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By A. Ersoy, M. D. Waller

Because of a shortage of diamonds for the drilling industry in the 1970s, efforts were made to develop synthetic diamonds. The resulting development of polycrystalline diamond compacts (PDC) enabled the evolution of a new generation of rotary-drilling drag bits. Bits based on PDC cutters were very successful in drilling soft, abrasive and medium strength rocks. However, because of their thermal instability, they failed rapidly when drilling hard rocks. Thermally stable diamond (TSD) was then developed for hard-rock drilling. The rate of penetration (ROP) and bit life significantly influence the drilling cost. The ROP and the life of the TSD bits or cutters are affected by a number of complex factors. However, in laboratory testing and infield operations, the principal factors that need to be considered in predicting drilling and wear rates are bit design characteristics, bit operating parameters and the characteristics of the penetrated rock. These characteristics are comprehensively reviewed for both laboratory and field drilling results using TSD bits. Optimization of these parameters increases the drilling rate, prolongs the bit life and reduces the drilling cost.

Jan 1, 1998

By R. M. Geisenheyner

We are in the midst of a transportation revolution. From the Wright Brothers to the SST. From the Toonerville Trolly to the 120-mile-an-hour Northeast Corridor train. From Christopher Columbus to Neil Armstrong. There is another side to this revolution and it is going on every day at our mines and factories. We call it bulk distribution. Perhaps ordinary sounding, but every bit as exciting as those other transportation innovations. Basically, we have gone from bag to bulk, and in the process reached that Last Frontier in manufacturing cost savings. By revitalization of our distribution system, we have made it possible for our mines and factories to realize fully the vast economies of spage-age manufacturing techniques and accomplishments. The pacesetters in this distribution revolution have been you gentlemen, the producers and shippers of dry mineral products. In this area bulk distribution grew up. And here most of the current innovations are being introduced. Management of your industry was early to realize the economic advantages of bulk distribution. Distribution costs of your products comprises a sizeable, portion of the selling price and management is sensitive of any developments which may even slightly reduce the cost of transportation, marketing or the exploration of new frontiers.

Jan 1, 1969

By D. Royston

The use of large face angle shell lifter-liners in combination with wider lifter spacing has grown in recent years, especially in large SAG mills. The claimed benefits are reduced ball on liner impact, leading to increased liner lives and less ball breakage, and both reduced packing and improved ball-on-charge impact, leading to improved mill performance. This review covers available published data on several mill sites and aims to quantify the observed benefits.

