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By Walter E. Cook

BOB FALCONER: Without further ado I'm going to introduce our first speaker, Walt Cook. Walt is president of Strata Resources and is here with his business partner Joe Nenni. Joe would you stand up here. You'll be on the tag-team with Walt. Walt and Joe are in a consulting business associated with coal as well as metal and nonmetal industries. Their presentation will be on gainsharing. WALTER COOK: How many of you have gainsharing plans in place currently at your location? [show of hands] A considerable number-more than about half the room. Of those plans, how many of them do you consider as meeting your needs and being successful? [show of hands, far fewer, general audience laughter] You have all at least heard the word "gainsharing." Some of you undoubtedly aren't quite sure what gainsharing is, while others obviously have gainsharing plans in place and are looking for ways to improve them. In the short time I have now I'll be able to give you a precursory look at gainsharing and some brief ideas on where to look to improve your current plans. Over the years, I've found that it is often best to explain gainsharing by comparing it to other forms of employee compensation

Jan 1, 1998

By Teena Redhorse, David Tsztoo, Anthony Yu

"Since ancient times, storing and conveying water via underground water systems and tunnels has been touted for its strategic advantages. Underground cisterns and tunnels assured protection of essential fresh water supplies from man made contamination and especially from enemies who would gain an advantage by disrupting an adversary’s water supply in a siege. Modern day engineers do not usually specify tunnels for reasons of avoiding deliberate contamination or siege — however, they are just as enamored with the idea of building tunnels for water conveyances.Such was the case for the San Francisco Public Utilities Commission (SFPUC). The SFPUC provides drinking water to 2.6 million residential, commercial and industrial customers in the San Francisco Bay Area. The SFPUC’s water system includes 257 km (160 miles) of transmission pipelines and tunnels from the SFPUC’s largest reservoir, the Hetch Hetchy Reservoir inside Yosemite National Park, to San Francisco. About 129 km (80 miles) of the system consist of tunnels. A 30-km (19-mile) section of the tunnel network, called the Mountain Tunnel, was thought to be at risk of a catastrophic failure in its concrete-lined section of 18 km (11 miles). For much of the project planning process, a new replacement tunnel was presumed to be required according to the tunnel planners.Originally constructed between 1917 and 1925, the Mountain Tunnel has been in continuous service since 1925. The 30-km (19-mile) tunnel is located downstream of the Hetch Hetchy Reservoir water source in Yosemite National Park, between the Early Intake and Priest Reservoir (Fig. 1). Approximately 18 km (11 miles) of the tunnel is lined with unreinforced concrete. Though the condition of the tunnel was being monitored through water sampling and periodic inspections, there was growing concern that the tunnel lining was at risk of a partial collapse that could interrupt water delivery for up to nine months. The SFPUC was faced with a decision to construct a new bypass tunnel to replace the lined section of the Mountain Tunnel or to rehabilitate the existing tunnel."

Jan 6, 2018

By Carl Erickson

The term shortwall mining is somewhat of a mis¬nomer. It may infer a longwall mining system, but of much shorter face length. Actually, continuous pillar mining is a more descriptive term. Coal is mined using a continuous miner as would be done in pillar extrac¬tion, but with the addition of roof supports to control the caving. Face length on such a system typically is 46 to 61 m (150 to 200 ft). The coal is cut in front of the roof supports in the same direction as with a long¬wall shearing machine or plow, but it is mined with a continuous miner and shuttle cars of the same type as used in continuous mining. ROOF SUPPORTS Roof supports for shortwall mining must be con¬siderably larger than those used for longwall mining because of the additional roof to be supported by the wider 2.6- to 3.4-m (81/2- to 11-ft) cut of the continuous miner. Capacities of shortwall chocks in current use vary from about 454 to 726 t (500 to 800 st). The higher capacity as compared to longwall roof supports is needed primarily because of (1) the greater support length, hence more roof weight, and (2) the presence of draw slate in the eastern coal seams, where shortwall is being used. The most popular shortwall support currently used is the four-leg 590 t (650 st) model. This support is shown in Fig. 1. The price of this support is approxi¬mately $25,000 each. As shown in Fig. 1, the shortwall chock incorporates an unusually long forward bar that has an additional hydraulically operated extension bar to provide face support for the wide miner cut. METHOD OF OPERATION Mining Sequence In shortwall mining, two or three (depending upon the chock design) move up cycles of the chock are needed because of the miner cut width. Fig. 2 depicts the five steps required to complete the move of chock and spill plate using a miner that takes a 3.3-m (10-ft,

