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By Sheridan A. Glen

As the Federal government along with individual states continue to grapple with the job of refining a comprehensive energy policy, coal continually stands out as an energy source which heralds a combination of old and new capabilities like an energy planners prophecy, but which is plagued with serious environmental constraints. To determine what level of coal utilization is ultimately possible for states East of the Mississippi, whose high sulfur content coal presents the most paramount of challenges, one must consider product availability, via existing transportation modes, the developing industrial markets and the ability of coal to meet the challenge of becoming an environmentally acceptable fuel. Gasification is emerging as a form of utilization, which during the next twenty years stands a good chance of being able to meet the challenge of making coal an environmentally clean, easily transport-able and usable fuel. It can be argued that, of all the potential ways of utilizing high sulfur coal, coal gasification is perhaps the most expensive, the most financially risky and carries environmental liabilities of its own. Synthetic gas and oil markets will undeniably be a function of price and demand, which, for the purposes of this paper, I'm assuming will begin to merge in the late 1980's and into the 1990's. This is also presuming that public utility commissions will allow favorable price structure ruling so that gasified coal products can be rolled into their respective rate base, much the same as synthetic natural gas from petroleum by-products are currently being priced. The comparative economic markets of coal to gas pro-duct have plenty of time to mature. There is an approximate twelve-year lead time needed to bring coal gasification plants on line which will be able to compete in the market place for natural gas and oil customers.

Jan 1, 1977

By I. Douni

The aim of this study is to synthesize hydrated compounds of calcium silicate (tobermorite) using as siliceous source perlite milling process wastes, containing more than 70% of SiO2. Calcium silicate hydrates are mainly used for construction of lightweight building materials, plasters, tiles and filters. The effect of temperature, time and particle size of perlite on the quality and composition of the solid product was studied. The solid products were characterized by X-ray Diffractometry, Differential Thermal Analysis and the amount of Acid Insoluble Residue. The synthesis of tobermorite was per-formed by the hydrothermal treatment of perlite waste with a saturated calcium hydroxide solution at a molar ratio CaO/SiO2 of 1, liquid to solid ratio 10 mL/g and 1% w.t. NaOH addition. Three experimental sets were performed. In the first series of experiments the synthesis temperature was kept constant at 205°C while the synthesis time varied from 0.5 h to 24 h. In the second experimental series the synthesis time was kept constant at 2 h while the temperature varied between 150°C and 245°C. In the third experimental set the temperature was 205°C and the reaction time was 2 hours and two perlite waste size fractions were used, a coarse (d50=18 µm) and a fine grained one (d50=8 µm). Reaction products consisted of semicrystalline calcium silicate hydrate (I) and crystalline Al-substituted tobermorite or a mixture of both. An isomorphic Si4+ ions substitution with Al3+ ions in the hydrated calcium silicate lattice was detected by thermal analysis. The experimental results show that good quality crystalline Al-tobermorite can be produced after 6 hours of autoclaving at 205°C or after 2 hours of hydro-thermal treatment at 225°C. Generally, the in-crease of synthesis temperature or time favors the crystallization of calcium silicate phases and enriches them in aluminum. The use of fine grain size perlite is more efficient for the hydrothermal synthesis of calcium silicate hydrates.

Jan 1, 2006

By P. M. Soupios

An integrated suite of environmental methods was used to characterize the hydrogeological, geological and tectonic regimes of the study area, to determine the geometry of the landfill (depth and spatial extent of electrically conductive anomalies), to define the anisotropy caused by bedrock fabric fractures and to locate potential zones of electrically conductive contamination. The study area which covers an area of about 0.08 Km2 is a municipal solid waste site (MSW), located 20Km West of Herakleion in the central part of Crete (S. Greece). The landfill is located in a northwest oriented valley with highlands to the northeast and southwest. The combination of geophysical methods and chemical analysis are commonly implemented for characterization and management of land-fills. At the particular site, geophysical methods were focused on studying the electrical insolating properties of the materials, electrical con-ducting properties of fluids (leachates) and electromagnetic properties of the disturbed regolith materials in the burial zones. Three different types of geophysical surveys were performed: 1) 2D electrical tomography (ERT), 2) electro-magnetic measurements using very low frequencies (VLF) and 3) electromagnetic conductivity (EM31). Furthermore, in order to calibrate the geophysical methods dielectric spectrometry measurements are conducted. To evaluate the environmental degradation of the area, soil and liquids samples were collected.

