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The article presents an outline of methods and certain results of laboratory tests, underground tests and model tests, aimed at assessing performance of a powered shield support on the floor of low strength parameters. The tests were conducted within the framework of GEOSOFT project co financed by Research Fund for Coal and Steel (RFCR-CT-2010-00001). The described research works were conducted by Central Mining Institute (Glówny Instytut Górnictwa), Janina coal mine and Becker-Warkop

Aug 1, 2013

By Stanislaw Trenczek

Natural hazards such as rock bumps, methane, coal dust explosions, airborne respirable dust, outbursts of gas and rocks, water, radiation caused by natural radioactive materials, spontaneous fires, and climatic hazards, occurring in the Polish hard coal mines, should be controlled. These hazards are characterized by different scale levels numbered from 2?5. To recognize the amount and levels of hazards, research works were carried out in 109 mining districts of mines belonging to Jastrzebska Spólka Weglowa, Katowicki Holding Weglowy and Kompania Weglowa. These are 86 % of all mines and could be regarded as representative of the majority of Polish mining. The hazards have been classified as regards the frequency of their occurrence as: commonly occurring ? with a frequency of 100 % (like airborne respirable dust and fire hazards), high occurrence frequency ? frequency from 60 to below 100 % (methane hazard ? 83.5 %, coal dust explosion hazard ? 92.0 %, and water hazard ? 99.1 %), medium occurrence frequency ? from 30 to below 60 % (rock-bump hazard ? 52.3 % and climatic hazards ? 51.4 %), and episodic occurrence frequency ? below 30 % (outburst of gas and rocks and radioactive hazards). The dynamics of effects of growth in hazard levels to their intolerable values is diverse. Some of them are passive in nature, which allows for longer observation of changes and appropriate early response (as for climatic and spontaneous fire hazards). However the majority of them take on the character of disasters, like methane or coal dust explosions and damage of the excavation structure ? as occurs after a rock-bump or rock outburst; and creation of an atmosphere unfit for breathing ? during open or spontaneous fires, or after gas outbursts containing methane. There are also latent hazards whose effects do not influence indeed a process of production; however they are detrimental to health when a worker is exposed for a long time to airborne respirable dust and radiation. For other types of hazards a level of danger may be only estimated. Since the systems monitoring allows a wider range of control, therefore, aside from rock-bump and methane hazards, there are monitored also fire hazards including measurements of other air parameters (velocity, pressure, humidity, temperature, O2, CO2 concentration). A few types of monitoring systems are used in Polish mines, like the monitoring systems for environmental parameters such as SMP-NT, SMP-NT/A, the telemetric systems CST-40, CST/A, including the computer-aided system for methanometry control officer SWµP, the computer-aided measuring systems KSP-1, KSP-2, KSP-2C, or the production and safety control system VENTURON. The underground part of the systems monitoring of natural hazards contains measuring devices and equipment for automatic control (power-off) of machines and electric devices in case of increased methane hazard. The surface part of the monitoring system allows the measuring data to be visualized and pre-alarm (warning) and alarm states to be displayed. Furthermore it makes it possible to archive and report the data and to control the underground supply and signalling devices. The EMAG Institute developed monitoring methods to extend a measuring range of monitored parameters (such as methane and fire hazards) as well as to monitor so far unmonitored hazards like dust hazards (by continuous monitoring of dust levels in mine air) and climatic hazards (by online monitoring climatic parameters of mine air).

