Blastability Index Research Articles

Backpropagation-based inference for spatial interpolation to estimate the blastability index in an open pit mine

The blastability index (BI) is a measure that indicates the resistance of rock to fragmentation when blasting. With novel technologies, miners are now able to collect and calculate BI at different depths while drilling. In this research, we propose an approach to estimate the BI at multiple depths for new areas using only spatial locations and observed BI measurements of previously drilled holes. Spatial interpolation techniques are investigated. This study introduces a novel treatment for Gaussian Processes (GPs) and Inverse Distance Weighting (IDW). Variography is leveraged to ensure an appropriate fit between the data and the spatial component. The parameters controlling anisotropy are constrained to intervals chosen to reflect the observed anisotropy. Gradient descent with back-propagation is used for optimization. The proposed approach improves the performance of GP and IDW at predicting BI. The similarities between the IDW variant proposed and a single-layer neural network are discussed.

Development a novel empirical approach to control overbreak, surface quality and slope angle of benches following blasting

Overbreak, slope angle and quality of a bench behind the boundary of excavation as attractive subjects for mining and civil engineers are the most crucial consequences of the post-blast. But the breakage mechanism of blasting has not originally been well clarified how a desirable slope angle and quality of a bench can be obtained by common drilling and blasting operations and what parameters can affect such blasting consequences? The breakage mechanism and influence of the blasthole parameters such as hole diameters, explosive weight per hole, burden, spacing, stemming, bench height, powder factor and blastability index on the depth of the overbreak zone (L<sub>OZ</sub>), the difference between hole and bench slope angles (α°-β°) and the width of damaged zone (L<sub>DZ</sub>) in fifteen zones of Sun gun open pit copper mine, Golgohar open pit iron ore mine, Khoy limestone, Rashakan limestone, Bonab silica mine and Evoghli gypsum mine were investigated. New multivariable nonlinear relations between each of L<sub>OZ</sub>, (α°-β°) and L<sub>DZ</sub> with the combination of Φ<sub>h</sub>, Q, B, S, S<sub>t</sub> and K were developed. The new achievements in this study can be new guides to obtain the desirable bench slope angle and bench faces.

Validity of the NTNU Prediction Model for D&B Tunnelling

AbstractThe Norwegian University of Science and Technology (NTNU) has since the early 1970s published prediction models for estimated production rates, time consumption, and costs for rock works. Since the early development of the NTNU models the tunnelling industry has continuously improved and the models have been updated on several occasions. The NTNU models are presently being updated to better fit the modern tunnelling trends in Norway. The current prediction model for D&B blast design is in this research paper compared with new data from thirteen recent Norwegian tunnel projects. The paper demonstrates that the empirical methodology behind the prediction model is still highly relevant, but some further improvements and additional empirical relations are suggested to enable the model to better cope with the recent 16 years of development in technology, equipment, contractual-issues and blast design. The new datasets show that modern D&B tunnelling employ more drill holes and specific charging per blast round than before. The current NTNU model thus under-predicts the actual tunnelling performance in the blast design. Some suggestions are made for further improving the model, where the updated drill length, the contour requirements, and the tendency to including the longitudinal ditches into the main blast are suggested as the main reasons for the disparity in drill hole numbers. Yet, the current trend in specific charging seem to have doubled since the early 2000s and cannot be explained by the increase in drill holes alone. Further development ought to be included in the blastability index (SPR) so that geological conditions that are on the extreme side of poor blastability can be properly accounted for in the blast design.

Development of site specific blasting index parameters based on single hole blast test cratering

ABSTRACT An experimental method is proposed to assess blasting requirements based on in-situ cratering behavior. The method relies on single hole blast (SHB) tests to derive burden-dependent relationships. A non-linear crater model of the form is calibrated from SHB test results to describe the cratering behavior. Parameters and represent characteristic blastability index parameters that depend on geomechanical and operational conditions. A series of experimental SHB tests were conducted at three hard rock mines. The craters were mapped to capture the breakout profile and calibrate the model. Results showed that coefficient presents an inverse linear correlation with burden , while exponent s is approximately constant for a considerable range of burden values. Experimental results are used to define burden dependent relationship for bench blast designs and blasthole placement in underground development rounds. A complementary analysis addresses the prevalence of multiple cratering mechanisms according to geology and burden dimension.

