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By Theodore M. Gurr, James J. Bartels

Phosphate produced fertilizers provide the phosphorous nutrients required by plant life to sustain significant growth, thus improving the production of food for the world's population. Phosphorous replenishment of soil currently can be obtained efficiently by no other means than by direct application of phosphate fertilizer to the soil. Phosphate products are also utilized in animal feeds, detergent, and various industrial processes. Thirty-three countries are presently mining phosphate rock for the production of fertilizers, and its process byproducts. The major phosphate rock producers are the United States, the former Soviet Union, Morocco, and China [(Table 1)]. Phosphate rock is generally defined as a rock material that contains phosphate minerals which are sufficient for commercial usage. Phosphate minerals are found in sedimentary igneous and metamorphic rocks. Economic resources of phosphates are primarily developed from sedimentary rock sources. The apatite mineral family comprises the majority of phosphate constituents from both sedimentary and igneous rocks. Igneous phosphate rocks are generally composed of fluroapatite whereas sedimentary rocks are generally composed of carbonate fluroapatite, or chlorapatite. Phosphate rock is mined by a multitude of processes, including surface and underground mining. The mined rock requires mechanical and chemical processing to liberate the phosphate for utilization as fertilizer. Approximately 85% of the world's phosphate production uses sulfuric acid, with the remaining processes utilizing nitric and phosphoric acids. Ammonia is also introduced in the manufacture of liquid fertilizer, ammonium phosphate and ammonium polyphosphate. GEOLOGY Mineralogy and Chemical Properties Phosphate most commonly is derived from the mineral apatite, which is chemically described as CA5(F,Cl,OH)(PO4)3. Apatite is also broken up into the composite apatite minerals which are fluroapatite Ca5F(PO4)3, chlorapatite Ca5Cl (PO4)3 and hydroxyl-apatite Ca5(OH)(PO4)3. Carbonate CO3 can substitute for PO, forming carbonate apatite, called francolite. The guano phosphate (bird excrement) mineralogy commonly occurs as brushite CaHP04.2H20, monetite CaHPO4, whitlockite Ca3(PO4), and dahlite Ca10(PO4)6(OH)2. Apatite minerals form from igneous sources where they are developed deep in the earth's crust; and the cooling processes are slow, producing long, hexagonal prismatic to tabular crystals. The termination of the crystal can be basal plans or pyramids. In some instances, the crystals are bipyramids. Faster cooling, or sedimentary derived apatites are more commonly cryptocrystalline. Collophane is a name given to cryptocrystalline apatite found in phosphate rock in fossil form. Apatite minerals are relatively soft and are used to describe the 5 hardness on the Mohs scale. Cleavage is poor and develops along the C(0001). The color of apatite minerals varies from colorless, to violet, and blue, but are predominantly green or brown; luster is vitreous to subresinous. Collophane's physical appearance is often opaline, dense, with colloform structure and sometimes concretionary, nodular or pulverulent. Phosphate Bearing Materials Origins Phosphate deposits of igneous and metamorphic origins have been well defined. Sedimentary origins have been defined, but with a greater degree of uncertainty. Research in the 1980s proved out some of these processes through studies of real time deposition in Chile, Peru, and Australia. Igneous intrusive alkali rock and associated contact metamorphic rocks, provide approximately 20% of the world's phosphate. Fluorine containing apatite minerals are the most common materials containing phosphorous. Fluorapatite occurs in most igneous rocks. Fluorapatite and fluorine hydroxylapatite, together with carbonate varieties of these, are important members of the group. Where an essentially pure chlorapatite, carbonate apatite, and hydroxylapatite are rare and restricted in occurrence, the fluorine containing types occur in most all igneous rocks as early formed accessory mineral, usually in microscopic crystals, and may occur as extremely large bodies as magmatic segregations from alkalic igneous rocks. Apatite is also found crystallized in pegmatitic faces of both acidic and basic types of igneous rocks. More specifically, apatite is associated with magnetite deposits, in hydrothermal veins, especially those formed at relatively high temperatures, and in veins of the Alpine type. Apatite is common in both regionally and contact metamorphosed rocks, especially in the crystalline limestones where it is associated with sphene, zircon, pyroxine amphibole, spinel vesuvianite, phlogopite, talc, chloride schists, and as a contact metamorphic mineral.

