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By Ginger L. Hustrulid

Conveyor belts are a critical component in tunneling projects. This paper reviews current design considerations for conveyor belts. Rubber compounding differences to meet local fire resistance regulations or certain cover characteristics such as higher abrasion resistance or low carbon footprint rubbers for applications are reviewed. Evaluation of fabric belts, steel cable belts and the benefits of each carcass design for a particular use is also examined to help with proper carcass selection to decrease downtime from unexpected failures. Finally, this paper takes a look at some of the differences when working in metric versus imperial units.

Dec 1, 2022

By R. E. Gertsch

A mobile-modular carbon adsorption mill design and operation for small to medium sized heap leach precious metal mines is presented. In the mobile-modular strategy, charcoal columns with adsorbed metal move from small strategically located carbon adsorption loading stations to a central stripping facility and back. The design has many advantages: 1) It scales-up from pilot plant to full production. 2) It has low capital requirements. 3) Operational costs are competitive with other systems. 4) Mill production can react quickly to changes in ore grade or property area. 5) The solution circuits are simple and easy to maintain. 6) Charcoal damage is reduced.

Jan 1, 1993

Those who have had an occasion to apply geostatistics to the estimation of ore reserves are familiar with the conventional approaches of estimating average grade of quality values for arrays of regular grid squares or blocks. Further, the technology to perform geostatistical analysis and prediction for irregular two-dimensional areas has been available in a practical, readily useable form for some time. However, the generalization of this technology into three dimensions has been hampered by lack of a suitable geometrical characterization for realistic, three dimensional shapes and volumes. The extension of these estimation techniques into three dimensions has now been made possible by a successful integration of the volume modelling capabilities of 3D Component Modelling with proven 3D Geostatistical Techniques. The result is a powerful new technique for mineral ore reserves estimation in a practical, useable form. The technique allows direct geostatistical estimation of grade and quality values for precisely defined, irregular, realistic, geological, and mining shapes or volumes. This paper describes the two technologies, their integration and their application in practice to the estimation of mineral ore reserves. The paper closes with a discussion of the benefits provided by the new approach, in terms of accuracy, efficiency and practicality.

Jan 1, 1991

By John J. Gillis

There is an ongoing battle to gain general acceptance of fossil fuel byproducts as safe, economical and useful agro-industrial materials. Despite that, the US ash industry is witnessing a steady growth in the volume of coal burned, along with the production of greatly refined, higher-quality ash particulates. There are two principal reasons for this. Economics have caused an increasing number of US electric utilities to convert from oil-burning to coal-burning. And the Federal government has tightened specifications on fly/bottom ash production quality. Hence, it must be noted that new and more stringent Federal regulations were implemented in 1980. The resultant ash particulates are finer, more compact, and less heavy than in previous years. Additionally, the first shift from oil to coal in the US was initiated in December, 1979 by the New England Power Co. in Massachusetts. Coal is the most widely-distributed fuel in the US. And it is found in 38 states. The wide availability of this fossil fuel and its general cost-efficiency, coupled with the undaunted move of US electric utilities toward nuclear power, are major factors affecting the current statistics on ash generation (65.4 x 106 million tons). Interest in the use of coal in power plants is creating a unique ash disposal and use situation for ash producers as well as the Federal government. There are growing quantities of fly/bottom ash residue. Ash producers must decide how this byproduct can be dealt with effectively and profitably. At the same time, government agencies such as the US Environmental Protection Agency (EPA), are commissioned by Congress to assure that solid, liquid, or gaseous material released into the environment is not harmful or offensive to human health and the environment. Additionally, the Federal government is often responsible for establishing and enforcing guidelines and standards governing the use of recycled materials. Several standards and guidelines governing the properties and use of ash in the US have been established by governmental agencies as well as by the ash industry itself. Of these, some have been developed for ash use by a specific federal agency. Others apply to the entire industry. The following is a brief identification of the major specifications for fossil fuel ash: • US Corps of Engineers - These specifications were first established in 1957. They delineate the physical and chemical requirement for pozzolans used in mass concrete. These specifications applied only to Corps of Engineers' concrete construction projects for locks, dams, and other mass concrete projects until 1977. At that time, a joint effort between the American Society for Testing and Materials and the Federal government produced a modified specification that is now generally applied. The Corps of Engineers' ash, however, retained certain aspects of its specifications for its own use, particularly in the area of handling and shipping fly ash to its own projects. Prior to transporting the fly ash to the corps, all potential sources for the ash must be inspected and approved as a supply source. All silos must be filled, sealed, and tested before the ash is released for shipment. The normal test period for the ash is seven days, although several testings may require up to 28 days. Once the fly ash has been released, it can only be shipped to US Corps of Engineers' projects. All shipments are made with a government inspector present during loading. After a truck or railcar is loaded, the silo is resealed until the next shipment. This procedure requires three silos, and a minimum of 454 t (500 st) each should be considered for each storage unit. All silos are strictly committed to Corps of Engineers' use and are not available for other commercial shipments. • US Bureau of Standards - This Federal agency maintains a standard testing sample of nearly every product used in the US. The accuracy of the fly ash chemical analysis is measured by a regular cement and concrete reference laboratory (CCRL) inspection and based on test results from a standard sample of cement. • US Bureau of Reclamation - This agency pioneered several projects using fly ash and required Federal Standard Certification for pozzolans. • American Society for Testing and Materials (ASTM) - This nongovernmental organization began preparing standards for fly ash sold and used in the cement and concrete industry in 1947, at the urging of ash marketing firms. Current standards define chemical and physical requirements and is entitled, "Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete (C 618-80)." • State Highway Specifications - Led by Alabama, many states are moving toward permitting - and in some cases requiring-the use of fly ash in portland cement concrete and with lime for base stabilization projects for roads and highways. • Federal Aviation Administration (FAA) - The FAA acts in an advisory capacity. It has final approval on design specifications for airport construction projects. The agency has established a set of guidelines permitting the use of fly ash, and has approved several fly-ash-specific designs. The most current FAA fly ash projects