Effects of Blast Design to the Environment in Limestone Quarry

The demand for construction materials produced by quarry rises in tandem with urbanization. The enormous number of complaints, however, has put the quarry owner under constant pressure to ensure safe blasting operations and minimal blasting effect on the environment. Due to the fact that limestone naturally dissolves in water and creates numerous weak spots in rock masses, it has always been thought that limestone quarry operations are more risky than common granite quarry operations. The goal of the study was to identify the rock mass properties of limestone and how they related to the consequences of blasting operations. For a systematic study, the quarry face was divided into four (4) Sections i.e., Section A, Section B, Section C, and Section D. The preliminary study was involved site investigation for quarry face evaluation and data collection as well as results from blast monitoring program for two months in a row was also recorded. The analysis was started with calculation of Blastability Index (BI) of the study area based on rock mass properties data and Blastability Quality System (BQS). The new predicted site constant (rock mass properties), κ and β were calculated based on two globally recognized empirical equations i.e., USBM and Langefors-Kihlstrom and the results was employed as indicator for future blasting operations. The SPSS Regression Model analysis graphs shown USBM predictor was inversely proportional to the PPV, while, the Langefors-Kihlstrom predictor graph was proportional to the PPV. The calculated K and β values for USBM predictor was 40 and 1.0 respectively. Based on the analysis, the rock mass properties at this limestone quarry have high influence to blasting effects and the effect can be aggravated at certain study sections. From all sections, Section A was deemed the most sensitive area or has the highest risk of generating excessive environmental effect with the lowest BI value (higher rock strength) at 49.18%, located closest to sensitive public buildings and recorded the most joint sets. It is can be concluded that the blasting activities in this quarry although at maximum charge per delay (Wmax) was being carried out safely with very minimal effects to the surrounding areas and in accordance to the limits set by the relevant authorities i.e., JMG and DOE Malaysia.

Estimating Flyrock Distance Induced Due to Mine Blasting by Extreme Learning Machine Coupled with an Equilibrium Optimizer

Blasting is essential for breaking hard rock in opencast mines and tunneling projects. It creates an adverse impact on flyrock. Thus, it is essential to forecast flyrock to minimize the environmental effects. The objective of this study is to forecast/estimate the amount of flyrock produced during blasting by applying three creative composite intelligent models: equilibrium optimizer-coupled extreme learning machine (EO-ELM), particle swarm optimization-based extreme learning machine (PSO-ELM), and particle swarm optimization-artificial neural network (PSO-ANN). To obtain a successful conclusion, we considered 114 blasting data parameters consisting of eight inputs (hole diameter, burden, stemming length, rock density, charge-per-meter, powder factor (PF), blastability index (BI), and weathering index), and one output parameter (flyrock distance). We then compared the results of different models using seven different performance indices. Every predictive model accomplished the results comparable with the measured values of flyrock. To show the effectiveness of the developed EO-ELM, the result from each model run 10-times is compared. The average result shows that the EO-ELM model in testing (R2 = 0.97, RMSE = 32.14, MAE = 19.78, MAPE = 20.37, NSE = 0.93, VAF = 93.97, A20 = 0.57) achieved a better performance as compared to the PSO-ANN model (R2 = 0.87, RMSE = 64.44, MAE = 36.02, MAPE = 29.96, NSE = 0.72, VAF = 74.72, A20 = 0.33) and PSO-ELM model (R2 = 0.88, RMSE = 48.55, MAE = 26.97, MAPE = 26.71, NSE = 0.84, VAF = 84.84, A20 = 0.51). Further, a non-parametric test is performed to assess the performance of these three models developed. It shows that the EO-ELM performed better in the prediction of flyrock compared to PSO-ELM and PSO-ANN. We did sensitivity analysis by introducing a new parameter, WI. Input parameters, PF and BI, showed the highest sensitivity with 0.98 each.

Analysis of explosive energy distribution at Pit 7 West PT. Makmur Mandiri Utama Binungan Suaran - Berau, East Kalimantan Province

Blasting geometry and blasting material filling are closely related to the rock mass characteristics and the geological conditions to obtain ideal fragmentation. Blastability Index analysis, including Description of Rock Mass, Combined Plane Spacing, Combined Plane Orientation, Specific Gravity Influencey, and Hardness, are the alternative geometry experiment conducted to overcome the problem of rock fragmentation so that the speed of excavation equipment can increase according to the productivity of Komatsu PC2000 plan at PT. BUMA Jobsite BINSUA. Furthermore, the actual rock values obtained from blasting location and alternative geometry recommendations using R.L.Ash theory combined with Vertical Energy Distribution theory. In the C2 layer with a rock factor value of 5.95, the recommended load is 7.2 m, space is 8.3 m, and the VED explosive power is 48%. In layer D2 the rock factor value is 6.89 with a load of 7.5 m, space of 8.3 m, and 55% VED explosive charge. While in the DU layer, the rock factor value is 6.39 with a load of 7.3 m, 8.4 m space, and 51% VED filling of explosives. Prediction of blasting fragmentation analysis using Kuz-ram theory obtained fragmentation > 100 cm, namely 14.99% for the C2 layer, 14.84% for the D2 layer, and 14.82% for the DU layer.

