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By G. A. Parkison

The sequential copper analysis method is a particularly useful technique to semi-quantitatively define the geologic, mineralogic, and metallurgical types and zonations commonly associated with porphyry-type copper deposits. The method is based on the partial dissolution behavior displayed by the prevalent copper minerals malachite, chrysocolla, chalcocite, and chalcopyrite to solutions containing sulfuric acid and sodium cyanide. Results from sequential analyses of the sample and analytical residue using sulfuric acid followed by sodium cyanide and then aqua regia solutions when compared with conventional total copper analyses can determine the amounts of leachable oxide minerals, leachable secondary sulfide minerals, and primary copper minerals, respectively. Sequential assay analytical results and interpretation are presented for copper deposits in Chile, Mexico, and the United States.

Jan 1, 1995

By David W. Wisecarver

The U.S. Bureau of Mines, in cooperation with U.S. Borax and Chemical Corporation and the Kennecott Copper Corporation, has investigated the use of the microseismic method to evaluate the stability of large, open-pit slope walls. The method is based on the phenomenon that stressed rock normally emits subaudible rock noises, and the number of rock noises per unit time (noise rate) and the magnitude of the rock noises (amplitude) increase as the stresses in the rock approach the failure stress of the rock. Therefore, the detection and recording of those rock noises serve as a semiquantitative method of predicting the incipient failure of rock. This report briefly describes the three different types of microseismic apparatus, the procedures, and the results of microseismic investigations in the slope walls of the Boron Mine near Boron, California, and the Rimbley, Liberty, and Tripp-Veteran open-pit mines near Ely, Nevada. Microsesimic noise rates in stable inactive mining areas are between 0 and 10 noises/ hour; the rates in stable active mining areas are between 10 and 50 noises/hour; and the rate in unstable areas is as high as 2500 noises/ hour. High microseismic noise rates in the Liberty Pit correlate with the time of nearby earthquakes, indicating that the earthquakes affected the slope wall. The results provide evidence that the microseismic tech¬nique is applicable to large pit walls, and that the wide band, wide range microseismic equipment appears to be suitable for open-pit investigations.

Jan 1, 1969

By F. Khorram

Image processing is a technique that simulates the human vision system. This technique enables applying every statistical or intelligent operation to recognize differences. In this way this new technique is used in quality control systems in most industries. Studying sedimentary rocks is very important from the economic point of view. Some units of sedimentary sequences involve different mineral deposits, hydrocarbon and water resources. Therefore it is important to identify and classify different sedimentary rocks. Descriptive classification of sedimentary rocks is usually based on visual and textural features and chemical composition of a sample. In this paper different samples of a limestone mine in central part of Iran are classified. The samples were collected from different parts of the mine and crushed down in size from 2.58 cm to 3.58 cm. The rock samples were labeled based on percentage of chemical and lithological compositions. Each sample was assigned to one of the distinguished groups. The images of the samples were taken in appropriate environment and processed. A total of 74 features were extracted from the identified rock samples in all images. In order to feature dimensional decrease, principal component analysis method was used. Then Bayesian statistical algorithm was used as a useful tool for classification. Classification Correctness Rate (CCR), calculated for the test data sets are %88, %68, %61 and %72 for the first to fourth class respectively. Therefore it can be inferred that the extracted features of images are appropriate indicators for different samples identification. These precise results besides the advantages of image processing technique, which are increasing speed of operation and decreasing cost, appears to be a desirable success.

Jan 1, 2012

By Vernon N. Cox

From comments and questions concerning the meaning of USNR, and "why is the Navy in the mining business?" I believe it is worth while to establish the background and purpose of our company. We are a stock company formed by the purchase and reorganization of a company known as the U. S. Natural Gas Corporation. In May 1969, a group of investors with Mr. Robert L. Katz as president and chief executive officer, created United States Natural Resources, Inc., to develop and purposively use our Natural Resources in four areas: 1. Mines and Minerals 2. Forest Products 3. oil and Gas 4. Recreational Lands As final proof that we are not a government organization, I simply state. "We pay taxes." The mining division was formed in October 1969, with the completion of the merger of USNR and Vibration Measurement Engineers, Inc., Of Evanston, Illinois. Throughout the industry we were known as "VME," our company supplied consulting service in the field of seismic energy control, mining consulting and. we operated drilling, blasting and, contracting organizations in several areas of the country. Since that time we have developed and acquired producing properties in Quarrying, Coal Mining and Cement Copper Production.