Jan 1, 2005

A computer simulation of the automatic control of continuous mining machines has been prepared, similar to previous simulations of longwall mining systems and coal thickness sensors. The simulation allows for programmed variation of the horizon detection method, the azimuthal guidance system, the type and configuration of the miner, varying hardness in the unmined face material (leading to varying error in the machine heading), and the miner's cutting cycle. It simulates control of the miner in three axes. Use of the simulator makes it possible to anticipate problems arising from the complex character of underground mining, which include unpredictable multi-pass coupling and unpredictable variation in geological conditions.

Jan 1, 1993

By S. Tuylu, D. Adiguzel, A. Bascetin, H. Eker

"Tailings can be more stable in-site where they are stored and and so the risk of conventional tailings dam accidents can be reduced by alternative methods. In recent years, surface paste disposal (SPD) method is one of the alternative tailings storage methods. According to the results obtained from the previous lab scale experiments, optimum storage design was determined and then, this design was carried out in-site application under atmospheric conditions by a pilot scale tests. In the field study, two separate dams with no environmental hazards were established by the hazardous waste storage directive, whose surface area is measured as 400cm × 200cm. Also physical changes in the paste tailings were measured by the sensors such as volumetric water content, mutric suction and oxygen consumption. In addition, seepage water was collected in the drainage pool and examined for acid mine drainage and metal mobilization risks. As a result of the preliminary data obtained from measurements of pilot scale tests, when the pH value of seepage in the cemented dam (only 1th and 10th layers with cemented) is about 11, the pH value of seepage in the uncemented (reference) dam is measured at 8-9. INTRODUCTION Environmental damages occurred during the deposition of mine process tailings at surface using conventional methods (tailings dam etc.) can be reduced and/or eliminated with the use of new technologies and methods to an important extent. Nowadays, it has been investigated to safely deposit metal mine wastes generally discharged into surface tailings dams, seas, rivers, creeks etc. using Paste Tailing Technology which gains the growing importance in recent years. Meanwhile, Paste Tailings Technology has two applications in industry as an underground paste backfill and surface paste deposition. Particularly scientific studies about deposition of process tailings as paste sample in underground and surface have been increased. These studies showed that surface paste deposition can minimize the free water amount which is the biggest problem in conventional tailings dams. Additionally, it also provides less particle segregation, in other words, the formation of more homogenous material, the development of geotechnical properties which causes to obtain more stable material, increases the strength and stability of the paste with addition of binder where necessary surface paste material, and reduces the risk of Acid Mine Drainage (AMD) (Bascetin et al., 2017a). Theriault et al. (2003), Martin et al. (2006) and Simms et al. (2007) reported that Bulyanhulu mine in Tanzania is the first gold mine to employ surface paste disposal (SPD) worldwide. Here, tailings are deposited alternately via several towers. The tailings flow away from each tower to forming a conical deposit. Each layer had a lower thickness than 30 cm. The fresh tailings were poured on top of drying and hardening layer after a waiting period of 5-30 days. No cement was added into the tailings to prepare paste material. Uncemented paste was deposited by a solid content of 73% which corresponded to a 250 mm slump cone height (Yilmaz et al., 2014). In a study conducted by Yilmaz (2010) illustrates the preliminary results of a field cell testing undertaken to investigate the effect of in situ climate conditions and material properties on the performance and quality of fine-grained, sulphide-rich paste tailings at the LaRonde mine in Quebec, Canada. A total of two field cells are constructed in the surface disposal site of the mine and categorized as cemented cell CC and uncemented cell UC (Bascetin et al., 2017b)."

