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By J. B. Hedrick

In 2004, rare earths were not mined in the United States. The major supplier, Molycorp, continued to maintain a large stockpile of rare-earth concentrates and compounds. Major uses for these commodities were in automotive catalytic converters, petroleum fluid-cracking catalysts, permanent magnets, glass-polishing compounds, ceramics, metal-alloying additives, phosphors and rechargeable batteries. Consumption of refined rare-earth products decreased. The United States was a major importer and exporter of rare earths in 2004. Yttrium was not mined or refined in the United States in 2004. Imports from China, France and Japan accounted for most of the U.S. supply of yttrium compounds for refined yttrium products.

Jan 1, 2005

By D. W. Olson

Garnet has been used as a gemstone for centuries. However, garnet’s angular fractures, relatively high hardness and specific gravity, being chemically inert and non-toxic and free of crystalline silica, and its ability to be recycled make garnet ideal for many industrial applications. Garnet is the general name given to a group of

Jan 1, 2005

By Christian Maguire

The presence of hydrogen sulphide in sewerage systems leads to severe concrete corrosion. Acid causes breakdown of the concrete matrix, and attacks reinforcement. Older sewer systems under acid attack are often found to be acutely corroded, sometimes after short operational periods. Consequently secondary liners are now almost always used. Polymer concrete is extremely acid resistant and if used in segmental linings can forgo the need for a secondary lining. Combined with fibers and/or GFRP rebar Polymer Concrete can produce a very strong acid resistant lining, saving considerable time in the installation of additional liners. This paper explains the problems and advantages of using Polymer concrete in segmentaly lined wastewater tunnels, addressing areas of design, cost, and programming.

Jan 1, 2008

By Y. P. Chugh

Additional field evaluations of a modified continuous miner using a new spray system and modified scrubbers have been conducted by the authors. In this demonstration, a comprehensive package for dust control on a continuous miner which included previously developed modifications to the scrubber, scrubber intakes and the innovative chassis spray system was demonstrated. Side-by-side comparisons of the modified miner and regular miner indicated that the miner operator with the modified miner was exposed to 62% less respirable dust. Ram car operators with the modified miner had 38% less respirable dust exposure and the return air on the modified miner had 19% less respirable dust. The mining conditions during side-by-side testing were very comparable. These results support the findings of the modified spray system studies conducted earlier at different mines in Illinois on four occasions and the modified scrubber system field evaluation studies.

Jan 1, 2009

By J. O. Voigt

No major changes took place in the salt industry during 2004. No new uses of salt appeared and only localized supply disruptions occurred. Many salt producers reported slightly increased salt sales and profits for the year. In the United States, about half of the salt supply is produced as brine, by solution mining, and is used by the chemicals industry. One-third of U.S. salt is produced as rock salt by 14 underground mines. The remaining two production techniques, each with less than 10 percent of the total tonnage, are vacuum-pan-evaporation for refined, food-grade salt, and solar pond crystallized salt.

Jan 1, 2005

The National Institute for Occupational Safety and Health (NIOSH) conducted field tests to evaluate the effectiveness of a wet head continuous mining machine for reducing dust exposure for continuous miner operators. Wet head technology delivers water via sprays to the continuous miner?s cutter head as opposed to traditional standard sprays located on the boom and body of the mining machine. The sprays, positioned directly behind each bit on the cutterhead, deliver water at the point of attack, serving to cool the bits during mining to reduce the potential for frictional ignitions. The sprays also flood the coal with water to potentially suppress dust generation. Dust surveys were conducted at several mines to evaluate the wet head?s effectiveness to control respirable dust exposure at the continuous miner operator location and in the immediate return. Results show that the wet head miner generally improved air quality at both sampling locations to varying degrees in some, but not all, mines when compared to a continuous miner with a standard spray system.

Jan 1, 2010

By T. Hudaverdi

Several studies have been conducted on blastability and prediction of fragmentation. The term blastability is used to refer the susceptibility of the rock to blasting and is closely related to fragmentation. Parameters that determine fragmentation by blasting may be divided into two groups. The first group consists of blasting design parameters. The blast design parameters are controllable parameters and determined by the explosive engineers. The burden, spacing between holes, bench height, drillhole diameter, stemming height and explosive density are all design parameters. The second group consists of rock mass parameters that are referred to as uncontrollable parameters. The uncontrollable parameters are physical and mechanical properties of rock and rock mass structure. The strength, modulus of elasticity, density of rock, number of joint sets, joint orientation and joint spacing are among uncontrollable parameters. The rock mass parameters and blast design parameters should be considered together to explain fragmentation process. In this study, a blast database was accumulated to use for multivariate analysis. The blast database contains the blasts performed near Istanbul region quarries and the blasts that were preformed in various mines in the world by the blasting researchers. The cluster analysis was used to separate the blast data into different similarity groups. Group memberships were analyzed and checked by the discriminant analysis. Then, the multivariate regression analysis was used to develop a prediction equation for blast fragmentation for each group. Finally, a validation of the suggested models was performed for various mines. The model comprises blast design parameters, mechanical properties of rock and rock mass structure.

