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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 Jr. Matthews

The Candelaria copper-gold deposit is located in Region m of Chile, 805 kilometers north of the capital, Santiago. Candelaria was discovered in 1987, following a six month exploration program. In late 1986, induced polarization (IP) surveys outlined an anomalously high response within the area of interest. The first test hole bad three intersections totaling 49 meters, with an average grade of 1.97% copper. Drilling eventually outlined approximately 390 million tonnes, grading 1.09010 copper and 0.26 grams/tonne gold. Production began in early 1995 and is estimated at 120,000 tonnes copper and 80,000 ounces gold annually.

Jan 1, 1996

By Jack T. Work

Spiraling costs in every segment of the open-pit mining cycle is a fact of life that every operator must reckon with. The introduction of various shock absorbing devices for rotary drilling is one recent innovation that may significantly reduce overall drilling cost, increase drill availability, and lower maintenance requirements. In a recent all-inclusive test in taconite ores, shock absorbers on Bucyrus-Erie BE 60R and Gardner¬Denver GD 120 rotary drills were directly responsible for overall savings of up to $41.06 per hour. What is It? A shock absorber is simply a device installed between the rotary drive head and drill steel that cushions the two. It functions in the same manner as springs and shocks on an automobile. Some benefits associated with use of the tool are readily apparent on a daily basis; other benefits are realized over longer time intervals and through continued use. A properly designed shock absorber will: •protect the drill from severe vi¬brations, improve rock bit performance, allow application of the best weight-on-bit and rotating speed under all drilling conditions, •function effectively over a wide range of applied bit weights, • have a spring rate soft enough to perform its primary function of absorbing both rotary and vertical vibrational forces generated by rough drilling, •be reliable and subject to as little maintenance as possible, •be easy to install and remove, and • be of such an economic benefit so as to offset the added expense of its application. A shock absorbing tool developed by BJ-Hughes Inc. was used in a recent test. The "Smoothdrill" is just one of the products currently available. This unit absorbs both rotary and vertical shock loads and has no mechanical parts so lubrication is unnecessary. A rebuild of the unit consists of removing the worn rubber element and inserting a new element, an operation taking less than one hour. Minimizing Vibrations Severe vibrations on a blasthole drill operating in broken and discontinuous formations have visible effects. These vibrations often cause structural damage when allowed to' continue, resulting in fatigue cracks in the mast and related structural components in the drill. When rough running formations are encountered, drilling must be interrupted and possibly shut down. Usually, the drill operator resumes drilling using less down pressures and various rotational speeds until firmer drilling is encountered. An effective shock absorber can substantially reduce these vibrational forces so more down pressure can be applied in bad ground. It is generally accepted that longitudinal vibrations and cyclic forces are more effectively reduced if a tool is designed to incorporate a relatively "soft" shock absorber. The softness of any shock absorbing tool is best judged by its spring rate-the weight required to produce a given amount of deflection, commonly expressed in units of kg per mm or pounds per inch of deflection. All shock tools use a resilient member such as rubber springs, steel springs, fluid, or gas springs to absorb

Jan 4, 1980

Waste areas of a mine should be sealed especially if there is a risk of spontaneous combustion. Leakage through and around such seals can be problematic. Pressure balancing has been one of the favored options to prevent the ingress of air into these waste areas. Balance chambers require maintenance and monitoring to ensure that they are effective. This paper explores the use of inert gas as a means of controlling ingress of air and egress of waste gases as a means of reducing leakage around seals.

Jan 1, 2009

By John E. Shively, Tracy K. Lundin, Francis Fong

The Superconducting Super Collider (SSC) features two 20 TeV counter rotating proton beams which will be housed in 87 km (54 miles) of tunnel. Four additional lower energy particle accelerators will be housed in 26 km (16 miles) of tunnel and underground structures. Physics experiments will be conducted in two underground detector halls approximately 67 m (220 feet) deep with footprints measuring about 30 m (100 feet) by 100 m (330 feet). Definition and design of underground facilities is advanced with construction of approximately one-third of the SSC program underway. This paper presents an overview and status of the SSC project.

Jan 1, 1993

By R. Frim, S. D. Ukeles

The present U.S. production of bromine is from inland brines located in Arkansas and Michigan. The most concentrated domestic brines (up to 5,000 ppm bromide)are situated in Arkansas. Less concentrated brines(about 2,500 ppm bromide) are located in Michigan. The amount of bromine sold or used in the United States came from three companies operating in those two states. Its value was $191 million. In 2004, the estimated U.S. bromine production was 222 kt (244,000 st). That compared with 216 kt (238,000st) produced in 2003.

