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By H. Wilcox, M. Prichard, Y. P. Chugh

Environmental considerations related to the disposal of coal combustion byproducts (CCBs) and the impacts of deforestation associated with the harvesting of timber for utilization as roof supports in mines should become more severe in the future, as landfill space and suitable timber reserves become more scarce. To help address these concerns, lightweight artificial supports, such as post and crib elements, that use large percentages of coal combustion byproducts as aggregate have been developed for use in underground mines. These structural products show equal or better engineering characteristics than timber, and they have the potential to replace timber support in underground mines. CCB-based ultralight structural material (ULSM) has also been developed and commercialized for use in the construction of ventilation stoppings in underground mines. The bulk densities of these blocks range from 0.40 to 0.64 g/cm3 (25 to 40 lb per cu ft) with more than 75% CCBs. Efforts are also given to develop and demonstrate large volume CCB-based subgrade improvement technique for road construction. Soil treated with SIUC fluidized-bed combustion (FBC) fly ash developed an immediate bearing value exceeding 25% with a swelling strain of less than I %, which is greater than untreated soils, and met Illinois Department of Transportation (IDOT) standard specifications. In this paper, development procedures, engineering characteristics and beneficial uses of CCB-based structural products are given.

Jan 1, 2002

By Clinton Strachan, Rob Dorey

10.1 INTRODUCTION This chapter presents considerations which should be applied to heap leach pad site selection, site evaluation, and design, relative to the geotechnics of the site and ore. 10.1.1 General Guidelines are presented covering the topics encountered in design and construction of heap leach faci1ities. Because geotechnical characteristics vary from site to site, not all geotechnical topics associated with a specific heap leach facility are presented, and there may be exceptions to some of these guidelines. The general features of a heap leach facility (from Chapter 1) to be discussed in this chapter are: • Leach pad (including leach pad foundation and liner); • Heap; • Solution storage faci1ities (for pregnant and barren process solutions) ; and • Solution collection facilities (which collect and convey solutions in the heap and convey them to solution storage facilities). These general features are illustrated in Figure 10.1. Liners for these facilities are discussed in Chapter 11. Solution application systems and the sizing aspects of solution storage facilities are discussed in Chapters 6, 7, and 12. The general features listed above are constructed with and overlie naturally occurring materials (such as ore, borrow soils, and subsurface soils and rock). These natural materials are relied upon to perform in an acceptable manner as a component of the leach facility (such as the liner, drain material, and foundation).

Jan 1, 1988

By S. E. Phillipson

Underground mine mapping is a critical component of understanding the controls on ground instability. Many relatively localized examples of ground failure are associated with geologic features, such as faults, joints, compaction zones, or sedimentological transition zones. In contrast, long-running, directional roof falls are associated with regionally directed horizontal stress fields, which are induced by tectonic plate interactions in the earth?s crust. When stress-related features are distinguished from geological features, underground mapping can be an effective method for inferring the direction of horizontal stress at individual mines. Comparisons with data compiled in the World Stress Map confirm that underground mapping can be a valid method for determining the orientation of maximum principal horizontal stress at a variety of scales, ranging from individual mines to an entire mining district or coal basin. Comparisons are presented between the maximum horizontal stress directions inferred by MSHA?s Roof Control Division through underground mapping and the azimuths of maximum horizontal stress in the World Stress Map database for North America?s Pennsylvanian-aged Appalachian, Illinois, Black Warrior, and Arkoma Basin coal fields. The comparison indicates that azimuths are similar for both data sets, even where variations in the direction of horizontal stress are present. It is interpreted that inconsistencies in direction are attributable to near-surface affects such as deeply incised stream valleys, or to fault zones that represent heterogeneities in the crust.

