Investigation of blast design parameters from the point of seismic signals

The results of blasting affect every other downstream operation in quarrying and mining process. Factors influencing blast results can be classified as either controllable or non-controllable. If desired fragmentation is to be obtained, the controllable factors (blast geometry and explosive properties) must be sufficiently designed to match the non-controllable ones (geological factors and legislative constraints). This study investigates the influence of blast design parameters on rock fragmentation. Six different blast designs were studied and analyzed. Rock samples were obtained from each face to evaluate the uniaxial compressive strength (UCS). Images of muck pile were captured using suitable digital camera. The images were uploaded into the WipFrag software to analyze the fragmentation resulting from the blasting. The particle size distribution of each blast was obtained, and the mean fragment size correlated with the blast design parameters. The percentage cumulative passing for gyratory crusher with the feed size of 1500 mm ranges between 92.8 to 100%. The stiffness ratio, powder factor and uniaxial compressive strength have high correlation with mean fragment size. The stiffness ratio increases with mean fragment size with a correlation coefficient of 0.89. The mean fragment size becomes finer with increase in powder factor with a correlation coefficient of 0.76. Powder factor also has a high correlation with the uniaxial compressive strength of the rock. The higher the uniaxial compressive strength of rock, the higher the powder factor needed for a specified fragment size. In this study, spacing to burden ratio has a very weak correlation with the fragment size. All the studied blast events produced good fragmentation with a uniformity index varying from 2.097 to 2.525.

Download Full-text

Comparison of the existing and calculated blast design parameters for the rock mass conditions at Bamesso-Latet rock quarry

Journal of Nepal Geological Society ◽

10.3126/jngs.v60i0.31273 ◽

2020 ◽

Vol 60 ◽

pp. 131-137

Author(s):

Safianou Ousmanou ◽

Ndapeh Nd. Blaise ◽

Fozing Eric Martial

Keyword(s):

Cost Effective ◽

Practical Method ◽

Design Parameters ◽

Mining Engineering ◽

Break Rock ◽

Blast Design ◽

Good Production ◽

Blast Fragmentation ◽

Minimal Damage

Blasting is the most cost effective methodology to break rock for mining engineering applications. A good production blast will break only the rock that is needed to be removed, leaving the host rock with minimal damage. Accurate measurement of blast, fragmentation is important in mining and quarrying operations, in monitoring and optimizing their design. Currently, there are several methods available to predict damage due to blasting. The accuracy of many of these methods is questionable, and in most cases, the methodologies over predict the results. This paper presents a practical method (i.e. Langefors’s method) that we shall use in Bamesso-Latet rock quarry to do a comparison between the existing and calculated blast design parameters. The proposed method allows to assess the rock damage from blasting. It shows great potential as a practical aid to control and get a good quality of the fragmented material in Bamesso-Latet rock quarry.

Download Full-text

Development of a New Blast Vibration Prediction Model Incorporating Burden Variations in Surface Blasting

Geotechnical Applications for Earthquake Engineering ◽

10.4018/978-1-4666-0915-0.ch010 ◽

2012 ◽

pp. 171-187

Author(s):

M. Ramulu

Keyword(s):

Vibration Monitoring ◽

Design Parameters ◽

Rock Fracturing ◽

Blast Vibration ◽

Vibration Intensity ◽

Blast Design ◽

Vibration Prediction ◽

The Common ◽

Predictor Model ◽

Quantitative Explanation

The globally followed common vibration predictor model includes distance from source to vibration monitoring location and quantity of explosive charge per delay without giving much consideration to blast design parameters. Though there are qualitative assertions on the influence of burden on the vibration intensity by many researchers, no work on quantification of influence of burden has been reported. This paper deals with the development of a predictor model incorporating burden deviations in the existing predictor equation. The influence of burden on the vibration was viewed from the angle of detonation and rock fracturing during blasting. The new predictor equation is based on existing models developed by other researchers on the influence of burden on the blasthole pressure and vibration intensity as well as on some logical assumptions. The influence of burden on vibration was examined in two independent phases of blasting, and the net effect was calculated by adding the influence in both the phases. The study provides a quantitative explanation for the common observations of increased vibration levels produced by the blast rounds with excess burden and/or misfired shots.

Download Full-text

Prediction and Assessment of Back Break by Multivariate Regression Analysis, and Random Forest algorithm in hot strata/fiery seam of open-pit coal mine

10.21203/rs.3.rs-267513/v1 ◽

2021 ◽

Author(s):

Mukul Sharma ◽

Bhanwar Singh Choudhary ◽

Hemant Agrawal

Keyword(s):

Regression Analysis ◽

Random Forest ◽

Coal Seam ◽

Coal Mine ◽

Multivariate Regression ◽

Multivariate Regression Analysis ◽

Open Pit ◽

Design Parameters ◽

Random Forest Algorithm ◽

Blast Design

Abstract Coal seam in mines sometimes catches fire due to its property of spontaneous heating. Drilling and blasting techniques are the most economical operation for the removal of overburden and extraction of coal in an open-pit coal mine. Blasting in a fiery seam is one the most dangerous and risky operations and various environmental and technical problems are associated with it. While blasting in a fiery coal seam, it is essential to use the minimum amount of explosive in a hole and the blast should be taken quickly. As the amount of explosive to be used must be comparatively lesser; therefore, it becomes important to perform the blasting in a manner to maximize the utilization of explosive energy. Improper utilization of energy causes back break, which is one of the technical concerns for management due to the in-stability of high wall. This study is a unique attempt to predict back break, especially in fiery coal seam through the experimental blasts and their analysis by Multivariate Regression Analysis (MVRA), and Random Forest algorithm (RFA). Total 26 blasting were conducted at open pit mine. To obtain the most optimum blast design parameter, blast design parameters were varied. The observed back break during trial blasts varies from 1.4 to 10 m. The Sensitivity analysis performed with the collected data and it has been found that stiffness ratio and stemming length are the most influential parameters on generation of back break. The MVRA and RFA analysis have been adopted for accurate prediction of back break. The results show that the RFA analysis predicts the backbreak and achieved the RMSE of ± 0.59 m while in MVRA, RMSE achieved was ± 0.99 m, making RFA more suitable method to be used for backbreak prediction in fiery seam blasting.

Download Full-text