Jan 1, 1971

By Daniel de la Rosa, Juan Manuel Mayoral, Damián Vital

"This paper presents a numerical study regarding the loads, and the corresponding damage, taken by the primary and secondary lining of a tunnel built in cemented fine-grained stiff soils. This study aims at establishing more rational design criteria that take into account explicity the lining performance. A 3.5 km long tunnel to be built in a densely populated northwest area of Mexico City, was considered as case study. Series of three-dimensional finite difference models, developed with FLAC3D, were used to simulate the tunnel construction, and to compute the ground settlements, internal forces, bending moments, and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams were used to study the lining performance. Several advancement lengths, and tunnel covers were considered to establish their impact on the loads transferred to the tunnel lining. A practice-oriented damage criterion for tunnels was proposed based on the interaction diagram analysis. INTRODUCTION Lining performance during conventional tunnelling, CT, as defined by the International Tunnel Association, ITA (ITA 2009) is strongly affected by the construction procedure. Special attention must be taken in cemented fine-grained materials, such as those found in the northeast portion of Mexico City, due to the potential of fragile failure (i.e. the soil fails suddenly without important deformation) that these soils may exhibit. During CT, it is assumed that the ground strength contributes to the stability of the excavation, as long as the lining is built correctly. It is common practice to consider two structures, which together form the tunnel support: 1) A primary lining, which is a flexible support, which allows excavation walls to deform to mobilize part of its shear strength, and thus contributes to the tunnel self-stability, and 2) A secondary lining. Commonly, the primary lining consists of several layers of shotcrete. In this case the installation method guarantees perfect contact between the lining and the excavation perimeter. The secondary lining, if required, is used to withstand the load conditions in the long term and also has an esthetic function. This paper presents a numerical study aimed at establishing a performance damage criterion for the primary and secondary lining design in cemented fine-grained stiff soils. Due to the lack of data, the strength and deformation parameters were established through empirically-derived relationships. Three-dimensional finite difference models were developed to simulate the tunnel construction, and compute ground settlements, internal forces, bending moments and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams, along with a damage criterion were used to study the lining performance. From the results gathered insight was gained regarding tunnel lining performance during CT."

Jan 1, 2016

By V. L. Ketellapper

This paper discusses the technical issues and stakeholder collaborative processes which resulted in achieving a balance between the reclamation of abandoned mine sites, providing affordable housing, and preservation of open space at the French Gulch Site. Through this process, it was discovered that mine site reclamation would need to be conducted in conjunction with two priorities for community sustainable development: providing affordable housing for locals who work in the resort town of Breckenridge, and open space preservation. It was found that conducting these activities concurrently would result in providing resources necessary to complete mine site reclamation. The first phase of the affordable housing development is almost completed. This development resulted in redevelopment of mining impacted lands and was recognized by the U.S. Environmental Protection Agency (EPA) with a National Smart Growth Award in 2002.Negotiations are also underway to preserve the remaining 1,800 acres of land held by the mining company as open space. This transaction will in turn provide resources to address water quality issues associated with mine discharges.

Jan 1, 2004

By John Hardy

The performance of five dense-medium washers was evaluated in four preparation plants. Three of the plants were making a two-product separation that produced a clean coal and a refuse; one plant employed dense-medium vessels in series to effect a primary and a secondary separation. The secondary drum-type washer produced a low-ash metallurgical coal and an intermediate-ash product suitable for plant fuel or steam generation. The sharpness-of-separation was excellent for all four primary separations and the secondary separation.

Jan 1, 1966

By David M. Jurich, Randy J. Essex, Alex de Aboitiz

An Automated People Mover (APM) transit system is planned for the growing Phoenix Sky Harbor International Airport. The APM will improve passenger movements between the terminals, and provide a link to parking facilities, a new rental car facility, and the planned metro Light Rail. The underground works will include shallow twin bored tunnels, taxiway crossings, and underground stations constructed beneath critical airport facilities. Challenging soft ground conditions will require extensive underpinning and ground improvements. Design is underway, and construction is scheduled to begin in 2007 with project completion in 2015. The owner’s planned delivery method for the APM Project will be Construction Manager at Risk (CMAR) with a Guaranteed Maximum Price.

