Development of a new empirical fragmentation model using rock mass properties, blasthole parameters, and powder factor

• Published in: Arabian journal of geosciences Vol. 13; no. 22
• Main Authors: Moomivand, Hassan, Vandyousefi, Hassan
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2020; Springer Nature B.V
• Subjects: Blasting; Coefficient of variation; Correlation; Earth and Environmental Science; Earth science; Earth Sciences; Empirical analysis; Energy consumption; Fragmentation; Hauling; Image analysis; Image processing; Limestone; Mathematical models; Original Paper; Parameters; Powder; Properties; Properties (attributes); Rock masses; Rocks; Root-mean-square errors; Size distribution; Blastability index; Blasthole parameters; New empirical model; Fragmentation; Powder factor
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-020-06110-2

Rock fragmentation as one of the most important blasting results plays an indispensable role in subsequent stages such as secondary breakage, loading, hauling, crushing and grinding, and relevant energy consumption. Since several rock mass properties, blasthole parameters, and powder factor can affect the fragmentation results, development of an accurate model to predict fragment size has long been a complicated subject. In this study, rock mass properties, blasthole parameters, powder factor ( q ), and fragment size distribution of blasted rock using image analysis technique were determined for several blasting operations in different zones of Sungun open pit copper mine, Rashakan limestone mine, Soufian limestone mine, and Golgohar open pit iron mine. The median fragment size ( X 50 ) varied from 10.4 to 32.1 cm, and the predicted X 50 by the modified Kuz–Ram models was significantly different from the X 50 of the results. Because only a coefficient has been changed from one model to another and the impact of the combination of the parameters on X 50 has not yet been well investigated, the impact of individual essential parameters such as blasthole diameter ( ϕ h ), charge per blasthole ( Q ), rock mass properties, and q on the X 50 , X 80 , and uniformity index ( n ) was originally analyzed to clarify how their combination affects the fragment size of blasted rocks. ϕ h and Q had a similar or a parallel effect on the fragmentation results. Two types of relations between X 50 with the new combination of Q , q , S ANFO , and blastability index (BI) and X 50 with the combination of ϕ h , q , S ANFO , and BI with acceptable correlations were obtained and the correlations also increased when the parameter of joint plane spacing (JPS) was adjusted in the BI system. At the end, a new empirical model was achieved to predict X 50 as a function of combination of Q , q , S ANFO and adjusted BI with higher correlation ( R 2 = 0.865), less root mean square error (RMSE = 3.3 cm), and less coefficient of variation (CV = 19.9%) with actual field results.