International Journal of Mining and Mineral Engineering (10 papers in press)
Investigating the effects of gemstone mining on the environs: a case study of Komu in Southwestern Nigeria
by Moshood Onifade, Adeyemi Aladejare, Bayo Adewumi
Abstract: Mining engineering practice involves the extraction of minerals from the earth with significant effect to the environment. Though this operation is important to living better lives but causes more damage to the landscape than ever before. This research examines the effects of gemstone mining by investigating soil and water samples collected from different locations of a mining community in Nigeria taking into consideration the concentration of heavy metals and micro nutrients, physiochemical parameters and cation exchange capacity present in these samples. These concentrations were compared with the World Health Organization (WHO) standards. The concentrations of heavy metals, micro nutrients and physiochemical parameters obtained from the sample locations varies from one location to another. The results for heavy metals concentration obtained from the soil samples are 0.30, 0.90, 0.09, 0.995 and 39.40 mg/kg for lead (Pb), copper (Cu), cadmium (Cd), zinc (Zn) and iron (Fe) respectively. The values of micro nutrients concentration in the soil are 4.90, 5.295 and 0.97 mg/kg for sodium (Na), magnesium (Mg) and aluminium (Al) respectively with sequence, Mg > Na > Al. The results of physiochemical parameters obtained from the water samples are 7.495 mg/L, 187.00 mg/L, 233.414 mg/L, 70.00 mg/L, 16.52 mg/L, 6.28 mg/L, 14.65 mg/L and 10.25 mg/L respectively for pH, hardness, chloride, alkalinity, total solids, total dissolved solids, total suspended solids, sodium and potassium. When the results of soil and water analysis were compared with WHO standards, it was found that the values obtained were lesser than the WHO acceptable limit for certain heavy metals. However, the concentrations of Cd and Fe in the soil samples are higher than the WHO permissible limit in soil which implies that the soil is toxic and not good for agriculture purposes.
Keywords: Gemstone mining; environment; pollution; WHO standards; soil analysis; water analysis.
Evaluation of the vibration accelerations of drill bit for the well rotative-vibration drilling using the cavitation hydrovibrator
by Olexiy Nikolayev, Yuriy Zhulay, Yuri Kvasha, Nikolai Dzoz
Abstract: Cavitation hydrovibrator is one of the promising devices to intensify drilling of geological prospecting and production wells. Cavitation hydrovibrator transforms the stationary flow of drilling mud into a discrete-pulsed flow of increased power. The mud oscillating flow in hydrovibrator is converted into high-frequency (1 000 Hz 20 000 Hz) vibrations of the drill bit. A method for determining the longitudinal vibrations of a drill string with bit has been developed. The method is based on the results of experimental studies of the dynamic interaction between longitudinal oscillations of the drilling string with rock massive by mathematical modeling this process with use finite-element discretization of drilling string. An obtained satisfactory convergence of the computed vibration accelerations of the drill bit and experimental data confirms the adequacy of the developed mathematical model and the ability with its help to determine the rational operational modes of the hydrovibrator.
Keywords: rotative-vibration well drilling; high-frequency downhole cavitation hydrovibrator; drill bit; longitudinal acceleration;.
Investigation of DPM dispersion in unventilated dead-ends using transient flow modelling
by Ramakrishna Morla, Shivakumar Karekal, Ajit Godbole
Abstract: This paper presents a detailed study of DPM dispersion in unventilated dead-end cross-cuts in an underground mine. The dispersion and dilution of DPM was measured in dead-end with time when the air is flowing in the main gallery. Parametric studies were conducted by varying the dead-end cross-cut lengths (10 m,15 m, 20 m and 25 m), varying cross-cut angles (450, 900 and 1350) with the main gallery and varying the velocities (0.5 m/s,1m/s ,2 m/s, 3 m/s, 4 m/s) in the main gallery across the cross-cuts. The results obtained show that longer time durations are required to dilute DPM for greater dead-end cross-cut lengths and angles. For 50 m dead-end cross-cut, it took five hours to reduce DPM concentration from 820
Keywords: Dead-end; cross-cut; DPM; CFD; Unventilated areas; Transient Flow.
Enhancing productivity through effective spoil stability management in an open cast coal mine
by Nompumelelo Mpembe, Bekir Genc
Abstract: The paper investigated the best practical dig spoil sequence which addressed circular failure in waste spoil piles and enhanced productivity through an improved coal exposure rate. This involved the evaluation of two overhand - chop and three dozer pushover dig spoil sequences through DragSim software and an MS Excel dragline calculator. The software provided spoil profiles for geotechnical analysis and the calculator generated productivity indicators (digging rate, coal exposure rate and rehandle percentage). The sequences were ranked in terms of the ability to meet the mine budget requirements and best practice standards for stability and productivity.
The best practical dig spoil sequence was the oblique spoil side dozer pushover sequence. It was recommended that Pit B be split in two halves: a modified overhand - chop and oblique spoil - side dozer pushover sequence for the first and second half, respectively.
Keywords: Opencast coal mining; stability management; DragSim software; dig spoil sequence; circular failure; waste spoil pile and competent weathered sandstone.
Mine health and safety: Influence of psychosocial factors on musculoskeletal disorders among miners in Pakistan
by Izhar Mithal Jiskani
Abstract: Mine health and safety is considered to be one of the fundamental determinants of sustainable mining. The purpose of this study was to analyze the severity of musculoskeletal disorders (MSDs) and to investigate the influence of psychosocial factors on its development. The data from 252 coal miners was collected through a self-administered questionnaire. Ordinal logistic regression modeling was performed to examine the association between MSDs and psychosocial factors. The results show that miners face moderate to severe risks of MSDs. The elbow, lower back, and knee were the most commonly reported complaints. Job demands and control at work were the psychosocial factors that increase the risk of developing MSDs. Whereas, low monotony at work and commitment to the organization reduce the chance of developing MSDs. The findings of this study will be a significant endeavor to formulate preventive management programs to promote miners health and safety.
