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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 C. A. Young, J. D. Miller

The surface chemistry of the calcite/oleate flotation system was examined by in-situ FT-NIR/IRS. Spectra of combination and overtone bands of aliphatic stretching vibrations revealed gauche/trans conformational changes that occurred solely as a function of temperature. The conformational changes were attributed to the simple "melting" behavior associated with phase transitions. It was concluded that chemisorbed oleate at calcite surfaces is gel-like at temperatures below 22oC, resembles a coagel between 22oC and 31oC, and becomes micelle-like at temperatures above 31oC. By comparison, chemisorbed oleate at fluorite surfaces also undergoes these phase transitions but is additionally dependent on adsorption density. The conformational changes were observed at high chemisorption densities (> 2.0x10-10 mol/cm2) and attributed to molecular forces, primarily van der Waal's interactive forces, among neighboring chemisorbed oleate molecules. Similar analysis of in-situ FT-NIR/IRS spectra of surface-precipitated calcium dioleate at calcite surfaces did not exhibit this behavior thereby confirming that surface-precipitated calcium dioleate remains in an all-trans conformation. The results help explain why surface polymerization is not observed at calcite surfaces but is observed at fluorite surfaces.

Jan 1, 2002

By John Corcoran

INTRODUCTION Content of this Report The 1300m long twin-bore 8.1m diameter Airside Road Tunnels (ART) were excavated beneath the busy taxiways and stands of Heathrow Airport between 2002and 2003. The tunnels were fully completed and handed over to the client for use early in 2005. This paper will describe the purpose of the tunnels, and the measures put in place to minimize the impact of construction on the daily activities involved in running an international airport. Terminal 5 Construction Heathrow Airport is the busiest international airport in the World, with a current capacity of circa 67 million passengers per year, based on existing infrastructure of4 passenger terminals, 1 cargo terminal, 2 runways and 170 aircraft stands. Terminal 5(T5) is being built to increase Heathrow’s passenger capacity by providing the following: 12 additional aircraft stands through redevelopment of the south apron area, in the autumn of 2004 A main terminal building (T5A) and a first satellite (T5B), and 43 additional stands by the spring of 2008, most of which will be able to receive the new generation large aircraft (Airbus A380) A second optional satellite (T5C) by year 2010 A third optional satellite (T5D) by year 2015 The total value of the project is approximately 4.2 billion pounds for the main phase of the works spanning from 2000 to 2007. Purpose of the Airside Road Tunnel The ART has been constructed to support the internal road traffic of the airport between terminals, aircraft stands, runways and taxiways, for passenger buses, service and technical vehicles. The majority of the traffic will be buses transporting passengers between the terminals and their aircraft.

Jan 1, 2005

By E. D. Attanasi, J. H. DeYoung

Mineral exploration activity in the US suffered through another depressed year in 1984. And continued strength in precious metals (and possibly industrial minerals) exploration failed to make up for declines in other minerals. 1984 offered little solace for the explorationist. But some new data on mineral exploration provided better statistics for analysts of US mineral exploration trends. The Society of Economic Geologists (SEG) published data from its survey of 1980,1981, and 1982 exploration by US and Canadian companies - 96 companies responded (Barber and Muessig, 1984). In addition, a Mining Engineering (April 1984 p. 345) article by Emerson and Ivosevic presented their data on annual exploration expenditures in the US for gold and for all minerals from 1961 through 1983. A review of 1984 domestic exploration and development activities reported in several industry journals indicates that almost 90% of those projects were directed at gold and silver deposits. Statistics on 1984 exploration expenditures are not available. But some industry observers believe that precious metals accounted for an even larger share of industry's exploration budget in 1984 than in 1983. According to the data of Emerson and Ivosevic (ME, April 1984, p. 349), gold exploration expendi-

Jan 5, 1985

By P. Ulrich, V. Svalbonas

The early to mid 1980s was a period of mining consolidation, and many senior design engineers retired from the mill industry. Similar conditions have existed in the last few years. This creates a loss of a tremendous amount of experience. This paper is a look back by two senior mill designers who survived the dips in both time periods. From a continuous design practice of over 25 years, mill designs and fabrication practices are surveyed with a view of identifying what works, and is necessary, and what doesn’t, or is not necessary, in the creation of a safe, economic, long-lived grinding mill.