Jan 1, 1994

By M. A. Berdine, C. N. Thompson, D. Brock

The raise bore method of shaft construction has been success-fully used in the mining and construction industries for over thirty years. In the mid 1990’s, Twentymile Coal Company (“TCC”), now affiliated with RAG American Coal Company, used this method for a moderately deep small diameter shaft and the raise bore and slash method for a shallow larger diameter shaft. In late 2001, TCC contracted to raise bore a 431-meter deep, 6.2-meter diameter shaft. During the raise bore and shaft lining processes, regional horizontal stress fields resulted in extensive elliptical caving beyond the original design diameter. This paper discusses the engineering approaches and procedures used to safely complete construction of the raise bore shaft.

Jan 1, 2004

By W. A. Hustrulid

Introduction A problem that has faced mining engineers and mining geologists for many years is how to best explore a particular prospect so that the basic decision as to whether the material present is ore or only high-grade rock can be made with some confidence. It is obvious that one could not begin a large scale mining program on the basis of tests made on a few hand samples. On the other hand, one could not be 100 percent certain as to the average grade or tonnage before beginning development, as this would require the orebody to be mined out in the sampling process. The basic objectives of the exploration program can be stated as (1) to reduce mining risk; (2) to lessen the cost of development; and (3) to increase the profits of mining. The exploration program should be terminated when these objectives are no longer being met. The construction of tunnels is a specific mining operation. In the exploration program one should gather the data needed to determine (1) the type of excavation technique(s) to be used; and (2) the rate of advance that might be expected. As in the evaluation of an orebody, with the data collected it should be possible to estimate mining costs and project life. Unfortunately, at the present time, it is not possible to do this at least when dealing with medium to hard rock types. The reason for this, it is felt, is basically the inability to identify what specific rock mass properties are of use in tunnel design and to specify how these may be obtained in an exploration program. In short, the exploration program should be designed to give information regarding both the volume (length) and 'grade' (in

Jan 1, 1997

By Kathleen Y. Knoebel

This paper describes a graphical mini computer system called MPASS 2 (Mine Performance Analysis/Simulation) which has been designed to conduct analysis of underground room-and-pillar mining operations using both conventional and continuous mining methods. Dynamic, graphic displays of mine face machine activities are presented on the CRT screen to provide extensive visibility into underground mining activities. MPASS 2 consists of: an interactive inputting system that graphically creates a room-and-pillar mine and describes the mine when production is initiated; a time-step simulator that produces statistical summaries of shift activities and uses CRT screen graphics for accelerated-time display of machine activities and delays; a statistical analysis subsystem for analyzing mine performance data; an industrial engineering system that permits users to enter actual machine activity statistics and replay mine operations on the CRT screen; and a data management system to store historical performance information on mine characteristics and operations. MPASS 2 operates on a Hewlett-Packard 9845B mini computer with 450 K bytes of extended memory, and is written in H-P BASIC. It has been installed at Freeman-United Coal Mining Company in West Frankfort, Illinois and at the U. S. Department of Energy Pittsburgh Mining Technology Center. Applications include production system simulation, industrial engineering analysis, production scheduling, new equipment evaluations, and training.

Jan 1, 1982

By H. Suharyono, R. Hogg

A laboratory investigation was performed on flocculation following the addition of polymer to slurries flowing through pipes and in-line (static) mixers. Results are presented showing the effects of flow velocity, pipe length, in-line mixer elements and the use of multiple addition points. Flocculation performance was measured by the settling rate and the supernatant turbidity. The effects of agitation and mixing time are shown to be generally consistent with the results of equivalent tests (both batch and continuous) conducted in stirred tanks.

