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By Bruce W. Woolpert

During the SME Board of Directors’ midyear meeting in Monterey, CA Aug. 25, I discussed trends in the construction aggregates industry. Many construction-material suppliers may not have yet fully internalized the changes that are taking place. But the changes are significant. And they have shifted the focus in the aggregates industry from “assets” to “people and innovation.” Construction-material suppliers serve many customers. A typical quarrying operation at Graniterock would have more than 1,000 customers, mostly civil engineering contractors. Along with the push toward people and innovation, there is increased emphasis on vertical integration from aggregates to ready-mix concrete and hot mix asphalt, to final construction. If a company is not vertically integrated, it will at least have strong partnerships with other firms, to deliver a high-quality finished project on time.

Jan 1, 2002

By Jr. Gambrell

Support characteristics of in-cycle trusses are analyzed using a photo-elastic model loaded by tightening a truss in the sequence normally used in an underground mine. Stresses in the roof at its center point and at the junction of the roof and rib are examined. Effects of zero tension and unequal tension in the inclined anchor rods are presented. Effects of simulated subsidence on stress in the roof surface and on tension in the separate truss members are examined. Conclusions are drawn relating to (1) the effects of tension in the inclined anchor rods on uplift and compressive stress parallel to the roof surface, (2) the effects of subsidence on stress in the roof surface and, (3) the effects of subsidence on tension in the truss members.

Jan 1, 1989

By Yuting Xue, Todd Minoski, Daniel Su, Mark Van Dyke, Mark Mazzella, Steve Hicks, Zoheir Khademian, Nicole Evanek

Design of chain pillars in a longwall mine setting is one of the main engineering controls on the global and local stability of the mine. Challenges with roof instabilities, floor heaves, and pillar failures can be alleviated, to some extent, by careful design of gateroad configurations and chain pillars. This work investigates three different alternative designs in a three-entry-system gateroad configuration with an inter-panel barrier in a longwall mine in Virginia. Starting with the current design, which has faced challenges such as excessive floor heave, a geomechanical model developed in 3DEC software is validated by monitoring in-situ pillar stress in the yield, abutment, and barrier pillars in the mine. Next, three different chain pillar designs are evaluated in the model with a focus on roof sagging, floor heave, and pillar average stress. Results show the relationships among the alternative designs and instabilities associated with roof, pillar, and floor in the study mine, providing insights for optimizing longwall mining designs in deep-cover settings.

Feb 1, 2025

By TOMI GIORGIO DE, Ricardo Tichauer

Mineral exploration is a key factor for success in the mining industry. However, exploration best practices are often ignored in small-scale mining. This works presents the Tichauer-DeTomi Matrix, a methodology that measures the level of compliance of exploration programs in small-scale mining with the industry best practices. The matrix has been applied to three projects in Brazil: an artisanal gold mine in the state of Pará, a small-scale manganese project in the state of Bahia, and a small-scale manganese project in the state of São Paulo. The application of the matrix resulted in indexes that represent the level of maturity of the exploration program in each project and indicate priority actions for reduction of the geological uncertainty. Therefore, the Tichauer-DeTomi Matrix has shown potential to be a useful tool for assessment of geological uncertainty in small-scale mining. As a risk indicator, it may contribute to promoting investment in small-scale mining and development for communities that depend on this activity around the world.

