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By J. Chae, D. Pecha, R. Andrews

The Henderson/ML King CSO Project is a major combined sewer overflow (CSO)reduction project for the Department of Natural Resources and Parks of King County, Washington. The central element of the project is the 3100 lineal feet long, 14'-8"diameter 42nd Ave S Storage/Treatment Tunnel. During the course of the project, the owner and consultants evaluated numerous elements of the tunnel including the alignment, geotechnical conditions, tunnel liner, and settlement monitoring requirements. The contractor utilized innovative shaft construction methods for the tunnel portals, and adhered to strict contract requirements in successfully constructing the tunnel. This paper provides an overview of the design and construction elements of the 42nd Ave S Storage/Treatment Tunnel that led to the successful completion of the project.

Jan 1, 2005

By Sabina Brady

Investment in the ferrous sector between 1981 and 1985 will total about $9 billion, or 7.6% of the state budget for capital assets. The money will primarily go to complete the first stage of the Baoshan Iron and Steel complex and to increase steel production by 3 Mt* (3.3 million st) and seamless tubing by 0.5 Mt (551,000 st). Investment in 1983 will be about $3.5 billion, a 28% increase over 1981. Although data on nonferrous investment is less specific, the Chinese announced early this spring that the country's investment would be 2.6 times greater than the average spent during the previous five year plans. Geological surveying will also be stepped up. The Ministry of Geology and Minerals recently announced it will incorporate a search for metal and mineral resources into its second round of oil and gas surveys. The Sixth Five-Year Plan desig¬nates some actual production targets. Steel is to increase to more than 72 Mt (79.4 million st). The country's production of 10 priority nonferrous metals - aluminum (and bauxite), copper, lead, zinc, nickel, tin, antimony, mercury, magnesium, and titanium - is to increase 12.7%. Top priority is to develop aluminum production. Renewed efforts are to be made to develop gold and silver production and to increase rare earth and rare metal production. By April 1983 when the China Nonferrous Metal Industry Corp. was established, some five months after publication of the Five-Year Plan, the goals for nonferrous development had already been upgraded and changed to include: • development priority status equal to that of coal's; • an increase of more than 150% in the 1985 projected production level for the 10 top nonferrous metals (a move from the Sixth Five-year Plan's production increase of 12.7% to one of 34%); and • modification of the top 10 nonferrous metals list to include tungsten, molybdenum, and rare earths. Aluminum, copper, lead, and zinc maintained primary importance, while mercury, magnesium, and titanium were deleted. It is likely that the modification will be taken one step further and titanium will be substituted for antimony. China has already indicated its intentions to stabilize rather than expand its antimony industry, while press reports play up the titanium industry's importance to the country's development. In addition, the China Nonferrous Metal Industry Corp. announced that it expects to register a progressive annual increase of 4% in foreign currency earnings through export. China's nonferrous development efforts, therefore, appear two-pronged. First, the country's efforts will be directed toward self-sufficiency in its four major process and primary metals - aluminum, copper, zinc, and lead - and a number of other nonferrous metals that are in increasing demand by its light industry sector. At present, 96% of China's non¬ferrous consumption is composed of aluminum, copper, lead, and zinc. Substantial portions of that must be imported to meet rising demand. Second, efforts will concentrate on those metals that can be developed the fastest and are in "urgent demand" on the international market. Metals such as tungsten, tin, molybdenum, titanium, nickel, and rare earths will be given freer use of foreign capital and technology to increase production levels and raise quality. Examples of some projects in the area include upgrading the country's carbide industry and developing new high speed and tool steels to meet international standards. Foreign involvement and sales have been reported in each area, particularly with regard to sales of deposition equipment and presses by Swiss and West Ger-

Jan 8, 1983

By Harry R. Price, Behrooz Tahmasbi, Charles J. Roarty

The 2,408 meter (7,900-foot) long Middle Rouge Parkway Interceptor Extension varies in size from 1.52-meter (5-foot) to 2.36 meter (7-foot 9-inch) inside diameter. Most of the sewer was constructed in tunnel through fine sands and silts. Piping of these soils through the concrete liner eventually resulted in a loss of soil support, settlement and/or severe distress of the sewer, and the formation of several sinkholes. The repair and restoration was generally performed in the sewer and included cast-in-place concrete, shotcrete, cured in place pipe, soil stabilization, cement grouting, dewatering, and chemical grouting. As a part of the work, temporary pump stations and flow diversions were required to perform the work while minimizing discharges to the adjacent Rouge River.

