Fly Rock Research Articles

Protecting Mining Environments from Blasting through Impact Prediction Studies

A surface gold mine wishes to develop a new pit (Pit A) as part of its mining schedules. The proposed pit outline is about 300 m to the closest community. Blasting operations in Pit A would potentially create undesirable environmental impacts including fly rocks, ground vibrations and air blasts to neighbouring communities. Integration of proper planning tools or protocols for blasting at Pit A is the major concern of the Mine. Due to safety reasons, management wishes to explore the best blasting protocols that will restrain any blast impact to a 250 m buffer from the proposed pit outline. The Kuz-Ram fragmentation model was used to generate the optimal geometric parameters required for blasting at Pit A. Ground vibration, air blasts and fly rock impact prediction models were used to estimate the associated blast impacts to the neighbouring community. The predictions were made for blasting the oxides, transition and fresh rock formations to be encountered in Pit A. The predicted ground vibration and air blast levels were compared with the Ghanaian regulatory threshold of 2 mm/s. The predicted maximum fly rock distance (235 m) from the pit outline is within the established 250 m clearance buffer zone. The geometric drill and blast parameters and associated single-hole firing charges were used in the prediction models. The predicted results from this study will assist the surface gold mine to properly execute safe blasting operations with minimal impact to the neighbouring community. Due to known scattering of NONEL explosives in initiation systems, electronic initiation systems are recommended for blasting in the new pit.

A quantitative model for evaluation and classification of blastings in open-pit mines

By evaluation of the blasting results, a proper blast pattern can be presented. It is, therefore, essential to employ a reliable method to evaluate blastings for the effective control and optimization of the main cycle operations. This paper aims to propose a criterion for evaluating the blasting results such as the fragmentation, muckpile condition, back-break, and fly rock, and to make a possible comparison between the blast parameters including the blasting pattern, explosives used, hole depths, and volume of the blasted rocks in the lead and zinc mine in Angouran (Iran). Using the global criterion, making the decision matrix dimensionless, and defining the appropriate conditions for the results obtained, a scalar value is devoted for the blasts, whose larger values denote a larger deviation from the proper blasting conditions and express undesirable blasts regarding the blasting results. By taking into consideration the mining operation conditions and weights of the results obtained, the influence of the results obtained on the mining operation index is also investigated using the genetic algorithm. Furthermore, by composing the weighted decision matrix, the blastings are evaluated and classified. Analyzing the results obtained for blastings in the Angouran mine reveals that the proposed method is an effective approach for evaluation of the blasting results and comparison of the blasts.

Rock Quarrying and Sustainable Environment Management

Nearly 90% of Sri Lanka consists of Precambrian crystalline rocks except for a belt of Miocene sedimentary rocks along the north and North-west coast of the country. Gravel, sands and clays, particularly along river terraces, belonging to quaternary system are found resting on the Miocene formations and crystalline rocks. Precambrian crystalline rocks which most often occur as hills or mountains, consists of charnokites, migmatites and varieties of gneissic rocks. These rocks are suitable for road development and other constructions. Annual production of rock aggregates in the country is around 8 million cubic meters. During the recent times, due to large scale projects such as development of harbours, new air port and expressways, required large amount or aggregate material than usual. Colombo port city project alone will require about 3.5 million cubic meters of rock material within two years., There are over 2,500 Industrial Mining License (IML) grade quarries in Sri Lanka. The production vary between 1,500 m3 to 15,000 m3.per month. The operation of such a large number of rock quarries cause immense environmental damage. While development needs rock material, it is imperative to take remedial measures to mitigate the environmental damage caused by dust, noise, ground vibrations, fly rocks. Spraying of water at quarry and crusher plant sites, spraying of water into crushers and conveyor belts will reduce dust immensely. Quarry and crusher plant sites should be well protected by erecting temporary mesh to prevent spreading of dust and a permanent tree barriers should be created as early as possible. Noise, ground vibration and fly rocks should be controlled by designing proper blasting geometries and proper explosive usage. Ground vibration which causes severe damage to buildings and structures can also be reduced by excavating trenches between the blast and the relevant structure. Mined out area should be rehabilitated by refilling and planting useful trees or if it is a pit, it should be converted in to a pond, for breeding fish or providing water for agriculture or converted into a municipal garbage dump by sealing the bottom with a impermeable clay layer. Keywords: Rock quarrying, Ground vibration, Dust, Noise, Environment impacts mitigations

