Uniform Balls Research Articles

THE EFFECT OF DRUM SPEED ON TIME AND GRAIN SIZE RESULTS FROM THE MILLING PROCESS

Grinding/crushing is a process of reducing the size in a crushing plant to get the desired size. The coal ball mill technique is where the ball collides with the feed on the tube wall, thus cracks will form in the feed which will result in a smaller size. Limitation of the problem in this study is the effect of speed on time and grain size resulting from the milling process, the mass of the sample used is 500 grams with grain sizes that do not pass a 10 mesh sieve, there are three types of pulley variations, namely, pulleys of 2 inch, 4 inch. , and 20 inches with a ball as a control using 10 uniform balls with a diameter of 4.58 cm

High-Energy Ball Milling for High Productivity of Nanobiochar from Oil Palm Biomass

The current production method of nanobiochar (NBC), an emerging, environmentally friendly nanocarbon material, is tedious and lengthy. Therefore, in this study we aimed to improve the productivity of NBC via high-energy ball milling by manipulating the grinding media and processing time. The particle size distribution of the resulting NBC measured using dynamic light scattering showed that grinding media with steel balls of different sizes were more effective at producing NBC than small uniform steel balls, which failed to produce NBC even after 90 min of milling. Average NBC particles of around 95 nm were achieved after only 30 min of ball milling, and the size was further reduced to about 30 nm when the milling was prolonged to 150 min. Further prolonging the milling duration led to agglomeration, which increased the size of the biochar nanoparticles. The thermogravimetric analysis (TGA) data showed that the duration of milling and particle size did not cause noticeable differences in the thermal stability of the NBC. Based on the FTIR analysis, the chemical structure of the NBC was not affected by the ball milling. The results showed that 60 min of high-energy ball milling is sufficient to produce NBC particles of 75 nm, with a large surface area and high thermal stability. This could prove beneficial in a myriad of applications, ranging from agriculture to composite fabrication.

Extraction procedure optimization of the method for detecting ethylene oxide and 2-chloroethanol in sesame seed

This study describes modifications of the extraction procedure within the European Union Reference method for determination of ethylene oxide and 2-chloroethanol in sesame seed. The method suggests utilisation of uniform stainless steel balls in order to facilitate extraction in small seed samples. Experiment was conducted with combination of balls of different sizes and the extraction efficacy was assessed by measurement of 2-chloroethanol in sesame seed samples from the local market. Increased efficacy of 18.3% for ethylene oxide and 16.2% for 2-chloroethanolwas observed when the combination of two diameters of balls was used compared to samples extracted by the guidelines in original method and alternative approach with uniform balls of the lower diameter..

Based on the technology of electromagnetic force driving and differential pressure control for producing solder balls

Uniform solder balls are widely used in 3D Printing and electronic packaging. Therefore, it needs a simple method for producing uniform solder balls at a higher quality. In this article, a novel and simple method was presented to produce uniform solder balls by the technology of electromagnetic force driving and differential pressure control. The results indicated that the uniform solder balls of Sn-58Bi alloy could be produced by two different modes of differential pressure control. The solder balls with a spherical degree between 0 and 3% and diameter with a mean variation of 4% were produced at different diameter and reasonable test parameters.

Simulation of bench blasting considering fragmentation size distribution

Reasonable simulation of the bench blasting has great significance on designing of rock blasting, and the proper consideration of blasting fragmentation size has strong influence on the simulation accuracy. This paper presents a new approach based on the three dimension Distinct Element Code (3DEC) method (Itasca Consulting Group, Inc. 2003) to model the dynamic cracking and casting process of bench blasting with reasonable consideration of blasting fragmentation size. Firstly, an equivalent blasting load consisting of the stress wave pressure and the detonation gas pressure was introduced into the 3DEC model, and it was applied on the outer boundary of blast-induced crushed zone to guarantee the simulation efficiency. Then, the whole numerical model was divided into discrete blocks by several sets of artificial joints to enable the rock to crack, fragment and cast, and at last form a muck-pile, and the artificial joints were assigned with the same mechanical parameters to rock mass itself to avoid the impact of them on stress wave propagation. Different from general discrete schemes which discretize the model with uniform blocks or random balls, the discrete size adopted in this paper gradually increases with distance from the blast source according to the Harries' model (Harries, 1973). At last, the proposed method was examined and verified by simulation of a blasting crater comparing to the field experiment, and then applied to explore the casting process of bench blasting. The simulated muck-pile profile agrees well with the result predicted by the traditional ballistics theory. The simulation also indicates that the casting distance of bench blasting increases with the bench height (H), but decreases with the burden distance (W), while the height of muck-pile increases with both the W and H. So the muck-pile profile of bench blasting is more sensitive to the W than H after consideration of rock fragmentation size, and the optimization of blasting designs can be significantly enhanced by utilizing the full capabilities of this approach.

