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By Russell K. McFarland, Gloria T. Saxton

Introduction The March 1969 issue of Civil Engineering contained on article entitled "BART" Subway Construction: Planning and Costs" authoried by Thomas R. Kuesel. This article describes in some detail the innovations developed in planning and management to undertake the design and construction of the BART Project. This 75 mile long system contained 17 miles of urban tunnels and 13 subsurface stations. Within this article Mr. Kuesel very nicely listed the cost of the 70,000 linearfeet of bored tunnel, 23,380 linearfeet of cut and cover tunnel, and the costs of the thirteen underground stations. Ten years subsequent to the publishing of Mr. Kuesels article, it is very sobering to realize that San Francisco obtained a bargain of a magnitude that we are just beginning to realize. Table 1 is a listing of tunneled line sections taken from the paper. The average cost shown in this figure, including sections constructed under compressed air is $1,620 per foot of tunnel, with bid dates ranging from June 1966 thru October 1968. This average cost translated to about $16 million per double track mile of twin tunnel system.

Jan 1, 1979

By J. Owens

The methodology of quarrying changed significantly in the Indiana Limestone industry in the sixty years between September 11, 1941, the date of the Pentagon groundbreaking ceremony and September 11, 2001 when the building was damaged by American Airlines Flight 77. So too, though to a lesser degree, did the machinery and methods used to fabricate the stone. The rededication ceremony on September 11, 2002 marked the end of the Phoenix Project, as the rebuilding effort was named. The story of this remarkable project illustrates what the American construction (and Indiana Limestone) industry can accomplish when working toward a common goal.

Jan 1, 2004

By William R. Nash

Introduction As ore grades decline and deposit depths increase, problems and costs of mining construction increase rapidly. Ground water greatly impacts the cost of mining construction. In developing or exploiting ore bodies or coal mines, stored ground water in waterbearing formations is often encountered. Man-made conduits or shafts are constructed, as are raise bores for ventilation (up to 6-m-diam or 20-ft-diam), or smaller diameter drill holes, used for either power cables or rock dust. In underground construction and mining, it is possible to inherit unmapped and abandoned drill holes either from oil or gas exploration, or from previous geological investigations. There also exists within underground work exposure to faults, fissures, and jointing. A mine development may encounter unknown aquifers or, unluckily, have an ore body that is an aquifer. Water may invade an existing underground structure, due to concrete deterioration or to damage that may occur to an existing shaft or tunnel concrete lining. An underground development may intersect a drill hole that was not properly grouted when abandoned. It subsequently formed a conduit or an active path to conduct water into the mine. Water inflow may range from insignificant to a magnitude sufficient to inundate an area or an entire underground development. Corrosion imposes major costs. In shafts, it can cause accelerated wear and deterioration, and subsequent early replacement of hoisting ropes. It can also cause deterioration, misalignment, and subsequent accelerated wear and replacement of timber and steel guides and buntons. Utility maintenance (power cables, air, water, and ventilation lines) also can become a problem. Corrosion imposes major costs. Skips and skiploaders provide a never-ending series of maintenance headaches when exposed to an ingress of water. Numerous problems are found in declines with invert and rail maintenance and with partitions in over-under coal mine slopes. Ground water interacting with an underground ventilation system can result in: • Increased ventilation resistance due to roof falls and the spalling of ribs caused by ice heaving. • Restriction in shaft or slope cross-sectional area due to ice buildup during winter months. This may be a safety hazard to access as well. • An increase in the moisture content entering the ventilation air that condenses underground and causes electrical and equipment maintenance problems. Underground structures also incur water-caused problems. The concrete lining in shafts, slopes, and tunnels may be subject to: • Active mine waters causing concrete and reinforcing steel to deteriorate - perhaps to the point of collapse. • Load redistribution around a concrete lining, caused by soil dislocation due to water movement. The resulting stress may be in excess of the calculated design loading. Backwall injection with grout of the completed concrete lining may solve these water inflow problems through low-pressure injections of cement and chemicals. This fills voids at the interface of the concrete lining with either the soil or rock excavation. Surface structures may be jeopardized by lowering the ground water table, resulting in surface settlements. Surface settlements can occur in buildings, headframes, hoist foundations, mills, conveyor structures, or in rail haulage. Areas of differential settlement can lead to derailments, improper wear of hoisting ropes on sheaves in headframes, and the misalignment of bearings and brakes. Mud jacking and compaction grouting may remedy these problems. To reduce operating costs, increase efficiency, and increase safety, inflow water to the mine should be minimized. For an operating mine with a water problem, a water inflow survey should be taken. Quantities of water flow should be examined at all accesses (shafts, slopes, bore holes, and raise bores) at the faces, haulages (rails or conveyors), and sump discharge. From this examination and quantity survey before and after heavy rainfalls, valuable data for elim-

