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By B. C. Lewis

Have technological advancements in underground coal mining driven people's skills to new highs or have the expanded skills of mining people driven the industry's technological advancements. Who knows? What we do know is that both our technology and our people have made meaningful and significant advancements. Overall, longwall systems continue to increase productivity and retreat faster. Globally, gate road development is the primary bottleneck in a longwall mine. The primary bottleneck in gate road development is roofbolting. Generally, roofbolting is the bottleneck in room and pillar operations as well. This paper will present an integrated manufacturer's (Joy Mining Machinery) vision of the future in comparison to current equipment performance. Particular emphasis will be placed on roofbolter technologies.

Jan 1, 1999

By M. V. T. Da Silva, J. C. Harrison

Eldorado Gold Corporation of Vancouver, B.C. owns and operates three gold mines. The São Bento underground gold mine in Minas Gerais State, Brazil produced 105,907 ounces in1997. The La Colorada and La Trinidad open pit, heap leach mines in Mexico produced over 83,000ounces in 1997. With a deteriorating gold market plaguing the industry throughout 1997 Eldorado had to take critical measures at each mine to enhance gold production while lowering cash operating costs. Each mine had its own unique problems to confront. This case study will discuss three distinct courses of action taken at the three mine sites.

Jan 1, 1999

By M. S. Ellis, D. J. Nichols

In 1999, 1,100 million short tons of coal were produced in the United States, 38 percent from the Northern Rocky Mountains and Great Plains region. This coal has low ash content, and has sulfur content in compliance with Clean Air Act standards (U.S. Statutes at Large, 1990). The National Coal Resource Assessment for this region includes geologic, stratigraphic, palynologic, and geochemical studies and resource calculations for 18 major coal zones in the Powder River, Williston, Green River, Hanna, and Carbon Basins. Calculated resources are 660,000 million short tons. Results of the study are available in U.S. Geological Survey Professional Paper 1625-A (Fort Union Coal Assessment Team, 1999) and Open-File Report 99-376 (Flores and others, 1999) in CD-ROM format.

Jan 1, 2001

By Edward M. Dowey

The concrete lining for a long 8.05 km (5 mi) section of New York City Water Tunnel No. 3 was cast in place. The contractor, Grow-Perini-Skanska, placed over76,841 m3 (100,505 cy) of concrete, pouring 24 hours per day, 5 days per week. The concrete was dropped 204 m (670 ft) to the tunnel level, transported by rail to a concrete remixer and pump, and placed in 146.3m (480 ft) of full circle forms. Some of the many challenges include the sheer magnitude of the job, navigating through drifts, a raise and curves, dealing with ground water inflows, and placing the concrete within time limits.

Jan 1, 2001

St. Peter sandstone is very different from the minerals and rocks that have been studied extensively in mining. On the one hand, it is brittle as characterized by an unusually high friction angle and steeply curved failure envelopes. On the other hand, it is friable, possessing extremely low, and in most cases zero cohesion. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for the mine operators. In order to resolve these problems, the geotechnical properties of the St. Peter sandstones were investigated through a comprehensive research program, which included uniaxial test, triaxial test, porosity test, thin section, X-ray diffraction (XRD), and scanning electron microscope (SEM). The specimens used for the uniaxial and triaxial tests were specially prepared because of the highly friable nature of the St. Peter sandstone. Thin section, XRD and SEM were utilized to examine the effect of the microstructure of the St. Peter sandstones on its strength characteristics.

Feb 27, 2013

By Peter van Dijk, Gary Almeraris, Philip Rice

This paper describes the Contractor’s value engineering design and the construction of the Interstate I-90 highway tunnel sections under the South Station railroad yard in Boston, MA for the Central Artery/Tunnel Project, using tunnel jacking and ground freezing techniques. Three tunnel box sections were constructed and installed, with typical cross-sectional dimensions of 11.6 m x 23.8 m, and respective lengths of 50.9 m, 78.7 m and 115.6 m. A 12-compartment concrete shield was built as part of the front of each multi-sectional tunnel box structure. The jacking systems employed consisted of rear and intermediate jacking stations and up to 87 individual jacks, providing a maximum total thrust capacity of 42,300 t. The tunnel alignments pass through a geologic profile consisting of historic fill, which contains remnants of old waterfront structures, building foundations and a forest of 19th century vintage timber piles, underlain by organic sediments and marine clay. Ground cover over the tunnels is in the range of 1.8–7.6 m. The groundwater table is at depths of 1.5–3 m below surface grade. The paper discusses the techniques developed and equipment used to successfully build and install these tunnel box structures with minimal impact on the commuter and long distance railroad operations directly above the tunnel alignments. Figure 1 shows the track area at the I-90 EB and WB tunnels.