Jan 1, 2007

By R. E. Moore

Refractories are unique ceramic materials, which are used in large quantities in steel making furnaces, metal smelting vessels, and glass melting tanks. They are required to possess high thermal shock properties and good slag corrosion resistance as well as creep resistance at high temperatures. Therefore, they are made from very refractory minerals such as lime, periclase, corundum, spinel, and zirconia. Slags are vitreous materials produced as a residue in steel refining processes. They cover a wide range of compositions and may contain pure oxides, silicates, and sulfides as well as fluoride phases depending on the melting and smelting processes. These minerals exhibit spectacular cathodoluminescence color under electron bombardment; therefore, cathodoluminescence (CL) microscopy is found to be a superior technique for the characterization of refractory corrosion by slags. Examples included in this study are (1) reaction of fluorine containing mold slags with ZrO2-C nozzle refractories promoting crystallization of the Cuspidine, Ca4Si2O7(F,OH)2, (2) corrosion of fusion cast refractories in TV panel glassmaking furnaces and formation of glass defects, and (3) reaction of spinel based castable refractories with copper smelting slags.

Jan 1, 2001

By Syd S. Peng

Coal mine ground control is the science of the application of rock mechanics principles to coal mining operations. More acceptance of ground control techniques by the US coal mining industry has been seen in the 1980s. It has been demonstrated many times that a proper ground control design is key to a successful coal mining operation. However, numerous in-mine applications of various ground control techniques by the author indicate that cur¬rent techniques need improvement. The biggest problem in coal mine ground control is that miners are dealing with materials of rapidly varying properties and occurrence. And only the exposed surface can be identified positively. Thus, in attempting to solve the ground control problems, many unknown factors are assumed. Some of these problems deriving from such assumptions are discussed here. Coal pillars There are two types of coal pillars - barrier and chain pillars - depending on the purpose. Barrier pillars are those located between panels or sections or mines. Their objective is to isolate the mined-out effects of one from the other. Chain pillars are characteristic of room-and-pillar mining. They are designed to support the overburden load and protect the surrounding entries and crosscuts. Pillar design is the most popular and, frequently, the only ground control technique employed by coal operators for mine design. There are many pillar design formulae available (Bieniawski, 1983; Peng, 1986). Nearly all consider both size and width/height effects. Specifically, pillar strength decreases with increases in pillar size and increases with increase in the ratio of width to height. However, the manner of those changes varies with investigators. Consequently, the pillar size determined varies considerably from investigator to investigator. And the variation grows much more pronounced as the seam depth increases (Fig. 1). The question, then, is which one should be used? One may say each formula is developed for a particular coalfield. A particular formula may have been used to design a pillar, which has not failed. Does that mean it was over designed? Not necessarily, because no one can confirm its stated "safety factor." Recent case studies (Peng, 1986; Tang and Peng, 1988) show that all pillar formulae are too conservative for chain pillar design in room-and-pillar mines due to the following two problems: • Uncertainty about in situ pillar strength. All formulae employ uniaxial compressive strength of selected samples tested in the laboratory and scaled to that for underground pillars. The scaling factors are not well proven. In situ testings by Bieniawski (1969) suggested that 1.5 m (5 ft) pillars are representative of in situ pillars that, after being tested in various US coal mines, are not universally applicable. • Uncertainty about the actual loading on the pillar. The most frequently used tributary loading theory defines the loading as total overburden weight tributary to each pillar (from roofline to surface). This is too conservative when it applies to coal measure rocks. The overburden consists of layered strata of different stiffness. Many stiffer strata will self-support over small roof spans. Depending on the location of these strata above the coal seam, it will reduce pillar loading in various proportions. It follows that total structural analysis using, for instance, finite element method is more appropriate. It can take into account the interaction of roof and floor strata with coal. This has been demonstrated by Peng et al. (1986,1988) on several case studies. However, the validity of the finite element structural analysis depends on the accuracy of in

