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By T. M. Gurr

It is estimated that in excess of one-half million chemicals are used throughout the American workplace. Hundreds of new chemicals are also being introduced into the workplace annually. Exposure to some of these chemicals can be harmful to workers and to the environment. The Occupational Safety and Health Administration (OSHA) estimates that approximately 25% of the U. S. labor force or approximately 25 million workers are exposed to one or more chemical hazards each year. OSHA has determined that this poses a serious problem for workers exposed to such chemicals. Chemical exposure may cause safety and health problems. Health problems can include a cause or contribution to heart ailments, kidney and lung damage, sterility, cancer, burns, and rashes. Safety hazards can include the potential to cause fires and explosions and other serious accidents.

Jan 1, 1989

By Yoshio Hiramatsu

In Toyoha mine near Sapporo, the ground temperature is very high, perhaps due to inflow of hot mineral water, the origin of which may be rock masses intruded by the igneous activity in the Tertiary period. The rock masses are found about 2 km east of the mine, their temperature being estimated at from 770 to 870 K at a depth of 3 km. In this mine several veins bearing zinc and lead ores have been mined down to the depth of 300 m from the level of the main entry, of which altitude is 551 m above the sea level. Formerly no attempt was made at development of the deeper part of the mine than the 350 m level from the main entry. Let us indicate hereafter the levels in this mine in such a way that the level 300 m deep from the main entry is denoted as 300 mL. Since 1974, however, the 450 mL of Tajima vein has been developed by deepening No. 5 Shaft to, and by driving drifts in the level. Much hot mineral water has been flowing into the drifts from rock. After twenty-eight months from the beginning of development, the total length of excavation amounted to about 1300 m. The success in development so far may be attributed to cooling rock and air with chilled water and to adopting heat-resisting explosives and detonators. This cooling costed very much and for further development in this level a more effective and economical cooling is desired if possible. To obtain fundamental data for designing an economical cooling, the authors investigated, as a preliminary study, the heat balance in the main drift of 450 mL, by measuring the temperatures of air, rock, hot mineral water, the rates of flow of air and water and so on, in August 1976. They are now carrying out continual measurements of the variations in rock temperature, air temperature and humidity with time. The present paper describes the details of the preliminary study.

Jan 1, 1980

By Dennis C. Drehmel

Because of their relatively low cost, carbonate rocks are desirable in abatement of air pollution by acid gases. Although many processes and types of equipment have been proposed to control or prevent the emission of acid gases, this paper considers only three: dry-limestone injection, wet-limestone scrubbing, and chemically active fluid beds. For the dry-limestone-injection process, surface area-especially from pores in the 0. 2- to 0.3-micron range-is one of the important parameters which will discriminate between less and more reactive carbonate rocks. Marls, chalks, oolitic calcites, and other fine- grained limestones show larger-than-average surface areas and better- than-average removal efficiencies. Inert chemical impurities such as silica detract from reactivity. A dolomite is not necessarily less re- active than a calcite. For the wet-limestone-scrubbing process, dissolution rate of the carbonate rock controls the differences in stone reactivity. In this process the dolomites are less reactive than the calcites. In addition, more than 90 percent of the dolomitic impurity in Fredonia white lime- stone is inert during limestone scrubbing. Dissolution rate is also a function of particle size for large-grained carbonate rocks. Fine grinding of such rocks will increase the dissolution rate to that of a fine-grained rock. Hence the requirement of high dissolution rates may be met by some grinding of fine-grained material (e. g., marl, chalk, or other limestone) or by fine grinding of coarser grained material. For chemically active fluid beds, chalks have the best capacity to absorb both SO2 and H2S. However, most chalks are probably unsuitable for fluid beds because of high attrition rates. Because dolomites are generally more reactive than calcites with both SO2 and H2S, a dolomite would be the feed material of choice for a chemically active fluid bed.

