Use of genetic algorithms in a mining problem

ABSTRACT

This paper introduces the principles of genetic algorithms and presents their properties and structure. The application of genetic algorithms in the mining problem of ore grade estimation is discussed and the results are compared with previously published data. The outcome of this paper indicates the potential of genetic algorithms in mining applications.     

A review of spontaneous combustion studies – South African context

Abstract

One of the challenges in the coal mining industry is self-heating of coal as this can become a problem during mining operations, stockpiling and transportation. This study reviews the mechanism of self-heating, areas of spontaneous combustion, various factors influencing self-heating and different experimental studies to predict its occurrence. The technical control measures applied to minimise self-heating with special consideration to South African coals are also discussed. The distribution and association of unknown materials accelerating spontaneous combustion at different bands within the seam is yet to be studied. A site evaluation of the effects of these parameters is underway.     

Practical considerations for developing an automatically driven open pit mining machine: Compact bucketwheel excavator

ABSTRACT

The arc of electronic revolution is here bringing changes to mining technology. The surface mining Industry is keen to be part of this changing environment. Efforts are being directed towards developing automated mining equipment. This paper, using the compact bucket wheel excavator as an example examines the theoretical and practical parameters which must be considered in developing an automated machine.     

Computer applications in mine maintenance

ABSTRACT

This is an overview of the application of digital computers to the Maintenance Planning function and to the Maintenance Engineering support role of a large open pit BWE/conveyor mining operation. The benefits to Suncor Mine Maintenance are highlighted so this paper will be of interest to any group contemplating the installation of computers to improve productivity and flexibility.     

Fuzzy multiple-criteria decision-making: Application to AML project selection

ABSTRACT

In this paper, we present the application of fuzzy multiple-criteria decision-making to the problem of abandoned mine land (AML) project selection. More specifically, the category of multiple-criteria techniques known as fuzzy ranking methods are used to rank projects under conditions where the criteria of selection are imprecisely defined and the project scores for the criteria are subjectively determined.

An experiment was designed in which 14 experts contributed their knowledge of AML project criteria to the fuzzy ranking methods through three questionnaires. The first two questionnaires provided the essential information for the methods to form a fuzzy mathematical ranking relationship. The third questionnaire then provided the experts' scores for each of the chosen criteria for eleven candidate reclamation projects chosen from Pennsylvania's AML project inventory. In addition, the third questionnaire also sought overall project rankings from the experts to compare with the rankings provided by the fuzzy ranking methods.

The results appear to prove that fuzzy rankings methods can satisfactorily rank projects of this type and will generally produce results similar to that produced by the experts. While not necessarily better than human rankings, the rankings of the mathematical methods may increase the objectivity in decision-making even though bias in the original data cannot be eliminated.     

A pick force calculation method suggested for tool lacing of mechanical excavators employing drag tools

Abstract

This paper deals with tool lacing design of partial-face cutting machines employed for mechanical excavations of rocks, coal and stones. A rational comparison between relief cutting and groove deepening was made by simulating actual cutting actions of picks under the same conditions at different spacing to depth ratios, respectively, through full-scale laboratory linear cutting experiments with radial and point attack tools. It was found that the top portion of a groove with approximately polygonal-shaped cross section has no significant effect on the magnitude of tool forces. The effective cutting was understood to take place mainly in the lower portion of this cross section, termed ‘effective area’, which is encompassed by a triangle with an apex angle twice the breakout angle of unrelieved groove. This finding has led to the introduction of a pick force calculation method for computer assessment of tool lacing for rock, coal and stone cutting machines. The ‘effective area’ of cross sections which were calculated by this method, was found to be in good correlation with corresponding measured tool forces. The method is simple and free from assumptions which have to be specified for various pick cutting position. It was also verified by the results of some experimental data of previous investigations.     

An analysis of progressive slope failures in brittle rocks

ABSTRACT

Current methods for analysis of slope stability, such as Bishop method, Janbu method and Samar method, are based on limiting equilibrium theory. The limiting equilibrium theory does not adequately explain failures in brittle rock slopes. This paper presents some results from numerical simulation using Boundary Element Method of failure process in Brittle Rock slopes. The simulation is based on the energy release concept as well as Mohr criterion of failure and provides an analysis of progressive slope failure in brittle rocks.     

