Particulate feed

Particle size dimension(s) and distribution (surface area) 

Moisture content (free, encapsulated, crystal water) 

Material characteristics (chemistry, density, porosity, plasticity, brittleness, elasticity, wettability, abrasivity) 

Special material characteristics (heat and/or pressure sensitive, toxic, reactive) A.5. Bulk characteristics (temperature, density, flowability) 

Agglomerate size and shape dimension(s), distribution, and tolerance Strength 

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Specification for Particulates Feed, recycle, and product from size reduction operations are defined in terms of the sizes involved. It is also important to have an understanding of the degree of aggregation or agglomeration that exists in the measured distribution. 

Immiscible wetting in mixers Sol-gel processes Pellet flocculation <0.3 Low Up to 10 ton/hr Wet processing based on flocculation properties of particulate feed Coal fines, soot and oil removal from water Metal dicarhide, silica hydrogels Waste sludges and slurries... 

In general, the extent of the ultimate consolidation of the granules and the rate of approach to this limiting value are functions of the size and size distribution of the particulate feed, its density and liquid content, and the... 

Lubricants are often employed to facilitate the uniform transmission of forces and reduce undesirable friction effects during compaction. Lubricants may be classified as internal or external types [2]. Internal lubricants are materials which are added to the particulate feed not only to improve its flow properties (flow into the mold or die and rearrangement during compaction) but also to assist in the release of the final agglomerate from the mold or die. Internal lubricants are generally used in quantities of % to 2%. Internal lubricants, especially when used in excess, may interfere with the optimum cohesion of clean surfaces and reduce the strength of the agglomerates produced. External lubricants are materials used to prevent friction and wear at... 

Liquid or slurry feeds, large artifacts, or continuous sheets and films require completely different equipment to particulate feeds. 

One level of relatively thin tablets or parts with any contour (class I of P/M Figure 187 2) an be pressed with a single punch and force may be applied from one side. The maximum dimension A (Figure 187) depends on the particulate feed and the shape of the compact. Thicker parts (class II of P/M Figure 188), while still requiring only simple tooling, must be pressed from two directions. Holes are obtained by the installation of mandrels or core rods. 

The term bioaccumulation is often used to describe the overall build-up of contaminants within the tissues of an organism. However, sometimes more specific terminology is used to reflect the different routes for absorption of contaminants, with bioconcentration used to denote passive absorption through skin or gills, while bioaccumulation is reserved for ingestion of particulates (feeding) and biomagnification is used to describe the cumulative effects over successive trophic levels in a food chain (Franke et al. 1994). 

However, to obtain uniform pellet quality, minimize pellet length variations, avoid uneven die wear, and ascertain constant power demand, it is necessary to distribute the feed evenly across the entire working width (= perforated area) of the die. Since the particulate feed can only enter the operational area of the machine from the open front of the die ring and, additionally, the interior is to a large extent occupied by the press rollers, this requirement is not easily met. 

While for punch-and-die presses with relatively few strokes per minute (see, for example, Tab. 8.11) accurate and reproducible filling of the die is normally not a problem and the rate of densification in those machines can be adjusted to match the compactibility of the particulate feed, the very high speed of rotary presses often... 

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