Jan 1, 1974

By Daryl L. Gusey, John T. Neubert, Matthew A. Sares

The Colorado Geological Survey completed an inventory of environmental degradation associated with abandoned and inactive mines on National Forest System lands in Colorado. In the course of the inventory, areas with naturally occurring acid rock drainage were also noted. Approximately 18,000 abandoned mine- related features were inventoried, including about 900 features that are considered significant enough environmental problems to warrant further investigation. Water quality data, such as pH and conductivity were gathered at all features where water was present, such as draining adits, seepage at the toe of dumps and tailings, and standing water in shafts. Samples were taken where field tests indicated low pH andlor high conductivity, including several areas with naturally occurring acid rock drainage. Samples were analyzed for dissolved and total metals, and for selected anions. All mine locations and data collected by the field geologists were entered on field forms and, subsequently, into a computer database and GIS format. With the information provided by the inventory, the Forest Service, in cooperation with other agencies, has been able to prioritize abandoned mines for reclamation. In most cases, cleanup is approached on a watershed basis. Mines in priority watersheds have been selected for reclamation first. Watersheds where studies prerequisite to cleanup are occurring include the upper Anirnas River, Willow Creek (tributary to the upper Rio Grande), Chalk Creek (tributary to the upper Arkansas River), the Uncompahgre River, and the Alamosa River. During the inventory, evidence of naturally occurring water quality degradation was found in areas where little or no evidence of mining activity exists. These areas include the upper Alamosa River, the Middle Fork of Mineral Creek, Peekaboo Gulch, and Handcart Gulch. Water from these natural sources has been found to significantly exceed Colorado water quality standards for several metals.

Jan 1, 2000

By Kaye P. Strong, Desmond M. Levins, Anthony G. Fane

1. INTRODUCTION The safe disposal of tailings is the most important environmental question facing the uranium mining industry today. This is because tailings present a major long term radiological hazard as they contain about 71% of the radioactivity originally in the ore. The magnitude of the problem can be appreciated by considering the quantity of tailings involved. For example, projections of milling programs in Australia indicate that there will be 100 million tonnes of tailings produced by the year 2000 (Levins 1980). The United States currently has in excess of 100 million tonnes and by the year 2000 will have between 900 and 1700 million tonnes (Landa 1980). Present options for tailings rehabilitation include leaving them above ground, returning them to the mine or placing them in specially excavated pits. In any event, the tailings will be covered with earth and revegetation attempted. This will remove the problems of airborne radioactive dust and water erosion of the tailings, at least in the short term, but diffusion of radon-222* from the tailings may still occur. The Atomic Energy Control Board of Canada (1981) has proposed a maximum allowable radon flux from rehabilitated tailings of 0.074-0.37 Bq m -2s-1(2-10 pCi M-2 s-1); the exact level is to be determined "after discussion with other regulatory agencies and the industry". The United States Nuclear Regulatory Commission (USNRC 1980) has been more restrictive in recommending a maximum flux of 0.074 Bq m -2s-1 (2 pCi m-2s-1). As a guideline they also suggested a minimum depth of covering material of 3 m to achieve this surface flux for tailings typically found in the western milling regions of the United States. The design of rehabilitation schemes is aided by a knowledge of radon transport through tailings piles. In this paper we present the results of a theoretical analysis and experimental study of radon diffusion through selected Australian tailings and cover material. The minimum cover criteria of 3 m is reexamined in the light of these findings. [ ]

Jan 1, 1981

By D. Craig Camp

Microtunneling has successfully completed both horizontal and vertical curves. This paper covers the historical development of curved microtunneling and a description of one microtunneling project. The completed microtunnel is used for electrical transmission in Japan. The crossing had several concerns including right of way, social disruption, obstructions, the cost of intermediate shafts, and political restrains. In order for this drive to meet all of the imposed restrictions, four horizontal curves and one vertical curve were planned and executed in accordance with the design. Iseki Poly-Tech of Tokyo, Japan designed and built the microtunneling machine to meet the project requirements. Curved microtunneling has been successfully used on fourteen projects in Japan. The reason for a curve has been that the project could not be rerouted, short straight drives could not be used to negotiate the curve, or the project’s social and environmental conditions required a curved tunnel. The following table (Table 1) includes summary information on 14 curved microtunnling projects that have been successfully completed in Japan. The first column is a reference number. Columns two through four include basic project information. The fifth column is the total project distance completed by microtunneling. The sixth column is the project’s microtunneling duration. The seventh column is the machine type and size. All of the machines listed are manufactured by Iseki Poly-Tech of Tokyo, Japan. The size is the internal concrete pipe diameter; all of the projects listed were completed with Japanese standard concrete pipe. The eighth column contains a general description of the soil. The soil type and blow counts are approximately equal to ASTM D 2487 standards. The ninth column lists the radius of the curve and the span distance or the distance microtunneled that included the curve. The radius of a vertical curve is denoted with a “VR”, a span with both a left and right hand curve is denoted with a “S”. Other significant first events are also noted in this column. The first curved microtunneling project was completed in 1982 using a conventional microtunneling machine with standard Japanese concrete pipe and a very long radius curve while maintaining grade for the gravity sewer. The second curved microtunneling project included multiple radii curves, all in the same direction, on a single drive. In 1989, on the fifth curved microtunneling project, a “S” curve was successfully negotiated. On the seventh curved microtunneling project, completed in1995, a tight radius curve was negotiated. In 1996, the eighth project included a vertical curve. The thirteenth curved microtunneling project, completed in 1997, was the first project to utilize a microtunneling machine specifically designed to negotiate curves. The fourteenth curved microtunneling project was the accumulation of all

