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By J. H. Kempton, D. Atkins

Predictions of delayed environmental impacts from mining—degradation that won’t begin for hundreds of years, but will then continue for thousands—present new permitting challenges. Examples include evaporative concentration in pit lakes, which can eventually cause metals concentrations to exceed human and wildlife toxicity standards, and delayed degradation of groundwater by slow moisture percolation through acid-generating tailings and waste rock. Given the time-value of money, the present worth of such delayed impacts is insignificant, yet they are unacceptable undercurrent laws and cultural values. Long-term financial set-asides offer a possible solution, first funding infrequent, long-term monitoring, followed by more expensive mitigation when the set-aside has matured.

Jan 1, 2000

By D. J. Pandelis, W. J. Schlittler

Auxiliary Equipment pumping systems to support primary, secondary and regrind grinding circuits will be the primary focus of this paper. Every grinding system is unique and requires special design considerations for proper application of pumps to transport mill discharge. To satisfy the majority of applications, a new series of pumps has been developed by Svedala, known as World Class Pumps. Selection of these newly developed pumps for each type of grinding circuit will be presented. Specific components of selection are materials of construction, piping system, classification method, material characteristics and slurry characteristics. Both horizontal and vertical pump applications will be reviewed with emphasis on rules of pump piping and sump design.

Jan 1, 1999

By U. K. Custred

Who We Are Farmland Hydro (FHLP) is a Limited Partnership formed by Farmland Industries, the largest U.S. farmers’ cooperative, located in Kansas City, MO, and Norsk Hydro, a large Norwegian company engaged in fertilizer, petroleum and the specialty metals industry. Both of our parent companies have a long history of commitment to the fertilizer industry. This year, Farmland Industry celebrates its 71st year in the business, and Norsk Hydro celebrates its 100th operating year! We employ approximately 300 associates in Central Florida. What We Do Farmland has been active in Hardee County, FL since the 1970’s as a large landowner and citrus grower. We plan to expand this activity into phosphate rock mining. The phosphate rock produced here will be shipped to our nearby chemical fertilizer complex in Polk County, where we produce quality phosphate products - liquid and granular fertilizers. Of the phosphate rock mined, 90% is used to make fertilizer. Other uses include animal feed, vitamins, medicine, light bulbs, soft drinks, film, flame resistant fabric, optical glass, toothpaste, bone china and other consumer products.

Jan 1, 2000

By C. L. Van Dover

Organisms living at hydrothermal vents are adapted to catastrophic disturbances in their environment caused by processes such as tectonic activity and mineralization that shift the locus of fluid flux and volcanic eruptions that pave over active systems and reset the hydrothermal cycle. The scientific community appreciates this risk of natural, local loss of species, genetic, and habitat diversity. The risks of more profound loss of diversity and ecosystem function and health as a consequence of additive commercial activities in hydrothermal systems are unknown, and are not the same across all deep-sea hydrothermal systems. Vent communities differ from one ocean basin to another, as do the geological settings and geochemical dynamics of vent systems. Communities on the East Pacific Rise represent one end-member in the catalog of hydrothermal vent communities. In these systems, the life cycle of a hydrothermal field is on approximately the same time scale as the lifespan of the species that live there. From studies of the 1991 and subsequent eruptions at 9N on the East Pacific Rise, we understand the rapidity with which new vents are colonized when nearby brood stocks are available to repopulate the system. Almost instantaneously, microbial biofilms and mats form, followed quickly by invasion of mobile opportunistic organisms (especially crabs, copepods). In a matter of a few months, a predictable succession of sessile organisms recruits, grows, and reproduces. Within two to three years, the system returns to levels of species diversity that begin to match those of the pre-eruption condition. Vents on the Mid-Atlantic Ridge (MAR) represent a different end-member, with catastrophic disturbance rare relative to the life span of the organisms that make up the bulk of the biomass. We have no experience with an eruptive event or other major transformation of venting activity on the MAR and thus have no knowledge or insight regarding the time it would take for the biological diversity to return to pre-cataclysmic levels.