Jan 1, 2018

By C. E. Capes

The spherical agglomeration process provides an attractive method for the cleaning and recovery of fine coals in the form of compact oil-bonded pellets. In treating a washery effluent containing 50% minus 20 micron material by this technique, the slurry was first mixed under vigorous agitation with oil to deash and dewater the fine coal. The flocculated coal pulp was then formed into larger agglomerates on a modified balling disc. The operation of a semi-pilot scale process is described and an analysis of some of the operating and system variables is given. A semi-theoretical expression to predict the final agglomerate size under various conditions is derived and compared with the experimental data. Coal producers are faced with a growing requirement to clean and recover fine mesh coals. Greater mechanization of the extractive and preparation processes has resulted in finer-sized products containing larger quantities of associated foreign matter and preparation plant effluents contain quantities of fine coals which are potentially valuable. These losses will probably increase with the expansion of production and will require the development of effective disposal and utilization processes under pressure of the lack of adequate disposal areas, the enforcement of air and stream pollution laws, and the economic need to obtain the maximum yield of salable product(1)

Jan 1, 1970

By MEHMET KIZIL, PETER KNIGHTS, ROYAL REA

A 1/20 scale experimental dozer push test rig was designed and constructed to quantify the expected production rates (loose cubic metres per hour) for dozers operating in hard rock bulk push applications. The particle size distribution of the material employed in the test rig was modelled on a fragmented muckpile representative of that for a typical surface copper/gold mine overburden. A commercially available road base material was found to be highly representative of site conditions. Buckingham Pi theory was applied to mathematically develop factors for scaling up dozer productivity parameters, including blade loads and push times. Dozer production rates were investigated for various dozing distances and slope angles. A series of instantaneous productivity curves were produced which are applicable for use in hard rock dozer push operations. Currently, it is difficult to estimate dozer push productivity in hard rock environments due to dozer productivity correction factors that are empirical in nature and provide only discrete, end-point values for a range of operating conditions. The productivity curves produced demonstrate that dozer productivity declines rapidly over the range of 10 m to 40 m. As such, it is recommended that efficient bulk dozing operations in hard rock mining blocks should not exceed 40 m dozing distance. Further testing of muckpile conditions with increased clay and moisture content would be beneficial in order to better understand and quantify the effects of cohesion on hard rock dozer push productivity.

Nov 23, 2021

By Ernest N. Wolff

You here are all familar with the myriad of new laws, some enacted and some pending, that affect the mining industry. These laws, for example those dealing with suspended matter, affect us in Alaska as they do you. Likewise, our friends in government, the Geological Survey and the Bureau of Mines, provide us with the same fine services that they do elsewhere. I am not going to speak today about these, but concentrate on one act of Washington, D.C. the impact of which is felt, for now at least, principally in Alaska. A little more than a year ago, I spoke in Spokane on the subject, "Governmental Challenge to Mineral Development in Alaska." I outlined some of the policies of Government which were operating to change the rules under which the industry operates and to alter the relation- ship between government, industry, and the individual. At that time the Native Claims Settlement Act had not been passed, but was on the verge of being so. In reading over what I said in Spokane, I note that I touched on many points where Government was actually challenging mineral development in Alaska. With the passage of the Alaska Native Claims Settlement Act, many of these actions were given a cloak of legality, and machinery was set up to concentrate the drive to tie up the public domain, machinery which will allow govern- mental control and interference with the actions of individuals on something like 90% of Alaska's land surface. This remarkable law is going to affect each and every one of you. Now, a year after its passage, we are only just beginning to see its lesson for the future. It was created by a coalition of powerful groups, who got other groups to support them by promising to deliver something they had no intention of delivering. Alaskan issues are again being used to get various groups not to oppose legislation which will severely harm them. It will help to understand the nature of this new drive if we understand the Native Claims Act and how it came into being.