Jan 1, 2001

By Geno Saccomanno

INTRODUCTION Cancer of the lung in uranium miners has been reported by many authors. In fact, it has become a most popular subject for comment by environmentalists, health physicists, and newspaper writers. I believe it appropriate for me to discuss cancer of the lung in uranium miners in a general way commenting briefly on etiology, incidence, tumor cell types, and particularly, tumor development and treatment. Cytological development of cancer in its incipient stages, particularly the in situ stage, relates to potential cure with photoradiation, early diagnosis, and treatment. Our observations of the cytological response to this modality of diagnosis and treatment will be discussed briefly since this area will also be covered by Doctor Balchum. The cause of lung cancer in uranium miners is primarily due to two carcinogens; cigarette smoking and radon daughter radiation. Cigarette smoking has continued at the same intensity over time among uranium miners; about 60% of the miners are cigarette smokers and 40% are non-smokers. Radon daughter exposure to the uranium miner has varied from mine to mine, but over the last 20 years has been reduced to a minor fraction (.3 WL) of the level that prevailed in many of the mines during the 1950-1960 era when many of the miners were exposed to more than 10 WLM. Sputum samples have been examined on as many uranium miners as responded on the Colorado Plateau since 1956. Autopsy studies were done whenever this was permissible. In some instances, only tissue from a biopsy of a node or lung was available for study. Smoking histories were also taken. Approximately 200,000 sputum samples were examined and histological examinations of lung lesions were made from 312 cases. METHODS The method of sputum cytological collection and preparation was reported previously. I The lungs were fixed with formalin and prepared for sectioning by Dr. Oscar Auerbach with his block-section method. RESULTS Three-hundred-twelve lung cancers from uranium miners were examined. The tumor types and the age at death for each type, smokers and non-smokers, are given in Table #1. The incidence of the tumors in the smokers and non-smokers is given in Table #2. The incidence of small cell carcinoma of the lung has decreased from an incidence of 76% of all the lung cancers found in uranium miners to 22% of these lesions (Figure #1). The decrease in incidence of this tumor is probably due to decreased exposure to radiation in the mines.

Jan 1, 1981

By Robert S. Ondrey, Robert A. Haney, Kenneth G. Fields

As part of an MSHA program to assess the effectiveness of dust control parameters for longwall mining operations, respirable dust studies were conducted on six longwall sections. The purpose of these studies was to evaluate the influence of airflow and production on longwall dust control. The sections were sampled for 3 to 35 shifts. In addition to dust, ventilation and production measurements, other dust control and operational parameters were measured. The water spray system at each operation conformed with generally recommended practices. Therefore, improvements to the dust control system would be most appropriately achieved through improvements to ventilation along the face. Two methods of assessing the influence of ventilation and production were used. For two of the six mines where extensive sampling (22 and 35 shifts) was conducted, multiple linear regressions were used to relate the dust concentration versus airflow and production data. For these two mines, statistically significant correlations existed between concentration and both production and airflow. The multiple regressions fit to the data indicated that for every 0.47 m3/s (1,000 cfm) increase in airflow, there would be approximately 0.04 to 0.07 mg/m3 reduction in dust concentration; and, for every 1,000 ton increase in production, there would be approximately 0.15 to 0.50 mg/m3 increase in dust concentration. For the four mines with limited data (3 to 10 shifts), as well as for the two mines with extensive sampling, an average ratio of airflow per ton of coal mined was calculated by proportioning the airflow to production and the designated occupation personal respirable dust exposure to a 2.0 mg/m3 concentration. The airflow-to-tons ratio required to maintain a 2.0 mg/m3 dust concentration ranged from 0.0038 0.0071 m3/s per ton (8 to 15 cfm/ton). Both of these data treatments were used to calculate airflow requirements based on normal production rates. For the two mines where both the regression and airflow-to-tons ratio were calculated, results from the two methods agreed within 25 percent.

