Analyzing the Electricity Consumption and Costs of Electrical-Powered Machines When There is Orepass Failure in Underground Mine

AbstractIn underground mining environment where the loss of orepasses is a dominant factor, the mine may face a challenge of improving the loading and hauling operations. Some of the options will be to rehabilitate the lost orepasses, or developing the new ones. When the rehabilitation cost is high, alternative strategies should be applied to compensate for the orepasses failure. One of the possible options is to use diesel or electric Load-Haul-Dumps (LHDs). The use of diesel-powered LHDs will increase heat and gas emissions which increase environmental concerns and ventilation costs, while adoption of electric-powered vehicles needs to be analysed. Therefore, this study was conducted at an existing underground mine in Sweden, to determine the electricity consumption and costs of electric-powered LHDs when there is a loss of orepasses. The AutoModTM discrete event simulation tool was used during the analysis. The results show that, electric-powered LHDs have significant cost saving when used in case of orepass loss to move materials compared to diesel-powered units. However, the source of electricity to fully adopt electric-powered units may need further financial justifications to evaluate the impacts to the environment. Keywords: Electricity costs; production rate; discrete event simulation; loading operations

Underground mining of aggregates. Main report

This report examines the economic feasibility of underground mining for crushed rock aggregates in the UK, but particularly in the London, South East and East of England regions (the South East area of England). These regions import substantial volumes of crushed rock, primarily from the East Midlands and South West regions, requiring relatively long transport distances to market for this bulk commodity. A key part of the research was to determine whether or not aggregate could be produced and delivered to a local market from an underground aggregates operation at a cost comparable with that for production and transport of the commodity from traditional surface quarries located further afield. In essence the investigation asked – could the reduced transport costs compensate for the higher production costs underground so that underground crushed rock aggregates producers can compete with the established Leicestershire and Somerset surface quarries exporting to the South East? Work Programme The research effort involved establishing and verifying cost models for aggregates production, stone processing (sizing and sorting), haulage of product to market, environmental impact mitigation, health and safety, decommissioning and restoration. Another major element of the work was the re-examination of the BGS exploratory borehole and geophysical databases to identify potential areas of crushed rock aggregates resource at depth in the South East area of England. Land use pressure is typically higher in this area of England than elsewhere so another major part of the research was the identification of potential concurrent uses of land around the surface facilities of underground aggregates mines. The value, development costs for specific developments and determination of yields expected, from these uses were estimated. These were also used to investigate potential economic benefits associated with after uses of remediated surface land above potential underground aggregates mines and also for the new underground space that would be created. Key technical issues such as subsidence within relatively heavily populated areas of the South East area of England were also addressed. Economic Results The discounted cost of aggregate delivered at a discount rate of 10% was the metric used to appraise the options. This is the price of aggregate that leads to a zero net present value of project cash flows realised over the aggregates project life. The results show that the discounted costs of aggregate delivered to a local South East area of England market from an underground mine producing 3.5 million tonnes per annum (MTPA) of crushed rock aggregates, are in the range of £13.03 per tonne to £13.93 per tonne for the top six prospect locations. These are greater than the corresponding cost for a “reference” quarry in Leicestershire producing 3.5 MTPA (£10.95 per tonne), but lower than a “reference” quarry in Leicestershire producing 1.25 MTPA (£16.48 per tonne). These figures indicate that underground crushed rock aggregate mines located within the South East area of England may be able to compete for a share in the overall market by replacing / displacing aggregate imported from the quarries in Leicestershire and Somerset producing around or less than 1.25 MTPA. The surprise in these figures is not really that the more remote surface quarry has a lower discounted cost of aggregate delivered, but that the values for the quarry and underground mine are so close. The capital intensity for the development of underground aggregates mines was found to be higher than that required for surface quarries of comparable scale, by a factor ranging from 1.33 to 1.65 and thus may represent a disincentive for aggregates operators. Carbon Emissions The total carbon emissions of the ‘reference’ 3.5 MTPA quarry in Leicestershire were estimated at 9.28 kg CO2/tonne aggregate delivered and this is to be compared with carbon emissions for the 150 metre deep underground mines serving the local market which were estimated at 9.31 kg CO2/tonne delivered for a Bletchley prospect using an adit to access the sub-surface and 14.25 kg CO2/tonne delivered for a prospect based on the Chitty bore hole using a shaft. Depth of the mine is a key factor in determination of the relative carbon emissions from each of the underground mining operations considered as electricity consumption for ventilation, pumping and winding is proportional to depth. Recommendations The current research generated seven principal recommendations which are discussed in detail in the concluding section of the report. These are: Appraise policy incentives for underground aggregates mining. Conduct an industry-wide consultation on findings from the current research. Obtain public and stakeholder opinion on new uses for underground space. Conduct research to reducing the energy intensity of mine services. Develop a deep level aggregates-specific drilling campaign. Investigate underground aggregates mines developed from existing surface quarries. Investigate underground aggregates as co-products of industrial minerals mining

