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By Margaret Armstrong, Arne Berckmans

The longterm aim of this research project is to find fast ways of simulating the recoverable reserves of a deposit for input into financial Monte Carlo simulations without having to conditionally simulate the whole orebody many times. The first step in this re- search is to visualize and quantify the ore tonnage T and the metal quantity Q above an arbitrary cutoff z. This paper presents detailed results for one specific distribution, the lognormal. These lead to a suggestion of a fast way of simulating QTz curves.

Jan 1, 1996

By Nathaniel White, Todd Kilduff, Justin Laviolette, Dan Laviolette, Randy Zeigler, Sean Sundermann

The Mitchell Point tunnel is a part of several ongoing efforts to connect the 12-mile-long Historic Columbia River trail between Mitchell Point Outlook to Mitchell Point Drive. The tunnel lies inside the Mitchell Spur entablature basalt geologic feature, extending 647 linear feet utilizing a typical horseshoe section with a height of 14.5 feet. The Oregon Department of Transportation (ODOT) required proper vibration control to minimize potential impacts to Interstate 84 and Union Pacific rail immediately below the tunnel excavations and sensitive, rare plants. The method of designing the vibration monitoring program and the results of its implementation show the iterative process of using monitoring to improve blast design as excavation proceeds, such as reducing air overpressure and COVID-related supply chain-constraints.

Dec 1, 2022

By M. E. Breitrick

Newmont Gold operates the Carlin East underground, one of four underground gold mines the company operates in northeastern Nevada. Carlin East began full production in early 1995. The mine's current rate is 900 t/d (1,000 stpd), producing about 4.6 t/a (150,000 oz/year). About 125 hourly and salaried personnel are employed at the project for its estimated six-year mine life. Two mining methods are currently used at the Carlin East Mine. Longhole stoping with cemented backfill accounts for 70% of the total mine production. Conventional underhand drift and cemented fill accounts for the balance of the daily tonnage. In December 1996. Newmont purchased an AC-Eickhoff ET-210 roadheader. The machine went into service in mid-June 1997. It is used in longhole Stope topcut development and cut-and-fill production at a rate of 225 t/d (250 stpd)

Jan 1, 1998

By C. N. Greene

I am sure it is obvious to all of you that a complete program of casualty and property insurance is as necessary for any tunneling contractor as it is for anyone else involved in trade in the United States today. Going beyond those general undefined terms, there are many areas that need specific attention, particularly for contractors, regardless of size. WORKERS' COMPENSATION Workers' Compensation is mandatory in all states and the District of Columbia. In most of the states, private insurance provides this coverage. In a few states, the state operates Workers' Compensation funds, some of which are competitive with the private sector and others are operated on a monopolistic basis. Under a monopolistic setup, you have no choice, you must buy coverage from the state. Self insurance of the Workers' Compensation risk is also an alternative in most jurisdictions. With a contractor operating only in the U.S., the coverage extensions are few in number. If your work brings you anywhere near navigable waterways or land extensions thereof, you should have both U. S. Longshoreman and Harborworkers' coverage, as well as Employer's Liability coverage for the master or members of the crew of a vessel.

Jan 1, 1983

By Koehler Stout, Leroy Friel

INTRODUCTION Hydraulic sand fills have been extensively used in the United States in deep metal mines since 1940, and hydraulic fills have been placed in coal mines in Europe for many years. Numerous surface hydraulic fills exist in Appalachia for the disposal of coal mine waste and throughout the United States for the disposal of other mining, manufacturing, city, and paper company wastes. Hydraulic fills, as they are now deposited in stopes in mines, are often deposited at near minimum density and hence provide very little support to stope walls and pillars. If the support strength of fills could be increased, perhaps ground conditions in deep mines could be improved making them safer and more efficient. Surface fills deposited at higher densities could be covered with top soil upon which grass could be planted. The purpose of this paper is to describe procedures where the support strength of hydraulic fills can be considerably increased, and the focus of the paper is on applications to deep mines. In deep mines the objective of increased fill strength is to reduce heavy ground problems, improve destressing techniques, reduce or eliminate rock burst incidences, provide better working conditions, provide wall support so that more or all ore pillars can be removed, and improve mine safety, efficiency, and reduce surface environmental problems. The authors have shown that it is possible to improve fill strength used in deep mines. This paper reports the slurry filling procedure, fill testing techniques, and some recommendations for application in deep mines. Some of the reasons for low strength hydraulic fills are:

Jan 1, 1979

By Wayne Stange

Due to the availability of user-friendly microcomputer based packages, the use of simulation is increasing.. Users have however encountered problems inherent to the structure of sequential-modular simulators. These are the difficulties associated with estimating parameters for arbitrary' models and the solution of design and optimization problems. The implementation of an optimization routine in the simulator MicroSim has facilitated the solution of such problems. The literature indicates that more efficient numerical techniques for solving optimization problems than those presently used in MicroSim are available. These techniques, together with user-interfaces which allow such problems to be specified easily by users, will result in the development of simulators much more powerful than existing ones.

Jan 1, 1989

By Stanislaw Wasilewski, Zdzislaw Krzystanek, Boleslaw Firganek

The experimental system for mine venti1ation control in Staszic colliery has two - level structure. In the lower - measuring 1evel the existing computer - based early fire detection system has been used completed with a number of additional sensors needed for ventilation parameters monitoring. The higher 1evel is a secondary computer equipped with a suitab1e dedicated software performing data processing according to the control a1gorithm. Direct control of air flow in a selected mine district is performed by means of a remotely controlled automatic regulator. Apart from functional tests of the system and its elements some research work has been carrying out in the colliery based on observations of transient effects caused by changes in air flow distribution.

Jan 1, 1989

By E. Pardo-Igúzquiza

Most mining applications of geostatistical simulation are to the simulation of quantitative variables, such as grade. In many instances the occurrence of quantitative variables and the values they take are controlled, at least partially, by qualitative, or categorical, variables. Examples include quartz-vein controlled gold orebodies and stratigraphic silver/lead/zinc deposits. In these cases a realistic simulation must include geological controls on the spatial distribution of the simulated quantitative variables. This paper describes extensions to, and algorithms for, the truncated plurigausian method of simulating categorical variables. The categorical variables are modelled as indicator random functions that represent the presence/absence of the variable at spatial locations. Stochastic images of the distributions are obtained by truncation of realisations of two Gaussian random functions simulated at the same locations. Parameters required are the thresholds for truncation of the Gaussian variables and the covariance structure of each Gaussian random function. These parameters are estimated from the experimental proportions of each variable and indicator direct and cross semi-variograms. A detailed case study is shown in order to illustrate the procedure, to discuss the results and to present the algorithms for plurigaussian simulation.

Jan 1, 2002

By A. L. Mular

Steady-state material balances calculated from data measured at various locations around process units are useful for many purposes, such as metallurgical accounting, on-line control, and the development of mathematical models. Often it is possible to calculate material balances by several independent procedures when excess measurement information, i.e., redundant data, is available. Clearly, if the data were collected without measurement errors, a theoretical condition never found in practice, all material balances calculated from redundant data would be in agreement. The real situation is that error exists in practical measurements, so that the results of material balances determined from available optional procedures differ. Consequently, best fit computational procedures to improve the material balances by taking measurement errors into account have been formulated. Such procedures can be used also to judge whether measurements are grossly in error due to either faulty observations or defective data sensing devices. A variety of mathematical techniques are available which serve to adjust raw data. The adjusted data permit mass balancing that does not depend on the computational method. To illustrate the need for an adjustment procedure, Table 1 shows a raw data set acquired around the Brenda Mines Ltd. No. 4 grinding circuit shown schematically in Fig. 1. At least seven optional ways to calculate a circulating load ratio may be employed. These are shown in Table 2 where, depending upon the calculation [ ]