Friction and Wear Behaviors of Indirect Dental Restorative Composites

Under different simulated oral environments (distilled water, artificial saliva, and a cola soft drink) and with a small-amplitude reciprocating apparatus, the friction and wear behaviors of 5 types of indirect dental restorative composites relative to uniform Si3N4 balls were investigated. Test parameters were: normal load with 20 N, reciprocating amplitude (1,000 μm), and frequency (0.25 Hz). Tests lasting up to 5,000 cycles were conducted. The wear damage characteristics are discussed in detail based on an analysis of friction behaviors, SEM observations, and 2- and 3-D profile microscopy. The results indicated that the hybrid resin composites with high filler weight and well filler distributions, such as Filtek P60, possess better wear resistance than nano-filled composites, such as VITA ZETA and VITA LC, with relatively low filler weight. Artificial saliva and a cola soft drink could play important roles in lowering the friction coefficient and wear loss of dental composites. The cola soft drink displayed a better lubrication effect. The degree of sensitivity to changes in lubrication conditions varies with different dental composites. Abrasive wear is the main wear mechanism for the 5 composites, but brittle cracks and delamination are more common for VITA ZETA and VITA LC.

Experimental study of lean flammability limits of methane/hydrogen/air mixtures in tubes of different diameters

Lean limit flames in methane/hydrogen/air mixtures propagating in tubes of internal diameters (ID) of 6.0, 8.9, 12.3, 18.4, 25.2, 35.0, and 50.2 mm have been experimentally studied. The flames propagated upward from the open bottom end of the tube to the closed upper end. The content of hydrogen in the fuel gas has been varied in the range 0–40 mol%. Lean flammability limits have been determined; flame shapes recorded and the visible speed of flame propagation measured. Most of the observed limit flames in tubes with diameters in the range of 8.9–18.4 mm had enclosed shape, and could be characterized as distorted or spherical flame balls. The tendency was observed for mixtures with higher hydrogen content to form smaller size, more uniform flame balls in a wider range of tube diameters. At hydrogen content of 20% or more in the fuel gas, limit flames in largest diameters (35.0 mm and 50.2 mm ID) tubes had small, compared to the tube diameter, size and were “lens”-shaped. “Regular” open-front lean limit flames were observed only for the smallest diameters (6.0 mm and 8.9 mm) and largest diameters (35.0 and 50.2 mm ID), and only for methane/air and (90% CH 4 + 10% H 2)/air mixtures, except for 6 mm ID tube in which all limit flames had open front. In all experiments, except for the lean limit flames in methane/air and (90% CH 4 + 10% H 2)/air mixtures in the 8.9 mm ID tube, and all limit flames in 6.0 mm ID tube, visible flame speeds very weakly depended on the hydrogen content in the fuel gas and were close to- or below the theoretical estimate of the speed of a rising hot bubble. This observation suggests that the buoyancy is the major factor which determines the visible flame speed for studied limit flames, except that last mentioned. A decrease of the lean flammability limit value with decreasing the tube diameter was observed for methane/air and (90% CH 4 + 10% H 2)/air mixtures for tubes having internal diameters in the range of 18.4–50.2 mm. This effect has been attributed to the stronger combined effect of the preferential diffusion and flame stretch in narrower tubes for flames which resemble rising bubble.

Index test for the degradation potential of carbonate sands during hydraulic transportation

Carbonate sands undergo degradation when transported hydraulically from a dredging vessel to the reclamation site. Risks involved in the production of fines during hydraulic transport are a deterioration of the mechanical properties of the fill in certain areas of the reclamation area where these fines concentrate. In order to assess sand degradation in the concrete and road construction industry, the Micro-Deval test for fine aggregates was developed in France and Canada. During Micro-Deval testing, aggregates degrade when tumbled in a rotating steel drum with water and steel balls. In the Canadian standard, the steel charge is lower than in the French standard and balls have the diameter of the smallest balls used in the French test. During testing, the quantity of fines produced is measured. This makes the Micro-Deval test an option for assessing the degradation of sand during hydraulic transportation of slurries in the dredging industry. Three sands are tested: two shelly carbonate sands and one quartzic river sand for comparison. The carbonate sands were sampled on reclaimed land and had been subjected to hydraulic transportation in pipeline before artificial deposition. Due to differences in particle shape, the carbonate sands and the quartz sand have a different number of contacts with the steel charge in the drum of the Micro-Deval and are not exposed to the same degradation forces during testing. It was found that the quartzic sand suffers relatively much degradation as compared to the carbonate sands, despite its greater hardness and resistance to crushability. The French test appears to create turbulence that promotes floatation of the curved shells of the carbonate sands instead of shell grinding at the bottom of the drum by contact with the steel balls. Microscopic observations of sand samples before and after testing showed that the French Micro-Deval test is too destructive. The test leads to the fragmentation by impact of the quartz sands and the destruction of certain particle types that had survived hydraulic transportation. With respect to the Canadian test, microscopic examination of sand grains before and after testing shows there is still much fragmentation of quartz grains. A lower rotational speed combined with a limited steel charge made of uniform balls of a smaller diameter, reduces turbulence, shell floatability and last but not the least, impact forces. It produces the desired result: a high Micro-Deval loss for the carbonate sands in comparison to that for the quartz sands and a very limited fragmentation of the quartz grains. Once the slurry reaches its destination, the grain size distribution of the fines fraction will influence the mechanical behaviour of mixed sands. A procedure is proposed to measure the particle size distribution of the fines fraction produced during Micro-Deval testing. Field validation is needed to validate preliminary laboratory results.