Jan 1, 1997

The Chinese city of Shanghai is one of the fastest growing in the world. To keep up with the growth, two tunnels, three-lanes each, are being built beneath the Yangtze River to connect Shanghai with the Changxing River Island. To complete such a large project, Herrenknecht Tunneling Systems was brought in to construct the largest tunnel boring machine (TBM) in the world. The first Herrenknecht S-317 Mixshield has a diameter of 15.43 m (50.62 ft). It was built to construct one of the two 7.2-km (4.5-mile) tunnels. The tunnels are part of the Changjiang Under River Tunnel Project and will be at depths of up to 65 m (213 ft) beneath the Yangtze River in Shanghai-Pudong. These two tunnels are to be opened to traffic in April 2010, in time for Shanghai to host the World Expo. More than 20 million people live in the Shanghai area. The area itself has been growing at an extremely rapid pace for more than a decade and is in need of more space. The search extended beyond the natural limits of the Yangtze River Delta. As part of its incredible growth, 500 new vehicles are registered every day. The new tunnels will connect the Changxing River Island, with a population of approximately 600,000 people to the road traffic network. A bridge construction will also provide a traffic link between Changxing Island and the large island of Chongming.

Jan 1, 2007

By J. Herhold, S. Plaum

"Current and future operational processes in the mining and underground construction sector are under the influence of the prevalent competition and the acute necessity of optimization approaches concerning corporate and project processes. Besides general construction procedures, especially underground construction procedures and procedures in the field of deep shaft construction are high-profile. Those processes describe high technical challenges as well as increased requirements to occupational safety and health. Therefor an occupational safety management, which should be adjustable to the company itself and adaptable to all kinds of projects, shall be created. The creation of such an occupational safety management would lead to an economically optimized and safe (within the scope of OSH law) implementation of internal activities for the performance of construction services underground and in the field of deep shaft construction. With this approach the satisfaction of the high safety request as well as the demand for process optimization, as part of keeping the own competitiveness, will be satisfied successfully at once. PROJECT BACKGROUND Introduction The health and safety protection as well as occupational safety look back on a long historical development, which had brought more important sectors and developments during the last years, not only in Germany but also on the European and international level. The accident insurance protected by law has already been reported in 1884, which is astonishing early. The launch time point is strongly connected with the on-going economic development in the end of the 18th century, but above all this increased in the 19th century. The progress of occupational safety and especially the interest in the integration and the concentrated consideration of occupational safety and the health and safety protection in the company process is strongly visible during the 19th century and directly connected to the industrial revolution. [9] The industrial revolution and with that the development of work places lead to changing demands in the field occupational safety and health and safety protection. Insufficient security precautions caused problems in the industrial revolution, such as personnel and material losses as well as serious injuries and their consequences. These and the fundamental economic endeavours of the entrepreneurs lead therefore to the important step to develop an occupational safety system. [9] The prevailing basic ideas seize the insufficient security precaution of work places as well as the economical and profitable ideas of the entrepreneurs and bring them together. From this the necessary entrepreneur’s task comes into being and that is bringing the work conditions to the way that life and health of employees are not in danger. [9]"

