This paper presents a brief information about ecologically pure techniques of developing shelf hard mineral extraction. In some cases these techniques are closely connected with well-known ones (dredging) but in most oases the methods in question, as the authors expect, have no analogues. There are presented some technological variants for developing sea beach and sea board placers in closed bays with account for climate conditions and industrial mineral deposit stocks.
According to the appreciated forecasts (Korotkov et al, 1983) the Pacific Ocean Shelf is extremely rich in mineral deposits, which require developing and mastering of modern ecologically pure techniques of their extraction. This raises the problem of lowering harmful effect of rocky waste on natural properties of marine media characterized by the following physical and chemical factors: turbidity (suspended particles), smoothing of the seabed, contamination and toxicity causing perishing of marine inhabitants and disbalance of fishing and fish population zones.
The Department of Mines researchers developed and tested a great number of new methods of extracting hard minerals from the surface of the seabed and at even larger depth (Korotkov et aI, 1983). In the latter case the safety of the work was mainly achieved by the correct choice of safety depth for extracting underwater deposits, the advantage of inviolability of marine flora and fauna being of primary importance. There are presented some technological variants for developing sea beach and sea board placers in closed bays with account for climate conditions and industrial mineral deposit stocks. One of the variants suggested is based on the formation of an ice- or an ice-sand dam in a winter period thus separating the extraction zone from the main water surface. This dam becomes cohesive with the shelf natural ground due to its successive freezing.