Jan 1, 1989

By Wilfred P. Schmoe

Introduction An integrated oil company has two options in approaching strategic planning. It has to decide whether it is in business for the long-term. I state this in all seriousness. Those who help manage public companies have the responsibility of good stewardship of other people's money. We must decide whether continued investment in our basic business will generate a reasonable rate of return. With a world surplus of petroleum production capacity, and continuing downward pressure on prices, this question should be addressed by all oil companies. And a positive answer is not necessarily a foregone conclusion in all cases. The decision should be made based on proven competence in finding and developing petroleum reserves on a cost-competitive basis with other producers, and on a frank analysis of future prospects. This should include a realistic assessment of the projected rate of return on specific investment projects. If a company did not pass these tests, its strategy could take one of four paths. Diversification First, it could diversify. But recent history suggests that oil companies are not good at managing other businesses. Second, it could seek a buyer for its business at the optimum return for its owners. Third, it could sell its assets on a piecemeal basis. And, fourth, it could adopt a longer-range plan of self-liquidation by living off current recoverable reserves. In other words, by not investing in exploration and development, it could maximize short-term profit and pass the money back to shareholders in the form of dividends. The Conoco component of DuPont has a below-average cost of finding petroleum, a good track record of efficient production, and a full plate of projects that pass the test of return-on-investment. In short, Conoco is in business for the long-term. That fact, in itself, determines at least one key element in strategy. This is to extend the life of the petroleum reserve base while at the same time maintaining maximum efficient rates of production to provide a strong cash flow. A company that is able to maintain a strong reserve base will ultimately see the value of those reserves escalate as world oil supplies tighten. Our planners expect this tightening to occur within the next decade as demand grows and production in non-OPEC areas of the world begins to decline. An exploration program tailored to meet the requirements of reserve replacement and current production should have two basic parts. The first is relatively low-risk exploration in proven oil provinces. This is augmented by

Jan 6, 1985

By Ian Farmer, Nigel Glossop, Philip Garritty

Performance of tunnel boring machines - usually expressed in terms of penetration per revolution - is determined by relations between machine thrust and torque, head diameter and rock strength. It can be shown that for a given machine power and head diameter there is only one rock strength at which the machine performs optimally. In weaker rocks the available torque limits performance and in stronger rocks, the available thrust. Performance data shows that, historically, machines have been designed to cut weaker rocks. Optimization of thrust is required to improve performance in stronger rocks.

Jan 1, 1987

By A. Noble

Traditional simulations of mineral processing circuits are solved by straightforward numerical techniques which require iteration to accommodate recirculating loads. Depending on the complexity of the simulated circuit, this solution technique can be inexact, computationally intensive, and potentially unstable. In this communication, an alternate calculation approach is presented, wherein an exact analytical solution is determined as a function of the individual units? separation probabilities. All the stream data, including recirculating loads, may be solved simultaneously, negating the need for iteration. Furthermore, with an analytical solution available, circuit analysis may then be utilized to diagnose the relative separation potential of the circuit. By integrating these tools, the authors have developed a software package for evaluating circuit configurations. This paper presents the theory, development, and limitations of the software?s methodology along with industrial examples which highlight the tool?s applicability to industrial circuits.

Jan 1, 2012

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

Twenty field-scale tests were conducted in a 28 MW pulverized coal power plant in Healy, Alaska, to examine mill power consumption in relation to coal grind size. The intent in this field-scale study was to verify if grind size truly impacted power consumption by a detectable amount. The regression model developed from the data indicates that grind size does impact mill power consumption, with finer grinds consuming significantly more power than coarser grinds. However, other factors such as coal hardness (i.e., the lower the Hardgrove Grindability Index, or the harder the coal, the higher the power consumption) and mill throughput (i.e., the higher the throughput, the higher the power consumption) had to be included before the impact of grind size could be isolated. It was also observed that combining amperage and flow rate into a single parameter, i.e., specific amperage, hurt modeling. Cost analysis based on the regression model indicate a power savings of $19,972 per year if the coal were ground to 50% passing 76 mm rather than the industry standard of 70% passing 76 mm. The study also demonstrated that size reduction constituted a significant portion of the power consumption.

