Pellets, processing

Other apphcations include dewatering extremely fine (0.1 llm) laterite leach tailings (91). These pelletizing processes should be compared in flocculant consumption and operating and capital costs with belt-filter presses. 

Typical results of the dry pelletizing process when a charge of carbon black and its plus 52-mesh seeds is tumbled in a drum (12) are shown in Figs. 31 and 32. Initially, the seeds grow in size rapidly by snowballing. The dip in the bulk density of the seeds (Fig. 32) suggests that the deposited layers are quite porous in the beginning but get compacted in due course to... 

The task of developing a suitable catalyst for commercial applications involves many considerations, ranging from obvious factors like catalyst activity and selectivity to variables like the catalyst shape and the composition of the binder used in a pelletizing process. This section is devoted to a discussion of these considerations and of the techniques involved in manufacturing industrial catalysts. 

Since fine catalyst particles are desired, the costs associated with the pelleting process are avoided, and it becomes possible to use catalysts that are difficult or impossible to pelletize. 

Yesilada O, Asma D, Cing S (2003) Decolourization of textile dyes by fungal pellets. Process Biochem 38 933-938... 

A commercial pelleting process, used for powdery, lumpy and pasty products, is illustrated in Figure 2.35. 

Table 13.3 Screw Channel Dimensions for the 381 mm Diameter Screw for the PE Flame Retardant Pelletization Process...

Leuenberger H, Luy B, Studer J. New development in the control of a moist agglomeration and pelletization process. STP Pharma 1990 6 303-309. 

Although many types of pellet dosage forms have been introduced in the marketplace, a greater understanding is needed of the role of excipients, equipment, process variables, and controls involved in the pelletization process and those that govern successful scale-up from laboratory to... 

Table II. Effects of Method of Moist Pellet Processing on the Isolation of Mutagenic Residue Organics from Secondary Sludge...

Most expandable polystyrene processes involve aqueous suspension systems in which pentane fractions of petroleum are introduced before, during, or after polymerization of styrene. Water-free systems may also be used. Particle size is controlled by suspension polymerization or by chopping fine filaments. The quenched pellet process for expandable polystyrene can consume off-size particles and is a convenient way to add colorants and cell-nucleating additives. 

The pellets are very uniform in size and shape and are mostly cylindrical. They have a high mechanical strength with a reasonable porosity. To increase the macroporosity one adds e.g. sawdust and (bio)polymers. After the pelletization process the pellets are calcined to burn out the lubricants and other combustible additives. 

The oil furnace process is the most common method of production today and is the source of over 95% of the total output of carbon black globally. In this process, a heavy aromatic fraction of petroleum distillate is atomized and sprayed into a furnace preheated to 1200-1900°C. The feedstock vaporizes and decomposes to form carbon black and combustion gases that are immediately cooled with a series of water sprays and heat exchangers to terminate the carbon black reaction and cool the carbon black product stream. The carbon black is separated from the combustion gases in bag filters and is conveyed for further densification either in pelletization processes or in agitator tanks (from which powdered, fluffy black is collected). 

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