Jan 1, 1979

By J. E. Lawver, F. S. Knoll

Introduction Electrostatic separation is the selective sorting of solid species by means of utilizing forces acting on charged or polarized bodies under the influence of an electric field. Electrostatic separation is effected by adjusting those forces acting on particles due to the electric field as well as co-acting forces such as gravity or centrifugal forces so that the different species will have different trajectories at some predetermined time. Electrostatic separations can be broadly defined as being either electrophoretic or dielectrophoretic. Electrophoresis is the separation of charged particles in an electric field, whereas dielectrophoresis is the separation of neutral particles in an electric field1. Examples of an electrophoretic separation can be found with sepa¬rations that use corona charging (ion bombardment), contact charging (triboelectric) and conductive induction. Dielectrophoresis motions are due to the stress and repositioning of charges, i.e. polarization of a neutral particle when exposed to a non-uniform electric field. Separations made using corona discharge devices are often called high-tension, electrodynamic or ion bombardment separations. These are the most prevalent in use today in mineral processing. Dielectrophoretic separation of most minerals is based on differences in dielectric constants of the solid species and usually requires the use of expensive intermediate dielectric fluids. Dielectrophoresis has not been employed for industrial mineral separations, though its effects pose interesting possibilities1, and pilot-plant units developed by the U.S.B.M. are available for testing2. Our discussion will be limited to the three forms of electrophoresis found in commercial practice. Typical Industrial Separations Typical industrial applications of electrostatic separation are: 1. Dry concentration of heavy minerals: ilmenite, rutile, zircon, monazite, xenotime, columbite-tantalite, cassiterite, hematite, scheelite and others. 2. Separation of salts: halite-sylvite, etc. 3. Purifications of foodstuffs such as the removal of impurities and

Jan 1, 1986

By R. S. Mateer

Linear programming on desktop computers is commonly used to optimize coal blending proportions. The objective function is usually the cost of the blend. The constraints consist of materials and heat balances as expressed as linear functions of the blend. This is illustrated in Example 1. Inclusion of a sulfur compliance constraint in more complex because the maximum permitted sulfur percentage is not a pre-specified constant. Rather, it is a function of the calorific power of the blend itself. The current limit of 1.2 pounds of sulfur dioxide per million Btu may be expressed as: [Sulfur Max%= 0.6 . Hl10,OOO with H in Btu/lb.] A proper constraint equation may be formed by defining for each coal a function that is the difference between the actual sulfur percentage and the maximum sulfur percentage. This may be regarded us an excess sulfur percentage. For Coal A of Example 1. this would be: [ Sulfur Excess%=0.5-0.6 13,000/10,000=-0.28] This value would be used as the coefficient of the weight proportions of this coal in the blend. The complete constraint equation would then be the sum of such terms for each coal set less than or equal to zero. This is illustrated in Example II. [ ]