Jan 1, 1993

By G. H. Lewis, C. L. Krcil, N. S. Harding, D. E. Havekotte

INTRODUCTION Limestone injection work was completed in a 440-kW (1.5-million Btu per hour) pilot-scale combustor in preparation for a 50,000-kg/h (110,000-lb per hour) industrial steam boiler limestone injection test program. The main objectives were to: (1) identify the important variables that affect sulfur capture, (2) determine the maximum SO2 removal, and (3) determine the effect of limestone addition on furnace operability and heat transfer. A more detailed report is given by Lewis et al. (1985). The test program was divided into two phases. The objectives of Phase I were to determine the important variables that affect SO2 reduction and to investigate the effect of limestone addition on combustor operation and heat transfer surfaces. The objective of Phase II was to determine, using only the important variables identified during Phase I, the conditions that resulted in the greatest sulfur dioxide reduction. Phase I Test program Using one limestone, five variables were identified as having an effect on SO2 reduction. These are noted with their respective ranges: heat release rate [103 to 166 kW/m3 (10,000 to 16,000 Btu per hour-cu ft)], Ca/S molar ratio (0 to 3), flue gas oxygen concentration (3% to 5%), additive particle size [90% -150 µm (-100 mesh) and 90% -45 µm (-325 mesh)], and burner stoichiometry (SR = 0.75 and >1.15). A 2.3% sulfur northern West Virginia coal, pulverized to a nominal grind of 70% -75 µm (-200 mesh), was burned for the tests. The limestone used was obtained from a Maysville, KY, quarry and contained 51.75% (wt) CaO. An 11-run statistically designed program (plus three duplicates) was used to screen the five variables. The effect of limestone injection on the combustor heat transfer surfaces was determined by comparing the heat transfer rates through a slag panel and fouling probes during periods with and without limestone injection. Combustor operation was determined by noting any operating problems that occurred during the tests. Test procedure After furnace wall temperatures had stabilized at operating conditions, heat transfer surfaces (slag panel and fouling probes) and the convection section were blown clean, and a four-hour test was begun. The

Jan 1, 1987

By Nathaniel Arbiter

In attempting to assess the contributions of Antoine Gaudin to the profession which he illuminated for almost a half-century, we will need to examine a very broad canvas. He was active in three significant areas: as a teacher; in research, both through his own endeavors and those of his students; and as a consultant to the mining industry and to the Government. Beyond these specific contributions, there was the major personal influence he had on scores of students, friends, and colleagues in the profession. If a single measure of the man's contribution is to be found, it will be the extent and direction in which he influenced the practice of his profession. To find this we should examine the state of miner- al processing when he began his activities in the 1920's, the progress which has taken place over the past half-century, and the part his activities played in this advance. However, there is a provocative and broader examination which I have chosen to make instead. This is to examine the past century in mineral processing through the lives of three men who, by common agreement, stand on the heights, both in teaching and in their contributions to industry: Robert H. Richards, Arthur F. Taggart, and the man whose memory we honor this evening, Antoine M. Gaudin. Their careers, by coincidence, cover just a century. This is also AIME's first century, and the first century of mineral industry education in the United States. In fact, mineral processing itself on any significant scale in the country encompasses only a century and a quarter. BEGINNINGS OF PRACTICE IN THE U.S. Before the 1840qs, U.S. mining, except for coal and iron ore, was on a small scale and was confined to the eastern states, with processing practically nonexistent. The 1840's saw the beginning of Michigan native copper production, including ore dressing; the 18501s, iron ore production in Minnesota; and the 18601s, lead production and processing in Missouri. But the most explosive event was the California gold rush after 1848, which not only brought tens-of-thousands of fortune hunters to the West, but also catalyzed broad mining activities and processing within the following decades. This was not only in Calif-

Jan 1, 1976

By R. C. Dunne, C. T. O'Connor

Flotation practice on eighteen South African flotation plants is described. The plants are categorized as those treating reclaimed tailings, those treating material which has already been subjected to cyanidation or uranium leaching, and those treating milled ore. The similarities and differences are highlighted.