Aug 1, 2013

By P. Plante

Contaminated neutral drainage (CND) is characterized by the presence of metal concentrations above regulatory requirements at circumneutral pH in mine drainage. The generation of CND by tailings and waste rocks is a growing concern for the mining industry due to increasingly restrictive regulatory requirements. Difficulties in CND prediction arise from the low oxidation rates of sulfide minerals and from the metal retention potential within the wastes. In fact, sorption phenomena may induce an important delay in the development of CND. For now, it is not possible to adequately consider this delay using the prediction tools developed for acid-mine drainage, such as humidity cells, columns and lysimeters. This work aims to present the new approaches currently under study for CND prediction, particularly the use of a chelating agent in kinetic tests. The main challenge of CND prediction is to quantify the metal retention potential of mine wastes, especially when sorption phenomena are involved in metal retention. Three approaches are currently used to overcome this difficulty. Firstly, the sorption potential is estimated using batch sorption studies. The second approach consists of artificially saturating the sorption potential of the mine waste by contact with a contaminated leachate in sorption-enabling conditions until saturation of the retention potential. These approaches both require that the possible metals involved in CND are known (as well as their chemical speciation) prior to the tests, which require an exhaustive material characterization. Although the two methods enable a qualitative estimation of the retention potential of mine wastes, their results are difficult to scale up from the laboratory to the field since some important parameters are not taken into account. A third proposed approach consists of inhibiting metal sorption at the source using chelating agents. The hypothesis is that chelating the metals immediately upon their release from the oxidation of sulfide minerals will inhibit all geochemical interactions (sorption, complexation, secondary mineral precipitation, ion exchange, etc.) between the metal and its environment. The ideal chelating agent will inhibit geochemical interactions after metal release in the drainage waters without having any impact on the sulfide oxidation and acid neutralisation rates. These approaches were tested over a waste rock sample that is known to naturally generate CND after a few decades of weathering. Results show that kinetic testing (weathering cell, ± 70 g samples) using a chelating agent (EDTA) in the leaching water renders higher metal concentrations in the leachates than a control sample without EDTA, suggesting that sorption (and possibly other geochemical interactions) is inhibited. These results suggest that the combination of these approaches can be efficiently used for more precise CND prediction from mine wastes. Future work will be done using the chelating agent approach over larger scale tests such as columns (± 80 kg samples) and field cells (± 100 tons) in order to propose an integrated approach for CND prediction.

Aug 1, 2013

By M. Carvalho

The primary motivation underlying the proposal of polygeneration systems for mine sites is to increase the efficient use of natural resources by combining different technologies and energy resources while satisfying energy service demands. For many mineral producers, particularly in Canada?s mining extremes of climate and depth, energy in support of mineral production can be the second largest cost centre after labour. A generic methodology is proposed for the design of energy supply systems in mine sites, based on a search for the minimum discounted cost of energy supplied for all feasible different plant configurations. These configurations can be represented within a connectivity matrix which corresponds to a network representation. A Mixed Integer Programming formulation is set out for the multiperiod synthesis and operational planning problem. This is characterized by i) binary variables for the selection of technologies, ii) integer variables for the determination of the number of units installed, and iii) by continuous variables for the representation of energy and economic flows. Through the integration of particular energy supply strategies matching specific mine circumstances (on-grid, remote, degree days, etc) and consideration of technologies that improve energy efficiency, hitherto not considered new technologies and demand management systems or new perspectives on optimal mine site energy supply can be investigated. Some of these investigations identify the economic conditions through which biomass energy feedstocks should be used, for direct heat production, for gasification and providing for Fischer-Tropsch syndiesel manufacture. As well as integrating demand from mobile diesel-fuelled plant into an optimization procedure that hitherto has only been considered for static energy production and consumption plant, this analysis shows how the techniques can be used to explore economic conditions of threshold prices for biomass (purpose-grown biomass and peat are considered herein) and trucked-in diesel. The methodology also allows for electricity and syngas storage and diesel and biomass bunkering. Within the paper the energy demands for a remote, open pit mining operation located in Northern Ontario are considered as a case study to illustrate the technique and investigations. As expected, for mines close to electricity, natural gas, and diesel distribution infrastructures, the optimal choice is to connect. When a constraint is applied specifying that connection is not possible, as would be for the case exemplified, the optimal choice includes some of the more exotic options for mine site energy supply.

Aug 1, 2013

By M. Moghadami

Design and construction of underground openings are associated with many uncertainties with regard to input data. In the construction process of underground openings various levels of risks exist and these affect the safety and profitability of the project. The development of underground openings can be broadly categorized into three major phases of data collection, design, and construction. A significant level of uncertainty is associated with some of the key parameters involved in the aforementioned development phases. Moreover, it is very difficult to evaluate and quantify the effects of uncertainties on the underground project construction process. Additionally, the interactions between important risk elements are typically not well understood. The intention of this study is to develop a general risk model for underground opening projects located in soils and weak rock masses. The goal of the research is to identify and quantify important geotechnical risk elements. Moreover, a weighting procedure will be proposed for the identified risk elements. Finally, all important risk elements will be assembled into a general model with emphasis on geotechnical parameters. The final objective of this study is to apply the proposed model to a real underground project scenario and verify it for actual field conditions. The proposed model, once calibrated properly, will provide a useful support tool for the decision making process.