Jan 1, 2009

By Tsunenori Shibata, Kazunori Jimbo, Kaoru Toya, Masafumi Matsumoto, Jinya Mitsui, Toshinori Tsuji

"The Toyama Line is under construction as a natural gas pipeline with a length of 102 km from Itoigawa City to Toyama City. A 2 km-long tunnel section of the pipeline that we are reporting here is being excavated in a mountain area away from an urban area. The geology under which the tunnel is constructed is collapsible fractured breccia slate and Holocene sandy soil. Other tunnels of the Hokuriku Expressway and Hokuriku Shinkansen are in service above the tunnel route. From the starting shaft on Toyama side, conventional tunneling was adopted to facilitate excavating the base rock layer and maintain enough distance from the Hokuriku Expressway tunnel. From the starting shaft on the Itoigawa side, TBM tunneling was adopted to cope with the unconsolidated soft ground for a 200 m-long section from the shaft. We will discuss the issues and countermeasures concerning the selection of a tunnel route and excavation methods, performance of both conventional and TBM tunneling, and underground connecting of these tunnels excavated by conventional (NATM) and TBM methods under a high groundwater pressure up to 1.2 MPa. INTRODUCTION AND BACKGROUND The International Petroleum Exploration Teiseki Co., Ltd. (INPEX) is constructing a high-pressure main pipeline network in the Toyama Prefecture area to promote the use and reliable supply of natural gas as shown in Figure 1. As part of the Toyama line project that has a total length of 102 km, A-1 construction, the nearest section to the tunneling starting point in Itoigawa City, where various tunnel excavation methods have been adopted to install the high-pressure pipeline 20 inches in diameter, a 2 km tunnel in the A-1 construction section discussed here is to be excavated by conventional and TBM methods in a mountain area. Based on environmental studies such as traffic jams due to frequent traffic of heavy vehicles disposing of soil, and the effects of dust, noise and vibration during construction, we selected the route to install the gas pipeline in a mountain area as shown in Figure 2, where the impact on the surrounding environment could be minimized."

Jan 1, 2016

By Stefano Ceccotto, Eugenio Trussoni

"INTRODUCTION Contemporary city is made of layers. Physical structures layers (built fabric, residential, commercial industrial etc. ), infrastructural layers (below and above ground), “green” layers (parks and open spaces), and also informational layers, i.e. connections, links, between sectors of the city and other territories. The “city of layers” concept represents the exercise of “rebuilding the city” per each layer, highlighting those physical built structures that are functional to define a relation. For example, if consider the “connection” relation, the city is re-designed by considering only transportation built structures. The layer obtained in such fashion is hence the “transportation” layer, including below grade infrastructures (subways) and above grade lines (rail, bus, tramways etc.), as below shown in Figure 1.In this sense, the contemporary city is represented by separate constructs assembled together according to a specific functionality (e.g. “connection”). As a consequence, the relation between what is built underground, and the related above-ground development, can be perceived in his most evident appearance. What could happen within the contemporary city if the planning process would begin from below to above and not vice-versa?INTERACTION The question risen in the introduction is strategic when approaching the difficult task of designing (or re-designing) a multi-level organism like the contemporary city. Nowadays, the theme of integration between underground and at-grade master planning has become the subject of many urban renovation projects, where the design process has begun within the transportation layer, underground, and further developed by interacting with at-grade structures already existing or in phase of design.A series of case studies where below/above interaction plays a key role in the project will be further analyzed. Moreover, it is relevant to understand the mechanics of an urban transformation process that originates within the transportation layer and ends up with the design of entire sectors of the city. The Transit Oriented Development approach is a useful tool to clearly understand such transformation process. TOD has become, in particular in the last decade, one of the most effective tools for urban design, in order to solve simultaneously the many different instances related to transit planning, urban design and real estate market."