IMPACT OF QUARRYING AND CRUSHING ON SOIL QUALITY: A CASE STUDY IN TUMKUR DISTRICT, KARNATAKA

A study was carried out on the impact of quarrying and crushing waste on the quality of soil in Tumkur District. The quarries located in different parts of Tumkur District produces quarry wastes (aggregates), blasted materials (fly rocks), chemicals (explosives used for blasting) and dust (granite powder) generated from activity are spread and settled in the surrounding area. The soil samples were collected both near and away from the quarry and crushing sites. The collected samples were analyzed for various physico-chemical parameters viz temperature, pH, EC, organic carbon, nitrogen, potassium, phosphorus, zinc, copper, manganese, iron and boron using standard methods. The results revealed the deterioration of soil quality near the quarrying and crushing sites and this can be attributed due to the accumulation of dust. The soil properties are less affected away from the quarry sites.

A model for environmental quarry system based on particles, vibration and noise components

Environment is the surroundings in which an organization functions, including air, water, land, natural resources, flora, fauna, humans, and their interrelation. Surroundings in this context extend from within an organization to the global system. While the environmental impact refers to any change to the environment, whether adverse or beneficial, wholly or partially resulting from an organization's activities, products or services. Environmental Management System is the part of the overall management system that includes organizational structure, planning activities, responsibilities, practices, procedures, processes and resources for developing, implementing, achieving, reviewing and maintaining the environmental policy. The aim of this study is present model for environmental quarry components which are particles, Vibration and Noise (PVN) object. In addition, this study presented that noise emission sources in quarries and construction sites as being emitted from; mobile equipment, fixed processing plant and equipment, transportation (road and rail), blasting and construction and vibration main classified to Air Overpressure, ground vibration and fly rock and the last noise also dust emissions inventory for quarrying are Drilling, blasting, Handling of limestone, and Mineral processing had high significance dust emissions. To examine the model some sort of descriptive survey has been applied. According to a sort of a group’s random choosing skim, the survey sample population consisted of 285 randomly obtained from people who are living and work surrounding Langkawi Quarry (Malaysia). A significant part of the result discovered environmental quarry relate directly with research main factors such as particles, dust and vibration and its sub factors and the model be useful for environment quarry and practically environmental quarry system.

A Critical Comparison of Regression Models and Artificial Neural Networks to Predict Ground Vibrations

Blasting is important and an essential prerequisite in any opencast mine for fragmenting hard deposits. Blasting always produces unwanted effects like ground vibrations, noise and fly rock; among which ground vibrations effect is more on surrounding structures. Propagation of ground vibrations can lead to destruction of surrounding structures. Prediction of ground vibrations especially in terms of peak particle velocity is beneficial as opposed to conventional data monitoring techniques which can be expensive as well as time consuming. This paper uses predictors to estimate the intensity of ground vibrations and compares different methods of prediction methods like linear regression, multiple linear regression, non linear regression (NLR) and artificial neural networks. Intensity of ground vibrations generated from blasting operations was monitored in three different mines of limestone, dolomite and coal; obtaining about 168 ground vibration recordings in total. The statistical modelling or data-driven modeling has shown promise in the prediction of blast vibrations. Proposed a system of introducing site specific rock parameters like poison’s ratio, uniaxial compressive strength of rock and Young’s modulus to improve the correlation coefficient using statistical modelling (commonly called feature engineering in machine learning circles).

