Particle quartz

The importance of the thin film between the mineral particle and the air bubble has been discussed in a review by Pugh and Manev [74]. In this paper, modem studies of thin films via SFA and interferometry are discussed. These film effects come into play in the stability of foams and froths. Johansson and Pugh have studied the stability of a froth with particles. Small (30-/ m), moderately hydrophobic 6c = 65°) quartz particles stabilized a froth, while more hydrophobic particles destabilized it and larger particles had less influence [75]. 

Determine the settling velocity of spherical quartz particles in water (d = 0.9 mm) using the dimensionless plot of the Lyachshenko and Reynolds numbers versus the Archimedes number in the figure above. The Lyashenko number is the same as the dimensionless settling number. The specific weight of the quartz is 2650 kg/m and the temperature of the water is 20° C. 

Determine the maximum size of quartz particles settling in water (t = 20° C) that can be described by Stokes law. What is this particle s settling velocity The specific weight of quartz is 2650 kg/m ... 

Obviously, the discrepancy between the experimental data [238-241] and predictions of the theory [236,237] can be attributed to the difference of the coefficients of thermal expansion. The polymer exerts pressure on the filler, thereby masking the effect of the strength of adhesion on the modulus. The pressure on the filler may be sufficiently high. In [243] it was found, for example, that in PP, quartz particles experienced a compression force of about 100 MPa after cold drawing of the composite the force reduces to 50 MPa in the direction of drawing but at the same time increases to 300 MPa in the perpendicular direction. 

Viswanathan et al. (V6) measured gas holdup in fluidized beds of quartz particles of 0.649- and 0.928-mm mean diameter and glass beads of 4-mm diameter. The fluid media were air and water. Holdup measurements were also carried out for air-water systems free of solids in order to evaluate the influence of the solid particles. It was found that the gas holdup of a bed of 4-mm particles was higher than that of a solids-free system, whereas the gas holdup in a bed of 0.649- or 0.928-mm particles was lower than that of a solids-free system. An attempt was made to correlate the gas holdup data for gas-liquid fluidized beds using a mathematical model for two-phase gas-liquid systems proposed by Bankoff (B4). 

Wall-to-bed heat-transfer coefficients were also measured by Viswanathan et al. (V6). The bed diameter was 2 in. and the media used were air, water, and quartz particles of 0.649- and 0.928-mm mean diameter. All experiments were carried out with constant bed height, whereas the amount of solid particles as well as the gas and liquid flow rates were varied. The results are presented in that paper as plots of heat-transfer coefficient versus the ratio between mass flow rate of gas and mass flow rate of liquid. The heat-transfer coefficient increased sharply to a maximum value, which was reached for relatively low gas-liquid ratios, and further increase of the ratio led to a reduction of the heat-transfer coefficient. It was also observed that the maximum value of the heat-transfer coefficient depends on the amount of solid particles in the column. Thus, for 0.928-mm particles, the maximum value of the heat-transfer coefficient obtained in experiments with 750-gm solids was approximately 40% higher than those obtained in experiments with 250- and 1250-gm solids. 

It will be both interesting and instructive to describe the separation process principles for two substances one a quartz-magnetite, and the other a quartz-hematite. The quartz-magnetite when ground would consist of liberated quartz particles, liberated magnetite... 

The catalytic test of propane ODH reaction was performed in the 350-600°C range in a quartz fixed bed flow reactor with on line GC analysis. The free volume of the reactor after the catalyst bed was filled with quartz particles to minimize the homogeneous reactions. All the testing set was placed in a thermostat with heated lines to the gas chromatographs at about 100°C to prevent water condensation. The feed gas composition was C3H8/02/N2 = 20/10/70 vol.% at total gas flow 50 cm3 min-1. Catalyst fractions of 0.2-0.315 mm particle size and of 80 mg weight were loaded into the reactor. Before the reaction, the catalyst samples in the reactor were kept under airflow at 600°C for lh. 