Jan 1, 2001

The more than 40,000 mining industry professionals that are expected to attend the National Mining Association’s(NMA) MINExpo International2000 trade show and conference will be treated to the exhibition’s largest display ever. The exhibit is expected to cover more than 60,385 m2(650,000 sq ft) and feature more than 1,300 exhibitors. The event is set for Oct. 9-12, 2000 at the Las Vegas Convention Center in Las Vegas, NV. Richard L. Lawson, NMA’s president and chief executive officer, said, “MINExpo 2000 will showcase everything that mining is proudest of. This is the largest premier mining exposition in the world.” MINExpo is held every four years.

Jan 1, 2000

Ceremonies for the induction of four mining industry pioneers into the National Mining Hall of Fame will be held Saturday, Sept. 13, 2008 at the Charles F. Barber Pavilion of the Museum Convention Center in Leadville, CO. This will be the 21st Annual National Mining Museum and Induction Banquet. The four inductees are Lew Eklund, 76, Carrie Jane Billings Everson (1843-1914), ?Colonel? William C. Greene (1851-1911) and Arthur L. Hawkesworth (1860-1905). Lew Eklund founded Eklund Drilling that is now based in Elko, NV. He invented many designs that play a major role in today?s mining industry. His Cyclo Blower and various sampling devices he designed helped to revolutionize gold deposit exploration by allowing mining companies to effectively sample microscopic gold. Carrie Jane Billings Everson discovered and proved a method for bulk oil flotation concentration of mineral ores, the precursor to modern froth flotation methods of minerals concentration. She patented her process in 1886. In the early 1890s, coworkers built and operated demonstration plants incorporating her bulk oil flotation process. ?Colonel? William C. Greene was responsible for the development of the great copper mining properties of Cananea, Mexico. In seven years, he went from ragged cattleman and adventurer to the greatest captain of industry the borderlands have ever seen. Arthur L. Hawkesworth was a master mechanic for Anaconda Copper. He invented the detachable drill bit. His invention generated tremendous savings for the mining industry in time, in dollars and in safer operating conditions underground. His bit?s long lasting contribution to improved mine economics is immeasurable. The 21st Annual National Mining Museum and Induction Banquet will begin with an open house and reception at 5:30 p.m. followed by the dinner and program at 7 p.m. The inductions will bring to 201 the number of mining ?greats? whose engraved photographs and biographical sketches are installed in the National Mining Hall of Fame.

Jan 1, 2008

By D. Royston

SAG mill liner development draws primarily on practical experience from SAG milling operations supported by computer-based modeling of charge motion in SAG mills and on established good design practice. Liner design needs to respond to the process aspects of mill liner action that are critical to good SAG mill performance, i.e., the impact of shell liners on the grinding action and of grates and pulp lifters on pulp discharge. In recent years, the trend in large SAG mills has been to use wide-spaced shell lifters with large lifter face angles, primarily to reduce packing and ball/liner damage, and to use larger, hence fewer, mill liner parts to reduce downtime at liner change-outs.

Jan 1, 2007

By D. Z. Mraz, R. S. Jones

Unlike in coal mines where caving methods are used, the subsidence over potash mines in Saskatchewan, Canada, is a function of gradual mining convergence. Because of the presence of high pressure water aquifers over the evaporite salt formations, the mines have to be designed as regionally stable and no caving is allowed. The extracted area converges gradually and the convergence is mainly a function of the extraction and the mining method employed. Consequently, the subsidence rate is very slow and the bridging of the over-lying strata is a considerably more important phenomenon than elsewhere. The paper evaluates a case history of convergence and subsidence in a deep potash mine in Saskatchewan.

Jan 1, 1986

The La Colosa, Colombia porphyry gold deposit is currently in the pre-feasibility stage. This large deposit has many types of gold mineralization: native gold, electrum, and tellurides. These variations in the gold mineralization lead to variability in the gold recovery. The final process flowsheet may include gravity concentration with cyanide leaching. Metallurgical testwork is utilized to identify the zones of ore that may be problematic to recover. To help select the samples that represent the fluctuating variability zones, geometallurgical models are constructed using mineralogy and geology data. These zones are then wireframed and compared to the geological and structural models for spatial correlation. Samples for the variability testwork will be selected from these different zones to identify and analyse the effect the different gold mineralization types have on the recovery. By using geometallurgy to aid in the sample selection for metallurgical testwork, the variability in the ore body can be understood and constrained to aid in process optimization.

