International Journal of Mining and Mineral Engineering (11 papers in press)
Optimization of opencast mining machinery noise using differential evolutionary algorithm
by Datrika Srinivas Rao, Debi Prasad Tripathy
Abstract: Noise levels produced by various mining equipments are high and exposure to such levels is considered as a severe problem. Many studies were carried out on machinery noise prediction using statistical and soft computing techniques, but less number of studies have been carried out to find global optimal value. The aim of this article is to develop and analyse the ability of a Differential Evolution (DE) algorithm to locate global optima of the far field noise levels produced by mining machineries in the mine. The objective function formulated is the maximization of sound power level (SPL) so as to determine the optimal distance, optimal directivity index, optimal sound power level (SWL) and other optimal attenuation parameters. The most essential challenge in optimization problems is CPU time. Performance and convergence speed of optimization algorithms have an essential impact on CPU time. Comparison with the best known variants of DE over the objective function reflects the superiority of the parameter tuning scheme in terms of accuracy, convergence speed and robustness. Results show that DE/RAND/2 is able to converge and find the optimum values faster compared to other mutation variants. Thus, DE algorithm with DE/RAND/2 variant seems to be a promising approach for machinery noise optimization problems.
Keywords: differential evolution algorithm; machinery noise; CPU time; sound pressure level; mutation variants; stochastic optimization.
Design of roof-contacted filling ratio and filling holes in the sublevel open stoping with subsequent filling method
by Hongjian Lu, Songlin Zhang
Abstract: The major influence factors to control the cost of filling mining method are the design about the roof-contacted filling ratio and the number of filling holes. Firstly, taking the typical mine with subsequent filling sublevel open stoping method as engineering background, the distribution law of backfill strength and the final flowing track of filling slurry in the stope were obtained by three dimensional laser scanner and laboratory mechanics tests. Based on which, the three dimensional numerical optimized model on roof-contacted filling ratio and the number of filling holes in subsequent filling sublevel open stoping method were established. Then, the distribution characteristics on maximum principal stress and the stable state of backfill with different roof-contacted filling ratios were revealed by calculating and analyzing of the model. The results indicate that backfill is in the stable state when it is more than 50%, and the safety of backfill is remarkably well especially when it is more than 75%. According to the stability of the typical mine rock mass, the lowest stope roof-contacted filling ratio is 65%. Finally, the number and location of filling holes in the stope were optimized according to the suggested roof-contacted filling ratio, the number of filling holes in typical mine are 6, and the recommendation scheme is roof-contacted ratio 70% (I).
Keywords: open stoping with subsequent filling method; roof-contacted filling ratio; filling holes design; final flowing track of filling slurry; backfill strength distribution law.
Improving the climatic conditions in development and production workings of hot underground mines by re-designing the auxiliary ventilation system - A case study
by Pedram Roghanchi, Karoly C. Kocsis
Abstract: The aim of this paper is to examine the current auxiliary ventilation system in a dead-end development at one of our partner mines in Nevada and investigate various auxiliary ventilation designs in order to control the heat load at the face and along the development heading. Different auxiliary ventilation setups were modeled and the climatic conditions were determined by means of simulation techniques to identify the optimum auxiliary ventilation arrangement which would be able to deliver the required air volumes and provide adequate climatic conditions for the mine workers at various levels of wok intensity (e.g. metabolic rates). For different work intensities, the maximum skin temperatures of a mine worker at the face and at the main return airway are compared versus the maximum allowable skin temperature. An airflow velocity of 1.5 m/s or higher is required to obtain an acceptable climatic condition with or without activity at the face.
Keywords: underground mining; auxiliary ventilation system; climatic condition; mean skin temperature; heat stress.
Non-Newtonian Thickened Tailings Slurry Flow through Open Channels
by Sadegh Javadi, Rahul Gupta, Paul Slatter, Sati Bhattacharya
Abstract: Flow of non-Newtonian thickened tailings suspensions is experimentally studied. The testwork was carried out with typical mining tailings and kaolin suspensions of varying concentration in the laminar, transitional and turbulent regimes. The experimental investigation used a 100-mm wide and 4.8-meter long rectangular channel which was geometrically and dynamically similar to a full-scale industrial channel. The flow regimes and solids particle deposition were extensively observed and reported. It is shown that, contrary to the previous findings, the critical Reynolds number, at which the flow conditions change from the laminar to transitional, can be as high as that for the Newtonian fluids (2000-3000). Nevertheless, the results still support the argument that with an increase in the apparent viscosity, the transitional flow emerges at lower Reynolds number. In addition, the current study experimental results along with previously published data-sets (Haldenwang-Slatter 2003 and Burger et al. 2014) are used to validate various open channel design models using combined Root-Sum-Square (RSS) values. In the laminar regime, Javadi et al. (2015) model gives a better prediction, while the turbulent regime is closely predicted by Wilson-Thomas model (1985, 2006) and Darby et al. (1992) models. Finally, it is verified that Haldenwang et al. (2010) model accurately determines the locus of laminar to transitional onset.
