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At the dawn of the computer age in the early 1950's, few people in either the minerals industry or the field of electronic data processing (EDP) would have predicted the tremendous impact that the computer has had on the way we conduct our everyday lives and businesses. Herman Hollerith himself (see next page), the Columbia University mining engineer 'turned statistician who developed the first punched card electronic tabulating machines for the US Census Office in the late 1880's, would doubt- less be amazed at the progress that has been made in the application of data processing techniques to nearly all aspects of the mining cycle (Aul, 1974). More than any other factor, the availability of economical computing equipment has led the way for the development of the broad range of mining computer methods described in this text. While limits have been identified for many of the technologies commonly in use today, new technological advancements point to continued exponential advancements in computing price-performance in the 1980's. With those advancements, we may look forward to continued expansion of the role computers will play in mineral production.

Jan 1, 1979

By M. A. Trevits, R. J. Matetic

Mining operations have long been accused of causing a disruption to local, domestic and agricultural water supplies. More recently, concern for water supplies has increased with the advent of high-extraction mining techniques, namely longwall mining. Theoretically, any water-bearing zone in the overburden above a high-extraction mining operation may be affected by mining. In some cases, a confining bed may be fractured causing a loss of water to a particular zone. In other cases, increased fracture permeability may enhance the ability of an aquifer to transmit and deliver water. Unfortunately, only a limited number of studies have been conducted that characterize hydrologic changes and also quantify the magnitude of mining-induced subsidence. The US Bureau of Mines (USBM) conducted such a study at a mine site in Greene County, PA. A total of eight water wells were drilled, and hydrologic parameters, such as specific capacity, transmissivity and well yield, were determined both before and after mining. Electronic water-level recorders were installed on each water well to provide continuous observations of water level fluctuations.

Jan 1, 1993

By James A. Strosnider

INTRODUCTION The Metro Rail Project is approximately a 20-mile initial portion of Southern California's planned 150-mile transit network and will provide transit service to the dense population and employment centers within the Los Angeles regional core. The Southern California Rapid Transit District (SCRTD) has defined, as the first segment, a 4.4-mile five station rail line, which extends from the yard and shop area near Union Station to the Wilshire/Alvarado Station. Design packages are completed; utilities are currently being relocated; demolition is underway; early construction contracts have been awarded; and construction has started. This paper will describe the current status of the Metro Rail design and construction, after first briefly reviewing its history, objectives, and main components. PROJECT HISTORY The California State Legislature created the SCRTD in 1964 with a legislative mandate to design, construct, and operate a rapid transit system within the Los Angeles County area. To obtain the monies required to support this program, in June, 1974, Proposition 5 was passed by a solid majority, allowing a portion of state gasoline taxes to be used for rapid transit development. This measure provided a local source of funds for SCRTD to begin its rail rapid transit development program in Los Angeles.

Jan 1, 1987

By Numan Elmas

Barite deposits located in Dinek and surrounding region have important economic features with their large reserve capacity for Turkey. The objective of this study is to elucidate geological and depositional characteristics in terms of. site investigation and chemical analysis. In order to do this, geological area of about 300 km2 was examined and detailed geological map was constructed. It was observed that Barite mineralization in these deposits was occurred in carbonate and pelitic rocks of Lower Cambrian-Lower Ordovician. Deposits were exposed to advanced diagenesis regional metamorphism and tectonics that rotated and deformed the barites; therefore, barites shows secondary veins, brecciate and fracturing structure. Even though, a few light isotope values of barites may suggest hydrothermal and exhalative sedimentary characteristics or possible mixing with magmatic fluids, generally heavy isotope values indicate that the sulfate ions were supplied from coeval seawater and, many of sedimentary features and petrological, geochemical characters support dominantly sedimentary origin.

Jan 1, 2005

By A. K. Sheik, W. G. Pariseau

A small underground mine in northern Idaho was used as an experimental facility for studying the role of water in the analysis of mine-opening stability. Laboratory test data, borehole measurements and geological mapping assisted in the construction of a coupled finite element model of the rock mass. The model was used to make quantitative estimates of rock stress, strain and displacement changes and to make estimates of the water pressure and flow velocity changes that occurred during historical mining. Stope cuts and wet fills were included in the analysis. The stability of the crown pillars between stopes was of particular interest. The relatively low effective stress and high rock-mass strength showed that water pressure changes were of no great consequence, which is in agreement with experience. The computational tools used in the analysis may be applied to other wet mines with appropriate changes to site-specific data.