Jan 3, 1984

By Richard S. Mateer

The percent ash in a coal blend is equal to the weighted average of the ash contents of the component coals. If the raw coals differ in washability characteristics, the total yield may be maximized by washing the component coals to different quality levels. A mathematical basis for blend maximization is developed and a computer program is described The program determines the component weights that maximize the yield, while meeting an individual coal-quality specification. The procedure is directly applicable to linear parameters of grade quality such as percent ash, percent sulfur and the calorific value. A transformation of variables permits program execution to meet a sulfur-compliance specification. Blends may consist of any number of component coals.

Jan 1, 1997

Rest potential, cyclic voltammetry and chronoamperometry measurements were made to study the effects of cathodic polarization of chalcopyrite simulating the mineral contacted with grinding media under a nitrogen atmosphere. The reaction products on the chalcopyrite surface were identified by XPS and the mechanism of the cathodic reaction was proposed. Micro-flotation tests were performed to investigate the effects of surface changes on the floatability of chalcopyrite.

Jan 1, 1991

By G. Mbuyi Kamba

Literature is rather abundant on the topic of steady-state network analysis programs. Many versions exist, some of them have real extended facilities such as full graphical manipulation, fire simulation in motion, etc. These programs are certainly of great help to any ventilation planning and often assist the ventilation engineer in his operational decision making. However, what ever the efficiency of the calculation algorithms might be, their weak point still is the overall validity of the model. This numerical model, apart from maybe the questionable application of some physical laws, depends directly on the quality of the data used to identify its most influencing parameters such as the passive (resistance) or active (fan) characteristic of each of the branches in the network. Considering the non-linear character of the problem and the great number of variables involved, finding the closest numerical model of a real mine ventilation network is without any doubt a very difficult problem. This problem, often referred to as the parameter adjustment problem, is in almost every practical case solved on an experimental and "feeling" basis. Only a few papers put forward a mathematical solution based on a least square approach as the best fit criterion. The aim of this paper is to examine the possibility to apply the well-known simplex method to this problem. The performance of this method and its capability to reach the global optimum which corresponds to the best fit is discussed and compared to that of other methods.

Jan 1, 1995

By Martin F. Grier

The Mt Todd Gold Project is located 300km to the south of Darwin in the Northern Territory of Australia. The identified resource comprises 46 million tonnes at 1. 65g/t using a 1. 0g/t cut-off ( 50 million short tonnes at 0.05oz/st). The resource is open to the north and at depth. Mineralisation comprises easterly dipping sheeted quartz/sulphide veins, typically 10 to 20 millimetres in thickness, hosted by hornsfelled greywackes. The majority of the ore body is primary ore with only 10% classified as oxide ore. Early testwork showed that the ore was not suitable for heap leaching, giving only 50% recovery at a -3mm crush size. Acceptable recoveries were obtained at a P80 of 75 micron. However, the ore is extremely hard.

Jan 1, 1992

By John A. L. Campbell

Are safety concerns justified regarding the potential for a gas explosion due to recirculation when a scrubber is used on a continuous miner? The role of a respirable dust scrubber on a continuous miner section using blowing face ventilation is examined in this paper and the above question answered. Methane control using high efficiency scrubbers coupled with blowing face ventilation is promoted.

