Magnesium Oxide Dust

Examination of 95 workers exposed to an unspecified concentration of magnesium oxide dust revealed slight irritation of the eyes and nose the magnesium level in the serum of 60% of those examined was above the normal upper limit of 3.5mg/dl. No evidence of any pulmonary inflammatory response was found in six volunteers after short-term (36min) exposure to high concentrations (137.0mg/m ) of fine and ultrafine magnesium oxide particles. ... 

Contact with magnesium oxide dust or fumes may irritate the skin, eyes, or respiratory system. Symptoms of exposure may include fatigue and lethargy. The greatest concern for such health hazards rests with people who come into contact with the pure product in their line of work. 

Safety. Magnesium oxide (fume) has a permissible exposure limit (PEL) (134) (8 hours, TWA), of 10 mg/m total dust and 5 mg/m respirable fraction. Tumorigenic data (intravenous in hamsters) show a TD q of 480 mg/kg after 30 weeks of intermittent dosing (135), and toxicity effects data show a TC q of 400 mg/m for inhalation in humans (136). Magnesium oxide is compatible with most chemicals exceptions are strong acids, bromine pentafluoride, chlorine trifluoride, interhalogens, strong oxidizers, and phosphorous pentachloride. 

Oil and Metal Incendiary Mixtures. PTl is a complex mixture composed of magnesium dust, magnesium oxide, and carbon (qv), along with an adequate amount of petroleum (qv) and asphalt (qv) to form the paste (7). The U.S. developers have adopted the formula type c paste (goop),... 

Sand that is used in filtration must be free of clay, dust, and other impurities. The ratio of lime, lime-stone, and magnesium oxide will have to be lower than 5 weight percent. The standard guide value of the quality of fresh sand is to be below 2% soluble matter at 20 °C within 24 hours in hydrochloric acid of a 20 weight percent concentration. 

FIGURE 26.4 Master curves on smooth, wavy glass, on a sihcon carbide track dusted with magnesium oxide and on a clean silicon carbide track of three acrylate-butadiene rubber (ABR) compounds as gum rubber, filled with 20 pphr carbon black and 50 pphr, respectively. (From Grosch, K.A., Sliding Friction and Abrasion of Rubbers, PhD thesis, University of London, London 1963.)... 

FIGURE 26.58 Abrasion of two natural rubber (NR) tread compounds, one unprotected, the other with two parts Nonox ZA on a knurled Aluminum and a knurled steel surface, respectively, in the presence of (a) magnesium oxide (MgO) powder and (b) a dust mix of Fuller s earth and alumina powder. (Deduced from Schallamach, A.,Appl. Pol. Sci., 12, 281, 1968.)... 

In the simplified extraction apparatus (Fig. 27 on p. 35) 100 g. of finely powdered tea or tea dust are extracted for eight hours with 400 c.c. of alcohol. The alcoholic extract is then added to a suspension of 50 g. of magnesium oxide in 300 c.c. of water, and the whole is evaporated to dryness on the steam bath in a porcelain basin with frequent stirring. The pulverulent residue is boiled once with 500 c.c. and then three times with 250 c.c. of water and filtered while hot at the pump. 

A furnace similar to the Tomlinson kraft recovery furnace is used for the combustion of magnesium-based sulfite spent liquors. In this case, however, no smelt is obtained instead the base is completely recovered as magnesium oxide in dust collectors the sulfur escapes as sulfur dioxide and is absorbed from the combustion gases in scrubber towers. However, because magnesium hydroxide has a very low solubility in water, a complete recovery of sulfur dioxide meets difficulties. 

Dust recovery from calcination processes e.g., magnesium oxide production. 

It is typical to install the spray-dryer before the plant fly-ash collector, so that the existing dust control equipment can be used to collect the used absorbent. Slaked lime [Ca(OH)2] is the most common absorbent, although sodium carbonate (Na2C03) is used in some plants. Spray-dryers have also been used with regener-able magnesium oxide absorbent. " ... 

Stenback F, Sellakumar A, Shubik P. 1975. Magnesium oxide as carrier dust in benzo[a]pyrene-induced lung carcinogenesis in Syrian hamsters. J Natl Cancer Inst 54 861-867. 

Violent reaction with magnesiiun powders and dusts. Incompatible with aluminiun powders, arsenates, barium, calcium, ethoxy ethynyl alcohols, lead, strong oxidizers, phosphates, strontium, tartrates. MAGNETIC 70 or MAGNETIC 90 or MAGNETIC 95 (7704-34-9) see sulfur. MAGOX (1309-48-4) see magnesium oxide. 

When a strip of magnesium metal is heated in oxygen, it bursts into an intensely white flame and produces a finely powdered dust of magnesium oxide. Write the unbalanced chemical equation for this process. 

At that time, NIOSH also conducted a limited evaluation of the literature and concluded that the documentation cited by OSHA was inadequate to support the proposed PEL (as an 8-hour TWA) of 10 mg/m for the compounds listed below. The current PEL for magnesium oxide fume is 15 mg/m (8-hour TWA, total particulate), and the eurrent PEL for molybdenum (insoluble eompounds as Mo) is 15 mg/m (8-hour TWA, total dust). For the other eompounds listed below the eurrent PEL is 15 mg/m (8-hour TWA, total dust) and 5 mg/m (8-hour TWA, respirable dust). 

Triboadhesive enrichment or beneficiation can be used successfully in two types of applications size classification of powdered materials and the separation of mineral particles from impurities. In the first category we may mention the classification of powders such as quartz, barite, magnetite, hematite, pyrite, feldspar, coal, asbestos, graphite, periclase (crystalline magnesium oxide), pegmatite, and iron ore. As an illustration of an application in the second category we may mention the separation of asbestos fiber ( falling product) from mineral dust that adheres to the drum surface ( retained product) [327]. 

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