Jan 8, 1984

By Jon “Ike” Isaacson, Frank Perrone, Eric Prantil

"Tunneling through an urban environment carries many inherent risks to the immediate local infrastructure and subsequently to the project stakeholders. On the CQ031 Contract of the East Side Access Project in Queens, New York, twin 22.5’ diameter Herrenknecht Slurry TBMs were mined within close proximity to many infrastructure assets, with cover of less than half a shield diameter at times. Multiple public bridges and critical railroad infrastructure including catenary poles and signal towers supporting the busiest rail interlocking in the United States required underpinning systems. The support program for these structures was refined over the course of the four tunnel drives. It is the intent of this paper to show how the interaction between the temporary structures, instrumentation monitoring plan, and risk assessment program melded to provide a system which the owner, contractor, and designer relied on as a tool to ensure the project success without impacting the public surroundings. PROJECT BACKGROUND The East Side Access (ESA) megaproject located in New York City, N.Y is a multi billion dollar program for the Metropolitan Transit Authority Capital Construction (MTACC) with the main goal of bringing the Long Island Railroad (LIRR) commuter rail to Grand Central Station located in the heart of Midtown Manhattan. When completed, the project will significantly reduce congestion both into and out of Penn Station, the current terminus of the LIRR. In order to accomplish this, multiple contracts of varying scope are required to operate simultaneously in both Queens, N.Y and Manhattan. In 2009, the CQ031 Queens Bored Tunnels Contract was awarded to the joint venture of Granite Construction Northeast, Traylor Bros. Inc., and Frontier Kemper (G.T.F). The main scope of this contract was to excavate four segmentally lined soft ground tunnels underneath the Sunnyside Rail Yard in Queens, New York. Additional scope of work included the construction of a tunnel approach structure, electrical substation, and multipurpose ventilation and egress facility."

Jan 1, 2016

Direct force measurements were conducted using an atomic force microscope (AFM) to study the mechanism of copper-activation of sphalerite. The force measurements were conducted between a sphalerite plate and a hydrophobic glass sphere in xanthate solutions of various pHs. The glass sphere may represent the hydrophobic air bubbles interacting with minerals during flotation. The force measurements conducted with unactivated sphalerite in 10') M KEX solutions did not show the presence of hydrophobic force. On the other hand, the results obtained with copper-activated sphalerite at pH 9.2 and 4.6 showed strong hydrophobic forces. However, the results obtained at pH 6.8 showed no evidence of hydrophobic force, which provides an explanation for the difficulty in floating sphalerite at neutral pH.