Jan 1, 2003

By G. R. Laurer, J. W. Neton, C. Pomroy, N. Cohen, M. Eisenbud

INTRODUCTION In uranium miners, a causal relationship between exposure of the lung to high levels of alpha radiation and the consequential induction of bronchial carcinoma is now well-established (Wagoner, et al., 1965). Quantitation of this cause-effect association presents considerable difficulty, however, as the result of various confounding factors such as the contributing effects of smoking and/or arsenic exposure (Archer, Gillam, and Wagoner, 1976), normal metabolic variability and, perhaps most important of all, the absence of accurate radon/radon daughter exposure data. Estimates of cumulative lung exposures suffer from inaccuracy due to critical factors such as 1) unknown ventilation rates; 2) difficulties in obtaining representative mine air samples; 3) the variable character and magnitudes of the exposure sources; and 4) specific differences in metabolism and job histories that exist among miners. It was with considerable enthusiasm, therefore, that investigators readily embraced the idea of using skeletal burdens of the relatively longlived descendants of radon and its short-lived daughters, i.e., 210 Pb and 210Po (Archer, et al., 1968), to provide a measure of cumulative past exposure wherein the body acts as an integrating dosimeter. Early studies considered excretion rates of 210Pb and 210Po in urine, blood and hair (Sultzer and Hursh, 1954; Black, et al., 1968; Jaworowski, 1965; Bell and Gilliland, 1964) as well as their concentrations in bone samples, if and when they became available (Blanchard, Archer, and Saccomanno, 1969). These methods were ultimately complemented by in vivo, whole-body counting techniques using low background, NaI-Csl(T1) detectors (Eisenbud, et al., 1969). By this latter method, it would be possible to measure the skeletal burden of 210Pb directly, thereby avoiding the many difficulties associated with the relation between nuclide excretion rates and body burden. The rationale was simple; by knowing the skeletal burden of 210Pb it should be possible, by the judicious use of an applicable metabolic model, to estimate the cumulative lung exposure to alpha-emitting radon daughters (Fig. 1). Various models that were consequently constructed, however (Fisher, 1969), all suffered from the same limitation, i.e., the assumption that the source of 210 Pb in the skeleton and the source of lung exposure to the short-lived radon daughters were simply related and, if not, were at [ ] least not too variable (Raabe, 1970). By now, the difficulty with this assumption has been recognized and more sophisticated modeling techniques have been attempted which presumably present a more realistic picture of exposure conditions (Holtzman and Rundo, 1981). There is, nevertheless, the pessimistic view that due to the variety and variability (in time as well as in character) of sources that may exist for the origin of 210Pb in bone, it may [never] be possible to estimate past lung exposures accurately by an indirect, predictive model. For example, the origin of 210 Pb in the skeleton may include such sources as: 1) the decay of short-lived 222Rn daughters, inhaled and ingested; 2) the decay of 222Rn dissolved in body fluids and tissues; 3) directly from 210 Pb present in air, inhaled and ingested; and 4) 210Pb from non-occupational sources, e.g., food, water, smoking and endogenous 226Ra. The contribution of each of these sources may vary depending upon specific site conditions such as ventilation and mining operation. On the other hand, empirical evidence seems to indicate a trend reflecting the simplest of direct

Jan 1, 1981

By VIVEK KUMAR HIMANSHU, PK SINGH, AK MISHRA, MP ROY, RAVI SHANKAR

Underground blasting has many challenges. The primary aim of blast designers is to optimize drilling and blasting parameters to deal with the associated challenges. Optimizing these parameters is currently based on various rules of thumb, which have many site-specific limitations. Accordingly, computation of these parameters using empirical rock fragmentation predictors can be useful for blast designers. This paper presents the results of work on burden-spacing determination by back-calculation from the empirical Kuz-Ram model for underground stope ring blasting.

By Bobby G. Wixson

The computer aided mapping of lead concentrations in soil has been carried out around the Doe Run (formerly AMAX-Homestake Lead Toilers) primary lead smelter near Boss, Missouri, through a cooperative Missouri Research Assistance Act program between the lead industry and the University of Missouri. As a part of this research a sequential extraction method was also developed to analyze and determine the various species of lead in the vicinity of the smelter as to possible sources which would suggest pertinent environmental control measures. Practical applications of this data-based scientific approach will be presented.

Jan 1, 1988

By A. Bruce Waugh, W. W. Wen, Kevin N. Clark, Neville C. Lockhart, Bruce A. Firth

Australia is the world's largest coal exporter, and technological advancement is a key element of the coal industry strategy. The issues include: increased recovery of saleable coal; enhanced quality, i.e. lower ash, moisture, fines, phosphorus (sulphur is a relatively minor problem for Australian coals); better quality control; higher throughputs/lower costs; improved handling and transport; and reduced environmental impacts. In process terms, many coal preparation operations, particularly fine coal circuits, are relatively inefficient, and all circuits must also be matched and integrated for optimum overall operation. A holistic approach to technological improvement is desirable. This paper summarises research and development efforts, within CSIRO and its collaborators, across the unit operations as outlined in the title.

Jan 1, 1995

By Philip-Mark Spanidis, Christos Roumpos, Francis Pavloudakis

This paper presents a quantitative research (QNR) methodology, collaboratively conducted with a group of mining experts, to assess the knowledge management (KM) landscape in the Greek mining industry. The methodology involves a framework for structured data collection using questionnaires, statistical analysis, discussion on critical methodological aspects, and interpretation of results focusing on key aspects of interest for designers of KM systems. The paper concludes by summarizing the methodology’s outcome and proposing perspectives for further research.