Jan 1, 1982

By W. T. Robertson

My charge is to review briefly "Coal In The Electric Utility Industry - Present and Future." Thus, I will not dwell on the overall energy picture, other than to express what most others involved in the energy picture know - we're in trouble! Several years ago, speaking to another engineering society, I said, "Much has been and yet will be said and written about the energy situation in our Country." What an understatement! The energy question has reached crisis proportions and is a top priority item at the highest level of government, Unfortunately, it will be in that situation for some time to come. Many factors created this complex problem, and we all share some of the blame. But I am perplexed when I read in the popular press that environmental factors are unrelated to the energy crisis when I know this to be untrue. In the recent past all forms of energy have been cast in the role of villain, particularly coal with its problems of surface mining, mine safety, acid water drainage, sulfur content, and a multitude of other adverse factors relating to the environment in one way or another. As you know, the sulfur situation has led to the closing of numerous mines, resulting in the lessening of our mining capacity. Today, along the Eastern Seaboard, 60 to 70 million tons of coal are displaced by imported oil, primarily to meet air standards. Even in the Midwest, utilities sitting on enormous coal reserves are converting to other fuels or hauling low sulfur coal thousands of miles from the western Mountain States. [We will hear more about this coal from another speaker on the program this morning.]

Jan 1, 1973

Up to the middle of 19 14, when I had reached what seemed like the advanced age of 30, I had enjoyed far more than my share of success and a lot of minor adventure. But the exciting experiences in distant lands that Soldiers of Fortune had made me long for had not yet materialized. And I had not accomplished the two goals that Mrs. Hughes' geography class at Belmont had set up for me. They were to see In its tropical home the enormous yellow bill of the toucan bird and to ride on a straw "bolsa" on Lake Titicaca. These aims were gratified In the next five years that were the epitome of "romance" in its German connotation of facts seen through the rosy glasses of imagination. Dr. Louis Ricketts was to a large extent responsible for my opportunity. I had been lucky enough to do a lot of work for and with the Doctor, as he was affectionately called by the mining men of the southwest. My association was in connection with his work with John Greenway on the complex metallurgical problems at Ajo. Soon after the Ajo investigation Ricketts had been made chief consultant for the Anaconda Copper Co. When Anaconda decided to undertake a cam- paign of exploration of the west coast of South America Dr. Ricketts thought of me and arranged with Greenway to give me a leave of absence from my Calumet and Arizona job. It took three days in New York in June 1914 to arrange the expedition. Ben Thayer, executive vice president of Anaconda, did most of the planning and I was to report to him. T.H. France, a 45-year-old mining engineer who had been driven out of Mexico by the Madera Revolution, was to accompany and help me. He spoke excellent Spanish and his years of Mexican experience had taught him how to get along with Latin Americans. He went ahead to Bolivia, our first target, to get an idea of the country and the problems. This was lucky as I hardly knew where Bolivia was.

Jan 1, 1976

By Steve Kral

In December 2013, the Colorado Department of Transportation (CDOT) completed the widening of the eastbound tunnel on Interstate 70 (I-70) from two lanes to three. Work on the westbound tunnel began earlier this year and is scheduled for completion in December. The Twin Tunnels project is located in the mountains about 55 km (35 miles) west of Denver. They were bored during the 1960s when I-70 was being built and became the main access to Colorado?s growing number of ski areas and the state?s Western Slope. Throughout the decades following their construction, traffic on I-70 continued to increase and now the tunnels have a major bottleneck. Com-mutes to and from the mountain resorts, particularly on weekends, have become long and slow. Adding a third lane through the tunnels will help alleviate the congestion. (A complete report on the project can be found in T&UC, December 2013, page 61.) Once the eastbound tunnel was completed late last year, CDOT authorized the funding to begin work on the westbound side. That made economic sense, as the equipment used on the eastbound tunnel needed to only be shifted across I-70 to begin work on the westbound side, rather than removing it in December and bringing it back in March when construction began on the westbound tunnel. Work on the westbound tunnel uses essentially the methods that were used on the eastbound tunnel ? removal of the existing concrete lining and using drill-and-blast methods for tunneling widening. The main difference between the two tunnels is that the westbound side requires more blasting on both ends to widen I-70 to three lanes.

By M. B. Haggerty, Joe Welna

The Minnesota Department of Transportation is constructing a stormwater storage facility (SSF) along Interstate 35W (I35W) south of downtown Minneapolis, MN. The project will provide storm surge capacity reducing the frequency with which major precipitation events result in flooding of I35W. The design consists of six, 42-foot diameter, 90-foot deep, adjacent underground shafts providing 14.7-acre feet of storage. Construction challenges include high groundwater with variable glacial outwash deposits. Constructability and ground variability were managed using construction manager general contractor (CMGC) project delivery. CMGC provides an environment for collaboration and innovation starting in the design phase and carrying through construction. This paper provides an overview of key efficiencies and collaboration examples implemented on the I35WSSF project which were aided by CMGC delivery.