Jan 1, 2017

By G. J. Jansen

Introduction Coal petrography is the microscopic study and description of coal and other organic substances in terms of the microscopically recognizable organic constituents and of the rank of the material. Petrography studies of coal and other organic substances are useful in themselves, and have a number of practical applications. Some of these include determining coking quality of coal, estimating yields of methane from coal beds, and assisting in coal preparation. Petrography studies can also help in mine planning, in source rock studies, in combustion problems, and in synthetic fuel applications. Most recently, petrography has been found to be useful in studying sediment-hosted ore deposits. Microscopic constituents-macerals Under the microscope, coal is a heterogeneous assemblage of the coalified remains of woody matter and plant remains from the swamp or bog from which the coal was formed. The individually recognizable materials making up the organic mass are termed macerals by petrographers. They are the organic equivalent of the minerals that make up rocks. Coal petrographers can examine coal in two ways. Those interested primarily in the microscopically transparent macerals or in the study of very low rank materials, lignites for examples, like to use transmitted light microscopy where light passes through a microsection about 3 to 6 µm (0.0001 to 0.0002 in.) thick (Fig. 1). The dominant red color of the section in Fig. 1 is inherent, not a stain or produced by a filter. Distinct suggestions of textures in the reddish constituents can be seen. The red material is vitrinite and is thought to be the coalified remains of woody tissues. The yellow, lenticular substance is exinite. It is what remains of the waxy coating on a spore. Also seen are white dots of mineral matter and black opaque material that is better seen and described in polished sections. A polished microsection is prepared by grinding and polishing to a mirror polish a compact of coal and embedding resin or a coherent chunk of coal. The resulting microsection is then examined in a reflecting microscope. High magnification, 200X to 400X, and an oil immersion lens are needed to resolve fully the macerals of the organic matter so prepared. Figure 2 shows two macerals, an even gray vitrinite, unstructured and fusinite, a whitish, more or less cellular constituent. Fusinite is thought to represent more or less completely carbonized cellular material. Coal petrographers appreciate that coal is a heterogeneous material. Figure 3 is a view of another section. The generally structureless gray material is vitrinite. The bean-shaped dark constituents are exinites. The long, narrow, somewhat scalloped dark constituent is cutinite. Cutinite is thought to be derived from leaf coatings. Some coal petrographers would describe the large white, structureless mass as micrinite. Others might prefer the term macrinite. A few fragments of fusinite can also be seen. Figure 4 shows a coalified fungal remain, termed sclerotinite. It is surrounded by vitrinite and crushed fragments of fusinite all floating in a sea of embedding resin. Sometimes the microscope reveals the great heterogeneity of coal even on the microscope scale. Figure 5 shows a section with semi-fusinite, inertodetritinite, vitrinite, and micrinite. The nature of the heterogeneity may be judged by noting that the long dimension of the photomicrograph is about 70 µm (0.0027 in.). Measurement of rank Hoffmann and Jenkner (1932) discovered that measuring the reflectance of the vitrinite constituent of coal in a polished section gave a good measurement of the rank of the coal. In practice, a photomultiplier is used to mea-

Jan 9, 1987

By J. C. Harrison

When Exploraciones Eldorado, S.A. de C.V. finished their first phase of reverse circulation drilling at their La Trinidad property in Sinaloa, Mexico they began immediately with permitting and engineering activities. The first phase of drilling lasted four months and ended in April, 1994. The second phase of drilling ran from May through September of 1994. From May through December, 1994, Exploraciones Eldorado performed the permitting and engineering work for their La Trinidad heap leach mine. The mining permit was submitted to the regulatory agencies in February of 1995 and the first draft of the feasibility study finished one month later. The report outlines the permitting and engineering activities that took place during the second half of 1994.

Jan 1, 1996

By Richard R. Klimpel

INTRODUCTION The purpose of this paper is to summarize the current status of reagents used in the mineral industry plus present some current challenges and possible new technologies of the future. Table 1 lists the important families of reagents which, when taken together, constitute at least 95% of the current commercial reagent market. A very approximate estimate of the free world reagent market size in mineral applications is about 1.5 to 2.0 billion dollars (U.S.) using 1985 data. Obviously, to serve such a large market requires the effort of many different types of commercial supply sources. It is estimated that there are over 300 industrial firms in the free world that have a dedicated business/technical structure for supplying reagents related to the mining industry. There are a number of characteristics which are associated with the product families listed in Table 1. Understanding these characteristics helps to provide a realistic economic/technical basis for outlining future challenges in mining chemicals. 1.Essentially all of the products listed are old chemistry in the sense that the molecules have been known and manufactured for at least 25 years. This has not been a highly dynamic field of endeavor from the viewpoint of new product introduction. 2. The greater majority of the products listed can be viewed in commercial terms as "commodity" chemicals, that is, they are available from many sources and the pricing of a some- what generic product generally dominates differences in product quality or uniqueness. With commodity pricing, reagent suppliers significantly reduce research expenditures, loosen product quality somewhat if the applications of the reagents allow, etc. in order to be cost competitive.

