132 research outputs found

    Investigation of direct drive hydraulics implemented in mining loader

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    The conventional mining loader is a diesel-hydraulic off-road mobile machine that is expected to routinely operate in enclosed areas. Such machines could benefit from more efficient hydraulic solutions. One avenue of improvement lies in electrification, which in itself is advantageous to underground mining machinery that would otherwise require expensive ventilation of their ICE exhaust. The high controllability of brushless DC motors allows direct pump control instead of conventional valve control, eliminating throttling losses. This work investigates the efficiency of such a direct-driven valveless hydraulic system for the front end of a mining loader and compares it to a conventional load-sensing system that was previously installed in the same machine. Economic viability of the described system is analyzed based on a real life working cycle, and the control software implemented as part of the work is described. The efficiency of the direct-driven system was determined to be superior in all tested cases, increasing from 21% to 53% at high velocity and from 2% to 22% at low velocity and maintaining a very flat efficiency curve over most loads and velocities. The direct drive hydraulic system is capable of energy regeneration, recouping a portion of energy used for lifting thus allowing longer runtimes with a given battery capacity. These advantages were found to be enough to offset the higher up-front cost except for equipment with lower than usual lifespans.Kaivoslastarit ovat usein dieselhydraulisia työkoneita, jotka monesti toimivat maanalaisissa kaivoksissa. Sähkökäyttöiset toimilaitteet ovat yksi mahdollinen tapa parantaa näiden koneiden energiatehokkuutta, eteenkin suljetuissa tiloissa, joissa polttomoottorin pakokaasujen tuulettamisesta aiheutuu huomattavia kustannuksia. Sähkömoottoreiden hyvä hallittavuus mahdollistaa venttiilittömän pumppuohjatun hydraulijärjestelmän, joka ei kärsi venttiilihäviöistä. Tämä työ vertailee pumppuohjattuja suoravetohydraulisia kaivoslastarin toimilaitteita saman lastarin alkuperäisiin kuormantuntevalla säädöllä toteutettuihin, keskittyen hyötysuhteeseen sekä suorituskykyyn. Näin muokatun lastarin taloudellista kilpailukykyä tarkastellaan oikean kaivostyösyklin avulla. Työn osana on myös rakennettu kaivoslastarin toimilaitteinen sähköinen hallintajärkestelmä, jonka rakenne ja toiminta esitetään. Pumppuohjatun hydraulisen järjestelmän hyötysuhteen havaittiin olevan nostotyössä parempi kaikissa tilanteissa hyötysuhteen noustessa nopeilla liikkeillä 21 prosentista 53:een, ja hitailla liikkeillä 2 prosentista 22:een. Pumppuohjattu hydrauliikka kykenee myös potentiaalienergian talteenottoon, mahdollistaen pidemmän käyntiajat samalla akkukapasiteetilla. Nämä edut ovat taloudellisesti riittäviä kompensoimaan laitteiston korkeamman hinnan lyhytikäistä kalustoa lukuunottamatta

    Energy Management of an Autonomous Electric Hauler

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    Engineering economic analysis of a rail extension from Dunbar siding to Livengood, Alaska

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    Thesis (M.S.) University of Alaska Fairbanks, 2011The Dunbar Siding to Livengood rail extension study is an economic prefeasibility investigation, and is conducted from two perspectives as a cost benefit analysis. The first perspective is, that of the Alaska Railroad Corporation (ARRC) in which the capital and operating costs of the proposed extension are recovered through the revenue stream resulting from the out-bound mineral freight loads, the in-bound re-supply freight loads, and the potential commuter passenger service to mining projects and communities in the Livengood area. The second perspective is that of the private sector in which a shipping sensitivity and employee transport analysis with respect to mining project developments. The large mineral resource base within the Dunbar-Livengood Corridor indicates an excellent freight potential with generous benefits for Alaska's economy of greater than $2 billion annually in gross revenues; whereas, resource and rail development are synergistic.Alaska Department of Transportation/Public Facilities1.0. Introduction -- 1.1. Opening -- 1.2. Foreground -- 2.0. Location and geologic hazards -- 2.1. General route setting -- 2.2. Bedrock geology -- 2.3. Surficial geology -- 2.4. Seismicity -- 2.5. Aufies/Icings -- 2.6. Frozen ground -- 3.0 History -- 3.1. Brief history of the Alaska Railroad -- 3.2. History of mining in Livengood -- 4.0. Methods and models -- 4.1. Freight modeling summary -- 4.2. ARRC model -- 4.3. Initial rail operation cost estimates -- 4.4. Final rail operation cost estimates -- 4.5. Freight sources -- 4.5.1. ITH, money knob project freight model -- 4.5.2. Shorty Creek project -- 4.5.3. Globe Creek limestone project -- 4.5.4. Probable prospects -- 4.5.5. Ore prospect tonnage model -- 4.5.6. Timber resources -- 4.5.7. Tourism -- 4.5.8. Truck freight -- 4.6. Rail freight model results -- 5.0. Livengood money knob project mine model -- 5.1. Introduction to Money Knob project model -- 5.2. Pit costs -- 5.3. Heap leach costs -- 5.4. Mill (floatation) costs -- 5.5. Gravity recovery circuit cost -- 5.6. Cyanide agitated leach costs -- 5.7. Carbon in pulp costs -- 5.8. Electric power -- 5.9. Trolley assisted haul summary -- 5.10. Mine model cash flow analysis -- 5.11. Mine modeling results, at specific tonnages -- 6.0. Economic benefits -- 7.0. Cost benefit analysis -- 7.1. ARRC perspective -- 7.2. Public perspective 7.3. Cost benefit results -- 8.0. Discussion -- 9.0. Conclusions and recommendations 9.1. Conclusions -- 9.2. Recommendations -- 10.0. References -- Appendix

