Deposited bed

Lager-schale,/. Mach.) bush, bushing, -stfitte, /. Geol.) deposit, bed. 

The distribution of ferroan calcite in the Oseberg Formation is very heterogeneous at field and well scales. Calcite occurs in one well out of four and is typically restricted to particular depth intervals about 1-6 m thick. Calcite-cemented intervals are readily detected on wireline logs as porosity drops abruptly, from 20-30% to less than 5%- The upper and lower boundaries are distinctly abrupt and sharp. Detailed examination of wireline logs indicates that calcitized intervals occur at different levels within the Oseberg Formation, and caimot be correlated between nearby wells. Therefore, they are not related to any continuous depositional bed. Most cemented intervals are found in the lower part of the formation, within 10 m of the lower boundary, and occur in the oil zone as well as in the water zone. 

Besides the molybdenum minerals there are five genetic types of molybdenum deposits porphyry deposits contact-metamor-phic zones in intrusive granites quartz veins pegmatites and deposits bedded in sedimentary rocks. The first three types are of hydrothermal origin and provide almost all of the molybdenum currently mined. Currently, the porphyry deposits (range from 0.05 to 0.25% Mo) are of prime importance industrially, and are predominantly mined. Secondary copper-molybdenum porphyry deposits contain much lower molybdenum concentrations (0.01-0.05% Mo), so that molybdenum can only be recovered as a byproduct. 

Let us examine first the bottom deposit (bed load), the formation of which is related directly to the magnitude of adhesive interaction. Particles on the bottom of a river have various sizes and shapes. We may find particles with equivalent diameters from a few microns to several millimeters or even larger. 

It has been found that the detachment of particles of bottom deposits (bed load) with a density of (1.04-4.15) 10 kgf/m takes place under conditions such that the ratio v djv is greater than 10, and the value of l/i/ o is 0.03 [351, p. 294]. When v djv increases from 10 to 400, the value of I/i/zq also increases, from 0.03 to 0.06. 

From the foregoing discussion, it is clear that adhesive interaction determines the course of riverbed evolution. From the magnitude of the adhesive interaction, we can estimate the velocity required to move the bottom deposits (bed load) and also the velocity below which no scouring of the bottom will take place. 

For flows above a deposited bed (flows with saltation), SRC (2000) proposed to treat the upper layer as a noncircular flow. This means that the hydraulic diameter must be determined from the wetted area. The difference in roughness between these two surfaces (upper surface of the bed) and pipe roughness is not weU discussed. The hydraulic diameter is calculated as Dug = AA ( WP. ... 

At deposition, the flow rate in the upper layer ( f/ls lower than the flow rate through the deposited bed Qg, and from the ratio of velocities as per Equation 4-57 ... 

Certain minerals, however, such as sylvite, carnallite, langbeinite, and polyhalite are found in ancientlake and sea beds and form rather extensive deposits from which potassium and its salts can readily be obtained. Potash is mined in Germany, New Mexico, California, Utah, and elsewhere. Large deposits of potash, found at a depth of some 3000 ft in Saskatchewan, promise to be important in coming years. 

Resources for Potash Fertilizers. Potassium is the seventh most abundant element in the earth s cmst. The raw materials from which postash fertilizer is derived are principally bedded marine evaporite deposits, but other sources include surface and subsurface brines. Both underground and solution mining are used to recover evaporite deposits, and fractional crystallization (qv) is used for the brines. The potassium salts of marine evaporite deposits occur in beds in intervals of haUte [14762-51-7] NaCl, which also contains bedded anhydrite [7778-18-9], CaSO, and clay or shale. The K O content of such deposits varies widely (see Potassium compounds). 

Boron. Virtually all United States boron production and about three-fifths of the world production comes from bedded deposits and lake brines in California. U.S. reserves are adequate to support high production levels. Turkey is the only other boron-producing country of significance. Only about 5% of boron production is used in agriculture. 

Fluorspar occurs in two distinct types of formation in the fluorspar district of southern Illinois and Kentucky in vertical fissure veins and in horizontal bedded replacement deposits. A 61-m bed of sandstone and shale serves as a cap rock for ascending fluorine-containing solutions and gases. Mineralizing solutions come up the faults and form vein ore bodies where the larger faults are plugged by shale. Bedded deposits occur under the thick sandstone and shale roofs. Other elements of value associated with fluorspar ore bodies are zinc, lead, cadmium, silver, germanium, iron, and thorium. Ore has been mined as deep as 300 m in this district. 

There are, however, a variety of other sources of methane that have been considered for fuel supply. Eor example, methane present in coal (qv) deposits and formed during mining operations can form explosive mixtures known as fire damp. In Western Europe, some methane has been recovered by suction from bore holes drilled in coal beds and the U.S. Bureau of Mines has tested the economic practicaUty of such a system. Removal of methane prior to mining the coal would reduce explosion ha2ards associated with coal removal. As much as 11.3 x 10 (400 trillion (10 ) cubic feet or 400 TCE) of... 

Diameters of the holes vary from 5—25.4 cm. Drilling perpendicularly to the deposit is preferable but ia folding or tilted beds inclined drilling is often practiced. Spaciag of the holes and borehole diameters depend on the hardness and fracturiag characteristics of the stone, and desired top size for the primary cmsher. 

Ammonium Ion Removal. A fixed-bed molecular-sieve ion-exchange process has been commercialized for the removal of ammonium ions from secondary wastewater treatment effluents. This application takes advantage of the superior selectivity of molecular-sieve ion exchangers for ammonium ions. The first plants employed clinoptilolite as a potentially low cost material because of its availability in natural deposits. The bed is regenerated with a lime-salt solution that can be reused after the ammonia is removed by pH adjustment and air stripping. The ammonia is subsequentiy removed from the air stream by acid scmbbing. 

Quartz-Pebble Conglomerate Deposits. Known quartz-pebble conglomerate ores are restricted to a specific period of geologic time. These ore types occur in basal Lower Proterozoic beds unconformably situated above Archaean basement rocks composed of granitic and metamorphic strata. A number of commercial deposits are located in Canada and South Africa. Some subeconomic occurrences have been reported in Brazil and India... 

Continental Shelf. Most consohdated mineral deposits found on the continental shelf are identical to those found on land and are only fortuitously submerged. Exceptions include those laid down in shallow marine seas or basins in earlier geochemical environments such as bedded ironstones, limestones, potash, and phosphorites. 

In the remote Negev desert region of Israel, oil shale is being burned in a duidized-bed combustor to supply process heat and produce electric power. Unlike the Estonian kukersite, this oil shale is lean, about 63 L/1, but is being mined to access an undedying phosphate deposit (26). 

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