Jun 13, 2023

By Chris A. Fleming, Daan Seymore

The Golden Jubilee Mine in South Africa is the first mine in the Western World to introduce resin-in­pulp technology for the recovery of gold from a cyanide-leached slurry. Located in the Eastern Transvaal region of the country, the plant processes approximately 375 metric tons• of ore per day, of which over 90 per cent is mined in an open pit adjacent to the metaflurgical plant, while the remaining 5 to 10 per cent is trucl<ed in from two small high-grade deposits, located about 10 kilometers from the plant. The gold grade in the open pit is about 1 git, while the values m the two high-grade deposits range between 5 and 15 git. At the current treatment rate, the proven reserves m the three locations will last about another 10 years. Early testwork indicated that the ore was not well suited to conventional filtration processing or to heap leaching because of its high cfay content, and that carbon-m-pulp (CIP) would probably prove to be the most viable metallurgical route. Tcstwork to establish the feasibility of CIP for this application was carried out at Mintek in 1985. This worl<, which was based on batch-leaching and carbon-loading tests, indicated that CIP was technically feasible, but that both the rate of gold loading and the gold-loading capacity of the carbon were inferior to those obtained with Witwatersrand ores. The poor adsorption characteristics of the carbon were attributed to the abnormally high concentration of natural organic compounds (humates and fulvates) in the ore. Batch tests were therefore also carried out with strong-base resins, since resins are known (1] to be far less susceptible to organic fouling than is activated carbon. The results were very promising, and pointed to fast kinetics and a high loading capacity. (Fig. 1 ). Notwithstanding these findings, it was decided to recover gold with activated carbon at Golden Jubilee Mine because the CIP process was, by then, well established in South Africa and elsewhere in the world, whereas resin-in-pulp (RIP) was unproven technology. The r>lant was commissioned in September 1986 and, for 18 months, operated in a carbon-in-leach (CIL) configuration, i.e. with a total of . six leach tanks, the last four of which contained activated carbon. As could have been predicted from the laboratory results, the performance of the CIL plant was generally poor, low gold loadings on the carbon (less than 1500 git) and high losses of soluble gold (0.2 to 0.3 p.p.m.) bemg characteristic of the operation. Consequently, it

Jan 1, 1990

By Xianyang Qiu, Xiuzhi Shi, Chen Xie, Xiaofeng Huo, Yanhai Wang

In upwards medium-deep hole cut blasting, many confinement effects exist due to the small number of free surfaces, which is mainly provided by an empty hole. If the cut blasting effect cannot meet expectations, then subsequent blasting construction will be seriously affected, and large security risks to operators in the stope can be induced. The number of free surfaces is directly related to the layout of the cutting borehole. Therefore, it is necessary to optimize the layout of the first round of cutting boreholes. Theoretical analysis, numerical simulations, and field tests were used to study the formation process of cut blasting and optimize the layout of the first round of cutting boreholes. Based on the blasting parameters in the field, LSDYNA software was used to establish cut blasting models with four kinds of borehole layouts in the first round. The RHT constitutive model was used to simulate the rock-breaking effect. The numerical results show that the cut blasting effect is optimal when Nos. 3, 5, 7, and 9 are charge holes and Nos. 1, 2, 4, 6, and 8 are empty holes. In addition, the greater the number of empty holes, the larger the release space and the better the cut blasting effect. The uniformity of the empty hole distribution, namely, the uniformity of the release space, also affects the cut blasting effect. The field results indicate that a good cut blasting effect can be achieved by optimizing the borehole layout.

Sep 7, 2023

By Aurel Goodwin

I chose the title "Let&apos;s Clear the Air" for this afternoon&apos;s presentation because it has two meanings, the literal and the figurative. Most of you know what MSHA is. Most of you know what MSHA does. And, for the most part, most of you know why. What I hope to accomplish today is to "clear the air" around our health standards, to clarify for you how MSHA views its congressional mandate under Title I Section 101(a)(6), (7), and (9) of the Mine Safety and Health Act. Asbestos, silica, radiation, noise, welding fumes, carbon monoxide, lead, hydrogen sulfide, nitrogen dioxide - the list of physical and chemical hazards encountered in the metal and nonmetal mining industry is as diversified as the industry itself, possibly even more so. In addition, miners are often exposed to several of these health hazards simultaneously.