Recent findings in open pit optimization

ABSTRACT

This paper reports on research in which pit designs using the Lerchs-Grossman and Moving Cone Algorithms were individually compared with those of the Dynamic Cone Algorithm. The comparisons wore on the basis of total final pit economic values. Details of the study are described and the results obtained discussed. The results showed that each algorithm in the pairs tested, gave several higher final pit economic values than the other. It is concluded that a correct approach to open pit optimization is to use several different algorithms and then select the beat valued pit from among the resulting designs.     

An application of queuing analysis to the production of aggregates in quarry operations

ABSTRACT

High incidence of failure of quarry operations has been the trend in Nigeria's crushed stone industry for some time now. The problem which emanates from poor planning, design and management cuts across all feizes of operations. Generally, productivity is often maintained at uneconomic levels at the expense of much needed revenue. Uncontrolled production of aggregates often results in the over production of minimally demanded sizes while those that can generate more revenue to keep the industry afloat are in short Supply. As a solution to the above problem, this paper presents the technique of linear programming as an analytical tool for controlling the production of different aggregate sizes with a view to maximizing profit. Specifically, the paper describes the problem formulation technique and discusses the optimum solution obtained from the Application of the resulting model to the problem of an existing quarry.     

Modelling,analysis and preliminary studies for automatic scooping/loading in a mechanical loader

ABSTRACT

A fundamental step of process analysis and modelling for the scooping and loading function of a loader type excavating machine is carried out. This is a part of the essential work towards automation of such a machine. Emphasis is given here to Load-Haul-Dump mining machines, frequently used in underground mining operations. However, for many other applications, such as remote excavating and contaminated soil removing with a loader type excavator, the same theory applies and the same sort of experimental work becomes necessary. In this work the loading gear is first modelled as a mechanical manipulator, then the nature of the involved resisting forces, that also depend on the properties of the material to be loaded, and the fact that some knowledge about these stochastic forces is required, is pointed out. The paper, moreover, presents a discussion about the more appropriate trajectory of motion of the loader bucket.     

Development of an air attenuation model for noise prediction in surface mines and quarries

ABSTRACT

Surface mining and quarrying produces a complex noise field. The noise generated by mining operations changes with time and is affected by the changing meteorological conditions in situ. Theoretical research on the attenuation of noise in air has formed the basis for the development of an air attenuation model. The methodology developed by the authors accounts for the prevailing temperature and relative humidity conditions in the area. The model also includes the evaluation of ray path curvature directly from long-term experimental wind velocity and temperature data, or indirectly in terms of the Net Solar Index and the wind velocity. This paper describes the air attenuation model, which was developed as an integral part of an environmental noise prediction system.     

Expert systems as decision aid in surface mine equipment selection

ABSTRACT

Mining integrates the skill of many engineering disciplines. Within these disciplines lies experience and expertise found in not other industry. To capture and widely apply this expertise is the challenge to developing the knowledge base expert systems

The characteristics of plausible reasoning shared by medical diagnosis and mineral exploration are common, to some degree to many other evaluation tasks as well. Hence, the purpose of this paper is to illustrate, by a cast study of mining equipment selection, the general process of capturing and encoding human expertise into a mechanical realization.     

Optimum curvature in pit slope design

ABSTRACT

In surface mining the curvature of the pit slope is an important parameter in its safe and economic design. Research has shown that concave slope faces are more stable than planar or convex ones.

The object of this paper is to demomstrate the effect of concavity on the optimum curvature, for the two slope angles commonly practiced in surface mines, 60° and 65°. The Finite Element Method (FEM) was used to simulate the variable mining conditions and the changing material properties. The analysis has been limited to stress analysis and the corresponding factor of safety to arrive at an optimum slope curvature.     

Design,construction and maintenance of surface mine haulage roads

ABSTRACT

Often laborious evaluations are carried out to select mining equipment with little attention being paid to the design, construction and maintenance of the surface on which this equipment must travel. This paper deals with the many facets of designing surface mine haulage roads identifying elements which are critical to realizing the full potential and productivity of the equipment

More specifically, the influence of grade and rolling resistances on truck productivity has been emphasized. Procedures for properly constructing and maintaining haulage roads have been summarized.     

