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By C. Sun

Due to unfavorable geological condition, excessive deformation of mine drifts occurred in a large underground copper and nickel mine. In searching for a solution, a comprehensive underground monitoring program was implemented and the opening convergence and the surrounding rock deformation were monitored. A large number of field data were collected and thoroughly analyzed. The convergence and deformation as function of time and depth were determined and a rock stability index was proposed. Based on the deformation-time and deformation-depth relations, critical deformation times and locations were identified and defined as characteristic values to be used for mine opening and support designs. The characteristic values are critical in the application of two-step supporting system, and the determination of support parameters. The application of the method developed in this study has demonstrated that this practical approach in support design and installation is effective. With the two-step supporting system, a long-term drift stability can be achieved in the mine.

Jan 1, 1998

By John P. Albers

During the 1950's and 1960's a program of geologic mapping of counties has been underway in Nevada by geologists of the U. S. Geological Survey and the Nevada Bureau of Mines. The aping has been done principally at reconnaissance scales, with more detailed work in local areas. Geologic maps are either published or open-filed for about a dozen counties at scales of 1:200,000 or 1:250,000. One by-product of the geologic mapping has been the recognition of about 80 Tertiary volcanic centers from which large or very large volumes of volcanic material ranging from rhyolitic to andesitic in composition have been erupted. For purposes of this discussion these are regarded as the major centers; the tally does not include hundreds and perhaps thousands of small rhyolitic domes and plugs and basaltic vents. About 15 to 20 of the 80 major centers are believed to be calderas ranging in diameter from 3 to 25 miles. Some have been described in the literature by geologists of the Nevada Test Site and others. However, the vast majority of the 80 centers have not been described in print, and we are indebted to our colleagues for locating them for us in many of the counties. Briefly, we would like to express our appreciation to the following people all members of the USGS unless identified otherwise: Robert Coast, who has identified the centers in Elko County; Ron Willden, Robert Yates, and

Jan 1, 1968

By T. Martinez Patino

Precious metals have been sought by man through time. The search has been the cause of many historic events as well as the founding of the famous Mexican, Minion centers of Durango, Guanajuato, Zacatecas and others. Bacis, a silver - cold deposit in the State of Durango was one of the lesser known centers established during Spanish colonial times. During the past year, metal prices have suffered a substantial decline, resulting in the closure of many mines. Through astute exploration, development and exploitation of the mine, the effect of the low prices has been offset and the mine is surviving these hard times.

Jan 1, 1994

By Thornton L. Neathery

A small area in the Alabama Piedmont was studied to determine if metallic enrichment was associated with local magnetic anomalies. Cores from two holes in these magnetic anomalous areas have sulfide (pyrite, pyrrhotite, chalcopyrite) film on slicken-side and fracture surfaces. Two hundred and fifty soil samples were collected from the top of the "B" horizon on 1, 000 foot centers over the general trend of magnetic anomalies. Soil samples were leached with a 1:2. 7 mixture of HF and H2SO4 and the dilute filtrate analyzed for Cu, Pb, Zn, Ni, Co, Cr, Mo, and Cd, using atomic absorption methods. Concentration-value maps were prepared for each element. Small areas of anomalous concentrations were defined for Cu, Pb, Zn, Mo, and Ni. Some of these areas generally coincides with magnetic anomalies. Concentration values (ppm) range from: Cu 165.0 - 0. 5; Pb 265. 0 - 0.0; Zn 1386.0 - 43. 0; Ni 187.0 - 10.0; Co 207.0 - 6. 5; Cr 117.5 - 2.0; Mo 95.0 - 0.0; and Cd 32. 5 - 2.0. Studies of other magnetic anomalies appear warranted.

Jan 1, 1972

By D. Hodouin

The paper reviews approaches to estimate in a real time fashion consistent mass flowrates and assays, using data from the on-stream analyzers and flowmeters of a flotation circuit. Results obtained with one algorithm operating on-line with an industrial flotation circuit are presented.