Jan 1, 1980

By A. M. Gaudin

In the first place, let me thank you for inviting me to appear before you today to speak to you on "Mineral Industry Problems - Present and Future". It is a distinguished honor for me to have this opportunity, and I am highly appreciative of this distinction. The beautiful surroundings of Gatlinburg and the pleasantness of a summer occasion are a wonderful tonic for all of us, yet they should not blind us to the seriousness of our Industry&apos;s problems No doubt, because of my past appearances before members of the Society of Mining Engineers, at which I discussed wholly scientific topics, or research in the Applied Sciences, you may be expecting me to revert to these subjects. But I intend to venture in a field that is new to me, yet old to all of us, the field of Economics.

Jan 1, 1962

By M. Schreiner, J. Brune, D. Theisen, C. S. -J. Tsai

This study reports that routine mining activities could produce a high number of nanometer sized particles which have not been well characterized and may represent an unacknowledged exposure present in the mining environment. A preliminary survey of the particle emission from the feed-leg drilling activity was conducted in the excavations of an experimental mine. The level of particulate exposure was monitored by real time direct reading instruments include a NanoScan scanning mobility particle sizer (measurement range 10-420 nm) and an optical particle sizer (measurement range 0.3-10 μm). Particulate morphological and structural examination was conducted through transmission and scanning electron microscopy and x-ray dispersive analysis of samples collected by a thermophoretic sampler, and a novel nanoparticle sampler. The real time instrument data revealed high concentrations (> 3.5 x 106 particles/cm3) of ultrafine/nanoparticles generated from the drilling activity. Analysis of particle sampler specimens with energy-dispersive x-ray spectroscopy showed a large amount of submicron silica, spherical primary particles and agglomerated soot particles rich in carbon. Exposure to particles in the nanometer size from various sources within the mining environment may be associated with the poorly understood rise in respiratory and systemic disease among miners. INTRODUCTION Exposures to mine dust have been measured and evaluated for decades. Exposures to aerosolized dust such as coal or silica particles can cause lung and other diseases (1-7). One way that The Mine Safety and Health Administration (MSHA) characterizes inhalation exposures within the mining environment is through measuring the respirable dust mass concentration within the breathing zone of workers (8). Respirable particulate matter (RPM) is of great concern due to its ability to deposit in the alveolar region of the lungs (9-10) where it can affect respiratory function. Interventions championed by MSHA have greatly reduced the prevalence of coal workers pneumoconiosis (CWP) and progressive massive fibrosis (PMF). Although great progress has been made, the prevalence of CWP and PMF appears to be trending upwards and the measured increase in prevalence is not elucidated in RPM measurements (11-12). Though the presence and risk associated with ultrafine particles such as emission from diesel engine within the mining environment has been previously established (13-14). There is suspicion within the mining industry that this resurgence of lung disease may be due to very fine particulate matter from various source that is not properly characterized by current sampling methods. Nanometer sized particles, in the range of ultrafine particles, fall within the RPM size range and have been found to deposit in all regions of the respiratory tract (15). Nanoparticles are commonly accepted as particles that are greater than 1 nm in two or three dimensions but smaller than 100 nm (16). Once in the lungs, nanoparticles can enter the blood stream (17) and selectively affect other target organs such as the heart, liver, bone marrow, lymph nodes, spleen, and brain (15,18-19). The size of nanoparticles has been shown to correlate with their translocation behavior on secondary target organs (20-21). There is strong evidence that the clearance mechanisms used to rid the lungs of particulate matter are not as effective on nanometer sized particles, leading to a greater fraction of never-cleared particles which may enhance disease development (20). Research has demonstrated that nanometer sized particles have unique properties (22) whose adverse health impact is greater than what has been found with micrometer sized particles of the same type (23-26). The large ratio of surface area to mass compared to larger particles is believed to make nanoparticles a greater hazard. Utilizing mass to measure these types of exposure will be very difficult to accurately characterize the quantity of

Jan 1, 2019

By Lloyd E. Haight

After accepting the invitation to make this appearance today, it occurred to me that the subject matter which had been assigned to me, namely, the purpose and role of an advisor, was, contrary to what; some people might think, a controversial subject. In my brief lifetime, I have discovered that the world is full of advisors; that is to say, there are many people who undertake to render advice concerning subject matters upon which they may, or may not be qualified to speak. It shall be my purpose today to set forth what now appears to be the function of the members of the Advisory Council to the U. S. Public Land Law Review Commission; and, in so doing, I hope that I do not offend the Commission or any other-member of the Advisory Council with whom I serve. It has always been my personal conception of the role of an advisor that he should tender advice when it is requested, and then only if he has prepared himself concerning the matter upon which the advice is being given. I am sure it was the Congressional intent at the time the Public Land Law Review Commission was established indeed it was the hope. of Congress--that those of us who were to become members of the Advisory Council were informed upon certain particular subjects and then at the proper time express our opinions upon these subjects-and, by the same token, not attempt to enter opinions upon problems with which we have no experience in theory or in actuality. Some wag once said that if Columbus had had an advisory council, he would still be waiting at the dock in Spain, and there is more truth than fiction in that statement. With this problem in mind, let us examine the purpose of the Advisory Council itself.