Improving Collar Zone Fragmentation by Top Air-Deck Blasting Technique

Air gap in an explosive column has long been applied in open-pit blasting as a way of reducing explosive charge, vibration, fly rock and improve fragment size. In conventional blasting a greater amount of explosive energy is lost in the generation of oversize fragments. Oversize fragments reduces loading and hauling efficiencies of equipment which requires secondary blasting. Recurring oscillation of shock waves in the air gap increases the time over which it acts on the adjacent rock mass by factor of 2–5. Top air deck blasting technique trial conducted with an application of gas bags at Chimiwungo pit resulted in an improved fragmentation of about 94 % less than 950 mm. Results obtained from the analysis of muckpile images using split-desktop exhibited that the mean fragment size was 264.81 mm and F20, F80 and top-size were 41.99, 683.18 and 1454.69 mm respectively. Optimum crusher feed size was as large as 1200 mm and crushed down to the 40 mm and only a small percent of the material was above 1200 mm. Gas bag application resulted in a significant reduction in explosives load in production holes without loss in fragmentation or movement of the collar zone. This reduced total cost of charging as compared to conventional blasts with a variance of $20, powder factor was dropped to an average of 0.86 kg/bcm. The technique reduced the cost of bulk blend explosive by 15 %, reduced overall cost of charging per hole by 12 %, enhanced premature ejections. The overall blast results were satisfactory, 443,624 tonnes of blasted material from the block which represented 90 % of the total muckpile material was within 900 mm size. The overall muckpile blasted was well fragmented.

EFFECT OF GEOLOGICAL STRUCTURE AND BLASTING PRACTICE IN FLY ROCK ACCIDENT AT JOHOR, MALAYSIA

Blasting operation is common method in hard rock excavation at civil engineering and mining sites. Rock blasting results in the fragmentation along with environmental hazards such as fly rock, ground vibration, air-blast, dust and fumes. Most of the common accidents associated with blasting are due to fly rock. A fly rock accident had occurred on 15 July 2015 at a construction site at Johor, Malaysia. Due to this accident, nearby factory worker was killed while two other workers were seriously injured after being hit by rock debris from an explosion at construction site, 200 m away from the factory. The main purpose of this study is to investigate the causes of fly rock accident based on geological structures and blasting practice such as blast design, pre inspection on geological structures, identifying danger zone due to blasting and communication and evacuation of personnel before blast. It can be concluded that fly rock could have been controlled in three stages; initial drilling of holes based on blast design, ensure limiting charge for holes having less burden or having geological discontinuity, and selecting proper sequence of initiation of holes.

Risk Assessment and Prediction of Flyrock Distance by Combined Multiple Regression Analysis and Monte Carlo Simulation of Quarry Blasting

Flyrock is considered as one of the main causes of human injury, fatalities, and structural damage among all undesirable environmental impacts of blasting. Therefore, it seems that the proper prediction/simulation of flyrock is essential, especially in order to determine blast safety area. If proper control measures are taken, then the flyrock distance can be controlled, and, in return, the risk of damage can be reduced or eliminated. The first objective of this study was to develop a predictive model for flyrock estimation based on multiple regression (MR) analyses, and after that, using the developed MR model, flyrock phenomenon was simulated by the Monte Carlo (MC) approach. In order to achieve objectives of this study, 62 blasting operations were investigated in Ulu Tiram quarry, Malaysia, and some controllable and uncontrollable factors were carefully recorded/calculated. The obtained results of MC modeling indicated that this approach is capable of simulating flyrock ranges with a good level of accuracy. The mean of simulated flyrock by MC was obtained as 236.3 m, while this value was achieved as 238.6 m for the measured one. Furthermore, a sensitivity analysis was also conducted to investigate the effects of model inputs on the output of the system. The analysis demonstrated that powder factor is the most influential parameter on fly rock among all model inputs. It is noticeable that the proposed MR and MC models should be utilized only in the studied area and the direct use of them in the other conditions is not recommended.