Jan 1, 1998

By Allan E. Hall

The use of full face boring machines in underground mining has increased considerably in recent years and over 200 raise-boring machines are now in use in the Western World. Several tunnel-boring machines have been tested notably in America, West Germany, Britain and South Africa. A relatively new concept is the blindhole borer, where the machine stands on the lower level and bores a full diameter raise upwards without the use of a pilot hole. Four of these machines have been tested to date in South African quartzites with varying degrees of success. The development of boring technology has created new problems for ventilation engineers and exacerbated several existing ones. This challenge has been met in many varying ways and this paper attempts to provide a review of the current state of the art. Technology and methods are developing at great speed in this field and therefore no final and absolute solutions can be proposed, since each machine and site pose individual problems which are best handled by local knowledge and experience.

Jan 1, 1980

By J. S. Jaspal

Mining of thin coal seams is both difficult and uneconomical. As a result, most of thin-seam coal reserves in the U. S. are not being mined. It is estimated that nearly 910 Gt (K. Unrug, 1985) of coal reserves exist in 355 to 710 mm thick seams. The Bureau is attempting to develop new techniques for mining 150 to 1065 mm thick coal seams. This paper summarizes the research work on existing thin-seam mining techniques, testing on small and full scale physical models of the Bureau slot mining concept, and computer modeling of the full-scale process.

Jan 1, 1992

By R. L. Miller

"Miners worldwide use a tremendous amount of energy in producing finished minerals for the end user market. In accomplishing this goal, they incur energy costs that can range from 20% to 30% of the total cost of production, so there is fertile ground for cost savings. To unlock this huge value in cost reduction, energy analysis is the key and is broken into several segments: 1. Fuel analysis for power generation 2. Energy supply & demand 3. Opportunity cost for lack of power 4. Backup power 5. Power contracts 6. Energy efficiency 7. Renewable energy 8. Continuous energy management FUEL ANALYSIS FOR POWER GENERATION What is the first thing we evaluate when looking at power supply alternatives for the mining industry’s large power requirements? Is it 1) site, 2) engineering, procurement, and construction companies, 3) independent power producers, 4) turbine vendors, 5) grid connections, or 6) fuel supply, logistics, and infrastructure? In evaluations of power supply alternatives for mining companies with special emphasis in developing countries, there is one over-riding conclusion: reliable fuel supply drives the energy generation economic engine. Evaluating several different fuels including liquefied natural gas (LNG), natural gas, diesel, heavy fuel oil, and liquefied petroleum gases (LPG) among others, the best project outcomes are those where fuel supply, pricing, logistics, and infrastructure are given an extensive amount of time during the analysis stage. In an assessment of the twenty-year costs of generating power from multiple fuels, each fuel’s costs were placed into three separate net present value (NPV) buckets of: 1) capital, 2) operating and maintenance, and 3) fuel. Within a range of 65% to 85% for all fuels, fuel cost was the largest component of the NPV of the life cycle power generation costs. So if 65% to 85% of your life cycle power generation cost is one item, shouldn’t miners spend a corresponding amount of time in the analysis stage fully understanding this key determinant for a successful power project? In developing countries where power generation infrastructure may not exist or does not exist at the same level as is found in North America and Europe, fuel analysis becomes even more important. One of the key questions for fuel importation in developing countries is the draft at existing ports to allow larger vessels to dock at the jetty. Can larger ocean-going tankers dock at the port for off-loading, or is the port’s draft too shallow, thus forcing a Single Point Mooring (SPM) system or Conventional Buoy Mooring (CBM) system to be constructed at substantial capital expense? Once fuel can be imported, sufficient onshore storage capacity should exist, or must be built to off-load the entire fuel cargo from the larger ships. Additionally, the throughput capacity of the pipeline from SPM/CBM must allow a rapid unloading of the fuel from ship to shore to eliminate steep demurrage costs for the project."