Keywords: non-Newtonian; thickened tailings; open channel.
Dump Slope Stabilization through Re-vegetation in Iron Ore Mines in Bonai Iron Ore Range A Review
by Vibhash Ranjan, Phalguni Sen, Dheeraj Kumar
Abstract: The process of mining has been long used for the excavation of mineral resources. The various kinds of waste released generally in an opencast iron ore mine during mining process include fine dumps; sub-grade Run-of-Mine (ROM) having low moisture content; low nutrient levels and pH; high metal concentration; etc. This paper provides an overview of the re-vegetation programme that can be used for slope protection and erosion control as vegetation is considered as a long-term solution for land reclamation. Re-vegetation helps in restoring the productivity of soil by reducing soil erosion and protecting soil from further degradation during land reclamation. There are several approaches to re-vegetation, such as coir matting, plantation of lemon grass, vetiver grass and local (host) plants, which may be used effectively to stabilize iron ore mines dumps. Of these methods, the plantation of local plants through the Miyawaki method has been found more effective than the conventional method of plantation. This method involves plantation of a number of local (host) plants, such as Karanj (Ponganna Pinnata), Shisham (Dalbergia Sissoo), Neem (Azadirachta India), Sal (Shorea Robusta), Kendu (Diospyros Melanoxylon), Amla (Phyllanthus Emblical) Jamun (Syzgium Cumini), Banyan (Ficus Benghalensis) and Krishnachura (Delonix Regia), closely spaced in a dump slope or small pit. The plants are selected on the basis of high survival rate and can reproduce or revive even under extreme environmental conditions.
Keywords: Re-vegetation; Lemon Grass; Coir Mat; Vetiver Grass; Local species; Selection of Plant species. Miyawaki Method.
Required strength estimation of a cemented backfill with the front wall exposed and back wall pressured
by Guangsheng Liu, Li Li, Xiaocong Yang, Lijie Guo
Abstract: Open stoping with delayed backfill is increasingly utilized in underground mines worldwide. A critical task in application of this type of mining method is to estimate the minimum required strength of exposed cemented backfill. Several analytical solutions have been proposed to evaluate the required strength of cemented backfill with one open face, confined by three rock walls. In practice, a cemented backfill in contact with an uncemented backfill on one side may need to be exposed on the opposite side. The uncemented backfill can apply a pressure on the exposed cemented backfill and affects its stability. In this study, a lateral pressure equal to the isostatic overburden pressure is considered for the uncemented backfill. An analytical solution is proposed for evaluating the minimum required strength of the cemented backfill with the front wall exposed and back wall pressured. The ensued solution constitutes an upper bound solution for assessing the minimum required strength of the cemented backfill exposed on one side and confined by an uncemented backfill on the opposite side. The proposed analytical solution is validated by numerical modeling performed with FLAC3D.
Keywords: Cemented backfill; Required strength; Critical strength; Analytical solution; Numerical modeling; Mitchell; FLAC3D.
Review on Low-Cost Wireless Communication Systems for Slope Stability Monitoring in Opencast Mines
by Guntha Karthik, Singam Jayanthu
Abstract: Slope stability is one of the primary problems faced by opencast mines. The conventional geotechnical sensors are monitored by technicians in the field and the available wireless monitoring systems like Slope Stability Radar (SSR), Light Detection And Ranging (LiDAR) are more expensive. The purpose of this paper is to introduce the different cost-effective real-time slope monitoring systems. Critical observations on recent low cost wireless slope monitoring systems were presented. By deploying the Wireless Data Transmission System using advanced antennas at respective slope instruments in underground or opencast mines, we can collect data without any physical connections. Wireless sensor networks (WSNs) are well suited to monitor the movement, and it consist of sensor nodes which measure physical quantities and transmit the preprocessed measurement results to a base station wirelessly. Developments in information and communications technology (ICT) support the collection, connection and analysis of data through sensing and monitoring of slopes in mines. This paper gives the detailed review on available low-cost wireless slope monitoring systems for opencast mines.
Keywords: Slope Stability; Opencast mine; Wireless sensor networks; Time Domain Reflectometry.