Perencanaan Design Geometri Peledakan Berdasarkan Karakteristik Massa Batuan di Bench M PT Tanjung Bukit Nunggal Kabupaten Bangka Tengah

The availability of the discontinuity structure causes the rock to be blown up have a cavity that later can be traversed by the thumping of explosive energy, so force from the explosion will be inhibited and the blasting is not optimal. This study aims to find the physical condition of granite rock at the mining site, find out the value of Blastibality Index of rock, and analyze the geometry design of blasting to obtain fragmentation ≤ 75 cm. The methods used in this study are quantitative and qualitative methods that are measuring joint structures, physical conditions of rocks, calculation of Rock Factor (RF) values, and calculation of Blastibility Index. The results of this study show if the physical condition of the rocks on bench M has an RQD value 88.97 % - 99.66 %, and Rock Factor value 5.51 and a Blastability Index 45.9 so, obtained a design of geometry with a burden 3.4 m, spacing 5.1 m, stemming 2.55 m, subdrilling 0.68 m, height 7.62 m, depth 5.1 m, and power charging 2.55 m.

Uncertainty consideration in rock mass blastability assessment in open pit mines using Monte Carlo simulation

Blastability is defined as the resistance of rock mass to fragmentation due to the dynamic stress of blasting. Comprehensive study and understanding of geomechanical conditions of the in-situ rock mass are necessary to analyze the blastability along with optimal blasting design. Blastability Index (BI) is one of the most widely applied methods for the classification of rock mass and predicting the specific charge of blasting in open pit mines. Regarding the existence of uncertainty in the geomechanical characteristics of in-situ rock masses, accurate BI assessment requires a wide range of field studies. It could lead designers to a wrong decision about rock mass classification. Simulation is one of the reliable and applicable approaches to overcome the geomechanical uncertainties in rock mass studies. Therefore, in this paper, the Monte Carlo simulation method has been applied to blastability assessment in Sungun Copper Mine, Iran. For this purpose, the geological factors, including rock mass description, joint plane spacing, joint plane orientation, specific gravity influence, and hardness, were measured and implemented in 46 points of the pit wall. Statistical analysis was carried out to find out the best fit-distribution functions of all mentioned parameters. After that, the Monte Carlo simulation program was developed and carried out in MATLAB software. The overall results of the simulation reveal that the Monte Carlo method could provide a better vision of any possible combination of geological factors. It is also found out that less than two percent of the rock masses do have challenging blastability conditions, and the average blastability of rock masses in the studied mine is 18, which is close to an average score of blastability classification as well.

A New Approach to Represent Impact of Discontinuity Spacing and Rock Mass Description on the Median Fragment Size of Blasted Rocks Using Image Analysis of Rock Mass

