Powdered chemicals, handling

Chemically Synthesized Powders. Chemical synthesis provides a means of produciag powders for manufacturiag advanced ceramics. Disadvantages of chemically synthesized raw materials are expense and difficulties ia scale-up and availabihty. Additionally, ultrafine particle-size powders produced by chemical synthesis pose some unresolved processiag problems ia the areas of handling and mixing. 

The chemist does not think much about how he or she manipulates the mechanics of a process, how chemicals are transported to the site, how they are moved from store to bench, how these often noxious chemicals are moved from their containers and weighed, how they are added to flasks, how the flasks are stirred and heated and cooled, how reflux and distillation are carried out, how and even why solvent recovery is done, how crystals are formed for the best filtration, how filtrations are done and products washed and taken from the filter to a drier and how the drier is operated, how dry powders are handled or offloaded, and how they are milled or micronized. In reality, the differences between the chemist s view of the preparation of a chemical and the chemical engineer s view are profound. In scale-up, the chemist... 

How to Handle Powdered Chemicals and Crystals. If the stopper is hollow, turn the bottle on its side and rotate it with one hand until some of the contents are inside the stopper. Remove the stopper in such a manner that the chemical remains in it, but none falls from the mouth of the bottle. Gently tap the stopper with your index finger until the correct amount has fallen out. Replace the stopper. 

One of the most important material-handling techniques in the chemical industry is the movement of material suspended in a stream of air over horizontal and vertical distances ranging from a few to several hundred feet. Materials ranging from fine powders through 6.35-mm (lA-in) pellets and bulk densities of 16 to more than 3200 kg/m (1 to more than 200 Ib/ft ) can be handled. A large, capable manufacturing... 

The agricultural chemicals in general are more dangerous to handle in solution than in wettable powder or dust form. Parathion and nicotine are the only exceptions to this as they seem to be about equally toxic in wet or dry form. 

In demonstrating the use of powdered aluminium to reduce the oxide in a thermite-type reaction, the mixture must be heated behind a safety screen because of the small explosion produced [1]. Consolidation of the thermite mixture into a high-density composite gives chemical heat sources which are safe to handle [2],... 

Selected aspects of safe practice in solids handling are covered below. For additional information, refer to the rules for plant safety prepared by the Expert Commission for Safety in the Swiss Chemical Industry (ESCIS, 1988). While making no mention of fluidization, this source provides many practical suggestions for the avoidance of electrostatic ignition risks in powder handling operations. 

In the pharmaceutical industry, surface area is becoming more important in the characterization of materials during development, formulation, and manufacturing. The surface area of a solid material provides information about the void spaces on the surfaces of individual particles or aggregates of particles [5], This becomes important because factors such as chemical activity, adsorption, dissolution, and bioavailability of the drug may depend on the surface on the solid [3,5]. Handling properties of materials, such as flowability of a powder, can also be related to particle size and surface area [4],... 

Human life, furthermore, certainly benefits from a less polluted world, and here, again, sol-gel entrapped catalysts are, literally, able to have transferred to within their large inner porosity the whole chemistry of fine chemicals production. Think for instance of an innocuous easily handled orange powder called SiliaCat TEMPO (Chapter 5) that added to a mixture of alcohols at 0 °C with a modest excess of aqueous, cold bleach rapidly converts them into all those fragrances, vitamins, hormones and drugs made of carbonyl compounds. 

---