Transport silica

Perhaps the most important waterside problems relate to the likelihood of boiler surface deposits and their control. High concentrations of caustic or salines only occur if porous deposits are present. It is much better to remove the cause of deposition problems than to try to manage their effects, and modem iron and silica transport polymers, together with improved cleaning protocols, have done much to limit deposition in large boilers. 

Aplin, A. C. and E. A. Warren, 1994, Oxygen isotopic indications of the mechanisms of silica transport and quartz cementation in deeply buried sandstones. 

For the case in which the blend components were steamed together, the electron microprobe analyses showed the presence of silica on Additive R. This means that silica was transported from the cracking catalyst particles to the Additive R particles during the steam deactivation. The amount of silica transported and the distance the silica penetrated into the Additive R particles varied from particle to particle. The silica penetration ranged from about 10 microns to complete penetration of an entire particle. The amount of silica transported, expressed as the peak concentration observed in the outer section of the particle, varied from about 0.5% to about 8% SiO (estimates). 

Commercially-aged samples of Additive R, taken from two commercial units, looked like the steamed sample. The silica penetration varied from about 8 microns to complete penetration of the entire particle. The amount of silica transported varied from about 1.5% to about 14% SiO (peak concentration in the particle). 

Silica may be transferred to the site of silcrete development by wind and/or water. Quartz dust, for example, may be transported considerable distances from desert areas by the wind (Goudie and Middleton, 2001). Similarly, plant phytoliths, sponge spicules and diatoms can be subject to aeolian transport (Clarke, 2003). All other transfers rely upon silica transport in solution as undissociated monosilicic acid, either as the monomer H4Si04 or the dimer H6Si207 (Dove and Rimstidt, 1994). Organic or inorganic complexes may also be formed. 

Silica transport under hydrothermal conditions is cited to support some mechanistic postulations regarding Structure IV. Why should the explanation for the occupancy factor in Structure IV be qualitatively different than for Structure II, since Structure IV only received an intensification of the treatment given Structure II The type of hydro-thermal environment present can have an important bearing on this silica transport phenomenon. In view of your use of ammonium sulfate, did you in fact achieve the conditions for transport cited by Wyart and Sabatier Residual sulfate would be expected to be quite persistent in such a system. A further point regarding Structure IV is that we have found that the lattice parameter is a smooth function of the degree of calcination severity, so that it might be expected to be smaller than the lattice parameter for Structure III on that basis alone. 

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