Jan 1, 2005

By S. Gaillard, E. Cauda

"Diesel particulate matter (DPM) is an occupational health hazard in underground mines. It generally occurs in the submicron range, and is often present in the mine atmosphere with significant concentrations of dust particles that tend to occur in the supramicron range. Since dust can interfere with analytical methods to measure DPM, it is often removed from a sample stream using impactor-type size selector (diesel particulate matter impactor, DPMI). Because the DPMI physically removes oversized particles from the stream, its performance may be gradually reduced with aging. Sharp-cut cyclones (SCCs) represent an alternative size selector for DPM sampling applications, with a major advantage being that, by design, they should not be susceptible to rapid aging. This paper presents results of a field study designed to compare the performance of aged versus new/clean DPMIs and SCCs in an underground mine. DPMI aging resulted in clogging of the device, and eventually a reduction of its effective particle cut size – though, when sample flow rate was maintained, DPM sample mass collection was not affected until significant aging had occurred. Under the conditions present for this study, effects of SCC aging were observed to be minimal by the end of the study period. INTRODUCTION Submicron particles are increasingly recognized as significant respiratory health hazards (Cantrell and Watts, 1997; Kenny, et al., 2000; Ristovski, et al., 2012). Diesel particulate matter (DPM) represents a major source of submicron particles in both public and occupational environments (Kittleson, 1998; Abdul-Khalek et al., 1998). Due to their work around large equipment in confined spaces, underground miners have some of the highest exposures to DPM (EPA, 2002; Grau et al., 2004). DPM largely consists of solid elemental carbon (EC), commonly known as “soot”, and organic carbon (OC) that may be sorbed to EC particles (Kittleson, 1998; Abdul-Khalek et al., 1998). EC and OC can be measured by thermal-optical methods such as the NIOSH 5040 Standard Method (Birch, 2016), and their sum is referred to as total carbon (TC). While the complex nature of DPM does not allow for its direct measurement, both TC and EC have been accepted as suitable surrogates for monitoring occupational exposures to DPM (Noll et al., 2007 and Birch, 2016)."

Jan 1, 2018

By Y. V. Swamy, B. Bhoi, H. S. Ray

Low-grade manganese ores with low Mn/Fe ratios can he enriched through selective carbon reduction of iron oxide to magnetite followed by magnetic separation o f the magnetite. Thermogravimetric analysis (TGA) was used to assess the preferential isothermal reduction of pure M1702 and Fe2O3 using solid carbon. This was followed by reduction of a synthetic analogue of composition comparable to an actual low-grade ore (i.e., Sandur manganese ore, Sandur, India). The carbothermic reduction of the manganese ore converts the hematite and goethite minerals to magnetite (Fe3O4), with the magnetite then going into the magnetic, fraction. The resultant nonmagnetic ,fraction becomes depleted of iron with an enhanced manganese content. These results show that it is possible to reduce the iron from 22% to 5.85%, thus increasing the Mn/Fe ratio from 1.52 to 6.2 with a manganese recovery of about 50%. The recovery was, further improved by grinding the magnetic fraction to -75 µm.

Jan 1, 1999

By S. Mischler, J. Noll, G. Schnakenberg, A. Bugarski, M. Crum

Diesel particulate filter (DPF) systems and biodiesel fuels are two of the most promising technologies available to the mining industry to reduce the exposure of underground miners to diesel particulate matter (DPM). A study has been conducted to estimate the potential of DPF systems and biodiesel blends to reduce DPM emissions from production vehicles. Results of testing three DPF systems in an isolated zone showed 88% to 99% reductions in elemental carbon concentrations. The test results also show that biodiesel blends, B20 and B50, reduced the elemental carbon concentrations in the mine air by 26 and 48 percent, respectively.

Jan 1, 2004

By Ronald J. Riberich

The Mineral Economics and Management Society (MEMS) held its fifth annual conference in Montreal, Quebec, Canada earlier this year. “The Minerals Industry: Responding to the Global Challenge” was the first MEMS conference to be held outside of the United States. About 125 mining- and minerals-related professionals attended. The MEMS program included six sessions and three distinguished speaker addresses. The session topics included: “Minerals in the Macro economy: Development in Demand,” “Trends in Global Metals Supply: The Producers’ Challenge,” “Global Environmental Issues: Policy Perspectives,” “Global Environmental Issues: Quantitative Analysis” and “Minerals in the CIS: Phoenix or Albatross?” A student session was also offered. It provided a competition for monetary awards for outstanding papers.