Jan 1, 1989

By D. D. Harbuck

Previous studies at the US Bureau of Mines (USBM) have shown that only 70% to 80% of the germanium in domestic zinc process residues can be extracted during H2S04 leaching. To increase germanium extraction, the USBM developed and researched the hypothesis that minor amounts of germanium and zinc silicate, present in zinc calcine, dissolve during the leaching stages of zinc processing, forming soluble germanium and silica gel. This silica gel then selectively adsorbs germanium from solution, rendering the germanium insoluble. Testing showed that as the amount of formed silica gel increased, the amount of insoluble germanium in the zinc residue increased. Several processing alternatives are presented for overcoming this problem.

Jan 1, 1994

By Peter W. Harben, Edward M. Dickson

The distribution of metallurgical grade bauxite deposits will be discussed with the aid of a comprehensive table and a reference map. Information will include operating companies, mine locations, ore grade, and chemical analysis, geological environment, and production capacities. General comments will be made on the distribution of production and its relationship with major consuming regions. The pattern for the future will be assessed, including potential new producers, changing specifications and industry structure.

Jan 1, 1984

By R. K. Mehta, S. K. Dhar, R. R. Mallepali

Introduction The incentives for developing a distributed form of the comminution model include: • for describing the heterogeneous comminution behavior of multiphase mineral systems (i.e. realistic ore bodies, such as complex sulfide ores consisting of chalcopyrite, galena, sphalerite, pyrite and siliceous minerals) and •for generating, for various locked and free particles, in situ, microscopic, breakage behavior such as the mode of fracture (intergranular vs. transgranular), the relative rates of breakage and the breakage distribution. However, the computational difficulty and the effort made in estimating a large number of parameters (Andrews and Mika, 1975; Wiegel, 1976; Herbst et al., 1985, 1988) do not justify the utility of this approach. Also, obtaining the results experimentally is very tedious and time consuming if using this approach. Although recent work in this area (Choi, Adel and Yoon, 1987; Mehta, Adel and Yoon, 1989, 1990) showed good results for liberated particles, the quality of the estimation and prediction was poor for locked particles. Attributing this to the complex breakage behavior of locked particles, it was concluded that additional constraints, and possibly modification in the breakage distribution functional form for locked particles, were necessary. However, further mathematical analysis revealed that the method previously used was in error. The purpose of this technical note is to present the correct solution methodology used in solving the general model equations of a multicomponent mineral system containing multiple classes of locked particles. Previous work and connection The general form of the comprehensive, distributed-component comminution model has been described as (Herbst et al., 1985) [d (m (0) -[ I - B ] S_ m(t) = A m(t) (1)] where [A] is the fundamental matrix/state companion matrix, commonly referred to, in the comminution literature, as the "mill matrix." Note that for a distributed-component comminution model, this is a full, general, real matrix, unlike a lower triangular matrix for a simple grinding model or a lumped-binary grinding model with one locked-particle class (Herbst et al., 1985, 1988). Also note that all of the underlined letters refer to matrices. Herbst et al. addressed the difficulty in arriving at a closed form of the analytical solution of Eq. (1) via similarity transformation [IT J inv (T)]]. This difficulty occurs for several reasons: •[A], as a general real matrix, may have complex eigenvalues and complex eigenvectors. •More importantly, there is no guarantee that a set of eigenvectors of [A] will turn out to be independent. An attempt was made to solve this problem by implementing a decomposition method. With this technique, the mill matrix was decomposed into a sum of lower and upper triangular matrices [(i.e., A = L + U)]. Then the solution was obtained using similarity transformation (Mehta, Adel and Yoon, 1989, 1990). [e(At) = e(L+U)t = e(Lt).e(Ut) _ [ TL Jt- (t) inv(T_L)] [-Tu Ju (t) inv(Tu)]] [But, unfortunately, e 1+U = e t . eu is true only for scalars and not for matrices (i.e., eL+u# eL- eU) unless they commute. In other words. eAt = e(L+u)t= ekt - eU' if LU = UL. Hence, this decomposition scheme must be replaced by a mathematically acceptable method known as the "splitting method"]