Jan 1, 2011

By Susan L. Bednarz

Recent advances in digital cameras and image processing allow photographers to produce excellent high-resolution action shots in low light and high contrast conditions commonly encountered underground. Digital photography is often used for construction and inspection documentation for underground structures. Designers, owners, and contractors benefit from quality photographs that document incremental progress and project milestones. Documentation photos serve as a lasting record of as-built conditions, are an important marketing tool, and help the owner build public support for expensive public works projects. When the project is complete, the only mementos that the participants will hold onto are the photographs.

Jan 1, 2008

By Thomas Sisley, Jozef Zurawski, Richard Switalski

Hilltop Interceptor Contract G is one of the segments of the wastewater control system in the greater Cleveland area. The tunnel is a relief interceptor constructed by the Northeast Ohio Regional Sewer District to minimize combined sewer overflows in the Easterly Service Area. The design study identified the need for a 3.35 m (132 in) diameter, 3.35 km (11,000 ft)in-line storage conveyance tunnel to be constructed at depths of 30 to 70 m (100 to 230 ft).Six structures for access, future flow drop, work shafts and overflow control were required to complete the system. The interceptor reduced the design peak flow from 12.5 m3/s(285 mgd) to 6.1 m3/s (140 mgd) by detaining in line 22,800 m3 (six million gallons) of wastewater.

Jan 1, 1997

Start with your assessment of the minerals business —domestic mining as well as operational and consulting perspectives. As a third generation miner, I have been living the mining business for as long as I can remember. I have watched commodity prices produce boom and bust cycles in places like Price, Utah (coal), Douglas, Arizona (copper) and Eureka, Nevada (gold). It is unsettling to see how our industry has fluctuated, but it always seems to rebound if you can stick out the down cycles. However, our most recent dip in the cycle was, in my opinion, characteristically and permanently different. In the past, when prices went south, people hunkered down and waited out the cycle until things came back, much the same as they had every other time. Not this time. This time, we saw a consolidation of the industry in proportions never seen before. Mega-mergers like Exxon-Mobil, Phelps Dodge-Cyprus and Newmont-Normandy have changed the complexion of our industry forever. And that is true not just of the mining companies; it happened across the supporting business lines as well. As a midsized niche engineering and environmental service provider to the mining industry, companies like mine are few and far between these days. The lean cycle saw many of the small and midsized providers get gobbled up by consulting giants like URS and TetraTech. The mentality of a mega-company, whether a commodity producer or a goods or service provider, is different than that of their small- and medium-sized counterparts.

Jan 1, 2005

By M. Moats

Copper electrowinning operations have dramatically improved their ability to produce high quality copper at low costs over the past several decades. Even so, some fundamental understandings are still lacking, which could allow operates to run more efficiently. For example, a rule of thumb exists that estimates a current efficiency loss of 2-3% per gram per liter of iron in the electrolyte. While several laboratory studies have been performed that demonstrate this rule of thumb is likely true, no definitive relationship exists. In this paper, the first steps in developing a definitive relationship are presented. The effective diffusivity of ferric ions in synthetic copper electrowinning solutions was measured using chronoamperometry and the Cottrell equation. The effective diffusivity of ferric ion was determined as a function of electrolyte concentration and temperature. Synthetic electrolytes were then used in laboratory scaled copper electrowinning experiments where relationships were found under stagnant conditions between current efficiency and solution composition.

Jan 1, 2009

By P. Burmeister, R. A. Errath, A. Sapin

Sag Mills are becoming bigger in size almost every year. Concentrator plants are also becoming larger with more SAG and Ball Mills units with Gearless Mill drives installed in one plant. In contradiction to this development, concentrator plants are being built in increasingly remote areas, where the power supply and network conditions are not necessarily covering the needs for the operation of such plants. This paper describes sources of harmonic distortions and possible approaches to solve this problem. It also illustrates the permissible tolerances in terms of commutation of power electronics, based on already realized installations. Furthermore it explains how, and with which measures, harmonic currents created by non-linear loads with SAG and Ball Mill drives can be handled, and how harmonic standards can be fulfilled accordingly. Finally, this paper gives an overview about the technical impact of a strong versus weak network, and the economic relationship between them.

