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By Werner Burger

After its first introduction in 2013, Variable Density TBMs have increased their application significantly in mechanized closed mode tunneling. Throughout a variety of successfully completed and ongoing projects since then, Variable Density TBM technology has demonstrated its advantages in a wide range of applications. This paper will present the developments and lessons learned from these projects as well as the future potential of Variable Density TBMs.

Jun 13, 2021

By P. Chauvet

From a computational point of view calculating a variogram is a perfectly simple operation. For any particular study, we know which variable is to be studied. We also have a good idea of structural parameters which are likely to be important (the scale of the phenomenon, the probable direction of the anisotropy, etc.). Finally, we know the structure of the data file. So we can specify the parameters to be used to calculate the variogram (the distance classes, the angular classes, etc.). This allows us to decide which variogram program is most appropriate (1, 2 or 3 dimensional data, regularly or irregularly spaced, etc. ) . In general, the basic statistics (mean, variance, correlation? etc.) have been calculated beforehand, and so the distribution of the data is already known. Consequently, the choice of the parameter values fed into the variogram is by no means arbitrary. But it must nevertheless be made before the' variogram is calculated. If the resulting variogram is not satisfactory, the whole sequence of operations has to be repeated. Before going on to see how this can be avoided, it is worthwhile having a brief look at the common causes of "unsatisfactory" variograms.

Jan 1, 1982

The first form of a surety bond was an honest handshake between two or more parties, agreeing to a decision and their personal guarantee of following through to completion. This has all changed. In 1895, the United States Treasury Department disclosed that $35 million worth of personal surety guarantees on file had become worthless. At that time, a law was passed, requiring all surety bonds, in favor of the United States, must be corporate surety bonds. Today, a surety bond is one of the nation's leading financial instruments used to guarantee the completion of an obligation.

Jan 1, 1989

By Merrill P. Allen

The Vernal phosphate rock concentrator is located in the Uinta Mountains near Vernal, Utah. Ore is sedimentary rock from the Phosphoria Formation. Truck and shovel mining is done at a rate of 11,500 TPD. Run of mine ore is crushed and then milled through a SAG mill and ball mill to minus 16 mesh. Milled ore is deslimed using cyclones and hydrosizers. Sands are conditioned with fatty acid, petroleum sulfonate, diesel fuel and frother prior to primary rougher and cleaner flotation. Primary flotation tailing is milled to 95% minus 48 mesh, deslimed in cyclones, conditioned using reagents previously described, and then processed through rougher and cleaner scavenger flotation. Product of scavenger cleaner concentrate is upgraded by reverse flotation of dolomite. Flotation concentrates are combined and dewatered, pulp being milled to 99.5% minus 65 mesh and then thickened to 65% solids. Product is pumped from storage through a 10 inch, 94 mile pipeline to a conversion plant at Rock Springs, Wyoming. Mill tailing is stored behind an earthen dam, water from the settled tailing being reclaimed for mill use.

Jan 1, 1993

By George G. Reed

Approximately 200 samples of iron ores and other iron- bearing materials have been tested for amenability to treatment by the R-N process in bench scale laboratory work. Twelve large lots, ranging in size from 900 net tons to 18,500 net tons, but generally 3,000 to 4,000 tons each, have been processed in the R-N demonstration plant. The ores tested in the demonstration plant ranged from 27 to 70 percent iron content and gave excellent results. (1) The demonstration plant has a nominal daily capacity of 50 tons of high quality iron briquettes and has now operated for over five years. A continuing program of process improvement is carried on between demonstration on potential licenses ores. An important development is the complete elimination of any secondary products which, in the past (2,3,4,5), resulted from treatment of certain low-grade ores.

Jan 1, 1960

By M. Peters, P. Schmäh

The development of renewable energies and a sustainable power grid are the challenges for future energy supply. Underground cables will replace the vulnerable overhead lines, because of their safety benefits. Due to the public environmental awareness, smart tunnelling and trenchless solutions are required for inner-city and cross-country installations of underground cables, as well as for crossings and the landfall sections to connect offshore wind farms to the transmission grid. Methods from the tunnelling and pipeline industry provide a high flexibility in the planning of alignments, including versatile tunnel concepts and the installation of protective pipes with E-Power Pipe and Direct Pipe.