Draw Rate Management System Using Mathematical Programming in Extraction Sequence Optimization of Block Cave Mining
by Farshad Nezhadshahmohammad, Hamid Aghababaei, Yashar Pourrahimian
Abstract: Planning of caving operations poses complexities in different areas such as safety, ground control, and production scheduling. Draw control is fundamental to the success of block-cave operation. Although some complex theories and mathematical draw control systems have been applied in block-cave mines, most of them did not have an exact production rate curve to manage draw rates of drawpoints and are too complex to provide a solution for real block-caving mines. This paper presents a mixed-integer linear programming (MILP) model to optimize the extraction sequence of drawpoints over multiple time horizons of block cave mines with respect to the draw control systems. Four draw rate strategies are formulated to guarantee practical solutions. Furthermore, dilution and caving are improved indirectly, because the method considers the draw rate strategy. Application and comparison of the four models for production scheduling based on draw control systems are presented using 298 drawpoints over 15 periods.
Keywords: Block cave mine; Production rate curve; Draw rate; Mathematical formulation; MILP.
Oil Sands Production Scheduling and Waste Management with Optimum Cut-off Grade Policy
by Navid Seyed Hosseini, Eugene Ben-Awuah
Abstract: Cut-off grade is the criterion that separates ore from waste and it determines the amount of ore and waste material in the final pit limit. In order to generate an optimum production schedule for the mine life, cut-off grade optimization is used to determine the cut-off grade, duration of mining of the grade and the amount of material mined. This research developed a heuristic optimization model that generates an optimum cut-off grade policy and a schedule for ore and waste material including overburden, interburden and tailings coarse sand dyke materials for dyke construction in oil sands mining. Scenarios investigated include: no stockpiling and stockpiling with limited reclamation duration. The scenario of reclaiming the stockpile after one year had the highest net present value (NPV) as well as the highest cut-off grade profile. Reclaiming the stockpile after two years had less NPV due to reduction in processing recovery resulting from oxidation.
Keywords: Integrated Cut-Off Grade Optimization model; oil sands mining; production scheduling; waste management; dyke construction; stockpiling.
Assessment of Blast Induced Vibrations Based on Regulatory Criteria (A Case Study of Limestone Mine, Nigeria).
by Victor Abioye Akinbinu
Abstract: The aim of this study is to assess the effect of blast-induced vibration of limestone quarries on the environment. This was attained through extensive plan of measurements. Six blasts were carried out covering all the working faces with number of blast hole per blast ranging from 30 to 56. Weight of charge per delay ranged from 240 to 448 kg. The distance between the locations of the vibrograph and the center of the blast ranged from 0.8 to 3 km. The vibrograph was used to measure the maximum magnitudes of three mutually perpendicular components of the peak particle velocities and air blast over pressure levels. Complete wave traces of the vibrations were also recorded. Blast induced vibrations can cause human annoyance, discomfort, and damage to nearby structures. Hence, measurements of ground vibrations and air blast levels and use of published damage criteria are necessary to judge the design of the blasting operations, if it complies with the safe regulated levels. Ground vibration induced by blasting at the Quarries was monitored from selected locations. All of the events recorded during this research obey the USBMRI8485 and Office of Surface Mining (OSM) regulation criteria. Maximum allowed peak particle velocity does not exceed 0.75inch/sec (168.75 mm/sec) for the measured distances from blast point It was observed that the structures at the monitored locations were safe.
Keywords: air blast; blast-induced vibration; limestone quarries; peak particle velocities; published damage criteria.
Attracting young people to the mining industry Six recommendations
by Jan Johansson, Bo Johansson, Joel Lööw, Magnus Nygren, Lena Abrahamsson
Abstract: The present workforce in the mining industry is ageing and mining companies have difficulties recruiting young people who are not particularly interested in working in the industry. Simultaneously, mining companies tend to rely on contractors that offer volume flexibility and expertise, often in a combination that is economically appealing. This makes recruitment and development of the whole of the mining workforce complex. To recruit the right workforce, mining companies and their contractors need to cooperate and improve their knowledge about both attractive and repelling work features so that they can make wiser strategic decisions based on facts.
Based on a Swedish context, we discuss different aspects of attractive workplaces and summarise our lessons learned in six recommendations dealing with general health and safety issues, work organisation, competence development, gender equality, social responsibility, and outsourcing. We hope that these recommendations will provide some guidance on how future attractive mining workplaces can be achieved.
The paper is based on experiences from the Swedish mining industry and two large European Union projects, Innovative Technologies and Concepts for the Intelligent Deep Mine of the Future (I2mine) and Sustainable Intelligent Mining Systems (SIMS).
Keywords: mining; attractive workplace; automation; health; safety; risk; work environment; corporate social responsibility.