Jan 1, 2008

By C. A. Pryor

The aggregates industry is the largest minerals industry in the United States producing over 2.6 billion metric tons of crushed stone, sand and gravel annually. Approximately 5% of that production is fine material, passing a 75-micron mesh sieve. Of that amount, about 77% is not sold and represents one of the major industry issues. The material accumulates in stockpiles and settling ponds having an operational and economic impact on the site’s bottom line. Many factors cause this material to be produced: from blasting and processing techniques all the way to end use specifications.

Jan 1, 2002

By Y. Wang

China is a big mining country with a long mining tradition and history. At present, there are nearly 200,000 different mines and 21 million workers. The total production value of mining makes up 6% of GNP. With the development of economy, the mining industry has played a more important role in our economic market, supplying more than 95% non-reusable energy, 85% of industrial and agricultural raw materials, over 75% of fertilizers and 30% industrial and agricultural water.

Jan 1, 2001

By Bart Bartholomew, Randall J. Essex

INTRODUCTION In June of 2004, at the North American Tunneling Conference in Atlanta, an all-day workshop was conducted to review the application of Geotechnical Baseline Reports (GBRs) for underground construction. The moderator for the program was Bart Bartholomew, former President of Fruin Colnon Construction Company. The program involved commentary by a panel of engineers, owners, contractors, and legal representatives within the North American tunneling industry, as well as an extended audience discussion. The panelists were: Peter Douglass, President, Peter Douglass, Inc. Randall Essex, Executive Vice President, Hatch Mott MacDonald Joseph Gildner, Deputy Director for Technical Services, Sound Transit Randall Hafer, Esq., Kilpatrick Stockton Robert Fitzgerald Esq., Watt, Tieder, Hoffer, & Fitzgerald Kirk Samuelson, Senior Vice President, Kiewit Construction Group DEVELOPMENT OF PROGRAM FORMAT The focus of the program was to assess the state of the practice in the preparation of GBRs, and to discuss improvements that could and should be made with regard to their preparation, interpretation, and application. The approach used to achieve this focus in the broadest possible way was unique, in that it involved the panelists’ preparation of the workshop format and materials months before the presentation of the workshop. First, each of the six panelists was selected by the moderator based on their reputation and involvement in their respective fields of expertise, taking care to maintain balance and contrast within the collective pool of talent assembled. Following selection and agreement to serve on the panel, each panelist was asked to independently submit to the moderator a list of the six most pressing issues involving GBRs that they each frequently encountered in their individual professional experience. Each was asked to rank their issues in descending order of perceived importance. This process resulting in a pool of thirty-six potential or “candidate” issues for use in the workshop program. Contrary to the moderator’s expectations, there was surprisingly little duplication among the thirty-six issues submitted.

Jan 1, 2005

By M. A. Stoakes, H. D. S. Miller

Surface subsidence is becoming an increasingly important factor in the economics of mining Louisiana salt domes due to, amongst others, excessive shaft deformations and land loss to encroaching sea water. The vast majority of subsidence studies have been undertaken on bedded, tabular deposits. It is important to understand the causes of subsidence due to mining domal salt and how it can be minimized. The paper will review the major differences between subsidence caused by domal and tabular evaporite mines, the problems encountered in predicting subsidence, the factors that influence subsidence and, finally, possible alternative mining methods.

Jan 1, 1986

By Bruce A. Kuyper

Routine core drilling at the Cove deposit failed to confirm gold-silver grades and length of intercepts observed in reverse circulation drilling. A drilling program was designed to ascertain whether the disparity was due to problems with reverse circulation drilling techniques, core drilling techniques, or the erratic nature of the gold-silver mineralization. Special sampling devices and core drilling methods were employed. Data obtained from core-reverse circulation twins showed that down-hole contamination during reverse circulation drilling accounted for much of the variation between reverse circulation and core drill results. Down-hole contamination occurred as a result of high ground-water inflows eroding friable vein material from hole walls.