Feb 27, 2013

By Irving D. Cohen

In order to overcome our reliance upon foreign energy sources for both crude supply and finished products, we must realize the goals proposed by Project Independence. In general this involves expanding production of existing and new oil, gas, and coal resources, utilizing and improving nuclear technology and the developing of new energy sources such as solar, geothermal, oil shale, tidal, wind and stimulation techniques. There is a continuing debate, both in the scientific community and the consuming public as to the potentiality of nuclear power generation being cost effective and environmentally and safety conscious. The development of new sources of energy does not occur overnight; it is rather a continuing effort in time and money to achieve the goal of providing energy to an ever increasing demand. The public has been accustomed to the availability of energy whenever and wherever it was needed. The era of "energy gluttony" has begun to fade into the realm of "energy awareness". Unfortunately, it required the action of another country to bring the picture that has been discussed many times in the past by energy suppliers into correct focus. Nevertheless, the public responded by conservation efforts to reduce energy wastefulness. Still, the demand for foreign importation of energy supplies is on the rise. What is our recourse? The largest known unexploited energy resource available in the United States is our coal resources. Moreover, the Department of the Interior has noted that 63 counties in Montana, Wyoming, and the Dakotas hold 60% of the nation's least expensive strip minable coal. This western coal is the most abundant and least costly Fossil Fuel in the United States. It is acknowledged that western coal is an important input in meeting the energy needs of our nation.

Jan 1, 1976

By Dianne C. Marozas

The U.S. Bureau of Mines is conducting research to evaluate the potential for developing an in situ leach mining process that will selectively extract manganese from oxide ores, leaving gangue relatively undisturbed. To accomplish this, a geochemical approach, based on deposit-specific information such as mineralogy and geology, is used to constrain the operating parameters of the system. Among the studies being conducted are (1) leaching experiments to define reaction mechanisms and kinetics, (2) detailed petrologic characterization at the microscopic scale to assess Mn distribution and leaching efficiencies, (3) deposit characterization and evaluation, and (4) development of potential Mn recovery schemes. Data from these studies are being used to develop engineering design information for an in situ mining process. Specific details of the Bureau's research project are discussed, including results obtained to date.

Jan 1, 1991

By M. Menéndez

Enhanced gravity separation appears to be one of the most promising methods for processing all types of <200-µm coal feeds and tailings. Systems based on this technology are reviewed, and the results of investigations based on C900 Multi-Gravity Separator tests conducted to assess the treatment of <200-µm, extremely difficult-to-wash coal settling pond tailings are presented. Multi-Gravity Separator processing tests of ultra-fine tailings with a high clay particle size content (22.6% <10 µm and 60.1% <40 µm) and a 69.56% ash content show that this material can be effectively treated after desliming (<10 µm) of clay-size particles to produce a coal with a 20.6% ash at a separator combustible material recovery of 69.3%. Desliming is shown to be critical in reducing coal ash content and combustible material recovery. Similar improvements are anticipated in the recovery and separation pro-cesses for other enhanced gravity separation systems from the desliming of feeds. Although not a conventional form of treating Multi-Gravity Separator data, the existence of well-defined polynomial relationships based on the product of drum shake amplitude and shake frequency relative to product coal recovery, product ash content and yields at varying wash water flows is demonstrated. Low-amplitude and intermediate- to high-frequency bed agitation are shown to produce optimum ash reduction results.

Jan 1, 2007

By Steven C. Borell

For more than a decade, changes have occurred each year that have improved the regulatory and business climate for mining in Alaska. These changes have taken place during Republican and Democratic governorships as well as when the state House of Representatives and Senate were controlled by either party. During some years, the changes have been relatively minor. In others, including the 2003 legislative session, the changes could only be characterized as massive. These improvements have encouraged exploration. This, in turn, has resulted in some major new discoveries. But Alaska is essentially unexplored and tremendous opportunities remain.