Jan 1, 2016

By M. Buxton

"Advanced data acquisition and process modelling technology provides online data and decision support about different aspects of the resource extraction process. Real-time approaches have recently been applied to utilize the value of this information for improved production control in mineral resource extraction in different operational set ups including coal, polymetallic ore and gold deposits. The key concept of these approaches promotes the change in paradigm from discontinuous intermittent process monitoring to a continuous process and quality management system in the resource extraction process. The framework includes a real-time feedback control loop that rapidly links online material characteristics data acquired during extraction at the mining face, during material handling and processing with a sequentially up-datable resource model. This will allow near real-time optimization of decisions related to long-term planning, short-term sequencing and production control. The contribution reviews recent developments in the three main constituents sensor based material characterisation, rapid updating of grade control models and simulation based optimization for improved production control. Technological readiness is assessed and critical gaps for further technology development are identified. The value added is illustrated by means of selected case studies. INTRODUCTION With the depletion of known and established mineral reserves, the decrease in head grades and the continuing demand of mineral raw materials by the modern society, future exploitation will move towards extraction of deposits under geologically more complex conditions. Complex deposits are characterized by a low continuity in grade, presence of deleterious elements such as arsenic and high irregularity in the geometry of the ore boundaries. The profitable exploitation of such deposits becomes significantly more challenging. To be able to better utilize such unconventional mineral resources of the future, smart autonomous mining systems are needed, which integrate local exploration of spatially varying material characteristics in–situ and have the ability to follow and extract the pay zones in the ore body while minimizing dilution (Buxton and Benndorf, 2013). The main barriers to overcome for the successful economic exploitation are: • effective grade control which will maximize resource potential along the whole value chain, • minimization of handling zero-value material introduced by dilution, thus • reducing unnecessary expenditure of energy and financial resources and • management and control of the geological uncertainty due to limited information available,"

Jan 1, 2017

By Edwin B. Wilson

Over the past several years, state governments have been vigorously refurbishing old health department agencies and smoke control laws in anticipation of pending federal developments. Many states now possess a mature air pollution control administrative organization and a fairly sophisticated set of regulations on air pollution, This developing network of state control legislation and regulation is the machinery which will be called upon to implement federal standards, In order to prevent the wasted effort and resources which inevitably result from hasty action, industry should be in con- tact with local and state control agencies and be familiar with lines of communication to agency representatives. Thorough knowledge of applicable laws and regulations, both current and pending, is required. Moreover, federal law and future federal air pollution control plans, should be well known. Industrial air pollution control should be geared to a long range plan which utilizes existing technology while at the same the recognizing that today's technology will be improved upon with time, Regulation, too, can be expected to become more stringent. The implications of air pollution control in the Appalachian region of the United States will be felt most strongly by the coal industry of this area. Either directly or indirectly most regulations in these states have a significant bearing on coal mining, processing, utilization or waste disposal. The extent of coal-related activity in the Appalachian States of West Virginia, Pennsylvania, Maryland, Virginia, Kentucky, and Tennessee can be observed from the data provided in Table I. This data indicates that 86 percent of active bituminous coal mines and 69 percent of bituminous coal production were accounted for by these states. The purpose of this paper is to provide information on current and proposed legislation and regulations on air pollution in the Appalachian states, The information should prove valuable not only to the coal industry but also to industry in general as a means of evaluating both pollution control action that has been taken to date and the course of future control measures. Reference information in the forms of addresses of appropriate agencies and citations to specific state laws and regulations is provided. All information is current as of February, 1969.

Jan 1, 1969

By Michael Brittan

The Delkor Linear Screen represents an important screening innovation in the minerals industry. Applications geared to the enhancement of gold processing efficiency through coarse screening are presented. Recent developments in the use of the Linear Screen as a fine screening classification device in mill circuits are also discussed.

