Experimental and methodological works were carried out to assess the contents of shallow and fine gold fraction in gale and efele on the sites of dredge poligons Nos. 1, 230, 6, 2 in the valleys of the Uderey and Big Penchenga rivers (south of the Yenisei Ridge).
The granulometric composition of the gold of the original sands, as well as the gold lost in the drains of the efels and gales, was studied by systematic lengthways sampling of the dredge (dredges 1 and 230). With the use of a 7.5" Nelson concentrator at the enrichment of samples, it was established that in the gale and the efele drains of dredges in the valley of the river Uderey (dredges 1, 6) was lost about 30% of gold.
The metal losses left on the rock-floor have been analyzed and evaluated. Recommendations are given to reduce losses and improve the schemes for the enrichment of sands on dredges.