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By Jean-Marie Deschamps

In an approach to the complicated study of bauxite from Les Baux de Provence it is necessary to consider the paleogeographical context of all the bauxites in southern France. These bauxites are of Karstic type, belonging to a metallogenic area extending from the Pyrenees Mountains to the Alpine Massif. Within this area each deposit does not always correspond to the same geological period. There are differing opinions regarding the origin of Karstic-type bauxite and a discussion of these various theories is beyond the scope of this paper. Bauxite of Les Baux, in Provence, was discovered in 1821 by the chemist, Berthier, near this picturesque village located in the region of Arles. It is Les Baux from which the name of bauxite originates. For a long time this bauxite was of no interest because of high silica 'and mediocre alumina content. Besides, the calcium carbonate content is somewhat high and is one of the main characteristics of Les Baux bauxite. The problem of exploration of the Les Baux deposit has been to prospect minable zones according to traditional norms where silica and carbonate are low.

Jan 1, 1977

By W. C. Goldberg, E. M. Frizzell

Monitoring slope displacement in open-pit mines can help predict collapses and prevent serious damage, injuries, and fatalities. Early detection of movement may indicate the need to modify slope geometry, initiate dewatering if the slope is wet, or consider artificial support measures such as cable bolting. Slope monitoring at the Berkeley pit was carried out with varying degrees of intensity and continuity for about 15 years. Some of the old mine records are still intact and accessible. Slope monitoring data can therefore be collected and published for the benefit of other mine operators. Because prediction of slope failures is empirical in nature, publication of several well documented case studies will be a valuable contribution to the industry. Background - Berkeley pit Open-pit mining of copper from the Berkeley pit, located on the east side of Butte, MT, began in 1955 and ceased in 1982. During that time, about 1 Gt (1.2 billion st) of material were removed to form a pit about 1.8 km wide by 2.1 km long (6000 ft by 7000 ft) at the rim, and 550 m (1800 ft) deep as measured from the high hill on the northwest side. From the south side, the pit only measures 365 m (1200 ft) deep. The Berkeley pit was first owned and operated by Anaconda Minerals Co., and subsequently by Arco. Following its closure in April 1982, the mine began to fill with water. Washington Construction purchased the property in 1986, and Montana Resources Inc. began mining to the east of the Berkeley pit in July 1986. Numerous instances of slope failure were recorded during the course of mining and several intensive geotechnical investigations were conducted in an effort to optimize the mine design. One of the last and most comprehensive studies was initiated in 1977. For purposes of geotechnical analysis, the mine was divided into nine design sectors on the basis of geologic conditions, geographic orientation, and economic importance (Fig. 1). Only two of these sectors - the concentrator and the southeast corner - are considered here. Material properties were obtained from several studies of samples collected from the mine and adjacent areas. The slope was monitored using standard surveying techniques to record the amount of movement in an area. The

Jan 1, 1989

By K. Oraee

Excessive emissions of methane from the coal seams can have a serious adverse effect on both safety and productivity of longwall coal faces. Mechanization of coal faces has increased production possibilities to the extent that normal ventilation systems may not be able to ventilate coal face areas in order to lower methane content in the air to within legal limits. Production increases may therefore be prohibited for this reason, especially in gassy seams. Methane drainage from the coal seam by means of long holes and before production starts can act as a useful remedial action. In this paper a two dimensional mathematical model has been produced. The model that is based on finite elements, simulates a methane drainage system where the resultant risk is linked to the coefficient of diffusion, coal permeability, holes pattern and the duration for which the seam is subject to drainage. It is concluded that methane drainage of this type can assist in achieving production increases in many coals seems, especially where high gas content is a virtue of the seam.

Jan 1, 2010

By BHAMIDIPATI S. SASTRY, KATTAMURI PAVAN KUMAR, ADITYA PANDEY

Several laboratory methods are available to determine the thermal conductivity of rocks, but most of them are complex and cumbersome. The present study explains the working principle of Lee’s apparatus, which is relatively simple, easy to fabricate and use, and provides consistent results. In the present study, thermal conductivities of sandstone cores obtained from an Indian coal mine are determined using Lee’s apparatus. An approach is discussed to determine the temperature gradient of sandstone specimens while cooling and is used to calculate thermal conductivity. The thermal conductivities of different sandstone specimens have values between 2.37 and 2.59 Wm−1°C−1. For different sandstone cores obtained from the field, properties including specific gravity, specific heat capacity, thermal diffusivity and porosity, along with thermal conductivity, were determined and highlighted in this study.

