Loosening blasting of rocks at extended delay intervals

The study focuses on loosening blasting of hard rocks and ore at maximum preservation of rock–ore contacts in broken-rock disintegration using special blasting techniques. The commonly used buffer blasting with buffer made of preliminary broken rock requires vast work areas and pays back only in high-value ore production. The simpler and cheaper cushion blasting in the direction from intact rock mass toward operating bench appears to be effective at delay intervals starting from 150–200 ms and longer. Explosion initiation from the middle of a block reduces displacement of broken rocks and preserves nearly natural ore–rock contacts, which allows loosening blasting in long blocks (500 m and longer). Commercial-scale application of blasting patterns with extended delay intervals within 8 years shows that the extended delay intervals have influence on fragmentation and displacement of rocks by blasting: the quality of fragmentation grows and the value of rock shuffle in broken-rock disintegration lowers. Loosening blasting at delay pattern 400×200 ms in the course of 2020, as against the delay pattern 150×200 ms, enabled reduction in ore–rock contact displacement, adjusted after blasthole testing, to 0.8–1.3 m in broken-rock disintegration at loosening factor of 1.3–1.4 and, thereby, allowed improved selectivity of ore extraction by means of decreased ore dilution from 8.8 to 7.6% and reduced loss of useful component by 22%.

Shevkun E. B., Leonenko N. A., Plotnikov A. Yu. Loosening blasting of rocks at extended delay intervals. MIAB. Mining Inf. Anal. Bull. 2021;(12-1):255—263. [In Russ]. DOI: 10.2 5018/0236_1493_2021_121_0_255.

Shevkun E. B., Dr. Sci. (Eng.), Professor, ev.shevkun@yandex.ru, Pasific Nacional Universiti, Russia;
Leonenko N. A., Leading Researcher Mining Institute FEB RAS the separate subdivision of Khabarovsk Federal Research Center of the Far Eastern Branch of the Russian Academy of Sciences, Khabarovsk, Russia;
Plotnikov A. Yu., Deputy Chief Engineer for Drilling and Blasting Operations OOO “AVTAMUR”, Blagoveshchensk, Russia.

Shevkun E. B., e-mail: ev.shevkun@yandex.ru.

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