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By Manuel Arnáiz, Pedro R. Sola, Rogelio Baudot, Manuel Herrera, Carlos S. Oteo

The aim of this paper is to describe and analyze the ground treatment performed between January and May 2002 in order to increase safety during excavation and reduce instability problems along 180 m of tunnel, during the construction works associated with line 10 extension to the Madrid Metro. The tunnel was excavated using the traditional Madrid Method and in the section considered in this paper layers of sand were detected around the tunnel crown area with a significant presence of water, the in?ow of which needed to be controlled with a minimum impact on the surrounding environment.

Jan 1, 2003

By Michael Gilbert

In the world of tunneling the glamour is in the large diameter, long tunnels, but perhaps the number of projects for small diameter and short length tunnels are greater and generally have higher risk factors. Reasons for these higher risks include both the ?boiler plate? contract provisions used on these types of contracts, the technical specifications related to the tunnel work (versus the pipeline construction), the bid practices including measurement and payment and the construction. This paper reviews and comments on some of the key issues the authors have observed in recent major pipe-line projects that involve a small percentage of tunneling footage of the total contract.

By M. S. Klima, V. Choudhry

Coal gasification solid residue (slag) contains unconverted carbon (char) which is considered an impurity for utilization applications of slag. Under this study, table concentration was used to process approximately 24,000 pounds of a nominal -3.4 mm gasifier slag (~85% ash) to separate high (~100%) ash slag from low (~50%) ash char. The results indicated a nearly ideal separation of the slag from the char for sizes coarser than about 1 mm. An overall slag yield of 71% was obtained. The slag was sufficiently clean to be used as feed material for the production of expanded lightweight aggregate. The recovered char had an ash content of about 47% and was a nominal -1 mm in size.

Feb 24, 1997

By D. Hopkins, D. Türler, R. D. Giauque, W. B. Davis, M. Karaca

In a highly collaborative research and development project with mining and university partners, sensors and data-analysis tools are being developed for rock-mass characterization and real-time measurement of mineral content. Determining mineralogy prior to mucking in an open-pit mine is important for routing the material to the appropriate processing stream. A possible alternative to lab assay of dust and cuttings obtained from drill holes is continuous on-line sampling and real-time x-ray fluorescence (XRF) spectroscopy. Results presented demonstrate that statistical analyses combined with XRF data can be employed to identify minerals and, possibly, different rock types. The objective is to create a detailed three-dimensional mineralogical map in real time that would improve downstream process efficiency.

Jan 1, 2002

By F. V. Antonio, R. S. Pizarro

Masbate Gold Mines, dormant since WWI I, are now back in operation. The ore treatment plant incorporates carbon-in-pulp processing, utilized because of the ready availability of coconut shell charcoal in the Philippines and the high clay content of the ore. A detailed description of the plant, including the surprisingly fast and efficient alcohol stripping facility is presented. Operating data for the plant is provided together with an interesting performance evaluation of mechanical versus air- lift agitated leach tanks.

Jan 1, 1981

By Frank P. Frandina, Diane R. Hirsch, David P. Field, Colin R. Weeks

To accommodate growth in air service and to follow the Master Plan for long-term airport development, the Metropolitan Washington Airports Authority established thed2 Development Program at Washington Dulles International Airport. A sub-surface Automated People Mover (APM) System is under construction to replace the Mobile Lounges as the primary people mover system at Dulles. To minimize disruption to airport operations the majority of the APM System’s crossings of Taxi lanes will be undertaken using Tunnel Boring Machines (TBM) or the New Austrian Tunneling Method (NATM). This paper explores the planning and design of these shallow tunnel segments for future generation aircraft loads, within the constraints of minimal construction access under post 9/11 security requirements and the context of the overall airport expansion program.