Jan 1, 1998

By Dale W. Norris

United States Steel's Cumberland Coal Operations is located in Greene County in the southwest corner of Pennsylvania. The mine and related facilities have been in operation since September of 1977. Production from this mine, U. S. Steel's first commercial coal mining venture, will eventually reach a level of 2.72 million mt of clean coal per year and is totally committed to electric power generation. Cumberland is a slope mine in the Pittsburgh seam and is mined by continuous mining machines and longwall. The coal from the mine is trans- ported by belt to the surface, taken through a rotary breaker for initial preparation, and stored in raw coal silos. It is then processed through the preparation plant and taken to a clean coal silo where it is held for train loading. Cumberland Mine operates its am 28.16 km railroad to transport the coal to the Monongahela River. The unit train consists of thirty-one 90 mt cars. The coal, once loaded on barges, is then shipped to the customer. Cumberland Mine is one of the most modern coal preparation and unit train loading systems in the nation. The preparation plant is de- signed to receive coal from the silos at a rate of 720 at per hour. The +6.35 mm material is screened out and cleaned in a Daniels heavy media vessel with two 3.35 m weirs. Minus 6.35 mm material is fed to sixteen #88 Deister concentrating tables. The cleaned coal from this circuit is dewatered, and all effluents from the mechanical dewatering report to the classifying Cyclone sump for classification through ten 35.6 cm cyclones. The cyclones overflow material (-150 mesh) is processed through two banks of three 8.5 m3 Denver D.R. flotation machines. The cyclone underflow pro- duct (28-1 0 mesh) is processed in two banks of 5 six 2.83 m Denver Sub A machines. The clean flotation product is then dewatered in Bird screen bowl centrifuges, blended with the other clean coal size fractions, and the total plant product further dewatered in a thermal dryer.

Jan 1, 1980

By James Matlock

The announcement of a minable reserve of 13.6 Mt (16 million tons) averaging 0.9 g/t (0.027 oz per ton) Au and 2.4 g/t (0.71 oz per ton) Ag for the open pit-heap leach reserve at Red Mountain No. 3 in Ouray County, Colorado, by Cornucopia Resources in November 1985 brings another open pit-heap leach precious metal ore body to the production stage. With about 8.2 Mt (9 million tons) of waste and metallurgical studies showing acceptable recovery rates, low reagent consumption, and good final percentage recovery, Red Mountain is a discovery that will add to the precious metal inventory of the US. Frank Baumgaruler of Denver, CO, recognized the precious metal potential in Red Mountain No. 3 and acquired all of the old claims. James Matlock conducted a field reconnaissance over Red Mountain No. 3 independently of the Baumgartner activities and recognized epithermal alteration and mineralization in the Tertiary volcanics. He recommended acquisition of the ground and was able to obtain rights and drill six core holes for Amoco in 1982. Amoco drilled a further nine core holes in 1983, but then dropped the property. Cyrano Resources examined the data and through its consulting geologist, V.F. Hollister, acquired the rights dropped by Amoco. In 1984 Cyrano began further drilling of the ore zone demonstrated by Amoco but they were then acquired by Cornucopia Resources. Cornucopia completed development of the property and commenced the permitting process in 1986. The property was recognized as a disseminated gold deposit by both Baumgartner and Matlock, and both deserve credit for properly evaluating mineralized outcrop in the Tertiary volcanics. However, Cornucopia recognized the profit potential in the heap leach exploitation of the ores and de- serves credit for completion of premine feasibility studies. The discovery is clearly a geological one, but the premine engineering studies were essential to the conversion of the prospect to a commercial mining enterprise. The deposit lies on the circular bounding fault of the Silverton caldera. Two reprints follow that help understand the geologic setting of the ore controls.