Jan 1, 2005

By Georgene Renner, William R. Yernberg, Steve Kral

ABB offers complete electrical revamps of mining shovels with ac or dc drives, drive control, frequency converters with insular gate bi-polar transistor technology, intelligent control packages and visualization. Many of the world’s shovel excavators and draglines (walking excavators) were built in the1980s. After 15 to 20 years of round-the clock operation in openpit mines, these machines start to feel their age. Electrical parts are particularly vulnerable. Their performance deteriorates and availability and productivity fall. Even with regular ser-vice and maintenance, a machine of this age will accumulate 400 hours of unscheduled downtime a year. The need for a replacement becomes pressing, but the expense is often prohibitive.

Jan 1, 2005

By E. J. Jacques

A typical problem in ventilation networks with multiple fan systems is the possibility of them interacting. Multiple fan systems are no exceptions in complex tunnels, and may also be met in mines where underground fans are installed. When aiming at controlling a multiple fan system in a ventilation network, e.g. with a view to maintaining an acceptable air quality level, yet at minimum power consumption, transient flow conditions frequently occur. Although in most applications these transients are short compared to the time needed to achieve the planned actions on the ventilation, one should, however, keep in mind that it is important to avoid any bouncing effect between different (adjacent or distant) fan systems. Therefore a simulation of the unsteady-state flows could allow us to learn more about the propagation of transients within the network, and their possible secondary effects Among others, one question that often is raised, is to find out in which sequence and at what time schedule each of the fans in a network should e.g. be started up? Another typical problem, into which an unsteady-state simulation could provide some insight is the following: how should the facilities of variable pitch angle and/or changeable RPM of several fans operating in parallel be handled and combined in order to obtain a flow rate that changes gradually from zero to its maximum value i.e. the sum of the individual throughput flows of all the fans. The literature is not very abundant on the topic of simulating transient flows in networks. There is no doubt that numerical models have been developed (Pollak, Christensen, 1987), most of the time for particular applications (Wala, Kim, 1985), (Tanaskovic et al., 1984), (Schultz, Sockel, 1991), etc. The aim of this paper is to present a model that also simulates one-dimensional compressible flows in unsteady-state conditions with, however, the specific intent to handle networks with more than one fan. PROBLEM STATEMENT The mathematical model chosen to describe the unsteady flows in a ventilation network is based on the dynamic and continuity equations applied to each of its airways. The following basic assumptions are made : - the flow in the airway is considered to be one- dimensional, - - the flow is assumed to be fully turbulent, and hence the ATKINSON equation for calculating the friction losses will be applied. Whether this equation remains valid for transient state flows remains an open question. However, this may reasonably be assumed since the interesting flow frequencies are low. A discussion may be found in (Kämpf, 1987) ; - the airways are assumed to have a constant cross- sectional area along their length. If obviously this would not be the case, it is always possible to subdivide the concerned airway into sections for which the previous assumption holds. Applying the basic equations of mass and energy conservation, the flow in each branch may be described by the Euler equation for Newtonian flows.

Jan 1, 1995

By James D. Bennett

Relationships among mine and injured miner characteristics and HSAC's degrees of injury are examined for 91,404 injuries in under- ground bituminous coal mines in the United States from 1975 through 1982. Injury severity varies by the mining system, geographical region, circumstances surrounding the injury, the injured miner's age, whether the miner was using powered equipment, the year which the injury occurred, and the location in the mine where the injury happened. Injury severity is not related to the injured miner's total mining experience, job experience, and experience in the mine in which the injury occurred.

Jan 1, 1984

By J. M. Mutmansky, Y. J. Wang

The method usually used to predict the direction of flow in a connecting airway is to conduct a survey of the two existing nodes to be connected by the new pressure airway. It is then assumed that the air will flow from the node with the measured higher pressure to the node with measured lower pressure. This paper examines this direction-of-flow problem using properties of the system characteristic curve for a two-terminal network and specifies some conditions that will ensure that the air will flow in the direction anticipated. It was concluded that the only requirement is that all characteristic curves of the fans in the network should be strictly decreasing. Five numerical examples illustrate some important proper- ties of the direction-of-flow problem.