Jan 1, 2001

By B. Anameric, S. K. Kawatra, K. B. Rundman

The iron nugget process is an economical, environmentally friendly, cokeless, single-step pig iron making process. Residence time dependent process requirements for production of pig iron nuggets at a fixed furnace temperature (1425 C) were investigated. Three chemically and physically different products were produced after complete reduction to iron, depending on the residence time in the furnace. These products were direct reduced iron (DRI), transition direct reduced iron (TDRI), and pig iron nuggets (PIN). The increase in the carbon content of the system as a function of residence time was detected by optical microscopy and Microhardness measurements. Sufficient carbon dissolution for the production of pig iron nuggets was obtained after 40 minutes residence time. The pig iron nuggets produced had chemical and physical properties similar to blast furnace pig iron. They were liquid state products and slag was completely separated from the metal.

Jan 1, 2005

By S. Roy

Soft laminated iron ore (SLO) having a higher hematite content and Martite goethite iron ore (MGO) having a higher goethite content were subjected to detailed characterization and beneficiation. The present research was designed to investigate if these abundant, low-grade ores can be enriched adequately using standard industry techniques. No significant enrichment of the ores using jigging operation on the coarse (-3,200 +595 mm) size fraction could be achieved. Good liberation was only attained in the 150 to 300 mm particle size range in both cases. Desliming enriches the ground ores significantly. The effect of the feed size on the separation efficiencies of the ground ores were studied using flowing-film concentration on a Wilfley table. Better enrichment is obtained in the case of 150-mm sized feed by tabling. The grade of SLO is improved from 56.14% to 66.51% Fe, while the Fe content of MGO is enriched from 55.16% to 65.83%. Substantial rejection of alumina and silica is also achieved. Due to the friable nature of MGO and the higher goethite content in it, the loss of Fe in the form of ultrafines is greater in this case compared to that of SLO.

Jan 1, 2009

By Robert Harris, David Duncan

The Samira Hill gold mine represents the first commercial gold project for the landlocked country of Niger in West Africa. It began production in October 2004 as the result of over 10 years of exploration and development work. There were several administrative, social and technical challenges that had to be overcome to realize the successful development of the project. The Samira mine is located on the geological structure known as the ‘Samira Horizon’ which is developing as a promising district for additional discoveries and other mine developments.

Jan 1, 2005

By G. L. Dollinger, J. P. Kindsvater, J. A. Gibson

DESIGN AND DEVELOPMENT OF A MOBILE MINING MACHINE INTRODUCTION Until recently, developing tunnels in hard rock has been accomplished either by the drill and blast method or by using large tunnel boring machines. Combining the flexibility of drill and blast with the safety, efficiency and productivity of a TBM has been the objective of mining machinery producers for many years. In 1979 The Robbins Company began developing a new type of tunnel boring machine called the Mobile Miner to meet these objectives. The development and testing of the Mobile Miner is the subject of this paper. CURRENT MINE DEVELOPMENT METHODS Both the drill and blast method and the use of a TBM have notable advantages and disadvantages. The drill and blast method, for example, allows much more flexibility, requires less setup time and has a lower initial cost than a TBM; however it requires the use of high explosives and blasting has a disrupting effect on the rock surrounding the development. A TBM, on the other hand, is safer to operate, more efficient, more productive and produces smooth tunnel walls without disturbing the surrounding rock. In longer straight drifts it will easily out distance the drill and blast method. The TBM, however, is limited to boring a circular cross section tunnel which must then be modified if a flat floor is required. It also has a higher initial cost and an extended setup period.

Jan 1, 1985

By B. Spigarelli

Carbon dioxide sequestration by conversion to carbonates has become a promising option for CO2 storage. Experiments were conducted to determine the feasibility of CO2 sequestration at ambient conditions using a Ca-rich industrial waste in a carbonate solution. The Ca-rich industrial waste used in this study was lignite fly ash. Fly ash was chosen because it is cheap, available near large CO2 point sources, already in powder form, and reactive due to amorphous properties. In the experimental set-up, CO2 absorption was inferred by monitoring feed and exhaust gas CO2 concentrations. The addition of an alkali to a fly ash-distilled water solution provided a 50% increase in CO2 absorption of the solution. Absorption time also increased by 50% compared to a fly ash-distilled water solution. TGA analysis was used to determine the extent of CO2 sequestration in the carbonate form. At a liquid to solid ratio of 20:1, the conversion of ?free? calcium to carbonates was 75%. A CO2 balance on the system concluded that at the current operating conditions 42% of the total CO2 fed to the system was sequestered in the carbonate form. SEM-EDS analysis of the fly ash particles before and after reaction with CO2 indicated that the carbonate compound being formed was calcium carbonate. The analysis identified rhomboidal structures on the surface of the fly ash particles after reaction with CO2, but not before. These rhomboids are characteristic of calcium carbonate formation and they had higher Ca, C, and O concentrations than the host spheres, suggesting calcium carbonate formation.

