Deposit compaction

Fig. 11. Experimental filter pressure drop as a function of soot mass loading compared with the model taking into account the effect of gas compressibility (dashed line) and the effect of soot deposit compaction (continuous line). The indicative example is given for a soot aggregate size of 129 nm.

Sedimentary rock—Rock formed by deposition, compaction, and cementation of weathered rock or organic material, or by chemical precipitation. Salt and gypsum form from evaporation and precipitation processes. 

The bulk of the earth s crust consists of igneous rocks representing primary material of magmatic origin. Exposure to the atmosphere and the action of surface waters causes a small fraction of crustal rocks to undergo weathering and erosion. The debris is washed into the continental and oceanic basins, where deposition, compaction, and diagenesis convert this secondary material into sedimentary rocks. 

Among the substrates presented in Figure 7.8.8, on graphite carbon (c) a dense SiC layer ( 10pm) was formed by solid diffusion between the silicon deposit and carbon electrode. On this thin layer, a dense and adherent silicon layer of 100pm thickness was obtained. Similar results on graphite were obtained by Chevalier, who attributed the deposit compactness to the coalescence of silicon nodules in a three-dimensional growth [18]. 

Table 4.30 Comparison of Filament Winding with Other Fiber Deposition, Compacting, and Curing Processes...

Compaction is only one process of depth controlled change of porosity. Diagenesis is the process of all physical and chemical changes in sediments after deposition (compaction, cementation, recrystallization) forming a consolidated rock. 

Growth faulted deltaic areas are highly prospective since they comprise of thick sections of good quality reservoir sands. Deltas usually overlay organic rich marine clays which can source the structures on maturation. Examples are the Niger, Baram or Mississippi Deltas. Clays, deposited within deltaic sequences may restrict the water expulsion during the rapid sedimentation / compaction. This can lead to the generation of overpressures. 

Compaction occurs when continuous sedimentation results in an increase of overburden which expels pore water from a sediment package. Pore space will be reduced and the grains will become packed more tightly together. Compaction is particularly severe in clays which have an extremely high porosity of some 80% when freshly deposited. 

Manganese metal made by this process is 99.9% pure. It is in the form of irregular flakes (broken cathode deposits) about 3-mm thick, and because of its brittleness, has Httle use alone. Most of the electrolytic manganese that is used in the aluminum industry is ground to a fine size and compacted with granulated aluminum to form briquettes that typically contain 75% Mn and 25% Al. 

Miscellaneous Methods. Powdered metals such as aluminum, chromium, nickel, and copper, along with various aHoys, can be appHed to parts by electrostatic deposition. The metal strip containing the attached powdered metal must be further processed by cold rolling and sintering to compact and bond the metal powder. 

In plasma chemical vapor deposition (PCVD), the starting materials are typically SiCl, O2, 2 6 GeCl (see Plasma technology). Plasma chemical vapor deposition is similar to MCVD in that the reactants are carried into a hoUow siUca tube, but PCVD uses a moving microwave cavity rather than a torch. The plasma formed inside the microwave cavity results in the deposition of a compact glass layer along the inner wall of the tube. The temperatures involved in PCVD are lower than those in MCVD, and no oxide soots are formed. Also, the PCVD method is not affected by the heat capacities or thermal conductivities of the deposits. 

In a chemical vapor deposition (CVD) variant of conventional powder metallurgy processing, fine chromium powder is obtained by hydrogen reduction of Crl2 and simultaneously combined with fine thorium(IV) oxide [1314-20-17, H1O2, particles. This product is isostaticaHy hot pressed to 70 MPa (700 atm) and 1100°C for 2 h. Compacts are steel clad and hot roUed to sheets (24). 

Compaction, Compression, and Expression. Compaction is a newer term for compression and is used to describe the movement of particles relative to one another within a device until the matrix of particles gains enough strength to resist further consoHdation (16). Compaction occurs in a plate and frame filter both while the chamber is filling and at the end of the cycle when the chamber is nearly full and the pressure rises steeply. Compactibihty (or compressibiUty) describes the reduction in volume of the particle matrix. Compaction also takes place in the bed of a thickener as the sohds continuously deposit on the top of the bed and a thickened slurry is withdrawn from the bottom. 

In a canyon site, filling starts at the head end of the canyon (see Fig. 25-70) and ends at the mouth. The prac tice prevents the accumulation of water behind the landfill. Wastes usu ly are deposited on the canyon floor and from there are pushed up against the canyon face at a slope of about 2 to 1. In this way, a high degree of compaction can be achieved. 

It is estimated that approximately 0.9 to 2.1 m of reasonably compacted plant material was required to form 0.3 m of bituminous coal. Uifferent ranks of coal require different amounts of time. It has been estimated that the time required for deposition of peat sufficient to provide 0.3 m of the various ranks of coal was lignite, 160 years bituminous coal, 260 years and anthracite, 490 years. Another estimate indicates that a 2.4 m bed of Pittsburgh Seam (bituminous) coal required about 2,100 years for the deposition of necessaiy peat, while an anthracite bed with a thickness of 9.1 m required about 15,000 years. 

With sparingly soluble salts of lead, the compactness of the deposits may be strongly influenced by the concentration of the relevant anion. Very low concentrations frequently resulting in imperfect coatings. 

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