Effect Of Ball Diameter Research Articles

Effect of Ball Diameter on Mechanical Alloying Process for the Production of Dispersion Strengthened Tungsten

Effect of Ball Diameter on Mechanical Alloying Process for the Production of Dispersion Strengthened Tungsten

The Effect of Ball Diameter on Performance of Wet Scrubber with PVC Balls-Mesh Packing Material

Toxic pollutants and harmful flue gases resulting from combustion of fossil fuels in several industries are adversely effecting human and his environment. Packed towers, especially with wire mesh type mist eliminator pads are widely used to entrap these flue gas emissions before they enter into the atmosphere. But clogging of pads during the operation became a big problem which needs replacement with new one every time. The present work motivation is to develop and test, a exhaust fume-wet scrubber with new (PVC) balls-mesh replacing traditional packing material in which the spherical surfaces are going to make only point contact between them. Water (PH Value = 8.7) and lime water (PH Value = 12.3) sprinkled finely in modified air cooler body with 72 nozzles of 1mm in diameter and re-circulated for 100 minutes to purify stationary four stroke diesel engine exhaust. The diameter of the balls used, are varied such as 10cm, 5cm and 2.5cms and drain water samples, for every 20 minutes are collected to check PH values.

Ultra fine grinding of silver plant tailings of refractory ore using vertical stirred media mill

Ultra fine grinding of the plant tailings of a refractory silver ore was studied using a laboratory type vertical stirred media mill. Preliminary tests confirmed that ultra fine grinding substantially improves the extraction of silver from the tailings in cyanide leaching (i.e. 36% Ag extraction rate from the as-received tailings with d80 of 100 μm, c.f. 84% extraction rate after ultra fine grinding of the tailings with d80 of 1.2 μm). In the ultra fine grinding tests, the effects of ball diameter (2–4.5 mm), stirring speed (200–800 r/min) and ball charge ratio (50%–80%) on the fineness of grind (d80, μm) were investigated through a Box–Behnken design. Increasing stirrer speed and ball charge ratio decreased fineness of grind while larger balls resulted in the coarser products. The tests demonstrated that a fineness of grind less than 5 μm can be achieved under suitable conditions. Analysis of stress intensity indicated an optimum range of stress intensity of (0.8–2)×10−3 N·m for all power inputs.

Thermoelectric Properties of Nanocrystalline PbTe Synthesized by Mechanical Alloying

In this work, nanocrystalline lead telluride powder was synthesized from high-purity elements by mechanical alloying by means of a planetary ball-milling procedure. The milling medium was tungsten carbide, and the diameter of the balls was varied in order to investigate the effect on the structural features of the material. Phase transformations and crystallite evolution during ball-milling were followed by powder x-ray diffraction (PXRD). The broadened PXRD peaks were analyzed with Voigt functions, revealing small crystalline size and stress introduced during the mechanical alloying process. Transmission electron microscopy (TEM) studies confirmed the material’s nanostructure, as well as the effect of ball diameter on the size of the crystals. Thermoelectric properties are discussed in terms of the Seebeck coefficient and the nominal carrier concentration, as determined by Hall-effect measurements. The enhancement of the Seebeck coefficient is reported to be higher compared with other PbTe-based nanocomposites.

Wet comminution kinetics of dolomite at laboratory scale

Wet comminution tests of discretized dolomite sample were conducted in planetary ball mill and reported in this work. The effect of ball diameter and feed size on the comminution kinetics was investigated. Literature models were used in attempt to provide adequate selection function estimation. Rajamani and Herbst model was proposed for evaluation of the selection functions ( S j ) in planetary ball mill under given process conditions. Model parameters were correlated to ball diameters. The methodology suggested in this paper can provide assessment of model parameters and consequently S j parameters. This work represents a good foundation for further quantification of interactions in the comminution processes, and thus the prediction possibility of product properties in various process units and process conditions.

Tennis ball diameter: the effect on performance and the concurrent physiological responses

The aim of this study was to examine the influence of a pressurized tennis ball 6% greater in diameter (Type 3) than a standard sized (Type 2) ball on performance and the physiological responses to the Loughborough Intermittent Tennis Test (LITT) (Davey et al., 2002). Eight competitive tennis players (males, n = 4, age 24.8 ± 3.5 years, body mass 81.3 ± 3.1 kg, height 1.74 ± 0.02 m, estimated VO2max 54.4 ± 2.6 ml · kg-1 · min-1; females, n = 4, age 26.3 ± 3.1 years, body mass 67.0 ± 6.7 kg, height 1.68 ± 0.02 m, estimated VO2max 49.9 ± 3.3 ml · kg-1 · min-1; mean ± s x ) completed two main trials of the LITT with either the Type 2 or Type 3 tennis balls to the point of volitional fatigue. The mean time to volitional fatigue was 29.5% greater during the Type 3 trials than during the Type 2 trials (56.9 ± 6.4 min vs 40.1 ± 3.7 min; P < 0.05). The mean percentage accuracy and mean percentage consistency recorded for the entire LITT were greater for the Type 3 than the Type 2 trials (9.2 ± 1.5 vs 4.0 ± 0.3% and 61.1 ± 0.6 vs 51.3 ± 0.6%, respectively; P < 0.01). A significantly lower mean heart rate and blood lactate concentration were observed during the Type 3 than during the Type 2 trials. There was a clear effect of ball diameter on tennis performance and certain physiological responses.