Development of an evaluation system for blasting patterns to provide efficient production

Blasting is one of the most important operations in mining projects involving production. Inappropriate blasting pattern may lead to unwanted events such as poor fragmentation, back break, fly rock, etc., as well as strong effects on the production rate. In fact, the selection of the most suitable pattern among the previously performed patterns can be considered as a Multi Attribute Decision Making problem. In this paper, first, from various performed patterns, the efficient and inefficient ones were determined using Data Envelopment Analysis. In the second step, linear assignment was used to evaluate the efficient patterns and recognize the most suitable pattern for providing high production rate. According to the obtained results, blasting pattern with the burden of 3.5 m, the spacing of 4.5 m, the stemming of 3.8 m and the hole length of 12.1 m was selected as the most appropriate blasting pattern and suggested for the future blasting operations.

Blast Vibration Analysis by Different Predictor Approaches-A Comparison

Blasting is a majormechanism of rock fragmentation. Explosive usage creates ground vibration, air over pressure as well as fly rock. Blast design is a process which needs to be monitored continuously as the rock mass exhibit many vibrations within the same boundary. Often the quantum of explosive had to be determined within safe vibration limit. Artificial Neural Network approach is also gaining wide recognition for its accuracy to match with the measured values. This paper evaluates the governing relations between PPV at varying explosive quantities and distances using established approaches as well as the results by application of artificial neural network.A total of nine blast events have been analyzed. Indian Standard and ANN approaches exhibit better correlation with the measured values of PPV as compared to that by other approaches.

Developing a mathematical assessment model for blasting patterns management: Sungun copper mine

Blasting is one of the most important operations in the mining projects that has effective role in the whole operation physically and economically. Unsuitable blasting pattern may lead to unwanted events such as poor fragmentation, back break and fly rock. Multi attribute decision making (MADM) can be useful method for selecting the most appropriate blasting pattern among previously performed patterns. In this work, initially, from various already performed patterns, efficient and inefficient patterns are determined using data envelopment analysis (DEA). In the second step, after weighting impressive attributes using experts’ opinion, elimination Et choice translating reality (ELECTRE) was used for ranking the efficient patterns and recognizing the most appropriate pattern in the Sungun Copper Mine, Iran. According to the obtained results, blasting pattern with the hole diameter of 15.24 cm, burden of 3 m, spacing of 4 m and stemming of 3.2 m has selected as the best pattern and has selected for future operation.

APPLICATION OF ARTIFICIAL NEURAL NETWORK FOR BLAST PERFORMANCE EVALUATION

Despite of technological advancement in the field of rock breakage, blasting is still an economical means of rock excavation for mining or civil engineering projects. Blasting has some environmental as well as societal side effects such as ground vibrations, air blasts, noises, back breaks, fly rocks, dusts and, of course, annoyance of inhabitants living surrounding the mining areas. Recent developments in the field of blasting techniques can minimize such ill effects by optimizing rock friendly explosive and blast design parameters. The purpose of this paper is to present the techniques, advances, problems and likely direction of future developments in exploring the applications of Artificial Neural Networks (ANN) in rock fragmentation by blasting and its significance in minimizing side effects to environment in particular and society at large. Many researchers have found the back-propagation algorithm in ANN is especially capable of solving predictive problems in rock blasting. ANN has been successfully applied in predicting, controlling, assessing impact of blast design parameters, ground vibrations, air blasts, back breaks etc. in mines. ANN needs to be applied in certain grey areas like predicting and controlling fly rock hazards in opencast mines, blast induced dust, blasting in jointed rockmass etc.

Unlocking Possibility of Blasting Near Residential Structure Using Electronic Detonators