Jan 1, 1996

By C. Newman, N. Schaefer

"As underground mining continues to operate at deeper depths and in more complex geologic and geometric conditions, there has been an increased demand for mine designs to better reflect site-specific conditions, measurements, and observations with respect to ground control safety and stability. During the past 20 years, the National Institute for Occupational Safety and Health (NIOSH) has developed, validated and distributed a number of free software packages (ALPS, ARMPS, AMSS, ARBS, etc.) specifically aimed at providing the industry with ground control design tools for the evaluation of underground stability in coal mines. While these programs were initially developed as stand-alone software packages where all data reside on an individual or workgroup computer, modern day web applications have begun to migrate toward a “multiple-tier” architecture, allowing multiple users to access an application by means of an Internet connection.This article introduces a new Web-based platform for ground control software applications, webGroundControl (webGC). webGC provides users with a platform through which one can access NIOSH and other ground control design software utilizing a Webbased, multiple-tier architecture. This provides users with easy access to ground control designs, the ability to perform on-demand calculations, as well as increase online collaboration between operational personnel and engineers through a web server. The basic framework and, more specifically, the user-interface of webGC are defined and outlined within this paper. It is expected that the mining industry will rapidly embrace this new product and webGroundControl will be a new paradigm for mining engineering computer applications. Platform architectureAs Web-based computing technologies continue to advance and cloud computing gains momentum, web-based platforms for software applications are growing in popularity across all industries due to ease of product accessibility and distribution as well as data security. With the expansion of Internet connectivity on the surface and underground, there is an industry need to develop Internet-based applications for mine and ground control design (Barczak et al., 2016). Cloud-based products are already available for many industries and are slowly being developed for the mining and geotechnical industry. A notable example is the drillysis package, which is a cloud-based borehole logging database (Geosysta, 2017) or the Dynonobel package for on the fly blasting calculations (Dyno Nobel, 2013)."

Jan 10, 2017

By D. Malhotra

Climax byproduct-plant tailing assayed 0.019 percent WO3. Pilot-plant and laboratory tests were performed to investigate the possibility of recovering additional tungsten values from the byproduct-plant tailing. The paper discusses the methodology used in the study and the results of this investigation.

Jan 1, 1985

By T. M. Needham

Increasing ore hardness led to a gradual reduction of mill throughput rates. This, combined with declining head grades and low gold price, prompted a review of milling practice at Kidston. Plant trials and computer simulation of the grinding circuit indicated the potential to increase mill throughput by up to 451 by reducing SAG mill feed size. Secondary crushing and additional ball milling capacity were installed. Commissioning was carried out successfully in September/October 1992. Design, operation and problems of the expanded circuit are discussed, and recent operating results are presented.

Jan 1, 1994

By T. K. McMahon

Formally, a mathematical model could be defined as: A set of equations whose solution will approximate the response of a physical process or system to a set of stimuli which appear as parameters in the equations. The purpose of a mathematical model is to permit the rationalization of experience to proceed by simulation rather than by physical experimentation. In the application of digital computer control to an industrial process, the mathematical model of the process (subsequently called the process model) is needed to calculate the present process performance from the measured variables and to predict the response of the process to a control change. Functionally, the cardinal element in process model development is a concise set of control objectives. These, besides implicitly defining the boundaries of the system to be modeled, will determine the accuracy demanded of the model its nature: dynamic or steady-state, and so forth, The objectives should explicitly define what process efficiencies, production rates, qualities are to lie within the scope of the computer control project, thereby providing a basis for simplifying assumptions in the development of the model. This requirement, a limited set of control objectives, is so often disregarded in formulating industrial control problems that its repetition can scarcely be avoided.

Jan 1, 1965

Roof bolting has been widely used in hard rock underground mines for its many advantages. In this paper, the applicability of roof bolts to mine openings in frozen ground and effects of bolts on the stability of the openings are presented. A comprehensive finite element program ABAQUS, was used to analyze the temperature distribution, the stress field, and the displacement field around a mine opening. Openings supported by roof bolts and unsupported were analyzed. The thermal and mechanical processes were treated as a quasi-coupled problem, with the thermal analyses being conducted first, followed by the mechanical analyses in each case. For the opening under consideration with a roof area of 15 m2, five to seven roof bolts are appropriate. When the number of bolts are less than five, the displacement within the ground can be improved only locally.

