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By Ammar Henchiri

INTRODUCTION A current need of the phosphate industry is the development of process technology for treatment of high carbonate content ore. About 75 to 80 percent of the world phosphate reserves (1) are associated with carbonate gangue, which is not amenable to treatment by the existing techniques. Numerous laboratory and pilot plant studies have been devoted to carbonate-phosphate separation. Different techniques were involved (washing, sieving, attrition, flotation, calcination, and leaching). For technical and economical considerations, flotation appears to be an efficient process for this problem. Separation of carbonates (calcite and dolomite) from igneous phosphate is applied in industrial plants in Brazil, Finland, and South Africa. But, for sedimentary phosphate, no industrial realization exists at this time, with the possible exception of some plants in China. The main problems with sedimentary phosphates are: • high substitution by CO3-2 and F- for P04 -3 in the apatite lattice. • larger surface area of the phosphate particles because their surface is porous and irregular. • tendency of sedimentary minerals to produce more slimes in conditioning than the crystalline minerals, hence, larger dosages of collectors are required for sedimentary minerals. Investigations reported in the literature indicate that most processes developed for sedimentary carbonate-phosphate separation involved inverse flotation of carbonates using fatty acids as collectors (2), (3) associated with phosphoric acid (4), monosodium phosphate (5), F- (6), or SiF6 -2 (7) as phosphate depressants. Later investigations, conducted by A. Henchiri and G. Baudet (8), (9), (10), (11), (12), (13) in the BRGM technology department, of phosphoric esters revealed that these reagents are selective collectors for carbonate-phosphate separation. The above investigators developed a process which used phosphoric esters to collect carbonate minerals and sulfuric acid or sodium fluorosilicate as depressants for phosphate. Extensive comparative tests for different processes on the same phosphate sample show that the process developed at BRGM is one of the most promising methods proposed for sedimentary phosphate-carbonate separation. It should be pointed out, however, that phosphoric esters make abundant froths. The handling of these excessive froths will be a problem in an industrial-scale plant. This paper outlines test work performed in order to optimize and to improve the efficiency of the flotation process on a sedimentary phosphate ore selected from the Sra Ouertane orebody. The Sra Ouertane flotation process, illustrated on Figure 1, first removes carbonate minerals by inverse flotation and then recovers phosphate as a froth product, leaving quartz as a cell product.

Jan 1, 1993

By Wen-Long Cai, A. Frederick Banfield

This paper investigates, through case studies on a porphyry copper and a coal deposit, the differences and relevances between an approximate production schedule approach, i.e., the best case and the worst case schedules and a practical production schedule approach. The comparisons were with regards to: 1) choosing an optimum ultimate pit size, 2) determining processing capacities, 3) selecting 'optimum' cutoff grades, and 4) blending. The comparison criteria was to maximize the project net present value. Conclusions were drawn based on the study results.

Jan 1, 1996

By Alvin W. Schillinger

Drilling was not entirely satisfactory in the search for native copper in the Osceola amygdaloid footwall as mining showed oreshoots to be more continuous than drilling indicated. The Geophysics Department of Michigan Technological University developed a portable induced polarization drill hole probe with a 3 electrode configuration and a sampling radius of 5'± A 20 ma current of alternately reversed polarity is pulsed at 3.5 sec. intervals and readings are taken every two feet. Potential is read during the "on" cycle for resistivity determinations. During the "off" cycle, after 10 ms delay, the I.P. potential is sampled for 10 ms and recorded. Resistivity (ohm-feet) and "S" values (mv/v) are plotted on semi-log paper. A lithologic log is plotted based on resistivity and anomalous "S" values noted. The low resistivity amygdaloid contains sills of high resistivity basaltic trap. Verified by core logs, amygdaloid-trap contacts could be picked to ±.5' from resistivity alone. Lithologic logs of long steel holes, based' on resistivity, now replaced sludge logging. An "S" value of 30 mv/v was established as the lower limit of diagnostic I.P. effects in mineralized amygdaloid and 50 mv/v as a threshold value for ore. Of 914 footwall zones drilled, 315 were probed yielding 203 anomalies. Success increased from 34% for drilling to 72% for drilling and probing. As checked by mining, 46 probe results were 78% correct. Failures were due to the instrument not detecting copper or to the misinterpretation of an anomaly. No false anomalies were found.

