Assessment of alternative power sources for mobile mining machinery

Alternative mobile power sources for mining applications were assessed. A wide variety of heat engines and energy systems was examined as potential alternatives to presently used power systems. The present mobile power systems are electrical trailing cable, electrical battery, and diesel - with diesel being largely limited in the United States to noncoal mines. Each candidate power source was evaluated for the following requirements: (1) ability to achieve the duty cycle; (2) ability to meet Government regulations; (3) availability (production readiness); (4) market availability; and (5) packaging capability. Screening reduced the list of candidates to the following power sources: diesel, stirling, gas turbine, rankine (steam), advanced electric (batteries), mechanical energy storage (flywheel), and use of hydrogen evolved from metal hydrides. This list of candidates is divided into two classes of alternative power sources for mining applications, heat engines and energy storage systems

Optimization of blasting parameters in opencast mines

Drilling and blasting are the major unit operations in opencast mining. Inspite of the best efforts to introduce mechanization in the opencast mines, blasting continue to dominate the production. Therefore to cut down the cost of production optimal fragmentation from properly designed blasting pattern has to be achieved. Proper adoption of drilling and blasting can contribute significantly towards profitability and therefore optimization of these parameters is essential. Introduction Rock breaking by drilling and blasting is the first phase of the production cycle in most of the mining operations. Optimization of this operation is very important as the fragmentation obtained thereby affects the cost of the entire gamut of interrelated mining activities, such as drilling, blasting, loading, hauling, crushing and to some extent grinding. Optimization of rock breaking by drilling and blasting is sometimes understood to mean minimum cost in the implementation of these two individual operations. However, a minimum cost for breaking rock may not be in the best interest of the overall mining system. A little more money spent in the rock-breaking operation can be recovered later from the system and the aim of the coordinator of the mining work should be to achieve a minimum combined cost of drilling, blasting, loading, hauling, crushing and grinding. Only a “balance sheet” of total cost of the full gamut of mining operations vis-à-vis production achieved can establish whether the very first phase- rock breaking- was “optimum” financially; leaving aside factors of human safety. An optimum blast is also associated with the most efficient utilization of blasting energy in the rock- breaking process, reducing blasting cost through less explosive consumption and less wastage of explosive energy in blasting, less throw of materials, and reduction of blast vibration resulting in greater degrees of safety and stability to the nearby structures. Development of a Blast Optimization Model Selection of proper explosive in any blasting round is an important aspect of optimum blast design. Basic parameters include VOD of explosive (m/s), Density (g/cc), Characteristic impedance, Energy output (cal/gm), and Explosive type (ANFO, Slurry, Emulsion etc.). However, all these parameters can not be taken for optimizing the blasting method successfully. Some of the parameters are taken for minimizing the blasting cost. These cost reduction and optimum blast design parameter will give an economical result. The parameters are i. Drill hole diameter, ii. Powder factor (desired), iii. Cost of explosive, iv. Numbers of holes required to blast. Methodology The study of the various parameters of blasting suggests that the powder factor should be constant as per the requirement. The number of holes desired as per the explosive, the drill ihole diameter as available and the cost of explosive are kept as input. The spacing, bench height, burden, charge per hole as depending on the previous parameters can be calculated. From the different input and calculated parameters the total cost of the method is calculated and the least expensive method is selected as the optimized model. Blasting related information were collected from three different mines of Mahanadi Coalfields Ltd.(MCL) for implementation of the optimization model. A program was designed using visual basic on .net platform taking the above parameters into consideration to select the optimized model. It was observed that the program gives satisfactory results. A sample output of the program is as presented below: Conclusion The blast optimization model has been developed with simple methodologies which can be adopted by the mining industry to compare the explosive costs and achieve better blasting results and. The model developed is a user friendly one, since by keeping the powder factor and number of choices of explosives available as constant and by varying the parameters like drill hole diameter, number of holes and cost of explosives one can compare the explosive performance and accordingly take a decision to select the proper type of explosives for blasting. It may be noted, that the model has been developed based on case studies of three different mines of MCL, and it can be modified with collection of information from a large number of mines. References Nanda, N.K. (2003), “Optimization of mine production system through operation research techniques”, 19 th World Mining Congress, New Delhi, November, pp.583-595. Pal Roy, P. (2005), “Terms and parameters influencing mine and ground excavations”, Rock blasting effects and operations, pp. 17-22

Automation of the longwall mining system

Cost effective, safe, and technologically sound applications of automation technology to underground coal mining were identified. The longwall analysis commenced with a general search for government and industry experience of mining automation technology. A brief industry survey was conducted to identify longwall operational, safety, and design problems. The prime automation candidates resulting from the industry experience and survey were: (1) the shearer operation, (2) shield and conveyor pan line advance, (3) a management information system to allow improved mine logistics support, and (4) component fault isolation and diagnostics to reduce untimely maintenance delays. A system network analysis indicated that a 40% improvement in productivity was feasible if system delays associated with all of the above four areas were removed. A technology assessment and conceptual system design of each of the four automation candidate areas showed that state of the art digital computer, servomechanism, and actuator technologies could be applied to automate the longwall system