Jan 1, 1998

By Nora M. Hutt, Kevin A. Morin

There is currently some pessimism over mixing of net-acid-neutralizing (NAN) and net-acid-generating (NAG) rock to obtain indefinite near-neutral seepage from mined-rock piles. This is due in large part to the lack of well- documented, successful cases of blending and layering, and to the knowledge of unsuccessful attempts. Past work often defined a potentially successful mix in terms of the ratio of net-acid-neutralizing rock to net-acid-generating rock. For example, one case study indicated the bulk pile-wide ratio was approximately 3: 1. Since this exceeded a common ratio used in acid-base accounting, no acidic drainage was predicted. However, acidic drainage appeared within two years. A large part of the ambiguity in mixing arises from attempts to predict success based on a ratio. This paper looks in detail at simple discrete-zone mixing, where at least one truckload of NAG rock is placed in a particular location with no further rehandling or dozing. The lack of acidic drainage in this scenario is dependent on the intervening distance between the discrete NAG zones, along flowpaths occupied by NAN rock. Calculations show that the bulk mixing ratio of a mined-rock pile is not an accurate indication of whether near-neutral drainage can be maintained. For example, a pile with a bulk ratio around 300: 1 could still release some acidic drainage. Calculations also show that the minimum separation distance of the NAG zones (L) can be so great, even with typical NAG and NAN rock, that the mixed pile could safely contain only a few percent of NAG rock, which would not be sufficient for many minesites with NAG rock. The comparison to a more elaborate, computer-based statistical model shows that the simple discrete-zone approach will provide a reliable yes-no indication of whether any acidic drainage will leave a pile. However, predictions of whether combined downstream drainages will be acidic depend on numerous site-specific physical and geochemical factors within and below a pile that cannot be modelled in a general way, like the number of flowpaths and the nature of their intersections.

Jan 1, 2000

By C. Timothy Shaw

Traditionally, only the large mining companies have maintained specialist departments in such areas as Rock Mechanics, Ventilation and Safety. To the small companies this has been a luxury that they could ill afford. Any work required by such companies in these areas, more complex than could be handled by the existing staff, was done by consultants. This situation is changing though and there is a need arising for many specialist departments. These changes are partly being brought about by the effects of inflation as the ever increasing costs are causing more and more operators to increase the size of their operations in search of economies of scale. In addition though the plethora of new laws and regulations are creating a need for many more specialists in all areas of mining in order to ensure compliance. The abovementioned factors, added to the existing Pattern of mines endeavoring to improve the working environment for their labor force, both for reasons of practical labor relations and also due to further legislative pressures, have thus created a climate where, in the near future, departments such as Rock Mechanics, Safety, Ventilation, Environmental Engineering and Subsidence Control will be commonplace in mining companies. It will no longer be practical to function without such services. Many mining companies already maintain such departments and this has particularly been true of the big mining groups of South Africa. From the experience gained by many of these large companies with specialist departments, it is clear that the maintenance of a cadre of experienced, competent professionals in such a department has not always been easy. It would seem from the experience gained that one can generalise and state that graduate mining engineers tend not to view specilisation as an optimum direction for their career development. It is of course true that many professionals, especially those with higher than a bachelors degree, do view these areas as valid career options, but even here experience shows that wastage is high. The time therefore seems to be ripe to take a look at this area in some detail to see whether reasons for the problems can be isolated. Working from that some suggestions can be made as to directions in which improvements might be made. If the challenge of the demands of the new regulations are to be met then such improvements must be made.

