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By S. J. Jung

The prime criteria in the design of underground openings with complicated geological structures is ground control. Stability of underground openings for deep mines is critical because incorrect orientation or geometry of shaft, stope, and accessways often results in the failure of openings due to high stress conditions. Current design procedures for complicated orientation and geometry of mines are rapidly becoming inadequate as mines are being developed. In this study, finite element method has been used with optimization criteria to design more stable and safe underground openings.

Jan 1, 1993

By Steve Kral

The list of environmental issues facing industry in general, and the mining industry in particular, has placed greater emphasis on the concept of risk assessment and risk management. In informal terms, risk can be defined as the chance of injury, loss or damage. More formally, it is defined as the probability of an occurrence and its consequences. In simple terms, risk assessment involves three questions: What can go wrong? How probable is it to go wrong? If it goes wrong, what are the consequences? Experts on the subject of risk assess¬ment and management met in St. Louis, MO in October 1992 to discuss the extensive and innovative technology that has been developed in this arena. Each agreed that a consistent framework can be used to approach risk assessment/ management considerations in siting and design alternatives, as well as when considering financial aspects of mine development. And the environmental planning process for mines, as well as planning for operation through closures, will rely more heavily on risk assessment and management techniques. Risk assessment is a tool to assist engineers, scientists and managers make better, defensible operational decisions. A realistic and probabilistic risk analysis, coupled with a sound financial model, can combine a large set of alternatives and criteria to arrive at a defensible decision. Organizers of this regional SME conference believe that mining professionals should become fully conversant with risk assessment techniques and approaches because this arena provides opportunities to develop more rational decision-making techniques. Current health risk assessments rely heavily on Environmental Protection Agency (EPA) approaches. Several speakers and papers show how this approach has been applied to a variety of topics. Two major advantages come forward when applying risk assessment techniques to environmental clean-up options for contaminated sites. They are the selection of practical options and cost-effective alternatives. A probabilistic risk assessment provides results that can be directly related to clean-up costs. It has been shown that small reductions in risk are obtained for large increases in cost after a certain threshold value is reached. A preferred, practical clean-up alternative that provides permanent solutions can be selected based on a probabilistic assessment. Here are summaries of some of the papers presented at the meeting.

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 T. D. Murphy

In the fall of 1988 it became evident that the accuracy of sulfur forecasts for Monterey Coal's No.1 Mine needed to be improved. In addition, it became necessary to predict if any individual train shipments during a month would exceed a contract sulfur limit. The challenge was to develop a forecasting process that would take into account the variability of the coal in the ground as well as the difference between laboratory and preparation plant sulfur reduction efficiency, and the effects of mining coal with multiple units. This paper describes how geostatistics and simulation techniques were used to meet this challenge.

Jan 1, 1992

By L. P. Hendriks

Consolidated Murchison, the only antimony producer in South Africa, is situated in the northeastern part of Transvaal. Phalaborwa, an important copper/phosphate mining town is situated about 60 km to the east of Consolidated Murchison, on the border of the Kruger National Park. The mine is jointly controlled by Johannesburg Consolidated Investment Co. Ltd. (JCI) and Anglovaal Limited.

Jan 1, 1998

By D. E. Munson

To assure the safety of a radioactive-waste repository, the performance of the repository must be predicted far into the future. The Waste Isolation Pilot Plant (WIPP) Program is responsible for developing the technology for such performance predictions in bedded salt. An important technology-development activity concerns the, fielding of very large-scale in situ tests to determine the time-dependent deformation of underground openings in salt as a basis for validation of the predictive technology. This technology is necessary to predict repository seal performance and final closure times of rooms and may be of value to the salt and potash mining community, as well.

