| World Placer Journal - 2003 - Volume 3.
The South Dredge of Shijiir Alt
in the Zaamar Goldfield of Mongolia.
Gerrit R. Bazuin, Robin Grayson & Dr. Baatar Tumenbayar |  INSIDE THE DRAGLINE PERIMETER MOUND...
Panorama of the newer dredging area of the South Dredge. The view is taken from the north section of the perimeter mound, looking south towards the South Dredge in the distance, with its 2 supporting Russian-built Draglines (top left) stripping off more overburden. In the foreground is the mined-out area with the 'ribbed' oversize mound forming a ribbon-like central island. The oversize should be of washed pebbles and boulders, but the photo shows the presence of red Neogene clay balls from the Ulaan Placer and many grey Cretaceous clay balls. (photographer: Robin Grayson) | 
AND WHERE THE DREDGE HAS PASSED EARLIER...
Panorama of the older dredging area of the South Dredge, east (left) of the upper panorama. At this earlier time, the South Dredge ran due north (left to right) and parallel to the Tuul River, preventing the Draglines from creating an outer perimeter wall. Instead, the Draglines had no option but to create an inner perimeter wall visible as the large mound (centre). Only once the dredge path had curved eastwards (to the left) could the Draglines start dumping overburden as an outer perimeter wall. The large mound (centre) sits on valuable placer, and this will compel the operator to put back the material into the dredge pond (middle distance) or to abandon the reserves under the mound as now being sterilised and uneconomic. The use of a Cutter-Suction Dredge to strip off the overburden would have avoided this type of major dilemma. In this part of the old dredge pond, Cretaceous clay is prominent as grey clay balls in the central oversize mound forming the ribbed central island. The imbrication of the ribs indicates that the South Dredge travelled from left to right. (photographer: Robin Grayson) RETURN TO ABSTRACT GO TO NEXT ABSTRACT |
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