Silicate secondary

Consists of clay, mud, and silt, mainly aluminum silicates Dense fine-grained rock containing mainly clay Contains silicates secondary product... 

In spite of these efforts, significant quantities of metal-bearing wastes, ha2ardous or not, continue to be earmarked for disposal rather than reclamation. There are several reasons. Often the wastes are mixed from several process streams, contain relatively low concentrations of many recoverable metals, and may contain high concentrations of water, silicates, and secondary metals, such as calcium and iron. 

Ash. This is a secondary source and is the by-product of coal combustion. It contains silicates. 

The primary types of corrosion inhibitor treatments employed are generally based on inorganic chemicals such as sodium nitrite (together with combinations of borate, silicate, molybdate, and phosphate) and the addition of even 2 to 3 pints (0.95-1.4 liters) to a boiler can immediately raise the TDS in the BW to a level at which priming can occur. Secondary problems include an associated rise in the level of BW suspended solids and sludge. 

Steam blanketing results in a departure from nucleate boiling (DNB) and typically dryout (localized total evaporation) conditions. It also may result in the formation of secondary (silicate-based) deposits that cannot be rinsed or resolublized, overheating problems, and eventual boiler tube or furnace shell rupture. 

Secondary minerals. As weathering of primary minerals proceeds, ions are released into solution, and new minerals are formed. These new minerals, called secondary minerals, include layer silicate clay minerals, carbonates, phosphates, sulfates and sulfides, different hydroxides and oxyhydroxides of Al, Fe, Mn, Ti, and Si, and non-crystalline minerals such as allophane and imogolite. Secondary minerals, such as the clay minerals, may have a specific surface area in the range of 20-800 m /g and up to 1000 m /g in the case of imogolite (Wada, 1985). Surface area is very important because most chemical reactions in soil are surface reactions occurring at the interface of solids and the soil solution. Layer-silicate clays, oxides, and carbonates are the most widespread secondary minerals. 

As part of a study of the secondary chemistry of members of Cistus (the rock-rose) in France, Robles and Garzino (1998) examined the essential oil of C albidus L. Plants were sampled from two areas in Provence characterized by different soil types, calcareous sites west of Marseille, and siliceous sites near Pierrefeu-du-Var and Bormes les Mimosas (PF and BM, respectively, in Fig. 2.23), which lie about 60 km and 80 km to the east, respectively, in the Massif les Maures. Regardless of the soil type, a-zingiberene [88] (Fig. 2.24) was the dominant component. Concentrations of other major components of the plants varied between the two soil types, as summarized in Table 2.6. Many other compounds were present in lesser amounts, but varied little between the two areas. A more recent paper by the same workers (Robles and Garzino, 2000) described an analysis of C. monspeliensis L. leaf oils, the results of which are summarized in Table 2.7. 

The Si04 tetrahedra can be arranged into several silicate units, e.g. squares, six-or eight-membered rings, called secondary building blocks. Zeolite structures are then built up by joining a selection of building blocks into periodic structures. 

Another biological disadvantage is that dental silicate cement does not bond to tooth material, and harmful substances and bacteria can percolate between it and the tooth, giving rise to secondary caries and pulpal irritation (Going, Massler Dute, 1960). These effects are magnified when dissolution of the cement occurs. 

Hals, E. (1975). Histology of natural secondary caries associated with silicate cement restorations. Archives of Oral Biology, 20, 291-6. 

Halse, A. Hals, E. (1976). Electron probe microanalysis of secondary carious lesions adjacent to silicate fillings. Calciferous Tissues Research, 21, 183-93. 

Smectite is the first secondary mineral to form upon rock weathering in the semi-arid to sub-humid tropics. Smectite clay retains most of the ions, notably Ca2+ and Mg2+, released from weathering primary silicates. Iron, present as Fe2+ in primary minerals, is preserved in the smectite crystal lattice as Fe3+. The smectites become unstable as weathering proceeds and basic cations and silica are removed by leaching. Fe3+-compounds however remain in the soil, lending it a reddish color aluminum is retained in kaolinite and A1-oxides. Leached soil components accumulate at poorly drained, lower terrain positions where they precipitate and form new smectitic clays that remain stable as long as the pH is above neutral. Additional circumstances for the dominance of clays are ... 

Most primary and secondary minerals found in soil systems are barely soluble in the soil solution. The amount of mass from the bulk phase to hydrated ions in soil solution is negligible compared to the total mass of the solid phase. In arid and semi-arid soils, concentrations of most trace metals in soil solution may be controlled by their carbonates and to some extent by their hydroxides. Other than carbonates, trace elements in arid and semi-arid soils may also occur as sulfate, phosphate or siliceous compounds, or as a minor component adsorbed on the surface of various solid phase components. The solubility of carbonates, sulfates and other common minerals of trace elements in arid and semi-arid soils will be discussed in Chapter 5. Badawy et al. (2002) reported that in near neutral and alkaline soils representative of alluvial, desertic and calcareous soils of Egypt, the measured Pb2+ activities were undersaturated with regard to the solubility of... 

The initial transition of dissolved silicate molecules into solid nanoparticles is perhaps the least explored step in the synthesis of zeolites. One impediment to understanding this mysterious step is the poorly elucidated molecular composition of dissolved particles. The major mechanistic ideas for the formation of zeolites approach these structures differently i) many researchers believe that secondary building units (SBU) must be present to form initial nanoslabs [1,2] ii) some others prioritize the role of monomers to feed artificially introduced crystal nuclei or assume that even these nuclei form via appropriate aggregation of monomers [3] iii) silicate solutions are also frequently viewed as random mixtures of various siloxane polymers which condense first into an irregular gel configuration which can rearrange subsequently into a desired crystal nucleus at appropriate conditions [4,5],... 

Van Hooijdonk, M.C.J.M., Gerritsen, G., and Brandsma, L., Preparation of primary and secondary alkyl phosphines from elemental phosphorus or phosphorus trichloride in organic solvents, Phosph., Sulf, Silic. Relat. Elem., 162, 39, 2000. 

The reagent scheme generally used in these concentrators is presented in Table 19.9. Sodium silicate is used as the common depressant, and also acts as a dispersant together with the soda ash. In the majority of operating plants, Na2S 9H20 is used as the principal activator. Some operating plants in Zambia use NaHS as a sulphidizer. Sodium or potassium xanthates are the principal collectors used, where mercaptans are used as secondary collectors. 

Lithium oxide(s), 15 134, 141 Lithium perchlorate, 3 417 15 141-142 dessicant, 3 360 in lithium cells, 3 459 Lithium peroxide, 15 142 18 393 Lithium phosphate, 15 142 Lithium-polymer cells, 3 551 in development, 3 43 It Lithium primary cells, 3 459-466 Lithium production, 9 640 Lithium products, sales of, 15 121 Lithium salts, 15 135-136, 142 Lithium secondary cells, 3 549-551 ambient temperature, 3 541-549 economic aspects, 3 551-552 high temperature, 3 549-551 Lithium silicate glass-ceramics, 12 631-632... 

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