Several in-situ rock mass properties and blasthole parameters can affect the rock fragmentation. Because of the complexity of the variables affecting the fragmentation results of blasted rocks, to predict a proper value of the median fragment size has long been a difficult task. The blastability index (BI) represents the effect of five parameters of rock mass description (RMD), joint plane spacing (JPS), joint plane orientation, specific gravity and uniaxial compressive strength on the rock fragmentation. The median discontinuity spacing significantly varies with varying the scanline direction and an acceptable value of the median discontinuity spacing will not be expected in practice. The JPS rating also has a constant value of 20 for a wide range of joint spacing values between 0.1 and 1 m, whereas joint spacing can be in this range for most cases. A new method using image analysis of the in-situ rock mass was applied to represent JPS and RMD (belonging to one of the cases: friable, blocky and massive) as an alternative solution. The images contain the details of all individual discontinuities and interlocked in-situ small and large rock blocks. BI, rock strength factor, blasthole parameters, powder factor, fragment size distribution of blasted rock and in-situ block size distribution using image analysis technique were assessed in 15 zones of Sungun open pit copper mine, Angouran lead and zinc open pit mine, Bonab silica mine, Soufian limestone mine and Rashakan limestone mine. The results for rock mass properties and blasthole patterns cover a wide range using different mines. The fragment size distribution was assessed by Split Desktop program with proper delineating images using the Pixler software and blasting was carried out with electric delay detonators. The relations between fragment size and parameters such as in-situ block size (F50), σc, rating of joint plane orientation, powder factor (q), ϕh, Q and Lc were analyzed. The relations with high correlations were achieved by applying the new approach for the defined conditions. Not only the problem of assessing discontinuity spacing has been improved using this method but also the lower number of parameters that properly represent the factors affecting the rock fragmentation have been used. The results were also analyzed by the Sanchidrian and Ouchterlony model and modified Kuz–Ram models. The fragment size obtained by the new method in this study, Sanchidrian and Ouchterlony model and extended modified Kuz–Ram model by Cunningham (in: Proceedings of 3rd world conference on explosives and blasting, Brighton, 2005) after using correction factor [c(A)] significantly better fitted to the results than the modified Kuz–Ram models by Cunningham (in: Fourney, Dick (eds) Proceedings of 2nd international symposium on rock fragmentation by blasting, Keystone, 1987) and Gheibie et al. (Int J Rock Mech Min 46(6):967–973, 2009).

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

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 (X50) varied from 10.4 to 32.1 cm, and the predicted X50 by the modified Kuz–Ram models was significantly different from the X50 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 X50 has not yet been well investigated, the impact of individual essential parameters such as blasthole diameter (ϕh), charge per blasthole (Q), rock mass properties, and q on the X50, X80, and uniformity index (n) was originally analyzed to clarify how their combination affects the fragment size of blasted rocks. ϕh and Q had a similar or a parallel effect on the fragmentation results. Two types of relations between X50 with the new combination of Q, q, SANFO, and blastability index (BI) and X50 with the combination of ϕh, q, SANFO, 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 X50 as a function of combination of Q, q, SANFO and adjusted BI with higher correlation (R2 = 0.865), less root mean square error (RMSE = 3.3 cm), and less coefficient of variation (CV = 19.9%) with actual field results.

Blast Design for Improved Productivity using a Modified Available Energy Method

In this work, a new drilling and blasting design methodology is introduced and applied at a case study mine to improve productivity. For the case study copper mine, a blast diameter of 203 mm is proposed to be used in the ore zone to meet the new required production rate of 90mtpa from 75mtpa. Currently, the Konya and Walter’s model is used to generate drilling and blasting design at a blasthole diameter of 172 mm. The new drilling and blast design approach is advantageous in the sense that it generates a lower specific drilling value and predicts an average fragment size compared with the current method being used. In this regard, a modified available energy blast design method that incorporates the blastability index of ore zone in the calculation of the input powder factor is introduced. The results of the blast design simulations at a 203 mm blasthole diameter shows that the modified available energy model generates a drilling and blasting design with a specific drilling value that is 15.3% less than that generated by the Ash’s and Konya and Walter’s models. Further, the modified available energy model generates a blast design with a predicted average fragment size that is 3.4% smaller than that generated by the Ash’s model, and 6.7% smaller than that generated by the Konya and Walter’s model.

Development of a New Model to Predict Uniformity Index of Fragment Size Distribution Based on the Blasthole Parameters and Blastability Index

Development of a New Model to Predict Uniformity Index of Fragment Size Distribution Based on the Blasthole Parameters and Blastability Index

Development of a New Model to Predict Uniformity Index of Fragment Size Distribution Based on the Blasthole Parameters and Blastability Index

Uniformity index n represents the range of fragment size distribution and it is applied to evaluate fragment size by Rosin and Rammler cumulative distribution function for a muck pile. The uniformity index n of fragment size distribution has been assessed by digital image analysis technique using Split-Desktop for several blasthole parameters and different zones of in-situ rock mass conditions in five mines having a wide range of blastabilty index (BI). Rosin and Rammler equation has been determined by a new procedure using a software entitled Pixler to delineate images the same as manual method for achieving a proper fragment size distribution by Split-Desktop. The obtained values of n had significant differences with estimated n by the former equations. Relations between n and several blasthole parameters, BI and mean fragment size X50 of the results and their various combinations have been analyzed. Finally, a new empirical model having a good correlation has been developed to predict n value for using 25 ms electric delay detonators.

