A trommel is a rotating drum with a screen that allows fine material to fall through while retaining larger materials. Trommels are useful in the processing of a wide variety of solids, particles, and mixtures. They come in an assortment of sizes to meet different manufacturing needs and can be used with accessory components to increase functionality, if necessary. Some industries that utilize trommels include the mining, gravel processing, and solid waste management fields.
To operate a trommel, a technician can start an engine that rotates the drum and then add material through an intake chute. It is possible to keep the device in continuous operation by adding more to the chute while the drum processes. As the drum turns, it aerates the materials inside. The smaller particulates fall towards the bottom and out the bottom of the screen, while larger materials work their way toward the opposite end, and eventually out the end and into an exit hopper.
It is possible to use conveyors with a trommel to move the fine and larger particulates. At a facility like a gravel processing plant, rock can move through a series of progressively coarser screens to yield different grades of rock. These can move from very small fill gravel to much larger chunks. Each grade contains rocks within a narrow set of parameters; smaller rocks fell out during earlier processing, while larger rocks were retained and moved along the conveyor.
Another tool some companies may opt to use with a trommel is a pulverizer. Pulverizers crush rock, stone, and other materials into smaller pieces. They can feed crushed materials into a trommel for sorting to generate a continuous supply of rock of a given size. These devices can connect to hoppers that directly load bags or trucks for transport, in settings where a facility processes materials for sale or shipment to other locations.
Mining, rock processing, and similar industries use these devices. They can also be useful in waste management, and on job sites, where workers can set up a portable device. Portability allows workers to sort through the materials they find on side, instead of having to ship them to a remote location. Small sizes typically have weaker motors and may not be able to process high volumes of material, but may be acceptable for basic applications like geotechnical exploration sites where geologists want to process material to determine if the site merits further investigation.