Reducing environmental hazards of blasting using electronic detonators in a large opencast coal project – a case study

Jul 2019 / by C.P. Singh, Hemant Agrawal, A.K. Mishra and P.K. Singh

The core objectives of Indian Ministry of Coal in its vision statement is securing the availability of coal to meet the demand of different sector of economy in an eco-friendly and sustainable manner. Coal India produced 567.37 million tonnes of raw coal in 2017-18 out of which contribution from opencast mines was 536.82 million tonnes (i.e. 95%). Deep hole blasting for high capacity excavators like draglines, 20 cum shovels becomes imperative for achieving high production targets. Thus, environmental hazards associated with deep hole blasting is also bound to happen. One of the serious problems faced by deep hole blasting is that of ground vibrations. In Khadia opencast coal project the power plants, Rihand dam is in vicinity and local population in and around mines, controlling ground vibration was of paramount importance for the project. Hence, it became a challenge for reduction of environmental hazards involving deep hole blast for dragline; shovels using electronic detonators, for providing precision delay and maximizing the vibration of explosive energy. The blast design parameters using electronic detonator for various blasts of dragline benches were tried to know the resultant profile of ground vibrations near human settlement of Khadia project. This has also resulted in improvement of powder factor (volume of rock fragmentation per kg of explosive used). This paper deals with, as to how the environmental impacts due to ground vibrations of rock blasting, are reduced resulting in no complaints for dwellers and any authorities in and around Khadia project.

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Prediction of blast-induced ground vibration by ANN, USBM and CMRI formulae for safety of the structures near surface coal mines

Jul 2019 / by Shankar Kumar and B.S. Choudhary

Ground vibrations, air blasts, fly rocks, back breaks, noises are the ill effects of blasting which are unavoidable but certainly can be minimized up to permissible level to avoid damages to the surrounding environment, structures. Among all the ill effects, ground vibration is a major concern to the engineers, designers, and environmentalists. Various laws have been communicated by scientists and are being adopted to keep in check the ground vibration levels. This study is conducted to predict the blast induced ground vibration (peak particle velocity) using ANN, USBM and CMRI formulae for the safety of the structures existing near surface coal mines. The data obtained from the different mines are analyzed and the correlation for different models are established to see their predictability.
Keywords: Blasting; peak particle velocity; ANN; maximum charge per delay; surface mine

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Drilling and blasting improvement in aggregate quarry at Thailand – a case study

Jul 2019 / by R.M. Bhatawdekar, Edy Tonnizam Mohamad, T.N. Singh and D.J. Armaghani

World class infrastructure around Bangkok is developed due to medium to large aggregate quarries situated up to 200 km from Bangkok utilizing granite, limestone and basalt as resource. Aggregate consumption will be exceeding 350 MTPA by 2019. Aggregate quarry under study has proposed increased production from 2.5 MTPA to 5 MTPA. Drilling and blasting accounts for 28% of total quarrying cost based on the study of various aggregate quarries in Thailand. Powder factor values (P.F.) is 0.40 – 0.66 kg/m3 at 80% passing over 0.5m. Considering drilling and blasting as major cost, existing practices of drilling and blasting are reviewed. Top hammer (TH) 102mm diameter drill is selected as compared to existing down the hole (DTH) 76mm diameter drill. For large quarries 6m × 7m is blasting pattern as optimized with 150mm diameter drill. Projected blast pattern is 4m × 4.75m. TH, DTH, rotary cutting and rotary crushing drills are evaluated. Some of the best practices at an aggregate quarry in Thailand for drilling include drilling accuracy, bench’s surface flattening by auto leveling. Blast performance is monitored for blast fragmentation, back break. Nonelectric detonators instead of electrical detonators and bulk emulsion instead of ANFO shall be utilized for future blasting operation.
Keywords: Top hammer (TH), down the hole (DTH), powder factor (PF), auto leveling (AL), bulk emulsion, non electric detonators (Nonel)

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Impact of miners’ QoL on productivity: a strategic study for optimizing coal mining operation through sustainable human resource management

Jul 2019 / by Archana Nath, Angad Kumar, Muniyan Sundararajan, Ritesh Kumar and Ajit K. Behura