Jan 1, 1990

By Changwoo Lee, Jan M. Mutmansky

Introduction Recognition of Coal Workers' Pneumoconiosis (CWP) as a major occupational disease has affected various aspects of the coal mining industry in the United States as well as in almost all major coal producing countries. Regulations related to the control of coal mine dust forced mine operators to modify their mining and ventilation practices. As the coal production record of the last 15 years shows, this had both direct and indirect impacts on the productivity and production costs. To identify the causes of CWP, many research efforts have been made through- out the world. Most of these studies were epidemiological in nature, attempting to pinpoint exposure and seam variables that affected the incidence of the disease. Other studies have been oriented toward the elemental and mineralogical composition of the coal dust in the mine atmosphere and in the miners' lungs. These studies indicate that there may exist some relationships between the characteristics of the coal mine dust and the prevalence of the disease. Some of the variables that are thought to affect the occurrence of CWP are the mass of the dust in the working place, the rank of the coal, the existence of certain trace elements, the free silica content of the coal, and the existence of other minerals in the respirable dust. A more complete description of these previous re- search studies has appeared elsewhere (Mutmansky and Lee, 1984). The behavior of particles in the human lung is known to be governed by their aerodynamic diameter, which is defined as the diameter of a hypothetical spherical particle with unit density that exhibits the same settling velocity as the given particle. Because of this fact, the aerodynamic size distribution of coal mine dust is one of the parameters to be determined along with the other physical, elemental, and mineralogical characteristics. The objective of this paper is to establish a strategy for providing coal mine respirable dust samples for characterization purposes using instruments that classify according to the aerodynamic diameter. In addition, several findings concerning characterization methods will be presented. Choice of Samplers Most of the gravimetric dust collection devices that can be utilized in a mine environment can be

Jan 1, 1986

By A. Goulsbra, S. Gregory, P. Gelfil, V. Martins, R. Dunne

As a general rule for gold treatment the presence of reasonable amounts of 'coarse' free gold will dictate the use of a gravity circuit. The actual particle size of gold that constitutes the por­tion of' coarse' free gold can vary widely. The larger its size the more troublesome it is, mainly because of the tendency for this gold to quickly settle out from slurries in regions of relatively low velocities. There are a multitude of places where 'coarse' gold can find a resting place, namely, in chutes, between and behind lines, in pump hoppers and in pumps themselves. Fortunately, the problems associated with recovering very 'coarse' free gold, say greater than Imm, is rare on most gold mines that have grinding and cyanide leaching circuits. For these operations it is common practice to have a gravity circuit situated within the milling circuit to recover 'coarse' free gold. Should the 'coarse' free gold constitute 15% to 20% of the total gold in a deposit then its recovery by gravity separation is seri­ously considered. As a gold mine 'matures' the availability of soft oxide ore decreases and the likelihood that harder ore having sulphide gold association increases. To maintain gold production rates in this situation either the gold grade of the treated ore must increase or more ore needs to be treated. In the latter case this is achieved by installing more grinding capacity, an expensive option, or coarsing the grind, with the downside of loss in gold recovery. In general the less expensive capital options is fol­lowed. There is, however, some upside to improve recovery when reasonable quantities of sulphide containing gold are pre­sented that can be recovered by flotation or gravity separation. Concentrates produced from these unit operations can be finely ground and reintroduced to the cyanide leach circuit to improve gold recovery. This scenario is a much less costly option than one where all the ore is ground finer. In this paper the experiences of recovering gravity gold from the Telfer Gold Mine, and gold associated pyrite from the New Celebration Mine will be discussed.

Jan 1, 1996

By W. Holding

Since the 1975 International Mine Ventilation Congress in Johannesburg there has been a trend in South Africa towards making the mine ventilation departments responsible for monitoring the total environment. This includes the taking of noise and illumination measurements and there is in fact a debate taking place as to whether the departmental title should be changed to 'Environmental Control Department'. The organisers of the 2nd international Mine Ventilation Congress have decided that noise and illumination will not be included as Congress subjects and 'Total Environment' includes only those facets which are open to debate at the Congress. The choice of mine is significant in that while most Congress papers from South Africa will be devoted either to coal mining or to the somewhat unique deep level gold mines, Prieska Copper Mine is a mine which can easily be identified with similar mines in many other parts of the world. The mine is situated some 750 km south west of Johannesburg and about 600 km north east of Cape Town. Current production (ore and waste) is about 340 000 tons per month and the total underground labour force is just over 2 000. The ore body is a massive sulphide, the main minerals being copper and zinc and the method of mining is sub-level open stoping. Daily average surface temperature conditions range from 85°F (29.5°C) dry bulb and 69.8°F (21°C) wet bulb in mid-summer to 42°F (5.5°C) dry bulb and 36.5°F (2.5°C) wet bulb in mid winter. The information presented in-this paper is limited to what can be gathered by mine ventilation staff as part of an on-going exercise and is obviously not as comprehensive as would be the case if a fully equipped research establishment were to become involved. The paper will be divided into three sections 1) Gases 2) Dust 3) Heat In each section statutory and/or other standards will be set down followed by a discussion of assessment and in some cases control methods.

