The vertical analysis of the grinding disc’s variation in height clearly reveals that the grinding bodies slide on a viscous fluid during operational mode. At the same time, a small vertical gap between the respective grinding body and the mill chamber bottom appears.

The Effect of Temperature and Milling Process on Steel Scale Utilized as a Pigment for Ceramic Glaze.

This study is focused on the evaluation of the re-utilizability of scale originated during the steel casting and steel rolling processes as a pigment for glazes. Non-oiled scale with Fe3O4 as the major phase were used as a coloring component of transparent glaze matrix in: (i) as received state, (ii) thermally pre-treated at 700 and 900 °C, (iii) mechanically treated in planetary ball mill (60, 120 and 240 min) and (iv) mechanically treated in vibratory disc mill (60 and 120 min). Prepared glazes were applied on the surface of ceramic tiles prepared from a commercially available white ceramic slurry. The resulting tiles with given glaze were thermally treated at 800, 900 and 1060 °C. The pigments were characterized by X-ray powder diffraction method (XRD), X-ray fluorescence spectroscopy (XRF), granulometry (PSD), thermogravimetric analysis (TG) and differential thermal analysis (DTA), scanning electron microscopy (SEM/EDAX). The color of the samples was described by the coordinates L*a*b* from CIELAB color space. The results showed that the non-oiled scale is suitable as the pigment for ceramic glazes. Careful control of the scale treatment process (mechanical as well as thermal) together with the temperature of final glaze firing is necessary to obtain the glaze of desired color and quality.

Valorization of wood chips ash as an eco-friendly mineral admixture in mortar mix design

Wood chips ash coming from biomass heating plant is studied as an eco-friendly mineral admixture in mortar mix design. The raw material was mechanically activated by milling in a vibratory disc mill to a degree of fineness comparable to cement. For the mortars with ash dosage, basic physical, mechanical, hygric, and thermal properties is accessed. The mortars with partial Portland cement replacement with wood chips ash exhibited good functional properties for all studied ash dosages. With increasing amount of the ash used, the average pore diameter decreased due to the partial filler effect of WCHA in mortar mix. The strength activity index was very high for all studied mortars and gave evidence of the wood chips ash pozzolanity. The pozzolan effectiveness coefficient varied from 1.52 to 0.59, which proved the pozzolanity of the studied ash and synergic effects in the Portland cement-ash-water system. The results of leaching tests showed, the chlorides contained in ash were safely immobilized in the silicate matrix. The environmental evaluation revealed decrease in both carbon dioxide production and energy consumption by the use of wood chips ash in mortar mix. For the mortar with 20% substitution of Portland cement with wood chips ash, it represents 15% of CO2 and 16% of energy, as compared with the reference mortar mix. As the developed mortars possess good functional and environmental parameters the analyzed wood chips ash can be considered as an eco-efficient low-cost alternative to other pozzolans for production of blended binders.

Production of Multilayer Graphene in a Vibratory Disk Mill

AbstractOptimale Prozessbedingungen für das mikromechanische Abblättern von mehrschichtigem Graphen werden mit einer Scheibenschwingmühle realisiert, in der eine hochviskose Flüssigkeit bestehend aus Zucker und Graphitpartikeln zerkleinert wird. Die Bedingungen, bei denen die Scherkräfte im Prozess in der Scheibenschwingmühle entstehen, werden untersucht. Graphenblätter mit Schichtdicken von 2 – 10 Schichten werden gewonnen. Das erhaltene mehrschichtige Graphen kann bei der Herstellung von Lithium‐Ionen‐Akkumulatoren eingesetzt werden.