Jan 1, 1980

By Qing Wang, Xiaochuan Xu, Jianping Liu, Xiaowei Gu, Qingyu Zhu

"The ecological costs related to the various optimized production schemes were calculated based on the designed ultimate pit. Moreover, the influence of the ecological costs on the selection of production schemes was discussed. In one designed pit, a series of geologically optimum pushbacks with sufficiently small increment were produced using the floating cone method founded on the principle of the highest metal content. Then all the pushbacks were reordered by the dynamic network diagram. The production scheme with the maximum NPV route was considered as the optimum one. The ecological impacts produced by mining were quantified and the ecological cost calculation models, which contain the direct eco-value loss, the indirect eco-value loss, the eco-restoration cost and the carbon emission cost were proposed. In one big open pit mine case, various production schemes were optimized and the one with maximum NPV was selected without taking into account the eco-costs. The scheme with the maximum comprehensive profit was obtained by calculating the eco-cost of each scheme. The results showed that the best scheme considered with the eco-cost was not the scheme with the maximum NPV. Therefore, the eco-cost presents the effect on the selection of the best production scheme.Introduction Optimizing production scheme is to determine the mining quantities of ore and rock, the pushing position of stope each year, and maximize the NPV of mine. In the theory, production scheming optimization has gone through trial and error (Pana and Carlson 1966), linear programming method (Johnson 1968), mixed integer programming (Gershon 1983), integer mapping (Kim and Cai 1990), dynamic programming et al (Gu et al 2014). In recent years, the study on production scheduling optimization has been focused on two aspects. On the one hand, the study is to solve the investment risk caused by the uncertainties of economic and geological environment (Ramazan and Dimitrakopoulos 2013, Marcotte and Caron 2010, Lamghari and Dimitrakopoulos 2012, Godoy and Dimitrakopoulos 2004, Benndorf and Shishvan 2014). On the other hand, the emphasis of the study was on reducing the problems for the optimization algorithm, to make it more efficient and practical (Cullenbine et al 2011, Shishvan and Sattarvand 2015, Askari-Nasab et al 2011, Nasab et al 2010). However, different production schemes cause different damage of mine land and pollutant emission, thus triggering environment problem. With the improvement of people’s consciousness of environment protection, the environmental issue of mining has been attracting more and more attention."

Jan 1, 2017

By B. F. Buie

In South Carolina and Georgia an area about 20 miles wide situated near the inner margin of the Coastal Plain and extending from the vicinity of Columbia, S.C. southwestward about 180 miles to the vicinity of Macon, Georgia is the principal kaolin-producing area of the world. It is especially important as the world's major source of clay used for paper coating. Essentially all of the land known or likely to be productive of quality kaolin in this area is now owned or controlled by producing companies. The least-fully developed portion is that in the vicinity of Wrens, Georgia which has been explored and developed since 1961. For the two decades following the end of world war II, demand for kaolin increased at approximately twice the rate for other industrial minerals. From 1945 to 1965 production increased four-fold. Since 1965 the rate of increase has been less, but the outlook now is that production and demand will double at least once again before the year 2000. A substantial part of this increased demand has come, and will continue to come, from industrial development, especially in the paper industry, outside the United States. The general effect, in addition to a continuing increase in production in the U.S., will be to cause: 1. Intensive research for development of more effective and more economical methods of beneficiation; 2. Concerted research effort to find an economical way of modifying high-viscosity kaolin so that it can be used for paper coating; 3. More active exploration in the U.S. and overseas, especially for deposits to supply the foreign markets; 4. More intensive study of the geological factors responsible for the accumulation of commercial deposits of kaolin; 5. Some modest rise in price, relative to the cost of other industrial minerals. The effect on kaolin producing region of Georgia and South Carolina will be to cause: 1. Working of progressively lower-grade deposits; 2. An increase in the acceptable thickness of overburden; 3. Mining of deposits farther down-dip, the use of which is now inhibited by large volumes of groundwater; 4. Increased threat of invasion of the kaolin in industry's market by substitute materials; 5. A substantial increase in concern over environmental factors; 6. More attention to be paid to the large opportunity offered for mining of silica sand and other co-products.