Jan 1, 2000

By Bruno A. Fichna

Longwall mining offers low cost potential for coal with high capital investment. As opposed to two shifts-per-day operation in most long- walls, Saarberg Mines in Germany increase utilization of capital by operating their longwalls around the clock. Differentiation between capital and operating costs, corrective maintenance versus preventive maintenance, improved roof conditions, and economical life of equipment was investigated. A surprisingly high degree of improvement was attained. Capital costs at Saarberg longwall coal mines have been reduced through a step-by-step research and trial program. This reduction was particularly influenced by the high performance pilot longwalls at the Ensdorf mine. The following presentation shows data and figures of those longwalls. End results were 40% reduction in capital costs, which could contribute favorably to investment decisions in the coal industry in a supply side economics environment.

Jan 1, 1982

By Pawan Bharadwaj, Wim Mulder, Thomas Tscharner, Guy Drijkoningen, Rob Jenneskens

"The Earth’s properties, composition and structure ahead of a tunnel boring machine (TBM) should be mapped for hazard assessment during excavation. We study the use of seismic-exploration techniques for this purpose. We focus on a seismic system for soft soils, where shear waves are better and easier to interpret than compressional waves, as has been shown over the last decade. The system is intended to be deployed on the machine’s cutter head, with a few seismic sources and sufficiently many seismic sensors to tackle spatial variability and noise characteristics. An important property of the newly developed system is its ability to process data with very little human interaction. Images need to be available in near real time, without human interactions slowing down the imaging process. This can be achieved by employing Full Waveform Inversion, which minimizes the difference between modeled and observed data. Because this method may suffer from local minima in the cost function if the data lack low-frequency information, we employ a dedicated seismic source that can generate sufficiently low frequencies for the relevant length scales. With data acquired in a number of field settings that mimic realistic TBM configurations, we show that the designed seismic system can successfully look ahead of the TBM and offers a valuable capability to support decision-making during tunnel excavation. INTRODUCTION While excavating a tunnel with a Tunnel Boring Machine (TBM), the geology and the ground conditions along the planned tunnel trajectory need to be investigated in order to safely and efficiently carry out the underground operations. This entails detecting the occurrence of boulders, foundations, pipes and faults, necessary to prevent hazards and time-consuming delays in the tunnel boring operations. In order to facilitate ground prediction ahead of a TBM, techniques as used in seismic exploration can be deployed. Two components common to seismic-exploration techniques are data acquisition and processing, the latter including inversion. We will discuss each of these for the application to tunnel excavation with TBM, in particular for soft soils."

Jan 1, 2016

By J. H. White

It is hypothesized that the Hotelling valuation principle (HVP) can determine the value of developed gold reserves using simple methods and easily obtainable data. This paper reports the results of an empirical test of this hypothesis. The model for the HVP is given by [V R=Cp-0(1) or V - CP-0' R(2)] where p = current spot price of gold per oz, [c] = average extraction cost of gold per oz, V = current market value of the gold in the ground (dollars) and R = gold reserves (oz). Using publicly available data from North American gold companies, we obtained data for V, R, p and c, and we ran a simple linear regression using Eq. (1) as the definition of the dependent and explanatory variables. By examining the value of the coefficients of the resulting regression equation, we can draw conclusions as to whether or not the HVP can be confidently used as an estimator of the value of developed gold reserves.

Jan 1, 1997

By Valerie (Wollet) Rebar

Successful execution of fast-track projects is an arduous task at best. Effective and organized management, a comprehensive technical design with an independent check-and-balance system, and optimal schedule components all play major roles in project success, regardless of the required timeline. However, a fast-track schedule intensifies the significance of each of these elements due to the heightened time constraints.