Jan 1, 1967

By William E. Robinson

Why did it fail? My first reaction when assigned this topic was to say: because somebody "goofed"--then thank you all for letting me say those few words, then promptly sit down. All of you have been bandying this problem around for many years--so all of a sudden I should come up with the solution. Well, While I might not provide you with your particular answer, I think I can show you some of the resolutions to it. Somewhere along your path of experience you may have discovered that a good formula for starting a fight is to tell a group of dedicated (Nordberg Crusher) users they should be using (Allis-Chalmers), or a group of (Allis-Chalmers) &apos;users they should be a (Traylor). Now, if you really want a melee, get both groups together and tell them they should be using a (Stedman Cage Mill). This is one sure way you can learn how great minds arrive at logical, well thought-out conclusions, based on all the relevant facts. Why did it fail? I could go on for hours giving you specific reasons why. One of my engineering professors used to start his new class off each year by writing on the blackboard--four and two, then turn to the class and ask: What is the problem? One brave scholar would venture to answer 8. His head would shake no. Another would dare 6. Again, a head shake. Now that the ball had gotten rolling, a number would vocally decide it had to be two, which produced only another shake of the head--no. All of them had missed the question he had asked : What is the problem? What he had gotten ,were some of the possible answers to the problem.

Jan 1, 1977

By George White

On June 25, 1876 Lt. Colonel George Armstrong Custer led the Seventh U.S. Cavalry Regiment., comprising 31 officers and 637 enlisted men, into the valley of the Little Big Horn River in southern Montana. His assigned mission was a reconnaissance-in- force to locate the Indians reported to be assemblying in that area. Custer was extremely successful in locating the Indians. Unfortunately he located more than 3000 Cheyenne and Sioux under the leadership of the great war chiefs Crazy Horse and Gall. Custer&apos;s entire battalion of more than 200 men was annihilated; there were no survivors. While I don&apos;t seriously suggest that things will be all that bad in the uranium industry, I do suggest that some very fundamental changes have occurred in the uranium market. Conventional thinking based on past truths will no longer suffice. Geology, economics, politics, nuclear growth pat terns, technology, and utility attitudes have all changed. New thinking is in order. It is at this point that I would offer my usual disclaimer. My views regarding the future are simply that--my personal views. My belief that certain events will come to pass does not mean I view those events as appropriate, wise, good, equitable, or economic.