Jan 1, 2002

By Richard W. Hornung, Steven Samuels

A great amount of work in recent years has been devoted to refining older survivorship models, e.g. life tables, and developing newer ones, e.g. Cox regression. In this paper, these models are applied to data from an epidemiological study of uranium miners in four western states conducted by the U.S. Public Health Service. One of the principal problems addressed in this paper concerns the appropriateness of using cumulative dose as the measure of radiation exposure. An alternative is considered that incorporates dose rate into the model. This procedure does not implicity assume that equal cumulative doses produce the same lung cancer mortality, but instead considers the amount of time in which each miner's dose was accumulated. Results of the statistical analysis indicate that dose rate is a significant factor at higher cumulative dose levels, with lower dose rate apparently more damaging than higher dose rate. The shape of the dose response curve is curvilinear at higher dose levels. No interaction was found between smoking and radiation exposure on a multiplicative or relative scale.

Jan 1, 1981

By P. W. Hynes

Tg Soda Ash has operated a shortwall mining system in the Green River, WY trona district since August 1982. The system has proven to be highly productive. In an effort to reduce the amount of relatively expensive development mining and improve mine planning flexibility, a method to mine the return air tailgate during the shortwall retreat was tested beginning in April 1987. As of June 1988, four shortwall panels had been completed using the advancing tailgate, producing more than 739 kt (815,000 st). This paper discusses the effects of the advancing tailgate on shortwall production, development mining requirements, costs, strata mechanics, and ventilation. Shortwall mining is a hybrid extraction method combining the self-advancing hydraulic roof supports from longwall mining and continuous mining machines (Fig. 1). The technique has been only marginally successful at the majority of the nearly 20 installations worldwide. At present, the face at Tg Soda Ash Inc. is the only shortwall operating in the United States and the only noncoal shortwall in existence. Despite the method's record of limited success, the staff at Tg Soda Ash determined that the conditions in its trona mine were well suited for shortwall mining. The commitment to install a shortwall was made in late 1981 and the first panel commenced in August 1982. Between that time and June 1988, about 3.33 Mt (3.67 million st) of trona have been mined with the system from 15 panels. Annual average productivities have ranged from 818 t/shift (902 st per shift) in 1982 to 1.4 kt/t shift (1591 st per shift) in 1987. Overall, the system has produced an average of 1.3 kt/ shift (1450 st per shift). In April 1987, a method of mining the return air tailgate during shortwall retreat was tested (Fig. 2). The objective was to determine if a return airway could be established and maintained by mining a series of rooms and pillars about 7.6 m (25 ft) past the face support line. The method would allow a barrier pillar to be left between shortwall panels without requiring the mining of a separate return air tailgate.

Jan 1, 1990

By B. Cavender

Mining managers trying to rapidly reduce production costs tend to implement a traditional set of topdown managerial practices: reductions in production volume, employee layoffs, renegotiation of supplier contracts, cancellation of employee training, restrictions on travel, reductions in office supplies, and so forth. While these practices do reduce costs, the benefits are often limited in both magnitude and duration, and the workforce is usually left demoralized. Successful cost-cutters take a different approach. They make the continuous reduction of costs a priority for all members of the organization, whether managers or workers. The culture of these firms emphasizes the commitment, voluntarily given, of individuals and work groups to this goal. Cost-cutting practices often reject all of the traditional methods mentioned above, but are far more numerous, innovative and successful. This culture of cost reduction is the result of a set of leadership competencies that establish direction for the organization, align the organization's various constituencies with this direction, and motivate and inspire the organization. Cost reduction then becomes a routine task rather than a heroic achievement.

Jan 1, 2002

By Jack S. McPartland, Gene E. McClelland

It is advisable, for any heap leach project, to develop an historical metallurgical data base to predict production heap performance before ore is mined and placed onto the heap. A data base would include results from: interval assays, cyanide solubility tests, and bottle roll tests on exploration drill cuttings samples; and those results plus column leach test data on diamond drill core or bulk ore composites. Subsequent larger scale heap leach test data can then be compared to the historical data base, to blast hole composite data during mining, and eventually to production data. This paper does not discuss metallurgical comparisons between assays, cyanide solubility tests, and bottle roll tests on exploration drill cuttings samples, but does discuss metallurgical comparisons from bottle roll tests, laboratory scale column leach tests, and pilot scale heap leach tests on core and bulk ore samples with operating data for three U.S. commercially producing heap leach operations. Provided that representative core or bulk samples are used for evaluation, heap leach test results accurately predict or understate the success of the commercial operation and remove most of the uncertainty from the investment decision.