Jan 1, 1995

By R. C. Fox

The geophysical aspect of reconnaissance marks the beginning of extensive computer applications supporting development of a mine. Although there are some storage and retrieval applications in geology, and some statistical analysis in geochemistry, large-scale compilation, reduction, and interpretation of mineral resource data are initiated in reconnaissance geophysics. The reasons for this fact are quite simple. Geophysics is oriented toward quantitative evaluation of areas of interest, and methods of data collection are automated to the extent that large amounts of analog and digital information are recorded. The large volume of data must be interpreted in a reasonable time. Furthermore, some modeling problems involving complex numerical solutions could not be attempted without the computer. Therefore, the computer is essential to the success of an exploration project using geophysics. For example, aeromagnetics is a common technique for reconnaissance examination of areas associated with sulfide systems and porphyry deposits. An area covering 161 X 161 km (100 X 100 miles) may be flown with a 1.6-km (1-mile) line spacing yielding 10,000 line miles (16,093 km) of data. If only 10 measurements are recorded per mile, 100,000 data points, including location and magnetic field intensity, must be reduced and stored for quantitative interpretation. Computer applications often represent a significant investment in manpower and hardware. It is desirable, therefore, to initiate an engineering approach to the application of computers to geophysics. By this it is meant that computer programs and systems should be formulated, developed, and implemented in a disciplined manner such that their usage is dependent only on the application and not on the individual doing the programming. In other words, computer application, development, and usage should evolve beyond the personal gadget phase to an important applied technology. Geophysics has evolved over the past two decades in a course parallel to computer hardware development. During the sixties, the computer became large enough and fast enough that complex models required by geophysics could be solved. Automation also relieved the geophysicist from routine manual calculations. During the seventies, computing power in¬creased and applications expanded from two-dimensional problems to three-dimensional modeling. Moving into the eighties, as computer hardware costs will significantly decrease, the major expense of computing will be the manpower required to develop, implement, and use an application; therefore, improved programming techniques and applications software engineering methods will be used to optimize and preserve this investment. This chapter presents a general overview of computer methods in geophysical reconnaissance; it is divided into two parts: geophysical methodology and software engineering.

Jan 1, 1979

By Michael J. Martinson

Mine ventilation has been evolving as a separate field of study since the middle of the nineteenth century, and some practitioners might assert that mine ventilation has come of age as a discrete field in the last decade or two. Certainly the extensive literature now available on many facets of the subject, international congresses, the phenomenal upsurge of interest in mine ventilation in the United States of America since the passage of the 1969 Federal Coal Mine Health and Safety Act, and the existence of a virile mine ventilation society in South Africa with its own monthly journal all point in this general direction; on the other hand the lack of a rational design philosophy for ventilating mines suggests that mine ventilation may still be on the threshold of maturity. To generalise, many mines are still ventilated simply to comply with arbitrary statutory regulations, or with some ill- defined notion of reducing the risk of injury associated with the atmospheric environment in mines. Hazards in this category include oxygen deficiency, toxic gases and particulates, pathogenic gases and aerosols, explosive gases and dusts, and extreme climatic conditions. Although many mines are ventilated to abate the risk of a specific injury, there is inevitably a spectrum of latent and patent atmospheric hazards in every underground mine. The writer (Martinson, 1976) has previously drawn attention to the dearth of material on mine ventilation design in textbooks and technical journals, and to the overly simplistic approach sometimes adopted in the limited work published on the subject. The available material undoubtedly contains useful technical data and persuasive views, but seemingly could not be used to demonstrate the rational engineering approach to mine ventilation design advocated in the present paper. The range of papers presented at the 1975 and 1979 Congresses, and the diverse interests and affiliations of delegates, emphasize the multidisciplinary nature of mine ventilation. Easily recognisable topics include: Fluid mechanics Thermodynamics Heat transfer Flames and combustion Aerosol physics Radiation physics Geophysics and geomechanics Occupational diseases Epidemiology Industrial physiology Despite these heterogeneous connections there can be little doubt that mine ventilation is fundamentally an engineering field and not an off-shoot of some other branch of applied science. The distinction is important because mine ventilation has essentially developed as a form of ad hoc trouble- shooting, and in the process mining engineers have relied extensively on the assistance of experts drawn from other fields. Thus historically there has been limited scope for the application of rational design techniques, and personnel enlisted from scientific disciplines may not have had any previous experience in the intricacies of engineering design.

Jan 1, 1980

By J. A. Herbst, K. N. Han, P. B. Queneau, S. W. Asihene

As hydrometallurgy matures as a technology, more of its existing process knowledge will continue to be summarized in the form of detailed mathematical models. This development is happening at a time when major improvements in computer hardware have reduced the cost of computing. The opportunity then exists, through the solution of these process models, to design, control, and optimize hydrometallurgical plants on the basis of the physics and chemistry of its processes and less on empiricism. In this paper, a review of the current capabilities of sensors and phenomenological models for selected hydrometallurgical processes is presented. Future trends, in terms of the control and optimization of hydrometallurgical plants, are then explored. The possibility of simultaneously optimizing plant design and associated process control system performance is discussed.