Jan 1, 1980

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 Greg Hodges

Sand-and-gravel aggregates have become the number-one, nonmetallic-mineral resource in the world. Surficial aggregate deposits of economic size are becoming increasingly rare in most parts of Canada. In southern Saskatchewan, this is especially true, and detection and delineation of intertill sand-and-gravel deposits with airborne electromagnetic (EM) surveys have proven very successful. Airborne and ground geophysical surveys detect such deposits by their resistivity contrast relative to the surrounding clay-rich soils. Dighem helicopter-borne electromagnetic surveys map soil variations over a large area quickly and cost effectively, greatly reducing the cost of detecting and mapping deposits compared with traditional methods (air-photo interpretation, ground EM, and drilling.). The multiple-frequency EM system used by Dighem can map variations both horizontally and vertically. Magnetic data collected simultaneously are useful in mapping bedrock geology. Both resistivity and bedrock maps aid in the important task of reducing drilling costs and person-hours in the field. The results of the survey are presented as maps of ground resistivity, which are relatively easy to interpret. These maps are produced in the field at the time of the survey, making quick follow-up of the survey possible. Airborne EM surveys can map the extent and depth of aggregate deposits more effectively than is practical from the ground. Since aggregate deposits can vary tremendously in a very short distance (<300 m) large-area EM maps can show both local area variability and also help develop intertill trends. A test survey for the Saskatchewan Highways and Transportation Department over a 3-km by 5-km area mapped all the known deposits as well as some unknown deposits, subsequently proven by drilling. The test-survey data show that the method not only detected the deposits, but also gave an estimate of the shape (volume) of each of the deposits. Comparison of the data to drill sections shows excellent correlation. Theoretical modelling demonstrates that the multifrequency system can discriminate sand and gravel from bedrock ridges. Since the successful test work, about 725 km2 of ground have been surveyed, resulting in the discovery of four new deposits, which can be used immediately, resulting in significant savings for the Saskatchewan government and taxpayer.

Jan 1, 1999

By D. E. Martin, K. J. Hamill, H. J. Miller

1. INTRODUCTION In April 1979, the U. S. Nuclear Regulatory Commission issued the Draft Generic Environmental Impact Statement (GEIS) on Uranium Milling (NUREG-0511) for public comment. While the GEIS is a broad environmental impact assessment of the U.S. uranium milling industry as a whole, its primary focus is on the issue of uranium mill tailings disposal and long term isolation. In August of 1979, proposed regulations (U.S. Federal Register Notice 44FR50012), incorporating both conclusions of the GEIS and provisions of recent U.S. legislation on uranium mill tailings (Uranium Mill Tailings Radiation Control Act of 1978--UMTRCA), were also issued for public comment. This paper (1) briefly reviews the major conclusions of the draft GEIS, (2) summarizes the major elements and rationale of the associated, proposed regulations, and (3) reviews some of the major issues raised during the public comment period and changes which the NRC staff expects will be made in finalizing the GEIS and regulations. The risk in summarizing a document of such broad scope and complexity as the GEIS is that the depth of evaluation and the full technical bases for conclusions reached may not be adequately conveyed. Recognizing this, those Sections of the draft GEIS where a more complete discussion of the issues is presented are parenthetically noted in this paper in order to facilitate location of additional background and supporting material. 2. GENERAL CONCLUSIONS In the GEIS, a full range of tailings disposal alternatives was considered. These alternatives ranged from the past practice of doing little or nothing to control tailings, to advanced treatment alternatives such as nitric acid leaching to increase removal of radioactive elements and fixation of tailings in cement or asphalt. Our broad conclusions were: -Any alternative which results in the need for ongoing, active maintenance to assure long term containment, is unacceptable. (12.3.2.1) -Advanced treatment alternatives are unwarranted since they offer uncertain incremental benefits yet involve costs which may be as much as an order of magnitude greater than costs associated with acceptable alternatives. In addition, the advanced treatment