Jan 1, 2001

By S. M. Jasinski

Peat is a natural organic material of botanical origin. Peatlands are situated predominately in shallow wetland areas of the Northern Hemisphere. Commercial deposits are formed from the gradual decomposition of plant matter under anaerobic conditions for about 5,000-years. In 2004, peat was harvested in 16 states. Florida, Michigan and Minnesota accounted for more than 80 percent of the U.S. production. Reed-sedge was the dominant variety of peat harvested in the United States, comprising almost 80 percent of the output. This was followed by humus, hypnum moss and sphagnum moss.

Jan 1, 2005

By Russell Barr

Strategic alignment throughout a mining organization is critical to effective strategic execution and good business performance. The alignment of strategic goals and objectives in the different operations and functions in a large global operation is a challenge facing executive management in light of legacy organizational structure and processes. An additional confounding factor in strategic alignment of acquisition and new project expansion is that mining projects and operations are frequently multi-cultural in terms of country origin as well as organizational culture. This brings together many cultures to accomplish the project or complete an acquisition (Financial Times, 2006). The mining industry presents numerous challenges to executives and mine management by the nature of the operation and organizational processes used in running it. For example, there seems to be an inherent conflict between the individual goals of the components that constitute a mineral processing operation (the mine, the mill, the smelter and the refinery), and lowest cost production of the final product. Managers of these component operations have specific objectives passed down from the corporate executives. Those site managers tend to be compensated based on throughput and perform to this main metric. This tendency to maximize throughput for an individual operation can contradict the general process flow of a best-fit solution to producing the final product at the lowest cost. In an effort to become more aligned, firms are increasingly using balanced scorecard derivatives at great cost and effort (whether internally or externally sourced) in an attempt to help with strategic alignment. Balanced score-cards have been effective in providing a good strategic scorecard to companies with some measure of strategic alignment. Many firms make this effort of using balanced scorecards. However, most firms are not strategically aligned or, at best, are sub-optimized, in terms of strategic alignment (Kaplan and Norton, 2006). The tendency in mining operations is to focus on operating individual components as optimally as possible and stretching existing assets to the best possible production rates. ?Making tons? is the common operational focus. Numerous factors underpin this focus and can affect the ability of the operation?s ability to align properly with the corporate strategy and strategic goals. Critical factors are legacy organizational structure, culture, processes and performance measurement systems. Changing anyone of these factors to affect better strategic alignment requires significant attention to managing change.

Jan 1, 2008

By J. A. Ober

China, Mexico, Spain and Turkey are the leading producers of celestite (strontium sulfate), the most common strontium mineral. Of an estimated 510 kt (562,000 st) of celestite produced worldwide during 2004, 98 percent was produced in those countries. Deposits of strontianite (strontium carbonate), another strontium mineral, have been identified in China and Malawi. Relatively small quantities are reported from the deposit in China. Although celestite deposits occur in the United States, no domestic celestite has been mined since 1959.

Jan 1, 2005

At present, discounted cash flow analysis is generally accepted as the preferred method of valuation of mine projects in surface coal mining. One of the major reasons for that is its ability to take into account the time effect of money over the life-of-mine. As a looking-forward method, it requires forecasts be made with regard to economic, technological, technical, geological, and environmental conditions that will prevail in the future. All forecasts are inherently uncertain as they are a function of the uncertainty of all variables of the discounted cash flows analysis. This indicates that the only alternative for modeling the uncertainty in the project evaluation is the development of adequate risk models to serve the decision-making process. The paper offers a model of project cash flows at risk in strip coal mining, which is an integrated corporate risk management solution. The model is based on a stochastic approach that provides the answer to the question about how large is the deviation between stochastic cash flows and the planned value (or that used in the budget) at each time step of the discounted cash flows analysis, that is due to the uncertainty in the model variables. A solution is worked out for the allowable range of the stochastic cash flows variation that determines the probability of achieving the planned value of a mine project. The Monte Carlo simulation technique is used to model the stochastic behavior of the project variables. A case study of an opencast coal mine project is provided to illustrate the applicability of the risk model. The results obtained provide a new understanding of the mine project risk as a component of the project discount rate.

Jan 1, 2006

By L. Tercero Espinoza, F. Marscheider-Weidemann, C. Gandenberger

"A reliable supply of non-energy raw materials is a precondition for the functioning of the European economy. In line with its importance, the issue of raw materials supply has become more prominent in the past years, especially owing to turbulent raw material markets. However, these turbulences are not due to depletion of the geological resources but to a missmatch of (expected) supply and (expected) demand, with several interacting factors influencing the markets both from the supply as well as from the demand side. A recent evaluation, published in June 2010 within the framework of the EU Raw Materials Initiative, sought to bring together these two sides of raw material markets and asked the question "which raw materials are critical for the EU?" Herein we present the methodology used by the Ad-hoc Working Group on Defining Critical Raw Materials and the results obtained, complemented by results from the study "Raw Materials for Emerging Technologies"."