Jan 1, 2005

By W. J. Miles

At the beginning of the 20th century, barite was a mineral of minor importance in the USA. Its primary use was to extend lead oxide in white paint. Barite also added the special qualities of hiding power and flatness to paint. Because white lead sometimes turns black or yellow and barite does not, ground barite became a pigment on its own merit. Barium chloride was added to bricks before firing to stop efflorescence when exposed to weather. Barium carbonate or nitrate added luster and brilliance to glass. Barium chemicals were added to refining sugar, enameling iron, making oilcloths and paper collars, and in the manufacture of paper, artificial ivory, rubber and lithopone. Lithopone became a major paint ingredient in the 1920s; its use lasted until the 1950s, peaking at 150,000 metric tons of barite in both 1937 and 1947 for the manufacture of lithopone. Later in the 20th century, titanium dioxide replaced lead oxide, barite and zinc oxide in the coatings industry. In the 21st century, barite is used as a filler, extender, or weighting agent in products such as paints, plastics, and rubber. Some specific uses include its use in brake and clutch pads for automobiles, automobile paint primer for metal protection and gloss, add weight to rubber mud flaps on trucks, and add weight to the cement jacket around petroleum pipelines under water. In the metals casting industry, barite is part of mold release compounds. Because barite significantly blocks X-ray and gamma ray emissions, it is used as aggregate in high density concrete for radiation shielding around x-ray units in hospitals, nuclear power plants, and university nuclear research facilities. Ultra-pure barite consumed as liquid is used as a contrast medium in medical X-ray examinations. Barite is the raw material for barium chemicals, such as barium carbonate, which is an ingredient in faceplate glass in the cathode-ray tubes of televisions and computer monitors. In the 21st century, barite industrial uses account for an estimated 78,000 tons per year in the United States. Another barite use was patented in 1926 by the oil industry. In this patent, barite is primarily used as a non-abrasive weighting agent for drilling for oil and gas exploration and production. As a weighting agent, it provides the downward force in a water based or oil based drilling fluid for cutting through rock with a tri-cone diamond drill bit. In order to minimize the wear on the drill bit and drill stem, minimum abrasion of the weighting agent is preferred. In recent years in the USA, 95% of the barite produced and about 80% on a world basis are used as a fluid weighting material during the search for oil and gas. During the latter part of the 20th century, barite was used in the drilling mud of oil and gas wells, particularly for wells deeper than 2000 meters, and petroleum well drilling demand for barite became the mineral?s major end use during economic expansions after World War II and subsequent increased use of oil and gas in the USA. The profitability of oil and gas production had a strong effect on the number of drill rigs and consumption of barite. The United States was the leading petroleum well drilling country starting in 1970, reaching 4,530 drill rigs in December 1981, and was the largest consumer of barite. In the USA, record highs of about 2.6 million tons of barite produced and 4.3 million tons consumed were reported in 1981. From 1997 to 2006, barite production declined from 662,000 to 589,000 metric tons. However, USA imports increased from 1,470,000 to 2,530,000 metric tons for lump barite. World production of barite increased from 6,780,000 to 7,960,000 metric tons during the same period. Table 1 (see Appendix) lists USA production, imports and exports and world production from 1997 to 2006. Major sources of imported barite include China, India and Morocco. Table 2 (see Appendix) lists the USA imports and price of barite by country. China, India and Morocco are the three largest exporters of barite to the USA and the world. Vietnam is a new producer, beginning in 2006. IMPACT OF CHINA ON DRILLING GRADE BARITE In the 1970s or before, China began supplying barite to the world drilling market in order to help develop their economy. When China first entered the barite export market, their high production volume, low pricing and low ocean transport expenses to the Gulf Coast forced barite producers in the USA to supply only regional markets, such as Battle Mountain Nevada barite for the western and Rocky Mountain states and Canada. Until recently, it was China?s government policy for domestic consumers to use barite below the API 4.20 specific gravity specification, leaving higher grades for export, but this is no longer the case. In recent years the internal demand for barite in China increased tremendously as their economy rapidly developed. China reduced their former 15% VAT tax rebates to 5% for Chinese barite producers, and then eliminated all VAT tax rebates on December 15, 2006. On the supply side, some high-grade barite deposits in China have been depleted. In particular, the low heavy metals sources are less plentiful. Additional mine capacity is being developed, but the new mines are underground and therefore costs will be higher. China?s appetite for other raw materials has tied up a large portion of the world?s bulk vessel fleet, including Panamax vessels (preferred for barite ore transport). Ocean transport freight rates have increased in recent years, and receiving ports in the USA are congested with imports of higher-added-value products. The Panamax Index, which tracks maritime shipping rates, more than doubled in 2006. China has also devalued its currency from RMB8.30 to RMB7.80 per dollar. These factors are driving up the import price of crude and ground barite for drilling. In addition, in the USA, rail congestion and high fuel prices led to higher trucking rates, increasing the delivered cost of ground barite to oil customers. India is the second largest supplier of crude barite to the USA and world drilling market. It produces all of its barite from a single deposit in the Cuddapah region of Andhra Pradesh State. More than 90% of production comes from the State-owned Andhra Pradesh Mineral Development Corp., and the government continues to closely control production, export volumes, and prices. India saw a dramatic increase in barite prices as a result of its last 3-year tender in 2004. However, in 2004 and 2005 their shipments of crude barite to the USA were not significant. In 2005, India began supplying barite pulverized to meet API specifications to the Gulf Coast. In 2006, Indian production was reduced owing to severe flooding in November 2005 that curtailed mining until mid-April 2006. Morocco has been the third largest supplier of crude barite to the USA and world drilling market. In 2003 and 2004 their shipments of crude barite to the USA were not significant. In 2005, Morocco resumed shipment of crude barite to the Gulf Coast and began supplying barite ground to meet API specifications to the Gulf Coast.