Jun 13, 2023

By William H. Dresher

World trade has increased significantly during the last quarter century. However, a new rational for protectionism is emerging which argues for the restriction of trade as a means of preserving and protecting the environment. Fearing lower environmental standards in the Third World, environmentalists are calling for new trade barriers between the developed countries and the developing countries to combat what they see as "eco-dumping." The "greening" of protectionism and the merging of environmental standards into international trade agreements could fundamentally change the world trading system as well as seriously impact the availability of raw materials to provide for the needs of the peoples in both the developing and the developed worlds. This discussion will deal with the agreements and regulations that promise to influence the trans boundary shipment and recycling of scrap metals and wastes containing metals and their projected impact on world trade and metal prices. Emphasis will be placed on the Base1 Convention, whose restrictions concerning trans boundary shipment of scrap metal and metal-containing wastes for recycling took effect on December 31, 1997.

Jan 1, 1998

By Robert H. Hooff

The Vor-Siv Dewatering and Classifying Unit was developed by the Polish Coal Industry because of a need for a unit that would dewater and classify high volumes of solids in water slurry. To be practical, the unit needed to be relatively small in size, simple in design, involve low operating costs, and be able to give a dewatered product of less than 30% moisture. The answer to the above mentioned criteria was the Vortex Dewatering Sieve or, as we refer to it, the Vor-Siv. The original installation of the unit, as we know it today, began in 1963 when the Pols installed the unit in a full scale pilot application. By 1966, at least 30 of these units were installed throughout the Polish Coal Industry. This equipment was originally introduced in the United States in 1966 at the Fifth International Coal Preparation Meeting in Pittsburgh, Pennsylvania. The first installation in the United States was not achieved until 1970, when Mr. Fred Sachs of The Valley Camp Coal Company, Triadelphia, West Virginia, installed a Vor-Siv in a retrofit application. To date, there are 36 Vor-Sivs installed in this country and 29 in the process of being installed or delivered.

Jan 1, 1976

By Howard C. Homeyer

Coal and water are the two basic external feedstocks required for a coal gasification project. The WESCO project in northwest New Mexico, a joint undertaking of Texas Eastern Transmission Corporation and Pacific Lighting Corporation, will require about 25,000 tons of coal and approximately 7.5 million gallons of water each day to produce 250 million cubic feet per day (MMCFD) of pipeline quality substitute natural gas (SNG). The coal and water supply arrangement with Utah International, Inc. assures the project of an adequate supply of these two vital feedstocks.

Jan 1, 1974

By Richard Switalski, Thomas Scotese, James Morrison, Randall Essex

OVERVIEW Like many older metropolitan areas across the U.S., the Greater Cleveland area is served by a combination of separate sanitary sewers and combined sanitary-stormwater sewers. In 1966, a Master Plan was implemented by the Northeast Ohio Regional Sewer District (District) to minimize pollutant overflows into adjoining Lake Erie and its tributary rivers and streams, that would occur during wet weather events. One component of the Master Plan was to reduce the load on combined sewers by constructing new conveyances to intercept separate sanitary flows and convey them to upgraded regional waste water treatment plants for priority treatment. As part of a 15-year program to construct 74 km (46 miles) of new interceptors, the West Leg Interceptor (WLI) Project intercepts flows from four decommissioned waste water treatment plants (WWTPs), and conveys those flows to the new Southwest Interceptor (SWI), which conveys the flows to the Southerly Treatment Plant, a tertiary level treatment facility. The WLI Project was built in sections to permit decommissioning of the WWTPs as each segment of the interceptor system was completed and put into service. Flows from the first of the four WWTPs was converted to the WLI in November, 1992; the final connection was achieved in July 1994. The WLI comprises 9.1 km (5.7 miles) of 21 to 29 m (70 to 95 ft) deep mainline interceptor tunnel, four vortex drop structures, approximately 2 km (1.3 miles) of shallow tunneled connector sewer to the mainline, approximately 2.9 km (1.8 miles) of open cut connector sewers, five construction work shafts (not including one work shaft constructed under SWI Contract 6 at the north end of the WLI), and 15 access shafts.