Jan 1, 1980

By Z. Kowalski

In the non-operational ?Górka? quarry, there are situated both a waste disposal site of an area of 6.7 ha, containing approximately 1 million ton wastes from high aluminium content materials (incl. about 400000 t of wastes from aluminum hydroxide production), and a pond of an area of roughly 3 ha, up to 15 m deep, with about 400000 m3 of polluted water and infiltrates from the disposal site mentioned. The basic problem related to the effluents in the Górka pond is both their high alkalinity (pH 12-13.4) and a variable analysis of pollutants whose level increases appreciably with the pond?s depth. The solution offered provides, first of all, remedial pumping and a treatment of effluents retained in the Górka reservoir. Effluents would be treated in a reverse osmosis plant according to a process verified so far on a quarter-commercial scale. The treatment process by-product, a brine solution (containing about 25% NaCl) whose amount may reach up to 100000 m3 might be supplied to the Debiensko Mine, which produces technological salt from salt-bearing mine waters. In parallel, an intake of underflows of infiltrates would be provided (previous geochemical identification) in order to take them away from the high aluminum site (by means of deep wells, and possibly girdling ditches). Such effluents would be subject to treatment. The successive stage is the utilization of approx. 50000 m3 of bottom slurry, left in the emptied reservoir, in the production of self-solidifying mixtures, which would be then used for sealing the bottom and the banks of the Górka reservoir. The empty and sealed reservoir would be filled up with a volume of approx. 600000 t of ashes, coming from coal burning in the thermal-electric power station. For the last stage, instead, is scheduled the rehabilitation of the entire waste disposal site in the Górka quarry. The site will be drained, covered with a leveling, sealing and rehabilitating layer, which will allow to introduce plants on the rehabilitated waste site. Later on, the area could be turned into a town park

Jan 1, 2006

By James R. Dunn

The nature of water and clay in carbonate rocks is currently being investigated at Rensselaer Polytechnic Institute by various thermal and sorption techniques. Two basic concepts &apos;led to the present research. (1) To explain the expansion and contraction on wetting and drying of some unsound argillaceous carbonate rocks, it was postulated that the pore space around each clay particle is such that when water is sorbed by the clay, force is exerted against the pore walls. (2) The clays in expansive rocks are rejected from the growing dolomite crystals during their growth, and form a more or less connected network, thereby becoming "wettable," or available to water. New quantitative cold differential-thermal-analysis (electrocalorimetric) equipment was designed and constructed to check the "limited space" and "wettable clay" concepts and to determine the thermal nature of the transition of water to ice in rocks. This DTA equipment can detect the release of heat in freezing of less than 0.001 per cent water in a rock. Twenty-three rock cores (nine sound and fourteen unsound) and 4 procelain cylinders for standards were studied. In the nine sound rocks and in all the procelain cylinders, the rapid freezing of from 50 to 100 per cent of the water was readily detectable after 7 to 10° C of supercooling. No further freezing could be detected to -20° C. However, in eleven of the fourteen unsound rocks, no freezing was detected to as low as -40° C; in the other three, less than 50 per cent of the water froze. As a check of the DTA measurements, adsorption isotherms were determined for all materials. Calculations of theoretical freezing points for sorbed water again demonstrated that the least sound rocks had the most nonfreezable water. "Frost" sensitivity in these carbonate rocks is, therefore, probably not the result of the force of expansion of water to ice. The disruptive force is believed to result from expansion of sorbed, ordered water on clay surfaces. The relationship between the unfilled rock pores after 24-hour water saturation and the water sorbed at 85 per cent humidity at 30° C (i.e., the theoretical nonfreezable water delineates the sound and unsound carbonate rocks.

