Fume characteristics

Fume Characteristics. In commercial blasting, one needs to know what poisonous gases condensed pro diets may be produced and in what proportions they may be found in the atmosphere following a blast. The poisonous gases are referred to in the expl industry as fumes. Limitations of the various methods used to measure fumes (Bichel gauge, Craw-shaw gage Trauzl block) have been recognized for years. The LTSBurMines classification of permissibles into Class A Class B is based on a closed-bomb method... 

Tovex. A series of slurry blasting agents (water gels) manufd by DuPont. They consist of an AN slurry, sensitized with monomethylamine nitrate (MMAN), and with a thickener and cross-linking chemical to promote water resistance. Tovex provides increased safety (thru low hazard and initiation sensitivity), high water resistance, good fume characteristics, and a low propensity for sympathetic detonation... 

Many studies more nearly representative of field conditions have been carried out by various investigators. One important finding was the observation of appreciable undeto-nated expl or expl ingredients in the products of deton. Nitrostarch expls have fume characteristics somewhat better than comparable grades of NG Dynamites, but they do not... 

With the start-up of the new lead smelter in Trail, fume characteristics have changed markedly, and the concentrations of lead, arsenic and other undesirable minor elements have increased while the concentration of zinc decreased through the initial period after the smelter startup. In 1999 a program was initiated to revise the flowsheet to cope with ... 

However, rotary furnaces tend to produce more exhaust gas and fumes, require more skill fill manipulation, and are more labor intensive. Also, the slags produced in the rotary furnaces, soda or fayaUte [13918-37-1] slags, normally do not pass the toxic characteristic leach procedure (TCLP) test and pose a disposal problem. 

These new synthetic mbbers were accessible from potentially low cost raw materials and generated considerable woddwide interest. For a time, it was hoped that the polysulftde mbbers could substitute for natural mbber in automobile tires. Unfortunately, these original polymers were difficult to process, evolved irritating fumes during compounding, and properties such as compression set, extension, and abrasion characteristics were not suitable for this apphcation. 

The melting pot is heated either electrically or by gas to 427—524°C. The pot capacity is typically over 100 kg of lead alloy, and periodically the top of the molten metal must be skimmed to remove the dross. The pot fumes must be removed by adequate ventilation (forced suction). When the molten metal has reached the proper temperature and flow characteristics, it is transported by pump to the grid mold. 

Because of the toxicity associated with lead compounds, governmental rulings have severely limited the use of lead drier in coatings. From a performance viewpoint the use of lead in aluminum paint will destroy the leafing characteristics of the film. Coatings containing lead that are exposed to sulfur fumes will discolor. 

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