Jan 1, 1992

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

GENERAL HYDROLOGIC REGIME The total hydrologic cycle must be considered when evaluating potential ground water problems in a mining environment. Precipitation is the ul¬timate source of all surface water and essentially all ground water. Stream flow during low flow periods often orig¬inates as seeps or stream gains (base flow) where the water table intersects the land surface. A stream that is higher in elevation than the ground water system may lose flow, thereby recharging the ground water system. The magnitude of stream gain or loss is dependent upon the hydraulic conductiv¬ity and related properties of the underlying hydrostratigraphic units. Ground water moves constantly from recharge areas to discharge areas (streams and springs) usually at very slow rates. Large quantities of ground water may be in¬tercepted in many underground mining environ¬ments. Construction of an underground mine in saturated formations may encounter ground water inflows ranging from very small to very large and from continuous to intermittent depending upon the hydraulic properties of the hydrostratigraphic units penetrated. SURFACE WATER VARIABLES Precipitation occurs in different forms, varying amounts, and with a wide assortment of temporal and areal distributions in the various mining dis¬tricts within the United States. Mine inflow can be affected in a matter of hours by precipitation events where there is a direct hydraulic interconnection between the mine and the surface through fractures or a mine opening. The timing, form, amount, and distribution of precipitation should be evaluated in a mine inflow study. A portion of the precipitation that falls in a topographic basin moves as sheet flow to runoff channels (Fig. 1). Some of the precipitation infil¬trates the unsaturated soil zone where it can either move laterally as interflow to the surface system to augment stream flow or move downward as re¬-charge to the ground water system. The unsatu¬rated zone (called the zone of aeration or vadose zone) can range in thickness from essentially zero to a few hundred feet. The saturated zone or ground water system occurs below the water table (zone where hydrostatic pressure is greater than atmos¬pheric pressure) where all the pores are filled with water (Freeze and Cherry, 1979, p. 44). Moisture can be lost from any of the systems (surface water system, unsaturated zone, and ground water sys¬tem) by the processes of evaporation and transpir¬ation which return moisture to the atmosphere. Stream flow consists of runoff and interflow components plus an additional base flow compo¬nent (Fig. 2). Base flow constitutes ground water discharge to a stream. Base flow plays an increas¬ingly significant role as total stream flow declines. Base flow is important because it constitutes much if not all stream flow between periods of precipi¬tation when runoff and interflow have largely dis¬sipated. INTERACTION OF SURFACE WATER AND GROUND WATER SYSTEMS Recharge from a surface water system to ground water systems can occur via unsaturated or saturated flow. The amount of recharge is depen¬dent primarily upon the vertical hydraulic conduc¬tivity of the formations underlying the stream and the availability of water. Streams that flow over low hydraulic conductivity formations lose little water even if the ground water levels are significantly lower than the stream. A ground water system may contribute flow to a surface water system but nor¬mally only by saturated flow. This contribution usually takes the form of seeps, springs, and the base flow of streams. GROUND WATER VARIABLES Introduction The variables that affect ground water flow are discussed in increasingly complex theoretical situ-

Jan 1, 1986

By Charles E. Joachim

Current Army tunnel destruction criteria (1) are based on limited nuclear-explosive (NE) and high-explosive (HE) test data. The PILE DRIVER (2) and HARDHAT (3) events investigated tunnel and support system response where yields were relatively large and tunnel diameter small compared to typical underground openings and localized stress fields of low yield weapons. Some limited tunnel destruction information was obtained from underground events of the PLUMBBOB and HARDTACK II Series (4). These events used access drifts which were designed to be self closing at the weapon point. The limited NE data are augmented by HE results from the Underground Explosion Test (UET) Program, a series of model and prototype-scale experiments in granite and sandstone (5). Weapon standoff distances (charge c.g. to tunnel wall) were at or near the maximum for major damage. Limited tunnel destruction was produced by a series of hasty and deliberate tests (6) on abandoned railroad tunnels in basalt. Additional HE data were obtained from model tests at the Waterways Experiment Station (WES) (7) using 2.1 MJ (2 lb) TNT charges and tunnel diameters varying from 3 to 17 cm (1.2 to 6.6 in). Recent laboratory scale HE experiments (8) conducted at the WES under the ESSEX program investigated the effects of tunnel diameter, standoff distance, charge confinement, material strength and to a limited extent, tunnel spacing and liner strength variations on tunnel damage. This paper summarizes the analysis conducted to develop predictions for the effects of low-yield nuclear weapons against tunnels and underground openings in rock.

