Trommel

Trommel is also used in music to refer to a drum.

Portable trommel screening topsoil

A trommel (from the German word for drum, Trommel), also known as a "trommel screen," is a screened cylinder used to separate materials by size - for example, separating the biodegradable fraction of mixed municipal waste or separating different sizes of crushed stone.

Go to "trommel screen" for a major Wikipedia discussion about trommel screens.

Portable trommels (also called portable trommel screens) are often used in the production of organic products from various types of waste.

For example, excavation contractors may screen their site debris into two fractions; a saleable topsoil for farms, nurseries and worksites, as well as cleaned rock for aggregates or landscaping work. This allows the contractor to resell their waste, instead of incurring the cost of sending it for disposal.

The same principle applies to the production of compost, sand/gravel, lumber mill by-products and municipal waste.

Trommels are also used in the recovery of gold from mineral rich soils. The dirt is broken up by high pressure water jets before entering the trommel, which breaks up the dirt further and outputs the rocks and stones while depositing the gold fragments in special plastic mats.