Analysis of the strata buckling mechanism at the Grand-Baume coal mine,France

ABSTRACT

This paper describes a three hinge strata buckling mechanism and its influence on the west wall of the Grand-Baume open pit coal mine. The analysis is extended to investigate the stability at the projected maximum depth of the pit In order to study and quantify the failure mechanism, two analysis methods were employed. The first method used the base friction table on which scale models of the slope were represented. The second method made use of the mathematical modelling of the slope stability by means of a limit equilibrium computer program, specific to three hinge strata buckling. Details on the application and the results of the two methods are presented. These are henceforth compared with the field observations at the Grand-Baume mine.     

An application of goal programming to production planning in the crushed stone industry

ABSTRACT

The problems facing the aggragate stone industry in Zambia such as low capacity utilization, failure to meet customer requirements, unnecessarily high operating costs, poor inventory control practices, heavy borrowing and overall poor economic performance are as a result of subjective decision-making related to production planning. This is also true of the industry in nearly all member countries of the SADDC(Southern African Development Co-ordinating Conference) where quarry closures are not uncommon.

As a solution to the problem of production planning and control in the crushed stone industry, this paper presents results of an application of the goal programming technique to a Zambian case study engaged in the production of limestone powder for the chemical industry. The formulation of a mathematical model for handling multiple objectives is discussed. The goal programming model can be used by management as a strategic decision support instrument.

Results of the study show that over time work is related to the levels of demand for each product as well as the capacity utilization of the plant. The conflicts among the various goals of the short term production plan are identified. The study suggests that goal programming can provide an improved model to solve the problem of production planning in the crushed stone industry.     

A study of the practicality of cavitating water jets

ABSTRACT

Although the potential of cavitating water jets for augmenting the fragmentation (or other applications, such as cleaning) ability of continuous water jets has been known for a nutfiber of years, their use is not as widespread as anticipated. Good performance of cavitating water jets has mainly been documented under submerged conditions, where its usefulness is limited, for a given set of operating conditions, to very short standoff distances. In this paper, sample results of flow visualization, erosion of aluminum and cutting or fragmentation of rock samples are presented in an attempt to elucidate the influence of geometrical and operating parameters on the performance of cavitating water jets. Possible advantages of artificial submergence through special nozzle design or an external water shroud are also examined. The ultimate goal of this study is to establish the usefulness and limitations of cavitating water jets for fragmentation or fracture of hard brittle materials such as socks and concrete and other applications.     

Economic feasibility of introducing trolly assisted haulage to an Australian open pit mine

ABSTRACT

The paper presents results of the study which evaluated feasibility of introducing a trolley assisted haulage system to an Australian open pit mine. The study compared expected performance of the trolley system, an updated version of the systems used in several South African mines, to that of the fleet of mechanical drive trucks used by the mine at present leading to definition of site specific conditions under which the trolley system may become economically feasible.     

Monitoring networks for open pit mines

ABSTRACT

Monitoring networks are used in open pit mines to ensure safety of men and equipment and avoid disruptions in the mining operation. The methodology applied to monitoring networks includes their design, selection of suitable instrumentation, control of systematic errors, and analysis of the observational data. In this paper it is proposed that the methodology suggested in Larocque (1977) be modified to give a more reliable determination of movement. A BASIC computer program suitable for a hand held computer, which enables one to detect statistically significant horizontal movement in the field, is also given.     

Design of anchoring in rock with planar failure

ABSTRACT

This paper reports on an analytical approach to the determination of a minimum safety factor for rock slopes subject to planar failure, prior to reinforcement. The safety factor determined by this approach may then be used in the design of active and passive anchor systems for slope support under static and dynamic conditions. It may a1so be utilized to eva1uate the anchor force and inc1ination for optimum rock reinforcement

Practical design examples are given by taking into account parameters such as: groundwater pressure, surcharge, seismicity, anchor dimensions and passive and active forces.