Pulverization of fibrous mineral wool waste

The total annual volume of mineral wool waste in the 27 European Union countries is expected to increase to 2.5 million tons per year by 2020. Unfortunately, mineral wool wastes are often considered unrecyclable, because their physical characteristics make them difficult to process. In many cases, the problem is caused by the material’s fibrousness. However, no studies have considered comminution methods for mineral wools. The objective of the present study is to investigate how various comminution mechanisms affect mineral wools’ physical characteristics, including appearance, bulk density, and fiber length and width. The study’s results show that compression-based methods (vibratory disc mill and hydraulic press) completely break down mineral wools’ fibrousness, whereas methods based on high cutting speeds affect bulk density and fiber length only moderately. In addition, the present study identifies a rapid method that can be used in a novel way to analyze a large number of mineral wool fibers.

Coal fly ash activation—Comparison of isothermal calorimetric data and mortar strength

The aim of this study was to determine the effect of mechano-chemical activation of fly ash on the early strength of Portland cement fly ash blends. Triethanolamine (TEA) and alkalis (NaOH or Na2SO4) were used as chemical activators. The mechanical treatment was carried out with a vibratory disc mill. The effect of activation was determined by the combination of isothermal heat conduction calorimetry over 48h in combination with measurements of compressive strength between 1 and 28 d. Direct comparison of the features of the heat flow curves with compressive strength evolution was enabled by applying a numerical quantification method to the calorimetric results. This procedure revealed a systematic increase in early strength produced by the combination of the fly ash activation methods (grinding, TEA, alkalis). In addition, the acceleration of the pozzolanic reaction by fly ash activation was verified by replacing the cement in a cement fly ash blend by the equivalent amount of portlandite.

The Exfoliation of Graphite Particles in the Vibratory Disk Mill

AbstractThe exfoliation of graphite particles during the treatment in the vibratory disk mill containing commercial sugar was investigated. During the collision of the grinding ring with the grinding chamber wall an intensive stressing of graphite takes place. After treatment in the mill, the resulting dark paste was solved in water and subjected to 10 min sonication. The suspension was centrifuged to remove the not exfoliated multilayered particles. Analysis of Raman spectra shows the presence of graphite sheets in suspension. The represented method of exfoliation is environmentally friendly and scalable.

Sub-oxide passivation of silicon nanoparticles through rapid mechanical attrition

Inks produced from the inclusion of silicon nanoparticles in a suitable polymer present the best opportunity for true printability of silicon with purely additive patterning under ambient conditions with no thermal post-processing. For large scale production of silicon nanoparticles, the most appropriate methods are vapor phase synthesis by pyrolysis of silane or the milling of bulk material. In this work, we compare low energy ball milling using zirconium ball with a rapid attrition of bulk silicon using a high-energy vibratory disk mill and show that the later process passivates the further growth of surface oxide on the nanoparticles. XPS results indicated a significant surface oxidation for silicon nanoparticles produced using low energy ball milling relative to the rapid attrition using the high-energy vibratory disk. HRTEM shows a pronounced surface oxide thickness on the nanoparticles produced via low energy ball mill. This surface oxide resulted in charge trapping and drastically effected the carrier transport of the compacted powder. The powder produced from the high-energy mill, in contrast, does not show a distinct surface oxide layer under HRTEM and the carrier transport was generally ohmic.

Effect of dispersed hydrophilic silicon dioxide nanoparticles on batch adsorption of benzoic acid from aqueous solution using modified natural vermiculite: An equilibrium study

The equilibrium adsorption of benzoic acid from an aqueous medium on a natural vermiculite-based adsorbent was studied in the presence and absence of hydrophilic silicon dioxide nanoparticles in batchwise mode. The adsorbent was prepared through grinding natural vermiculite in a laboratory vibratory disk mill and the surfactant modification of ground vermiculite by cetyltrimethylammonium bromide, subsequently. The equilibrium isotherm in the presence and absence of nanoparticles was experimentally obtained and the equilibrium data were fitted to the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models. The results indicated that the dispersion of silicon dioxide nanoparticles at optimum concentration in the liquid phase remarkably increases the removal efficiency. Furthermore, it yields a more favorable equilibrium isotherm and changes the compatibility of equilibrium data from the Langmuir and Temkin equations to just the Langmuir equation. A quadratic polynomial model predicting the equilibrium adsorbent capacity in the presence of nanoparticles as a function of the adsorbate and initial nanoparticle concentrations was successfully developed using the response surface methodology based on the rotatable central composite design. A desirability function was used in order to optimize the values of all variables, independent and dependent ones, simultaneously.