Jan 1, 2004

By S. Ersayin

In 1998, the Concentrator Modeling Center was established within the Coleraine Minerals Research Lab, Coleraine, Minnesota, to develop models for simulation of iron ore processing plants, and to assist plant operators in improving performance of their aging plants. The short-term objective was to develop necessary models for reliable simulation using conventional techniques, while the long-term objective was set as liberation-based modeling and simulation of these plants. The short-term objective was achieved in 2002 after the development of models for magnetic separators, hydro-separators and fine screens. A project funded by the U.S. Department of Energy was carried out to demonstrate the capability in improving iron ore processing at the Minorca plant. As a result of this study, a 10% improvement in throughput at the plant was obtained, and simulation became a desired tool for plant operators. A significant step in the long-term objective was reached in 2005 with the development of a liberation model. This was followed by incorporation of models capable of processing liberation data into the software. By early 2007, the Concentrator Modeling Center had the capability of performing liberation-based simulation of entire plants.

Jan 1, 2009

By S. P. Lewis, R. L. Sundeen

Most of us are aware of the ever increasing use of underground space. At the Advisory Conference on tunneling in Washington, D. C. in June of 1970, the demand for construction oriented tunneling during the 1970s was estimated at some 21,000 Km of length with an excavation volume of 675 million cubic meters. Of this total, 11 million cubic meters were forecast for underground parking. Though this is a small portion of the total, it is significant to note it represents a 280% increase over the previous decade. Other areas of unusual increase were railroad tunnels, 150%, and rapid transit tunnels, 160% (1). Faced with this increasing demand, the need for improved excavating efficiency is obvious. Great strides have been made. In Japan, for example, several new long tunnels have been driven parallel to old existing ones at costs as much as 50; under those of the original tunnels (1). This is an impressive achievement. I am certain, however, that we would all agree that even greater improvement is required. Great emphasis is being placed upon sophisticated systems which include among others, mechanical borers, thermal fracturing, and various methods of rock weakening and softening. However, in hard rock excavation the fact remains that the drill-blast method continues to be the most widely used system. Undoubtedly it will continue to be one of the most important techniques in the forseeable future.

Jan 1, 1974

The safety of personnel is the most important matter during a mine fire. However, there is not enough research on a case when a fire occurs near a shaft and the behavior of the fire gas is not well understood. Therefore, a series of experimental study using a scaled ventilation circuit model was carried out. The behavior of ventilation air during a mine fire near a shaft was investigated. The model consists of two vertical shafts, three horizontal ducts connecting the shafts and an exhaust fan from the shaft bottom. The cross section of the shaft and duct is a square of 200×200mm. The height of the shafts is 3400mm. The length of the ducts is 1540mm. The lower duct is set at the same level as the shaft bottom. The middle and upper duct are set at 750mm and 1760mm above the shaft bottom respectively. The airflow rates through the ducts can be adjusted by regulators installed in each duct. The behavior of the fire gas was measured by anemometer, thermometer, and visualized using laser light .The air was ventilated downward in both shafts before the initiation of the fire. Some amount of fire gas of high temperature rose upward gradually along the shaft wall regardless of the downward ventilation after the initiation of the fire. Then the direction of main ventilation air suddenly reversed upward in the shaft. The direction of ventilation reversed in many places in the model and the fire gas reached even the part not anticipated.

Jan 1, 2009

By Michael Jatczak

The San Vicente Tunnel Project is an 11-mile water tunnel constructed for the San Diego County Water Authority. One of the many challenges of the project included tunneling a 22,000-foot single-heading tunnel on the western half of the job in varying geology using a 3.66m (12ft) diameter open shield excavator or ?digger shield.? This paper will discuss the design considerations for the temporary liner, the tunneling, and ancillary equipment. It will also highlight the challenges faced while mining this geology, explain the methods implemented to drive this section of tunnel, and discuss the experiences while performing mechanized tunneling in an extensive and varied San Diego geology.

By K. S. Lackner, T. M. Yegulalp

We present a review of research and development for coal based clean energy systems aiming for zero emissions to the atmosphere. These systems can utilize all kinds of coal or other solid carbon sources such as tar sands as well as liquid hydrocarbons. The chemical energy of carbon is transferred to hydrogen and used in power generation, in fuel cells, or hydrogen combusting turbines. The waste products of these future power-generating systems are ash, sulfur compounds and CO2. We also summarize current and developing technologies for processing of CO2to produce mineral carbonates for permanent disposal, and associated byproducts.

Jan 1, 2003