Satbayev Kazakh National Technical University, Almaty, Kazakhstan:

B. A. Orynbaev, Doctoral Student, baurgud@mail.ru
Kh. A. Yusupov, Professor, Doctor of Engineering Sciences

S. T. Rustemov, Senior Lecturer

Academician Melnikov Institute of Comprehensive Exploitation of Mineral Resources—IPKON, Russian Academy of Sciences, Moscow, Russia:
S. B. Aliev, Senior Researcher, Professor, Doctor of Engineering Sciences, Academician of the National Academy of Sciences of the Republic of Kazakhstan

The substantiation is given support preliminary softening of rock mass to enhance blasting efficiency. The proposed technology was subjected to pilot testing in Ayak-Kodzhan mine, Republic of Kazakhstan. A total of 5 explosions were carried out using the technology with preliminary softening and 5 explosions were executed using the standard technology, with variation in drilling and blasting parameters to determine the optimized drilling and blasting pattern design toward enhanced blasting efficiency. In processing the data of pilot explosions, the dependences of the oversize yield and powder factor on the least burden were obtained using the standard and proposed technologies. Based on the experimental blasting, it can be concluded that the best fragmentation quality is achieved during the first experimental explosion with a drilling pattern 4×4 m and with the use of additional boreholes for preliminary softening of rock mass. The oversize yield is 0.6%. However, during this explosion, the highest powder factor is recorded—1.36 kg/m³. The best economic parameters are obtained in the second experimental explosion with the borehole pattern 4.5×4.5 m. In this case, the oversize yield is 0.8% and the powder factor is 1.05 kg/m³. Moreover, the excavation velocity is increased by 10% as a result. The authors obtain the relationship of the oversize yield and the powder factor with the least burden in the technology with preliminary softening of rock mass. The practical significance of the study lies in the justification of the blasting technology with preliminary rock mass softening and in the optimization of drilling and blasting design to achieve the required fragmentation quality.
The authors express their gratitude to NPP Interrin management represented by CEO P. G. Tambiev for the help and contributory influence during pilot testing.

1. Park J., Kim K. Use of dr illing performance to improve rock-breakage efficien cies: A part of mine-to-mill optimization studies in a hard-rock mine. International Journal of Mining Science and Technology. 2020. Vol. 30, Iss. 2. pp. 179–188.
2. Lapshov A. A., Ermolaev A. I., Manakhov E. D. Justification of optimal delay interval for rock fragmentation in multi-row short-delay blasting. The Ural Mining School–To Regions : The International Science and Industry Symposium Proceedings. Yekaterinburg : Izdatelstvo UGGU, 2010. pp. 201–203.
3. Lizunkin M. V., Lizunkin V. M. Ore extraction parallel converged charges in physical and technical geotechnologies. Inzhenernaya fizika. 2021. No. 11. pp. 31–38.
4. Zhendong Leng, Yong Fan, Qidong Gao, Yingguo Hu. Evaluation and optimization of blasting approaches to reducing ov ersize boulders and toes in open-pit mine. International Journal of Mining Science and Technology. 2020. Vol. 30, Iss. 3. pp. 373–380.
5. Tyupin V. N. Geomechanical behavior of jointed rock mass in the large-scale blast impact zone. Eurasian Mining. 2020. No. 2. pp. 11–14. DOI: 10.17580/em.2020.02.03
6. Rai P., Schunnesson H., Lindqvist P.-A., Kumar U. Measurement-while-drilling technique and its scope in design and pr ediction of rock blasting. International Journal of Mining Science and Technology. 2016. Vol. 26, Iss. 4. pp. 711–719.
7. Kabetenov T., Yusupov Kh. A., Rustemov S. T. Rational Parameters of Blasting, Considering Action Time of Explosion-Generated Pulse. Journal of Mining Science. 2015. Vol. 51, Iss. 2. pp. 261–266.
8. Lyashenko V. I., Khomenko O. E. Enhancement of confined blasting of ore. GIAB. 2019. No. 11. pp. 59–72.
9. Skawina B., Greberg J., Salama A., Gustafson A. The effects of orepass loss on loading, hauling, and dumping operations and production rates in a sublevel caving mine. The Journal of the South African Institute of Mining and Metallurgy. 2018. Vol. 118, No. 4. pp. 409–418.
10. Guanwen Cheng, Congxin Chen, Lianchong Li, Wanchen Zhu, Tianhong Yang et al. Numerical modelling of strata movement at footwall induced by underground mining. International Journal of Rock Mechanics and Mining Sciences. 2018. Vol. 108. pp. 142–156.
11. Mosinets V. N., Abramov A. V. Destruction of fissured and disturbed rocks. Moscow : Nedra, 1982. 248 p.
12. Egemberdiev R. I., Ugolnikov N. V., Yusupov Kh. A. Stolpovskikh I. N. Justification of blasthole expansion parameters in ring blasting. GIAB. 2019. No. 11. pp. 48–58.
13. Smirnov A. A., Baranovskiy K. V., Rozhkov A. A. Method of massive breaking of ore. Innovative Geotechnologies in Metal and Nonmetal Mining : VII International Conference Proceedings. Yekaterinburg : Izdatelstvo UGGU, 2018. pp. 84–89.
14. Sukhanov A. F., Kutuzov B. N. Breakage of Rocks. 2^nd enlarged and revised edition. Moscow : Nedra, 1983. 344 p.
15. Orynbaev B. A., Yusupov Kh. A. Improving the efficiency of breaking with the creation of prestress in the array. Journal of Advanced Research in Natural Science. 2021. No. 13. pp. 36–45.
16. Rodionov V. N., Sizov I. A., Tsvetkov V. M. Basic geomechanics. Moscow : Nedra, 1986. 301 p.
17. Komashchenko V. I., Noskov V. F., Ismailov T. T. Blasting : Textbook. Moscow : Vysshaya shkola, 2007. 439 p.