Jan 1, 1964

By Brenda B. Mehnert

Long-term monitoring is necessary to successfully develop predictive subsidence models. Thus, the Illinois Mine Subsidence Research Program (IMSRP) has documented subsidence over a longwall mine in south-central Illinois throughout a 3-year period. No monitoring results of this duration have been previously published for longwall mining in Illinois. To study the effects of surface subsidence and the rate of subsidence, precise level surveying was conducted at the site two or three times a year. Level surveys were conducted at approximately the same time of year using a WILD NA-2 level with a micrometer. Second-Order, Class-I, closure errors were obtained in each survey. Survey monuments were designed to minimize frost-induced movements. At this particular site in southern Illinois, subsidence over chain pillars and the panel centerline continued 3 years after mining. Since mining in 1988, 6.67 feet of subsidence or 70% of the extracted height has been documented over the panel centerline, with almost 0.30 feet in the last two years. The area over the chain pillars has subsided a total of 1.44 feet, with 0.44 feet occurring within the last 2 years. Monitoring over the chain pillars and at the centerline shows the residual subsidence to be fairly uniform. Monitoring is continuing over both of these areas. Long-term monitoring data can be used to improve evaluation of subsidence effects on land and structures. However, coal companies will time mitigation activities depending on other factors including the threshold of structural damage, type of repair needed, and maintenance of landowner and company relations.

Jan 1, 1986

By Maria S. Adusmilli, Bhaskara A. Rao, Jorge G. C. Barros, Augusto F. Mendonca

Lateritic gold has been the object of study only for a very few years, though nuggets have been mentioned in earlier works even as early as 1984 by Hartt in Brazil. In Mato Grosso State, lateritisation is intense, as is common in all tropical forest areas of the world. Exploration has revealed the presence of recoverable "nugget gold" of variable sizes (30 - 200 gms) but frequently of good size (0 - 40 gms), especially near Cuiaba and Alta Floresta regions. In both of them the host system is a lateritised breccia indicative of a fault or shear zone breccia, though in different lithological domains. The Cuiaba occurrences are phyllitic and show a profile as follows, from top to bottom: 1) Compact ferralite crust. 2) Oolitic to pisolitic compact crust (+ some gold). 3) Mottled concretionary laterite crust. 4) Lateritised "eluvial material" (gold nuggets). 5) Mottled patchy to banded laterite. 6) Banded lateritised phyllite with lenticular to banded goethite. 7) Altered red goethitic phyllite, with quartz veins (+ fine gold). 8) Unaltered grey phyllite with quartz veins (Protore). The Alta Floresta-Juruena River occurrences are volcano-sedimentary and show a profile as follows: 1) Deep brown siltitic, argillaceous and arenaceous material with organic matter (+ gold). 2) Modular and concretionary laterite, compact and indurated, with arsenophyrite in quartz fragments (gold nuggets). 3) Band with silty-clayey matrix and arenaceous in nature. 4) Bedrock meta-arcosian arenite. 5) Volcano-sedimentary with rhyodacites and andesitic basalts, with intercalations of arkosic and greywacke nature. Breccias and quartz veins, and granites associated in different portions (Protore).

Jan 1, 1988

Iran possesses very large copper resources, estimated to contain around 4-5% of the world's known copper inventory. There are several small private sector copper mining operating in the country, but Iran's copper industry is dominated by the state-owned National Iranian Copper Industries Company, which operates the world-class Sar-Cheshmeh open-pit Mine. This mine was developed in 1970s before the 1979 Islamic Revelation by the Atlantic Richfield Company (ARCO), the former Anaconda Copper Mining Company. Current Iran?s copper cathode production is about 250,000 mtpa and recently it is targeted to reach to 700.000 t by 2014. The required finance for this target is estimated US $2.25 -b, i.e. US $5000 for each tonne capacity. The copper content of the mineable reserves of the country is estimated about 19 Mt. It is not unlikely this amount increases in close future. Currently, almost 30 projects consist of mine, concentrator, smelter, refinery, acid plant, leaching, bio-leaching are underway. These projects are a golden opportunity for the local and foreign companies, but the recent sanctions are very challenging that all studied in this paper.