Jan 1, 1996

By David Kwietnewski

Roadheaders are gaining widespread acceptance in North America as a means for mechanical tunnel excavation. Until recently, almost all of the large-scale North American tunnel projects were excavated one of two ways ? the tried and true drill-and-blast method or with the use of tunnel boring machines (TBM), the hi-tech super-excavators. TBMs enjoyed fast-growing popularity worldwide as TBM manufacturers offered greater technology to meet the demand of the civil tunnel industry in the late 20th century. Recently, though, more tunnel projects, large and small, can thank the brute force of a roadheader for getting the job done.

Jan 1, 2011

By Colin Lawrence

The Port of New York and New Jersey is one of the most heavily used transportation arteries in the world, handling nearly 40 per-cent of the North Atlantic shipping trade and directly providing nearly 230,000 jobs to the local economy. In 2004, $100 billion worth of consumer goods moved through the port. To accommodate future cargo volumes in the port, which are expected to double over the next decade and possibly quadruple in 40 years, deeper shipping channels are needed to provide access for a new generation of cargo mega-ships with drafts exceeding 13.7-m (45-ft) when loaded. Current channels within the harbor range in depths up to 13.7-m (45-ft), thus preventing carriers from using these larger ships, or requiring significant reductions in cargo to achieve lesser drafts to operate safely within the harbor. As part of the Harbor Deepening Project, the Anchor-age Channel would be deepened to 15.2 m (50 ft) below mean low water (MLW), for a length of 5,790 m (19,000 ft). The New York City Department of Environmental Protection (NYCDEP) owns, operates and maintains two existing water siphons in the harbor. Due to their shallow depth, both existing siphons must be relocated before dredging of the Anchorage Channel can be completed. Tom Costanzo, manager of capital programs for the Port Authority of New York and New Jersey (PANYNJ), says that ?While the re-location of the existing siphons under the Anchorage Channel is vital to the success of the deepening program, it is also a story of cooperation among key agencies at different levels of government resulting in improvements that will benefit the people of this region greatly.?

Jun 1, 2010

Obtaining financing for mining and exploration projects has been difficult for the last several years, particularly for junior companies. Today, though, the purse strings of investors appear to be loosening, leaving the industry with many questions about financing in the coming years. How have capital markets and exploration spending changed? Are there signs of improvement? Where has capital been raised in private, public markets, stock exchanges, private equity, etc.? What companies successfully raised capital in the last year? How are they spending it? How are traditional and alternative funding sources investing in mining? What are the issues mining companies need to know about when tapping alternative sources of capital? Those were some of the questions that were answered at the Current Trends in Mining Finance conference, sponsored by SME and the New York Section April 26-28. Held in New York City, the conference attracted 115 professionals who work on the finance and economic side of the mining industry. Three of the conference organizers talked with Mining Engineering about the conference and the state of financing in the industry today. Tim Alch (TA) is managing director with Behre Dolbear & Co. Alan Oshiki (AO) is executive vice president with the Abernathy MacGregor Group. Henry Weingarten (HW) is managing director with the Astrologers Fund Inc. Here is what they had to say.

By Edmond J. O’Donovan

South Bulga is a new longwall operation located in the Hunter Valley coal-mining region in Southeastern Australia. The mine’s objective is to achieve productivity levels significantly higher than the current industry average. From the day longwall production began, South Bulga’s output was below both budget and industry expectations, primarily because of the poor performance of the conveyor system. In the past, conveyor systems have been seen as an adjunct to the mine plan, not as an integral part. At past production levels, this approach may have been acceptable. In today’s mining operations, the conveyor system must be treated as integral and vital to the mining operation. The conveyor system is analogous to the vascular or circulatory system of the human body. Of itself, the system does not do anything, but if it is not functioning satisfactorily, the mine cannot operate.

Jan 1, 1996

By Francois E. Heuze

Excavation of large rock caverns is a stepwise process. Whether one uses a heading and bench method or a multiple drift system, the use of excavation steps enables one to introduce the reinforcement, such as bolts or shotcrete, at the earliest possible stage. Knowing the spatial distribution and properties of rock materials and geological discontinuities, the cavern geometry and its reinforcement must be optimized. The finite element method of analysis is a powerful tool for such optimization. However, the models are only as good as their ability to account realistically for the physical attributes of the prototype and for the excavation sequence. They must include the following: - ability to model an incremental construction process. Thus requires the use of "Restart" procedures where displacements and stresses from a previous equilibrium are saved for the next step. - ability to model non-linear rock material behavior; in particular, the post-peak behavior of the rock which retains a residual strength when con-fined. The stability of many under-ground structures rests with the "broken" rock carrying significant loads. - ability to account for the non-linear behavior of geological discontinuities. These are two-fold. First, up to peak, non smooth rock joints will dilate. In a confined situation, dilation will increase joint strength by a consider-able amount (Obert, et al, Brady, 1971, Heuze,1978a), Then, beyond the peak, the joint also retains residual strength.