Jan 1, 1994

By G. Hilson

The exact application of sustainable development in the mining and minerals industry has precipitated considerable debate in recent years. Since the publication of the Brundtland Commission?s Report, Our Common Future, numerous attempts have been made to define sustainable development in the mining context. The inability of the Brundtland Report to outline an effective sustainability framework, combined with its contention that no single blueprint for sustainable development exists, has prompted many academics and practitioners to provide viewpoints on the application of sustainable development in the mining and minerals industry. This paper provides an overview of the many groups of assessments made of sustainable development in the mining industry. Sustainability assessment and reporting for this industry sector using indicators are also addressed.

Jan 1, 2003

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

GENERAL STATEMENT The primary objectives of any field data gath¬ering effort should be to (1) identify and gather the data necessary for the project and (2) obtain the data in a state-of-the-art manner. All too often the initial field data are collected both areally and tem¬porally in an illogical manner without the guidance of a conceptual model of the ground water flow systems involved or even a review of existing geo¬logic literature on the area of interest. The initial data collected frequently are of limited value while necessary basic reconnaissance information is miss¬ing. Initial field data should be collected with the intent of developing a hydrologic overview of the potential mine site and surrounding area. Ob¬viously, one of the initial objectives is to define the area requiring a hydrologic investigation. The data requirements should be identified by the time frame in which collection should be made and by the corresponding increase in sophistication of the data requirements with development and operation of the mine. The data requirements are summarized in Table 1. INITIAL LEVEL SITE INVESTIGATION Area Determination The initial task of any hydrogeologic investi¬gation is to determine the boundaries of the area requiring study. Obviously, the site of the proposed mine is included in the study area. The areal extent beyond the site may be determined from an eval¬uation of existing geologic and topographic maps. Those formations that overlie the ore body, the formations containing the ore body, and the formation(s) that lies immediately beneath the ore body are of direct concern for proper site recon¬naissance. Additional formations below the ore body may require study depending upon their thick¬ness, hydraulic conductivity, and degree of inter¬connection with the mine workings. This initial viewpoint identifies hydrostratigraphic units based strictly on geologic concepts such as mineralogy and structure. Formation outcrops, synclines, an¬ticlines, faults, and fracture and joint patterns are used to delineate the area of the site reconnaissance. The simplistic hydrogeologic environment (il¬lustrated in Fig. 3, chapter 2) requires that field data be collected via test wells and/or geophysical techniques. This approach is necessitated by the lack of surface features such as formation outcrops, streams, and springs. Fig. 5 (chapter 2) illustrates a slightly more complex hydrogeologic regime. The potential mine sites at locations A, B, C, D, and E each intercept a different ground water flow sys¬tem or combination of flow systems. Therefore, each mine location requires that a different area and size of area be investigated. A more complex geologic setting as illustrated in Figs. 6 and 7 (chapter 2) may be approached differently. The area included for the site recon¬naissance should encompass sufficient surrounding area to include the outcrops of those formations suspected of being influenced by the future mine. Even adjacent areas not suspected of being influ¬enced may be investigated if the formations of in¬terest crop out in those areas. Such an extension of the area of investigation would provide a greater regional understanding of the hydrogeologic properties of the formations (hydrostratigraphic units) of interest. Geologic Investigation The initial step before conducting the site re¬connaissance is to review all existing literature on the geology of the area. Existing information should be augmented with new exploration data on the dip, strike, thickness, and lateral extent of the for¬mations in the area. Exploration hole logs should be reviewed for indications of lost circulation, rub¬ble zones, and water producing zones. Existing aer¬ial photos such as those available from the US Department of the Interior, EROS Data Center,