Aug 1, 2013

Drilling is a common process in mining and petroleum engineering applications which have different objectives. For example, drilling deep boreholes in tight gas formations and gas shales is becoming more popular in the oil and gas industry. By contrast, drilling deep small sized holes for mineral exploration in hard rocks is performed to obtain samples for grade analysis purposes. In both applications optimising the drilling process includes using the most effective operating parameters such as rotation speed and weight-on-bit in order to maximise the rate of penetration. Obtaining the optimum drilling parameters requires sensitivity analysis over a range of data, which would be costly and time consuming during real field operations. Therefore, conducting several experimental simulations in the lab would be very beneficial before field operations begin. A drilling rig was designed and developed to simulate various drilling scenarios. The rig works in conjunction with an existing true triaxial stress cell (TTSC) which is in use for different petroleum related applications. The rig allows drilling into a cubic rock sample of up to 300 mm size. Three independent stresses can be applied to the sample to simulate real in-situ field stress conditions while the sample may be saturated with fluid. A significant feature of the rig is its ultra-high speed rotation which can rotate up to 8000 rpm: this is to simulate hard rock drilling for mineral exploration applications where large weight-onbit could damage the bit cutters. With the proposed design, a drilling fluid of any type can be circulated in the simulated borehole similar to the real situation, to study its effect on drilling performance. The TTSC drilling lid is equipped with torque and drag measurement systems which are two important drilling parameters to be recorded during drilling operation. It is believed that this new drilling rig will open opportunities for performing major new applied research in the area of more efficient drilling in both oil and gas bearing formations and mineral exploration applications.

Aug 1, 2013

By D. J. Xue

Four kinds of coal-rock combination were subjected to three kinds of stress waves in the SHPB numerical simulation. The wave propagation and the changes of the strain energy in the coal-rock combination during the dynamic impact process were recorded as well as the contact force. The dynamic response law of coal-rock combination was obtained. It was found that the coal had better reflectivity than the rock because of coal with larger impedance. In contrast the rock had better transmissivity. As the crest value of the incident wave increased, the increment in the crest value of the transmitted wave weakened in the coal-coal group, coal-rock group and rock-coal group, in contrast, the increment in the rock-rock group increased.

Aug 1, 2013

By D. L. Millar

The hydraulic air compressor (HAC) is driven only by water, held up by a dam, to create relatively low head (typically 10-20 metres), such that the developed hydropower is used to cause flow in openings deeper underground. Air is entrained in the water at the inlet to the sub-surface openings (an air to water volume ratio of 1:1 is reported to be optimal) and is compressed as it is carried along by the deepening water flow. At depth, and with lower water velocities arising from larger cross sectional area tunnels, air bubbles separate out of the water flow and are collected in a receiver space above the flowing water. Water, free of air, then passes back up a return shaft (up-pipe) and rejoins the river or stream flow. In principle, an HAC can produce any pressure and flow rate required, given large enough shafts and enough water supply with head sufficient to overcome frictional resistance in the sub-surface tunnels. Practically, as air solubility in water increases with pressure, HAC installations with depths greater than 100 metres may lead to higher rates of compressed air loss, without special separation measures. A modern HAC application for mine refrigeration and cooling is presented.

Aug 1, 2013

By Kenichi Fujino

Severe disasters have struck Japan in recent years. Following these disasters, construction robots have played important roles in investigation and restoration work in the disaster regions. To be applied in this way, construction robots require many functions according to the purpose of their use in each case. There are clear differences in the functions and usage conditions required by investigation robots and those required by execution robots. These differences will be important when designing and operating construction robots in the future. This report introduces a volcano exploration robot and unmanned execution system as examples of construction robots used for investigations and executions respectively. Based on this, the report organizes important characteristics of construction robots and explains differences in the concepts of disaster investigation robots and disaster restoration robots. Because they are used in harsh natural conditions and do not have any execution functions, efforts are made to clarify the fact that investigation robots have to overcome many problems such as mobility. When a construction robot is used, the scenario of the operation of the construction robot (execution plan) is extremely important, and in addition, it is necessary to clearly define the way it will be used according to the purpose of its use and specification conditions. In a plan for an unmanned execution system, it is possible to mitigate several strict prerequisite conditions by proposing a well-constructed execution plan. For example, the execution efficiency of an unmanned execution system can be improved by effectively using a temporary road.

Aug 1, 2013

By Tao Cheng

Previous research and applications in construction resource optimization have focused on tracking the location of material and equipment. There is a lack of studies on automated monitoring of the interaction between workers and equipment for safety purposes. This paper presents a new approach for measuring the safety performance of construction personnel particularly when they work in very close proximity to moving equipment as well as static hazards such as chemical and flammable substances. A method of generating hazardous zones according to the geometric and kinematic characteristics of the considered hazard is introduced. The spatio-temporal relationships between the hazardous zones and workers? positioning data collected by real-time location sensing technology are automatically analyzed. This approach has been validated in a controlled test bed environment that simulates a construction site. Results indicate that worker?s safety performance of selected activities can be automatically and reliably measured using the developed approach. Furthermore, a heat map is generated for visualizing proximity related issues in the test bed using the computed results.