    Development of a Computer Oriented Algorithmic Approach for Opencast Mine Dispatch System

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    Truck haulage is the most common means used for moving ore/waste in open-pit mining operations, but it is usually the most expensive unit operation in a truck shovel mining system. The state-of-the-art in computing technology has advanced to a point where there are several truck dispatching systems which offer the potential of improving truck-shovel productivity and subsequent savings. Introducing a dispatching system in a mine can achieve operational gains by reducing waiting times and obtain other benefits through better monitoring, optimal routing and grade control. Efficiency of the employed truck-shovel fleet depends on the dispatching strategy in use, the complexity of the truck-shovel system and a variety of other variables. It is a common situation in mining that considerable analysis of the available strategies is undertaken before dispatching is adopted. In most cases, computer simulation is the most applicable and effective method of comparing the alternative dispatching strategies. To develop a computer based algorithm for despatch systems in open cast mines, the program asks the user to enter the number of trucks initially assigned to each shovel site. Experiments are made to investigate the effects of several factors including the dispatching rules, the number of trucks operating, the number of shovels operates, the variability in truck loading, hauling and return times, the distance between shovels and dump site, and availability of shovel and truck resources. The breakdown of shovel and trucks are modeled using exponential distribution. Three performance measures are selected as truck production, overall shovel utilization and overall truck utilizations. But, the main factors affecting the performances are the number of trucks, the number of shovels, the distance between the shovels and dump site, finally the availability of shovel and truck resources. Also, there are significant interaction effects between these main factors

    The Application of Major Hazard Risk Assessment (MHRA) to Eliminate Multiple Fatality Occurrences in the US Minerals Industry

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    Major Hazard Risk Assessment (MHRA)1 is used to help prevent major hazards, e.g., fire, explosion, wind-blast, outbursts, spontaneous combustion, roof instability and chemical and hazardous substances, etc., from injuring miners. The structured process associated with MHRA helps to characterize the major hazards and evaluate engineering, management and work process factors that impact how a mine mitigates its highest risk. The National Institute for Occupational Safety and Health (NIOSH) studied the application of this technique to US mining conditions through a field-oriented pilot project. Risk assessment teams used in the pilot project were primarily composed of mining company personnel. Ten case studies were performed over a wide cross-section of mines. These mines were representative of the important mining commodities in the US minerals industry, i.e. coal, metal, non-metal, and aggregate. Also, the sizes of the mines ranged from small to large and were located across the country. The ten case studies demonstrate that most US mines have the capability to successfully implement an MHRA and that the MHRA methodology produced additional prevention controls and recovery measures to lessen the risk associated with a select population of major mining hazards. The basic ingredient for a successful MHRA is the desire to become more proactive in dealing with the risks associated with events that can cause multiple fatalities. A successful outcome is marked by a thorough examination of existing prevention controls and recovery measures. When pressed to consider more controls to further mitigate the risk, a well-staffed risk assessment team was able to identify additional controls. For these mining operations, it was important to add additional controls, even if they were not required by existing mining regulations, to lower the risks associated with the major hazards under consideration. If a mining operation is not willing to commit its best people to an MHRA or will not provide them with sufficient time to see the process through to its conclusion, the MHRA output may prove to be useless. Additionally, if a mining operation is not prepared to discuss its major hazards in an open and honest fashion and to present the findings of the risk assessment in a written report, the MHRA output will be unclear, and attempts to monitor or audit important controls may not be possible. A MHRA is most effective when the mining operation possesses 1) a proper understanding of its hazards, 2) experience with informal and basic-formal risk assessment techniques, 3) proper facilities, machinery and equipment, 4) suitable systems and procedures that represent industry Best Practice, 5) appropriate organizational support with adequate staff, communications and training, 6) a formal and thorough plan for emergency response, and 7) a safety risk management approach that is promoted and supported at all levels of the organization