A study on the specific rate of breakage of cement materials in a laboratory ball mill

The specific rate of breakage (Si) in the widely accepted first-order expression of grinding rate is one of the important factors required to evaluate a grinding process, particularly for the initial grinding stage in various mill types.In this study, the effects of ball diameter and feed size on the specific rate of breakage were investigated on limestone, trass and clinker samples at batch grinding conditions based on a kinetic model. Eight different monosize fractions were prepared between 1.7 and 0.106 mm, using a √2 sieve series. The specific rates of breakage (Si) were determined from the size distributions at different grinding times, and the specific rates of breakage were compared for three different ball diameters (41, 25.4 and 9.5 mm).The results indicated that the variation of the specific rate of breakage with feed size of cement materials could be expressed. For the specific rate of breakage of each material, empirical equations were developed to express it as a function of feed size and ball diameter.

The influence of ball size on tribological behaviour of MoS 2 coating tested on a ball-on-disk wear rig

The effect of ball diameter on wear and friction of a molybdenum disulphide (MoS 2) coating deposited using the closed-field magnetron sputtering technique has been investigated on a ball-on-disk wear rig sliding against uncoated steel ball-bearing balls. It was observed that the wear rate of the coating decreased significantly with increase in ball diameter. Correspondingly, the average friction coefficient in the steady state of sliding increased with increase in ball diameter. Under the present experimental conditions, the effect of ball size on wear and friction of the coating vanished when the diameter of the ball exceeded 6.35 mm. This phenomenon is thought to be a result of wear mode transition as a function of contact pressure at the apparent area of contact from a low-rate ‘mild’ wear regime to a high-rate ‘severe’ wear regime when the contact pressure exceeds some critical value. Simulation results using a previously presented model based on the above assumption showed a good agreement with the experimental observations.

Reduction of tantalum chloride by magnesium during reaction milling

Recent studies have demonstrated the application of 345 mechanical alloying to chemical refining [1-3]. The reduction of oxides and halides by milling with 335' strong reducing elements, such as Ca or Mg, has been reported for a number of metals and alloys, E 325including titanium [2] and rare earth permanent 2 magnet alloys [4, 5]. The reduction reaction may K occur in a steady-state manner during milling or by ~ 315 unstable thermal combustion of the reactants [6-10]. Schaffer and McCormick [9] have shown 3o5 that combustion occurs during milling if the temperature rise during ball/powder collision events 295 exceeds the ignition temperature of the reactant mixture. In this letter we report a study of the reaction of tantalum chloride with magnesium during mechanical milling. The starting materials used for milling were TaC1 s (FLUKA, 99.9%) and Mg (CERAC, 99.9%, -325 mesh). A total of 5 g of powder, including a 10% stoichiometric excess of Mg, and a ball to powder 600 mass ratio of 7:1 was used. Milling was carried out using a Spex 8000 mixer/mill with a hardened steel 500vial. The milling media consisted of hardened steel .c balls and the effect of ball diameter (d = 9.5, 6.4, 4.8 E 400 and 3.2 mm) was examined. The vials were loaded E and sealed under high-purity argon in a controlled'~ 300atmosphere glove-box. The reaction was followed by c monitoring the vial temperature during the course of .O 20O milling using a type K thermocouple attached to its ~" -~ looouter surface. Samples were taken from the vial at different stages of milling and the structures were o " analysed by X-ray diffraction (XRD) using a Sie3 mens D5000 Diffractometer with a C u K , monochromatic radiation. The morphology of the powders was examined in a Philips EM 430 transmission electron microscope (TEM) with an EDAX 9900 energy dispersive spectroscopy (EDS) system attached. Measurements of vial temperature during milling are shown in Fig. 1for the four different ball sizes used in the study. At short milling times, the vial temperature increased steadily with milling, due to the mechanical energy dissipated in the system. At a critical time, tig , a n abrupt increase in temperature occurred, which indicated the onset of combustion. The ignition time for combustion increased with decreasing ball size as shown in Fig. 2. The structural evolution during milling with 3.2 mm balls was followed by X-ray diffraction measurements (Fig. 3). The diffraction pattern after milling for 1 h is shown in Fig. 3a. Only peaks corresponding to Mg were observed, indicating the

Effect of ball mill size on media wear

Correlation of scale-up from small-scale batch laboratory mills to large-diameter industrial mills was established by performing two series of laboratory and pilot plant grinding tests using a magnetic taconite ore and a siliceous sulfide ore. In one series, controlled batch grinding tests in 203-, 508-, and 914-mm (8-, 20-, and 36-in.) diameter mills were carried out followed by a second series involving continuous grinding tests using 305-mm (12-in.) and then 1067-mm (42-in.) diameter pilot plant ball mills in open circuits. The effects of ball diameter on wear and of mill diameter on grinding power and ball wear are illustrated.