By William F. Stowasser

The United States has traditionally been the world's largest producer and net exporter of phosphate rock and related fertilizer products with the exception of rock exports from Morocco. In recent years, however, U.S. producers have faced increasing competition from operations in foreign countries, leaving the future position of the U.S. phosphate .industry as a leader in the world markets somewhat less certain. This paper will review the U.S. phosphate rock industry in relation to its known demonstrated reserves, its historical and present production and export levels, and its future mining potential. The paper will include an analysis of the availability of phosphate rock in the United States represented by cost-tonnage relationships. The U.S. phosphate rock industry has for decades provided raw materials at reasonable costs to the phosphate fertilizer industry, and the fertilizer products have been made available to both domestic and international markets. Natural soils normally contain low quantities of phosphorus, and cultivation exhausts the available phosphorus through the removal of harvested products. Yields diminish, and it becomes necessary to apply phosphorus to the soil in an amount at least sufficient to compensate for removal. Raising the level of phosphorus also permits nitrogen and potash fertilizer nutrients to be effective and sustain the high crop yields necessary to support increasing food demands. In only a few areas of the world are soils, climate, rainfall, and low-cost phosphate fertilizer available to assure high agricultural yields in successive years. One of these areas is the central United States and south central Canada. By contrast, in the Soviet Union, the weather conditions in farming areas frequently cause crops to either bake or drown in the field. To attempt to counter the effect of weather on production, the U.S.S.R. has increased use of fertilizer and equipment in recent years. The effect of fertilizer on various crops has been documented, and in all cases, improvements in yield and plant development were noted, as was the ability of fertilizer to mitigate the effects of unfavorable climatic conditions. Phosphate resources can be classified as either identified or undiscovered. In the identified classification, we are principally concerned with demonstrated phosphate resources, or those that have been measured or indicated. In the southeastern United States, the phosphate mining areas of Florida and the Carolinas have been explored and drilled extensively in attempts to locate new deposits. The exploration programs indicate that another Florida Bone Valley Formation or North Carolina Pamlico River Deposit is unlikely to be discovered in the southeastern U.S. coastal plain. Phosphate rock deposits of commercial interest in the western United States are located in Montana, western Wyoming, northern Utah, and southeastern Idaho. The deposits are in the Permian Phosphoria Formation with most of the mining activity occurring in Idaho. Although substantial demonstrated resources have been identified, recovery costs and the field's isolation from markets have restricted growth of the industry in the west. The phosphate rock deposits in Tennessee are well known, and it is estimated that about 29 million metric tons1 are potentially recoverable. Undiscovered deposits of brown rock in Tennessee would likely be quite small.

Jan 1, 1985

By Hamid Maleki

Mine seismicity is influenced by the mechanical properties of both near-seam strata and overburden/underburden and the prudent selection of mining methods and mine layout designs, utilizing sitespecific structural setting of the mines. The importance of adequate data collection, monitoring, and prudent structural designs has long been recognized and utilized in many U.S. operations with adequate engineering resources. In this paper, two case studies of historic seismic events and contributing factors, in deep coal and trona mines with overburden thickness exceeding 1,500 ft, are reviewed using observations and analysis. By back analyzing the overburden response in a historic room-and-pillar coal mine, the overburden collapse mechanism associated with a 3.3 magnitude seismic event is reviewed as well as the need for improvements in designs including panel and barrier pillar widths. Similar high-order seismic events were also experienced in trona mines of the Green River Basin during 1990s, interrupting room-and-pillar mining and creating ground control concerns. Efforts to improve structural mine designs are described in this paper leading to stable and productive operations for decades following the high-order seismic events in both coal and trona case studies. These efforts included improving room-and-pillar extraction layouts and utilizing properly designed longwall mining techniques that were verified using long-term geotechnical instrumentation. The study mines are located on the Wasatch Plateau (WP), Utah and in the Green River Basin (GRB), Wyoming. More recently, in Utah’s East Mountain alone, Energy West Mining Company (EWMC) has extracted some 165 million tons of coal without any significant incidents. Overall, favorable geologic conditions and prudent mine layout designs are key elements to this successful experience in both single- and two-seam layouts. Utilization of conservatively designed longwall mining technique in the GRB has been geotechnically stable, using reported experience in 15 panels and monitoring results in the Northwest (NW) District with measurable longwallinduced seismicity being rare. These studies demonstrate a considerable amount of progress that has been made within the last four decades in the application of longwall mining technique, integrated monitoring, and analyses for the verification of structural designs in mines in the United States.