Jan 1, 1990

This paper details the development of a functional work index that characterises the relationship between the energy that is imparted by a Roller Press into materials, against the resultant size reduction achieved. Such a Roller Press work index is necessary for this new grinding technology to differentiate it from Bond's grinding work index, and to clear up confusion that arises with such a comparison to Bond. The energy usage in a Roller Press does not follow Bond's "Third Theory of Comminution" but rather Rittinger's theory of new surface creation. The relationships for such a work index have been developed from the viewpoint of an equipment manufacturer with the hope that they will be of assistance to the minerals industry in the design of grinding circuits incorporating Roller Press comminution. The work index contains modification factors that reflects the effect of oversize, fines, moisture. closed-circuit operation and roll surface characteristics on the energy verses size reduction relationship. It has evolved from the results obtained from testing of a wide range of ore and mineral types that include bauxite, coal, kimberlite, limestone, iron and chrome ores, base metal and gold ores. The results show that even for such a diverse range of materials, they all demonstrate similarities of behaviour when comminuted in a Roller Press.

Jan 1, 1997

By M. K. Gangal, E. D. Dainty

CANMET/MRL has been contributing to an industry/government program to assess the quality of air in mines, and improve the working environment for Canadian miners. The ultimate aim of this program is to recommend a sampling methodology and appropriate concentration limits for both the soot (diesel particulate matter - DPM) generated by diesel equipment, and respirable combustible dust (RCD) as measured underground. The program was conceived by the Canadian Adhoc Diesel Committee, which consists of representatives from seven major Canadian mining companies, three provincial inspectorates, one union representative, two manufacturers of diesel equipment, and CANMET, a Federal Canadian research agency. This paper describes the modification and laboratory confirmation of an existing methodology for the sampling and analysis of DPM/RCD, including: sampling problems, filter selection, filter efficiency, DPM size distribution, the approximate performance of fractionating devices, and it reports the results of current ambient measurements of exposure levels in Canadian underground mines. Because of the concern about the health impact of DPM/RCD on mine workers, North American agencies are in the process of establishing limits for these aerosols. So far, the Province of British Columbia is the only jurisdiction in North America to legislate the maximum exposure level of RCD in its underground mines, i.e. 1.5 mg/m3 interim level recommended by the Adhoc Diesel Committee. It has also recommended the use of the CANMET/ADHOC RCD sampling protocol.

Jan 1, 1993

By D. B. Apel

Rock mechanics software plays an important role during the design process of modern underground mines by allowing for verification of the stability of the planned excavations. The paper describes the methodology used to plan and locate the permanent underground openings at McArthur River Mine with the assistance of numerical modeling software.

Jan 1, 2004

By K. I. Cunningham, C. S. Spirakis

Two types of native sulfur deposits have been found in Lechuguilla Cave: thin late-stage crusts and massive early- formed deposits. Most, if not all, of the crusts appear to have formed by remobilization of native sulfur contained within gypsum and sulfur masses. The process is occurring today and is slowly converting the sulfur to gypsum. The absence of primary gypsum or reductants in the cave indicates that the early-formed massive sulfur deposits did not form by in-place reduction of sulfate, which is the process that formed the commercial sulfur deposits in the Delaware basin. Instead, it appears that H2S dissolved in basinal brines was oxidized by oxygen in near-surface ground waters in the cave. Fluid- inclusion data, which suggest the presence of both fresh water and saline water as the sulfur formed, support this interpretation. Although individual sulfur deposits in Lechuguilla Cave are no more than several tens of metric tons, the abundance of secondary gypsum (as much as 10 meters thick) indicates that native sulfur may once have been much more extensive.

Jan 1, 1992

By Fabio Amaya, Andrés Marulanda, Ramiro Gutiérrez, Alberto Marulanda

The behavior of a salt rock mass is strongly related to a creep phenomenon. The amount of creep depends on the level of stress generated in the underground excavation. Additionally, security conditions and the lifespan of an underground cavern excavated under this geological conditions depend on the evolution of creep. Based on the experience of the failure of the Old Underground Salt Cathedral of Zipaquirá(Colombia) and the construction of the new one, the theoretical framework to predict the creep behavior of a salt rock mass is explained. The theoretical formulations are calibrated based on actual observations of the material behavior to predict the lifespan of this striking structure.

Jan 1, 2003

By Byron N. Cooper

The Revenue Act of 1926 provided for five simple categories of natural resources to have the benefit of depletion allowances. In the 1947 Revenue Act, the number was increased to twenty-five, and in the 1951 Revenue Act to fifty-four. Of this number, fourteen were allowed 5 per cent; nine, 10 per cent; twenty-nine, 15 per cent; one, 23 per cent; and one (oil and gas), 27.5 per cent. The 1951 Revenue Act created a host of difficulties, including application of the "end- use criterion" and determination of the commonly accepted meaning of such terms as limestone, dolomite, chemical- and metallurgical-grade limestone, marble, calcium carbonates, and magnesium carbonates. Dolomite, for example, was listed at 10 per cent depletion allowance, but without definition. In the great amount of litigation growing out of the 1951 Revenue Act and its administration, it became essential to understand the derivation and subsequent usage of these common geologic terms. One thing that became clear was that our definitions changed significantly between the time that the 1951 Revenue Act became law and the time that later cases were tried. Some geologists neglected to learn about first usages of such terms as metallurgical limestone, and about meanings that were applicable when the 1951 Revenue Act was written and passed. Legal meanings in this paper are discussed in the light of certain famous cases that have been tried and settled.