Jan 1, 2008

By Allan J. Breitenbach

The heap leaching process has developed into a low-cost method for recovering copper, gold and silver from large and small deposits of low-grade ore. The earliest known heap leaching process with chemicals occurred in about 1752 and is attributed to Spanish miners percolating acid solutions through large heaps of oxide copper ore on the banks of the Rio Tinto (Ran Zyl, et al., 1988). In 1969, US Bureau of Mines research¬ers proposed the use of dilute alkaline cyanide solutions as a low-cost means for recovering gold values from low-grade ore containing micrometer-sized particles of gold (Miners News, 1991). The modern-day heap leaching process typically involves the percolation of leach solutions through controlled lifts of stacked, low-grade ore (crushed, aggomerated or run-of-mine) in a heap for chemical extraction of precious and base metals into solution (Fig. 1). The enriched (pregnant) solution is collected by gravity flow in lined basins, sumps and ponds for processing and recovery of the target metals (copper, gold and silver). The barren solution from the recovery facilities is recirculated to the heap, along with chemical reagents and makeup water, for containment of all process solutions in an enclosed and environmentally sound system. This involves the use of low-permeability liner systems beneath the heap leach stacks to maximize solution recovery and protect the underlying ground water (Fig. 1). This article discusses the typical heap leach liner systems currently used by mining companies in North America. The most successful heap leach pad liner systems from past precious metal operations generally include an underlying, low-permeability soil bedding material; a geomembrane liner, and an overlying protective cover fill.

Jan 1, 1994

By Frank J. Markewicz

The expanding: demand for ilmenite for use in the manufacture of titanium pigments, the knowledge that much of this raw material comes from distant points and therefore has to include a heavy freight charge in the price of the delivered product, and the further knowledge that ilmenite occurs both in the crystalline rocks of northern New Jersey and also in some of the Triassic igneous rocks, were considerations which led to a search for ilmenite-bearing sands in southern New Jersey. That this search was successful is now history, and it is the senior author's privilege to state here that most of the credit belongs to his associates who did all of the heavy work of hand-augering for samples, and who made all of the heavy-mineral separations. We all are grateful to members of the Department of Geology at Rutgers and Princeton Universities for the use of equipment which enabled us to evaluate certain samples from our ilmenite exploration program. In addition, we wish to express our appreciation to many companies for their cooperation and for their permission to publish mineral and chemical analyses. We also acknowledge with much appreciation our debt to the geologists and engineers with whom we have had many lively and rewarding discussions relative to the ilmenite deposits.

Jan 1, 1958

By Ted C. Mathews

Pre-concentration by sorting is as old as the mining industry. Inevitably waste rock is broken with ore. Separation may take place in the stopes by selective mucking and transport, or selective loading and transport of ore and waste by 12-cu, yd. shovels and 100-ton trucks in large open pit operations. Hand sorting of 1" to 16" pieces, formerly widely practiced at underground chutes and prior to or following first stage crushing, has greatly diminished in the United States with its high per hour labor cost, although still widely practiced in other countries and, surprisingly, in some of the most modern mills where inexpensive labor is available. The economics of pre-concentration by sorting is attractive since elimination of waste at any cost less than the total milling cost will show a profit. The size at which sorting should be under- taken is determined by the size at which liberation is secured to yield a product of ore and waste, and greatly influences cost and the point in the flowsheet where sorting can be undertaken. In some instances mining costs can be reduced where an inexpensive sorting system to eliminate waste is combined with a less selective and less costly mining method. This is particularly true in deep mines where hoisting capacity determines the rate of extraction and sorting is performed underground, with waste utilized for fill. Hand sorting, while efficient, is expensive because of low sorting rates. Peale (1) quotes man hour capacity at 1/3 ton per hour on sizes 3/4" to 3" copper ore, and up to 5 tons per hour on rich iron ore sized from 4" to 16".

Jan 1, 1974

By Y. J. Wang

The definitions of system pressure loss (mine head) and system resistance, which are traditionally associated with single-fan net- works, are applied to multiple-fan ventilation networks. The system characteristics -- relations among air power, pressure loss, air quantity and resistance -- are analyzed by introducing the concept of subsystems. These subsystems are associated with the fans located in a cutset of the network. For a multiple-fan network, the resistances for the subsystems and total system are dependent on the quantity ratios of the subsystems. In general the pressure loss of a subsystem or a total system does not vary as the square of the corresponding air quantity. If the quantity ratios of subsystems are all held constant, then the resistances become constant and the pressure losses are predictable from the quantities employing the "square law." The system resistance has a minimum value under the natural- splitting flow pattern. Being independent of the value of system quantity, the minimum system resistance provides a basis for comparing the different networks.

Jan 1, 1983