Jan 1, 1987

By Archie M. Richardson, Carl E. Brechtel, Tom R. Kelly, Frank Feero

Recent work to upgrade the ventilation system for the el Mochito lead/zinc mine in central Honduras is discussed. Network modeling and underground measurements were used to evaluate cost-effective alternatives for achieving satisfactory ventilation in a complex and expanding underground operation. Both interim and long-term solutions were implemented to make mining possible under difficult conditions. INTRODUCTION Mining operations at the el Mochito Mine, located in the central highlands of Honduras, Central America, have been virtually continuous since the opening of the mine in 1948. Initially a high-grade silver mine, the mine has expanded along a westward trend of pipe-like orebodies to a distance of roughly one mile from two centrally located shafts. Production of the relatively large San Juan orebody at the western most extension of the mine (Paddock, 1981) led to the introduction of diesel-powered equipment; however, the ventilation infrastructure was insufficient to meet the needs of mechanized mining. A succession of owners/operators in the 1980s allowed the existing ventilation infrastructure to decay to the point that ventilation in the production areas of the mine was very poor. Environmental conditions in some working areas were not conducive to efficient ore extraction because of high dry bulb temperature, high humidity, and diesel emissions. Upon acquiring the mine in 1990, Breakwater Resources of Tucson, Arizona began an aggressive program to refurbish the mine infrastructure to complete extraction of the San Juan orebody and to allow the extension of the mine another 2500 ft to the west for extraction of the Nacional orebody. The program included increasing the capacity of the main ventilation system. This article presents a case history of the process of upgrading the ventilation system in a mine where extensive old workings cause large air leakage. This process has been one of selecting solutions to difficult technical problems that are compatible with the existing mine infrastructure and economic constraints. The initial ventilation system is described in the background section, along with ventilation projections for the mine expansion. Field characterization of the ventilation system for design verification and fan specification is then discussed. The paper describes a series of interim changes to the system to improve ventilation pending completion of new ventilation boreholes. In addition, the temperature/ heat problems in the mine are described. BACKGROUND Initial Condition of Ventilation System The ventilation system is illustrated in Figure 1, which shows the extent of mining with the main ventilation paths superimposed. Early mining around the two shafts opened up vertical connections (stopes and raises) over the entire 2420 ft (737.6 m) of vertical extent, and mining progressed to the west primarily using compressed air and electric-powered equipment. Since ventilation was not a complex problem in the original mining system, the stopes and interconnecting raises were not sealed. The San Juan orebody was much larger than the silver ore zones mined previously, being primarily zinc and other base metals. Its geometry, size, and grade allowed the use of vertical crater retreat (VCR) stoping with diesel mucking and haulage equipment. Its depth, along with the existence of warm groundwater, resulted in a mine climate problem on the lower levels. To establish a complete ventilation circuit, two vertical boreholes (Bonanza Nos. 1 and 2) had been drilled by previous owners from the surface in the vicinity of the San Juan orebody. The system design called for air to be drawn down the intake shafts, across the lower mine levels to the San Juan workings, then up through the San Juan ramps and ore passes to these two exhaust boreholes (see Figure 1). In practice, however, only the Bonanza No. 1 borehole was drawing air through the desired path. Leakage across the old upper levels from the intake shafts, the Caliche tunnel, and from intervening abandoned stopes and raises supplied most of the air flowing to the base of the Bonanza No. 2 borehole. In effect, there were two ventilation circuits in semi-parallel through the mine, of which only one was delivering appreciable air to the San Juan workings.

Jan 1, 1993

By Alexander N. Winchell

"The waters of Lake Superior flow into those of Lake Huron through the St. Mary's river. The rapids in this river are about half a mile wide and three-quarters of a mile long, in which distance the fall amounts to about twenty feet. Since this was the only obstacle to navigation between the west end of Lake Superior and ports on any of the other Great Lakes except Ontario, attempts were made many years ago to permit the passage of small boats from Lake Huron to Lake Superior by means of canals and locks. The first canal was built on the Canadian side of the river by the Northwest Fur Company in 1797-98. The lock was 38 feet long, 8 feet 9 inches wide and had a lift of 9 feet. A tow path was made along the shores for oxen to track the bateaux and canoes through the upper part of the rapids., The lock was destroyed during the war of 1812 by United States troops from Mackinac Island.The first ship canal, known as the State Canal, was built on the American side of the river in 1853-55, about 750,000 acres of land in Michigan having been granted by congress to a private company as a 'concession for its construction. This canal was more than a mile long, 65 feet wide at the bottom and 100 feet wide at the water's surface. It had two locks, each 350 feet long by 70 feet wide, with a lift of about 9 feet. The depth of water in the canal was about 13 feet and in the locks about 11 1/2 feet."

