Bulk mineral particles

Soil is a relatively thin layer of unconsolidated matter on the surface of the earth, in which there is biological activity. The bulk of most soil consists of a mixture of extremely small, loose particles of minerals and organic matter the mineral particles are derived from the weathering of rocks the organic matter from the dead remains of living organisms (Rowell 1994 Limbrey 1975). The composition and texture of the soil are altered by human habitation humans change the natural flora and fauna of entire areas, their activ-... 

Recent work reported a method for estimating the mineral content of coals based on the electron-mlcroprobe-determlned chemical composition of discrete particles. (1,2) Each particle Is assumed to contain only one mineral component. Possible ambiguities In qualitative Identification of discrete mineral particles can be eliminated by XRD analyses of the bulk material to Identify the minerals present. For most geological materials, such separations are not readily obtainable. Thus, this method Is limited to materials that can be dispersed Into particles composed of single minerals. 

The SEM-AIA results contain very detailed information for the composite coal/mineral particles and their component parts (i.e., information on size, phase identification, and associations) which can be presented in a number of ways. Tables can be prepared to show the distribution of the sample as a function of particle size and to show the coal-mineral association in terms of bulk properties or in terms of surface properties. For bulk properties, the distribution of coal and minerals is prepared as a function of the total mineral content of the individual particles which can be related to particle density. For surface properties, coal and mineral data are tabulated as a function of the fraction of particle surface covered by mineral matter which can be used to predict the surface properties of the particles and their behavior during surface-based cleaning. Examples of these distributions are given below. 

The most important step in any aqueous extraction scheme is facilitation of the transfer of mineral particles from the bituminous matrix to the aqueous phase (Fig. 1). This process appears to be more favorable in the Athabasca tar sands than in other tar sands due to a postulated, but unobserved, film of absorbed water present on the mineral particles. The transfer process may be visualized in 2 stages 1) the transition from complete immersion in the bulk bituminous phase to partial contact with both phases, and 2) the transition from partial contact with both phases to complete immersion in the aqueous phase (Fig. la,b). 

The above processes involve separation based either on bulk properties (for example, size, density, shape, etc.) directly or by subtle control of the chemistry of the narrow interfacial region between the mineral particle and the aqueous solution in which it is suspended. In the processing of certain ores, such as those of uranium, gold or oxidized copper, chemical alteration of the minerals may be required to recover the valuable metals. These techniques are not discussed here, except to include those aspects which are directly related to surfaces and interfaces. 

If the sole mechanism of ion adsorption is via the diffuse-ion swarm, the anions in an electrolyte solution in which clay mineral particles are suspended will, in general, be excluded from a portion of the suspension volume near the particle surface [23,27]. If q- is the specific adsorbed charge of anions resulting from this exclusion and c is their bulk concentration in a 1 1 electrolyte... 

Nanoparticles are discrete nanometer (10 m)-scale assemblies of atoms. Thus, they have dimensions between those characteristic of ions (lO m) and those of macroscopic materials. They are interesting because the number of atoms in the particles is small enough, and a large enough fraction of them are at, or near surfaces, to significantly modify the particle s atomic, electronic, and magnetic structures, physical and chemical properties, and reactivity relative to the bulk material. Nanoparticle surfaces themselves may be distinctive. Particles may be terminated by atomic planes or clusters that are not common, or not found, at surfaces of the bulk mineral. These, and other size-related effects will lead to modified phase stability and changes in reaction kinetics. 

Some amount, less than 35% of the Pu in these experiments, appears to migrate at a rate of about ten times faster than the bulk of the Pu. The amount of the more rapidly migrating species appears to vary widely and is undoubtedly affected by the chemical milieu and kinetics. The rapidly migrating species may be a polymeric form of Pu, either by itself or absorbed on fine mineral particles. Evidence for these conclusions is shown by ... 

When mineral particles are contacted with water, they will undergo dissolution, the extent of which is dependent upon the type and concentration of chemicals in solution. The dissolved mineral species can undergo further reactions such as hydrolysis, complexation, adsorption and even surface or bulk precipitation. The complex equilibria involving all such reactions can be expected to determine the interfacial properties of the particles and their flotation behavior. The concentration of each dissolved mineral species can be calculated from various solution equilibria of the minerals. The calculated results are plotted as log C-pH diagram. The equilibria in selected salt-type mineral systems with special reference to calcite and apatite are examined below. 

At intermediate concentrations (10 to 2 x 10 mol/1. Region II), the solubility Umit of calcium and magnesium oleates may exceed in the interfacial region but not in the bulk solution. Then, surface precipitation of oleate on the mineral particles occurs leading to an increase in oleate depletion and a decrease in the levels of dissolved calcium and magnesium species. The hydrocarbon tails of the oleate molecules would be oriented towards the bulk making the mineral surface hydrophobic. 

The process of vectorial crystal aggregation plays no role in the determination of the structure or morphology of the crystallites comprising the bulk mineral since it orientates preformed particles of determined size in space. Crystallite structure and morphology must thus be determined by localised chemical control over the formation of the discrete mineral particles prior to spatial alignment. 

A number of techniques have been used to determine mineralogies of coal As discussed in a recent review (J ) the most common techniques are x-ray diffraction infrared spectroscopy optical microscopyy and electron microscopy. X-ray diffraction and infrared spectroscopy can be considered "bulk methods because they are generally best performed on the mineral-matter concentrate obtained by removal of the macerals by low-ten5>era-ture ashing ( 2 ) The microscope methods can be considered "particulate methods because mineral grains in the coal are sized and classified individually These microscope methods are usually used without separation of minerals and macerals because the coal macerals can serve as a background matrix to separate mineral particles and to provide contrast for the dimensional measurement of the particle ... 

The synchrotron radiation-based X-ray techniques presented here are powerful tools for characterizing the speciation of metals in house dust samples because of the metal specificity, high spatial resolution and ability to examine elements of interest with Uttle to no sample preparation or pre-treatment. Bulk XAFS analysis can be used to infer the chemical speciation of an element of interest in both moist and dry samples while p-XEF and p-XRD can determine the spatial relationship between trace metals and associated mineral particles. 

Notice that other PG/silica samples have the H NMR spectra (not shown here) of a similar shape. Broad (proton resonance line width >30 ppm) and narrow (width <3 ppm) signal components are observed at 250narrow component is caused by protons of interfacial mobile (so-called nonfreezable) water at the boundary of ice/water/surface of nanoparticles. The broad component is connected to the amorphous ice, which strongly differs from the bulk ice. The mobility of water molecules in such amorphous ice is higher than in bulk ice but it is slower than that in mobile (unfrozen at T< 273 K) water adsorbed on a surface of mineral particles. It is known... 

NICA isotherm for competitive binding. Diverse electrostatic models are considered, mainly based on one out of two concepts the impermeable sphere model (similar to a mineral particle) or the Dorman phase model, where a certain volume is assumed to be in Donnan equilibrium with the bulk. Considering these contributions, several models are proposed in the end showing similar fitting quality to titration curves because these curves have poor sensitivity to the many adjustable parameters additional, independent data are needed to improve modeling of cation binding to HSs. 

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