Jan 1, 2012

By Glenn Melchert, Paul Eger, Jon Wagner, Dave Antonson, John Folman

Current approaches to reclaiming acid generating tailings include permanent water cover or encapsulation with various synthetic liners and/or clay. Although these methods can be effective, some ongoing maintenance will be required in perpetuity to ensure that water levels are adequately maintained or that the integrity of any capping system is protected. The successful creation of wetlands in tailings basins offers the possibility of creating a stable environment for the tailings with minimal maintenance. Acid-generating tailings from a massive zinc sulfide deposit in Winston Lake, Ontario, were placed in small cylindrical tanks to examine the feasibility and effectiveness of creating wetlands and mitigating acid and metal release. Two uncovered controls were established in addition to the five treatments, which were done in duplicate. Each wetland tank was 117 cm in diameter and contained 6 1 cm of tailings. Treatments included 61 cm cover of wetland soil, 61 cm of glacial till, 61 cm of tailings, and two tanks with 71 cm of water. One of the water covers included the aquatic macrophytes: Elodea canadensis, Potamegeton sp., and Ceratophyllum demersum. Cattails (Typha latifolia) were planted in the plots with substrate cover, and the initial water level was set at ten centimeters. The pH within the tailings in the treated tanks generally ranged between 6.0 and 6.5 and zinc concentration ranged from 0.02 to 0.1 mg/L. The drainage from the controls had an average pH of 3.3, and 7,700 mg/L of zinc.

Jan 1, 2000

By Ruifeng Li, Yanghui Ren, Hua Gao

"Since entering the new century, China’s coal industry has witnessed the rapid development, and provided a reliable energy supply for the national economic and social development. But after the “golden decade” of rapid development, the coal industry now is facing overcapacity, low industrial concentration and production efficiency, high pressure of production safety and environmental protection and other prominent issues. Based on defining the connotation of highly-efficient recovery of coal resources, this paper established the relevant 8 indicators to reflect the highly-efficient recovery level of coal resources, summarized the present situation of China's coal resources recovery and the main problems, analyzed the development environment of China's coal industry under the new situation, and finally put forward the strategic measures to promote highly-efficient recovery of coal resources in China.1. Background Coal is the main energy in China. Since entering the new century, China's coal industry has made significant progress, and the level of production safety, resource recovery rate and mining mechanization increased significantly, which provided a reliable energy supply for the rapid development of the national economy. However, due to the changes of China's economic environment, slow growth of energy demand and other factors, some prominent contradictions in the coal industry have significantly restricted the healthy development of the industry. The first problem is serious overcapacity. In the past few years, 16 industries including coal, electric power, chemical and others have invested in coal mines. It is reported (Han 2016) that only during the nine years from 2005 to 2014, the fixed assets of coal industry increased totally more than 3.3 trillion RMB, which brought a large number of production capacity. Affected by the slowdown of economic growth and energy structure adjustment, Chinese coal demand has reached the peak platform and caused the overcapacity of coal supply, so shutting down the backward capacity is the most important task in the future. The second problem is the low efficiency of coal production. There are about 4.3 million coal mine workers in China, and the annual coal production per capita is less than 900 tons, while it was reported (EIA 2016) that the annual production per capita in the United States is more than 10 thousand tons. The third problem is that the green coal resources are not rich. Among the 1.53 trillion tons proven reserves, only about one third are green coal resources in accordance with the principle of ""safety, technology, environment and economy"". The coal resources with high quality and easily mining conditions are not abundant."

Jan 1, 2017

Steady state simulation has become a highly effective approach to the optimization of existing mineral processing plants and the design of new facilities. Accurate phenomenological models imbedded in user-friendly software packages make this advanced technology available to the mineral processing engineer. The new version 2.0 of the USIM PAC software package contains many improved features, and a new Windows 3 graphics interface. The main features include Objective-Driven Simulation, new fields of application, improved data processing algorithms and improvements in the design and optimization capabilities.

