Case History: Carbon Granule

A producer of "boutique" carbon wanted a compact system to process raw carbon from production, to make a wide range of product. Some days they might need very coarse granules, sometimes very fine. Impact milling was not practical due to the wide range of finished gradations, but also because occasional tramp metal need to be extracted from the product stream. Impact milling could also break the tramp metal, and potentially cause a spark and a fire.

As with most plants, the headroom was limited, and floor space in limited supply. So, it was desirable to do granule production in as small a space as possible.

Applicon designed and built a unique, compact but serviceable system, including:

• Portable metal bins, to receive hot product and allow cooling "off line". When cool, the product bins are placed by forklift, and the product flows to the processing system.

• Screw feeder, meters the raw carbon to a rare earth magnet, for primary separation of ferrous tramp.

• Inclined shaftless auger, conveys product to crushing. The shaftless spiral eliminates a hanger bearing, and also accommodates the wide range of particle sizes, from very coarse to very fine. A VFD allows this conveyor to also function as a feeder for the mill

• Primary roll mill, with large rolls and deep nip point. Operated at equal speed, with large gap and high speed, this mill will produce coarse granules with less fines. Operated at a small gap, and choke fed, the mill does high compression crushing, to produce mostly fines.

• Scalping screener removes oversize, which are ejected for evaluation prior to disposal or recirculation.

• Finished granular product descends to a bulk bag (IBC) weigh filler.

• Dust collector and fan, with explosion relief panel and vent duct, provide dust control for the entire process. Collected dust is discharged for use as a separate product.

Applicon built the principal processing system as a single skid which could be easily trucked and carried into the plant, and an extension deck to carry the dust collector. Most of the equipment was pre-mounted the two structures, so that site installation, wiring and startup required only a few days.