Jan 1, 1972

By G. Meiers, M. O’Kane

Dry cover systems as a closure option for management and decommissioning of waste rock and tailings is a common prevention and control technique used at numerous sites around the world. Numerous site-specific factors control the long-term performance of dry cover systems. Site-specific climate conditions are one of the key factors to consider when determining the objectives of a dry cover system because these conditions will significantly influence long-term performance. There are advantages and disadvantages of characterizing the site on an annual basis as generally a “dry” site (annual potential evaporation greatly exceeds annual precipitation), or generally a “wet” site (annual precipitation meets or exceeds annual potential evaporation). The field performance monitoring data and discussion presented herein illustrates the caution that is required when using these “annual” criteria for characterizing site climate conditions. Numerous sites exist where precipitation exceeds potential evaporation on an annual basis; however, the site typically experiences hot, dry summer months where evaporation greatly exceeds rainfall. These dry summer conditions have a strong influence on long-term performance. In contrast, sites where potential evaporation exceeds precipitation on annual basis, typically experience periods of the year when a moisture surplus occurs, which also impacts on long-term performance. This paper uses soil-atmosphere cover design modelling and field performance monitoring from sites in Canada, Australia, and the United States to demonstrate the importance of considering site-specific climate conditions when predicting long-term cover system performance.

Jan 1, 2003

By Kegomoditswe Koitsiwe, Tsuyoshi Adachi

"This paper characterizes quarterly LME copper price fundamentals from 1995 to 2011 by analyzing the transformation of the market mechanism based on structural change perspective. Using chow test for structural change based on the least square multiple regression, we divide the price fluctuation into: Stable price period (1995Q3-1999Q2), Low stable price period (1999Q3 – 2003Q3) and Price fluctuation period (2003Q4 – 2011Q2). The results show the existence of structural breaks disproves the investigation of the full sample period as a whole. In different structural breakpoints the main drivers of copper prices changes and their impact are significantly different. Moreover, the paper examines the role of speculation in copper price fluctuations.Introduction The rise in commodities price volatility and financial and economic crisis have led to questions over the organisation of futures and physical commodities markets. Spikes in commodity prices and volatility have coincided with a surge in financial speculators in the commodity markets inspiring a polarised and hotly debate among academics and practitioners about the role of investors in the development of physical markets. In his seminal work Kaldor (1939) focused primarily on whether speculative activity in the futures markets reduces the variance of commodity spot prices. Yet, part of the literature finds that the introduction of futures contracts destabilizes the spot market. IMF (2006) studied commodities boom and its causes concluding that there is little support for the hypothesis that speculative activity affects either price levels over the long run or price swings in the short-run. The impact of speculative activity on commodity prices remains a highly contentious topic. Other market analysts take the view that the supply and demand for physical commodities remain the major determinants of market trends (Krugman 2008). It is the aim of this study to contribute to the literature by examining the drivers of copper price changes from a structural change perspective. In this context we are attempting to answer to: What are the main drivers leading to copper price fluctuations? Are these factors having the same effect in different periods or not? It is meaningful to understand drivers of copper prices and thereby, their fluctuations because it will help developing countries depending on copper export to anticipate market situation and avoid bad economic development challenges that can result from price fluctuations. Moreover, this can ensure sustainable mineral supply."

Jan 1, 2017

By Finn E. Bronner

HISTORICAL PERSPECTIVE "Blessed be the Lord my strength, which teacheth my hands to war and my fingers to fight." Thus sang David three thousand years ago, in tacit acceptance of the condition of war, and in praise of the exceptional military skills with which this warrior king of Israel was endowed. He had cause to exult, for he had consolidated King Saul's conquests and added new ones of his own, not least of which was the capture of Jerusalem. David revealed in this operation that his mastery of the military arts embraced not only the weaponry and tactics of his day, but also strategy and that oldest of intelligence techniques: spies. The Jebusites, who built Jerusalem, had encompassed the city with the first of its many walls, but had neglected to incorporate the sole reliable water supply within its perimeter. This was Ain Gihon, today called the Fountain of the Virgin, which bubbled out on the east slope of Mount Ophel, one of the ridges on which Jerusalem was built, and drained eastward into the Kidron Valley. Water was brought into the city in the traditional manner: by women descending the stony trail outside the wall to fill their jars at the spring. But this essential daily activity was vulnerable to interruption by a hostile force outside the walls. To remedy this weakness, the Jebusites had driven a gallery from the spring a short distance into the water-bearing limestone under the city, and there cut a small collecting basin in the rock, a common way to develop springs throughout this arid region. But then the Jebusites dug a small vertical shaft from the roof of the gallery above the cistern upward about 15 m. From the upper end of this shaft, they constructed a narrow inclined tunnel with rock-cut steps leading up to the city streets. Thus the water supply could be reached even in time of siege.