Jan 1, 1920

By P. R. ZETTWOOG

HISTORICAL BACKGROUND A program in France to develop personal [a] dosimeters has been initiated 1974. The patent on which is based the present device was obtained in 1972 * . From 1972 to 1974, the possibilities of applying certain ionograph track detectors to the spectrodosimetry of radon daughters was explored. The first prototype were produced in 1974. It took four years (from 1974 to 1978) to produce an autonomous dosimeter whose components has a sufficient life span, especially for the turbine motor unit. Qualification in the laboratory was obtained in 1977. In 1978 it was obtained in the mine for technology (autonomy of 12 hours and a life span of more than one year) and in 1980 for monitoring. 300 dosimeters have been tested in underground mines all together. Indispensable peripheral equipment were also developed from 1976 to 1980 : calibration devices, equipment to prepare and develop the films, read out systems. The concept of an "Integrated System of Individual Dosimetry" (ISID) based on a personal [a] dosimeter measuring exposure to radon daughters, thoron daughters, ore dust and external irradiation doses was proposed at the end of 1980. Since January 1st 1981, ISID is used on a routine basis in some french mines, situated in remote area, and appears to be very competitive with the ambiant dosimetry. The latest version of the dosimeter is produced in mass series since June 1981 and should equip all french mines in 1982. DESCRIPTION OF THE INSTRUMENTATION DEVELOPMENT OF THE DOSIMETER MEASURING HEAD The measuring head is based on the use of ionographic film to detect a tracks. In fact, the measuring head is a spectrodosimeter which measures separately over the period of exposure: - the potential [a] energy inhaled due to the decay of Po 218, Po 214, and Po 212 ; - the number of Rn 222 atoms inhaled ; - the inhaled total [a] activity of the five long-lived emitters present in the ore dust. The contribution to the total inhalable potential [a] energy of these various radionuclidesin a typical underground mine is studied in Appendix I. The measuring head described in detail in Appendix II, is able to satisfy all the implications made in the ICRP recommendations. Appendix III deals with the use of this measuring head in the cases where the equilibrium factor is lower than 0.1. This situation occur in open-pit mines where account must be taken of the Rn 222 contribution, which is no longer negligible in relation to that of its daughters. CURRENT DOSIMETER PERFORMANCES Table I shows the characteristics of the latest dosimeter. Appendix IV should be consulted concerning qualification of the dosimeter in the laboratory and in mines, technological development which finally produced the [a] dosimeter and its peripheral equipment, and technical presentation of the ISID (Integrated System of Individual Dosimetry) based on the concept of a multirisk personal dosimeter. Data on the installation and operating costs of such a dosimeter, which would seem to be competitive, are also given in this Appendix. ADVANTAGES OF PERSONAL DOSIMETRY AS COMPARED TO AREA MONITORING The results of the first eight months of experiments carried out under real conditions in an underground mine site are given in detail in reference 8. Area monitoring : The monthly exposure per worker to inhaled Rn 222 was determined from the knowledge of time spent in various areas of the mine and for the different mining operations, as well as from numerous and systematic sampling of the Rn 222 concentration in all work places. Personal dosimetry : The exposure to potential energy from radon daughters was measured by an [a] dosimeter developed by the CEA and worn by each of the 160 miners during eight months. In this way 160 x 8 pairs of monthly individual exposure values have been obtained which can be statistically studied. This test was decisive for us because it proved that the [a] dosimeter was technically sound (very few defects over one year for 160 dosimeters) and especially that personal monitoring devices were superior to area monitoring devices. The following conclusions can be drawn 1. The exposure distribution obtained by personal dosimetry is log-normal. This is true for the results on the whole as well as for groups of results relating to certain explanatory variables. See fig. la, 1b, 1c. 2. The exposure distribution obtained by area monitoring does not correspond to any type of distribution. If the results of personal monitoring are taken as a reference, area monitoring tends to underestimate the high exposures and overestimate the low exposures.See fig. 2. 3. [a]-energy exposures are underestimated when calculated from radon exposures and the equilibrium factor found in the considered mines. This is due to episodes or to zones of high radon concentrations not registered