Utilization of Mineral Wools as Alkali-Activated Material Precursor.

Mineral wools are the most common insulation materials in buildings worldwide. However, mineral wool waste is often considered unrecyclable because of its fibrous nature and low density. In this paper, rock wool (RW) and glass wool (GW) were studied as alkali-activated material precursors without any additional co-binders. Both mineral wools were pulverized by a vibratory disc mill in order to remove the fibrous nature of the material. The pulverized mineral wools were then alkali-activated with a sodium aluminate solution. Compressive strengths of up to 30.0 MPa and 48.7 MPa were measured for RW and GW, respectively, with high flexural strengths measured for both (20.1 MPa for RW and 13.2 MPa for GW). The resulting alkali-activated matrix was a composite-type in which partly-dissolved fibers were dispersed. In addition to the amorphous material, sodium aluminate silicate hydroxide hydrate and magnesium aluminum hydroxide carbonate phases were identified in the alkali-activated RW samples. The only crystalline phase in the GW samples was sodium aluminum silicate. The results of this study show that mineral wool is a very promising raw material for alkali activation.

Effects of different mechanical treatments on structural changes of lignocellulosic waste biomass and subsequent Cu(II) removal kinetics

In this paper, the character of structural changes induced by different mechanical treatments to Prunus persica stones (PSs), and its subsequent effect on biosorption kinetics of Cu(II) were investigated. PSs were processed in vibratory disk mill (PS-V) and ultra-centrifugal mill (PS-C) and characterized by XRD, BET, SEM and FTIR spectroscopy. It was shown that PS-V was smaller and more reactive with less crystallinity index and hydrogen bond intensity compared to PS-C. In opposite, surface area of the PS-C was bigger than that of the PS-V. The total pore volume was about threefold, while the volume of micro pores was 9.29 times higher in PS-Cs than in PS-Vs.The kinetics of Cu(II) biosorption by both PSs was tested through various kinetic models: pseudo-first and pseudo-second order rate equations, Elovich equation, Boyd model, Weber–Morris and Urano–Tachikawa intraparticle diffusion model. For both sample types, Cu(II) biosorption occurred through combination of intraparticle and film diffusion mechanism, while kinetic results were best described by the pseudo-second order kinetic model. At the same time, the results indicated that together with kinetic rate the biosorption capacity of PS-C (21.20mgg−1) was higher than that of PS-V (16.30mgg−1).Mechanical activation like crushing and grinding will change material particle size, specific surface area and porosity, as well as its crystallinity. However, this paper elucidates that such physical structural changes will impact on heavy metal ions removal efficiency. This investigation suggests that the type of size reduction in lignocellulosic biosorbent preparation plays a very important role in overall biosorption performance, so it should be carefully considered every time when the mechanical treatment of material is necessary to be applied.

Preparation of in-situ Cu/NbC nanocomposite and its functionally graded behavior for electrical contact applications

Cu–15%NbC (volume fraction) powder was synthesized using the starting powders of Cu, Nb and graphite in a high energy vibratory disc mill for 7 h of milling under argon atmosphere. A composite sample and a Cu/NbC functionally graded material (FGM) sample were produced by using the two-step press and sintering at 900 °C for 1 h under vacuum. The microstructure and physical and mechanical properties of the specimens were investigated. The field emission scanning electron microscopy, energy dispersive X-ray and X-ray diffraction analysis confirmed the synthesis of the nanostructure matrix of 18–27 nm with the nanoparticles reinforcement of 42 nm after sintering, verifying the thermal stability of this composite at high temperature. The hardness of Cu–15%NbC was five times greater than that of the pure Cu specimen. The volume reduction of the sample after the wear test decreased in comparison with the pure Cu specimen. The electrical conductivity of the composite specimen decreased to 36.68% IACS. The FGM specimen exhibited high electrical conductivity corresponding to 75.83% IACS with the same hardness and wear properties as those of the composite sample on the composite surface. Thus, Cu/NbC FGM with good mechanical and electrical properties can be a good candidate for electrical contact applications.