Jan 1, 1985

By D. R. Nagaraj

Editor&apos;s note: Minerals concentration is a disparate area, one involving many disciplines. Flotation, flocculation, reagents, microbial processes, gravity and magnetic separation, and the areas of coal and oil shale - concentration is relevant to all of these. In his article, Nagaraj reviews the latest developments and findings in concentration that have ocurred during the past year. Flotation The Monograph Series "Development in Mineral Processing," (Elsevier, 1985) was devoted to "Flotation of Sulfide Minerals." This volume has 26 articles covering the aspects of flotation chemistry, process development, plant design and equipment, and modeling and process control. The numerous articles on sulfide flotation had one recurring theme - the role of electrochemical processes and redox potentials in flotation and depression. Significant advances have been made in this area. A differential desorption-reflotation process was developed for the beneficiation of calcitic phosphate pebble (Hsieh and Lehr, Industrial Engineering and Chemistry, 1985). The carbonate and phosphate minerals were first separated from silica using fatty acid and the modifiers diphosphonic acid and HF. The collector on phosphate was then desorbed using sulfuric acid, and calcite was selectively floated without additional collector. A two-stage conditioning - initially at pH 10, followed by that at pH < 4.5 - with sodium oleate was developed to improve the separation between apatite and dolomite (Moudgil and Chanchani, Minerals and Metallurgical Processing, MMP, 1985). Separation of Mussorie rock phosphate in India from gangue calcite, dolomite, silicates, pyrite, and carbonaceous impurities was achieved with a three-stage flotation only on -75 µm (-200 mesh) fraction (Vaman Rao et al., International Journal of Mineral Processing, IJMP, 1985). The separation of fine SiC whiskers from other products of coked rice hulls by immiscible liquid and froth flotation was achieved using M1BC, pine oil, and mineral spirits (Parekh and Goldberger, MMP, 1985). Flotation was more economical. The carrier flotation separation of hematite fines from quartz fines was effected using coarse hematite as a carrier and oleic acid and ferric chloride (Cristoveanu and Meech, CIM Bulletin, 1985). Potash recovery from brines by laboratory-pan solar evaporation and amine flotation was discussed by Foot and Juiatt (Salts and Brines &apos;85, Proceedings, 1985). Flotation in a 45-kg/h (99-lb per hour) unit recovered more than 95% of the potash in schoenite and sylvite concentrates containing 28% and 62% K2O, respectively. The effects of fresh concrete into cement and aggregate by a single-step flotation process in aqueous suspension was described (Naegle, Chemical Engineering Science, 1985). The physico-chemical principles for the selective separation of proteins from mixtures using flotation were discussed by Ostermaier and Dobias (Colloids & Surfactants, 1985). Selective flocculation of hematite from silica was studied by Bagster and Mcllvenny (IJMP, 1985). Selective flocculation was more favorable with more highly charged anionic polyacrylamides and with high molecular weight. The cationic and non-ionic polymers flocculated both minerals. In minerals mixtures, there appeared to be very little selectivity unless a combination of dispersant and electrolyte was used. The effect of dissolved minerals species, such as Cu, Fe, and Ni on flocculation of chalcopyrite, pentlandite, millerite, pyrrhotite, and covellite was studied by Acar and Somasundaran (SME-AIME, 1985). Reagents There were some major advances made in reagent development for the minerals processing industry. Cyanamid introduced several classes of collectors, one of which - the diaryl monothiophosphates as acid circuit col¬lectors of sulfides and oxidesulfide ores - was commercialized in 1985. The monothiophosphates are more stable and powerful collectors than the xanthates and dithiophosphates. Hydrolyzed dithiophosphate containing 80% monothio and 20% dithiophosphate was found to give optimum recovery of copper from crude cementation precipitate and separation of Cu and Ni sulfides from matte (Akimova et al., Obogashch, Tonkov, Rud, OTR, 1985). A new class of O-alkyl-Nallyl