Electrospray‐Assisted Fabrication of Uniform Photonic Balls

Photonic balls have been fabricated (see Figure) by field‐enhanced electrospray of an aqueous colloidal suspension. The polystyrene (PS) beads inside the suspension droplets self‐organize into opaline balls while the solvent evaporates. The opaline balls are used as templates for inverse opaline photonic balls, and both types exhibit varying reflection colors depending on the diameter of the beads and the reflective index contrast.

Generation of uniform photonic balls by template-assisted colloidal crystallization

Uniform assemblies of all-identical colloidal particles, so-called photonic balls, are produced by injecting an aqueous suspension of polymer latex spheres into a surfactant-laden oil phase at an oil/water junction of capillary tubes or soft-microfluidic devices. The size of these assemblies can be controlled by varying the injection pressure or particle concentration.

Two-dimensional granular flow in a vibrated small-angle funnel

We have studied the flow of a single layer of uniform balls in a small-angle funnel when it is vibrated parallel to the flow. Generally, we measured the flow rate as a function of a dimensionless acceleration Gamma. However, for sufficiently small outlet widths, the flow can jam so we also measured the elapsed times between balls and their correlations to study jam dynamics. In particular, we found that when the funnel angle beta was larger than approximately 4 degrees, a stable jam always formed for Gamma<1 and the flow stopped. For Gamma approximately 1-4, jams still occurred, but now they broke and reformed, although they could last approximately 100 s, resulting in long-time correlations in the flow. The elapsed time distributions in this case show distinct, possibly algebraic, tails. Beyond Gamma approximately 4, the flow no longer jammed and the flow rate became constant. The general behavior has been mapped out in a rough phase diagram.

Statistics of shock waves in a two-dimensional granular flow.

We have investigated the dynamics of shock waves in a single layer of uniform balls in a small-angle two-dimensional funnel. When the funnel half-angle 0 degrees < or approximately beta < or approximately 2 degrees, the flow is intermittent and kinematic shock waves are observed to propagate against the flow. We have used fast video equipment and image analysis methods to study the statistics of the shock waves. It is found that their speed and frequency increase with the distance from the outlet. In particular, the shock speed scales as the ratio of the local funnel width to the width of the funnel outlet. Various kinds of interactions between shock waves are observed, including repulsion. New shock waves are only created at those sites where a close-packed triangular packing of the monodisperse balls fits across the funnel.

Two-dimensional granular flow in a small-angle funnel.

We have investigated a granular flow consisting of a single layer of uniform balls in a two dimensional funnel. The qualitative behavior of the flow depends in a sensitive way on the geometry. For a particular configuration in which only the funnel opening angle \ensuremath{\beta} is varied, we find three regimes. When \ensuremath{\beta}g2\ifmmode^\circ\else\textdegree\fi{}, the flow is dense and steady, and the flow rate is determined by the geometry at the outlet. When 0.1\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\lesssim}\ensuremath{\beta}\ensuremath{\lesssim}1\ifmmode^\circ\else\textdegree\fi{}, the flow is intermittent, consisting of quasiperiodic kinematic waves, probably shock waves, propagating against the flow. The flow rate reaches its maximum in this regime. When \ensuremath{\beta}0.05\ifmmode^\circ\else\textdegree\fi{}, the waves become stationary, and the flow rate is now determined by the geometry at the inlet. We also measure the number density fluctuations of the flow and their power spectra. For all flows, the power spectra are white at low frequencies with structures at higher frequencies resulting from the kinematic waves and short-range correlations. \textcopyright{} 1996 The American Physical Society.

Microspheres for Metal Powders

RETURN TO ISSUEPREVNewsNEXTMicrospheres for Metal PowdersLinde makes uniform microscopic balls of various metals and alloysCite this: Chem. Eng. News 1960, 38, 30, 52–57Publication Date (Print):July 25, 1960Publication History Published online6 November 2010Published inissue 25 July 1960https://doi.org/10.1021/cen-v038n030.p052Copyright © 1960 AMERICAN CHEMICAL SOCIETYArticle Views9Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (958 KB) SUBJECTS:Granular materials,Metals Get e-Alerts

Differential packing as a possible display of bedding

ABSTRACT The possibility that bedding and cross-lamination can be displayed by only an alternation of packing patterns was demonstrated in the laboratory by an artificially deposited clastic rock. A model of a coarse sandstone built up of uniform wooden balls, thereby eliminating entirely differences in size, shape, and composition of the constituent particles and restricting the differentiating variable to packing, showed bedding. Although this arrangement has not been located in natural rocks, it may be found after appropriate search. Hope for its existence is strengthened by the fact that open and close packing within sands is well known.