Jan 1, 1993

By W. M. Jr. Aubrey, R. L. Stone

INTRODUCTION Most metallic minerals and some industrial minerals have a relatively high specific gravity and most have at one time or another been concentrated by gravity methods. The principles of gravity concentration are straightforward, well documented and easy to understand, but in practice there are many pitfalls that await the engineer in the development of an integrated flowsheet. Gravity concentration equipment has a long history of use and there is a great diversity available. The equipment is capable of treating material over a broad size range, only falling off in efficiency in the very fine sizes. Gravity concentration is also inexpensive, generally free of environmental problems, and commercial equipment can process large tonnages of ore with a minimum of capital cost. As might be expected of an efficient and low cost process, the bulk of the tonnage quickly and inexpensively. Another obvious application is treating mineral deposits such as hematite and manganese ores that are sufficiently liberated after a minimum of crushing to allow production of a coarse concentrate that will meet market specifications. Except for hand picking and mechanical sorting, there is no competing process on coarse size material. Conversely, it is sometimes obvious that gravity concentration does not warrant consideration. Examples are ores that require very fine grinding to attain liberation, for ores where the minerals of interest have a gravity similar to the gangue, and ores that are strongly magnetic. Actually a mineral processing engineer may not know if gravity is the best way to concentrate an ore, but he should have little difficulty recognizing when gravity concentration deserves consideration based upon specific gravity differences and liberation gravity concentration has wide use. size. His challenge then is to At times its selection as the identify and test the applicable primary concentration process is processes, to develop a obvious. Low grade placer deposits metallurgical balance and flowsheet of tin, gold and beach sands usually for the best process, to estimate are only profitable because gravity production rate over the life of concentration is able to throw away the deposit and to make equipment

Jan 1, 1986

By S. W. Kan, M. G. Kakarkis, J. Zelanco

Grouting has been used in underground mining for more than 20 years. Chemical grouting is often used as a remedial measure when the implemented ground-control program is unable to completely prevent structural failures or when there is a need for preventing a structural member from unraveling. The utilization of polyurethane grout is restricted by its limited range of physical and mechanical properties. To overcome some of the drawbacks of polyurethane, research is being conducted on a newly developed polyester based grout. The polyester resin, identified by Sandvik as Strata Grip, provides a number of features, including variable gel times and a much-reduced chemical hazard. Equally important are the mechanical properties of the product. The strength and deformability of any chemical grout must be compatible with the intended purpose of grouting and the expected deformation of the rock that is to be grouted The assessment of the mechanical properties of polyester grout is the focus of this work. Field experiences and laboratory research defined the properties of an effective grouting material. Experimental results indicate that the polyester grout meets or exceeds the recommended properties for many injection applications. Furthermore, the results suggest that the ability to adjust mechanical properties via resin formulation has the potential to expand the applicability of chemical grouting in ground control.

Jan 1, 1999

By P. C. Thakur

Mine productivity, measured by the output of minerals per manshift, depends on a number of factors including physical conditions of the minable seam, type of mining equipment, management techniques, worker attitudes and governing jaws and regulations. The greatest scope of improving productivity lies, perhaps, in modifying physical conditions to an advantage and using highly productive equipment. In the case of coal mines, increased productivity can be achieved by (i) obtaining prior knowledge of the mineable property, e.g., the grade and thickness of, the coal seam, presence of sand channels, faults, etc., (ii) eliminating conditions that hamper production, e.g., high emissions of methane and water, and (iii) using more productive mining techniques. Conoco/Consol's (Conoco Inc. and Consolidation! bal Company, a fully-owned subsidiary) horizontal drilling system was developed with the hove objectives in mind. It can drill 75 to 1001 in diameter boreholes to depths of more than 600 1 and maintain the borehole in a preselected horizon. Such boreholes can be utilized for premining exploration of the coal seam, for removing methane and water and in devising mining techniques with high productivity. The purpose of this paper is to describe the horizontal drilling system briefly and to discuss its applications in the above-mentioned- areas.