Jan 1, 1995

By Musa I. Marto

The theory of ore flotation has developed at a rather fast rate and the application of theory to practice has been successfully investigated. Significant technological advances have been made in such areas as control of the ore grade, automation in metallurgical control through conductivity measurements, and the development of faster and continuous analytical techniques for ore pulp analysis. Further significant improvements in mill control are being_ investigated through the application of a computer control to the process. This represents the more advanced trend in process control. At the heart of a control system installation, the digital computer will communicate directly with process instrumentation, perform' complex calcu¬lations to determine on a timely basis the control settings for attaining optimum results and automatically furnish signals to effect control actions. The process is considered as an integrated unit and economic criteria are used to measure its performance. The approaches to a mathematical model development to describe the process, optimization and control schemes as applied to an ore beneficiation process will be discussed.

Jan 1, 1962

By James L. Patton

Automation of mining increases the productivity of labor, thereby reducing the unit cost of labor. Such cost constitutes the largest portion of the direct or variable costs of producing coal. Therefore, any increase in productivity directly reduces variable cost. The large investment in mechanical equipment carries with it the burden of increased fixed charges. As the proportion of fixed cost to the total cost increases, the effects on the cost of production changes are amplified. Therefore, equipment must be fully utilized at all times. Averaged fixed costs rise with any decline in production. Such a situation forces coal companies to seek every means of main¬taining full production. Figure I will reflect the story on the relationship of production to cost.

Jan 1, 1962

By Sergio Godoy P.

The Los Bronces porphyry copper deposit is located in the high Andes of Central Chile. Ore is mined from several tourmaline breccias and from an earlier porphyry. After years of experience in the geostatistical estimation of reserves in different zones of the ore body, we believe that success lies in considering the evaluation as an integrated process beginning with the analyses of the drilling density and sampling methodology, ending with the critically important reconciliation between the estimated and the actually extracted ore, in general, when errors or differences occur, focus is centered in the calculation stages of geostatistics. However, this paper demonstrates that all the evaluation stages are equally important and require the direct and continuous geologic input to ensure the best possible estimate within the frame of the geologic constraints.

Jan 1, 1992

By Russell G. Hood

Rock bolting or anchoring are methods of stabilization which are not being fully utilized in California and probably in other parts of the world due to lack of understanding of the principles, or due to poor results in actual installation. The problem is greater in California because so much of the rock is either soft or badly fractured and broken. Almost any recognized type of rock bolt or anchor will perform successfully is hard, fresh rock, but the problems become many-fold when working in decomposed granites, shales, soft sandstones or other soft, highly-broken rock. There has been an enormous amount of research by manufacturers, consultants, private organizations, and governmental agencies on rock bolting. It would be impossible to discuss all the methods and philosophies of rock bolting in this paper. Therefore, with the indulgence of the experts, I will give only a very generalized coverage on rock bolting techniques. However, My main purpose is to point out some of the problems of rock bolting in soft rock.

Jan 1, 1967

By Gerald Pinter, David Nitsche, Márton Bredács, Markus Haager, Andreas Frank

"The reliable prediction of service lifetime of tunnel constructions is of essential technical and economic interest. Polymers used for tunnel liners have to fulfill the requirement of 100 years lifetime. However, today no reliably proven test method is available which confirms such long lifetimes. The current paper introduces a recently started research project which focuses on lifetime prediction of highly flexible, very low density polyethylene (VLDPE) for tunnel geomembranes. Different PE grades in combination with different antioxidant packages are conditioned at elevated temperatures and immersed in different media. Initial results confirmed significant material aging of unstabilized resins already after exposure of up to 34 weeks, at least at the highest exposure temperature of 80 °C. To consider application relevant material properties the material characterization was done by means of tensile tests and dynamic oxidation induction temperature tests. High pressure liquid chromatography was used for further investigation of antioxidant consumption kinetics. 1. INTRODUCTION For a reliable service of modern tunnel constructions a sustainable proofing against water infiltration is essential for the lifetime of the structure. Geomembranes made of polymeric materials have been used successfully for tunnel lining since several decades. Whereas previous geomembranes usually were made of plasticized polyvinylchloride (PVC-P), due to several technical advantages today very low density polyethylene (VLDPE) has become a more and more popular material for such applications. For modern geomembranes, current guidelines expect minimum lifetimes of at least 100 years (ÖBV-Richtlinie 2012). In contrast to this requirement it must be considered that today no test methodology is available which reliably confirms such long lifetimes of polymeric materials."