Jan 1, 1966

By Carlon C. Chambers

INTRODUCTION Manufacturer sponsored research over the past three years has proven the suitability of styrene-butadiene/ asphalt membranes in many waste disposal seepage control applications for the mining industry in general and uranium mining and milling in particular. The class of membranes that have been tested are SBR/asphalt blends containing up to 68 weight percent asphalt, the balance being elastomeric polymers, fillers and phase compatibility promoters. These membranes are classified as thermoplastic, elastomeric materials and can be hot spray applied to any moderately dry substrate at 177°C (350°F), and placed in service within one hour of application. The properties of this membrane that make it suitable for use as an engineering_ material in these applications are discussed. These properties include chemical resistance, bacterial resistance, UV light resistance, permeability, stress/strain characteristics and bonding data. The favorable economics of the system are also discussed. The preliminary raw test data on the above properties were reported in a previous paper, (Chambers, 1980) and most will not be repeated here. Instead, this report considers the original data in relation to subsequent data and concentrates on interpretation of the trends for engineering purposes. However, several of the pictures contained in the original paper are reproduced in this report for illustration purposes. BACKGROUND Asphalt alone has a long history of use as a water-stop material. Its limitations of becoming brittle when cold and soft when hot, however, are well recognized. The service temperature for common grades of asphalt is usually in the 4° to 49°C (40° to 120° F) range. Modifications to the base asphalt can generally improve its performance at the high end of the temperature range by raising its softening point, but only the addition of one class of modifiers, elastomeric polymers, improves low temperature flexibility as well and also adds resilience. Both of these properties are of extreme importance if the waterstop material is to maintain its integrity when used on substrates which are unstable, non-cohesive, discontinuous or have significant expansion/constraction coefficients. Although there are many elastomeric polymers which can be used with

Jan 1, 1980

By M. Z. Emad, M. U. Khan

"Coal mines opting for longwall mining or its variations rely on the main and tail gates for production. Stability of these entries or crosscuts is crucial in coal mining operations. Roof or strata failure can be fatal, may lead to property loss and delay in production. Failure of the gates depends upon many factors including the mining method, panel dimensions, pillar width, mine depth, caving rate, dimensions of gates and roof strength properties. In Pakistan coal is mined through a variation of longwall mining method with almost no mechanization while using timber as a primary support. Timber support as chock is very useful in coal mines especially in overhanging face. Similarly gate entries and coal faces are supported by chock supports throughout their length. In this paper the stability of the longwall gate is assessed for a typical coal mine in Pakistan by using finite element code. Numerical modelling considerations for gate entries are discussed. A model parametric study is performed for key factors. The results showed that the existing mining practice is not suitable and there is a need to review the mining approach. INTRODUCTION Main and tail gate entries leading to longwall mining panel play a crucial role in production cycle. Failure of any of these may lead to loss of life, property and production delays. The stability of gate entries depends primarily on the nature of loading and stresses incurred. It is relatively easier to assess the ground response to production for common longwall mining panel. In thin-seam coal mines the gate entries are generally supported throughout their length by timber made chock supports. The tailgates receive huge deformations and stresses during the mining and backfilling cycle. The chock supports are required to take care of rock falls leading to blockage of entries causing production delays and loss of capital. A number of supports are available for supporting the gate entries (Hoek and Brown 1980; Brady and Brown 1985). The support system can be selected based on load-deformation characteristics including the yielding behavior, pre- and post-yielding behavior (Barczak, 2003). The principal of support selection is that the support characteristics must match the ground response in order to maintain the gate entries (Mucho, et al., 1999). It has been observed that thin-seam mining (<1 m) is very challenging and it is necessary to develop an understanding of ground mechanics before the selection of an efficient support system Dolinar (2003). The chock supports have been tested for load-deformation characteristics in the laboratory (Barczak 2003). But the ground and support interaction, response and loads must be assessed for individual site. This can be accomplished by in-situ testing and observations at few locations. The generated data is generally insufficient for complete understanding. Numerical models can combine the data generated in the laboratory and on-site to fulfill the requirements."

Jan 1, 2017