Preliminary power train design for a state-of-the-art electric vehicle

Power train designs which can be implemented within the current state-of-the-art were identified by means of a review of existing electric vehicles and suitable off-the-shelf components. The affect of various motor/transmission combinations on vehicle range over the SAE J227a schedule D cycle was evaluated. The selected, state-of-the-art power train employs a dc series wound motor, SCR controller, variable speed transmission, regenerative braking, drum brakes and radial ply tires. Vehicle range over the SAE cycle can be extended by approximately 20% by the further development of separately excited, shunt wound DC motors and electrical controllers. Approaches which could improve overall power train efficiency, such as AC motor systems, are identified. However, future emphasis should remain on batteries, tires and lightweight structures if substantial range improvements are to be achieved

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

Development of a mine hoist and ore pass research facility

"A hoisting and ore pass research facility was developed at the Spokane Research Center, Washington to assess methods for improving the safety of mine shaft and ore pass vertical movement operations. The technology available, including equipment used and sensor availability were assessed. The performance of hoist control equipment (hoist room controls, motors and gearboxes, and winders) and infrastructure (support frameworks, guides, wire ropes, and skips and cages), conveyance monitoring processes, and elevator control systems were also assessed. The information gathered contributed to the development of a new hoisting and ore pass testing facility, and improvements to the design of monitoring and data collection equipment. Critical hoist operating parameters such as conveyance position, conveyance speed and acceleration, load, rope tension, and shaft guide misalignment could be monitored and assessed. It was also possible to investigate the causes of ore pass blockages and to increase safety by detecting blockages and improving hang up removal methods." - NIOSHTIC-2Includes bibliographical references

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

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

Ground Robotic Hand Applications for the Space Program study (GRASP)

This document reports on a NASA-STDP effort to address research interests of the NASA Kennedy Space Center (KSC) through a study entitled, Ground Robotic-Hand Applications for the Space Program (GRASP). The primary objective of the GRASP study was to identify beneficial applications of specialized end-effectors and robotic hand devices for automating any ground operations which are performed at the Kennedy Space Center. Thus, operations for expendable vehicles, the Space Shuttle and its components, and all payloads were included in the study. Typical benefits of automating operations, or augmenting human operators performing physical tasks, include: reduced costs; enhanced safety and reliability; and reduced processing turnaround time

Analysis of end use electrotechnology in mining and minerals processing as a determinant for electricity growth with special reference to the RSA

A project report submitted to the Faculty of Engineering, University of Witwatersrand, Johannesburg, In partial fulfilment of the requirements for the degree of Master of Science in Engineering George, 1996. The history of electricity growth in South Africa. has been one of rapid growth.' This reached as high as 13%in one year with the increase in electrification of mining and lndustry from the -1960's to 1980ts. In addition the development of new mines and new minerals beneficiation plants, especially metals beneficiation, accelerated electricity growth due to the electricity intensive end use technologies implemented that were specific to those industriesGR 201