Jan 1, 2016

By L. Adler

To mine safely and efficiently the working conditions must be systematically de¬fined. Their uniqueness distinguishes mining from other engineering professions. The worst case in underground mining is delineated and termed "encumbered space'", since it "seriously impedes motion or action." Working space is inherently hazardous, transitory, and expensive, inducing it to be of low quality, tight and congested, vulnerable and deteriorating, and isolated and inaccessible. These adverse conditions, are damaging to cumbersome, mobile equipment, and affect all activities, including surface work. The conditions are reorganized using the fundamental engineering dimensions: space, matter time, people, and money. Comprehensive tables are presented with attention paid to "disaster potentials". Examples are cited.

Jan 1, 1982

By A. M. Laird

Endako Mines' molybdenum operation is located near the geographic center of the province of British Columbia, Canada. The property is six miles south of the Northern Transprovincial Highway and the northern main line of the Canadian National Railway. The area is broken by high hills covered with dense stands of spruce and pine with vast areas of the valley floors covered with aspen and poplar. The climate is moderate with precipitation averaging 22 inches per year. Approximately four feet of snow accumulates in the winter, and temperatures range from 900 F. in summer to -40° F. in winter. The orebody, a lowgrade porphyry type deposit, occurs in a widespread granitic intrusive which has been locally weakened at the intersection of two regional faults. In this vicinity the quartz monzonite has been further shattered to permit the entry of mineralizing solutions and local dykes. Two types of mineralization occur within the orebody. The most prom¬inent is the six inch to four foot wide continuous quartz veins with characteristic ribbons of molybdenite and frequently finely-divided grains of molybdenite within the quartz. The second type occurs as fine fractures filled with quartz molybdenite in the form of a stockwork halo radiating out from 20 to 200 feet from the quartz veins. Minor hematite, magnetite and chalcopyrite are also present. Mineralization is roughly proportional to the extent of kaolinization in the quartz monzonite, kaolinization being one of three distinct forms of hydrothermal alteration. Pyrite is commonly associated with molybdenum mineralization within the orebody and a pyrite halo is recognized on the south side of the orebody.

Jan 1, 1968

By W. L. Chen

In the United States hydraulic cyclones have been used for thickening, classification and cleaning in coal preparation plants for many years. The cleaning cyclones presently in use are based on using a "heavy medium", such as a fine magnetite and water pulp. The latest addition to cleaning cyclones is the one which uses ?water only?, or simply called "Hydrocyclone". Just as was the heavy medium cyclone, the hydrocyclones were originated in the Netherlands (1, 2). Plants using hydrocyclones were built in Europe (3) and test plants were erected in Canada (4, 5, 6) and India (7). Roberts and Schaefer Company has built four plants using hydrocyclone circuits. One additional plant is in the process of construction.

Jan 1, 1965

By C. L. Sarff

[Automation has become a word that means many things. To management it is the end of the rainbow; you push a button and all your problems are solved. To the working man it is a horrible monster that is taking his livelihood away. To the maintenance man it is a complex that overwhelms him when he thinks of trying to find the trouble when the machine is not operating, properly. Automation has been with us in the coal nines for many years. Long before my time you were using float switches on mine sumps to control the level of the water. That?s automation in the truest sense of the word, but we call it automatic and think nothing of it. If we use the word automatic instead of automation your mine electrician and mechanic will take hold of the problems in stride.]

Jan 1, 1962

By P. F. Mataich

When the subject of plant computers is brought up most people visualize the computer's controlling the entire plant with very little operator intervention. Actually, this picture is true today in only a limited number of cases and will certainly not be true in the minerals industries for many years to come. There are several ways in which a plant computer can significantly contribute to improving plant operation and closed loop control is only one of these. First of all, what are the basic ingredients for good plant control? For good plant control, two requirements must be met. First, the operator must get good information feedback from the process and then he must know what action to take in response to this information. Control information can be obtained through instruments, laboratory analyses, or through simple visual observation. If it is timely and accurate and the operator knows how to use it, then we have the makings of a good plant control system. The computer can be of help in both these areas by getting good data back to the operator and in helping to develop a good control scheme for the plant.

Jan 1, 1966