No description available.

No description available.

In recent years, fierce competition, rising production costs and depressed prices for mineral products, have forced mining companies to find ways to improve efficiency and lower production costs. Given the fact that loading and hauling operations account for up to 60 % of the total costs in surface mining, the optimization and control of these operations can provide substantial reductions in the costs. Assignment of truck to shovels has been traditionally performed by fixed truck allocation and by truck dispatching. Several operations research and simulation techniques, which can be used to solve problems concerning surface mining operations, are discussed. The types of problems addressed are: how to allocate trucks to loading equipment, how to evaluate the performance of an existing operation, and how to predict the performance of a future system. For truck allocation, operations research methods such as: dynamic programming, integer programming, and heuristic algorithms are discussed. These methods are used mainly for decision making purposes. Queuing theory techniques, also analyzed, are used mainly for evaluation purposes. / Master of Science

Surface mining activities are known to affect the quantity and quality of stormwater runoff. This can create flooding and water quality degradation of receiving streams. The Surface Mining Control and Reclamation Act (SMCRA) of 1977 provides regulations intended to produce environmentally acceptable results from mining operations. The SMCRA requires that extensive pre-mining monitoring be carried out to assist in determining the probable hydrologic consequences (PHC) of mining. The Finite Element Storm Hydrograph Model (FESHM) was used to demonstrate the utility of hydrologic modeling concepts in simulating runoff volumes and peak flows. Guidelines were proposed for using this methodology to simulate selected pre-mining hydrologic conditions. The use of geographic information system (GIS) technology as a tool for improving data management and modeling efficiency was demonstrated. The required input watershed characteristics were digitized, stored, and manipulated using a computerized GIS. Appropriate software was developed to integrate the GIS with FESHM. The ability of FESHM to simulate runoff events in an ungaged context was evaluated using an experimental watershed. First, simulations were conducted using two separate data bases, "lumped" and "detailed", in order to evaluate the effect of limited data availability, as expected in mining regions, on FESHM's predictive ability. The "lumped" data base produced better simulation results, however, more thorough and detailed research is needed to determine the level of data resolution necessary for a given level of simulation accuracy. Next., significant runoff events from 17-years of the historical record were simulated using data from the "lumped" data base. Statistical analyses were used to make judgments on parameter estimation and model usage. Regression methodology was used to assess expected error and model bias. Simulation bias was found to be related to the input rainfall intensity levels. The results suggest that either spatial variability or parameter values were not adequately defined and that some form of calibration is needed. Two additional drainage basins were used to evaluate FESHM's predictive capabilities in situations considered representative of mining regions. The results indicated that more thorough investigations of watershed characteristics must be made, that calibration procedures should be performed for each watershed, and that FESHM does not adequately model the physical processes involved in forest hydrology. / Master of Science

The object of this thesis is to establish the necessary design criteria for a number of special feedback networks which were required to allow the final development of the Strip Mining Industry's first Automatic Crowd-Hoist Regulator. The introduction considers the purpose and needs for such a regulator by briefly outlining the present manual dipper loading operation. Section IV and Appendix 1 presents the analytical system requirements which are basically determined from an analysis of the system's inherent mechanical oscillatory frequency. Section VA is concerned with the development of the hoist and crowd motion transfer functions which are necessary to accomplish the stability analysis of the system. A general determinantal solution is obtained based on linear analysis to allow expression of the motion transfer functions as a factored polynomial. In section VB, the development of the necessary Crowd-Hoist feedback circuits is accomplished in terms of the system parameters defined from the analysis of the oscillatory mechanical system. Section VIA outlines the procedures to be followed in going from the basic mechanical system parameters to the specific control system hardware. The general requirements for a Bode analysis of the system GR is defined in section VIB, including the general procedures to follow in the utilization of the two lead compensation circuits provided. / M.S.

The implications of comminution practices on the planning of a typical open pit mine was investigated in this study by means of computer simulation. The objective was to assess the effects of mining costs as well as processing costs on the production plan of a typical open pit mine. For the purpose of the research, MineLib, an open library of ore body models was consulted. This led to the selection of a copper-gold ore body named “Newman1” for use in the strategic mine optimisation. Various scenarios were considered in order to highlight the contribution of comminution costs to the mine plan. In all the simulated scenarios, the objective function was to maximise the Net Present Value (NPV). And in terms of simulation setup, the comminution costs and cut-off grades were systematically varied from 70 % to 140 %. It was hence possible to investigate their effects on the NPV of the Newman1 ore body using SimSched, a freeware for mine optimisation and planning. Results showed that there is a great opportunity to increase the NPV of the Newman1 block model by adjusting the contribution of processing costs in general and comminution costs in particular. This can be achieved for instance by controlling the policy of cut-off grades, lowering production costs, and increasing throughput. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

In the increasingly competitive coal market, it is becoming more important for coal operators to develop mathematical models for surface mining which can estimate mining costs before the actual mining begins. The problem becomes even more acute with the new reclamation laws, as they affect surface coal mining methods, productivity, and costs. This study presents a computer simulator for a mountaintop removal type of surface mining operation. It will permit users to compare the costs associated with different overburden handling and reclamation plans. It may be used to minimize productivity losses, and, perhaps, to increase productivity and consequently to reduce operating costs through design and implementation of modified mountain top removal methods. / M.S.