Jul 1, 2023

By Ron Robinson

Booster fans have been in regular use in British coal mines since the first half of this century, but a large increase in their use did not take place until after the Nationalization of coal mines in 1947. From that time the need was identified to improve standards of ventilation in general and mining engineers specializing in ventilation were appointed at all levels in the mining industry. A comprehensive approach to ventilation surveys and planning, together with the realisation of the benefits of booster fans, led to their more rapid introduction. Many coal mines in the U.K. are at moderate depth and have virgin strata temperatures of 30°C or less. The ability to control climatic conditions by increased ventilation rather than resort to cooling systems has led to the introduction of booster fans and recirculation systems in these mines. Large makes of methane and high levels of coal dust production due to increased mechanization have also required enhanced ventilation standards. This paper deals with the reasons for selecting booster fans and the specific safety considerations involved in their use. Numbers, types and sizes of booster fans in the U.K. are outlined, together with notes on installation and performance. Remote monitoring and control from the surface is dealt with, and current legislation. The evolution of controlled recirculation is also covered starting with auxiliary fan systems in 1970 and leading to very large district schemes in the late 1980s. The research at Newcastle upon Tyne University and other establishments in the climatic conditions associated with recirculation is summarised and its use in assisting existing and proposed conventional and recirculation systems is indicated.

Jan 1, 1989

By J. Gustavson, E. Mallard, F. Pirkle

The Sales Comparison Approach to estimating the value of a mineral property must always be attempted1 . In addition to other parameters, the approach depends heavily on the availability of transaction data. The consideration for the mineral property must be in form of cash, cash equivalent or other consideration. In other words, “What dollar amount did the property sell for?” Mineral properties are generally real estate, albeit frequently buried deeply under the overlying surface real estate, unless the property may be a quarry. In some states, transactions must be recorded in county courthouses, and the sale consideration must be included. In such cases, the appraiser’s job is made easy. In other locations, the sale considerations are withheld in the courthouse data; but occasionally a local transfer tax is collected and recorded. Again, the appraiser’s job is made easy by back calculation with knowledge of the legislated transfer tax percentage. The worst problem occurs when the consideration for a mineral real estate sale is totally withheld. That may occur in so-called nondisclosure states. A recent map2 of ten non-disclosure states in red is shown below. For the full color code, please refer to the footnote

Mar 2, 2022

By H. M. Giegerich

About Cominco Only the original Broken Hill zinc deposit in Australia is larger than Cominco's Red Dog deposit. Indeed, the third largest zinc deposit in the world is Cominco's own Sullivan mine in British Columbia. The production plan at Red Dog is based on mining 1.9 Mt/a (2.1 million stpy) or ore, to produce 635 kt (700,000 st) of zinc and lead concentrates. At full production, Red Dog will be the largest zinc mine in the Western world. It will also be one of the lowest cost producers in the Western world. And Red Dog will be one of the first major hardrock mines to operate in Alaska in modern times. The Red Dog project will be the third and largest of Cominco's Arctic mining developments in the past 13 years. The company's Black Angel mine in Greenland started up in 1973. And the Polaris mine, high in the Canadian Arctic, began production in 1982. Red Dog is one of the world's great mineral deposits. It is a unique combination of large size, high grade, and a waste-to-ore ratio less than 1:1. The present mineral reserve (Table 1) is estimated to be 77 Mt (85 million st), at a grade of 17.1% zinc, 5% lead, and 82 g/t (2.4 oz per st) of silver. Mine life is estimated at nearly 50 years. Cominco is the largest producer of lead and zinc in the Western world. Cominco's smelter in southern British Columbia is the largest lead and zinc plant in the west. Cominco also produces copper, steel, tin, gold and silver, along with potash, ammonia, urea, and phosphate fertilizers. But Cominco's major products are lead and zinc. At present, Cominco produces more than 10% of the Western world's needs for these metals. Background-Red Dog The Red Dog mineral deposit is located in northwestern Alaska, about 960 km (600 miles) by air from Anchorage, Alaska's largest city. The Red Dog region is home to more than 5000 people living in 11 villages. The largest village is Kotzebue, with a population of about 2500. The village is located about 144 km (90 miles) southwest of the mine. The country around Red Dog features rolling hills, leading into mountains to the north and east. The deposit, at an elevation of 305 m (1000 ft), is in permafrost. But the area is not nearly as cold as that encountered in the Canadian Arctic, or on Alaska's North Slope. At Red Dog, the permafrost is relatively fragile. It can be thawed fairly easily, a factor in engineering designs. Red Dog Creek flows through the mineral deposit. One of the natural phenomena at Red Dog is the presence of significant heavy metal contamination in the creek. This has eliminated all fish in the vicinity of the deposit. The contamination, and resulting mineral stain, led to the discovery of Red Dog. The staining is caused by rain and snowmelt. This leaches the heavy metals from the mineral zone, which comes right to the surface in many places. As mining progresses, this surface mantle will be removed. This will