Jan 1, 1981

By Sam H. Patterson

Australia has led the world in bauxite production since 1976, and only the Republic of Guinea has larger bauxite resources. India has a small integrated aluminum industry, and deposits containing more than 1 Gt (billion metric tons) of bauxite were discovered in the 1970's. The Peoples Republic of China has large bauxite resources scattered in several regions, but it is a monohydrate type that is difficult to process for aluminum. Indonesia and Malaysia both have long histories of bauxite mining, and both have limited resources of high-grade bauxite. Districts containing bauxite resources in the 10 Mt to 150 Mt (million metric tons) range are scattered in countries along the eastern rim of the Pacific Ocean, on islands in this ocean, and on the western and northern rims of the Indian Ocean.

Jan 1, 1982

By Mike Costello

The gold mines operating within the Newcrest Group, Boddington (20% owned), New Celebration, Ora Banda and Telfer, have accumulated many years of operating experience. Cell designs and operating methods include both steel wool and woven stainless steel and plating practices cover electrowin, electrorefine, normal' recirculation and pass out modes. Besides gold the solutions contain reasonable quantities of silver, copper and nickel.

Jan 1, 1995

By David Williamson

In the post-World War II years, metals analysts and statisticians have tracked the demand for metals in line with changes in Organization of Economic Cooperation and Development (OECD) industrial production (IP) growth rates, Williamson said. This was because the correlation between IP growth and metal demand was reasonable. "However, the correlation was exaggerated," he said. During times of expanding IP growth, metal demand increased at a faster proportional rate than IP growth. This was probably due to industry restocking in anticipation of growing demand at the start of each economic cycle. Conversely, metal demand would slacken at a greater rate than would be suggested by negative IP growth as industry destocked to reduce costs. Nonetheless, he said, a reasonable correlation could be painted between IP growth over the longer term and metal demand. "Yet, although this correlation has stood well since the last world war, it has been based on the fact that the bulk of the world's IP growth stemmed from the industrialized countries of the western world, lately including Japan," Williamson said. The so-called "developing world" had been of little consequence. The Soviet Union and other communist bloc countries were deemed to be closed, self-contained entities that, for each metal, would either be net exporters or importers, he said. These quantities would be used by analysts to calculate the overall supply/demand equation for the western world only and to deduce whether a commodity was in shortage or surplus. It is now believed that this method of projecting total world supply and demand for raw materials is outdated, Williamson said. It does not take into account the worldwide political changes that have occurred since the collapse of communism and the revitalization of China. "It is no longer appropriate to assess global balances for raw materials on the basis of three economic blocs," he said, including the western world, developing world and communist bloc. Rather, global balances need to be projected on a global basis. In this regard, since the collapse of communism and the removal of many other totalitarian regimes, capitalist forces are attempting to satisfy the expectations of the great mass of the world's poorer people, Williamson said. Such people, usually located in Asia, Africa and Latin America, have aspired to the same standard of living as people living in western Europe, North America and Japan. "Now, with free market forces at work, their aspirations will start to be met." Consequently, the demand for metals and other raw materials will now rise at a much faster rate. The production of raw materials has to keep pace with rising IP in the developed world. It will also have to keep pace with the demands associated with the rising expectations of increasing populations in the developing world, as well as from within the old communist bloc countries.

Jan 1, 1997

By J. E. Gebhardt, J. A. Herbst, K. Y. Lee

Benefits of proper control of reagent usage in flotation circuits are typically improved metallurgy and savings in reagent costs. Improved metallurgy can mean more consistent product quality, i.e., final concentrate grade, better recovery of product values from the feed, or higher plant throughput at existing target recovery, and grade values. Flotation performance is sensitive to a variety of process disturbances which occur in operating plants, such as changes in flow rate, percent solids, size distribution. flotability of mineral species, etc. A way to handle these variations is to fully understand the dynamic flotation responses to disturbances and to implement a suitable control strategy to compensate for these disturbances. Depending on the objectives of the control system, various types of control strategies are available which employ different levels of refinement to achieve the desired performance. Typically, variables such as collector and frother dosages and reagent addition points can be manipulated to affect the performance of the circuit. In the case of sulflde mineral flotation, manipulation of the process electrochemical potential, in flotation and in grinding, offers another degree of process control. Because of the complex and interactive nature of flotation process variables, optimized reagent control requires consideration of all, or at least the most important, interactive variables of the flotation circuit. Model- based optimizing control provides a framework to handle the complex and dynamic nature of flotation reagent process control.