Synthesis and Mechanical Properties of Cast Alumina Nano-particle Reinforced Metal Matrix Composites

The development of Lightweight metal matrix nano-composites (MMNCs) based on aluminium and magnesium has emerged as an important class of materials, finding increasing applications in automobile, aero-space and space industries, in their quest for achieving better fuel economy. The present study investigates the outcome of mechanical properties in a composite, reinforced nano particle. High energy milling using vibratory disc mill RS200, (Retsch, Germany) for 600minutes at 700rpm of manganese dioxide particles with excess of aluminium powder weight ratio of 1:7 ensures that nanoparticles generated, either of MnO2 or alumina, are mostly separate and surrounded by aluminium particles. The milled powder when added to aluminium alloy melt, the excess aluminium particles will melt leaving behind separate oxide nanoparticles without significant agglomeration. Micrographs observed under Transmission Electron Microscope (TEM) have revealed the presence of nano-sized γ-alumina particles as a consequence of milling. The amount of addition varies from 1 to 3wt % in steps of 1wt % of particles after drying is added to molten metal/alloy and the resulting slurry is cast in a mold to get cast nano-composite. The microstructure of cast composites when analyzed by TEM and FE-SEM, confirm separate occurrence of nano-particles without agglomeration and its mechanical properties show significant improvement in terms of yield strength, tensile strength and ductility.

Investigation of thermally induced processes in corundum refractory concretes with addition of fly ash

The effects that the fly ash addition has on the behavior of thermally resistant corundum concrete were discussed. Experimental program implied production of two refractory composites: ''referent'' concrete from 20 % of high-aluminate cement and 80 % of corundum aggre- gate, ''recycled'' concrete from 10 % of high-aluminate cement, 20 % of lignite coal ash, and 70 % of corundum aggregate. The fly ash was mechanically activated by a vibratory disk mill. In the concrete matrix, the ash had a role of cement partial replacement and microfiller. The mechanical and thermal properties of the concretes were studied at temperatures ranging from ambient to 1,400 C as adopted maximum. Mechanisms of thermally induced processes were observed by differential thermal analysis at 10, 20, and 30 C min -1 heating rates. Referent and recycled concretes showed differences in calculated acti- vation energies. The variations in refractory concretes performances were discussed with support of scanning electron microscope imagining and X-ray diffraction results. The recycled ash concrete exhibited properties that met the requirements for the castables, which proves it suitable for use in severe conditions at high temperature and highlights the reusing principle and possibility of cleaner and economically sustainable production.

Theoretical and experimental studies of benzoic acid batch adsorption dynamics using vermiculite-based adsorbent

In this article, the batch adsorption of benzoic acid from aqueous solution onto modified vermiculite was both experimentally and theoretically investigated. Mechanical modification of raw vermiculite was carried out by means of a laboratory vibratory disk mill. In addition, an organic modification was performed by cetyltrimethylammonium bromide. A set of experiments were conducted in order to optimize the adsorbent dosage, initial pH value and contact time and to evaluate the batch kinetics and the equilibrium isotherm. The Freundlich and the Toth isotherms best fitted our experimental data. A mathematical model was developed for the investigation of the adsorptive dynamic characteristics, thereby estimating the pore diffusivity based on the experimental results. The model showed a good agreement with the experiments and the effective diffusivity, the model adjustment parameter, was estimated as 0.33×10−9m2s−1.