Jan 1, 1973

By Mike Perkins

The Summitville Au-Ag-Cu district in the southeastern part of the San Juan volcanic field has been a major gold producer in Colorado. Mineralization is hosted by the composite South Mountain quartz latite porphyry volcanic dome, which is believed to have been localized by the intersection of the northwest margin of the Platoro-Summitville caldera complex and the northwest-trending Platoro fracture zone. K-Ar age dates indicate that alteration and mineralization were nearly contemporaneous with emplacement of the dome at 23-20 m.y. ago, 6-7 m.y. after collapse of the Platoroo-Summitville caldera complex. The dome consists of at least four major phases including strongly altered quartz latite porphyry; a late-mineral, coarse-grained sanidine quartz latite porphyry; and postmineral quartz latite dikes. The dome was emplaced into intracaldera rhyodacite and andesite. Gold-silver-copper mineralization is concentrated near the top of the dome and is associated with pods, pipes and steeply dipping tabular zones of silicification and advanced argillic alteration. Alteration is zoned outwards from the center of mineralization through argillically and propylitically altered rocks, and is largely confined to the area of the dome. Trace element geochemical patterns for the deposit indicate a central zone of anomalous As-Au-Pb-Ag and low Mn within an exterior zone of anomalous Ag-Au-Pb-Hg and high Mn. The chief ore mineral is native gold which is associated with goethitic iron oxide in the oxide zone. In the sulfide zone, native gold is associated with copper sulfide-sulfosalt mineralization. A genetic model for the Summitville deposit is based on recent models of modern geothermal systems, with which it shows similarities in alteration, ore mineralogy, zoning, and structural patterns.

Jan 1, 2013

By A. J. Basu

An overview of the evolution of computerized mine planning and design has been given, emphasizing the need for a knowledge-based system for planning and design of underground coal mines. An outline for the development methodology and procedure has been provided. Problem structuring guidelines have been used to incorporate intelligence and integration to the design modules. A skeletal model for a mine planning and design expert system has been prescribed, and the development process has been documented in detail. A feasibility prototype has been developed to test the structure of the skeletal model and to ensure completeness of the design process. The feasibility prototype development and its contribution toward proto typing has been addressed in this paper. At present, prototype development is underway. The prototype is expected to be avail-able for testing and implementation in early 1991.

Jan 1, 1991

By J. Weng

The equations of heat conduction are numerically solved for two kinds of artificial freezing- mechanical freezing and liquid nitrogen freezing. A two dimensional finite difference model simulating the freezing field is developed. The procedure introduces a way to simulate the effect of latent heat released when water transforms from liquid to solid. The procedure also produces a way to calculate the harmonic mean of heat conductivity used when dealing with heterogeneous material. The theoretically derived temperature distributions in frozen soil are given and compared with measured data. An analysis is made on the thermal design in shaft freezing. The average temperature of frozen soil is calculated by using numerical integration. The regularity of development of frozen soil radius is revealed and given in an appropriate mathematical model.

Jan 2, 1984

By Guodong Li, Chenlin Wang, Zibiao Yu, Bo Xu

Abandoned coal mines have many underground space resources, such as roadways, shafts, and gobs. Among them, abandoned roadways are the best gas storage space for underground compressed air energy storage (CAES). However, CAES caverns have high air pressure and strict sealing requirements. Therefore, the stability and sealing of abandoned roadways under high internal pressure must be analyzed. Afterward, the suitability of abandoned roadways used for CAES caverns should be evaluated. In this study, the numerical simulation software FLAC3D was used to calculate the stress, deformation, plastic zone volume, and pore pressure of surrounding rock in an abandoned roadway under 10 MPa internal pressure. The influence of buried depth, surrounding rock grade, and in situ stress state on roadway stability and the effect of surrounding rock permeability on roadway sealing were analyzed. Results showed that the stress, displacement, and plastic zone volume of surrounding rock were affected by high internal pressure when the buried depth was less than 300 m, but high internal pressure had little effect on them when the buried depth was more than 300 m. The suitable range of buried depth was more than 300 m. The optimal choice of surrounding rock grade was I and II, followed by grades III, IV, and V. The optimal choice of in situ stress state was σH > σh > σv, followed by σH > σv > σh and σv > σH > σh. The sensitivity of the stability evaluation parameters was ranked in descending order as follows: buried depth, surrounding rock grade, and in situ stress state. When the surrounding rock permeability was less than 1 × 10− 14m2, the 24-h air leakage rate of the roadway was less than 1%. The suitable range of surrounding rock permeability was less than 1 × 10− 14m2.

