Handling Dried Material

Planeta-iy Type. Paddles or whips of various configurations are mounted in an off-center head that moves around the central axis of a bowl or vessel. Material is mixed locally and moved inward from the bowl side, causing intermixing. This mixer handles dry materials or pastes. 

Materials handling (dried material too sticky to get out of dryer, causing blockage)... 

Hazard Use a respirator when handling dry material, which evolves toxic fumes of bromine. Strong irritant to eyes and skin. 

As a source of the dust, it is necessary to consider all the various loose building materials (sand, gravel, cement, lime, bricks, etc.). When handling dry material, the dust nuisance is much greater than when handling moist material. Boiler houses and plants for producing bituminous mixture are source of gaseous emissions. 

The copper complex 1s available from Strem Chemicals, Inc., under the name cuprous triflate (benzene complex). The checkers recommend handling the material In a dry box because of Its high moisture and air sensitivity. 

Standard materials for handling dry gases include for chlorine, UNS N10276 (type stainless steel is used for liquid chlorine) for bromine, UNS N10276 (below 60°C) ... 

Spray dryers are normally used for liquid and dilute slurry feeds, but can be designed to handle any material that can be pumped. The material to be dried is atomised in a nozzle, or by a disc-type atomiser, positioned at the top of a vertical cylindrical vessel. Hot air flows up the vessel (in some designs downward) and conveys and dries the droplets. The liquid vaporises rapidly from the droplet surface and open, porous particles are formed. The dried particles are removed in a cyclone separator or bag filter. 

Picric acid, in common with several other polynitrophenols, is an explosive material in its own right and is usually stored as a water-wet paste. Several dust explosions of dry material have been reported [1]. It forms salts with many metals, some of which (lead, mercury, copper or zinc) are rather sensitive to heat, friction or impact. The salts with ammonia and amines, and the molecular complexes with aromatic hydrocarbons, etc. are, in general, not so sensitive [2], Contact of picric acid with concrete floors may form the friction-sensitive calcium salt [3], Contact of molten picric acid with metallic zinc or lead forms the metal picrates which can detonate the acid. Picrates of lead, iron, zinc, nickel, copper, etc. should be considered dangerously sensitive. Dry picric acid has little effect on these metals at ambient temperature. Picric acid of sufficient purity is of the same order of stability as TNT, and is not considered unduly hazardous in regard to sensitivity [4], Details of handling and disposal procedures have been collected and summarised [5],... 

The dry material is extremely sensitive and can be exploded by very light friction. It is too sensitive to handle other than as a solution, or as a dilute slurry in excess solvent, and then only on 1 g scale. 

Sakakura, T. et al., J. Chem. Soc., Perk. Trans. 1, 1994, (3), 283 On two occasions this salt exploded during drying. The dry material is dangerous to handle. In view of the high molecular weight, the diazonium function, alone, represents a low energy per unit mass for explosivity... 

Low-Level Waste Low-level waste (LLW) consists of contaminated dry trash, paper, plastics, protective clothing, organic liquids such as liquid scintillation samples, and the like. LLW is produced by any facility that handles radioactive materials such as nuclear power plants, medical facilities, colleges, and so forth. In the United States, commercial LLW is sent to one of three disposal sites (Barnwell, South Carolina, Richland, Washington, and Clive, Utah). Due to the limited size of these sites (and similar disposal sites through the world) and steeply escalating costs for waste disposal, the primary goal of LLW treatment prior to disposal is volume reduction, either by incineration or compaction, followed... 

The moisture content of the 15 tray-dried batches following final mix remained essentially unchanged from the drying step. The batches from the fluid bed process gained moisture. This is probably attributable to handling very dry material in a relatively humid environment. Both groups are still below the target for this step of 1.5 %, however. 

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