Jan 1, 1978

By Angelina Anani, Nilufer K. B. Akbulut, Sefiu O. Adewuyi

Crucial information about safety, design and operation from ground movement data can be utilized in underground mines. Communicating the information and exploring new findings can be a challenge, however, in a decade where there is an ever-increasing volume and velocity of data due to advancements in mining technologies. This challenge escalates for geotechnical data as they are multidimensional, depending on the space and the rate at which they take place. To tackle this challenge, geotechnical engineers should focus on using simple yet compelling visualization of rock mass data in 3D. Competent visualizations of ground conditions as a trigger action and response plan (TARP) could ease the communication of safety concerns and the exploration of rock mass displacement and strain surrounding an opening at an underground mine. Therefore, this study focuses on using scientific visualization methods by rendering geotechnical data over the surface of a 3D mesh model to display TARP levels. The study was conducted at the East Decline of the San Xavier (SX) Underground Mine, a laboratory mine operated by the University of Arizona. The project aims to produce visualizations that optimize the use of geotechnical data in near-real time.

Sep 1, 2025

By S. Mishra, C. Shon, D. Saylak

Only 40% of fly ash generated by the power plants in US are recycled and used for commercial applications. Of these, the high lime, Class C ash had been preferred. Systematic laboratory and field-scale studies have shown that, by including calcium chloride in the mix design of stabilization of roadbed materials, both Class C and Class F fly ashes can be effectively utilized. Test data reveal that the addition of calcium chloride to the system accelerates its curing rate, thereby increasing early strength and long term durability of the constructed road. For road construction, a preblended Class F fly ash–CaCl2 system tends to be more forgiving than the Class C fly ash–CaCl2 system. The former system produces more durable roads. The role of calcium chloride as an accelerator in these systems is discussed along with a mathematical model developed for fly ash- CaCl2 stabilized roadbed systems.

Jan 1, 2007

By O. B. Bucklen

The Coal Research Bureau of the School of Mines at West Virginia University, using a modified design of a Russian flotation device, was able to obtain a clean coal product containing 7.64 percent ash with 94 percent yield and 97 percent coal recovery. This favorable performance was obtained with the semi-pilot scale flotation cell operating as a simulated three stage unit on slurry taken from the fine coal circuit of a coal preparation plant. This experimental device, consisting of a sheet metal cyclone-like unit mounted on a U-shaped uplift pipe, uses a combined flotation and cyclone action to beneficiate the minus 14 mesh partially cleaned feed product. In addition to providing comparable analytical results, the airlift-cyclone possesses other attractive features among them being a low capital expenditure, utilization of moderate plant floor space, efficient "operation on high density feed slurry, and absence of moving parts.

Jan 1, 1964

By J. S. Limb

Actual issues which arose during the discovery process or subsequent court testimony are presented. While most of these issues relate to the author’s specialty of mineral appraisal some are more general in nature and could be of interest to those who may be involved in current or future court testimony. Several important areas to be reviewed and agreed upon with the client and their legal counsel are discussed. General observations on litigation, the discovery process, testimony and some repercussion’s are also given.

Jan 1, 2001

By Wayne Hilgedick

Peabody Coal Company is the nation's largest producer of coal and is headquartered in St. Louis, Missouri. In 1978 Peabody divisionalized its operations to establish more responsive and effective mine management. Peabody Coal Company's Arizona Division operates two large surface mines, the Black Mesa and Kayenta Mines. Both are located in northeastern Arizona, approximately 30 miles from Kayenta, Arizona, on the Navajo and Hopi Indian Reservations. The Black Mesa Mine produces 4 to 5 million tons of coal per year and the Kayenta Mine produces 7 to 8 million tons per year. Coal from the Black Mesa Mine is transported 274 miles by coal slurry pipeline to the Mohave Generating Plant located on the Nevada/Arizona border at Bullhead City, Arizona. This plant is jointly owned by Southern California Edison, the Los Angeles Department of Water and Power, Nevada Power Company and Salt River Project Agriculture Improvement and Power District.

Jan 1, 1983