Jan 1, 1986

By Luciano Ramos, Daniel Santos

Igarape Bahia Mine, which is currently the largest gold producer in Brazil, belongs to Companhia Vale do Rio Doce - CVRD and is situated 250 miles south of Belem, state of Para, Brazil. It came into operation in 1992 with the startup of the CIP plant, fed with high grade ore, presently at 3.4gAu/t. The ore is totally oxidized, containing extremely fine particles of free gold. The ore is soft and low cyanide consumer, with a maximum work index of 12kwh/sht. In 1993 a Heap Leaching Plant was set into operation, handling low grade ore of · 1.s g Ault. The Heap Leaching Plant has undergone two major expansions. In 1994 its capacity was raised from lMtpy to 2,2Mtpy and in 1998, with a thorough remodeling of crushing operations, it was raised again to 3.5Mtpy. The CIP plant, which was originally designed with a capacity for l. lMtpy of ore, was expanded to a 2.2Mtpy capacity in 1994. Presently, the CIP plant accounts for most of Igarape Bahia's total gold output, with approximately 220,000oz per year. Igarape Bahia's annual output is around 360.000 oz. Over the last three years, work has been intensified to improve performance of both processes, aiming at maximizing productivity of the two industrial plants. Reduced costs and increased revenues have been given a special emphasis in the unified improvement program. Cost · reduction has involved developing methodologies to rationalize consumption of materials and inputs, while increased productivity has been given top priority as a means of generating increasing revenues. Thus, all of the improvement and development efforts have had a common goal: to increase operating income.

Jan 1, 2000

By J. W. Mahar, E. J. Cording

INTRODUCTION In exploration for rock tunnels, the geology should not only be described, but its effect on excavation and support assessed. It is not an easy task to correlate exploration results with support and excavation requirements, even when the exploration program is detailed and geologic conditions are relatively well known. Many of the significant geologic features are subtle and their effect is difficult to interpret from exploration results. However, in similar geologic settings, there are specific geologic features which will cause recurring support problems. Such features should be actively sought out when exploring in a given geologic setting. In blocky and seamy rock, the primary features controlling performance are the joints, shears, and shear zones. This paper describes the effect of such features on the formation and movement of rock wedges in tunnels driven in foliated metamorphic rocks in Washington, D. C. and New York City. In both areas the foliation commonly forms a N-S striking plane of weakness along which major shear zones, shears, and joints have formed. In addition, the structural history of the two areas has been similar, so that there are similarities in the orientation and character of the other major joint sets and shear zones in the rock mass. The observations were made in tunnels ranging from 10 to 70 ft in width and excavated at depths ranging from 80 to 800 ft. Most of the tunnels described were deep enough to be located in unweathered rock, or in rock only slightly weathered along joints and shears. Variations in the planarity, filling, spacing, and attitude of joints, shears, and shear zones accounted for significant differences in the

Jan 1, 1974

By Arun Patel, Diane Hirsch, Pamela Moran

The Metropolitan Washington Airports Authority (Authority) has undertaken a tremendous expansion of Washington Dulles International Airport in Fairfax, Virginia, including upgrading passenger transportation between concourses. The first stage of this expansion envisioned a shallow cut-and-cover pedestrian tunnel between the Main Terminal and Concourse B with associated vertical circulation structures. At the beginning of the design contract, the Authority’s consulting team of Earth Tech, formerly Kaiser Engineers, and the Dr. G. Sauer Corporation compared the cost and disruption of constructing the tunnel as a cut-and-cover structure to mining the tunnel using the New Austrian Tunneling Method (NATM). Upon review, the Authority endorsed the latter method.