Energy Consumption Optimization of Powertrain of Electric Underground Load-Haul-Dump Mining Loader

The emissions of heavy-duty underground machinery endanger the health of human workers and increase the overall maintenance cost of the underground mine due to ventilation expenses. In addition, tightening emission standards for non-road vehicles are pushing towards greener solutions, hence, fully electric powertrains are becoming a viable alternative for many applications. An electric powertrain is not only local emission-free, but also provides a better controllably and a superior energy efficiency compared to the conventional diesel operated machines. The nature of such vehicles and their periodic duty cycles enable energy optimization and a prospect of an improved efficiency. The aim of the thesis was to reduce the energy consumption of an underground load-haul dump mining loader. As most of the energy is consumed by the powertrain of the vehicle, the traction motors are the focus of the optimization. An optimal speed profile was generated by means of Bellman’s dynamic programming algorithm in MATLAB environment. The simulation utilized dynamic asynchronous motor, battery and vehicle models built according to a real-size experimental prototype. The algorithm had been designed to solve discrete time problems; therefore, the model was discretized with adjustable dynamic accuracy where the intermediate points were obtained by linear interpolation. The optimal speed profile demonstrated a 9.1% decrease in energy consumption for a generic duty cycle. Additionally, the asynchronous motors were operated at a higher efficiency area generating less heat and in theory prolonging the lifetime of the powertrain components

Investigation of direct drive hydraulics implemented in mining loader

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

Evaluation of the thermal impact from battery packs from electrical vehicles in underground mining environment

One of the main aspects which governs the size of ventilation facilities in underground mines is the amount of heat load generated in the underground environment. This heat load comes from many different sources, one of which is the heat contributed by underground diesel machinery operation. One strategy to mitigate the heat and other emissions from such equipment is to substitute these units to similar performance, but more thermally efficient, electric machinery. This study presents a heat load evaluation of the Lithium-iron Phosphate battery system used in a prototype electric mining vehicle. The set of equations which governs the heat generation from these devices have been developed by previous researchers and is used in this thesis to calculate the heat generation and loss. However, in the mining industry, the current methodology for heat load calculation from electric vehicles (EVs) is usually based on the rated power or on a simple power loss equation. This strategy might lead to incorrect estimations of the heat load from this type of machinery. Experimental and simulation work has been conducted as a means to evaluate the heat flux from the Lithium-iron Phosphate battery system. The battery was tested through charging and discharging it under different levels of current within the 10% to 90% range of its maximum capacity. The test was performed firstly with a single cell and then with a module. Furthermore, the battery system was set in operation under different environment temperature settings. These current and temperature levels represent the range of possible conditions in which the prototype will face in service. Through the estimation of the heat released from the other main electrical components in the vehicle, it was possible to calculate the heat impact of these units in the surrounding environment.Master of Applied Science (M.A.Sc.) in Natural Resource Engineerin

Ecological and economic evaluation of quarry trolley trucks

Open-cut mining is the main way to extract minerals. Up to 80% of the rock mass produced by that is transported by dump trucks with diesel engines. Atmospheric gas pollution is an essential disadvantage of using diesel vehicles, especially in deep formations. Exhaust gases from diesel vehicles have a detrimental effect on human health and the environment. Constant exposure of exhaust gases on the body can cause immune deficiency, bronchitis, cerebral vessels and nervous system suffer. The higher the depth of mining the higher the concentration of machinery on formations and the worse the conditions of natural ventilation of the working space. At the depth of quarries over 200–250 m air pollution by harmful substances at the workplace leads to a gradual increase of the maximum permissible concentrations. That affects both people and economy of the enterprise since it entails the necessity to shut the career down, deteriorate visibility on the highway, which also causes a partial or total suspension of equipment operation. Transfer of dump trucks to electricity is a prospect way to solve the problem. Together, all the positive qualities of trolley trucks reduce the maintenance costs of transportation of rock mass by 15–20%, as well as exclude the gassing of the quarry and formation of smoke. Need for power from the contact network is the most serious drawback of trolley truck. Today, thanks to modern technologies, eliminating most of the drawbacks of trolley trucks is not difficult. Quarry trolley trucks are better used only for long-term development, since the content of the trolley line contact requires attendance and maintenance. The payback period can be 2–4 years

Energy efficiency and carbon dioxide emissions across different scales of iron ore mining operations in Western Australia

