This apparatus may be of the scoop type (single-scoop, with a power-shovel scoop, a grab bucket, or a bucket dragline and multiple-scoop, with an interrupted or continuous scoop chain). Seagoing and continental dredges are distinguished according to their type of power (electric, diesel-electric, diesel, and steam), their means of propulsion (cable-pile or cable-anchor systems), their maximum possible depth of working or extraction (shallow-to 6 m, medium-to 18 m, deep-to 50 m, and extradeep-over 50 m), and the operating principle of the extraction apparatus. Dredges are equipped with washing and concentrating equipment that is mounted on the ship, or they operate on an “extraction-concentration” scheme, sending ore to shore-based or floating concentration installations for processing. These dredges generally are mounted on self-propelled or towed keel ships (less frequently flat-bottomed vessels), ensuring normal flotation and operation in the open sea under storm conditions, in accordance with the requirements of the Marine Register. Seagoing dredges are designed for working placer and sedimentary deposits lying in offshore waters and in deep-water areas of large lakes, seas, and oceans. The former (for working placers on land), as a rule, are mounted on a flat-bottomed pontoon (ship), which ensures normal flotation and operation on a closed body of water, in accordance with the requirements of the River Register of the RSFSR. Dredges are used mainly in working alluvial and eluvial-deluvial placers, as well as offshore and coastal placers, with the exception of boulder varieties, which are strongly cemented by rocks and viscous clays.ĭredges are divided into two categories, continental and seagoing. Specific gravity exceeding 3 (gold, platinum, tin, diamonds, and so on). Rated power of electric motors (kW).ĭisplacement under operating conditiosn (tons). Underwater excavation depth (m).Īverage productivity (m 3/hr). Main technical features of Soviet-produced multiple-scoop dredges (1970) A floating ore-concentration installation with equipment designed for the working of submerged mineral deposits and for the extraction of valuable components with a Table 1.

Dredge up definition