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By Ben L. Seegmiller

Localized open pit slope failure was avoided as an apparent result of a practical rock mechanics program conducted at the Twin Buttes copper operation. The key to the program was the application of cable bolting, a technique that artificially supports open pit slopes using properly installed post-tensioned cables. As a result of the research and testing program, extensions of the cable bolting principal became significantly apparent. • The economics of artificial stabilization appear to be overwhelmingly favorable, and • Best practical applications are "final" pit slopes, slopes beneath permanent structures and potentially slope failing areas. Success of this research is manifested by the fact that similar stabilization systems are presently under consideration for Twin Buttes as well as other open pit operations.

Jan 12, 1974

By Earl A. Gulbransen, Kenneth F. Andrew

DRY oxidation of zirconium has been studied by several groups.'" The present work extends our early study1 to the high-temperature studies of Cubicciotti2 and Belle and Mallett.8 ulbransen and Andrew1 showed that the parabolic rate law fitted the 2-hr experiments between 200" and 425°C after an initial deviation. An energy of activation of 18,200 cal per mol was calculated. Cubicciotti,' in a study between 593" and 880°C, showed that the parabolic rate law fitted the data and an energy of activation of 32,000 cal per mol was calculated. In contrast to these studies on sheet specimens, Belle and Mallett3 studied the oxidation reaction on rod specimens and found a cubic rate law to fit the data.

Jan 1, 1958

By G. J. Armstrong, K. S. Lynch, C. G. Thomas, L. A. Baker, R. J. Cornelius

The presence of geothite in a hematite ore has been shown to strongly affect the time of heating to the firing temperature. The investigation of spalling of single pellets and of packed beds has enabled free water and goethite spalling to be identified as separate phenomena. In addition, it has been shown that even for an 18-in. deep bed of green balls, the free water and goethite drying periods can be considered separately. Based on this observation, a method of predicting production rate and hood temperature profile is presented. The method required knowledge of the ore goethite content, ore grind, and the green pellet bulk density. Laboratory results were found to be in good agreement with actual plant practice and have led to improved process performance.

Jan 1, 1974

By James G. Stuart, Tassilo N. Baur

We will discuss the kind of procedure that we use to predict the no-fire (for safety) and all-fire (for reliability) current levels for any given type electric detonator. The basic idea is to expose several detonators to different levels of electric current, so we can estimate the probability of firing as a function of current. We call this a statistical firing test. But what about the uncertainty in measuring the current? Suppose we are not quite sure what stimulus level we apply? This is the question that we will consider here. This relates to both safety and reliability. Surprisingly enough, we will find that some uncertainty in measuring the levels during our statistical firing test improves our long-term safety and reliability

Jan 1, 2019

By Dal Sun Kim, Michael K. McCarter

"Comminution (crushing and grinding) of rock materials is energy-intensive and expensive. Mucheffort has been directed to improve the efficiency of conventional milling practice, but relatively littleattention has been given to the potential benefits of blast-induced damage on comminution processes. To help assess this effect, research has been conducted at the IRECO Laboratory and the Generic Center for Comminution at the University of Utah. The objective of this research is to investigate the effect of shockinduced “crack-like” damage on rock properties and subsequent breakage efficiency for three petrologically different rock materials under laboratory conditions. In order to evaluate the effect of shockinduced damage, a quantitative measure of rock damage is needed. For this purpose, a scalar variable (0) is proposed."

Jan 1, 1993

By J. E. Meacham

The U.S. Bureau of Mines investigated recovery of manganese from basic oxygen furnace (BOF) steelmaking slags because the slags represent a large potential resource of a metal for which there is no domestic production. BOF slags were leached using fluosilicic acid, a byproduct of the fertilizer industry. Manganese and iron were extracted as soluble manganous and ferrous fluosilicates while the calcium and magnesium remained in the tailings as insoluble fluorides. Treating the pregnant liquor with sodium chloride, precipitated sodium fluosilicate (Na2Sif6) which was recovered as a byproduct. Manganese and iron were precipitated as hydroxide-carbonate salts with the addition of sodium carbonate to the treated liquor. Recoveries for manganese and iron were 73 to 83 and 67 to 70 pet, respectively.

Jan 1, 1991

By Kim Lapakko

As part of a project funded by the US EPA, through the Western Governors' Association, the recent literature on the prediction of acid drainage from metal mine wastes was reviewed. Static tests such as Acid Base Accounting, Modified Acid Base Accounting, B. C. Research Initial Test, and APP:S Test attempt to quantify the total capacities for a mine waste to produce and consume acid. In kinetic tests (e.g. humidity cells, soxhlet extraction, elevated temperature oxidation, column tests, batch reactor tests, B. C. Research Confirmation Test) mine waste samples are subjected to oxidation and the resultant drainage pH is assumed to reflect that of mine wastes dissolving in the field. This paper summarizes information presented in the recent literature on static tests.