Jan 1, 1992

By Nicola Beltrandi, Andrea Pigorini, Holad Mohamed Dahir, Ezio Pedone

"Genoa is a very distinctive city located between mountains and the sea and infrastructural upgrading works often have to deal with the intersection of existing infrastructures. This is the case for the new railway tunnel construction between the stations of Brignole and Principe which under-cross two existing double-track tunnels in operation. The latter have been constructed with masonry bricks and the vertical distance between old and new tunnels is approximately 1m. Due to rock characteristics and the urban environment, stability and vibrations control are the main issues. Consolidation work with the fore-poling method and a specific sequence of excavation, primary lining and final lining support have been designed to assure stability and settlement control. A hard rock road-header has been used to assure vibration control. Finally, a real time monitoring has been implemented. The article presents monitoring and back-analysis results of the under-crossing of the existing tunnels. GENERAL LAYOUT OF WORKS The Genoa railway junction constitutes an integral part of the Ventimiglia-Genoa-Novara-Milan railway line route and it is included amongst the railway systems of the Tyrrhenian-Northern European multi-modal corridor (corridor of the two seas or corridor VII Genoa-Rotterdam). The main aims of the project concern the upgrading of the existing lines and the separation of the long-distance passenger and freight traffic flows from those of a regional and metropolitan type. The project includes: •,Completion of the connection with the port of Genoa Voltri and the Italy-France coastal route. •,Interconnection with the future Terzo Valico dei Giovi mountain pass route towards Milan. •,Upgrading of the Genoa Voltri – Genoa Brignole main line to four/six tracks. Rearrangement of the systems at the Genoa Voltri, Genoa Sampierdarena and Genoa Brignole Stations, reorganisation of the services in the Genoa Terralba area and interchangeability with the metropolitan system complete the design activities. The contract which includes civil and technology works is divided into four construction lots (ref. Figure 1):"

Jan 1, 2016

By C. R. Nailler

Two recently published papers describing the use of psychological tests for selection and placement of coal mine personnel have created considerable interest within the Coal Industry, one paper, published in the April 1957 "Mining Congress Journal," entitled "Personnel Evaluation and Training," discusses the use of tests by the Christopher Coal Company, The second paper, published in the "West -Virginia Coal Mining Institute's 1957 Report" and in the September 1957 "Coal Age," entitled "Testing to Select Better Personnel for Coal Mining Today," outlines Hanna Coal Company's test and selection procedures. Since these rather detailed sources are readily available, and to avoid repetition of the material in them, we will confine this paper to a very brief review of the essential steps already taken by these companies and a more extensive look at newer material. Briefly, the Personnel Managers, Mr. Harold L, Durrett and Mr. Albert M,. Rowe, of the Hanna Coal Company and Christopher Coal Company, in conjunction with Dr. Quin F, Curtis, Head of the Psychology Department of West Virginia University, developed two different groups oftests for coal mine personnel, The first group oftests was designed to assist in the selection of supervisors. These tests of the supervisory group were "The California Short Form Test of Mental Maturity - Advanced Series," which gave an I.Q. rating, and the second test is known as "The Minnesota Multiphasic Personality Inventory," which measures several personality characteristics, These tests must be given, grade, and interpreted by a person trained in psychological testing. As a result of testing all of Christopher's supervisory employees (seventy in number) by this method, and then comparing the individual results with the individual ratings of the foremen on the job, a so-called foremen's scale was developed. If this resulting foremen's scale had been used to select the foremen who were rated as, the best men in on-the-job performance, it would have correctly identified seventy-four percent of that group.

Jan 1, 1958

By Hans Ehdwall, Erling Strandon, Friedrich Steinhäusler, Victor A. Leach

INTRODUCTION The basis for any measures in radiation protection is the quantitative assessment of the radiation exposure. Due to the extensive requirement in health physics manpower and related cost it is necessary to develop certain criteria regarding the necessity of monitoring and the selection of population groups to be monitored. Depending on the overall objective of the particular programme, the specific requirements for the measurement of atmospheric levels of radon, thoron and their daughters for practical radiation protection purposes differ significantly for those in the case of research applications, such as use of data for epidemiological studies. As part of the OECD-NEA Programme on Radon Dosimetry and Monitoring Task Group 1 reviewed available models for lung dosimetry in the case of inhalation of radon 222, radon 220 and their daughters (James et al., 1981). Using defined reference atmospheres for underground- and open-pit mining conditions as well as for dwellings, normalized conversion factors were calculated for the mean bronchial dose (mGy) per Working Level Month exposure (WLM). Task Group 2 discussed the features and adequacy of the Working Level (WL)-concept as a physical correlative of the absorbed lung dose and its limits of confidence and accuracy (Johnson and Leach, 1981). The WL-concept was found acceptable for radiation protection purposes provided that modifying factors like particle size, unattached fraction and respiratory minute volume did not cause the effective dose equivalent per WLM as calculated by either the James-Birchall or Jacobi-Eisfeld lung models to be more than 50 % above that given by ICRP of 0.01 Sv/WLM. For application in epidemiological studies the WLconcept is considered acceptable if the calculated absorbed dose to the tissue does not vary by more than 50 % (at the 95 % confidence level) from that given for defined reference conditions. In the following, objectives and requirements for the measurement of radon, thoron and their daughters are discussed for operational health physics routine and special research applications according to the scheme outlined in Fig. 1.