Jan 1, 2012

By C. Gherghel

The planning and operation of ventilation network systems for uranium mines require special considerations since ventilation is the primary technique of controlling ambient concentrations of radon progeny. The major environmental challenge facing the ventilation engineer is the requirement to dilute radon progeny to below the Working Level Month per year of worker exposure required by law. The application of large airflow volumes and the utilization of low residence times constitute some of the factors considered by the design engineer. Good mine planning and sequencing are also critical for protecting the health of miners. The mine ventilation must have such characteristics as flexibility, high air distribution efficiency, rapid air transit times, zero recirculation and no short-circuiting. A well established maintenance program for all ventilation appliances must be in place to guarantee control of the distribution system. Real-time monitoring systems permit assurance the adequate quality of air is delivered to working places. A case study for an operating mine is used to demonstrate how the ventilation system is successfully managed and operated using the above concepts.

Jan 1, 2009

By W. Lin, M. J. McPherson

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Feb 24, 1997

By Steve Kral

President Bush’s National Energy Program and his Clear Skies Initiative both emphasize the use of coal to help meet the nation’s growing energy needs. And why not? Coal is currently responsible for more than 50 percent of the nation’s electricity generation. That fact, though, seems to be lost on policy makers, the environmental community and the public. Critics of coal advocate the increased use of renewable energy sources and the increased use of natural gas. Renewables, though, are only capable of generating a tiny fraction of the power required. Natural gas is expensive. And natural gas production cannot keep up with demand, especially given the nation’s increasing energy needs.

Jan 1, 2003

By C. L. Kosmoski

The mining industry faces many workplace hazards that are a threat to human health and safety. The Bureau of Labor Statistics has found that employees in coal mining are more likely to be killed or sustain an injury or illness than workers in private industry. These injuries are also likely to be more severe (Bureau of Labor Statistics, 2007). In recent years, coal mining injuries have attained national attention due to highly publicized disasters. Despite these threats to worker safety and health, the U.S. relies on the mining of coal to meet its need for electrical power, with42% of electricity in the U.S. generated through the burning of coal (U.S. Energy Information Administration, 2012b; United Mine Workers of America, n.d.). Furthermore, the production of coal continues to increase and reach record levels every year(National Mining Association, 2012; U.S. Energy Information Administration, 2012a). For this reason, the coal mining industry must continue to find ways to protect its workers while maintaining productivity. One potential approach to protecting workers while maintaining productivity is through improving the safety culture at coal mines. In order to achieve this culture, operators, employees, the inspectorate, etc. must share a fundamental commitment to safety as a value. This type of culture is known in other industries as a ?safety culture? and can be defined as the characteristics of the work environment, such as the norms, rules, and common understandings that influence facility personnel?s perceptions of the importance that the organization places on safety. Fundamental to improving safety culture within an organization is understanding the existing safety culture; improvements cannot be made without first elucidating areas that require improvement. This manuscript details the process undertaken by researchers at the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) to assess the safety culture at five underground coal mines across the United States. The purpose of this manuscript is to introduce the mining industry to a multi-methodological approach to safety culture assessments. Further, it is the goal of this manuscript to highlight the value of including both quantitative and qualitative methods into safety culture assessments in order to obtain the most comprehensive view of an organization?s safety culture. Because this manuscript focuses solely on the methodology implemented, data and results obtained during the five safety culture assessments will not be presented in this manuscript, but will appear in a future publication.

Feb 27, 2013

By J. S. Young

During 1975, the Reclasource Corporation constructed and commissioned a plant for the recovery of mill scale, coke breeze, blast furnace dust, blast furnace sludge and basic oxygen furnace dust at the site of Crucible Alloy Division, Midland, Pennsylvania. The Reclaform Process was employed as the criteria for plant design. This Process takes the solid in-plant fines as listed above, commonly found in integrated steel mills, sizes and forms them through the use of a carbonaceous binder briquetting system and cures the binder through a final heat-treating step. 15,000 tons of Reclaform briquets have been tested in the Crucible blast furnace in several campaigns structured to assess material handling properties, burden feasibility and finally culminating in an iron and carbon assessment campaign. Data are presented from the records of the blast furnace operation and conclusions are drawn that both iron and carbon utilization have been demonstrated.