Jan 1, 2009

By M. Botz

For leach solutions containing primarily free cyanide, the silver nitrate titration method is a rapid and acceptably accurate means of analyzing for cyanide. However, in leach solutions containing elevated levels of copper, the titrimetric method significantly over-estimates the concentration of free cyanide and under-estimates the concentration of weak and dissociable (WAD) cyanide. The authors have developed a modified potentiometric titration method for determining WAD cyanide that overcomes issues with high copper levels in solution. The new MP-WAD method involves addition of a chemical ligand to the sample prior to silver nitrate titration to fully release cyanide bound to copper. Once released from copper, cyanide in solution is no longer affected by the presence of copper and titration results are quantitative rather than empirical. In multiple laboratory trials with synthetic solutions and complex actual leach solutions, accurate WAD cyanide measurements were achieved using the MP-WAD method. Analyses obtained with the new method were found to be within about ±10% of analyses obtained with the USEPA OIA-1677 WAD cyanide analytical method.

Feb 27, 2013

By Peter Loehr

Full-face tunnelling machines were introduced into German coal mines 12 years ago. It was aimed to utilize these highly efficient systems to drive mine tunnels in rock so that the large demand for development work in some mines could be met. A characteristic feature of coal deposits in Germany - and particularly in the Ruhr Area - is a thick overburden strata. Access is therefore only possible through vertical shafts. A network of horizontal drivages leading from these shafts open the deposits between the different mine levels. The hardcoal-bearing formations are multi-folded and heavily tectonically stressed. Apart from a few extensive fault zones there are many single faults of different natures in the carboniferous strata. During the course of decades coal mining has penetrated to ever increasing depths. Nowadays coal is mined from depths of between 600 m and 1,200 m. The effects of ground pressure in connection with extremely varying rock strengths and high temperatures are particular difficulties which have to be overcome during drivage work. The first full-face tunnelling machines to be applied in the mines had originally bee deigned and developed for tunnelling projects. Not only the machines themselves, but also the back-up equipment had to be adapted to meet the special demands of German coal mines.

Jan 1, 1983

By Thomas Schwind, Pamela S. Moran

For short tunnels, a reinforced cast-in-place lining is not economical and shotcreteis a logical substitution. In the past, reinforced shotcrete linings have been constructed with lattice girders and welded wire fabric. For the Russia Wharf Tunnel in Boston, MA, the Contractor, with the help of the Dr. G. Sauer Corporation offered the MBTA a VECP to substitute the reinforced cast-in-place concrete lining with a steel fiber reinforced shotcrete lining. The challenge was to adequately model the ductility of the steel fiber reinforced shotcrete and to test the shotcrete prior to and during construction to assure quality control. To our knowledge, this type of numerical simulation has not been used on any other tunnels in the US.