Polymerization of propylene is catalyzed by phosphoric acid distributed as a thin film on quartz particles. An empirical equation is proposed (Langlois Walkey, Petroleum Refiner, p 29, August 1942) for this conversion, namely,... 

Assuming the galena and quartz particles are of similar shapes, then from equation 1.42, the required density of fluid when Stokes law applies is given by ... 

Kiinsley DH, Smalley IJ (1973) Shape and nature of small sedimentary quartz particles. Science 180 127-129... 

In the silicon carbide manufacturing process the major bioactive dusts identified are quartz particles and silicon carbide fibers generated in the process. In contrast to the silicon carbide fibers, silicon carbide particles were... 

LAYER OF HZSM5 CRYSTALLITES ON QUARTZ PARTICLES — I-------MIIH---------HI —... 

Fig. 6 Schematic drawing of ZSM5 catalyst bed deactivation. View of the fused silica reaction tube at about 40 % of catalyst life time. Black zone (I) of deactivated catalyst particles covered with coke ("methanol coke"). Small dark reaction zone (II) in which methanol conversion to 100 % occurs. Blue/grey zone (III) of active catalyst on which a small amount of "olefin coke" produced by the olefinic hydrocarbon product mixture has been deposited on the crystallite surfaces. The quartz particles before and behind the catalyst bed (zones 0) remain essentially white.

TABLE 5 COMPARISON OF HZSM5 SAMPLES FOR HIGH TEMPERATURE DEACTIVATION KITH METHANOL AS REACTANT 0.5 g ZEOLITE COATED ON 7 g QUARTZ PARTICLES (O.Z - O.R nm), CATALYST BED VOLUFt 11 cmK PcHjOH Nj ... 

Figure 11.20 Measured extinction by five aqueous suspensions of irregular quartz particles (Hodkinson, 1963) at the wavelengths 0.365, 0.436, and 0.546 (im.

Figure 12.14 Measured infrared extinction by crystalline quartz particles (dashed curves) compared with calculations for spheres (top) and a continuous distribution of ellipsoids (bottom).

Calculated and measured values of P = —Sn/Su, the degree of linear polarization, for several nonspherical particles are shown in Fig. 13.9. The prolate and oblate spheroids, cubes, and irregular quartz particles have made their appearance already (Fig. 13.8) a new addition is NaCl cubes. Also shown are calculations for equivalent spheres. 

A distinctive feature of fluidized beds is a high rate of heat transfer between the fluid and immersed surfaces. Some numerical values are shown on Figure 17.37. For comparison, air in turbulent flow in pipelines has a coefficient of about 25 Btu/(hr)(sqft)(°F). (a) is of calculations from several correlations of data for the conditions identified in Table 17.19 (b) shows the effect of diameters of quartz particles and (c) pertains to 0.38 mm particles of several substances. 

Electrophoretic mobilities of the quartz particles in cobalt (II) perchlorate solutions were determined with a calibrated Zeta-Meter apparatus. Coagulation sedimentation behavior was followed using a stop-flow type apparatus. The dispersion is pumped in a closed loop from an equilibration vessel through an optical cell located in the sample compartment of a recording spectrophotometer. From the optical densitytime curve obtained from the time the pump is switched off, the turbidity index (in arbitrary units) is obtained as the slope of the curve at zero time. 

Statement 1. Bituminous sand is an aggregate of sand, clayey matter, oil and water. The sand consists mainly of quartz particles of 50 to 200-mesh size and smaller, but also of particles of other minerals including mica, rutile, ilmenite, tourmaline, zircon, spinel, garnet, pyrite, and lignite. Clay occurs interbedded with the bituminous sand itself. Ironstone nodules of all sizes up to eight inches in diameter occur in the bituminous sand beds, especially in the southern part of the deposit. The oil is viscous, naphthenic, and of a specific... 

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