Jan 1, 1980

By Rob Dorey

The disposal of mine waste continues to be one of the main controlling factors in the economics and feasibility of project development. Particular to gold and precious metal mining, waste disposal is further complicated by the environmental and political implications of the use of cyanide. Regulatory compliance criteria have partially dictated and can be anticipated to further dictate the approach and methods of tailings disposal. To develop practical, economic, and environmentally acceptable tailings disposal systems within these criteria requires the use of common sense approaches and the application of available technology. Waste disposal is typically considered during the pre-feasibility stages of project evaluation. At this time, the main emphasis is on the economics and practicality of extracting the metal values from the ore. Frequently, the result of this is that the nature of the tailings and the ability to dispose of the tailings is prejudged. It is also frequently the case, however, that during the feasibility stage and project permitting, the requirements for tailings disposal become paramount.

Jan 1, 1998

By Thomas R. Kuesel

All engineering designs are based on assumptions regarding the behavior of the structure or facility being designed. These assumptions may be based more or less heavily on theory, but are credible only if verified by observations of field performance. Dr. Peck's "State-of-the-Art" paper has described the semi -empirical process of soft ground tunnel design, emphasizing the importance of records of field performance of actual projects constructed under a variety of conditions. This paper will present the principal results obtained from measurements made during construction of the soft ground tunnels for the San Francisco Bay Area Rapid Transit System. SCOPE The BART System comprises 75 route miles, including 14 miles of soft ground tunnelled subways in San Francisco, Oakland, and Berkeley. All tunnels are single-track sections, approximately 18 feet in diameter. Usually there are two parallel tunnels at the same level, but under Market Street in San Francisco there are four tunnels (two over two), and there is also a three-track section (two over one) in Broadway, Oakland.

Jan 1, 1997

By Randy Ynchausti

ERIC GUTIERREZ, Knowledgescape: Our next speaker is Randy Ynchausti. He's the director of development, Knowledgescape systems division, of EIMCO Process Equip- ment Company. The title of Randy's talk is "An Expert Control System for Phosphate Beneficiation." RANDY YNCHAUSTI: System integration. How does the systems integrator survive when caught between plant engineers, plant management, and third-party engineering firms, and stay within the budget of the corporate goals? I'm not sure that anyone knows how to do all of that on one project. Results are critical when we talk about how systems integrators work with operating people, how the operating people want systems integrators to work with them, and how both groups work together so that at the end of a project, you have been provided with solutions that meet your needs and solve your problems at a fair price. How does the integrator's role change when working with different types of professionals, such as plant managers, plant engineers, engineering firms, or other system integrators? Finally, what is the dynamics of people working with machines and providing services and solving needs? The average number of employees per pound of copper processed has decreased significantly during the past 15 years. I would dare to generalize and say that the average number of employees per whatever unit of measure we have in whatever industry we work in has decreased over the last 15 years. From a system integrator's perspective, there are some clients who lack a bit of internal expertise as corporate downsizing occurs, and that's one reason why we go out to system integrators or third-party vendors and buy things from them to solve our problems. Downsizing really amounts to savings, but more than that, I think Brian expressed this and I agree with him, it also amounts to a cost. Unfortunately, most of us count the savings and none of us count the cost in that approach. It's easy to count the savings, which is one reason why we count it so quickly. Maybe that also accounts for why we set our pencils down so quickly after we get that dollar value. Maybe we should pick that pencil up every once in awhile and refigure the expense, the cost to us, and determine what we're going to pay during the next year or two or three in losing that expense, or that staff. A broad experience base accumulated over projects at various plants helps system integrators to provide services to clients. This experience enables the system integrator to

Jan 1, 1998