Jan 1, 1994

By B. Grosso

The National Italian Regulation concerning environment protection imposes that industrial areas are provided with systems aimed at preventing the circulation of contaminated groundwater. These systems can be static or dynamic and operate basically by intercepting the contaminated flow. Their effectiveness, realization time and costs depend on the intervention type and on the features of the specific site. The selection of the best solution is complex and the results obtained by this selection may be affected by residual risks related to the uncertainty of the hydrogeological and geotechnical characterization of the site. With regard to the industrial area of Portovesme, located in the south of Sardinia, the paper presents the analysis of alternative interventions aimed at the protection of the groundwater. The attention is focused on the evaluation of their effectiveness, impact on environment and, finally, time and costs of construction.

Jan 1, 2008

By B. J. Arnold, C. D. Harrison, R. A. Lohnes

More than 544 Mt (600 million st) of coal are handled annually for use by this country's coal fired power plants. Coal is transported in various ways: overland conveyors, railcars, trucks and barges. It can travel short distances or thousands of miles, picking up moisture, freezing or drying. When the coal is received at the power plant, environmental problems with fugitive dust and further handling problems can arise. To ensure that power plant availability is not jeopardized by coal handling problems, the Electric Power Research Institute's (EPRI) Coal Quality Development Center (CQDC) developed a research program aimed at addressing utility coal handling problems. The program has identified key areas, and is investigating the cost and cause of coal handling problems as well as the solutions to these problems. The ultimate goal of the program is to develop a "handleability index" that utilities can use in their coal specifications or hardware for a utility's sampling system to predict handleability and determine if a coal shipment should be accepted.

Jan 1, 1993

By Joe W. Siefke

The world-class Kramer sodium borate deposit is being developed by modern open pit operations near Boron, California. The deposit is a bedded, lenticular sedimentary sequence of borax and kernite crystals together with claystone. The borates dip south into a structural basin-bounding fault and were formed in the bottom muds of a permanent shallow lake. The lake was fed boron and sodium-rich solutions from a thermal spring source of volcanic origin. In addition to deposit geology, present day geotechnical concerns such as groundwater and slope stability will be discussed.

Jan 1, 1995

By S. Zaharia

The authors present the state-of-the-art regarding natural and anthropic hazards on the stability of the saliferous Costiui basin. The factors that may potentially result in sliding, piping and collapse, are emphasized, given the existence of a large number of old salt mines. Also, a geotechnical risk map of this hydrosalt complex in Romania is presented.

Jan 1, 2008

By Virgil R. Huff, Ihor Havryluk

P. T. Pacific Nikkel Indonesia (PTPNI) was incorporated in Jakarta, Indonesia in February, 1969 by a group of Dutch and North American companies. At the same time, a Contract of Work with the Government of the Republic of Indonesia was signed, granting Pacific Nikkel all the necessary licenses and permits to explore and develop all nonradioactive minerals in two separate areas in Irian Jaya, eastern Indonesia. Nickel mineralization occurrences were confirmed by Dutch geologists in the two areas in 1952 and 1955, however, detailed exploration began in June 1969 after the Contract of Work was signed. Since that time, numerous studies and investigations have been conducted to determine the feasibility of producing metallic nickel in Irian Jaya. Four engineering studies, two bulk sample tests, an oceanographic survey, and a preliminary site investigation indicated that construction and operation of a nominal 100 million pounds per year metallic nickel plant on Gag Island were technically feasible. The fourfold increase in the price of oil in late 1973 without a corresponding adjustment in the price of nickel necessitated a reevaluation of the project, the results of which showed that the project required other conditions to be viable. Subsequently, analysis of: the future projected nickel supply-demand and cost-price relationships, the economics of treating a higher grade feed, and participation by the Government of Indonesia, indicate that the project will be viable. Therefore, planning of the Gag Island Nickel Laterite Project is continuing with the objective of commencing production to supply the market in the 1983-1984 time period.

Jan 1, 1979