Jan 1, 1981

By George J. Dvorznak, Robert W. Waytulonis

The Bureau of Mines is conducting a research project in cooperation with the Mine Safety and Health Administration (MSHA). Mining companies, and equipment manufacturers are also participating through the Colorado Mining Association (CMA). The objectives of this cooperative research project are to determine the practicality of coupling a dry exhaust conditioning system (dry system) and diesel particulate filter (DPF) to make an integrated control system, and to determine the effectiveness and durability of the integrated system in an underground coal mine. Diesel-powered mining machines must be equipped with control devices to reduce surface and exhaust temperatures to safe levels and prevent flames and sparks from being emitted to the mine atmosphere. Diesel exhaust-gas water scrubbers have been successfully used for many years but they have several disadvantages; they are large, consume large quantities of water, and require frequent maintenance to remain functional. Additionally, diesel exhaust is a source of noxious gases and particulate matter. Particulate emissions are composed primarily of small carbon particles with absorbed hydrocarbons and they are almost entirely respirable in size. Even an engine in good mechanical condition can emit up to 400 mg/cu m of respirable particulate matter. A dry system for control of diesel fire and explosion hazards, coupled to a DPF, promises to be a complete control system for diesel engines. The dry system cools the exhaust and suppresses sparks and flame with a heat exchanger and flame and spark traps. The conditioner is smaller, consumes no water, and requires less maintenance than a comparable water scrubber. The DPF uses a ceramic substrate as a wall-flow filter and is very efficient at collecting exhaust particles. Average particulate mass collection efficiency is 90%. This report describes a cooperative research project to combine the dry system with the DPF, conduct performance tests on the integrated system at Bureau and MSHA 1aboratory facilities, and conduct field tests of the system on a production machine in an underground coal mine.

Jan 1, 1987

By Chuck R. McLendon

A new face ventilation system was needed at the Allied Chemical Trona mine, near Green River, Wyoming. The development of an exhaust manifold face ventilation system came from a need to reduce the dust and noise concentration level while maintaining methane control at the continuous miner working face. Dust laden air from a heading being driven by a continuous miner was contaminating the intake air in the mine around the roof bolter operator and adjacent headings. Each working heading was exhausted into the last open crosscut by a face fan. A face fan would contaminate the adjacent downstream heading with dust-laden air until a high dust concentration developed in the final entry before the returns. A face ventilation system was needed to give the exhaust of each heading an individual path to the return air. In addition, the system could not interfere with the present room and pillar mining process. A manifold system of rigid duct ventilation tubing was designed using the existing fans in a parallel arrangement. Each system was to consist of the rigid duct tubing in three headings junctioned together at the last open crosscut and exhausted at a common branch in the return air. Each heading was to have its own damper (or valve) so that air could be directed where it was most needed. The system was installed using both round and oval rigid duct ventilation tubing to minimize head loss and to allow proper ground clearance for mining machinery. Two fans in parallel were used to exhaust three headings. By adjusting the valves at each heading, up to 18.0 kcfm (9.36 cu m per sec) could be exhausted from one heading and still keep the methane level controlled in the other two headings. The manifold exhaust system has proven to be an efficient, long lasting ventilation system at the Alchem Mine. It has reduced the dust and noise exposure levels at the working faces while keeping the methane level under control.