May 23, 2023

By A. Ramage

Since late 2010, CH2M HILL has been working with a confidential client who holds a long-term commitment to sustainable development (SD). The commitment is aligned with all three elements of the triple bottom line: people and society, ecosystems and environment, and financial and economic systems. These commitments are carried forward by the firm?s executives, managers, and operational sites, and are evident in materials posted on the company?s public website. These materials include a formal sustainability report prepared in accordance with the Global Reporting Initiative (GRI) guidelines (GRI, 2006), a report that outlines key SD challenges and progress toward the GRI targets, and a delineation of risks and opportunities outlined in the firm?s Form 10-K and Annual Report. In keeping with its commitments to SD targets, our client wished to consider SD issues in its decision processes for facility expansion or new projects. The company engaged CH2M HILL to meet this goal, based on working relationships established through existing contracts and CH2M HILL?s leading capabilities in sustainable solutions.

Jan 1, 2012

By Haydn H. Murray

The area from Ohio on the east, Tennessee on the south, and Minnesota on the west: contains some very unique and useful clay deposits. Included are fireclays and plastic clays in Ohio, Kentucky, Indiana, Illinois, and Missouri; flint clays in Kentucky and Missouri; ball clays in Kentuckv and Tennessee; adsorbent clays (fuller's earth) in Missouri, southern Illinois, and Tennessee; and alluvial clays and shales for structural clay products from every state. Unique kaolin clays are known in Minnesota, Missouri, and southern Illinois and halloy-site localities are known in southern Indiana. The geology, physical properties, and uses or potential uses of these midwestern clays are described.

Jan 1, 1980

By Harvey Parker

This is part two of an article on the prominent role that the United States and its industry leaders have played on the International Tunnelling and Underground Space Association (ITA), which represents the underground construction and underground space industries worldwide. The U.S. is officially represented in ITA by UCA of SME. (Part one is in T&UC, June 2007, pp 39-42) Tunnel advances in 1960s and 1970s The 1960s and 1970s were active and productive times for the U.S. tunneling industry. During that time, federal programs, sponsored by the Federal Railroad Administration (FRA), the Office of High Speed Ground Transportation (OHSGT) and the Advanced Research Projects Administration (ARPA), stimulated tunnel research and development. Also, the American Society of Civil Engineers (ASCE) and SME collaborated to create the Underground Construction Research Council (UCRC) and the Rapid Excavation and Tunneling Conference (RETC) series.

Jan 1, 2007

By W. L. Hollinshead, Alwin Poltinger

GENERAL Tunneling by hand digging is as old as the history of humans. Mechanized tunneling did not begin to replace manual methods until around the beginning of the 19th century(Brunel patent, 1818). It brought with it a higher degree of safety for the workers and a much higher rate of boring. But for any kind of tunneling, an accurate and feasible method of survey must be accomplished during mining. That means, that for each tunnel project the most efficient survey method must be devised. The method to be defined depends on the spatial curve, diameter, speed of tunneling method, purpose of tunnel and contractual accuracy. The final accuracy of a finished tunnel is heavily dependent upon three critical elements: 1. Quality of the above ground survey 2. Tunnel traverse and directional transfer from above ground 3. Guidance for the mining job. Combining The Survey And The Guidance System Since the guidance system (GS) is one of the critical factors in the determination of the tunnel final accuracy, it is necessary to analyze how the directional control and tunnel traverse measurements can be effectively integrated into a GS. Any guidance system, whether manual or high technology, must continually detect and compensate for movement of its theodoliteor laser station standpoint. Movement beyond a preset allowable amount must generate a warning or error message to the user. Additionally, optical refraction can interfere with the results. Refraction will have an effect on any kind of optical GS. Therefore, careful selection of target and standpoint locations can minimize, but not completely eliminate, the influence of refraction. Some GS technologies, such as Gyro-based systems, are immune to the effects of refraction, but have other, methodical errors which will be described later in this paper. GUIDANCE Overview Why is a guidance system necessary? A GS, whether manual or automatic, compares the design direction and slope of a tunnel with the current position of the mining