Jan 1, 1995

By Saverio Agresti, Giuseppe Lunardi, Donato Basta, Roberto Trapasso

"At a distance of 10 years from the first application of the Nazzano Method, the widening under traffic of a tube of an existing motorway tunnel was realized near Ancona, along the A14 Motorway in Italy. This paper describes the works for the enlargement with conventional method of the second tube, very close to that already widened under traffic.This enlargement was realized very fast, taking into account the advantages of some interesting technological improvements of the Final Design proved in the first tube.INTRODUCTION TO THE WIDENING OF EXISTING MOTORWAY TUNNELSThe widening of a twin-bore motorway tunnel usually considers the double option of creating a third bore as an alternative or closure to traffic of one of the two bores with the resulting reduction in the level of service for users.On the contrary, the extension in situ of a road, motorway, railway or underground tunnel in the presence of traffic, made possible by an inspired idea of Prof. Pietro Lunardi, enables the level of service of the infrastructure to be maintained without the need to resort to alternative routes to create new permanent or temporary bores, not always feasible because of the lack of the necessary space.This construction technique, known as the ‘Nazzano Method’, is part of the technologies refined and offered by the ADECO-RS approach to tunnel design and construction (Lunardi P., 2008) which is increasingly used in the world, leading to the industrialisation of tunnelling (meaning respect for the times and costs set out during detailed design) both in conventional and mechanised (through TBM) excavations.The first true experimentation of the ‘Nazzano Method’ was carried out between 2004 and 2007 to enlarge the two-bore ‘Nazzano’ tunnel (Italy, Milan-Rome A1 motorway) in the presence of traffic, widening it to house from two to four lanes in each direction (Lunardi P. et al., 2007). Following the success achieved in this first application, the Nazzano Method was strengthened considering all the possible suggestions arising from the previous experience and then taken up to enlarge the north bore of the ‘Montedomini’ two-bore tunnel (Italy, Bologna-Taranto A14 motorway), in situ and the presence of traffic."

Jan 1, 2016

By Michael P. Connor, O&apos

The Wing Hill Garnet Deposit, located near Rangeley, Maine, forsed through assimilation of Early Paleozoic metasediments by an intrusive Devonian gabbro. The resulting ore body is exceptionally large and high-grade, consisting of 50-70% almandine garnet. Following open-pit quarrying, the ore is trucked to Industrial Garnet Extractives' mill in West Paris for final processing. Two grades of abrasive are produced - a pure, premium grade INDUSTRIAL GARNET and the Lower grade co-product IGE UTILITY GRIT, both of which are available in a variety of sizes. INDUSTRIAL GARNET is marketed world- wide into a diverse marketplace including both loose grain and bonded applications.

Jan 1, 1985

By K. H. McDaniel, D. M. Loring

The underground ventilation system at the Waste Isolation Pilot Plant provides unparalleled ability to ensure safety of the workers, public and environment. Although small spatially, it can vary the airflow from 66,000 acfm to 460,000 acfm. It can automatically incorporate HEPA filtration in the event of radioactive contamination. Remote-capable regulators individually control the four main splits, and can be adjusted from the surface if necessary. A ventilation remote monitoring and control system provides real-time information. Future areas of concern include DPM compliance, system psychrometry, logic-based-real-time mine ventilation simulation and automation using PLC technology. This paper discusses the evolution of this system.