Jan 1, 2017

By Ehsan Alavi Gharahbagh

Tool and cutterhead wear is a crucial issue in soft ground tunneling, especially because tool inspection, maintenance, and replacement are done under difficult conditions, and often under pressurized faces or under ?hyperbaric interventions?. Overall, tool inspection and changing is a time consuming and costly step, which needs to be quantified and the related costs accounted for in any construction contract for scheduling and costing of the tunnels at design stage or bid preparation. However, lack of a universally accepted index or measure for soil abrasivity in the geotechnical reports has made it difficult, if not impossible, to define cutter wear for this purpose. Soil abrasion and its impact on cutting tools for tunneling machines under dry or wet conditions have recently been under spot light due to construction claims in several of the recent tunneling projects. The objective of this paper is to examine soil?s physical, mechanical and tribological properties related to the interface of the soil and excavation tools and discuss ways to measure soil abrasivity in a quantitative and repeatable manner. The paper will discuss the efforts that are underway to develop a new soil abrasivity index and the fabrication of a new testing device for this purpose.

Jan 1, 2010

By Jay Parrish

Appalachian kimberlites appear to be spatially distributed along two structure parallel trends running from Tennessee to New York. It is hypothesized that the kimberlites were emplaced at the intersection of structure parallel basement faults and cross- structural lineaments. The latter are expressed in potential field and remotely sensed data. The western trend follows the Rome Trough from eastern Kentucky to south central New York. The eastern trend parallels the edge of the Ridge and Valley in Virginia and Maryland.

Jan 1, 1984

By Ching-Yi Tsai

The effect of various constituents on the pyrolysis and combustion of a pulverized coal in an entrained-flow reactor has been inves¬tigated. Predicted time-temperature histories of the coal' particles and experimental weight loss data indicate a strong coupling of heat and mass transfer to the pyrolysis and combustion rates. A higher combustion rate following ignition was observed as particle size was increased to 112 µm. This is related to a higher particle temperature after ignition for the larger particles. Although the heating rate prior to ignition decreases with increasing particle size, higher slip velocities and surrounding gas temperatures for the larger particles promote early ignition. The presence of liptinite in the coal increases the weight loss rate before and immediately after ignition. Similar behavior was observed for pyrolysis. Fractions of a HVA bituminous coal which were rich in mineral matter or semi-fusinite were found to have a higher heterogeneous char combustion rate than vitrinite rich samples.

Jan 1, 1984

By Dennis R. Twining

Recently a mining analyst for a major bank called me to say that during his travels he had encountered an electric utility interested in a new uranium supply. Since we produce uranium as a by-product of phosphate operations rather than as a primary product, he assumed we simply sold our output in the spot market and that a new prospective purchaser would be of interest to us. This assumption was incorrect; the uranium had already been sold on a long term basis at terms more favorable than the currently depressed spot market. From the outset our approach to the marketing of uranium was based on the principle that by-product marketing is not unlike primary product marketing. This was particularly appropriate in the case of uranium, as we were planning a considerable technical and capital commitment to a new business. This illustrates: that the fundamental principle in by-product marketing is to follow a primary product strategy; that the terms "by-product" or "co-product" are creations of accountants; that they have no place in marketing decisions! Traditionally, the term "by-product" has implied that only a secondary marketing effort is required. Recent history has contradicted that view by demonstrating that by-product values can have marked impact on a mine's revenues and costs. In fact, by-product values can spell the difference between success and failure.

Jan 1, 1983

By P. Maraboutis

Extractive industry (mining and quarrying operations), as other industrial activities, is subject to environment protection laws, regulation and standards such as the Environmental Impact Assessment directive, Natura 2000, Habitats & Birds directive, Water Framework directive etc The European Commission (EC) is aim to strengthen the EU environmental legislation to improve the (environmental and human) safety of mining activities. The mineral processing and the management of the mining waste will be covered by the new amendment of the Seveso II Directive, by a Best Available Techniques reference document (BREF) describing the Best Available Techniques of mining waste management and a new directive on the mining waste management. At the same time initiatives as the environmental liability, the energy taxation for environmental reasons and the natural resources management policy, which will have a positive impact on the protection of the environment, will affect the extractive industry operation procedures.