Jan 1, 2003

By John M. Ackerman

INTRODUCTION In the spring of 1988 the Joint Venture of Freeport-McMoran Resource Partners, Limited Partnership, IMC Fertilizer Inc, and Homestake Mining Co. was awarded the sulphur lease for Main Pass Block 299, lease number OCS-G 9372. This was one of eleven leases awarded to the Joint Venturers. Following the initial discovery wells in December 1988, a program of delineation drilling confirmed proven sulphur reserves of 67 million long tons. Proven, recoverable oil and gas reserves are 39.4 million barrels and 7.2 billion cubic feet, respectively. Development of the sulphur mine was given approval as a fast-track project by the Joint Venturers in 1989. The oil and gas reserves were acquired from the original hydrocarbon lessee in 1990 and given fast- track status immediately. Fast-track for these projects meant design and engineering would not be complete before construction began JOINT VENTURE The Main Pass Joint Venture is one of thirteen joint ventures formed between Freeport and three other companies - IMC Fertilizer, Inc., Felmont Oil Corporation, a wholly owned subsidiary of Homestake Mining Co., and Texasgulf Minerals and Metals Co. Felmont has subsequently changed its name to Homestake Sulphur Co. and Texasgulf assigned their interests in the three leases they participated in to their parent company. Texasgulf did not participate in the Main Pass 299 joint venture. Joint venture negotiations, anticipating a lease sale in mid-1988, began in December of 1987. This Joint Venture was the first of its kind; created to acquire offshore leases, explore, develop and mine sulphur. The Minerals Management Service announced a lease sale date of February 24, 1988 on the first business day of 1988. This greatly accelerated the joint venture negotiations. Of the thirteen leases the Joint Ventures bid on, eleven were awarded. Freeport holds its interest in all the leases through its ownership interest in Freeport-McMoRan Resource Partners, Limited Partnership, and Resource Partners is the operator on all of the leases. The Main Pass joint venture percentage ownership is: 58.33 Freeport-McMoRan Resource Partners 25.00 IMC Fertilizer, Inc. 16.67 Homestake Sulphur Co. 100.00 The Main Pass Joint Venture paid $3,401,757 for the Main Pass lease and will pay a royalty of 12.5 percent of production value to the MMS . LOCATION The Main Pass mine complex is located in the Gulf of Mexico, in U. S. federal waters, about 27 kilometers (17 miles) east of Venice, Louisiana or 140 kilometers south east of New Orleans, Louisiana. It is situated in about 63 meters (210 feet) of water. HISTORY The Minerals Management Service (MMS) of the United States Department of the Interior administers the mineral properties of the United States located in federal waters. Periodically the MMS holds lease sales of blocks under its jurisdiction. Prior to the offshore discoveries of sulphur associated with salt domes leased for hydrocarbons, the MMS leased blocks with all minerals including hydrocarbons awarded to the successful bidder for the block. In 1963 MMS held the first lease sale of blocks specifically for sulphur. This sale was followed by a similar sale in

Jan 1, 1992

By J. Sulaiman Lubis

Indonesia is a developing country in Southeast Asia with a population of some 180 million people. It has a stable political environment and currently enjoys high rates of economic growth. Indonesia has abundant reserves of natural resources, ample for its own needs and for export. Energy resources include oil, gas and coal. The oil and gas industries are well established domestically and for export. In the last few years, though, coal industry development has been rapid. Coal resources from bituminous to lignite amount to more than 30 Gt (33 billion st). That is more than enough to meet domestic needs and provide significant amounts for export. Figure 1 shows coal basins in Indonesia. Coals in Indonesia are generally young steaming coals. They are very low ash and sulfur, high volatile, bituminous B and C. The Indonesian government's state coal company is called Perum Tambang Batubara. The company has actively promoted the development of its coal for domestic and export markets. In particular, the government has placed priority on non-oil exports of which coal is a major element. The government strives to honor all contractural commitments for the export of Indonesian coal from contractor, private and government mines. From 1987 through 1989, coal production has increased from about 3 Mt (3.3 million st) to 9 Mt (9.9 million st). Exports have grown from I Mt (1.1 million st) to 3 Mt (3.3 million st). These are significant increases for a small industry with limited infrastructure. But with growing investment and development, these production and export levels will increase substantially, and Indonesia will be a significant world supplier of coal in the 1990s.

Jan 1, 1990