Jan 12, 1986

By CAIJUN CHEN, MING ZHANG, ZHENWEI WU, FENG ZHOU, BOQUAN LI, XILIANG ZHANG, ZHOU PU

Traveling grate is a widely used process for iron ore pellet production, but the thermal state of pellets in the drying section is still unclear. In this study, the temperature distribution of the drying section was investigated using computational fluid dynamics (CFD). The results indicate there is a coupling effect in the drying section of a traveling grate. Gas with higher temperature in down-draught drying (DDD) transfers heat to the up-draught drying (UDD) through the gap of the insulation board, and the temperature gradient of the pellet bed changes before reaching the insulation board. The characteristics of pellet bed expected to appear in DDD are displayed in UDD in advance. To verify the model, a contrast experiment was conducted.

By Stephen G. Whittaker, Rosalind A. Schoof, Martha J. Steele

In determining remedial action objectives for metals in soils, the U.S. Environmental Protection Agency typically assumes that the metal concentrations in house dust are the same as the metal concentrations in soil. Data now available from several studies that were conducted in mining communities suggest that for some metals, concentrations in house dust may be lower than those in soil. This paper reviews available data on the relative soil and indoor dust concentrations of arsenic and cadmium and examines how changing assumptions regarding indoor dust concentrations of arsenic affects risk assessments and determination of cleanup levels.

Jan 1, 1992

By Peter Zhang, Mark Van Dyke, Ted Klemetti, Morgan Sears

Room-and-pillar mining is a mining method used in the United States to extract coal from underground, and pillar recovery is widely practiced for maximizing coal recovery and mining economics. Under certain conditions, room-and-pillar mining can create high stresses in coal pillars resulting in a coal outburst. These outbursts represent one of the more severe safety hazards in underground coal mines, potentially causing injuries and fatalities. Over the past ten years, coal outbursts have resulted in three fatalities in U.S. room-and-pillar mines. Though coal outbursts generally occur under deep cover, they are more likely to occur during pillar recovery and under multiple-seam mining conditions. Coal outbursts are generally associated with strong roof and floor and heavy loading of coal pillars, but it is difficult to predict whether, where, and when they will occur. In this respect, risk management provides a proactive tool to prevent coal outbursts in room-and-pillar mining by identifying mining areas with high risk of outburst and mitigating the risk accordingly.

Apr 26, 2022

By J. W. Wilson, S. Nakajima, B. D. Singh

According to the Project Independence blueprint, a 270 percent increase in coal production is expected from western coal fields compared to an increase of 100 percent for the nation as a whole. Furthermore, 30 percent of the total United States coal reserves lie in the western states, which are classified as beyond the strippable limits and can be recovered only by underground methods. In view of the fact that the majority of the seams in the West are thicker than those presently mined in other parts of the country, it is important to consider the parameters that relate to mining thick seams and the factors that affect such mining systems. Apart from thick seams, a common feature of many western coal fields is the occurrence of multiple seams that lie in close proximity to one another. These multiple seam deposits present difficult mining problems that have not been encountered to any degree in other U.S. coal fields; for example, ground pressure changes in one mine level caused by mining in the other, sudden water or gas influx from the adjacent levels, the danger of spontaneous combustion in gobs and large and complex subsidence displacements on the surface. Perhaps equally important is the fact that the country can ill afford the present systems of underground mining that attain only 50 to 60 percent coal recovery. With the probability of increased thick seam mining, conservation shall be a focal point in future mine design systems. It is possible that in the future it will be forbidden to adopt the present day wasteful mining methods to ensure that coal can be conserved for future generations.

Jan 1, 1977

By A. W. Laughlin

Laser-Induced Breakdown Spectroscopy or LIBS can be used to provide exploration companies with precise and accurate chemical analyses in the field, in real-time, resulting in major time and cost savings. Using a Field-Portable Analyzer (FPA), anomalies can be followed up immediately while crews are still in the field. Lower limits of detection (LLDs) are element dependent, but many are sufficiently low to be useful in exploration. LLDs in ppm for selected elements of interest are: Be-2, Cu-3, Zn-20, As-200, Sb-500, Pb-30, Ag4, Mo-100, B-33, Ti-500, V-350, and Cr-1. LIBS analyses require little or no sample preparation.