During the last two decades, Western Australian iron ore mining industry experienced an exponential production growth arising from increased global demand for steel. The upturn in the iron ore price and considerably lower production cost encouraged extensive mining and consequently high-grade ore reserves were gradually depleted. Despite the energy-intensive nature of mining, high profitability motivated the mining companies to extract marginal-grade deposits with additional processing requirements, which increased energy consumption and ultimately increased the cost of iron ore production. This thesis sought to identify the energy efficiencies of open-cut iron ore mining operations, in terms of scale of operation as well as within individual mining processes, so that energy consumption could be reduced, and sustainability enhanced. Efficiency indices were used to determine energy efficiency across different scales of operation. Overall energy consumption (per unit of processed ore) was directly related to the scale of operation, where large-scale mining operations are more energy efficient compared to medium and small scales requiring the lowest amount of energy to process a unit of ore. This suggests that an economy of scale based on energy efficiency can be observed in iron ore mining operations. Small-scale mining operations recorded the highest energy consumption to process a unit of ore, indicating the lowest energy efficiency among the three different scales of operation. However, the composite energy indicator indicated that the energy efficiency of a particular mining operation is also influenced by the geological and physical parameters of individual factors including the waste-ore ratio, grade of ore, average haulage distance and production capacity. The results of the regression analysis confirmed that it is the combined effect of all the aforementioned parameters that has a pronounced effect on the amount of energy consumed to process a unit of ore. Energy consumption per unit of processed ore at different process stages revealed that the loading and hauling phase is the most energy intensive process stage in an iron ore mining operation regardless of the scale at which it is operating. The milling and stockpiling phase was the second highest energy consuming process stage, while the drilling and blasting phase was the subsequent energy demanding process stage in iron ore mining operations. Small-scale operations recorded a higher energy consumption in loading and hauling than the medium-scale operations, suggesting that the equipment with high load capacities and energy efficient technologies such as overland conveyor belts, and advanced technologies including autonomous haulage trucks resulted lower energy consumption in medium scale mining operations. However, the energy consumed to mill and stockpile a unit of ore in medium-scale operations was high compared to the small-scale operations, suggesting that the energy consumption in milling and stockpiling is mainly influenced by the properties of the mill feed, such as moisture content. Further, the amount of processing needed to achieve sufficient final product quality can also influence energy consumption. Findings from this study support the idea that an economy of scale can be observed across iron ore mining operations in Western Australia based on energy efficiency. The study also provided essential baseline information for future studies on the variations in energy efficiency across different iron ore mining operational scales in Western Australia

A Compendium of NIOSH mining research, 2001

"To continue serving the safety and health needs of the Nation's miners, NIOSH is coordinating extensively with stakeholders across the country to obtain valuable insight into their priorities. This input, together with results from comprehensive analyses of safety and health data, has allowed us to begin balancing the mining research program to address the prioritized needs of miners in various industry sectors. This publication provides brief descriptions of the NIOSH projects dedicated to the primary mission of reducing miners' occupational injury and illness including: hearing loss prevention; dust measurement and control; diesel emissions and toxic substances; hazard detection and warning devices; injury prevention and equipment design; training and education; ground control; fires, explosions, and ventilation; surveillance; and emerging technologies. The breadth and quality of research represented here is a true testament to the dedicated NIOSH researchers working in this field. As problems and issues emerge, or are effectively addressed over time, the research program will change accordingly, but it will continue to be based on a solid, scientific rationale and anchored in reality. NIOSH is always looking for better ways to communicate our research and results. This publication is just one way we are reaching out to inform our mining partners and other interested individuals and organizations about our current mining research projects. I look forward to continued interaction with NIOSH's many mining partners " - NIOSHTIC-2NIOSTIC no. 20000979Spokane Research Laboratory and Pittsburgh Research Laboratory.Includes bibliographical references

Design criteria for an autonomous, electric mine

This collaborative master's thesis was conducted in partnership with Boliden AB and centers on providing design criteria for the main orebody located below 1000 meters in Garpenberg's mine, with the aim of enabling the use of autonomous and electrified machinery. Furthermore, based on the identified criteria, new designs for this orebody are generated. Presently, Boliden's mining operations utilize manual and semi-autonomous, diesel-operated machines; however, the company's objective is to transition to electric machines that can operate autonomously or remotely from a control room. Consequently, the current mine infrastructure of operating mines must be integrated, and new mines not yet in production must be designed to accommodate the needs of autonomous and electrified machines, to optimize mining processes. This transition necessitates a substantial amount of additional mining infrastructure, compared to a conventional mine, employing manual operations of diesel-operated machinery. The construction of charging stations for Battery Electric Vehicles (BEVs) or infrastructure for cable-electric vehicles is essential. Additionally, methods for utilizing the regenerative braking of electric vehicles (EVs) should be examined and changes in opening dimensions and road conditions may be necessary to optimize the use of autonomous equipment. Moreover, the possibility of combining manned and unmanned vehicles in the same area, as well as an increased power supply, may also require consideration. The objective of this thesis is to outline the design criteria for an autonomous and electric underground mine, create two new designs, and compare them to the current one using work cycle simulations of LHDs and trucks, ultimately selecting the most efficient design. The thesis yields three major contributions: first, it establishes design guidelines for an autonomous and electric mine; second, it introduces two innovative designs labeled as "V" and "W," specifically adapted to meet the new criteria; and third, it conducts a comparative analysis of the designs. The analysis involves work cycle simulations of loaders and trucks for different scenarios, comparing the current design with the two new designs to determine the most efficient option