Jan 1, 1979

By Charles E. Melbye

INTRODUCTION In a discussion of South American exploration, it is difficult to know how much area to cover, as there has been such intense exploration for many years in all of the South American countries. Therefore, I have decided to discuss only Argentina, Bolivia and Peru in this paper, since I am most familiar with these three countries. This familiarity has been gained during my last 12 years of nearly continual exploration and mine development. Furthermore, these three countries form a contiguous block straddling the Andes Mountain chain for 2,200 miles in length N-S. Although Chile is part of this block, I excluded that country because it has had the longest recent history in South American exploration, and it is now in a mature stage where new important mines are being placed in production every year. Exploration must progress a lot for the other three countries to attain the stature of Chile. However, major exploration successes such as Yavacocha and Pieriva in Peru, Kori Khollu in Bolivia and Bajo Alumbrera, Agua Rica and Cerro Vanguardia in Argentina certainly indicates that these countries are rapidly accelerating in exploration successes and the resulting new mine developments. Also, by concentrating on three countries, I have avoided making this paper too lengthy. This paper will cover activities of both junior and senior mining companies, both of whom are making significant contributions to exploration. The junior companies often make the initial discovery, develop it further and then bring in a major company when large capital is required. Since most exploration is for gold and copper or combinations of these, most descriptions will cover these types. However, there are significant new exploration successes for zinc and for silver-lead-zinc, and they will be covered, as well. After descriptions of the various properties, there is included a discussion of the governmental policies of Argentina, Bolivia and Peru, as to how they are affecting exploration activities and budgets. Some of these problems could have a major negative affect on the future exploration plans of many companies. I have intended to cover what I think are significant exploration developments in each country, and if a company project is omitted, there was no intention to slight anyone. Since exploration results change monthly, there could be

Jan 1, 1998

By William H. Sutherland

INTRODUCTION Coal workers' pneumoconiosis and sili- cosis are only two of several diseases which are rlassed as pneumoconiosis. These are respiratory diseases caused by dusts which are inhaled and accumulated in the lungs. The individual particles of dust cannot be seen by the human eye. They are so small that they escape the natural cleansing mechanism of the nose and air passages and make their way down to the terminal air sacs of the lung where they injure the cells and cause the formation of scar tissue. Consequently, if there is exposure to high concentrations of dust over a period of time - usually, a number of years - the amount of scar tissue increases and begins to impair breathing. As a result, the miner develops shortness of breath, coughing and wheezing ad-if exposure continues - this progresses to permanent disability and frequently to death. Death is often due to pulmonary heart disease, the effect of stress on the heart 2s it tries to compensate for the weakened lungs. Specifically, silicosis is an occupational lung disease caused by the accumulation of free silica (quartz) in the lungs. Silicosis is considered the most important form of pneumoconiosis, not only because of its seriousness as a respiratory crippler, but also because of the large number of workers who risk contracting it in a variety of occupations. Quartz is one of the most common substances of the earth's crust, estimated at about 60 percent. Silicosis has been found in coal, metal and granite miners, as well as in other workers, such as sandblasters and pottery makers. Silicosis is also known to predispose the lung to tuberculosis and to increase the chances that a worker will contract chronic bronchitis and emphysema. The seriousness of silicosis was tragically brought to public attention about 50 years ago. During 1932-34, workers were involved in digging a tunnel through rock at Gauley Bridge, West Virginia. While their exposure time was relatively short, they developed silicosis because of the high concentrations of quartz. By 1936, 476 workers had died of silicosis and about 1500 were believed to have the disease (Washington Post, 1982). It is difficult to tell how many coal miners have silicosis. Because x-rays and breathing function tests do not show the difference the type of pneumoconiosis is generally diagnosed by the miner's work history. For example, if a worker

Jan 1, 1986