Jan 1, 2002

By Lawrence Tsang, Conrad Ng, Tim Leung, Peter Poon

"The Mined Tunnel is part of the Central-Wan Chai Bypass and Island Eastern Corridor Link (CWB), which is a strategic road along the northshore of Hong Kong Island targeted to alleviate the heavy traffic congestion. The objective of this paper is to review the performance of construction of a 160m long Mined Tunnel with a trinocular cross-section area of 460m3 and a combined span of about 50m underneath the southern approach ramp of the existing Cross Harbour Tunnel (CHT) by sequential excavation method (SEM) in hard rock. Mechanical excavation of tunnel by adopting the New Austrian Tunnelling Method (NATM), together with the application of NGI Q-system allows observational approach and optimization of temporary rock support design. Furthermore, the good performance of optimized rock support and the stability of CHT are confirmed through instrumentation monitoring review. This paper also discusses the selection of different tunnel plant and equipment to achieve the planned rates of tunnelling by mechanical excavation in competent granitic rock. INTRODUCTION The works of the CWB mainly comprise construction of 4.5km dual three-lane trunk road, of which a 3.7km section is a tunnel connecting Rumsey Street Flyover in Central to Island Eastern Corridor at North Point (see Figure 1). The Mined Tunnel runs from the ex-Public Cargo Working Area (ex-PCWA), underneath the existing CHT, and through the Causeway Bay Typhoon Shelter. The Mined Tunnel passes at an oblique angle beneath the southern portal of CHT over a length of some 50m. CHT is the primary sensitive receiver of this project and is utilized with a daily throughput of about 120,000 vehicles that far exceeds the design capacity of 78,000 vehicles per day. Hence it is necessary to choose the most appropriate tunnelling method to preserve the structural integrity of the CHT. Other sensitive receivers in the vicinity include structures to the north of the Mined Tunnel, the Royal Hong Kong Yacht Club (RHKYC); and to the south of the Mined Tunnel, the Police Officers’ Club (POC)."

Jan 1, 2016

It took me nearly nine months to make the move from Arizona to Berkeley, opening an office and planning our new home. While I was in Warren Dorothy had rented two rooms for my office In the new California Commercial Union Building at 315 Montgomery Street in San Francisco. She made such a good choice that this remained my address for more than 50 years Dorothy had also looked over many lots In Berkeley, and took an option on the one that pleased her the most. It was a beautiful lot, or rather three, as we took three lots to protect our view. The only possible drawback was that it was in a new district and there were only two houses within two blocks. No one could tell how the area would develop but we liked it so much that we bought the lots on the spot and signed a note to guarantee payment. Dorothy's good judgment was shown by the fact that after 50 years we are still glad to be living on the same property, at 168 Southampton Avenue. We arranged a meeting with the distinguished architect Bernard Maybeck-and employed him to design a house for us. Dorothy spent most of her time with Maybeck planning the house and an attached studio for her, and she later wrote an amusing essay on her dealings with Maybeck. They were so successful that even now we could not think of any changes we would have wanted. It took several months to design a house that suited Dorothy and would fit on our hilltop. I was glad to overcome some of Maybeck's scorn for "only an engineer" by showing how, by rotating the studio addition 45º, it would fit the lot without serious excavation. We finally signed a contract with Maybeck, borrowing so much money that it scared us. First Consulting After short jumps to the gold mines in the Secret Pass District near Kingman, Ariz., and to the Espiritu Santo prospect adjoining the rich