Aug 1, 2024

By Michael Cruickshank

All life on Earth relies on the ocean and yet the ocean is 95 percent unexplored, unknown and unseen by human eyes,? said Paula Keener, director of education programs for National Oceanic and Atmospheric Administration?s (NOAA) Office of Ocean Exploration and Research. ?To better understand, manage and protect the ocean and its resources, NOAA believes it is critical to use the best technology to explore, discover, inform, educate and motivate? (MTS, newsletter, January 2011). In the last few decades, our understanding of the global mineral resource base has been drastically changed by some surprising new developments. The potential for commercial minerals per unit area in the oceans and seabed appears to be similar to that of the terrestrial lands. Thus, almost three-fourths of the global mineral resources are in, or under, the sea and are virtually undeveloped. The area of the Pacific seabeds alone is greater than the total area of the global lands. Half of the global seabed minerals are now controlled by nation states within their Exclusive Economic Zones (EEZ). The other half is controlled by the United Nations (UN) through the International Seabed Authority (ISA) within the ?areas beyond national jurisdiction? known as The Area. Thus, the Law of the Sea, ratified in 1994, has resulted in the largest transfer of control of natural resources in the history of mankind. This paper was prepared by the Society for Mining, Metallurgy and Exploration (SME) Committee on the Offshore Technology Conference for the SME Board of Directors and other interested parties. As the premier professional society for the mining and mineral community in the United States, with a history dating back to the 19th century, SME?s mission is to encourage and support young men and women engineers in the minerals industry, provide the services they need, improve the image of the industry, strengthen the networking among global industry professionals and engage in proactive collaboration among industry, government, academia and nongovernmental organizations (NGOs). The accomplishment of this mission can be strongly advanced by highlighting what is probably now the most significant development in the history of the modern minerals industry - the exploration of the marine environment and the understanding of the potential for the development of the minerals therein.

Jan 1, 2011

By Doug Harding

The Metropolitan St. Louis Water District’s Project Clear is a 28-year program targeting wastewater capacity throughout St. Louis, MO. The extensive program includes the Jefferson Barracks Tunnel, running parallel to the Mississippi River at 2 m ID and 5,400 m long. A rebuilt Robbins Main Beam TBM began boring but hit challenging conditions about 2,400 m in, including water inflows. A larger 4.1 m Robbins Main Beam machine will complete the remaining 3,050 m in limestone, dolomite, and shale. The TBM will utilize a high-powered, high breakout torque cutterhead along with enhanced 360-degree probing & grouting capabilities to detect any karst formations.

Dec 1, 2022

By Thomas R. Doyle

When you think of the state of Maine, you probably think of lobsters or lighthouses. The last thing you would think of is metallic mineral mining, and that is for good reason. According to the Maine Geological Survey?s website, ?no metals have been mined in Maine since 1977.? Moreover, Maine?s metallic mineral mining laws and rules, which were last rewritten in 1991, have effectively made mining in the Pine Tree State impossible. Statutory changes enacted in 2012, however, put Maine on a path to make metallic mineral mining part of the local economy in the near future. History of metallic mineral mining in Maine Currently, Maine is not a metallic mineral mining state, though that has not always been the case. The 1800s saw various mining operations in Maine, including what the Maine Geological Survey calls a ?mining boom? from 1879 to 1882, where mining of iron, silver, copper, lead and zinc expanded rapidly. Mining and mining activity in the more recent past, however, drove the debate before the state legislature when this issue was debated in 2012.

Jan 1, 2012

By Mary Ann Harrington Baker, John Trudnowski, Marietta Canty, Marek Zaluski

Three Sulfate-Reducing Bacteria (SRB) passive field-bioreactors were constructed at an abandoned mine site near Butte, Montana, to mitigate AMD emanating from a waste rock pile. Each SRB field-bioreactor contains chambers of an organic source, limestone, and cobbles. The field-bioreactors are configured differently to test the effect of different environmental conditions on the SRB. Preliminary observations indicate that, during start up and the first eight months of operation, the quantity of organic carbon supply significantly impacts the SRB activity. To date, the dissolved metals have been reduced significantly and the pH has increased.

