High grade

Extremely dry (or super-dry ) ethyl alcohol. The yields in several organic preparations e.g., malonic ester syntheses, reduction with sodium and ethyl alcohol, veronal synthesis) are considerably improved by the use of alcohol of 99-8 per cent, purity or higher. This very high grade ethyl alcohol may be prepared in several ways from commercial absolute alcohol or from the product of dehydration of rectified spirit with quicklime (see under 4). 

For medium and high grade materials where domains are absent in the remanent state, the remanence is given by ... 

At the present rate of world phosphate rock consumption (150 x 10 t/yr), the total world reserve (Table 14) is sufficient for about 200 years, and the resource would be sufficient for nearly 900 years. At expected increased rates of consumption, the reserves and resources are adequate for at least 150 years and 700 years, respectively. At projected rates of consumption, the high grade reserves in Florida probably will be exhausted by the year 2000. Rock production from the Florida reserve presentiy constitutes about 80% of all United States production and about one-third of world production (106). This rate of depletion is causing increased interest in western United States reserves which represent nearly 80% of present U.S. total reserves. 

Nonwoven Fabric. Crimped PVA staple is being used for the manufacture of dry-laid nonwoven. Also, as an example utilising the uniqueness of the fiber, a soft sheet is prepared by shrinking and pardy dissolving in hot water a nonwoven from water-soluble PVA fiber and then insoliibili ing the fabric by acetalization or similar processes. This sheet is used as car wipers, wipers for high grade furniture, and for similar purposes. 

Outside of the United States, there are six primary producers in China, France, Mexico, Morocco, South Africa, and Spain. Mines in Newfoundland, Canada, were closed in 1990. Both Mexico and South Africa have lost market share to China which has high grade, low cost fluorspar. China is expected to dominate world markets because reserves are vast and production cost is low. Table 3 (2) shows a Hst of world producers by country of fluorspar in the early 1990s. 

A commercial process which uses hydrothermal leaching on a large scale is the Bayer process for production of aluminum oxide (see Aluminum compounds). This process is used to extract and precipitate high grade alurninum hydroxide (gibbsite [14762-49-3]) from bauxite [1318-16-7] ore. The hydrothermal process step is the extraction step in which concentrated sodium hydroxide is used to form a soluble sodium aluminate complex ... 

Until 1990, some flaked iodine and iodine-containing wastes were sublimed to obtain an especially high grade product. This process has been dropped because of quaUty improvements in the standard operations. Sublimed iodine is produced only in small quantities by specialized companies that... 

In contrast to predictions of eventual exhaustion of high grade domestic ores of many common metals, seawater is a virtually unlimited source of magnesium. It has been estimated that 1.306 x 10 metric tons of magnesium are present in each cubic kilometer (2.6 x 10 gal) of seawater and there is an estimated 1.3 x 10 km (3.4 x 10 ° gal) of seawater on earth (3). 

Sihcon is normally used ia the form of a high grade ferrosiUcoa alloy, and the MgO is normally suppHed ia the form of dolime. EerrosiUcoa [8049-17-0] is prepared by the carbothermal reductioa of siUca ia the preseace of iroa ... 

The coarse mica concentrate is either respiraled to produce a product with a grade suitable for use by wet grinding mica producers, or floated to further upgrade it for specialty high grade dry ground mica products. 

The slime, consisting of kaolin, fine quart2, and feldspar, is sometimes used as is after being dewatered. This material may be used in the manufacture of light-colored brick or may be further processed to produce a high grade ceramic kaolin used in the manufacture of dinnerware, electrical porcelain, or sanitary-ware (see Ceramics). Floes of kaolin may be sold in bulk from the drier or pulveri2ed and sold in a powdered form. 

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