Jan 1, 1999

By F. K. Spragins

The growing demand and a diminishing supply of conventional crude oil in North America are bringing about an ever increasing interest in the so-called "synthetic fuels". With one commercial plant already in full production, another in the planning and engineering stage, and still others being seriously considered, the Athabasca tar sands is proving to be a leading center of interest. Here, and in the closely related deposits, reserves in place total over 700 billion barrels.1 This major source of new oil is about ready to play a significant role in the filling of ever increasing market demand. When and if fully developed, the Athabasca tat sands could make both Canada and the United States substantially independent of all off-shore supplies of crude for many years to come. Its product, a high-quality, low-sulphur synthetic crude, is beginning to enter the market place at a most favourable time.

Jan 1, 1972

By Larry Lynott

This paper summarizes the benefits ofusing an in-situ analyzer in a sampling and valuation program. The tests and studies cited quantify the problems associated with current conventional sampling techniques and contrast conventionally-obtained results with those obtained through in-situ analysis. Data are presented to show the improved precision in valuation resulting from the in-situ method. Greater precision in estimating the mineral content of unmined ground becomes increasingly important as mines strive for optimum exploitation of their deposits. As the following analysis shows, the variable distribution of minerals within a deposit, along with the difficulty and the cost of high density sampling limits the precision which is currently possible in practice. An inherent problem exists in the conventional method of sampling. The erratic values of ore grade necessitate the collection oflarge numbers of samples for statistically accurate valuation and ore reserve estimation. Owing to the cost of manpower, current sampling techniques do not allow for the collection of sufficiently large numbers of samples. The most common method of sampFng in current practice is chip sampling, although bulk sampling is sometimes used. The intent of sampling is to obtain an estimate of the value of blocks of ground prior to mining. This information is used to plan the rate and sequence of mining, yet the sampling intervals which are possible in practice cause these block estimations to be ubject to considerable uncertainty. This inevitably leads to mcorrect mining decisions which may be vy costly.

Jan 1, 1998

By Thomas F. Pedersen, J. Jay McNee, Alan J. Martin

Field sampling was conducted in Lake Junin, Peru in order to assess the post-depositional reactivity of the highly contaminated lake sediments. High resolution profiles of dissolved Fe, Mn, SO42- and H2S across the sediment-water interface illustrate that the organic-rich sediments in the main basin become anoxic within several millimetres of the sediment-water interface. These permanently submerged deposits in the main basin serve as a diffusive sink for dissolved Zn and Cu. Conversely, the periodically unsaturated deposits in shallow areas are characterized by the remobilization of Zn and Cu in the deep acidic (pH < 4) pore waters, resulting in the release of these metals to the overlying water column.