This research article is an attempt made to study the impact of factors of the domains such as socio-economic, health, sanitation, living environment and working environment on quality of life (QoL) of miners of five coal mines industries. A questionnaire was prepared comprising 15 questions for each domain. Twenty miners per mine were assessed and the data was prepared using excel spread sheet. The quality of life indices were compacted using quality functions for each parameters based on the sensitivity function defined on the quality interval as per the standards or criteria intended. The results show that Ramkanali underground mine possesses the quality of life index of 32.86 while the production per capita was 121.854 and similarly Keshalpur underground mine, WMC opencast mine, BCCL Block-II opencast mine and Salampur underground mines possess 29.37, 33.54, 34.28 and 32.77 while the production per capita were 431.272, 467.561, 397.667 and 171.765 respectively. The present study reveals that the present approach for computing quality of life indices would be functional for planning socio-economic development activities. It is obvious that there will be significant correlation of quality of life index with the productivity; the study could not establish any relation between quality of life and productivity. Thus the study reveals that there may be other domain other than the fore said five, which has not been incorporated in the present study and such domains have to be identified so that the relationship may be established. The present approach is unique and very much useful for assessing not only quality of life but also any system individually. If the quality of the miners’ life with respect to socio-economic, health, sanitation, living environment and working environment is separately computed, this would be a very good study to prepare strategic plan for improving productivity for different mines.
Keywords: Miners’ quality of life, sustainable coal mining operation, human resource management in coal mines

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Analysis on evaluating the concentration of ventilated air methane in the coal mines using a thermodynamic approach

Jul 2019 / by Akash Talapatra

Ventilated air methane is usually released from the mine ventilation shafts in the coal mines. It contributes in a considerable extent on the increasing of the greenhouse gas emission in the atmosphere. The mitigating approach of this methane emission to the atmosphere is dependent on the controlling and monitoring the emission of this gas. That is why the concentration of the methane gas in the ventilated air and its oxidation mechanism to convert into another carbon molecule must be evaluated. In this study, there had been tried to propose an approach by which the thermodynamic oxidation mechanism is integrated with a hot power cycle to evaluate the required energy variation and efficiency variation according the variation of methane concentration and volume. This was the main purpose of this proposed study. Not only that, but also the mass and energy applied here are balanced and after that, it is easier to get a concept about the amount of cost to utilize the ventilated air methane per unit of methane.
Keywords: Ventilation air methane; thermodynamic efficiency; oxidation process, decarbonization process; compression ratio

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Increase of iron concentration and reduction of impurities in red mud from the Wenshan area of Yunnan Province by segregation roasting-low intensity magnetic separation

Jul 2019 / by Wei Ding, Yang Peng, Qiang Wu, Siyue Shen, Junhui Xiao, Guanjie Liang and Wenxiao Huang

Red mud is a solid waste produced during alumina extraction from bauxite. In this study, we pretreated red mud by segregation roasting to convert the iron from weak magnetic minerals to ferromagnetic minerals and then subjected the material to grinding and low intensity magnetic separation to obtain iron concentration. The effects of the chlorinating agent type, chlorinating agent dosage, reducing agent dosage, temperature, reaction time, additive, grinding fineness and magnetic field strength on the iron concentrate grade and recovery rate are studied. At a red mud/KCl/coke/ Na2SO4 mass ratio of 100:15:15:10, segregation roasting at 1100°C for 60 min, the roasted ore is ground to about 95 wt.% passing 0.045 mm and a magnetic field strength of 0.22 T, the final iron concentrate grade is 78.29% and the recovery is 84.08%, which is an efficient improvement of the valuable metal iron in red mud. The X-Ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy analysis of the iron concentrate shows that before the segregation roasting, the precious metal iron in the red mud is mainly in the form of Fe2O3. After the segregation roasting, the iron is transformed into a new iron mineral phase mainly composed of metal Fe and Fe3O4. The main impurities in the iron concentrate are calcium, silicon and aluminum.
Keywords: Red mud, separation roasting, magnetic separation, metallic iron

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Ergonomic intervention through ‘OCRA’: an ergonomic tool, for workposture assessment of periodic overhauling activities in mechanical industries

Jul 2019 / by Partha Mukhopadhyay and Netai Chandra Dey

Ergonomics is the science which deals with the perfect fit between man, machine and environment. This paper focuses on the Occupational Repetitive Action (OCRA) based working posture assessment of the industrial worker which is extremely important not only from ergonomic point of view but also to boost the comfort level of the worker. The method is based on the data for a set of joint motion including hand, arm, neck, back and the corresponding holding time in static and dynamic posture considering repetitive actions which has suggested as a preferred method to measure the risk of bio-mechanical overload of the upper limb in ISO and CEN bio-mechanical standard which provides criteria and assessment tools for risk evaluation at different levels in details. Hundred male subjects who are directly involved to the Periodic Overhauling (POH) in fabricating job are studied and assessed through the ergonomic tool OCRA. Based on statistical interpretation, the 33.33% of the subject are in low-medium risk, 50% are in the medium risk and the remaining are in the high risk. This result suggests an analytical risk assessment technique which is useful to design or redesigning the work station and strategy planning to increase the productivity maintaining worker’s physical and mental condition.
Keywords: Musculoskeletal disorder, bio-mechanical overload, OCRA, occupational health hazards, work posture assessment, work load

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