Jan 1, 1992

By Howard L. Hartman

The past 15 years have seen rapid advances in the metallurgy of materials for drill machinery and bits, but rock drilling itself continues to be largely an art. Jet piercing, roller bit rotary drilling, and rotary percussion are all promising new techniques, but the percussion rock drill, still used for 90 pct of the blastholes in U. S. hard-rock mining, has under- gone no major modification since pneumatic machines were first used successfully in the 1860's. This singular lack of progress stems directly from ignorance of the nature of impact failure of rock and the fundamentals of rock penetration in general. For nearly three-quarters of a century, mining engineers did not know what went on at the bottom of a drillhole.

Jan 1, 1959

The North American Coal Corp. Increasing demand for coal, stimulated by the national energy shortage, and complicating and often conflicting, demands by government and ecology groups for better land reclamation methods continued to propel advances in surface mining technology during 1974. To meet current demands for coal (estimated at more than 700 million t for 1975 and 1.5 billion t in 19851, equipment manufacturers and coal operators concentrated on increasing the productivity of all surface mining equipment. The trend towards larger equipment, particularly in overburden removal, loading, and haulage machinery, prevailed during the year, notwithstanding the perennial debate over the economics and practicality of using large, inflexible equipment. Increasingly, the industry called on computers to monitor productivity and help design more efficient production systems

Jan 2, 1975

By K. K. S. Ho

In Hong Kong the design of excavated piles in weathered granite has conventionally been based on a rule-of-thumb which relates the allowable base bearing capacity to the SPT N value, with no allowance for skin friction. This rule-of-thumb has been shown to generally lead to conservative designs. To improve the overall understanding of load-transfer mechanism of excavated piles in weathered granite, instrumented pile load tests have been conducted. This paper summarises a selection of instrumented pile load test data in Hong Kong and the observations made of the results, which indicate that there was considerable scatter in the back-calculated skin friction values. However, the mobilized skin friction was shown to be significant which can lead to substantial savings in design.

Jan 1, 1996

By I. E. Rosenzweig

The problem considered in this paper is as follows: An arbitrary horizontally stratified area is given. The electrical properties of this area are characterized by a function p(z) (Fig. I), which shows the relationship between resistivity p of the soil and the depth z. For such general case the apparent resistivity p* will be computed, by earth-resistivity measurements carried out by any given configuration of electrodes. General solutions of this problem appear to be very important for interpretation of field results of resistivity measurements, concerning structural investigations. Such solutions have been given by many authors for the special case of a finite number of homogeneous layers (Fig. 2)lV4 as well as for the more general case of continuously ranging resistivities.5-8

Jan 1, 1940

By C. V. O. Hughes

Florida phosphate operations are unique in the ways standard mining equipment is made to meet specialized problems. Hydraulic mining and transportation has evolved in meeting three such special problems: 1) surface mining of a shallow, poorly consolidated but wet material; 2) high pro¬duction rates, necessary because of low prices for phosphate rock in a highly competitive market; and 3) preparation of the value-bearing rock, or matrix, for washing and flotation. The magnitude of the problems is better appreciated if the reader understands the size of operations in the area. The Florida phosphate field produces and ships about 10 million tons per year of phosphate rock. All of this has to be concentrated to its shipping grade, either by scrubbing and screening or by flotation.

Jan 1, 1956

By I. E. Rosenzweig

The problem considered in this paper is as follows: An arbitrary horizontally stratified area is given. The electrical properties of this area are characterized by a function p(z) (Fig. I), which shows the relationship between resistivity p of the soil and the depth z. For such general case the apparent resistivity p* will be computed, by earth-resistivity measurements carried out by any given configuration of electrodes. General solutions of this problem appear to be very important for interpretation of field results of resistivity measurements, concerning structural investigations. Such solutions have been given by many authors for the special case of a finite number of homogeneous layers (Fig. 2)lV4 as well as for the more general case of continuously ranging resistivities.5-8

Jan 1, 1940

By M. C. Roberts

Metal producers are now suffering through a major downturn in prices for their products even though it has only been a few years since they were enjoying high prices. From an historical perspective, the current situation is another of the cyclical downturns that often occur every five to seven years. This paper uses time-trend decomposition techniques to identify the cycles and statistical methods to find the duration of these cycles for a variety of metal prices. Given some idea of how long and severe these cycles typically are, the mining industry can better plan to weather the downturns and take advantage of the upturns. For example, timing investments in new projects to take advantage of the cyclical upturns can dramatically improve project profitability.