Jan 1, 2008

By R. Q. Honaker

Dense medium processes are used to clean over 50% of the coal that is fed into preparation plant facilities worldwide. The dense medium is formed using ultrafine magnetite which is recovered after the cleaning step using drain-and-rinse screens and magnetic separators. Despite the high efficiency of the recovery system, magnetite losses of around 0.5 to 1.0 kg/ton are common. Considering the recent escalation of magnetite to around $300/ton, an alternative source of magnetic material from coal combustion bottom ash has been investigated. A relatively low cost recovery system has been developed. Dense-medium tests using the bottom ash magnetics revealed a high level of efficiency as indicated by probable error values around 0.03 over the range of medium densities investigated. The results from both the recovery and coal cleaning efforts will be discussed in detail.

Jan 1, 2009

By R. P. Sloan, A. S. Whitford

In November 1999, CCI's Empire Iron Mining Partnership and MinnovEX Technologies Inc. developed an expert system for advanced control of their Empire IV Grinding Section. Empire IV is comprised of three autogenous Primary Mills and six autogenous Pebble Mills, with a single Pebble Crusher and high pressure Roll Press. The challenges of controlling and optimizing three distinct grinding lines that are inter-woven by a pebble crushing circuit were met with innovative and unique solutions. This paper will detail the approach employed at Empire and will focus on the aspects that make this application unique.

Jan 1, 2001

By Pat Wilmoth, Joseph P. Gildner, Dan Nowak, Shane Yanagisawa, Don Z. Painter, Gordon F. Revey

Frontier/Traylor is presently completing construction of twin tunnels for the Tri-County Metropolitan Transit District of Oregon’s (Tri-Met) westside lightrail system. The tunnels are each 4,550 m (14,935 ft) in length and 6.48 m (21.29 ft) in diameter. The 1/3 of each tunnel was driven from the west portal using drill and blast methods and the remaining 2/3 was driven from the east portal using a TBM. The paper describes: The difficulties encountered by the TBM mining the weathered Columbia River Basalts. The execution of drill and blast work despite challenging ground conditions, stringent noise and vibrations specifications, and public relations problems. The excavation and lining of the Washington Park Station 79 m (260 ft) below the park zoo.

Jan 1, 1997

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 R. J. Lytle

INTRODUCTION Prior to excavation in soil and rock, it is useful to know the subsurface structure. This is important information both for safety and for equipment scheduling reasons. It is useful to know whether parts of the subsurface might be potentially troublesome or of different character than is generally thought present. By using geophysical probing, it is possible to infer the location and size of these unusual regions. The ground structure is commonly estimated from core samples taken from boreholes. These cores give a detailed knowledge of the structure in the borehole. However, knowledge of the structure exterior to the borehole can only be extrapolated from core data. By using seismic and electromagnetic cross-borehole geophysical probing, remote probing can be used to sense the region exterior to boreholes. A recent advance has significantly improved the state-of-the-art for defining the ground structure between boreholes. This new procedure utilizes large amounts of data and provides a detailed picture of the subsurface. The data processing algorithms used are similar to those in medical imaging of the human body using x-rays, a science called x-ray tomography. This imaging of the ground is called geotomography, which is a shortened acronym for geophysical tomography. Several examples of geotomography applied to imaging ground structure are presented. Our approach has been to probe the ground with electromagnetic and seismic waves. We map the region of interest with signals transmitted between multiple source and receiver pairs lowered in boreholes on opposite sides of the region (Figure 1). The received signals vary according to the transmission properties of the media

Jan 1, 1979

By E. Siami-Irdemoosa, S. R. Dindarloo

"Pareto analysis was used to investigate the failures database of a Hitachi EX1900 hydraulic shovel over one year of continuous operation. The hydraulic system and hydraulic links, hoses and piping were identified as the most critical system and subsystem, respectively. A three-parameter gamma distribution function was identified as the best fit for a probabilistic modeling of the time between failures (TBFs). This distribution was used in a Monte Carlo reliability analysis of the hydraulic system. Autoregressive integrated moving average (ARIMA), within the context of a time series analysis of the TBFs, was proposed as a viable alternative to the traditional technique of distribution fitting. The mean absolute percentage error (MAPE) metric was used to compare the two models. The MAPE value that resulted from the ARIMA was 66 percent smaller than that from the traditional technique in predicting the TBFs.Resumen ¦ Se usó análisis Pareto para investigar la base de datos de fallas de una pala hidráulica Hitachi EX1900 durante un periodo de un año de operación continua. Se identificó al sistema hidráulico y a los enlaces hidráulicos, mangueras y tuberías como el sistema y subsistema más importantes, respectivamente. Se identificó una función de distribución de tres parámetros gamma como el más apto para un modelado de probabilidades del tiempo transcurrido entre las fallas (Tabes por sus siglas en inglés). Esta distribución fue usada en un análisis de confiabilidad Monte Carlo para un sistema hidráulico. El promedio de movimiento integrado auto-regresivo (ARIMA por sus siglas en inglés), dentro del contexto de análisis de serie temporal de los TBFs, fue propuesto como una alternativa viable a la tradicional técnica de ajuste de distribución. Se usó el porcentaje de la media absoluta de error (MAPE) para comparar los dos modelos. El valor MAPE que resultó de la ARIMA fue 66 por ciento menor que el resultado obtenido con la técnica tradicional de predicción de TBFs."