Jan 1, 1991

By J. B. Hedrick

Rare earths were not mined in the United States in 2008. However, processing of intermediate rare-earth concentrates continued throughout the year at the Mountain Pass Mine in California. Consumption of refined rare-earth products increased. U.S. rare earth imports were primarily from China, with lesser amounts, in decreasing order, from France, Hong Kong, Japan, Austria and Russia. The United States imported 100 percent of its supply of yttrium metal and compounds primarily from China. United States In 2008, lanthanide concentrates were processed by Chevron Mining Inc. (previously Molycorp Inc.) at its mine site at Mountain Pass, CA. Chevron Mining sold its entire holdings in the rare earths mine to Molycorp Minerals LLC in September and operations continued at the site through-out 2008. Major uses for these mineral commodities were in automotive catalytic converters, petroleum fl uid-cracking catalysts, permanent magnets, glass-polishing compounds, ceramics, metal-alloying additives, phosphors and recharge-able batteries. Three domestic companies produced and sold lanthanide intermediate concentrates and refined products. Chevron Mining sold its interests in the Mountain Pass Mine to Molycorp Minerals LLC on Sept. 30, 2008. Molycorp Minerals LLC is an investment company owned by Resource Capital Fund IV L.P., Pegasus Partners IV, LP, The Goldman Sachs Group Inc., Traxys North America LLC, Carint Group LLC and Mark Smith. The Molycorp operation previously mined the rare earth fluocarbonate mineral bastnäsite by hard-rock surface methods, and the mine remained on care and maintenance in 2008. Molycorp maintained significant stocks of bastnäsite concentrates, intermediate concentrates and high-purity rare earth compounds at its operations at Mountain Pass. In October 2007, Chevron Minerals completed phase one of its three-stage plan and restarted the rare earth separation plant at Mountain Pass. The company also processed intermediate rare earth concentrates from existing stocks during the first three quarters of 2008. Molycorp Minerals LLC maintained production in the last quarter of the year. The mine at Mountain Pass has been closed since 1998. Future plans are to restart processing of stockpiled bastnäsite concentrates followed by reopening of the mine.

Jan 1, 2009

By C. Stacy

The mining industry is changing rapidly. Competition among OEM and aftermarket vendors increases dramatically each year as a result of mergers and acquisitions, and especially technology advancements in the mining industry. Adding value to mine operations by delivering technical value and differentiation is becoming more subtle and more difficult to accomplish. Because of this, identifying and protecting intellectual property has become more important to the product development, engineering and marketing/sales continuum than it had been in the past. How companies protect intellectual property and determine the value of those assets is critical to the sustainability and differentiation of technology providers in the mining industry.

Jan 1, 2012

By J. de Bakker

It hardly needs to be repeated that if coal is to continue as America’s premier source of cheap energy, it is absolutely necessary that the carbon dioxide from its combustion somehow be sequestered. A promising method proposed to accomplish this is the “indirect” carbonation of serpentine in a concentrated magnesium chloride brine. Indirect carbonation could be also applied to precipitate magnesium in lateritic nickel processing: this would not only solve magnesium-control problems in laterite hydrometallurgy, but also reduce its energy requirements and create CO2-sequestration credits. Fifty-five percent of the electricity generated in the United States comes from coal-fired power plants, and American coal reserves can last over 500 years at 1990-level consumption1. Coal is therefore both abundant and cheap: it could (and in fact probably will) continue to be an affordable source of energy, both for producing electricity and as a feedstock for liquid hydrocarbon production by Fischer-Tropsch reactions. As a result, it is important to find a workable method of permanently sequestering CO2.

Jan 1, 2007

By W. Miles

Introduction From a historical perspective, bentonite is the common rock term for various uses and applications. Its name originates from water-based muds near Fort Benton used for lubrication of wagon wheels during the 19th century migration to western territories (which are presently part of the United States) when the pioneers ran out of axle grease. From a clay mineralogy perspective, bentonite is composed primarily of montmorillonite, an expandable magnesium aluminum silicate clay mineral. When magnesium occupies an octahedral structural site that usually contains an aluminum atom, a negative charge is created. In order to neutralize negative charges, cations are drawn to the interlayer surfaces between clay mineral sheet structures. Modern applications for bentonite depend on the sodium or calcium cation populations and other characteristics of the clay mineral. When sodium is the dominant cation, the material is also called sodium bentonite, also known as swelling bentonite, western bentonite or Wyoming bentonite. When calcium or magnesium is the dominant cation, the material is called calcium bentonite, also known as nonswelling bentonite or southern bentonite. Swelling bentonite is recognized for its rapid hydration of interlayer sodium and subsequent dramatic expansion up to more than 20 times its original volume. Low shear can then disperse the hydrated sodium bentonite to form suspensions that increase viscosity and suspend solids. However, when shear is subsequently eliminated a sodium bentonite slurry gels. Characteristically, nonswelling calcium bentonite has relatively poor hydration properties and thus low expansion of the clay mineral. When subjected to low shear, calcium bentonite exhibits very little viscosity and poor suspension. Additionally, when shear is subsequently eliminated no more than minimal gelling takes place. The domestic and export markets related to both swelling and nonswelling bentonite are discussed below.