Jan 1, 2003

By H. B. Carroll

The Bureau of Mines investigated the adaptability of the Meteorology Research Inc.2 (MRI) nephelometer and the Sinclair-Phoenix smoke meter for use in routine, analytical, smog-chamber experiments and to compare their responses to aerosol during these experiments. Both instruments' sampling systems were modified--smaller size sample input systems were studied using the nephelometer and a secondary sample system was added to the smoke meter to allow measurement of Aitken or condensate nuclei. Both instruments were easily adapted for use with small smog chambers and both displayed good precision and sensitivity to aerosol. A correlation was shown to exist between the two instruments' responses to aerosol. This correlation makes it possible to report the Sinclair-Phoenix measurements in visibility and/or mass units if desired.

Jan 1, 1973

By Robert L. Crosby

The Bureau of Mines investigated the substitution of cement copper powder for commercial copper powder in an Fe-7 pct Cu-l pct C powder metallurgy alloy. Copper powders from six different commercial cementation operations were separately upgraded by screening and hydrogen reduction. They were then mixed with commercial iron and graphite powders to form the Fe-7 pct Cu-l pct C alloy. Various chemical and physical properties were determined on the upgraded cement copper and the alloy powders. Mechanical, physical, and chemical properties were determined on green and sintered specimens made from the alloy powders. Mean tensile and bending strength of sintered specimens were significantly lower than the means from specimens made from commercial metal powders. The lower strengths are apparently related to poor sinterability.

Jan 1, 1970

By W. Chubb

FOR the past several years there has been considerable interest in the development of zirconium and zirconium alloys for application in nuclear reactors. In a portion of the development work being conducted, attention has been given to the development of high-strength zirconium alloys. One of the most outstanding alloys developed in the course of this work is Zr-4 wt pct Sn-1.6 wt pct Mo.' Fabrication and Test Methods Over 50 ingots of zirconium containing either tin and molybdenum or both have been evaluated in the process of selection of an optimum composition. Most of these were prepared as 20-g are-melted buttons; a few were prepared by induction melting. All ingots were prepared by the me of Foote Mineral

Jan 1, 1958

Geological modelling is a crucial preparatory stage to most facets of the mine planning of an orebody. The process of modelling involves skilled geological interpretation. Recent innovations in computer software and graphics hardware provide many tools which can be used to dramatically improve on manual methods of interpreting orebody data. Geological interpretation can be carried out quickly to produce accurate block models for many orebody attributes, such as grades, and these models can be easily updated locally as exploration and mine development data become available. The speed of the modelling process coupled with the mass storage capabilities of the computer now allows geologists to optimise the geological model or carry more than one model through to the mine planning phase.

Jan 1, 1987

By L. Shwydiuk, A. Chrzanowski, W. Newcomen, G. Bastin, R. Wilkins

Automated monitoring of steep embankments allows the early detection of instability and can be used to avoid or mitigate possible slope failures. A system that uses multiple and different types of sensors has been created and successfully tested at the Highland Valley Copper mine in British Columbia. The system uses robotic total stations (RTSs) as the primary measurement sensor, with surveys repeated at predefined intervals selected to optimize operational efficiency. A methodology has been developed to improve the system’s accuracy and reliability by reducing the effects of systematic errors created by atmospheric refraction and unstable instrument and reference point positions. The inclusion of GPS sensors to monitor the RTS positions creates additional operational flexibility and maintains system integrity when insufficient reference stations are available.

Jan 1, 2003

By Janet Torma-Krajewski, Pauline Lewis, Paul Gust, Lisa Steiner, Kean Johnson

Since 1990 and the publication of the Ergonomics Program Management Guidelines for Meatpacking Plants by the US Occupational Safety and Health Administration, numerous reports of companies implementing ergonomics program have been published. However, despite these numerous reports, no examples of implementing an ergonomics program in the mining industry have been reported. In 2000, NIOSH initiated a long-term project to demonstrate the implementation of an ergonomics process designed to identify and reduce exposures to ergonomic risk factors found in mining. The mine selected for this project was the Jim Bridger Mine, a surface coal mine located 35 miles northeast of Rock Springs, Sweetwater County, WY. This paper discusses how a large, surface coal mine implemented an ergonomics program and the lessons learned while doing so.