Page 395 - Chemical Process Equipment - Selection and Design

358 DISINTEGRATION, AGGLOMERATION, AND SIZE SEPARATION OF PARTICULATE SOLIDS

Collects virgin and
Vertical Screw + i ’- Upper Feed Hopper
Pre-compresses recycle product
and deaerateslproduct FHorizonlal Feed Screw
Controlled feed
Pressure Applied
Air to hydraulic
actuator regulates
exerted on rolls ~
Breaks sheets
into chips and flakes
-Feed and
Recycle

Fine material Screen Oversize and fines
,---+-n U A Sizes compacted
material lo desired
Granulator
particle size Lfreener

Overs
Oversized

Finished Recycle J
Product
flowing dustless
controlled
Darticle size

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

breaking them into coarse granules, or by batch-fluidized bed tablets are 10 tons, but up to 100 tons may be needed for tablets
granulation. For pharmaceuticals the range of allowable additives to 2.5-4 in. dia. The largest machines shown can be driven with about
facilitate tabletting is limited. Magnesium stearate is a common 50 HP.
lubricant to the extent of 0-2%, and corn starch is a common
binder in the range of 0-5%. Disintegrants and fillers also are used.
Preparation of such mixes is accomplished in powder blenders and EXTRUS,ON PROCESSES
fixed by granulation. Powders, pastes and melts are pelleted by extrusion through a die
The Stokes machines of Figure 12.8 operate at 35-100 rpm and followed by cutting. Binders and lubricants may need to be
the large Manesty at 45-180 rpm. Maximum forces for these sizes of incorporated in the feed, but the process usually is not feasible for