Minerals, Separation

Once the comminution process is completed, the succeeding operations in mineral processing are taken over by what is known as separation. Regardless of the method or methods used, the aim is always the same-to take a natural aggregate of minerals (an ore) and separate it into two or more mineral products. In general, the products of separation are (i) the concentrate which contains the valuable minerals and (ii) the tailings which contain primarily materials of little or no value. It may be borne in mind that minerals have been liberated, either by grinding or by chemical means, must usually be sized prior to 

Purification of a crude product by removing from it any contaminating impurities. 

Separation of a mixture of two or more products into the individual pure products. 

The stream discharged from a process step may consist of a mixture of product and unconverted raw material, which must be separated and the unchanged raw material recycled to the reaction zone for further processing. 

A valuable substance, such as a metallic ore, dispersed in a mass of inert material must be liberated for recovery and the inert material discarded. 

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Minerals separation Mineral violet Mineral wool Minerec Mines... 

Flotation. The method of mineral separation in which a froth created in water by a variety of reagents floats some finely cmshed minerals, whereas other minerals sink. 

Flow Sheets. AH minerals processing operations function on the basis of a flow sheet depicting the flow of soHds and Hquids in the entire plant (6,13,14). The complexity of a flow sheet depends on the nature of the ore treated and the specifications for the final product. The basic operations in a flow sheet are size reduction (qv) (comminution) and/or size separation (see Separation, size), minerals separation, soHd—Hquid separation, and materials handling. The overaH flow sheet depends on whether the specification for the final mineral product is size, chemical composition, ie, grade, or both. Products from a quarry, for example, may have a size specification only, whereas metal concentrates have a grade specification. 

Each basic operation can be divided into one or more unit operations. Size reduction involves cnishing and grinding depending on the size of material handled, and these may be carried out in stages. Separations can be either soHds from soHds, based on size or mineral composition, or soHds from Hquids, ie, dewatering (qv). Size separation or classification is an integral part of any flow sheet, not only to meet product size specifications, but also to ensure a narrow size distribution for subsequent minerals separation circuits and to decrease the load and improve the efficiency of size reduction units which are energy intensive. 

U. AssAms,Magnetohjdrodjnamic andMagnetohjdrostatic Methods of Mineral Separation,]ohss lfJ Aey Sons, Inc., New York, 1976. 

Uses. Tballium compounds have limited use in industrial appHcations. The use of thaHous sulfate in rodenticides and insecticides has been replaced by other compounds less harmful to animals (see Insect control technology Pesticides). Tb allium sulfide has been used in photoelectric cells (see Photovoltaic cells). A thallium bromide—thallium iodide mixture is used to transmit infrared radiation for signal systems. ThaHous oxide is used in the manufacture of glass (qv) that has a high coefficient of refraction. Tb allium formate—malonate aqueous solutions (Cletici s solution) have been used in mineral separations. Many thallium compounds have been used as reagents in organic synthesis in researchlaboratoti.es. 

Charging bv ion bombardment is the technique used in most mineral separations. The conductive-induction (nonionizing) plate types of separators have also been used Application.s of this device in the minerals indiisti v include its use as a final cleaning step when concentrating rutile and zircon,... 

FIG. 19-61 (i) Mineral separation hi h-capacitv 4-roll (250 nini dia X 2000 nini lon j separator... 

There are a number of industrial and technological areas in which nanoscale adhesion is important. One of the earliest fields concerned with adhesion on this scale was colloid science. Colloid particles lie in the intermediate region between macro and nano, with dimensions typically of the order of hundreds of nanometers up to a few microns. This means that their true contact areas he well within the nano-domain and are influenced by interactions on this length scale. Adhesion between such particles is important, due to its influence on mineral separation processes and on the aggregation of powders, for example, on the walls of machinery or in the forming of medical tablets. In an extraterrestrial context, such... 

Data on mineral s arates in present day volcanic rocks. Since every dating method (including the K-Ar or C systems) can be affected by several geochemical perturbations which may lead to erroneous ages, the best test for the °Th- U mineral isochrons consists in the analysis of presently erupted lavas or historic lavas of well known eruption dates. Rather surprisingly the data obtained on such samples are not so numerous (some examples are illustrated in Fig. 10). Early data showed that, in some cases, there were interlaboratory analytical discrepancies, especially in Th isotope ratios measured on mineral separates extracted from the same lava flows (this was the case for the 1971 lava from Mt. Etna and 1944 lava from Mt. Vesuvius Capaldi and Pece 1981 Hemond and Condomines 1985 Capaldi et al. 1985). This emphasizes the fact that °Th- U mineral analyses... 

Latham AG, Schwarcz HP (1987b) On the possibihty of determining rates of removal of uranium from crystalline igneous rocks using U-series disequihbria - 2 applicability of a U-leach model to mineral separates. Appl Geochem 2 67-71... 

An earlier section which dealt with mineral separation included flotation among the category of concentration separation processes. The introduction of flotation was one of the major milestones in the history of mineral processing. There exist variations (natural or artificially created) in the surface properties of mineral particles, and the technique of flotation is based on the utilization of these differences. The actual specific gravity of the mineral particle plays little or no part in the separation. 

A simple two-mineral separation, say of galena (specific gravity 7.5) from a siliceous gangue (specific gravity 2.65) can be taken as a good example to illustrate the process. The flotation operation comprises the following successive steps. 

Figure 3. Starting with the binocular microscope, discriminatory power increases in a counterclockwise direction, as indicated by the circular background. Variations in flowline width reflect the differential sampling capabilities of the techniques. Special petrological techniques include X-ray diffraction, electron and proton microprobe, staining, and heavy mineral separation.

Bulk sediment samples ( 30 kg) of till (n=63) and glaciofluvial sediments (n=7) were collected in C soil-horizon (>1 m depth) from hand-dug pits, natural bluffs, and man-made exposures. Samples underwent heavy mineral separation (SG >3.2 g/cm3) using a shaking table and heavy liquid separation. Heavy indicator minerals were visually identified and picked from the sand-sized fraction (0.25 - 2.00 mm). 

Mineral separations, 15 442 Minerals industry, size of, 16 598 Mineral sludge dewatering efficiency, poly(ethylene oxide) in, 10 688 Mineral solids, hybrid materials based on, 13 541... 

Rotor bodies, in steam turbines, 23 231 Rotor electrostatic separators, 16 643-644 Rotor rotating converter, 16 151 Rotors, molecular, 17 59-61 Rotor spinning cotton yarn, 3 17 Rotor-stator devices, 10 127 Rotor-stator disperser, 3 701 Rotor-stator mills, 13 65 Rotor-stator mixers, 16 674-675 Rotosil process, 22 412 Roughages, as ruminant feeds, 10 863 Roughing, in mineral separation, 16 604 Roughing services, magnetic drums used in, 15 446... 

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