Jan 1, 2000

By W. M. Kidd, P. J. Duport

INTRODUCTION The enquiry of the Royal Commission on Health and Safety of Workers in Mines of 1976, known as the Ham Commission after its chairman, Dr. J. Ham , now president of the University of Toronto, was one of the activities surrounding the upturn in the fortunes of the Canadian uranium industry and its markets in the mid-seventies. Although the regulation and licensing of Canada&apos;s ten major mine/mill facilities employing six thousand or more uranium mines is a federal concern under the Atomic Energy Control Act, this Commission, which paid particular attention to health and safety in uranium mines, was appointed by the Province of Ontario. Further provincial enquiries in British Columbia, Saskatchewan and Newfoundland have been aimed at quantifying, reducing or eliminating the environmental and health impact of uranium production. This work has created a mosaic of provincial regulation in what is essentially a field of federal jurisdiction. Various organizations of the federal government related to its regulatory function in the uranium industry are outlined in Figure 1 showing the matrices of regulatory, advisory and research activities associated with the exploitation of Canadian uranium resources. A more detailed examination [ ] of the governmental (federal and provincial) activities, commissions, etc., in the Canadian uranium industry indicates a definite parallelism of effort, if not of scale between the two levels of government in the execution of their roles in occupational and environmental health and safety and is presented here to explain the complex stage onto which the Canadian Institute for Radiation Safety has just entered. The development of the Institute and its precursors together with current and planned research activities are described. BACKGROUND Traditionally and constitutionally, natural resource exploitation and its regulation is under provincial jurisdiction; however, the uranium industry has been under federal control since the Second World War when security measures necessitated the creation of the Atomic Energy Control Board (AECB). Health and safety aspects, in terms of inspection, compliance and environmental monitoring are performed on behalf of the AECB by provincial labour inspectors (Saskatchewan and Ontario) and Ministries of Environment. Non-radiation health and safety matters are also enforced under the federal Canada Labour Code by provincial inspectors. In support of licensing and standard-setting functions, major research programs have been initiated and expanded at both the AECB and the Canada Centre for Mineral and Energy Technology (CANMET), formerly the Mines Branch of the Federal Department of Energy, Mines and Resources). CANMET established a Mining Research Laboratory at Elliot Lake, Ontario in 1965 to conduct research and development aimed at improving production capability, providing information on the security of uranium supply and investigating the hazards of mining and their implications for the health and safety of the miners. The provincial route in assessing the costs and benefits of uranium production has attempted to be far more conclusive in nature. While some on-going studies are funded, periodic inquiries by Royal Commission have become the accepted practice. Six such inquiries have been conducted in four provinces and widely differing policies have resulted from their findings and recommendations. For example, while the government of British Columbia in the Fall of 1980 declared a seven-year moratorium on(2) uranium mining and exploration in the province, the province of Ontario&apos;s crown utility "Ontario Hydro" financed the rehabilitation of a mine/mill complex at Elliot Lake. The latter instance is not surprising considering that the final report of Ontario&apos;s "Royal Commission on Electric Power Planning",(3) concluded that nuclear energy has a continuing role to play in the expansion of Ontario Hydro.

Jan 1, 1981

By Peter Zhang, Todd Minoski, Gabriel Esterhuizen, Jack Trackemas, Berk Tulu, Morgan Sears

Roof stability in the belt entry is critical for safe and continuous production of coal during longwall mining. Previous studies of roof falls that occurred in belt entries have shown that the roof falls were largely associated with high in situ and longwall-induced horizontal stresses [1,2,3,4]. To properly support the roof in a belt entry, it is important to understand how longwall-induced horizontal stress changes can affect roof stability in the belt entry. Monitoring of horizontal stress changes was conducted in the belt entries of two Pittsburgh seam longwall panels oriented unfavorably to the major horizontal stress. Numerical models were also set up to investigate how horizontal stress concentrates and relieves in the belt-entry roof near the face as panel orientation changes. Both measurements and modeling results show that high horizontal stress concentrates in the belt entry roof within about 15 m outby the face. The study demonstrates that longwall-induced differential horizontal stress can be used to evaluate the horizontal stress concentration factors. The horizontal stress concentration factors change with panel orientation, resulting in high stress concentrations at orientations between 20 and 110° and low stress concentrations between 130 and 180°. Roof support strategies are given for the belt entries under the influence of high horizontal stress. For unfavorably oriented panels in weak roof conditions, supplementary support should be installed during development, and cable bolts should be anchored into a stable roof horizon. The bolting pattern should be designed to cover both entry corners and the entry center to prevent potential roof cutters and sagging.

Jan 1, 2023

By N. L. Parduhn

Populations of Bacillus cereus spores are elevated in soils over four subsurface gold deposits in the western United States. Large deposit-to-background ratios of B. cereus populations were obtained in soil traverses over the Minnesota vein deposit, Empire District, Colorado (maximum 50:1); the Shasta (maximum 3,500:1), and Evening Star maximum 18,000:1) vein deposits, Shasta County, California; and the Hog Ranch disseminated gold deposit (maximum 40,000:1) in Washoe County, Nevada. Small increases in the concentration of toxic metals in the soil may be responsible for the elevated spore populations. The observed elevation of B. cereus spore populations near these gold deposits indicates that the method should be further investigated as a potential exploration tool.

Jan 1, 2013