Jan 1, 2015

By C. Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,500 tons of ore per day with an average gold grade of 0.34 opt. The mine has a large horizontal extent of 2,500 feet by 500 feet and a vertical extent of 20 to 200 feet. Based on the characteristics of the ore bodies, a long-hole stope and cut-and-fill mining methods are used at the deposits which are divided into several mining zones. Cemented rock fill (CRF) is used as the backfill in the open stope. CRF design includes the aggregate design, the ratio of cement and fly ash design, and strengths for the long-hole stope and cut-and-fill. In the aggregate design, the particle size distribution is one of the most influential aggregate characteristics in determining how it will perform as a basic backfill material. Gradation helps determine durability, porosity, cement and water requirements, strength, and shrinkage. To cut the backfill cost, fly ash usually is added into the binder to replace some part of cement. However, adding fly ash can affect the strength of the backfill. The reasonable percentage of fly ash is also important for making a good and low cost backfill. Based on the different mining method, the different backfill with different strength is designed. A systematic quality control procedure for aggregate and backfill is followed. After four yeas application, CRF system in Leeville achieved very good results.

Jan 1, 2011

By M. A. Trevits

The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), is conducting research to test, evaluate, improve or modify coal mine fire-fighting strategies and methodologies through large-scale tests. Since wood is the second most abundant fuel available during a coal mine fire, it was decided that series of large-scale wood crib fire tests were needed to measure the products of combustion and to observe the capability of commonly available direct application fire suppression equipment, namely, fire extinguishers, water and gas-enhanced foam. This paper discusses the wood crib fire tests, provides insight into the products of combustion and describes observations made during the application of the fire suppression agents.

Jan 1, 2009

By Thomas P. Kwiatkowski, Joginder S. Bhore, Christopher D. Orlandi, Jose Velez

Three case histories of successful TBM tunneling for New York City Water Tunnel No. 3 are presented. The tunnels, costing about one billion dollars total, are the 5-milelong, 18'-11" OD Brooklyn Tunnel; the 5-mile long, 23'-2" OD Queens Tunnel, and the9-mile long, 12'-4" OD Manhattan Tunnel. The three tunnels are the first major tunnels constructed in New York City rock utilizing the TBM method of construction. This paper describes and compares the three tunnel projects in terms of geology, construction methods, TBM’s, rock and groundwater behavior, rates of advance and other performance data, and challenges and solutions encountered during the projects.

Jan 1, 2007

By Michael Stanwood

Project feasibility no longer involves just technical and economic viability-today's feasibility study must include environmental, regulatory, and political considerations as well. While the US now appears at least somewhat committed to developing synthetic fuels, including oil shale, it is the environmental issues, rules, regulations, and guidelines that will play the major role in determining the timing, magnitude, and overall scope of synfuel development in the coming years. The key environmental obstacle affecting oil shale development is uncertainty. Although oil shale may be the most environmentally studied "new" technology in the world, little is known with much degree of certainty about potential environmental consequences of one full-scale commercial facility, or the effects of a massive development effort in a relatively pristine and sparsely populated area. Other primary environmental uncertainties include: • Environmental compliance costs and their effects on investment decisions; • The reliability and acceptability of anticipated pollution control technologies; and • The confusing, time-consuming environmental regulatory framework, which requires more than 100 permits, clearances, and reviews before development occurs. This discussion will focus on the latter uncertainty, and will describe he current status of potential constraints to oil shale industry development in five areas: water availability; water quality degradation; air quality degradation; reclamation and spent shale disposal; and community impacts.

Jan 1, 1981