Jan 1, 1976

By -Ing. Alexander Dohmen, -Ing. Gunter Hagen

In order to improve the thermal environment in deep coal mines, two principles can be applied: firstly, the reduction of heat flow into the air stream, and secondly, cooling of the air current. First of all one should try to minimize the heat-flow rate into the air stream underground by the mining method itself. German coal mines prefer the caving system of advance longwall mining simultaneously on several levels with ascensional ventilation. The effects of descensional ventilation and different face ventilation layouts on the thermal environment are discussed, besides the effects of pneumatic and hydraulic stowing. Application of all mentioned possibilities together instead of today's common mining method would reduce the Basis Effective Temperature considerably. In the future, hydraulic haulage of the raw coal underground substituting belt conveying may be a mean to improve the thermal environment further on. If the working depth of a coal mine exceeds about 1 000 m, cooling of the air stream under-ground will be necessary in addition to the above- mentioned measures. Generally, in German coal mines different types of indirect-contact air coolers located nearby the face are used. Besides such so-called cooling coils, large-capacity spray coolers are used because they work more efficiently if a great cooling duty is demanded. Common designs of both air cooler types and their possible utilizations are demonstrated. Deep coal mines in the Federal Republic of Germany need up to 30 MW of total cooling capacity. Mostly, the needed chilled water is cooled by large-capacity refrigeration plants placed on surface, underground or in combination of the above locations nearby the shaft. Due to the increasing underground cooling demand, the distribution of the chilled water and the control of the air coolers become more important. The conception of a control system is discussed, which is based on the control of the single air coolers. All air coolers of a mine are controlled so as to optimize the supply water-flow rate with regard to the demanded cooling duty of the coolers. On the next upper level of the control system the whole chilled water network and finally the refrigeration plant is regulated. Present research work deals with the use of ice for cooling mines. There are some unsolved problems in this new cooling concept. Some aspects of making, transporting and storing ice are described. The use of ice may probably reduce the cooling costs of German collieries, which are at present approximately 4 DM per ton of saleable coal.

Jan 1, 1989

By N. M. Grant, W. G. Prast

Jamaica has extensive deposits of marble, gypsum, and limestone, offering prospects for commercial sales to nearby US markets, notably the Gulf Coast and Southeast. Stare-owned and private Jamaican industrial minerals producers have made limited sales to date but expect to increase exports during the balance of the 1980s. Restraints include Jamaican government controls on access to essential foreign exchange for new capital investments and distribution of profits. Jamaican efforts to identify market opportunities in the US are reviewed, and the outlook for further exports of carbonates is discussed.

Jan 1, 1987

By G. R. Goldak

All of Canada's older uranium mining areas have been intensively prospected and known outcrops have been repeatedly examined. The only ground in these areas which has not been explored is that which is covered by water or other overburden. The discovery of new mines in these areas will, in the author's opinion, depend on the development of new geophysical or geochemical tools capable of locating uranium deposits which are-buried beneath tens to hundred of feet of overburden. Such tools would be extremely useful in Saskatchewan's Cluff Lake and Wollaston Lake areas. Uranium has recently been discovered in significant quantities in these regions but exploration is made extremely difficult and expensive by an almost uniform overburden cover. The author's experience has been confined to Canada but apparently a subsurface uranium prospecting method could be widely exployed in the western United States and Australia as well. Radon-222 measurements have been used for more than a decade on practically a worldwide basis in an attempt to obtain a useful method for subsurface uranium prospecting. It is well known that ha-222 produced by buried uranium deposits can diffuse through an overburden cover so that it can sometimes be detected at surface. An advantage of this method of prospecting is that Rn-222 can be detected with a simple scintillation, ionization or semiconductor detector. One of the essential weaknesses of the method is that the mean diffusion path length of Rn-222 is limited by its very short (3.8 days) half life. For a deeply buried deposit, vitually all of the Rn-222 atoms will decay before reaching surface and, therefore, such deposits cannot be expected to produce a detectable radon anomaly. Thus, except in unusual cases where groundwater or ground air flow assists the movement of radon towards surface, the depth of exploration is probably limited to ten or twenty feet of overburden cover. The high solubility of Rn-222 in water is also a source of difficulty. In an area where overburden covers bedrock with water saturation of the lower overburden levels, the radon will simply dissolve in the groundwater, and soil gas readings at surface will indicate falsely low

Jan 1, 1974

By Ahmed A. El-Saie

To reduce the problem of overbreak and its associated added costs, a new technique is proposed to make a slot around the tunnel profile in hard rock. The Finite Element Method was used to investigate the effect of the slot on the stress field and deflection of the tunnel core. Beam theory was also applied to calculate the stresses and deflections of a slotted tunnel for several different slot depths.

Jan 1, 1981