Jan 9, 1986

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

2.1 INTRODUCTION When total extraction of an opening of sufficient size is reached in a horizontal coal seam, the roof strata in the overburden deform continuously to reach a new equilibrium condition. The severity of deformation decreases upward toward the surface. As the downward saggings of the strata propagate and reach the surface, there will be a depression zone on the surface directly above, but extending beyond the edges of the underground opening. This is the surface subsidence basin or surface subsidence trough. The surface subsidence basin is circular in plan view, if the coal seam is horizontal and the mined-out opening is square in shape. But it is rectangular with rounded corners or elliptical if the coal seam is horizontal and the mined-out opening is a long- and thin rectangle or a short-rectangular, respectively (Fig. 2.1). Most underground openings (e.g., longwall panel) assume rectangular shape when total extraction has been completed. Theoretically the edges of the subsidence basin are the points of zero subsidence. But it is difficult to exactly locate the points of zero subsidence. Therefore in practice the points with vertical subsidence of 0.4 in. (10 mm) are used. The final subsidence basin is that which exists long after the mining has been completed, because its magnitude and shape are quite different from the dynamic subsidence basin formed while the face is moving. 2.2 CHARACTERISTICS AND TYPES OF DEFORMATION IN THE FINAL SUBSIDENCE BASIN For a horizontal coal seam, every point in the subsidence basin moves toward the center of the basin. Subsidence is maximum at the center of the basin. Any cross-section that passes through the point of maximum subsidence and either parallel to AB or CD line (Fig. 2.1) is a major cross-section along which principal directions of surface movements occur. However among those infinite numbers of major cross-sections, two specific ones are of special significance, not only because the magnitudes of surface movements are the largest, but also because they are the most easily identifiable directions, i.e., one that is parallel to the faceline at the center of the basin (CD in Fig. 2.1) and&apos; the other is that perpendicular to the faceline but parallel to the diction of face advance (AB in Fig. 2.1). Nearly all the subsidence data obtained in the US have been derived from these two cross-sections, although some cross- sections parallel to CD but near the edges of the panel have also been included. In addition to moving horizontally toward the center of the basin, every point in the basin also subsides vertically. The magnitude of subsidence increases toward the center of the basin. Therefore surface subsidence is a three-dimensional problem and should be treated so in all cases. On all the major cross-sections, only principal subsidence and principal displacement occur. Since subsidence and displacement vary continuously in every major cross-section, three additional deformation components are de- rived, i.e., slope, curvature, and strain. On all other non-major cross-sections on the other hand the five components are accompanied by two additional components, i.e., twisting and shear strain. The seven components of the surface movement are defined as follows (Fig. 2.2): 1. Subsidence, S. On any cross-section, the vertical component of the surface movement vector is called surface subsidence. It generally points downward. But sometimes it points upward in areas ahead of the faceline or beyond the edges of the opening. In such cases it is a surface heave which is usually less than 6 in. 2. Displacement, U. On any cross-section, the horizontal component of the surface movement vector is called surface horizontal displacement. It generally points toward the center of the subsidence basin. But in steep terrain, it moves along the downdip direction 3. Slope, i. On any cross-section, the difference in surface subsidence between the two end points of a line section divided by the horizontal distance between the two points is called the surface slope of the section. 4. Curvature, K. On any cross-section, the difference in surface slope between two adjacent line sections divided by the average length of the two line sections is called the surface curvature of those two line sections. There are two types of curvature: con- vex or positive curvature and concave or negative curvature. 5. Horizontal strain, e. On any cross-section, the difference in horizontal displacement between any two points divided by the distance between the two points is called horizontal strain. If the distance between the two points is lengthening, it is tensile strain with positive sign. Conversely, if it is shortening, it is compressive strain with negative sign 6. Twisting, T. On the surface of the subsidence basin, the difference in slope between two parallel line sections divided by the distance between the two line sections is called twisting. 7. Shear strain, y. Shear strain is the changes in internal angles of a square on the surface of the subsidence basin or on any major cross-section. It is the summation of the differences in incremental (or decremental) lengths between the two opposite sides divided by the original distance between the two opposite sides. More precisely, the surface deformation indices (i.e., slope, strain, curvature, twisting and shear) are defined by derivatives of surface movement components. For simplicity, the x- and y-axes of the cartesian coordinate system are set to be parallel and perpendicular to the cross-section of interest, respectively. In such a coordinate system, slope and curvature along x direction are the first and the second derivatives of the vertical components (S) of surface movement with respect to x, respectively, or i, = ds/dx and kx = d2s/dx2. Horizontal strain along x direction is the first derivative of the component along x direction of the horizontal displacement,