Abstract: Ever since development of human civilization, mining and agriculture has been the backbone of growth. Today the most developed countries of the world are the ones focused on core economical development, be it power generation, steel making, oil and gas production, or agriculture. Mining has been gaining importance over the years both from the economic perspective and as an area of sustained research. With the advent of globalization, things have changed very fast and today it is an industry that is driving the economies of several nations. Global competition has propelled countries to reach higher production levels through better techniques of drilling and blasting, excavation and mineral processing. We now have bigger and faster drill machines and excavators. In Explosives technology too significant progress has been made towards having safer explosives and accurate initiating systems that have increased overall control over blasting in terms of vibration, fragmentation, throw, fly rock and overall blast economics. Explosives and Rock Blasting Technology has advanced so much in the last few decades that blasting can now be precisely performed, controlled and predicted. Development of new tools like electronic blasting systems and advanced simulation software has made it possible to customize blasting results as per requirement. These developments have helped mining engineer worldwide in reaping huge productivity benefits besides making it possible to meet the environmental norms even in most demanding conditions. Inability to blast large size shots on account of proximity of mines to human habitation have always constrained mine management in fully leveraging the strength of large size production equipments. Mine managers have been forced to conduct small blasts on increased frequency to provide feed to large capacity shovels while compromising on Shovel productivity on account of undesirable movement of shovels during blasting. This paper deals with a case study at SEB quarry of Tata Steel wherein it was difficult to fire a big blast due to existing nearby structures. A critical scientific study was conducted before successfully firing of one of the biggest shot of 83 tonnes in the history of quarry. The paper discusses the issues being faced, alternate solutions opted and the final outcome.

Investigating ground vibration to calculate the permissible charge weight for blasting operations of Gotvand-Olya dam underground structures / Badania drgań gruntu w celu określenia dopuszczalnego ciężaru ładunku wybuchowego przy pracach strzałowych w podziemnych elementach tamy w Gotvand-Olya

Abstract Ground vibration, air vibration, fly rock, undesirable displacement and fragmentation are some inevitable side effects of blasting operations that can cause serious damage to the surrounding environment. Peak Particle Velocity (PPV) is the main criterion in the assessment of the amount of damage caused by ground vibration. There are different standards for the determination of the safe level of the PPV. To calculate the permissible amount of the explosive to control the damage to the underground structures of Gotvand Olya dam, use was made of sixteen 3-component (totally 48) records generated from 4 blasts. These operations were recorded in 3 directions (radial, transverse and vertical) by four PG-2002 seismographs having GS-11D 3-component seismometers and the records were analyzed with the help of the DADISP software. To predict the PPV, use was made of the scaled distance and the Simulated Annealing (SA) hybrid methods. Using the scaled distance resulted in a relation for the prediction of the PPV; the precision of the relation was then increased to 0.94 with the help of the SA hybrid method. Relying on the high correlation of this relation and considering a minimum distance of 56.2 m to the center of the blast site and a permissible PPV of 178 mm/s (for a 2-day old concrete), the maximum charge weight per delay came out to be 212 Kg.

Flyrocks – Detection and Mitigation at Construction Site in Blasting Operation

Construction and mining industry spends heavy coins on blasting technology, explosives and their safe detona- tion, from India's perspective safe blasting holds even more important stand. In India, around 90% of production comes from surface mines. In any surface mine, blasting is a crucial operation. Explosives in large quantities has been used for fragmentation of rock in surface mines but only a part of the explosive energy has been used in doing the useful work, the rest has been consumed toward unwanted work such as ground vibration, fly rocks, noise and air blast. These blasting prac- tices provide quick, efficient and cheap over-burden removal compared to other processes. However, they are major sources of mine related injuries and accidents. Usually blasting related injuries are related to fly rocks, lack of blast area security, premature blast and misfire. Out of these, fly rocks and lack of security accounts for 68% of total injuries incurred by blasting practices. The blasting is required for fragmentation and displacement of the broken rock. Fragmented rock is not expected to travel beyond the limit of blast area or the desired throw. However, sometimes they do. These rocks travel- ling beyond blast area or the throw due to force of explosion is known as fly rock. As fly rock is a critical issue in mining and construction industry, hence it becomes more so important to learn the causes for generation of flyrock and the mitiga- tion measures. This paper deals with causes of fly rock, hazards associated with flyrock and precautions to be taken to con- trol them with the help of a case study at a construction site. The Flyrock accident can be averted by sticking to basic prin- ciples of primary as well as secondary blasting. The shock tube initiation system may be preferred over detonating cord. Further, supervision of blast hole charging should get high order preference and care.

