Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran:

Hoseinie S. H., Head of the Mining Machinery Laboratory, PhD, hadi.hoseinie@iut.ac.ir
Ghorbani S., PhD Candidate

Division of Operation and Maintenance Engineering, Lulea University of Technology, Lulea, Sweden:
Ghodrat B., Professor

Assessment of rock drillability is an essential stage in selecting the suitable drilling method along with specifying an operation costs and tool wear prediction. Drillability is a complex concept which consist of rock material characteristics, rock mass condition and operational parameters of machine. In this paper, the drillability of ore rock in Razgah Nepheline Syenite mine has been studied to select the suitable drilling method. For this purpose, a stepwise approach is recommended and followed which includes a range of mineralogical, mechanical and physical parameters. During the laboratorial studies which carried on samples collected from bench faces and exploration drilling cores the grain size, grains shape factor and aspect ratio, mineral composition, density, uniaxial compressive strength, Brazilian tensile strength, modulus of elasticity, Schmidt hammer number, Mohs hardness, equivalent quartz content and Schimazek abrasion index were determined based on related ISRM and ASTM standards. The analysis revealed that the studied rock type is classified in moderate strength and abrasive class. In the other hand, considering the scheduled annual production of 1.3 million tones, the borehole diameter is recommended to be six inches. In total, according to laboratorial studies and based on the recommended method for drilling method selection, the down-the-hole (DTH) drilling method is selected as suitable system for studied rock type in Razhag Nefeline Syenite mine. Comparison between the result of presented approach and the past drilling method selection technique reveals that selecting drilling method by focus on mineralogical and hardness values presents more clear result than the past method which considers only uniaxial compressive strength of rock.

The financial support of Isfahan University of Technology and Center of Advanced Mining and Metallurgy (CAMM) at Lulea University of Technology is also acknowledged.

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