Jan 1, 1980

By Dan Witkowsky

In an increasingly environmentally conscious world, mining's importance to society has often been misunderstood and even maligned by the public. Extreme and impractical ideas have often been presented to children because of the lack of accurate, timely resource materials available to educators. In the late 1960s. two mining engineers, S.P. "Pi" Warren and C.L. "Lindy" Barker, became aware of this situation. They proposed to develop a summer field course to provide a factual overview of the minerals industry for teachers. The pair believed that teachers could become better informed to educate students, and future generations, about mining. These two Colorado Mining Association (CMA) members felt that such a course could reduce much of the misunderstanding about this vital industry. This could be done by providing a balanced perspective of mining, not only for kindergarten-through-grade-12 teachers, but also for the students they would be teaching during their careers. Students who better understood the minerals industry could better formulate an unbiased view of it. The course would seek recognized authorities from industry, academia and government who would lecture in their respective fields of expertise. The course would provide a total concept of the coal, aggregate, metals and industrial minerals industries. It would include geology, geophysics, exploration, mining, processing, marketing, product applications, economic, mining history, careers, and environmental responsiblity. When possible, site visits would permit educators to view operations and to meet the men and women who are industry leaders. Teachers would pay a small tuition fee. The balance of the program expenses for each teacher would be paid through scholarships provided by industry and individuals. The "total concept" idea obtained the support of the minerals industry. The support of CMA's Education Committee and the Colorado School of Mines (CSM) was obtained in 1968. Colorado's Commission on Higher Education approved teacher recertification credits through CSM's Office of Special Progams and Continuing Education for those successfully completing the program. The first six-week series of classes presenting the total concept of the indus¬try was held at CSM in 1969. In 1977, the CMA Education Foundation Inc. (CMAEF) was established as a Colorado nonprofit corporation. The "Total Concept of the Mining Industry" (Total Concept) course was placed under its sponsorship. CMAEF is dedicated toward this continuing education program (Table 1). In 1994, the course was streamlined to four-weeks for six hours recertification credit.

Jan 1, 1997

By Brian Flintoff

SCOTT COULTER: Our second speaker today is Brian Flintoff. Brian graduated from the University of Alberta in 1973 with a master's of science degree and worked as a project metallurgist at Brenda Mines until 1977. He returned to the University of Alberta in late 1977 to work on his Ph.D. and later joined the faculty of engineering in 1980, leaving in 1988 to rejoin Brenda in the newly formed process technology division. In 1998 he left Svedala-Brenda to take a position with Simons International's newly formed enterprise development services group. His topic today is "People: Reduce, Reuse, and Recycle." INTRODUCTION BRIAN FLINTOFF: Historically, the mining industry has relied on the people within a corporation to get things done. The culture of most companies was one of a slow but sure development of people, processes, equipment, and technology. Many of the larger companies supported in-house engineering and research organizations. However, the metal market pressures of the 1980s and the emergence of the global economy in the late '80s and early '90s put enormous financial pressures on the industry. As the old adage says, "necessity is the mother of invention," and the mining industry, like many others, has undergone a transformation. A cornerstone element of the transformation was the downsizing (or right-sizing) that was calculated to "trim the fat" from the capital and operating budgets. The goal was and is to find the highest sustainable operating profit.' While I'm sure one can find examples of losers (e.g., those who can be classified as suffering from corporate anorexia or institutional Alzheimer's) in such business reengineering efforts, there is little doubt that, on the whole, the transformation has been successful. The reality that now faces mill management is "How to do more with less?" At the risk of oversimplifying, one can look at this on two levels:

Jan 1, 1998

By Sunil Jain, Jan M. Mutmansky

As coal mining evolves in this country, underground coal is being mined at greater depth and under more difficult conditions than in the past. At the same time, economic conditions make it necessary to mine more efficiently and economically. As a result, pressures on mining companies arise on two fronts and make the job of mining coal underground very difficult. Recent improvements that have been made in health, safety and productivity have come about primarily due to improvements in existing technology and better management of all the production resources. However, this trend can continue only so far and thus innovation will be needed to continue the improvement. This paper deals with a concept that, on the surface, appears to be more efficient in terms of the costs to provide ventilation. The resulting design is oriented toward increasing the ventilation efficiency through use of a unidirectional ventilation plan but it also promises to increase recovery and decrease the requirements for development entries. To analyze this ventilation concept, two mine layouts with a similar production schedule were planned in a hypothetical 1.83 m (6 ft) coal seam. The first alternative analyzed uses a traditional approach to ventilation with centrally located shafts and a bidirectional ventilation pattern. Using this system, it is necessary to use large-diameter shafts and a large number of main entries. Using the same assumptions on ventilation requirements, the second alternative utilizes unidirectional ventilation whenever possible, a smaller number of main entries and small-diameter blind-bored shafts in the bleeder areas. The comparative analysis is performed using PSU/TDMVS, a computer network analysis program that is capable of determining the ventilation power requirements at any time in the mine life and converting the costs to a present value. The economic analysis is then completed by including the shaft-sinking and entry-driving costs and the costs associated with the recovery of coal that are directly related to the change in the ventilation system. The results are summarized on a present-value basis.

