Roll Compacting and Briquetting

TABLE 12.13. Moisture Requirements for Successful Granulation in Tumbling Machines 

Raw material Approximate size analyses of raw material, less than indicated mesh Moisture content of balled product (% HJO) 

Dish size (m) Motor (kWj Capacity (kg Material Remarks 

076 Bituminous coal filter cake Feed to pan dryer 

59 11 8.5 Zinc concentrate sinter mix Micropelletized sinter machine feed 

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Roll compacting and briquetting is done with rolls ranging from 130 mm dia by 50 mm wide to 910 mm dia by 550 mm wide. Extrudates are made 1-10 mm thick and are broken down to size for any needed processing such as feed to tabletting machines or to dryers. 

Fig. 5.2. Schematic diagram of a roll compaction and briquetting press [13].

Roll Compacting and Briquetting 354 Tabletting 357 Extrusion Processes 358 Prilling 361... 

Figure 12.10. Equipment for compacting, briquetting, and pelleting, (a) Flowsketch of a process for compacting fine powders, then granulating the mass (Allis-Chahners Co.), (b) Integrated equipment for roll compacting and granulating (Fitzpatrick Co.), (c) A type of briquetting rolls, (d) A gear pelleter. (e) A double roll extruder.

Powder compaction may also be achieved in roll processes, including briquetting, in which compression takes place between two rollers rotating at the same speed—that is without producing any shearing action. In pellet mills, a moist feed is forced through die holes where the resistance force is attributable to the friction between the powder and the walls of the dies. 

Sheskey, P.J. Hendren, J. The effects of roll compaction equipment variables, granulation technique, and HPMC polymer level on a controlled-release matrix model drug formulation. Pharm. Technol. 1999, 23 (3), 90-106. Johanson, J.R. Roll Press Feed Systems. Proceedings of the 24th Institute for Briquetting and Agglomeration, October 1995 Vol. 24, 149-163. 

Another modular system is often called laboratory equipment it can be used for small scale production and for the laboratory evaluation of small samples. Fig. 11.26 depicts the design and some of the accessories. In the most simple execution a hopper feeds a pair of rollers which are driven by a hand crank. The rollers can be solid and may be equipped with compacting or briquetting surfaces (see Section 8.4.3) or two perforated, geared, intermeshing pelleting rolls (see Section 8.4.2) are installed to accomplish medium pressure extrusion. In a modular fashion the rollers can be motorized, screw feeders can be added, and the rolls may be oriented vertical or horizontal or in any other direction. As shown in the photographs of Fig. 11.27 the roller frame can be totally enclosed for dust control if toxic or hazardous materials are processed. A panel includes controls and instrumentation for data display and collection. 

The importance of roll design for roll-type briquetting, compacting, and pelleting machines as defined by their technical application.)... 

Fluffy spray-dried material can be compacted into articles having a larger particle size and higher bulk density by the application of mechanical pressure or force. The compaction can be accomplished by known means such as tabletting presses and briquetting machines, but preferably by passing the powder between rotating rolls. 

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