Evaluation of monorail haulage systems in metalliferous underground mining

The decline is a major excavation in metalliferous mining since it provides the main means of access to the underground and serves as a haulage route for underground trucks. However, conventional mining of the decline to access the ore body poses economic and technical challenges that require innovative responses. The average cross-sectional area of mine declines in Australia is 5m wide x 5m high. The large excavations associated with current underground mining practices are economically and geotechnically inappropriate, especially for narrow vein mining conditions. The decline gradient of 1 in 7 (8[superscript]o) designed to accommodate truck haulage results in a significantly longer decline compared to a decline mined at a steeper gradient. Further, the current drill-blast-load-haul cycle does not allow rapid development of the decline to access the ore body since the cycle is made up of discontinuous segments. The use of diesel equipment poses health risks and increases ventilation requirements. The heat load and air borne exhaust contaminants emitted by large diesel engines create heavy demand on mine ventilation, sometimes resulting in substandard working conditions. As mines get deeper, there is a tendency to increase the truck and loader fleet – which results in traffic congestion in the decline. Metal prices in the recent boom may have helped to offset some of the shortcomings of current practices, and although the good times may continue, a down-turn could find many operations exposed. Federal government emissions trading scheme encourage mining companies to reduce carbon emissions in their operations.This study was prompted by the need to investigate the potential of the monorail haulage system in metalliferous mining, particularly in decline development and main haulage in view of shortcomings of the current practices. Monorail systems are being used in mines around the world for material transport and man-riding but their utility in rock transport has not been fully investigated. Hence, it is proposed to replace non-shaft component of the mine haulage system with roof/back mounted monorail technology using continuous conductor technology to provide competitive haulage rates in substantially smaller excavations at steeper gradient than is currently achievable. It is proposed that a suite of equipment can be adapted or modified to enable development of the decline supported by the monorail system.To this end, a drill system mounted on the monorail accompanied by a pneumatic system for loading rock into monorail containers is proposed. The proposed decline gradient for the monorail decline is 1 in 3 (or 20[superscript]0) with a cross-sectional area of 4m wide x 4m high. Decline dimensions of size 4.0m x 4.0m (minimum opening for monorail system is 3m x 3m) are used in this design in order to leave enough working space (underneath and on the sidewalls) and to accommodate other mine services, such as, ventilation tubing, air and water pipes and cables. Systems analysis, engineering economics and computer simulation are used to evaluate the feasibility of the monorail mining system for decline development. Technical data relating to the operation of monorail systems in underground mining was obtained from Solutions for Mining Transport (SMT) – Scharf, of Germany, a company that manufactures monorail systems. Monorail haulage has definite advantages over conventional haulage; these include the use of electrical power instead of diesel, steeper gradients (up to 36[superscript]0), smaller excavations, tighter horizontal and vertical turning radii and potential for automation. The concepts are applied to a narrow vein ore deposit with results indicating that the monorail system delivers significant savings in terms of time and cost of decline development in this specific application.Stability of the monorail drilling system is critical in ensuring high performance of the drilling system. Stabilisation of the system requires determination of the horizontal, vertical and lateral forces of the system. According to the findings, these forces depend on the vector position of the two drilling booms that will be mounted onto the monorail train. Therefore, the research provides minimum and maximum monorail system reaction forces in horizontal and vertical stabilisers that will stabilise the system during drilling operations. Because of the configuration and positioning of the monorail drilling system, the research has also shown that with appropriate swing angles and lifting angles that will enable the system to reach the whole drill face during drilling operations.Since pneumatic or suction system is used during loading process, the research has revealed that the density of rock fragments, rock fragmentation, conveying air velocity and the negative pressure of the system would greatly influence the loading time and power consumption of the system. Therefore, the study has determined optimum fragmentation of the pneumatic system for various conveying air velocities. Additionally, for the efficient operations of the system, a range of conveying air velocities that give optimal mass flow rate (mass flow rate that give shorter loading time) and optimal power consumption have been determined at maximum negative pressure of 60kPa (0.6 bars).Since the monorail drilling and loading systems move on the rail/monorail installed in the roof of the decline and supported by roof bolts, suspension chains and steel supports, the strength of the support system is critical. To avoid system failure, it is imperative that the force in each roof bolt, suspension chain and steel support capable of suspending the weight of the heaviest component of the system is determined. Through the models developed, this study has determined the minimum required strength of roof bolts, suspension chains and steel supports that can suspend and support the components of the drilling and loading systems.To increase the efficiency and improve the safety of the two systems, the automation design for monorail drilling and loading systems’ processes have been developed. The proposed automation system would increase productivity by improving operator performance through control of the two systems’ processes. It is hoped that automation of the monorail drilling and loading systems will reduce the total drill-load-haul cycle time hence improving the efficiency of the systems.The application of simulation techniques was deemed useful to determine the performance of the monorail system in mining operations. During modelling, a simulation programme was written using General Purpose Simulation System (GPSS/H) software and results of the simulation study were viewed and examined in PROOF animation software. According to simulation results, the monorail system will have the same advance rate as conventional method since both systems have one blast per shift. However, the total drill-blast-load-haul cycle time for the monorail system is lower than for conventional method.Since the monorail system poses health and safety challenges during operations, through risk analysis, this study has identified root factors that have the potential to cause monorail system risk and hazard failure. The research has revealed that lack of maintenance of the monorail system and the monorail installations, production pressure and insufficient training of personnel on monorail system use are the major root factors that have the potential to cause risk and hazard failure. In order to improve the health and safety of the system, the study has suggested risk and hazard control strategies which are aimed at reducing the level of risk by directing corrective measures at potential root causes as opposed to addressing the immediate obvious symptoms such as monorail falling from support system, monorail running out of control, and others.A mine design case study using a monorail technology was conducted using one of ‘South Deeps’ gold deposits of Jundee mine operations (owned by Newmont Mining Corporations). Nexus deposit, one of ‘South Deeps’ deposits, was selected as case study area. The case study indicates that development of decline access to Nexus deposits using monorail technology is feasible. Compared with conventional decline development, results have shown that the monorail system has the potential of reducing the decline length to Nexus deposits by over 62.6% and decline costs by 63% (i.e., spiral decline and straight incline from the portal only). Furthermore, the study indicates that with the monorail system, there is a potential of reducing the total capital development costs to Nexus deposit by 22% (i.e., cost of developing the spiral decline, straight incline from the portal, crosscuts, ventilation network and installation and purchase of monorail train). Also, due to shorter decline length coupled with smaller decline openings, the duration of decline development reduces by 71.8%