Jan 1, 2005

By J. E. Bernick, J. Davies

This paper describes the design and construction of a 22.86 m (75 ft) long jacked tunnel, which was successfully installed, despite difficult mixed face conditions at Metro-North’s Westport Station, in Connecticut in the fall of 2003. The tunnel utilized what is believed to be, the first application of a steel grillage system within the United States. This grillage was installed before the jacking started and allowed the tunnel to be jacked under four live railway tracks, which included the Acela high speed line, without affecting train operations. The clearance between the top of the tunnel and the rails was only 0.9 m (3 ft).

Jan 1, 2005

By K. Park, J. Sohn

Recovery of industrially useful metals from various secondary sources is an important issue in Korea whose natural resources are limited and needs in the strategic metals are on the rise. In order to meet such needs, researchers at the Korea Institute of Geoscience and Mineral Resources have launched a number of projects to help the nation to recover various metals from secondary sources. In this study, silver is successfully recovered from spent silver-oxide batteries first by distillation to remove mercury. The distilled residue was next subjected to leaching of silver using nitric acid. The study involves finding optimum conditions to leach silver from the distilled residue and subsequently to recover silver from the leach liquor by chemical precipitation. The chemically precipitated products are then subjected to reduction roasting to recover silver metal.

Jan 1, 2002

By E. McCullough

"Fostering positive community relations is a principal tenet of sustainable development, but conflict can test even the strongest of relationships. While conflict surrounding resource development projects has the potential to be destructive, it may actually pose opportunities for partnership and collaboration when managed effectively. It is therefore not only important for mineral resource professionals to recognize the financial and social costs associated with legal disputes among project stakeholders, but also for them to prioritize resolving social conflict using alternative channels that allow for win-win outcomes. A variety of dispute prevention and resolution techniques do exist, but successful practice is not yet the norm. Here we review the sources and consequences of social conflict in the context of mining projects, and discuss typical and alternative approaches to conflict management in light of their respective benefits and drawbacks. We also suggest implementation of conflict resolution lessons into resource-related university curricula as a critical step in the continued shift of the mining industry towards sustainable development. INTRODUCTION Social conflict is a recurring phenomenon in the human experience and serves as a critical mechanism for change [1-5]. It occurs when two or more parties perceive that their needs and interests are in direct competition with each other and believe they cannot be reasonably accommodated. Conflict over mineral resource activities, particularly the distribution of benefit and risk, has become an omnipresent issue throughout the world [6-7]. Contrary to common perception, however, conflict can be a positive, transformative encounter in some instances [2, 8-11]. For this to be possible, society and its acting agents must reconsider how to address conflict. What if conflict were only a challenge to try something different? It is well-understood that the mineral industries must manage an increasingly significant volume of social conflict [12-13], which can be a costly externality impacting all of whom are involved. Conflict is commonly considered in a two-party sense, but this can deeply over-simplify the true number of stakeholders. Besides mining companies and community members, government policymakers and regulators, public interest groups, and judicial systems, to name a few, bear the social expenses of poorly-managed conflict [4, 6, 12, 14-22]. It is desirable for interested parties to participate actively in a constructive way to pursue their needs rather than contributing to adversarial relationships, operational problems, and legal costs [1, 4, 12]. Some mining companies are of course already working to develop more productive relationships with their stakeholders, but there is undoubtedly still a gap between ideal and common practices. This gap can inhibit collaboration and threaten the potential for mutually-beneficial resolutions to complex social issues [12]."

Jan 1, 2016

By D. William Tedder

Several bauxite residue sands and muds produced by Bayer plants in the U.S. and overseas have been fractionated using dry and wet magnetic separators. The magnetic sand fractions typically contain about 60 wt% iron and the bulk of the radioactivity in this waste. The muds are more difficult to process than the sands, but some fractionation is possible using a combination of flotation and magnetic separation techniques.

Jan 1, 1984

By Raja V. Ramani

As the new millennium approaches, it is appropriate to assess the progress that has been made in mine health and safety, a matter of concern to management, labor and government. One can hardly look at the major events of the last century — from the birth of the US Bureau of Mines through the enactment of the modern health and safety laws — without realizing that the march has been relentless toward eradication of health and safety threats in mining. The progress is spectacular in mine safety and significant in mine health. In looking at the future, it is safe to assume that societal demands will increase for improved health and safety conditions in the workplace. So will the demands for greater technological leaps. The standards will for measuring success and the expectations of progress in creating a safer and healthier mine environment will grow. The possibilities are enormous of meeting these exacting requirements in the 21st century.