Jan 1, 1977

By D. J. Dodds, W. L. Schroeder

INTRODUCTION The plate loading test is a simple, useful tool in rock mechanics. The test consists of applying load to a rock surface and noting the resulting deflections. Plate loading tests are typically used to obtain modulus of deformation and related material properties, but can also provide information on blast damage and in situ stresses (1). Properties obtained are of course dependent on test procedure and test environment . In order to eliminate extraneous results it is essential that the interrelationship between the physical test environment and various rock properties obtained be thoroughly understood. Test interpretation is based upon elasticity methods, and the general assumptions made during analysis which include the following: 1. The rock is homogeneous, isotropic, elastic and continuous. 2. The stress is induced in a semi-infinite solid. 3. The plate is perfectly rigid or completely flexible. 4. Rock properties are independent of in situ stresses. 5. The plate and rock surface are smooth and parallel.

Jan 1, 1974

By D. X. Tang, G. Wilson, S. S. Peng

Design and implementation of a roof bolting plan requires reliable geotechnical information of strata, such as rock strength, and locations of interfaces and voids/fractures. The drilling parameters obtained during normal roof bolt installation cycle provide a fast and economic way to gather information on the geological structure within the bolted horizon. The purpose of this research project is to develop a method for identifying the geological features in the mine roof strata based on drilling parameters of roof bolter. The criterion for void/fracture prediction has been developed and proven valid. This paper focuses on the estimation of the strength of roof strata by using drilling parameters. Based on the results of a series of underground and laboratory tests, feed pressure is found to be the most sensitive parameter when the strength of roof strata changes. Moreover, it was also found that both penetration rate and rotation rate have obvious impact on the magnitude of feed pressure. Based on these findings, the criterion for the estimation of roof strata strength has been developed using the relationship among feed pressure, penetration rate and rotation rate and implemented in MRGIS.

Jan 1, 2006

By Jim Richards, Eli Choueiry, Brett Robinson, Amanda Elioff

The Los Angeles Metro Gold Line Eastside Extension (MGLEE) extends Metro’s light rail system to the densely populated and growing East Los Angeles communities. Much of the 6 mile alignment consists of at-grade track, but the project also features a1.7 mile underground segment in cut-and-cover and twin-bored tunnel structures. In light of past experiences with open shield construction, The Metropolitan Transportation Authority (Metro) specified, for the first time, use of Pressure Face Tunnel Boring Machines (TBM’s) to advance tunnels through soft ground. This paper describes the history of the tunnel design, construction management, and construction methods adopted that resulted in successfully completing the tunneling segment.

Jan 1, 2007

By Martin Herrenknecht

Tunnel boring machine (TBM) development continues to take on not only larger diameters, but also more difficult ground conditions. Ground conditions consisting of unstable faces with water pressures up to 15 bar have required innovative design approaches. A systems approach has been required to produce tunneling machines that can safely excavate the tunnel in an efficient, cost-effective manner that stresses production and labor saving approaches. This article reviews the current design developments and present recent projects where these most recent principles have been applied. The world?s growing population and rapidly proceeding urbanization are boosting an enormous demand for new and high-capacity infrastructures to secure the mobility of goods and people. Densely populated areas face the challenge of providing efficient traffic infrastructure such as a modern public transport system. At the same time, the maintenance and modernization of supply and disposal structures for water, sewage, energy and communication are essential. Last but not least, are supra-regional transportation routes such as long distance water diversion schemes. All of these projects are as demanding and are characterized by a tight time schedule. In this context, the demand for efficient tunnels for traffic and utility lines is increasing, as new infrastructures often leads underground because of limited space above ground. Also, tunnels are the obvious choice to cross natural barriers like mountain ranges. To handle the complex and variable geological conditions and other constraints, such as low overburden, high water pressure or long tunnel drives while facing increasing demand of a quick completion of a project, mechanized tunneling sets standards regarding safety, profitability and environmental protection in traffic tunneling projects as well as in the trenchless construction of utility tunnels. Different machine types and working principles have been developed to master various geological and hydrogeological requirements. Continuous activity in research and development leads to constant improvement of the mechanized tunneling process.

Jan 1, 2008

By Paul H. Johnson

Resource Engineering and Development, Inc. is desigining and building a portable 150 to 225 tpd, flotation-cyanide leach plant with unitized, skid-mounted components. This plant design, with its portability, low capital investment, and high recovery of silver and gold from many partially oxidized ores, is well suited to treat many small, highgrade deposits, old waste dumps, and old mill tailing piles. A description is given of flotation and/or cyanide leach tests run on 18 partially oxidized, newly mined ores; waste dump materials; placer slimes; and old mill tailings.

Jan 1, 1981