Aug 1, 2013

By P. Blonde

Recent analysis has suggested that a balanced recovery profile can improve flotation bank performance. Test work was conducted to test the balanced profile concept at the Penhorwood talc mine near Timmins, Ontario, Canada. Plant trials were devised to determine how to control the recovery profile and the resultant impact on grade and recovery in a rougher bank of four cells. Accompanying gas dispersion measurements revealed a maintenance issue with one cell that was corrected. By manipulating air and frother addition it was possible to bring the bank closer to a balanced recovery profile and the down-the-bank grade/recovery improved. Plant production showed an increased talc grade at similar yield with the balanced profile. The results provide justification for a long term plant trial.

Aug 1, 2013

By T. Winkler

This paper presents elements of the Virtual Working Environment for identification of hazards occurring in the mining industry. The Virtual Working Environment includes models of machinery and models of anthropometric features. Examples are given for identification of technical hazards at the design stage using the following computer programs: Finite Elements Method, Multibody System Analysis and Human Body Modeling. One of the methods to improve work safety at the machine and equipment maintenance stage is to share design and operational knowledge in a form of an Interactive Electronic Technical Manual (IETM). An IETM is created using so-called reusable knowledge elements connected by relationships. A metamodel created in Unified Modeling Language is one of the forms for description of these relationships. The metamodel can represent, for example, interrelations between elements of repair procedures. Examples of procedures realized during the replacement of a damaged cutting bit are presented and discussed.

Aug 1, 2013

By Kan Xing

This paper introduces common detrimental consequences to the environment from mining in the Beijing West Mining Area. For example, ongoing mining operations can cause the following environmental deterioration: rock burst, roof rises, roof falls and inrush (Pit dash for ward water). Post-closure, after minerals resources are exhausted, the following environmental issues may remain: landslides (collapse, and mud-rock flow), dropping or exhausted water tables, water pollution, desertification and soil erosion, water accumulation, Slay endanger, ground subsidence, and causal factors in seismic activity. This paper analyzes this wide range of environmental consequences of mining, and offers a theoretical foundation to underpin a corresponding management scheme.

Aug 1, 2013

By Jinsuo Zhang

Investment in coal resource development is affected by a variety of uncertain factors. Investors can make a flexible, strategic decision to achieve the value of risk implicated in those uncertain factors. Therefore, based on real-option theory, we identified key uncertain factors that affect a coal resource investment project, and revealed the formation mechanism of option value in coal resource developing investment project. Then, a multi-factor decision making model was established for a coal resource development investment project with random changes of coal price, interest rate, convenience yield and production cost. Finally, we tested the model and analyzed relevant parameters by applying living data. Our results indicate this model reflects the value of risk implicated in uncertain factors for coal resource development investment, and is able to determine a critical point of decision making change when coal price and production cost varym respectively. By means of parameters analysis, the convenience yield has a positive effect on the project value. The interest rate has a negative effect.

Aug 1, 2013

By J. Dubinski

Underground mining of copper ore in the Legnicko-Glogowski Copper District basin generates a number of seismic events, whose energy often exceeds 108 J (Butra, 2010). The number of tremors and their location shows that the area of rock mass involved in the deformation and failure processes significantly exceeds the area of mining operations. Locations of seismic foci of high energy tremors, as well as the aftershocks that accompany them, extend hundreds of metres, confirming that processes to restore the energy balance of rock mass occur in a short amount of time and over a wide area. Thus, an area of similar size should be considered in predictive analyses of the tremor?s position. It should be emphasized that a large portion of the rock mass still has a level of freedom resulting from the way the rock mass is held together and its geometric continuity. This level of freedom is dependent on the scale and duration of mining, the number and size of natural structures, and rock mass pressure, including gravitational pressure constricting individual fragments of rock mass in the area (Burtan, 2012). It can therefore be assumed that in real conditions, areas where mechanical strength of the layers has been exceeded may be located a considerable distance from each other and do not necessarily need to coincide with the working area location. In this sense, a rock mass influenced by mining exploitation is essentially a rock mass in which numerous fragments with concentrated energy exist simultaneously. Energy will be released within these rock mass areas each time rock mass strengths are exceeded by the induced stress changes related to mining operations. This paper presents a discussion on how to predict the location of seismic activity areas based on a change of position of seismic energy equivalents. This parameter is calculated for a given set of seismic tremors with defined foci coordinates. For a given set of seismic tremors, the location of seismic energy equivalents may be used for predicting the location of high-energy seismic events.