Jan 1, 2000

By David Pentz, Paul Hodges

GENERAL INTRODUCTION The object of this paper is to discuss those aspects of open pit mine design which are affected by geotechnical factors. The temptation exists for some practitioners of geotechnical engineering to believe that this relatively new engineering discipline is the ‘be all and end all of mining.’ In the opinion of the authors, this is fallacious but, as our ability to put numbers to the behaviour of rocks and soils improves, it is clear that geotechnical engineering will become an integral and important part of designing and operationg mines success- fully. Open pit mines in the context of this paper also includes open cast mines, where the 'ore" is extracted and the waste material is immediately replaced or ' backfilled in the mined portion of the pit. Open pit mines operating today move from very small tonnages a day to in excess of 400,000 tons per day. Several mines are operating and are being designed to capital expenditure for such projects in some cases exceeds five hundred million dollars and in a few cases will exceed one billion dollars. The size of this investment means that financing will have to be provided from banks or joint partnerships. This financial environment means that planning will be carefully scrutinized by experienced representatives of financial institutions or other mining companies. All too often a project has been put in jeopardy because the personal desire of one or two men to make a project proceed has caused incomplete planning or perhaps in some instances deliberately leading observers 'down the garden path.’ In our opinion the day is rapidly arriving when the quality, logic, practicability and completeness of the planning will make the difference between securing financing or not and, in the cases of existing open pit mines, of the difference between survival and closure.

Jan 1, 1977

By Jessica M. Wempen, Dallan J. Coons, Bailey S. Simmons, Michael K. McCarter

Gate-road yield pillars are subject to increases in stress as the longwall face advances toward the pillars. Abutment loading conditions are important to gate-road layout and support design in longwall mining systems. Ground support systems are often designed based on mine experience [1,2]. Convergence monitoring is one method of ground support monitoring that can be used to infer increases in pillar stress. Convergence of a yield pillar was measured regularly over the course of six months as the longwall face approached and passed the pillar. Measurements were collected at eight locations surrounding the pillar. The convergence measurements contribute to the knowledge of when yield pillar abutment loading, caused by the encroaching longwall, is first detected. Knowing when abutment loading begins to yield the pillars can help define when standing secondary roof supports are required for head-gate entry access for specific geologic and mining conditions. 

Dunn has written an excellent paper providing a wealth of advice on what is often the most costly consumable in the mineral processing plant. As he pointed out, grinding media selection and quality control can play a major role in successful plant operation. Owing to the economic importance of this topic, there are some important factors related to media sizing that I believe merit further comment. Dunn made reference to a slightly simplified version of the Azzaroni (1981) equation and pointed out its successful use for the Henderson SAG and Climax ball mills. Although both formulas are empirically based on successful plant experience, a notable discrepancy between them is that Bond has factored the work index by the ore specific gravity. This is invariably so, as the Bond work index is derived from the mass grindability (in grams per revolution) measured in a test mill with a fixed volume of solids load (Bond, 1961). A material having the same structural integrity but double the density of another will have double the grindability and just over half the work index. Thus, for the general case, specific gravity should be incorporated into any media sizing formulation that uses work index as the criterion for resistance to breakage.

Jan 1, 1990

By Robert O. Vernon

Urban sprawl, and all its attendant problems, is upon us. In Florida, and much of the rest of the world, this has been intensified by a special problem - the coastal zone - a land of high-intensity urbanization localized where the sea and our citizens interact. Florida is blessed by a long coastline of beautiful beaches, indented by estuaries, lagoons and spring fed rivers. Rocky and sand covered islands invite habitation. A large and varied fauna and flora make recreation an avocation and work a pleasure. Accompanying these people are all the sustaining, and satellite industries that find the climate, labor, and commodity markets, cheap water transportation, and natural resources to be attractive. It is estimated that by the year 2008 a megalopolis will stretch down the Atlantic Seaboard from Georgia to encompass the Keys and extend along the Gulf to Alabama. This city will be fenced by the sea on one side and by the water management works, necessary to provide the water supply for this complex, on the other. What can we do about increasing the amount of water available for this population and decreasing the resultant wastes??? Rarely has there been tendered a more favorable opportunity for a coordinated planning and development project that will provide public access to beaches and multiple use of the coastal lands. Florida, as a peninsula swept by ocean breezes, having a largely indigenous water supply and only the beginning of the pollution of estuarine and coastal waters can cope with air, water and coastal dissipation and pollution, if we have a beginning at providing a constant water supply and at limiting pollution. This answer would appear to lie underground, where the porous limestones are interbedded with impervious fine-grained sediments and ground-water that circulates through these aquifers empty to the ocean and Gulf along the continental slopes.