Jan 1, 1992

By George B. Rice

In a recent speech in Pittsburgh, Dr. George Keyworth, the President&apos;s Science Advisor, made a statement which I believe deserves our very careful consideration. Dr. Keyworth said that there is no energy crisis. The crisis, he explained, is simply that people refuse to accept the solution. The solution which Dr. Keyworth has in mind is increased utilization of our abundant supplies of solid fuels and, in particular, uranium. I share his view concerning the solution to our energy needs. The use of uranium fuel is a safe, clean, and dependable means to generate our electric power. It is time that we addressed the real energy crisis: the refusal to accept the nuclear solution. The reason for the refusal is not difficult to find. It is nihilistic thinking about risk. Under this thinking, we assume the worst possible case and act accordingly, simply because we cannot prove to a total certainty that nuclear energy is perfectly safe. If this absolutist approach were generally applied throughout our society, there is no doubt all of us would soon be sitting around our campfires fearfully holding the wild animals at bay with our trusty spears. Today I am here to enlist your support in reversing the regulatory trend that threatens the very extistence of the nuclear power industry. As distinguished scientists, engineers and businessmen, you can use your influence to help bring rational regulation to the industry. Our industry supports strong safety and environmental protection programs. We understand the need for and do not object to reasonable regulation. Many anti-pollution measures can be practical to implement, cost effective and highly successful in minimizing environmental impacts. However, it is a fact of life that in the field of health and safety regulation, the law of diminishing returns operates with a vengeance. Absolute or near-absolute safety is impossible and any attempt to achieve it is intolerably costly. Fixation on absolute safety is particularly acute in the regulation of the nuclear power industry. Government Agencies, overly anxious to allay the irrational fears of those opposed to nuclear power, are literally regulating the industry to death - exactly the result sought by the anti-nuclear groups. Dr. Robert L. DuPont wrote in a recent issue of [Business Week]: "The nuclear power industry has been virtually stopped in the U.S. [because of fear]. This is true despite the fact that for more than 20 years the commercial nuclear industry has operated under unprecedented public health scrutiny and that to date there have been no radiation-related injuries, let alone deaths, suffered by any member of the public."1 I believe a useful way to convey the nature of the problem faced by the nuclear industry is to review an example of [unreasonable] regulation. While the example relates to our domestic industry, I am certain there are similar situations in other countries. For the example I will use the Nuclear Regulatory Commission&apos;s recently issued regulations governing the stabilization of uranium mill tailings.2 These regulations, known as the Uranium Mill Licensing Requirements, specify, among other things, that radon emanation from uranium mill tailings be limited to no more than 2 pCi/m2-sec. First, one must understand that this standard will have virtually no impact on the total amount of radon to which the public is exposed. Radon emitted from even completely unstabilized tailings piles is a tiny fraction--much less than 1%--of the amount of radon released from natural soils in the United States.3 In fact, it is far outweighed by natural variations in the background flux. For example, changes in the level of the Great Salt Lake in recent years have had [eight times] as much effect on the amount of radon released into the Salt Lake City regional air than the annual release from the Vitro Mill tailings pile located in that city.4 Nevertheless, NRC claims that the standard is required to protect the public. The Commission admits, however, that there are no studies which establish that exposure to radon at the low levels associated with uranium mill tailings will result in any adverse health effects.5 In the absence of actual evidence, the Commission assumes that some such effects will occur on the basis of the linear, non-threshold model.6 Employing this model, NRC calculates that the maximum hypothetical risk for the average member of the population is only about 1 in 70,000,000 from the radon that would be emitted from [three times] the number of mills now in existence, even if the tailings produced through the year 2000 are left unstabilized.7 NRC has elsewhere explained that this level of risk would be equivalent to the risk posed by "a few puffs on a cigarette, a few sips of wine, driving the family car about 6 blocks, flying about 2 miles, canoeing for 3 seconds, or being a man age 60 for 11 seconds." This level of risk is [de minimis] in comparison to other risks commonly and readily incurred in our society.9 Moreover, even this remote risk is overstated. A group of prominent health physicists, including experts from the Department of Energy, The Environmental Protection Agency, Britain, Canada and Germany recently published a study indicating that the risk to the public per unit exposure to radon can be no greater than one-third that suggested by the Commission, and [may in fact be zero].l0 Regulators routinely rationalize the need for their regulations. For example, NRC attempts to justify the radon flux standard because it is necessary to reduce the risk to someone who builds a house on top of a tailings pile. This possibility, however, is totally unrealistic because the Mill Tailings Act requires that stabilized tailings be transferred to

Jan 1, 1981

The structure of a mine ventilation network (M.V.N.) can be represented graphically using either the mine plan (map) itself or a number of other types of diagrams. In the U.S., the two most common approaches are the line and the schematic diagrams (see Figures 1 and 2). The purpose of this paper is to introduce another type of diagram, called the canonical diagram (6). The method of M.V.N. representation which uses canonical diagrams is used extensively in Europe, and especially in Poland, where it was developed. The canonical diagram is a noncalibrated topological image of a ventilation system. It gives a simple representation of the ventilation network, allows for the classification of currents within it and enables rapid computer analysis and computation, as well as the representation of the results. It is especially useful in studying and controlling the air flow, and it may be a life saving tool in conducting rescue operations during and after mine fires.

Jan 1, 1986

After World War I the character of my mining life changed completely. Before then adventure had been almost continuous but after the war there was lots of staying in one place, almost routine, between adventures. This was fortunate, as the life of a mining engineer is a wandering one at best, and it makes being married and raising a family a dubious enterprise. It would have been quite out of the question with the life I led before I got married at the end of the war The new sort of life made the "beaconing of adventure" intermittent. There were often long stays at home between wanderings which was fortunate as it changed the continuity of these memories. I must briefly summarize accounts of the more or less routine periods and concentrate on the occasional exciting episodes between. After a long visit with friends in Berkeley, Dorothy and I left for Arizona and three days at the Grand Canyon that were nearly too much for both of us. One beautiful day we started a short walk down the Bright Angel Trail. It was such a lovely bracing day that we kept on walking and enjoying the views until, just after noon, we reached the Colorado River. We were the only ones in sight so to enjoy the sunshine to the full we both had a good swim in the swiftly flowing river. So far, everything was wonderful. But when we started to climb back up the trail, rising nearly 6000 ft in ten miles we soon found that we had counted too much on our youth and endurance. We had to rest every few hundred feet and it seemed as though we would never reach the top. It was eight o&apos;clock in the evening when we finally staggered into our room and collapsed. On the way to the Canyon I had seen John Greenway and Dr. Ricketts in Santa Barbara and they had little idea what would happen to them or to me. Before resuming his position as general manager of Calumet and Arizona and New Cornelia, Greenway must recover from the effects of the gas he had suffered in the war. Dr. Ricketts

Jan 1, 1976