    The Application of major hazard risk assessment (MHRA) to eliminate multiple fatality occurrences in the U.S. minerals industry

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    "Major Hazard Risk Assessment (MHRA) is used to help prevent major hazards, e.g., fire, explosion, wind-blast, outbursts, spontaneous combustion, roof instability and chemical and hazardous substances, etc., from injuring miners. The structured process associated with MHRA helps to characterize the major hazards and evaluate engineering, management and work process factors that impact how a mine mitigates its highest risk. The National Institute for Occupational Safety and Health (NIOSH) studied the application of this technique to US mining conditions through a field-oriented pilot project. Risk assessment teams used in the pilot project were primarily composed of mining company personnel. Ten case studies were performed over a wide cross-section of mines. These mines were representative of the important mining commodities in the US minerals industry, i.e. coal, metal, non-metal, and aggregate. Also, the sizes of the mines ranged from small to large and were located across the country. The ten case studies demonstrate that most US mines have the capability to successfully implement an MHRA and that the MHRA methodology produced additional prevention controls and recovery measures to lessen the risk associated with a select population of major mining hazards. The basic ingredient for a successful MHRA is the desire to become more proactive in dealing with the risks associated with events that can cause multiple fatalities. A successful outcome is marked by a thorough examination of existing prevention controls and recovery measures. When pressed to consider more controls to further mitigate the risk, a well-staffed risk assessment team was able to identify additional controls. For these mining operations, it was important to add additional controls, even if they were not required by existing mining regulations, to lower the risks associated with the major hazards under consideration. If a mining operation is not willing to commit its best people to an MHRA or will not provide them with sufficient time to see the process through to its conclusion, the MHRA output may prove to be useless. Additionally, if a mining operation is not prepared to discuss its major hazards in an open and honest fashion and to present the findings of the risk assessment in a written report, the MHRA output will be unclear, and attempts to monitor or audit important controls may not be possible. A MHRA is most effective when the mining operation possesses 1) a proper understanding of its hazards, 2) experience with informal and basic-formal risk assessment techniques, 3) proper facilities, machinery and equipment, 4) suitable systems and procedures that represent industry Best Practice, 5) appropriate organizational support with adequate staff, communications and training, 6) a formal and thorough plan for emergency response, and 7) a safety risk management approach that is promoted and supported at all levels of the organization." - NIOSHTIC-2by A. Iannacchione, F. Varley and T. Brady."October 2008."Also available via the World Wide Web.Includes bibliographical references (p. 121-122)

    Best practice for personnel, material and rock transportation in ultra deep level gold mines.

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    Thesis (Ph.D.)-University of Natal, Durban, 2003.Ultra deep mining presents many challenges to the mining engineer, one of which is the logistics to support mining operations quickly and efficiently. Typically, Witwatersrand gold mines operate at depths in excess of 2000 m with stoping taking place to 3500 m and investigations underway to mine to a depth of 5000 m. As mining progresses deeper and further from the shaft, the role of logistics becomes increasingly important if production targets are to be achieved. Access to the workings is often via sub vertical and even tertiary subvertical shaft systems with working faces as far as five kilometers from the shaft. It is inevitable therefore, that distance will negatively impact the working time available at the stope face, material transportation and distribution, as well as the removal of broken ore. Possible solutions to these logistical problems may be found in the use of different transportation systems or by applying sound design and operational principles to transportation systems, both in the horizontal and instope areas. This thesis investigates the challenges of logistics for ultra deep level gold mining in the Witwaterstrand basin for mining layouts planning to mine between 3000 m and 5000 m underground with typical horizontal distances of over 3000 m. The transportation needs analysis recognised that vertical transportation is a wellmanaged and organised system and is mainly the same for both shallow and deep level operations. As a result of this, the thesis only focuses on the logistical issues of the horizontal and in-stope processes. The literature review indicates that the majority of work previously conducted on transportation focused around the area of horizontal transportation with limited inputs to in-stope transportation systems. The review concludes that the traditional locomotive transportation system is the most applicable mode of horizontal transportation. Thus, special emphasis is given to trackbound transportation. An integrated approach is taken towards mine transportation advocating that underground logistics be considered as equally important as any other discipline, Le. rock engineering, ventilation, etc. In addition, the transportation process should consider each area equally important. All to often, the transportation of rock is considered of paramount importance over the transportation of personnel and material. Thus, the planning any transportation system should incorporate personnel, material and rock. To enable this, scheduling, communication and control are important with special attention required for transfer points in the transportation system. As each site has its own particular requirement, thus the final transportation systems must be drawn up based on the specific requirements of each mine. A guideline is proposed for the design of ultra deep level underground transport systems for personnel, material and rock transportation. Thus, providing mining engineers with sufficient information and data to select an appropriate transportation system to meet specific mine requirements. The thesis highlights areas requiring consideration by mine engineers when designing a transportation system from shaft to the working face
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