Polar Division, Norilsk Nickel Mining and Metallurgical Company, Norilsk, Russia:

V. P. Marysyuk, Chief Geotechnical Engineer – Director of Center for Geodynamic Safety, Candidate of Engineering Sciences, marysyukvp@nornik.ru
I. A. Ryshkel, First Deputy Director for Mineral Resource

Gipronickel Institute, Saint-Petersburg, Russia

A. V. Trofimov, Head of Center for Physical and Mechanical Research, Candidate of Engineering Sciences
A. P. Kirkin, Junior Researcher

In solving the problems of scientific support of the existing mining production and pre-project development, it is very important to know the properties of the initial rock mass and its characteristics after drilling and blasting. The key property of broken rocks is the particle size distribution. The granulometric composition is characterized by the average particle diameter and the grain size distribution probability described by the distribution law. It is possible to calculate the grain size distribution using methods based on the physical and mechanical properties of rock mass and the parameters of drilling and blasting operations. With the current production, the most accurate data are obtained from instrumental measurements of the particle size distribution. Actual measurements allow calibrating the distribution law and specifying parameters for the preset geological conditions. Under production conditions, the most operational method of instrumental measurement of particle sizes in disintegration of broken rock is photoplanimetry using dedicated software, which is consistent with the best international research practices. This study aimed to determine the granulometric composition of rock mass after preparation for stoping by blasting and to define the most accurate law to describe the grain size distribution. The actual particle size distribution is determined by the photoplanimetric method for large fractions and by the sieve analysis for small particles (less than 70 mm). The modified Weibull and Rosin–Rammler distributions are used as the distribution laws. The results obtained make it possible to predict the grain size distribution by varying blasting parameters with certain limitations on the accuracy of the fine fraction yield.
The authors appreciate participation of Yu. N. Nagovitsyn, P. S. Guzanov, K. E. Breus and A. V. Bazhenov in the study.

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