Jan 1, 1987

At first glance the staid Joralemon background does not seem to equate with the life of adventure that irresistibly called me for over 70 years. But my ancestors had their adventures too. My father's family were Dutch Reformed Protestants who had energy or daring enough to come to America to escape the Catholic persecution that followed the Massacre of St. Bartholemew. The first Joralemon came from Friesland to New Amsterdam m 1636, just after Peter Stuyvesant. My father's mother's family, the Berdans, were French Huguenots who came to northern New Jersey only a little later to escape the Catholic domination in France. Some say that the first Berdan to come to America was given all the land between the Passaic and the Hacken-sack Rivers by King James. Whatever, the Berdan family settled there and was able to make a scanty living by farming and selling their produce in Manhattan. The spirit of adventure in my mother's family was just as tenuous. Gamaliel Beaman was pastor of a shipload of Puritans who came to Massachusetts in 1636. Gamaliel's descendents were peaceful farmers and some ministers in New England and later New York State. They had got all of the adventure out of their systems in the long and dangerous voyage across the Atlantic to escape religious persecution. The Joralemons and the Berdans married into families that had been in America almost as long as they had. On my father's side the Berdans, Doremus, DeGreys, Vanderbeeks, and Varicks showed by their names their Dutch or French Huguenot stock. The only one who achieved any fame was Peter Varick, who was George Washington's military secretary during the American Revolution. After this he was nine times mayor of New York and was one of the founders of Kings College, later Columbia University. He was responsible for one of my few ancestral claims to distinction. When the Marquis de Lafayette made a fare-

Jan 1, 1976

By James W. Martin, Robert R. Faddick

INTRODUCTION Virtually every sector of society in our country feels the impact of tunnels, either through the transportation of water, commodities, or people. The economic implications are staggering. The Committee on Rapid Excavation (1) reported that during the near future, 1968-1975, underground excavation activity will comprise 946 miles of tunnels (subways: 85 miles; underground urban highways: 123 miles; intercity highway tunnels: 210 miles; water supply tunnels: 528 miles) and 5,119 million tons of crude ore; metals: 874 million tons; nonmetals: 899 million tons; and coal: 3,346 million tons. It is estimated that the cumulative demand for underground excavation in the decade 1970-1979 will be 13 billion dollars for construction-oriented demand and 16 billion dollars for mining-oriented demand. The respective figures for the decade 1980-1989 are estimated at 22 billion dollars and 18 billion dollars. Of the many advantages claimed for tunnels (2, 3, 4, 5) the environmental considerations are becoming increasingly important. Transportation tunnels particularly for rapid transit systems, offer reductions in noise pollution and air pollution while improving aesthetics and optimizing land use (fewer problems of right-of-way and disruption of utilities). Considerable interest has been shown recently in sub-surface construction and mining (6, 7, 8). Recognizing the future demands for tunnels has led to considerable study of methods to improve rates of tunnel advance per day, safety, and the overall economics. The search for higher rates of advance has Led away from what has heap termed conventional methods (drilling

Jan 1, 1974

By Charles E. Joachim

Current Army tunnel destruction criteria (1) are based on limited nuclear-explosive (NE) and high-explosive (HE) test data. The PILE DRIVER (2) and HARDHAT (3) events investigated tunnel and support system response where yields were relatively large and tunnel diameter small compared to typical underground openings and localized stress fields of low yield weapons. Some limited tunnel destruction information was obtained from underground events of the PLUMBBOB and HARDTACK II Series (4). These events used access drifts which were designed to be self closing at the weapon point. The limited NE data are augmented by HE results from the Underground Explosion Test (UET) Program, a series of model and prototype-scale experiments in granite and sandstone (5). Weapon standoff distances (charge c.g. to tunnel wall) were at or near the maximum for major damage. Limited tunnel destruction was produced by a series of hasty and deliberate tests (6) on abandoned railroad tunnels in basalt. Additional HE data were obtained from model tests at the Waterways Experiment Station (WES) (7) using 2.1 MJ (2 lb) TNT charges and tunnel diameters varying from 3 to 17 cm (1.2 to 6.6 in). Recent laboratory scale HE experiments (8) conducted at the WES under the ESSEX program investigated the effects of tunnel diameter, standoff distance, charge confinement, material strength and to a limited extent, tunnel spacing and liner strength variations on tunnel damage. This paper summarizes the analysis conducted to develop predictions for the effects of low-yield nuclear weapons against tunnels and underground openings in rock.

Jan 1, 1979