Jan 1, 1966

By Gerhard Mücke

Geothermal and operational reasons in the German coal mining industry make it necessary to an increasing extent to climatize coal faces and headings by means of refrigeration plants. Air coolers installed on coal faces as well as in gateroads play an important part in such climatization. They must transfer, under difficult conditions, the refrigerating capacity supplied by central or de-central refrigeration plants from the chilled water to the air in the workings. The performance data of two new types of coalface coolers and of two different types of gateroad coolers were measured in two testing stations under different thermo- dynamic conditions with dust-free fresh air. As air coolers must be installed particularly at working points with a high .dust load the heat exchanging surfaces are fouled for the most part causing an essential reduction of the refrigerating capacity. The investigations therefore were extended to measurements with a certain dust load in the intake air of the coolers.

Jan 1, 1980

By M. J. Virnig, C. P. J. Van Vuuren, A. J. Botha

The Zadra, AARL and organic elution processes and variations of them are presently widely used to recover gold from activated carbon. Despite this the study of the kinetics of elution have received relatively little attention. It is the aim of this study to investigate the rate processes taking place during elution in both inorganic and organic solutions. Batch adsorption and elution rate and equilibrium experiments were performed. The spatial concentration of gold inside carbon particles at various stages of the adsorption and elution processes were measured with a scanning electron microscope using an image analyzer to control and manage the micro-analysis data. The activated carbon particles exhibited film and intra-particle mass transfer rate- controlled behaviour during adsorption in a caustic aqueous solution at 95°C. Elutions in the aqueous caustic acetone solution at 30°C and the caustic aqueous solution at 95°C were unaffected by change in stirring rate. Elution was modelled by desorption reaction rate-control at the outer surface of the carbon particle. Adsorption and elution isotherms under duplicated solution conditions showed reasonable agreement for the inorganic solution and a large disparity for the organic solution.

Jan 1, 1993

By R. J. Hickson

From 1993 through 1999, Cyprus Amax Minerals successfully completed eight major construction projects around the world. Six greenfield mines were brought into production, an ongoing operation was completely modernized and an environmental issue was appropriately remediated. The projects stretched over three continents: from arctic Russia to the Atacama Desert, from sea level to an elevation of 4,900 m (16,00Oft), from city suburbs to remote wilderness and from a low of US$130 million to more than US$ 1billion. The operations included open-pit and underground mines, mill and leach facilities and involved gold, copper, molybdenum and coal. The diversity of these projects inspired Cyprus Amax to create a "best-practices” project-management protocol to steer corporate expansion in the new millennium. This paper summarizes these best practices, while highlighting the project-management pirfalls to avoid.

Jan 1, 2000

By John A. Herbst, Per-Olaf Samskog, Jan Bjorkman, Yi Chang Lo

The study described here is concerned with the development of a model for the simulation and optimization of a rod milllpebble mill circuit. A series of laboratory tests was conducted to investigate the effect of critical operating variables. The pebble mill model structure used was a population balance type which accounta for impact breakage and fines production from pebble wear. Model parameterization and verification were performed using data obtained in batch tests and in a plant test campaign. The model developed was found to provide accurate predictions of plant-scale grinding. The prediction errors are less than 21 for the product size and 31 for the mill power required to achieve that product with a mill volume scale-up of 14,000 to 1. These results indicate that accurate extrapolations from laboratory batch data to plant scale performance are poaaible using the population balance model and scale-up prediction procedures for pebble mill circuits as well as ball mills. Preliminary indications are that the new model developed here will provide vital input for pebble mill optimization and process control as well as pebble mill design.

Jan 1, 1990

By M. J. McPherson, P. Mousset-Jones, G. Danko

Ventilation and refrigeration fortune climate modification contributes significantly to the operating costs of a deep hot mine. Mine climate simulation programs can he used to minimize the impact of these costs. There are several computer codes available to assist in this work. Whichever simulation program is used, it is the mine ventilation engineer who must supply the input data. This paper raises and answers the following question, namely, what accuracy is required of the basic input parameters, in order for a certain precision to he obtained in the predicted air temperatures? In the first part of the paper a new approach is described to estimate the dry and wet bulb temperature of the airflow, either in a dry or wet roadway. The calculation procedure allows an arbitrary temperature change with time, using Duhamel's superposition solution. Matrix-vector representation is applied to simplify the computational structure. In the second part of the paper the sensitivities of the dry and wet bulb air temperatures are analyzed, to the changes of the rock thernrophysical properties, the heat transfer coefficient, and the wetness factor.

Jan 1, 1987