Jan 1, 1997

By Neilson Rudd

Many deep well waste disposal. operations have adopted the technology of the petroleum industry but fail to make full use of the knowledge and experience upon which this technology is based. Inexperience in subsurface exploration commonly leads industrial personnel to an over simplified understanding of the complex subsurface rock/fluid environment and overly optimistic "degree of exploration /adequacy of knowledge" ratios. Several fundamental differences between disposal and petroleum production are discussed. In particular, the evolution of understanding of the subsurface in relation to degree of exploration is demonstrated by summarized case histories of such other forms of subsurface fluid exploitation as oil pro¬duction and underground gas storage, tracing subsurface interpretations from the initial exploratory concept to that of fullest development. Evolutionary changes in interpretation and their significance as applied to deep well disposal are stressed.

Jan 1, 1971

By A. ALLANORE, OLIVEIRA M. DE, D. CICERI, D. P. CHEN

The alkaline hydrothermal processing of K-feldspar rocks in an autoclave can be a pathway to synthesize a potassium fertilizer for tropical soils that is potentially cheaper and more efficient than traditional potash (KCl). When K-feldspar undergoes hydrothermal alteration in the presence of calcium oxide (CaO), it generates a complex mixture of calcium-aluminum-silicate-hydrate (CASH) minerals that incorporate K atoms stochastically in their structure. These atoms are subsequently released, as shown in a test-tube leaching test, indicating a possible uptake by crops. The relationship between the processing temperature and time in the autoclave for the hydrothermal reaction and the resulting mineralogy and elemental release are only partially understood and are investigated in this study. Elucidating that relationship is the key requisite for subsequent techno-economic analysis, and ultimately for the development of a fertilizer that can be considered as a feasible alternative to KCl.

By Aleksandar D. Bugarski, Dylan A. Ritter

The results of laboratory characterization of tailpipe emissions for three “clean” engines that meet U.S. EPA Tier 4 final emissions standards were used to assess the viability and effectiveness of repowering existing engines and powering new mobile equipment with those engines as a control strategy for reducing exposure of underground miners to diesel aerosol and criteria gases. The evaluated engines were representative of those that achieve the emission standards through implementation of various in-cylinder emissions control strategies, use of crankcase filtration, and use of three types of exhaust aftertreatment systems: (1) diesel oxidation catalytic converter (DOC), (2) combination of DOC and the full-flow wall flow monolith diesel particulate filter (DPF), or (3) combination of DOC, diesel exhaust fluid (DEF) based selective catalytic reduction (SCR) system, and ammonia slip catalyst (ASC). The study showed that the highest reductions in concentrations of diesel aerosols in underground workings, in terms of both mass and number, could be achieved if the engines, preferably in all power classes, are fitted with viable DPF systems. The use of U.S. EPA Tier 4 final engines equipped with DOC and DOC/SCR/ASC systems could help operators to considerably reduce mass, but not number concentrations of aerosols. The emissions of two of the evaluated engines, one equipped with DOC and the other equipped with DOC/DPF systems, were characterized by substantial secondary NO2 emissions that would limit the viability of those engines for underground mining applications. It appears that the catalyst formulations used in the exhaust aftertreatment systems of the “clean” engines marketed to the underground mining industry need to be formulated to minimize the potential for generation of secondary NO2 emissions. The results indicate that the engines fitted with viable SCR/ASC systems present a low-NO2 alternative. All three “clean” engines were found to have low CO output. Therefore, due to nuances associated with the use of diesel-powered mobile equipment in underground mines, special attention needs to be paid to the selection and potentially optimization of “clean” engines for underground mining applications.

Feb 1, 2025

By C. A. Holley

The generation of coal fines is a growing problem which has serious environmental and resource recovery Impact. Several methods of agglomeration are studied including the production of briquettes for the consumer market. Simplified process flow diagrams, "order of magnitude" plant capital cost and operating costs are presented.

Jan 1, 1986