Jan 1, 1999

By C. Chamberlain

The mining industry continues to underpin the regional economy. Australia, benefiting from a weak currency, receives 27% of the total goods export value from non-energy mining lead by aluminium, iron ore, gold and nickel. Consolidation has eliminated CRA, Comalco, North, Savage, Acacia, Ashton, Great Central, Aberfoyle, Placer Pacific, Plutonic, Normandy and RGC leaving Rio Tinto, BHP-Billiton, WMC, MIM and, increasingly, the South African companies Anglo, Gold Fields and Harmony as dominant players. Exploration stagnates with expenditure dropping 40% in Australia and 80% in PNG from peak levels. Major new regional developments include Rio’s West Angles iron ore project, Newcrest’s Ridgeway gold-copper mine and Inco’s Goro nickel-cobalt project in New Caledonia.

Jan 1, 2002

By C. Laughton

The Deep Underground Science and Engineering Laboratory (DUSEL) is to be constructed at the defunct Homestake Mine, in South Dakota. As a cornerstone of DUSEL?s research program, it is intended to conduct experiments into the fundamental nature of neutrino and proton particles. The experimental apparatus required to con-duct these experiments will be housed in large rock cavern(s) sited at depths of over a kilometer. As conceived, these cavern(s) are planned to have mined volumes of up to half a million cubic meters, and spans of approximately 50 meters. The paper will describe key end-user requirements, and outline the in situ rock conditions and mine site constraints that are likely to play determinant roles in identifying candidate sites and developing cost-effective design options(s).

By Jim Nickerson, James McCleish, Tom Abkemeier, Nicholas Willig

The purpose of this project is to convey sanitary sewage from an existing pump station to a new waste water treatment plant. This paper will discuss the design and construction aspects of the project. The scope includes construction of three main shafts ranging from 34 to 100 feet in diameter at depths of 200 to 230 feet and 21,000feet of tunnel. Shaft construction consisted of slurry wall excavations keyed into claystone and limestone at depths ranging from 114 to 130 feet, followed by rock excavation utilizing drill and blast methods. The tunnel is being excavated in the Warsaw and Salem shale and limestone formations utilizing a 12'-6" diameter Wirth hard rock TBM.

Jan 1, 2005

By Stephen F. Munsell

The development of transportation systems for mined materials has historically been characterized by steadily increasing sizes in basic hauling units. This is especially true for open pit mines for which success is dependent upon the economical transportation of vast quantities of material. The depletion of high grade ore reserves has mandated a tremendous increase in the size and complexity of the ore haulage systems necessary for open pit mines, These increased demands were served by rail haulage systems in the early large open pit copper mines while later developed properties opted for the flexibility and lower initial costs of truck haulage. Now, we find the trucks being displaced as large overland belt conveyors tackle the problem of handling these ever larger quantities of low-grade ores with accompanying overburden ratios that can run as high as 10:1 or even 15:1. The basic development of large conveyors with shiftable sections and modular belts has generally taken place overseas, during the last few decades. The coal fields of central Europe proved an ideal testing ground for conveyor innovation because the low density and natural friability of the material created an ideal medium for transporting by belt conveyor. Now these proven ideas are being considered for and implemented into both the soft and hard rock mining industries of the United States.

Jan 1, 1978

By W. Burger

Mechanical excavation methods can significantly improve excavation performance and labor safety compared to drill and blast operations. Herrenknecht has developed a mechanized shaft sinking method for soft and medium strength rock. This system combines innovative technologies which allow simultaneous excavation, removal of cut material and the installation of rock support. This Shaft Boring Roadheader ?SBR? is flexible in diameter and can be used in shafts with changing diameters and different shaft support requirements for depth up to 2,000 m. During regular excavation personnel are not required to access or work on the shaft bench. The boom used to cut the shaft profile is based on roadheader technology.

Jan 1, 2012