Typescript (photocopy). / Digitized by Kansas State University Libraries

Thesis (MScIngwet)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The diesel consumption of haul trucks deployed on opencast mines was investigated as a means of reducing the Total Cost of Ownership (TCO) of mining haul trucks. The conceptualisation of TCO and an introduction to the mining operation was presented as an introduction to the field of research. Thereafter, a review of the available literature revealed that linear programming, queueing theory and coast-down testing were applicable means of investigation. The relevant engineering sciences were applied and correlated with experimental and measured data from the Grootegeluk, Sishen and Thabazimbi mines operated by Kumba Resources Ltd (formerly known as ISCOR Mining). A cost-driver model for diesel consumption was formulated by exploiting the expert judgement of role players in the mining operation. A cost-driver model was developed for the Sishen, Thabazimbi and Grootegeluk mines. The cost-driver models were then modelled as a linear programming problem and solved using the student version of LINDO Optimization Software. The results were discussed and a universal diesel cost driver model was formulated by consolidating the individual diesel cost driver models. The operational cycle of haul trucks was simulated in order to quantify equipment utilisation and reduce diesel consumption of the mining vehicles. The operational cycle of haul trucks was modelled utilising queueing theory. The simulation of the queue network was implemented in Matlab using the next event advance method and was called Q Sim. Q Sim - - was utilised to investigate optimal fleet size and the economies of scale of haul truck capacity. The results of coast down tests were analysed in order to determine the effect of treating mining roads, with a bitumen product, on rolling resistance coefficient. Finally, recommendations for further research are proposed. This includes further refinement of the diesel cost-driver model, expanding the scope of application of Q_Sim in the mining operation and further investigation of dust reduction by bitumen products. / AFRIKAANSE OPSOMMING: Ondersoek is ingestel na die dieselverbruik van myntrokke sodoende die Totale Koste van Eienaarskap (TKE) van myntrokke te verminder. Die konsep rondom TKE is bespreek en 'n inleiding tot die mynybedryf is aangebied sodoende die verskeie aspekte in verb and te bring. 'n Literatuur studie het gevolg, wat aangetoon het dat lineere programmeering, toustaan-en loswieltoetse toepaslike navorsingsmetodes is om die nodige resultate te verkry. Daarna is hierdie ingenieurswetenskappe toegepas en 'n vergelyking is tussen die eksperimentele en gemete data van die Grootegeluk, Sishen en Thabazimbi myne getref. 'n Diesel koste-drywer model is opgestel met die insette van kundige rolspelers in die mynbou bedryf. Dit het gelei tot Koste-drywer modelle vir die Sishen, Thabazimbi en Grootegeluk myne. Die modelle is met lineere programmeering as probleemstelling daargestel en is deur middel van die studente weergawe van die LINDO optimaliseringssagteware opgelos. Die resultate was toe bespreek en daarvolgens is 'n universele diesel koste-drywer model opgestel deur die reeds-geskepte modelle te konsolideer. Die operasionele siklus van myntrokke was gesimuleer sodoende die benutting van toerusting te kwantifiseer en die dieselverbruik van myntrokke te verminder. Hierdie operasionele siklus was gemodelleer deur middel van die toustaan-teorie. Die simulasie van 'n toustaannetwerk was in Matlab gevoer deur Q_Sim te gebruik. Hierdie metode was gebruik om die optimale vloot grootte en die invloed van myntrokkapasiteit te ondersoek. Die ontleding van die loswieltoetse was gedoen om die invloed van In bitumen prod uk op rolweerstand te bepaal. Ten slotte is aanbevelings vir toekomstige navorsing bespreek. Dit behels die verder aansuiwerings van die diesel koste-drywer model, die uitbreiding van aanwending van die Q_Sim in die mynbou en 'n verdere ondersoek om stofvoorkoming in die mynbou te bewerkstellig deur die gebruikmaking van bitumen produkte.

Thesis (MEng) -- Stellenbosch University, 2000. / ENGLISH ABSTRACT: The utilisation ofDraglines to remove overburden in surface mining operations is often the process that determines the output of these operations. The bucket and its rigging have been identified as important components where design changes can improve the efficiency of the dragline. It is necessary to create a method to predict the dynamic behaviour of the bucket when various design changes are made to the rigging and the bucket. A rigid multibody dynamic method is formulated that can be used to predict the behaviour of any physical system that can be modelled as a set of connected rigid bodies. This multibody method is verified with analytic test problems and an experiment. A description is given how to use this rigid multibody dynamic method to model the dragline and predict the behaviour ofthe bucket during an operational cycle. / AFRIKAANSE OPSOMMING: Sleepgrawe word gebruik in oppervlakmynbouaktiwiteite om die mineraal neerslae wat ontgin word te ontbloot. Hierdie proses bepaal baie keer die produksie van die mynbou aktiwiteit. Die sleepgraaf se bak en die takelwerk van die bak het 'n groot invloed op die sleepgraaf se werksverrigting. Om die bak se werksverrigting te verbeter is 'n metode nodig om die dinamiese gedrag van die bak te voorspel. In hierdie dokument word 'n metode beskryf waarmee die dinamiese gedrag van enige stelsel bepaal kan word, wat as 'n stelsel van onderling-verbinde onbuigbare liggame beskryf kan word. Die korrektheid van hierdie metode is getoets met behulp van analitiese sowel as eksperimentele metodes. Daar word ook 'n beskrywing gegee hoe hierdie metode gebruik kan word om die beweging van die bak tydens 'n tipiese werksiklus te voorspel.