Jan 1, 1979

By D. Carlson

At the Freeport Indonesia Grasberg Mine in Irian Jaya, Indonesia, a system of underground drainholes and surface drain wells have been designed and are currently under construction. The underground drainholes are located at elevations of approximately 9,600 feet and the surface drainwells located at elevations ranging between 12,500 and 13,000 feet. Together they will be used to drain the ground water contained within relatively incompetent rock. This drain system will allow for the successful dry mining of the open pit, and provide slope stability of the pit wall. The surface drain well network, when completed will allow for the draining of ground water to the Amole Drift where the underground drainholes are constructed.

Jan 1, 1998

By Robert D. Talvensaari

It is indeed an honor for White Pine, as a member of the copper mining industry, to participate in this Rapid Excavation Conference. Although our presentation, as the title indicates, is not a success story, we foresee, through our experience, future application of boring machines and rapid excavation equipment in the hard rock mining industry. One might ask what a copper mining company would be doing with boring machines and why the gamble on a high-cost, capital investment for a relatively untried application. Perhaps a little background on the White Pine mine and its geology will explain our daring and speculative motives. THE WHITE PINE MINE The White Pine Copper Company, a wholly-owned subsidiary of Copper Range Company, operates a mine, mill and smelter at White Pine, Michigan in the western Upper Peninsula approximately 6 miles due south of Lake Superior. We employ approximately 3,000 people from the surrounding area and mine approximately 25,500 tons of low grade (1%) copper ore per day. The orebody is contained within several distinct sedimentary horizons that comprise the lower 20 feet of a Precambrian formation known as the Nonesuch Shale. Numerous articles and reports have described many aspects of the White Pine operation and the geology. I will brief you only on that criteria which precipitated our interest in rapid excavation equipment and techniques, specifically, boring machines. Mineralogical and optical studies have demonstrated that the siltstones, sandstone and shale beds all contain relatively barren and discrete particles of quartz (25%), feldspar and mica, bonded with

Jan 1, 1974

By D. M. Smith, M. J. Meulendyke, P. J. Moroz

An extensive program of marked ball wear testing (MBWT), laboratory corrosion studies, and worn ball surface analyses has been used to gain insight about the role of corrosion in the overall wear process. In some environments, localized corrosion is observed; the actual wear mechanisms in such cases are pitting/spalling and abrasion. Factors affecting the occurrence of pitting include the abrasiveness of the ore, corrosivity of the slurry, corrosion resistance of the media, and galvanic coupling effects. Elimination of pitting substantially improves overall wear resistance. When pitting is not observed, the contributions of general corrosion are significantly less.

