Silicate of alumina

Salter mentions that red lead was frequently adulterated with earthy substances, such as brickdust, red ochre, and colcothar . Various additives are also mentioned by Toch, including silica, lampblack, graphite qq.v.) and silicate of alumina. Conversely, this compound has not infrequently been used to adulterate vermilion q.v. Gettens et al., 1993b). 

To accelerate the polymerization process, some water-soluble salts of heavy metals (Fe, Co, Ni, Pb) are added to the reaction system (0.01-1% with respect to the monomer mass). These additions facilitate the reaction heat removal and allow the reaction to be carried out at lower temperatures. To reduce the coagulate formation and deposits of polymers on the reactor walls, the additions of water-soluble salts (borates, phosphates, and silicates of alkali metals) are introduced into the reaction mixture. The residual monomer content in the emulsion can be decreased by hydrogenizing the double bond in the presence of catalysts (Raney Ni, and salts of Ru, Co, Fe, Pd, Pt, Ir, Ro, and Co on alumina). The same purpose can be achieved by adding amidase to the emulsion. 

To overcome the limitations of natural zeolites a whole range of synthetic zeolites have been manufactured since the 1950s. These have tailored pore sizes and tuned acidities, as well as often incorporating other metal species. The basic synthesis involves mixing a source of silica, usually sodium silicate or colloidal Si02, with a source of alumina, often sodium aluminate, and a base such as sodium hydroxide. The mixture is heated at temperatures up to 200 °C under autogenous pressure for a period of a few days to a few weeks to allow crystallization of the zeolite. 

In the late 1940s zeolites were synthesized according to the procedure shown in Fig. 3.24. First an amorphous alumino-silicate gel is formed. This process is completely analogous to the production of alumina and silica gels described before. Subsequently this gel is crystallized into zeolite. The preparation of zeolites has drawn tremendous attention of the scientific and industrial community. A wide variety of zeolites have been synthesized, and reproducible synthesis procedures have been reported (often in the patent literature). Natural zeolites also exist massive deposits have been discovered in many places in the world. 

Direct entry of alumina adjuvants through the skin may occur by the use of therapeutic vaccines, with a resultant transient uptake of aluminium in the brain (Redhead et al., 1992). The injection of talc (magnesium silicate)-containing drugs intended for oral consumption has been shown to induce progressive pulmonary fibrosis in drug abusers (Pare etal., 1989). 

In the catalytic cracking method, a suitable catalyst such as aluminum silicate or alumina is used. This provision produces an improved quality and yield of gasoline. This method has several advantages over the thermal cracking method. Among these, special mention... 

In a large number of oxide flotation plants, sodium silicate (Na2Si03) is used as a gangue depressant. In the past two decades, a new line of depressants has been developed and introduced into a number of operating plants. Some of these depressants include (a) a mixture of sodium phosphate and lignin sulphonate (i.e. depressant 3XD), (b) a mixture of a low-molecular-weight acrylic acid and sodium silicate (depressant 2D) and (c) hydrosol based on the reaction of sodium silicate with alumina sulphate (depressant SD). These depressants were extensively examined on copper oxide ores from the Nchanga mine in Zambia. 

Portland cement refers to a class of hydraulic cements in which the two essential constituents are tricalcium silicate (3Ca0-Si02) and dicalcium silicate (2Ca0-Si02) with varying amounts of alumina, tricalcium aluminate, and... 

The manufacture of Portland concrete consists of three basic steps—crushing, burning, and finish grinding. As noted earlier, Portland cement contains about 60% lime, 25% silicates, and 5% alumina with the remainder being iron oxides and gypsum. Most cement plants are located near limestone (CaCOs) quarries since this is the major source of lime. Lime may also come from oyster shells, chalk, and a type of clay called marl. The silicates and alumina are derived from clay, silicon sand, shale, and blast-furnace slag. 

The acidic properties of alumina pillared clays have been extensively studied from the interest in using the pillared clays as cracking catalysts [21-24]. Sakurai et al. [25] studied the acidic properties of the alumina pillared clays with different kinds of silicate layers and concluded that the alumina pillars between the silicate layers did not have any acidity and that the role played by the pillars was only to make the original acidity of the silicate interlayers more easily accessible through opening the interlayer spaces. 

Calcium—Silicon. Calcium—silicon and calcium—barium—silicon are made in the submerged-arc electric furnace by carbon reduction of lime, silica rock, and barites. Commercial calcium—silicon contains 28—32% calcium, 60—65% silicon, and 3% iron (max). Barium-bearing alloys contains 16—20% calcium, 9—12% barium, and 53—59% silicon. Calcium can also be added as an alloy containing 10—13% calcium, 14—18% barium, 19—21% aluminum, and 38—40% silicon These alloys are used to deoxidize and degasify steel. They produce complex calcium silicate inclusions that are minimally harmfiil to physical properties and prevent the formation of alumina-type inclusions, a principal source of fatigue failure in highly stressed alloy steels. As a sulfide former, they promote random distribution of sulfides, thereby minimizing chain-type inclusions. In cast iron, they are used as an inoculant. 

Currently, the only biological barrier registered as a biochemical pest control agent is kaolin, a clay mineral [47]. Kaolin is a ubiquitous clay substance found in soils worldwide and consists of a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra [Al2Si205(0H)4]. 

Gibbsite and the "neutral lattice" minerals, 1 1 or 2 1 represent the extremes of chemical variat.on in the clay minerals. Gibbsite is a hydrated form of alumina. Kaolinite and pyrophyllite can be considered to be strictly aluminum-silicates, i.e., no ions other than Al, Si, 0, H are present in appreciable quantities in these minerals. This is not as... 

Silicate of soda, lime, alumina, and oxide of iron. Example —Coarse grew wine-bottle glass. 

Window-Glass, including English crown and cylinder or sheet-glasstins is a silicate of potassa or soda, lime, and alumina. 

The Flux.—It will bo seen, by referring to the different qualities of the ores of iron, that mostly ah of them contain small quantities of other matters and that when these are silica and alumina, which are the most common, either separately or together, they are infusible In the blast furnace but At a temperature below that of melting iron, they will combine, with the oxides of other metals, and form with them combinations that are fhaible. The oxides of iron combine readily with silica, and form a silicate of iron which is very easily fused. If, then, a mixture of lion ore and cool he put into the blast furnace, the reactions may be represented as somewhat like the following, Suppose a mixture is taken of clay and black band, composed as under —... 

A chrome yellow that is coated with large amounts of silicate and alumina and which shows improved stability to temperature, light, and chemicals is also produced by Du Pont [3.136]. 

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