Diameters, mineral particles

Figure 18-82 illustrates the relationship between solids concentration, iuterparticle cohesiveuess, and the type of sedimentation that may exist. Totally discrete particles include many mineral particles (usually greater in diameter than 20 Im), salt crystals, and similar substances that have httle tendency to cohere. Floccnleut particles generally will include those smaller than 20 [Lm (unless present in a dispersed state owing to surface charges), metal hydroxides, many chemical precipitates, and most organic substances other than true colloids. 

A few studies on grain size of minerals in midoceanic ridge chimneys have been published. Feely et al. (1987) described the grain size of mineral particles in the smoke and sediment samples from southern Juan de Fuca Ridge. They report the following grain sizes sphalerite 0.3-100 p.m in diameter (usually less than 20 p.m) pyrite 0.1-10 p.m Fe-Si, Ca-Si phases 5-150 p.m. Converse et al. (1984) reported the grain size... 

Free settling means that the particle is at a sufficient distance from the boundaries of the container and from other particles, and that the density of the medium is that of a pure fluid, as for example, water. If two different mineral particles of densities pj and p2 and diameters d1 and d2 respectively fall in a fluid of density p3 with the same settling rate, then their terminal velocities must be the same. From Stokes law this gives for the laminar range... 

Bubbles of air or of water vapor present in a system of water, mineral matter and small masses of oil, will become attached to the oil masses and will float them to the surface. However, only small bubbles a few millimeters and less in diameter are effective in floating the oil. Air and water vapor bubbles also become attached to and float mineral particles. Particles of minerals other than quartz are floated more readily than quartz. 

The modification of polymer deformation mechanisms in the localised area between mineral particles is another toughening contribution. In our case, the ligament thickness A, is about the same size as the mean particle diameter ... 

The characteristics of flame heated silicate 3) suggest that the vitrified potassium alumino-silicate particles and the below 5 pm diameter kaolin particles are first to sinter after deposition. The flame vitrified particles have a high glass content and their small size enhances sintering, as evident from Equation (7). It is therefore to be expected that the inherent, small-particle mineral matter (Figure lb) will enhance sintering. 

Figure 3 shows the size distributions of inorganic mineral particles obtained by low temperature ashing of unprocessed oil shales. These minerals have mean particle diameters (50 percent frequency level) of 5-6 microns. 

In addition, clay particles can exhibit widely contrasting particle dimensions their ratio of particle diameter to thickness can range from 10 1 to 250 1, depending on the nature of the clay and its exchangeable ions [55]. Particles, which are frequently irregular in shape, are somewhat unique in the variety of associations that can take place in their dispersion. Figure 1.7 shows some of the modes of association among suspended clay mineral particles [75]. Such associations have a profound effect on the flow properties of these dispersions (see Section 6.5). 

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