Aug 1, 2013

By Dong-kil Lee

A ventilation improvement index (VII) was developed in an effort to propose an optimal ventilation improvement measure for a designated mine. The index was designed to incorporate both ventilation effectiveness and cost efficiency. To verify the effect of the index, a mine experiencing a ventilation problem was selected, the ventilation assessed and ventilation network analyses were conducted. In the selected mine, four areas with ventilation difficulties were detected and an improvement schemes for each area were proposed. These were simulated through network simulation and evaluated using the ventilation improvement index. As a result, an optimum ventilation improvement scheme was proposed. The improvement scheme with the highest VII value was incorporated in the design.

Aug 1, 2013

By S. M. Moon

Today, underground exploration is spotlighted as an infinitely developable area. For this purpose, many tunneling technologies were created. And until this very day, many techniques are being developed for more efficient underground movement. Although previous technologies have been developed and now being used in various forms like TMB, struck propulsion method and hydraulic propulsion method, it is hard to find a robot type exploring in small scale. But development of small scale underground exploration robot is a promising research subject for its usage in examination of soil, mineral, and subterranean resources, investigation of hazardous regions, and the military. So we developed a robot that can dig and move underground, inspired from the motion of earthworm and mole cricket. Earthworm and mole cricket dig the soil in the front and draw it off backward, so that they can move forward. We developed a mechanism that uses 2 rotating solid of revolution (bits) for pulverizing the firmly united soil in the front and put it inside the body. The bits rotate in the opposite direction of each other. While moving forward, the soil in the front moves along the spiral on the bit and is saved inside the body. The soil saved inside is taken out through an outlet in the back by a ventilation system. The ventilation system on the ground blows through a hosepipe connected to inner part of the robot and the air blows off the soil. The moving mechanism of exploring underground can be classified into 2 parts. One is to fix the blade link on the soil in a form of 4-bar link. The other one is to move forward rotating the whole link. When the blade link system for movement rotates a certain degree, one blade link is fixed, while the other one is folded in. When 2 blade links of different length rotate as it is, different torque is applied on each link. By the law of action and reaction, the link that has larger torque leads the rotation and movement.

Aug 1, 2013

By L. C. Lien

Tower crane layout (TCL) is a typical construction site layout (CSL) problem, which is suitable for a wide range of work assignments and site conditions. Tower crane is one of the key facilities for vertical and horizontal transportation of materials, especially for heavy prefabrication units such as steel beams, ready mixed concrete, prefabricated elements and large panel formwork such as machinery and equipment, and a wide variety of other building materials within a construction site. However, it is a difficult combinatorial optimization problem to determine the locations of tower cranes with materials quantity supply and demand for engineers. Swarm intelligence (SI) was very popular and widely used in many complex optimization problems which was collective behaviour of social systems such as honey bees (bee algorithm, BA) and birds (particle swarm optimization, PSO). This study applied a hybrid swarm algorithm namely particle bee algorithm (PBA) based on a particular intelligent behaviour of honey bee and bird swarms by integrates theirs advantages. This study compares the performance of PBA with BA and PSO for a proposed hypothetical construction engineering of TCL with materials quantity supply and demand problem. Results show that PBA performs better performance than the mentioned algorithms on a proposed hypothetical TCL problem.

Aug 1, 2013

By G. Tozsin

A six-stage sequential leaching procedure was used to assess the leachability of heavy metals from waste rock in Antamina Mine. Sequential extractions procedure is well established for fine and small (? 1g) samples. However procedures for coarse and large test samples are lacking. This study presents results of the sequential leaches tests conducted on relatively coarse and large representative samples in terms of the availability and mobility of metals. Selective chemical reagents were used to extract metals from six different fractions where metals released with each subsequent extraction are believed to be bound tighter than those released in prior steps and therefore less likely to be leached.

Aug 1, 2013

By M Safa

Addressing deficiencies and defects that occur during construction projects is costly and time consuming. The manual quality assurance programs currently used in the industry have certain limitations, including human error and lack of consistency. Hence, there is a need for integrated electronic models that employ new technologies and methods. This research introduces an integrated construction quality control system that has the potential to improve quality management processes in the construction field for piping construction, which is a complex process often requiring rework. The proposed integrated system relies on data collected from construction sites using photogrammetry and laser scanning, which is then used to compare actual work performed to that designed. The proposed system aims to improve the promptness and accuracy of quality assurance processes, in particular dimension measurements, by avoiding human error and integrating defect detection and quality management. The use of this system has highlighted some of the limitations during data fusion and acquisition process, which are highlighted in this paper. These aspects must be considered to increase the reliability of the acquired information.

Aug 1, 2013