Jan 1, 2011

By Kerry Spickelmier

The only nickel smelter and the only active nickel mine in the United States is Glenbrook Nickel Co., a joint venture (50% each) of Cominco Resources International Ltd. and Cominco Ltd. In 1989, with the nickel price riding high between $2.30 and $2.70/kg ($5 and $6/lb), Glenbrook seized the opportunity to purchase and recommission a southwestern Oregon ferronickel smelter and the adjacent nickel-ore mine. This Douglas County site is only about 97 km (60 miles) due east of the Pacific Ocean, and California's border lies a similar distance to the south. Hanna Mining Co. had closed the operation in 1987. And the following year, the equipment had been largely stripped for salvage value. From November 1990 through August 1992, the mine supplied an average 5 kt/d (5500 wet stpd) of ore. Currently, with import ore supplying 40% of the smelter feed, the mine's daily tonnage averages 4.2 kt (4600 wet st). From November 1990 through August 1993, the mine has delivered 2.1 Mt (2.3 million st) of ore grading 1.22% nickel with an average moisture content of 26%. Buffaloed nickel? A nickel is not worth what it was in 1989 and neither is ferronickel, with recent prices hovering around $1.13/kg ($2.50/lb). To survive, Glenbrook has focused on increasing smelter production to lower its operating costs. And this strategy has triggered several bold moves: • a new, $30 million, port facility and • a 10-year importation contract for ore from New Caledonia, an island approximately 1000 km (625 miles) east of Australia. For a Glenbrook update, a May 25, 1993 visit was made to the company's Oregon operations - the mine and smelter near Riddle plus its new Coos Bay port facility. Unfortunately, as the rain came down that day, so did news of another temporary shutdown. The previous suspension had lasted from Dec. 20, 1992 until Feb. 22, 1993. Barely three months back to work on a wet May afternoon, more than 250 of Glenbrook's approximately 300 employees contemplated yet another shutdown, effective July 31, 1993.

Jan 1, 1993

By Ken Goering, Steve Kral, William Gleason

"Once every four years, the global mining industry gathers in Las Vegas, NV for MINExpo International. According to the show’s organizer, The National Mining Association (NMA), about 44,000 people attended the three-day show from Sept. 26-29. It was a show that featured the latest and greatest in equipment and technology. It also served as the backdrop for a snapshot of the state of the industry and while the picture of a global industry is never completely clear at any one time, one thing that is evident is technology has become a major force in the way mining is done.Had it not been for the awe-inspiring “iron” that was on the show floor in the form of haul trucks and shovels weighing hundreds of tons, one could be forgiven for thinking that they were at the Consumer Electronics Show. From training simulators designed to give a realistic experience of operating mining equipment to virtual reality technology that can take the user into the depths of an underground mine or the middle of a mapped ore deposit, an overriding theme of MINExpo 2016 was that the mining industry is connected like never before.In the north hall of the Las Vegas Convention Center was the GE Mining booth that was designed to showcase its efforts to help create a mine that will be connected from the front office to the face of the underground wall or bottom of the openpit. GE Mining called its booth a digital mine, and it included a suite of technologies that can improve performance, reliability, safety and operations. GE Mining said it views each mine as a mini-city, requiring power, water and transportation. Intelligent, real-time monitoring across the mine allows operators to make data-driven decisions that improve equipment reliability and optimize mine operations for substantial savings. And GE Mining was just one of many exhibitors showing off software that allows various types of equipment to communicate. Its booth sat in the shadow of the Komatsu booth with its new 360-t (400-st) 980E-4 haul truck that included GE’s 360-t (400-st) electric wheel motor. This is just one example of how technology is connecting machines, operations and people around the world and how mining is moving forward."

Dec 1, 2016

By L. A. Ruth

Vision 21 is a government/industry/academia cost-shared partnership to develop the technology basis for integrated energy plants that will, early in the 21stcentury, result in the deployment of ultra-clean plants that produce electricity and “opportunity” products. Vision 21 plants will use fossil fuel feed-stocks in combination with other domestic resources, e.g., biomass, municipal waste, and petroleum coke. Opportunity products could include transportation fuels, steam, high-value chemicals, synthesis gas, and hydrogen. Performance targets for Vision 21 plants, example plant configurations, and the key technologies that will be needed are described.

Jan 1, 2000