Washing trommel development

WASHING TROMMEL DEVELOPMENT (EN: drum washing; DE: Spulverfahren; FR: exploitation du placer par lavage, exploitation par injection; ES: explotacion de placeres; RU: буторная разработка) is the process for the primitive development of the placers, using their erosion by the free-flowing water stream, which is passed through the ditch, which is traversing the deposit. While eroding and gradually deepening the ditch, the water carries away the more light-weight waste rock. During this process, the heavy minerals, which should be extracted, are deposited onto the bottom of the ditch, and then are extracted with the help of the washing trommels and troughs. The washing trommel development since the end of the 18th century till the start of the 19th century was the most highly-productive method for the development of the gold-bearing placers. The perfecting of the washing trommel development during the 30-ies of the 19th century at the Urals mountains has enabled the start of the hydraulic method for the development of the deposits. Within the USSR, the washing trommel development works have everywhere been replaced with the mechanized methods for the development: excavator, bulldozer, scraper, hydraulic, dredging.