«Arkhangelskgeoldobycha» JSC (Arkhangelsk, Russia):

Amangusov N. Zh., Chief Geologist of Verkhotinsk Ore Dressing and Processing Enterprise, e-mail: NAmangusov@agd.lukoil.com
Verichev E. M., Deputy Head of Geological Department, Candidate of Geological and Mineralogical Sciences, e-mail: EVerichev@agd.lukoil.com

«Arkhangelskgeolrazvedka» JSC (Arkhangelsk, Russia):

Podlevskikh A. V., Head of Manufacturing Department, e-mail: APodlevskih@agd.lukoil.com

Diamonds occur extremely nonuniform in the crater zone: large, nearly diamond-free layers contain local interbeds, lenses and bonnies with high diamond content. The main objective of the advanced operational exploration is the detection of commercial diamond content areas within the crater zone. Considering the sampling representativity as the essential condition of the exploration procedure, the article presents the elementary diagram of calculating a sample increment for the representative evaluation of diamond content of a size grade. The reference size grade in the diamond content evaluation per sampling in the crater zone is selected the size 16+1 mg. Using the described formula, the authors have calculated the weight of a sample for the representative evaluation of diamond content—511 kg. With sampling at 18-m spacing (an extraction unit thickness), that weight sampling is obtained using core bore not less than 150 mm in diameter. The boring is implemented with the boring rig DeltaBase 540, twin core barrels, with reinforced tungsten-carbide inserts or synthetic diamond bits 210 mm in diameter. The core recovery is 88% at single boring rig advance rate of 500–550 m/month. The samples are processed at the preparation plant located nearby. The processing includes crushing, grinding, classification, screening, jigging and X-ray fluorescent separatio

1. Zuev V. M. Regionalnaya geologiya i metallogeniya – Regional geology and metallogeny, 2005, No.26.
2. Minorin V. E., Grechishnikov D. N., Gorokhov Yu. I., Solopanov A. T. Otsenka i razvedka korennykh mestorozhdeniy almazov (Assessment and exploration of primary diamond deposits). Under the editorship of A. I. Krivtsov. Moscow : Central Scientific-Research Geological Prospecting Institute of Non-Ferrous and Noble Metals, 2000.