Glass mineral sources

Melt forming is applied to the production of relatively massive particles from silicate glasses, themselves readily produced free from deleterious impurities using cheap mineral sources. The principal attraction of the method is the abiUty to control particle shape and the principal applications in the present context are in the production of fibres and spheres. 

The two mineral sources for strontium are the sulfate (celes-tite) and carbonate (strontianite). In 2001, 75% of strontium used in the US went into the manufacture of faceplate glass in colour television cathode-ray tubes in order to stop X-ray... 

The two mineral sources for strontium are the sulfate (celes-tite) and carbonate (strontianite). The main use of strontium is as a component in colour television faceplate glass ( 8% SrO is incorporated into the glass) where its function is to stop X-ray emissions from the cathode ray tube (CRT). However, the increasing market for CRT-free flat-screen televisions is having a dramatic effect on the demand for strontium. Other uses of strontium include ferrite ceramic magnets and pyrotechnics (see Flame tests in Section 12.3). 

Typical ranges of enamel compositions are Hsted in Table 2. Raw materials (Table 1) for the glass batch include minerals, such as feldspars and quartz, because these are inexpensive sources of Si02 and AI2O2 (see Clays). The batch composition for cover coats is comprised primarily of manufactured chemicals of known, controlled levels of purity to maintain reproducible, clean colors. 

Other Considerations Autoignition can occur if combustible fluids are absorbed by wicking-type insulations. Chloride stress corrosion of austenitic stainless steel can occur when chlorides are concentrated on metal surfaces at or above approximately 60°C (140°F). The chlorides can come from sources other than the insulation. Some calcium sihcates are formulated to exceed the requirements of the MIL-I-24244A specification. Fire resistance of insulations varies widely. Calcium sihcate, cellular glass, glass fiber, and mineral wool are fire-resistant but do not perform equally under actual fire conditions. A steel jacket provides protection, but aluminum does not. 

The composition of the particles is related to that of the source rocks. Quartz sand [composed of silica (silicon dioxide)], which makes up the most common variety of silica sand, is derived from quartz rocks. Pure quartz is usually almost free of impurities and therefore almost colorless (white). The coloration of some silica sand is due to chemical impurities within the structure of the quartz. The common buff, brown, or gray, for example, is caused by small amounts of metallic oxides iron oxide makes the sand buff or brown, whereas manganese dioxide makes it gray. Other minerals that often also occur as sand are calcite, feldspar and obsidian Calcite (composed of calcium carbonate), is generally derived from weathered limestone or broken shells or coral feldspar is an igneous rock of complex composition, and obsidian is a natural glass derived from the lava erupting from volcanoes see Chapter 2. 

Borax decahydrate occurs in nature as mineral, borax (tincal). It is one of the most common sodium borate ores. The compound has several industrial applications. The refined material is mostly used in household cleaning products. It is used to make pyrex and other horosilicate glasses. Borax is added to fertilizers in small quantities as a source of boron, as a trace nutrient for plants. High purity grade borax is used in cosmetics, toilet products and electrolytic capacitors. It also is used in fire retardants, adhesives and herbicides. 

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