Keywords: mine health and safety; musculoskeletal disorders; psychosocial factors; sustainable mining.
Numerical Simulation on the Broken of Coal and Rock with Different Fillers
by Fei Liu, Yuesong Tang
Abstract: By setting different stemming in the coal and rock at the bottom of the borehole, the effects on the propagation of blasting stress waves were studied. The ANSYS-LS/DYNA with damage model was used to simulate the propagation of blasting cracks in the coal and rock. The results show that the speed of propagation is significantly accelerated when the stress wave entering the interior of the rock mass. Different stemming has few effects on the crushing of coal. When water is used as filler, the obstruction on the stress wave is slightly greater than that of the coal body itself. When the soil is used as filler, it has the greatest hindrance to stress waves and the smallest fragmentation of rock mass.
Keywords: stress wave; coal and rock; tensile damage; numerical calculation analysis.
Factors to be considered in establishing a scanning laboratory for testing the accuracy of terrestrial laser scanning (TLS) technologies.
by Peter Kolapo, Frederick Cawood
Abstract: Laser scanning is a 21st century mapping technique used to generate high density point cloud data in three dimensions (3D). The 3D scans can be used for surveying, mapping and monitoring of rock mass movement in mining. For high precision and reliable work, the instrument must be used correctly and regularly calibrated and checked to ensure that it constantly performs according to manufacturers specifications. In this study, a Leica Total Station TCR 1201+ and a Trimble S6 Total Station were used to establish accurate coordinates for a control beacon and scanning targets. Thereafter, the scanning of the targets was carried out using a FARO Focus XD 130 terrestrial laser scanner. A comparison was conducted using the coordinates from the terrestrial laser scanner and Total Station to examine the point accuracy of the FARO scanner. The result from the comparison between the laser scanners coordinates and the total station coordinates showed that the FARO Focus is capable of producing accurate point cloud data that can be used for the purpose of monitoring underground rock mass movements. Lessons learnt during the development of the short-range scanning laboratory are summarised as factors to be considered when attempting to recreate such laboratory for testing the accuracy of laser scanners. These factors include operator skill and workflow, robust target designs, scanning geometry, full target visibility during scanning, calibration of instruments before task, laser scanner field of view and application of systematic and atmospheric conditions during measurements.
Keywords: Terrestrial laser scanning technologies; Accuracy Testing; short-range laser scanning laboratory; rock mass movement.
Stress Analysis of the Stope under the Influence of Horizontal Tectonic Stress
by Zhang Fengda
Abstract: The horizontal tectonic stress is one of the important reasons for water inrush, which is mostly caused by the geological structure. The stress distribution around the stope is analyzed by revised mechanical model. The distinctions in the maximum principal stress between revised formula and the original formula are analyzed. Numerical models are established with different horizontal tectonic stress intensity in far field. When the horizontal tectonic stress is smaller than the vertical stress in far field, comparing to original maximum principal stress, the maximum principle stress of roof and floor in front of stope is larger, and the maximum principle stress of the roof and floor in the gob is smaller. This leads to the increase of shear stress near the stope, and the shear plastic damage of rock mass is more prone to occur. The result of theoretical model is validated by numerical simulation.
Keywords: westergaard stress function; fracture mechanics; horizontal tectonic stress; mining engineering; numerical simulation.
THE INFLUENCE OF HYDRAULIC BACKHOES TECHNOLOGICAL PARAMETERS ON THEIR CAPACITY AT OVERBURDEN OPERATIONS
by Oleg Litvin, Magerram Gasanov, Sergey Zhironkin, Maxim Tyulenev
Abstract: Modernization of the world coal industry suggests massive replacement of old rope shovels by new hydraulic backhoes. These excavators can be effectively used in complicated geological conditions but their technical capacity sufficiently depends on the technological parameters and schemes. A mathematical model of calculating of backhoes capacity considering features of their application for blasted rock ex-cavation is given in the article.
Keywords: Open-pit mining; backhoes; technical capacity; technological parameters.
Experimental study on the strength of soil-cement with additions of mineral powder and ferronickel slag powder
by Feng Chen, Shenghao Tong
Abstract: With the rapid development of soil-cement application technology, soil-cement is widely applied in mine development, such as mine road construction, pit repair, stope reinforcement and mine backfill, etc. In this paper, ferronickel slag powder and mineral powder are applied in soil-cement to study the impact of their content on the strength performance of soil-cement, so as to draw on local resources, recycle solid wastes and reduce the amount of cement on the basis of ensuring the strength performance of soil-cement. The test shows the optimal content of ferronickel slag powder is 20% among additions of only ferronickel slag powder at levels of 0%, 10%, 20%, 30% and 40%. Further investigation indicates that the optimal results can be reached by adding different content of mineral powder. The results show that the addition of ferronickel slag powder has a greater impact on the strength of soil-cement at the early age. However, with the increase of age, the strength decrease rate of soil-cement with ferronickel slag powder reduces. When ferronickel slag powder and granulated blast furnace slag are mixed, the performance of soil-cement at the early age is better than that with ferronickel slag powder alone. The optimal combination is that ferronickel slag powder accounts for 20%, among which the mineral powder replaces 30% of the ferronickel slag powder mass.
Keywords: muddy soil; soil-cement; ferronickel slag powder; mineral powder; compressive strength.