Hard Kaolin High Yield and Stoping Technology in Suoli Mine

The backward blasting of the mine technology and stoping technology will lead to a long time of blasting, high labor intensity and low production efficiency, which also cause roof collapse and the blast of fly rock, support fall and overthrowing the chain-trigger, which cause a larger hidden of production. Through using the mechanical mining technology of the high yielding and efficiency of kaolin, which fundamentally improve the working conditions of workers and safety working condition, will laid the foundation for the increasing of production and efficiency. The production has been promoted from 250-300t/d to 550-650t/d now, which the efficiency is increasing more than 120%. Meanwhile, the optimal of blasting parameters is benefit to roof control after blasting, which can improve the efficiency of blasting, reduce the unit consumption of dynamite, which can save about 0.115kg/ m3; and reduce the intensity of the workers and the damage of the support. This construction technique can provides a reference significance for safe and efficient construction of the mine under similar geological conditions.

Prediction and Analysis of Blast Parameters Using Artificial Neural Network

In this study an attempt is made to predict the ratio of muck pile profile before and after the blast, fly rock and total explosive used, based on simple field tests as well blast design parameters. Prediction is done by making three different artificial neural network (ANN) models. Comparative statistical analysis is made among these three networks to ensure their performance suitability. Models of ANN were based on Feed Forward Back Propagation network with training functions – Resilient Backpropagation, One Step Secant and Powell-Beale Restarts. Total numbers of datasets chosen were 92 among which 17 were chosen for testing and validation and the rest were used for the training of networks. Statistical analysis is also made for these datasets. Considering performance for all the outputs, the best results are predicted by Powell-Beale Restarts, with an average percentage error of 5.871% for the ratio of muck pile before and after the blast, 5.335% for fly rocks and 5.775% for total explosive used. These parameters are predicted by number of holes to be blasted, hole diameter, pattern (spacing (m) X burden (m)), total volume of rock in a blast, average depth and total drill depth.

An assessment of environmental impacts of quarry-blasting operation: a case study in Istanbul, Turkey

This study evaluates the impacts resulting from quarry-blasting operation on nearby buildings and structures as it generates ground vibration, air blast, and fly rocks. In this paper, first blasting operation and its possible environmental effects are defined. Then the methods of blast-vibration prediction and commonly accepted criteria to prevent damage were introduced. A field experimental work was conducted to minimize the vibration effects at Saribayir quarry as it is an identical case for the many quarries situated in and around Istanbul, Turkey. Although the local surrounding geology and rock mechanics have great influence on vibrations as uncontrollable parameter, the charge weight per delay, delay period, geometric parameters of the blasts were changed to solve the existing vibration problem in the studied quarry. To obtain a realistic result, 10 blasts were carried out and 30 seismic records were made in different places mainly very close the buildings and the other vulnerable structures around the quarry. The evaluation is performed whether the vibration level are within safe limits or not. The prediction equation based on scaled distance concept is also determined, however, it is a site-specific model and need to be updated when the quarry advances. The safe blast parameters which minimize the environmental effect were determined for the Saribayir quarry.

An intelligent approach to prediction and control ground vibration in mines

Drilling and Blasting are still considered to be the most economical method for rock excavation either on surface or underground. The explosive energy, which breaks the rockmass, is not fully utilized for this purpose. Only 20–30% of explosive energy is utilized for fragmenting the rockmass and the rest wasted away in the form of ground vibration, air blast, noise, fly rock, back breaks, etc. Among them, ground vibration is considered to have the most damaging effect. A number of predictor equations have been proposed by various researchers to predict ground vibration prior to blasting. Still, it is difficult to recommend any one predictor for a particular ground condition because ground vibration is influenced by a number of parameters. These parameters are either controllable or non-controllable like blast geometry, explosive types, rock strength properties, joints patterns, etc. In the present paper, an attempt has been made to predict the ground vibration using an Artificial Neural Network incorporating large number of parameters, which affect the ground vibration. Results are also compared with the values obtained from regression analysis and observed field data sets. Finally, it is found that the neural network approach is more accurate and able to predict the value of blast vibration without increasing error with increasing number of inputs and non-linearity among these.