Jan 1, 2007

By D. L. Watson

In spite of the deflationary state of the minerals business today, there will be opportunities for those who can fulfill future needs. Since there are abundant supplies of ores and fuels to keep prices down, at least in peacetime scenarios, future needs may be as much political and social as technical and economic. Engineers and economists will develop new and innovative ways to find, mine, process and pay for mineral deposits. Pressure from governments and non-governmental organizations and the public will combine with market forces to provide opportunities for highly competitive, risk-taking enterprises who can leverage the qualities of their orebodies and employees by being good neighbors and partners.

Jan 1, 2000

Over 800 mines have closed in Australia in the past 25 years. This paper summarizes the data obtained from those closures and includes all Australian States and Territories and all commodities, including metalliferous, coal and industrial minerals. Twenty five percent of the mines closed due to resource exhaustion or depletion; 24% due to high costs, price drops, or declining grades; 8% due to open pit resource depletion (but with underground reserves remaining) or underground reserves depleted (but plans to open cut remainder) and 7% due to receivership or voluntary administration. The environmental, social and economic impacts of these closures are also significant and include acid mine drainage and impact on mine employees. An understanding of the causes of premature mine closure will better equip mining companies and governments to better manage future mine closures, wherever in the world the mines are operating.

Jan 1, 2007

By M. M. Botz

Cyanidation tailings which are disposed in a surface impoundment experience a loss of cyanide due to natural degradation, frequently reducing the cyanide concentration to very low levels. Quantifying cyanide losses in terms of pond geometry, local weather conditions and feed solution chemistry has been largely empirical though in many cases mining operations rely on surface impoundments to reduce cyanide to below an internally regulated concentration or an effluent limitation. To permit a more quantitative evaluation of cyanide losses in an impoundment, a computer simulation was developed to estimate the losses of free, WAD and total cyanide due to dissociation, photolysis and volatilization. Results of the model are compared against data collected for a North American tailings impoundment during 1998.

Jan 1, 1999

By T. W. Camm

Aristotle made the observation that man is a political animal. Engineers often like to think they are above the fray when it comes to organizational politics, but most organizational theorists believe politics is a fundamental dynamic in any group. This paper examines the various ways that people use power within organizations to negotiate the political interactions in the work place.

Feb 27, 2013

The residues produced during the incineration of leather scraps contain significant amount of chromium which can be recovered and reused in the tanning industry. The objective of this study is to develop a cost effective method for chromium recovery from leather ashes produced during the incineration of leather scraps using a fluidized bed incinerator. The entire process investigated involves fusion of leather ash with sodium carbonate in air to oxidise chromium to sodium chromate, leaching with distilled water to dissolve chromates, and chromium reduction from the hexavalent to trivalent state by sodium thiosulphate solution. The main factors affecting chromium extraction, such as temperature, reaction time, and sodium carbonate to leather ash ratio, were investigated. Based on the results obtained, almost 100% Cr extraction can be obtained at 700°C fusion temperature, sodium carbonate to ash weight ratio equal to 3 and retention time longer than 50 min.

Jan 1, 2006

By M. S. Fraley

As we compete for close margins in wholesale sales, the effects of both quality and price have a major impact on the cost of producing electricity.SO2 emission allowances have traded as low as$60/ton to as high as $215/ton over the last three years. This price spread in emission allowances clearly demonstrates the correlation between the quality of fuels versus the price utilities will be willing to pay for them. This paper provides an overview of the effects of the qualities of fuel, coupled with transportation as well as environmental concerns on the price of fuel and the ability to compete in a deregulated electric market.

Jan 1, 2000

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