Jan 1, 1988

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

7.1 INTRODUCTION Subsidence measurements include surveys of surface and sub- surface movements and measurements and monitoring of surface structural damages. In this chapter the most commonly employed methods are discussed. 7.2 MEASUREMENT OF SURFACE MOVEMENT Surface movements involve two basic components, subsidence and displacement. The other five components (i.e., slope, curvature, strain, twisting, and shearing) are derived from the two basic components. Since all measurements are geometrical, they can be measured by common surveying techniques. 7.2.1 MONUMENTS The first step is to select the types of monuments or surveying stations. Various types of monuments have been employed. The simplest one is a paint mark on the pavement or concrete slab, although this should be discouraged because it is easily affected by artificial or environmental factors. Others use steel or wooden rods, 2 to 3 in. in diameter or square by 2 to 5 ft long, driven all the way down, flush with the ground. Both types of-monuments have no provision for frozen ground heave and both are tampered with easily. A more elaborate type is shown in Fig. 7.1 (O'Rourke et al., 1982). A rebar or iron pipe, 2 in. in diameter by 6 ft long is driven down to nearly flush with ground surface. The top 4-ft section of the hole around the pipe is enlarged to 1 ft in diameter and grouted with concrete. The most sophisticated type of monument is shown in Fig. 7.2 (Conroy and Gyannaty, 1983a). It consists of two hollow steel pipes. The inner I-in. pipe, 10 ft. long is enclosed by a 2-in. pipe at the upper 5-ft. interval. The gap between pipes is filled with foam to isolate the inner pipe from external environmental effects. The bottom of the inner pipe can either remain open or be sealed with a cap, depending on whether the ground is dry or wet. 7.2.2 MONUMENT ARRANGEMENT AND SURVEY LINES The monuments are installed strategically to form survey lines. Three basic types of monument arrangements are shown in Fig. 7.3. Figs. 7.3a and 7.3b are for single and multiple panels respectively; Fig. 7.3~ is mainly for research purposes with multiple survey lines both in longitudinal and transverse directions. This is extremely useful for defining the distributions of ground deformation, as shown in Figs. 2.10 and 2.11. Basically there are two types of survey lines: the whole basin survey line which extends across the panel width or length (e.g., lines R, R, in Fig. 7.3 a&b), and the half basin survey line which covers approximately half of the panel width or length (e.g., lines R, F in Fig. 7.3 &b). Survey lines are generally straight and linear. They should be located on the major crosssections of the subsidence basin. Survey lines must extend beyond the edge of the opening for a sufficient distance so that the edges of the subsidence basin can be determined accurately. The minimum distance from the edge of the opening must be [ ] where h = mining depth, [ ] = angle of draw, and [ ] = 5 to 7 times monument spacing for whole basin surveys, or 8 to 10 times the monument spacing for half basin surveys. There must be at least two controlling monuments at each end of each survey line. Controlling monuments must be located beyond the influence of underground mining. The spacing of the monuments ranges from 15 to 200 ft. The UK National Coal Board (NCB, 1975) recommended a spacing equivalent to 0.20 of the mining depth. Peng and Geng (1982) recommended that the maximum monument spacing be dependent on mining depths as follows:

Jan 1, 1992

The successful exploration for Austin Taylor and Gen. McRae from 1931 to 1940 obscured the fact that I was reaching a period of transition. This was true both in personal and business life. It was probably fortunate that I did not realize how great a change must come after I passed the age of 50. In the personal life of our family the change came when both our children left home to go to school or college. This made home a different place and, because of the absence of the children, Dorothy could devote much of her time and attention to the art she loved so well. She could spend long periods in New York, the center of the nation's art life. Vacations at Tahoe and long pleasure trips made the separation from the children less disturbing but it could never again be the same as it had been in the first 20 years of our marriage. The change In my business life was just as complete, though a little more gradual. While work for Bralorne and General McRae made the "bite" of the Great Depression less painful for us than it was for most consultants and their families, the fact that I was getting older made a new sort of work inevitable. I was 50 years old and the total grew rapidly. Planes and automobiles that made travel easier even in the wilds of Alaska and northern Canada still made it possible for me to look at new prospects, but increasingly often I was exhausted at the end of a day's climb and, if the nature of my work did not change there would soon be no more work. Fortunately work of a new sort came a little at a time. As I became a director of Bralorne and president of its American subsidiaries I had to take on more administrative work, and success of these operations made others want to employ me to help direct policy and value mines. I was also asked to arbitrate contests between mines when technical disagreements were so great that judges or juries could obviously not understand them My consulting for government agencies helped to

Jan 1, 1976

By J de Cuyper, S. Ramachandran, L. A. Vazquez, N. L. Grauerholz, W. Freyberger

A novel process is described for the selective flotation of scheelite from low-grade (- 0.5% W03) tungsten ores having appreciable quantities of calcareous and siliceous gangue minerals. Specifically developed for the Tempiute, Nevada facility of Union Carbide, the process yields tungsten concentrates exceeding 15 percent W03 with at least 85 percent recovery. This condition was not achieved through conventional processes. This process consists of conditioning the ore pulp with judicious amounts of lime, followed by soda ash and sodium silicate as modifiers. The scheelite is then floated using a mixture of oleic and naphthenic acids as collector. Contrary to the common observation as to the deleterious effects of calcium in fatty acid flotation systems, lime addition is found to be beneficial in achieving satisfactory results. The process has also shown excellent results on a Brazilian scheelite ore.