Jan 1, 2002

By Thomas D. Kaufmann

Introduction What drives the price of gold? Supply and demand, of course. But in ways far different from the forces that drive the prices of other major metals, such as steel, aluminum, and copper. Gold, in fact, is one of the few commodities where both buyers and sellers are happy when the price goes up. Current production, production costs, and variations in production have little influence on its price. Gold inventories are so tremendous that current production has small impact on the amounts available to the market at any time. Worldwide gold inventory and production The world's inventories seem to be between 78 and 98 kt (2.5 and 3 billion oz). Since biblical times, the gold miners of the world have produced about 98 kt (3 billion oz), mostly in this century. Only small amounts have been thrown away and most of it - more than 78 kt (2.5 billion oz) - remain in bullion, coins, or jewelry. About 40% is held by central banks and other governmental authorities, 30% by private individuals as bullion or coins, and about 30% as jewelry. Except for some of the jewelry and the few industrial applications, this inventory is constantly available in marketable form at a price. By comparison, gold production is indeed small. The US Bureau of Mines estimates that the world produced 1.5 kt (50 million oz) of gold in 1986. Consequently, production increased world inventories by only 2%. Variations in production have a negligible or very short-term effect on the supply and, consequently, on the markets for gold. Although South Africa mines about 40% to 50% of the world's annual production, continuing labor strife there does not seem to have ruffled gold prices. Determining gold's price Gold prices, however, do determine cutoff grades in the mines and, thus, do influence production. Nonetheless, changes in production have little impact on the inventory supply. Consequently, it has small influence on the price of gold on the market. With a fairly stable supply, price changes are driven by changes in its demand. Unlike other metals, very little of the demand for gold comes from industry. Dental, electronic, and other industrial uses for gold consume less than 46.6 t/a (1.5 million oz per year). It would be safe to assume that such uses are less than 124 t/a (4 million oz per year) for the entire world. Variations in the 124 t (4 million oz), compared to a supply of 78 kt (2.5 billion oz) of supply can have only a negligible effect. Production net of industrial uses adds perhaps 1% annually to world inventories. This could, in time, affect markets. The increase, however, is mostly absorbed by population growth - more people wanting to own gold - and by gold being put in more attractive forms, such as coins. As an ancient Lydian king discovered, minting bullion permits

Jan 9, 1987

By T. A. Oberhellmann

The Wobbler Feeder is a comparatively new materials handling and separating device. It is essentially a materials separating or scalping machine, particularly adaptable to separation of oversize particles from mine-run ore and to the separation of oversize materials from overburden, where the removal of oversize materials is necessary, as is the case in conveyor stripping. In construction, the Wobbler Feeder is simply a set of transverse bars of manganese steel, or other wear-resisting alloy steel, each having an elliptical cross-section with the major axes of adjacent bars displaced by ninety degrees so when rotating in unison, the pre-determined space between the bars remains constant.

Jan 1, 1959

By Cameron Dunn, Callum Fryer, Carmen Hu, Craig Sewell, Peter Stakne, Andrew Raine

The Woodsmith Project is located in north-eastern England within the North York Moors National Park. The strata contains the world’s largest known high-grade Polyhalite resource of around 2.66 billion tonnes. The Project was initiated by York Potash Limited (YPL), a subsidiary of Sirius Minerals plc., but in March 2020, a takeover was completed by Anglo American, one of the largest mining companies in the world. Polyhalite is an evaporite mineral and contains essential nutrients required for plant growth. The Polyhalite will be extracted via two deep mine shafts and transported underground from the mine site to a Materials Handling Facility on a Mineral Transport System (MTS), which comprises a high-capacity conveyor belt system located within a 4.9 m ID tunnel. In 2018, STRABAG were awarded with the design and construction of the MTS tunnel and associated infrastructure, including the high-capacity conveyor system. The scope of work consists of 300 m of open cut, 100 m SCL tunnel, 36.5 km TBM drive (originally anticipated as three separate TBM drives) along with a network of underground caverns at the Woodsmith Mine. The construction of two 380 m deep intermediate access shafts was later awarded as Amendments to the Contract. The tunnel is constructed using a Herrenknecht Single Shield TBM. As a result of how the various elements of the project have developed over time, the first TBM drive has been extended to ~29 km making it the worlds longest single heading TBM Tunnel when complete. The option of completing the entire tunnel length with a single heading TBM drive is currently being assessed by Anglo American and STRABAG. This unprecedented tunnel length requires two intermediate shafts to provide essential access and services, the first intermediate shaft is at Lockwood beck (LWB) and the second is at Ladycross (LDX). The LWB shaft has been constructed utilising the innovative Blind Boring technique never used before in the UK. This paper will explain the methodology and technical risk management associated with this technique. The authors believe that the collaborative approach between all contract partners is and continues to be the important contributor for the success of this project.