Application of rock mass classification and Blastability Index for the improvement of wall control: a hard-rock mining case study

Application of rock mass classification and Blastability Index for the improvement of wall control: a hard-rock mining case study

Predicting the average size of blasted rocks in aggregate quarries using artificial neural networks

The prediction of the average size of fragments in blasted rock piles produced after blasting in aggregate quarries is essential for decresing the cost of crushing and secondary breaking. There are several conventional and advanced processes to estimate the size of blasted rocks. Among these, the empirical prediction of the expected fragmentation in most cases is carried out by Kuznetsov’s equation (Sov Min Sci 9:144–148, 1973), modified by Lilly (1986) and Cunningham (1987). The present research focuses on the effect of the engineering geological factors and blasting process on the blasted fragments using a more powerful, advanced computational tool, an artificial neural network. In particular, the blast database consists of the blastability index of limestone on the pit face, the quantities of the explosives and of the blasted rock pile, assessing the interaction of these parameters on the blasted rocks. The data were collected from two aggregate quarries, Drymos and Tagarades, near Thessaloniki, in the Central Macedonia region of Greece. This approach indicates significant performance stability, providing the fragmentation size with high accuracy.

An Application of Fuzzy Sets to the Blastability Index (BI) Used in Rock Engineering

Rock masses have inherently different resistance to fragmentation by blasting. This property is hereafter referred to as the blastability of a rock mass. Empirical models for the estimation of blastability have been developed. In this study, the Mamdani fuzzy algorithm was used to express the blastability index by fuzzy sets. We use Lilly and Ghose blastability models which are important models of blastability. Parameters of these models were represented by fuzzy sets as the input variables of the fuzzy model. The output of the fuzzy model is a final blastability index rating. Experimental data is obtained from seven mine and one dam sites in Iran. BI values are obtained from both BI fuzzy inference system and conventional BI; Fuzzy sets have more adjustment than conventional model.

Application of PCA, SVR, and ANFIS for modeling of rock fragmentation

Fragmentation has direct effects not only on the drilling and blasting costs but also on the economy of subsequent operations. In the present study, two soft computing-based models, so called “support vector machines (SVM)” and “adaptive neuro-fuzzy inference system (ANFIS)” were used and compared with Kuz-Ram method. In this regard, six effective parameters including specific charge, stemming length, total delays per number of rows ratio, hole diameter, spacing to burden ratio, and blastability index were considered as input parameters containing a database of 80 variables from the blasting operation of the Chadormalu iron mine of Iran. Principal component analysis (PCA) was performed to clarify the effective parameters on the fragmentation. As statistical indices, root mean square error (RMSE), correlation coefficient (R 2), bias, variance account for (VAF), and mean absolute percentage error (MAPE) were used to evaluate the efficiency of the addressed models between measured and predicted values of rock fragmentation. The results confirmed the ANFIS and SVM as accurate predictive tools for rock fragmentation in open-pit mines. Correlation coefficient, bias, VAF, and MAPE generated by the ANFIS model (respectively 0.89, 0.257, 88.19, and 10.37) were higher than referred values for the SVM model (0.83, 1.87, 75.24, and 16.25, respectively) as well as Kuz-Ram inference.

Blastability Quality System (BQS) for using it, in bedrock excavation

Success in the excavation of foundations is commonly known as being very important in asserting stability. Furthermore, when the subjected formation is rocky and the use of explores is required, the demands of successful blasting are multiplied. The quick and correct estimation of excavation's characteristics may help the design of building structures, increasing their safety. The present paper proposes a new classification system which connects blastability and rock mass quality. This new system primarily concerns poor and friable rock mass, heavily broken with mixture of angular and rounded rock pieces. However, it should concern medium and good quality rock mass. The Blastability Quality System (BQS) can be an easy and widely - used tool as it is a quick calculator for blastability index (BI) and rock mass quality. Taking into account the research calculations and the parameters of BQS, what has been at question in this paper is the effect of BI magnitude on a geological structure.

Rock mass blastability dependence on rock mass quality.

The present paper tries to investigate the influence of rock mass quality characteristics on blasting results. In order to come to some conclusions, blastability and quality of rock mass were put together using the already known classification systems. Taking into account the quantity of blastability index (BI) for every possible structural appearance of the poor rock mass, the relation of discontinuities characteristics and blastability index are investigated. The estimations of the above trial gave arise on a new classification system being called “Blastability Quality System (BQS)”, which can be an easily and wide use tool as it is a quickly calculator for blastability index (BI) and rock mass quality.