Jan 1, 1976

By D. W. Niosi

In this chapter, a review is made of the various stages of an exploration program, mineral rights acquisition methods and the partners involved in an agreement, the after- tax cash flow approach using present value discounting principles, the establishment of computerized financial models for assistance during the negotiating stages for a mineral property, and the various evaluation techniques and their specific applications during different phases of an exploration program. A set of examples is shown encompassing the initial target-seeking stages to the ultimate feasibility study stage.

Jan 1, 1979

By G. Jalkanen

Dealing with a trend in inverse distance estimation, IWD, is presented. A measurement is proposed to be consisted of a portion due to a mean and a portion due to a residual. The procedure consists of de-trending the measurement via a linear or nonlinear regression. Residuals are computed, and IWD parameter estimation is conducted on the residuals. Estimation at un-sampled points is then computed by estimating the mean and adding on the estimate of the IWD on the residual. A possible BOXCOX transform is also proposed.

Jan 1, 2010

By K. Y. Haramy, E. C. Westman

Anomalous geologic or stress conditions ahead of a longwall face have the potential of causing great harm to both the individual miner and the mining operation as a whole. NSA Engineering has been developing seismic tomography techniques to image the panel ahead of the face. This paper presents the results of afield effort in which a 60-m (200-ft) segment of a longwall panel containing a fault zone was surveyed daily as the face approached. Stress distribution, geologic structure and dynamic elastic properties within the panel were plotted and compared to static laboratory measurements. The surveys successfully imaged an anomalous stress concentration that was likely influenced by the presence of the fault zone. The calculated dynamic physical properties generally agreed with the laboratory measurements.

Jan 1, 1997

By Jean-François Boucher, Ernest K. Yanful, Mei Lin Shelp, Lionel J. J. Catalan

Shallow water covers for preventing acid production in tailings are based on the principle of minimizing oxygen availability. Resuspension of material from the tailings bed may result in increased oxidation and metal releases since dissolved oxygen is at near saturation levels in the water cover. Resuspension can be caused by waves and currents strong enough to mobilize the surface of the tailings bed. Tailings resuspension was measured with sediment traps in the Upper Cell of the Heath Steele site near Mirarnichi, New Brunswick Canada. Although significant amounts of resuspended tailings were collected in all traps, analysis of resuspended solids and bed tailings suggests that for the observed wind conditions resuspension did not occur at locations where the water cover depth was greater or equal to 1.0 m. Currents were likely responsible for the transport of resuspended tailings from shallower areas to locations where the water cover was deeper than 1.0 m.

Jan 1, 2000

By C. J. Webb

Abandoned uranium mines in the southern Black Hills of South Dakota were sampled for uranium, radium, and rare earth elements during 1992 and 1993. Analyses of water samples from several shallow ponds in the mine pits showed pH values between 3 and 4 with uranium concentrations between 1600 and 2600 ppb. Rare earth elements and their respective isotopes were analyzed with an inductively coupled plasma mass spectrometer and were referenced to a shale normalization pattern. All samples showed an enrichment in the middle rare earth elements. Rare earth levels often were greater than 0.2 ppm. At one site, the concentrations of lanthanides were 150,000 times above background levels. While the southern Black Hills have long been known for rich uranium ore deposits, these analyses show that significant levels of rare earth elements also are present, indicating that the potential exist for future development.

Jan 1, 1995

By M. C. Williams, T. P. Meloy

With the increasing power of computers to simulate and control processes in the mineral industry, predicting the potential use of computers in the minerals field is not a hazardous enterprise, but predicting the timing of their use is. Like the railroad industry, technology invades the mineral industry, rather than being an industry like electronics that creates technology. Because of this invasive nature of computer technology in the minerals field, this paper predicts what will be possible to do effectively and economically with computers in the mineral industry. Moreover, this paper explores the problems of using the emerging computer technology in the mineral industry. For example, if not now, it soon will be possible to control the output of a mineral processing circuit - high grade, high flow or a mixture of it - to meet the daily market conditions and to sell each day that daily "mill" output as "mill" futures on the commodity market. Finally, suggestions are made which may be done to prepare the industry for the computer revolution in the mineral industry.

Jan 1, 1993