Jun 13, 2023

By G. T. Lineberry, W. J. Wiehagen, L. L. Rethi

This paper discusses a practical method for enhancing the performance of mining work crews. The method, described as the Work Crew Performance Model (WCPM), seeks to define performance variability within similar tasks of an underground work crew. Key components of the WCPM include: •job definition through task analyses, •the ranking of job elements by perceived cost consequence, •observational techniques to establish performance baselines, and •cost linkages between adherence to task procedures and measures of consequence for noncompliance. The components of this model emphasize a reliance on learning from a veteran work force and using that information to reinvest in strategies to enhance safety and efficiency. These strategies are not limited to technological efforts but include consideration of the so-called "soft-skill technologies, " aimed at reducing variability in individual performance and at effecting a continuous improvement in overall system effectiveness.

Jan 1, 1996

By George Innes

The soda ash business in the United States has undergone a sweeping technological change in ihe last 20 years. In a world where synthetics are continuzlly replacing natural products, here we have exactly the opposite, a syntheric chemical being replaced by a natural product. This change is nearly complete in the U.S. and is beginning to take place in Europe and other parts of the world.

Jan 1, 1980

By Walter Meintrup

On Nov. 4, 1981 the newly installed 1000tph wet-process iron-ore ball mill of A/S Sydvaranger completed its first four months of uninterrupted, successful full-load operation in Kirkenes/Norway. This 6.5m diameter mill is driven by a gearless ring or wrap-around motor of 8100kW at 13.1RPM - a first of a kind in this segment of industry. (Fig. 1) This paper analyses the reasons that have led to the selection of this type of drive over more conventional schemes, lists specific advantages of such large mills, and describes in some detail the installation in Norway. General aspects of possible design variations, and application information for designers and users of such mills conclude the presentation.

Jan 1, 1982

By James A. Nunn

Location Xiaolangdi is located in the Henan province of the People’s Republic of China. The distance between Xiaolangdi and the capital of Henan, Zhengzhou, is about200 km. Xiaolangdi is located on the Yellow River at the end of its big characteristic knee. It can be easily found on the map by locating Luoyang. The closest big city to Xiaolangdi is Luoyang (about 45 km). This city has about1 million inhabitants and is well known also to foreigners for its famous historical past. It has been the capital of China through 10 dynasties in former times. Overview The Xiaolangdi Multipurpose Dam Project is located at the last gorge of the middle reach of the Yellow River. The main purposes of the project are: -flood control, - ice jam control, - sediment control, - irrigation, - water supply, - hydroelectric power generation. The project consists of many structures, these are 10 intake towers, 9 flood &sediment tunnels, 6 power tunnels, 1 underground powerhouse, and 1 zone dearth and rockfill dam with a sloping impervious core, 154m high, with a crest length of 1317m. The powerhouse mainly features 6 turbine and generator units of 300 MW, totalling installed capacity of 1800 MW and annual energy output of5.1 GWH. The total storage capacity of the reservoir is 12.65 billion m³ of which 5.1billion m³ is live storage. Of the Yellow River drainage basin, 694,000 km2 or 92,3percent is located upstream of Xiaolangdi Dam Site. Xiaolangdi is located in a key position for flood and sediment control of the Yellow River. Upon completion, Xiaolangdi Dam and Reservoir will effectively mitigate catastrophic floods, the control level will be increased from the present less than 100-year return period up to 10,000 years. Also, it will reduce severe flooding of the river bed of the lower

Jan 1, 1999