Jan 1, 1969

By T. J. Fenner

Research conducted in South African mines has demonstrated the benefit of ground penetrating radar for the detection of geologic features and hazards. This is crucial for safety and production considerations in underground mines that are as much as 4 kilometers deep. This paper describes a new ground penetrating radar system designed specifically for high quality data acquisition, in the harsh conditions of deep underground environments, for use by operators with minimal geophysical experience. Design criteria included automated functions, intrinsic safety, light weight and minimal power requirements. Data is processed on the ground surface by geoscientists using a PC.

Jan 1, 1994

By J. M. Wempen, R. D. WEYHER, M. K. McCarter

Beam theory is a proxy for the behavior of intact, deforming roof strata above underground openings. Strong, stiff, intact strata have the ability to store significant strain energy when underground openings have large spans, as is typical of longwall operations. When strata fail, they may release some or all of this strain energy. Released energy is partitioned between fracture, thermal and seismic energy. The tensile failure surface in simply supported beams is predicted to be free of shear stress. This prediction and the kinematic inability of crack slip during fracture make significant dissipation of energy by friction unlikely.  In this study, the failure energy partitioning of specimens from the Nugget Sandstone formation is examined. Tensile fractures in specimens were induced using three-point loading tests. Elastic waves emanating from fracture events were recorded using an array of accelerometers. Accelerometers were placed within two crack lengths of the fracture surface, and the acceleration records are similar to strong motion seismic records. Spectral analysis was performed and used to develop synthetic, well-behaved, acceleration signals. Synthetic velocity signals were used to estimate radiated seismic energy generated by fracture. These estimates of radiated seismic energy demonstrate a potential means to constrain the minimum seismic partition. Fracture testing was performed on additional samples to estimate the fracture toughness of the sandstone. Synthesis of this data demonstrates a potential means to constrain a maximum seismic partition. Bounding the seismic partition for this type of fracture event could aid the detection and evaluation of seismicity emanating from longwall operations. Having better information about the location and magnitude of mining induced seismicity within longwall overburdens could lead to better understanding of extraction sequencing and rock behavior in general. These energy estimates also support the hypothesis that dissipation of thermal energy by friction is small in bending tensile failure.

By M. G. Premo

The McKinley Mine is located in the northwest New Mexico, in McKinley County, approximately 25 miles from Gallup. The mine is operated by The Pittsburg & Midway Coal Mining Co. (P&M), a wholly owned subsidiary of the Chevron Corporation. P&M is headquartered in Englewood, Colorado. Since the McKinley Mine began operations in 1962 a total of 83,391,000 metric tons of coal have been sold through 1990. The 1991 production was approximately 5.000.000 metric tons. The mine operations are contained on a 109.000 square kilometers lease area of which 44.000 square kilometers are on the Navajo Nation. The present customer base consists of four utilities and one industrial account, all of which are located in Arizona. The utility customers are the Arizona Public Service Co. Cholla Station at Joseph City, The Salt River Project. Coronado Generating Station near Joseph City, and The Tucson Electric Company, Irvington Generating Station in Tucson. The industrial customer is the Stone Container Corporation, Snowflake Paper Mill.

Jan 1, 1992

By J. R. Caylor

The Mine Safety and Health Administration (MSHA) advanced several initiatives last year to further protect miners' health. Regulatory efforts included the implementation of a Hazard Communication rule for all mines, work on the Single Sample rule for all coal mines, and the Plan Verification rule for underground coalmines. Development and application of new technologies are actively encouraged in preventing miners' hearing loss and respirable dust overexposures. MSHA's successful x-ray program for screening of black lung among coal miners completed its third year. Compliance Assistance efforts are focused on Best Practices, outreach, and technical support for operators' specific challenges.

Jan 1, 2003