By Z. Rogovin

In order to develop more accurate procedures for scale-up and design of semi-autogenous-grinding mills through detailed mathematical models, a better understanding of the charge motion and rock/ball segregation is needed. To achieve this a 0.61 m (2.0 ft) diameter x 0.305 m (1.0 ft) length plexiglas mill was constructed as a scale model of a commercial SAG mill. Rock motion in the rotating mill was simulated using various sizes of ceramic balls. Quantitative measurements of dynamic angle of repose, water and slurry motion, holdup and size segregation of the charge were taken. In addition, a video-presentaiton (available to the public) was prepared to elucidate charge and water motion at various mill speeds, charge volumes, rock size distribution and flow rates.

Jan 1, 1985

By A. B. Seal, C. J. Bise

Excessive noise has long been a hazard in the coal-mining industry. Studies conducted during the mid-1970s and mid-1990s consistently show that hearing loss within the mining industry persists, in spite of regulatory requirements and sampling technology advances. When the U.S. Mine Safety and Health Administration's new health standards to protect miners from hearing loss took effect in September 2000, the potential developed to reevaluate sampling approaches with regard to noise-source hazards, such as task-based methods. This paper describes results from a Pennsylvania State University research project now being conducted at an underground coal mine. Each occupation was reviewed, and a list of tasks or processes performed by each was generated. Traditional personal noise dosimetry, static sound pressure levels and equipment sound mappings have been performed. Job tasks indicating the greatest levels of daily noise exposure and contributions to noise dose have been identified and will be discussed.

Jan 1, 2003

By J. Garretson

When mining accidents occur, workers often become trapped and/or incapacitated. Current rescue operations can be dangerous and too slow to produce favorable outcomes. Currently, no method exists for rescue crews to scout ahead at critical times to assess the situation. Sandia National Laboratories (SNL), through a National Institute for Occupational Safety and Health (NIOSH) sponsored program has developed the Gemini-Scout mine rescue platform. The Gemini-Scout was created to assist in underground mine rescue missions. It has been designed to go into potentially hazardous environments to assess the conditions (structural, air quality, temperature). In addition, it will enable two-way communications with potential survivors prior to human rescue teams being able to enter the area. The Gemini platform is a dual tracked-chassis design, which gives the robot excellent mobility in unstructured environments. The design includes a passive 2-degree of freedom joint between two identical bodies allowing for ±30deg of pitch and roll. In addition to the base mobility platform, the Gemini-Scout incorporates many other features to help it succeed in its underground mission. The electronics are mounted in explosion proof housings to ensure safe operations in hazardous gas environments. The platform is also able to operate in up to 18in of standing water with its elevated pan/tilt cameras for navigation. A four-channel video link and Two-way audio on the vehicle help to ensure located survivors can communicate with the robot operators. The platform also incorporates a Mine Safety and Health Administration (MSHA) approved multi-gas sensor to monitor air quality. SNL believes that this technology is broad enough to be appealing to other first responders, such as police, firefighters and medical personnel. Gemini could easily be fitted to handle earthquake and fire scenarios, and it could provide relief in currently inaccessible situations.

Jan 1, 2012

By David R. Maneval

The mining of coal in Alaska receives special treatment in the Surface Mining and Reclamation Act passed by the U.S. Congress in 1977 (PL95-87). Section 708 of the Act required that the National Academy of Sciences (NAS) perform a study of "Surface Coal Mining Conditions in the State of Alaska, In Order to Determine Which, If Any, of the Provisions of the Act Should be Modified with respect to Surface Coal Mining Operations in Alaska'. The special committee on Alaskan Coal Mining and Reclamation of NAS completed their study in 1980 and prepared their report (NAS, 1980). At this time, the Secretary of the Interior and the Congress have taken no special action with regard to either special regulations geared specifically to Alaska or to submitting special draft legislation to the Congress requesting amendment of PL95-87. The Alaska Department of Natural Resources (DNR) has drafted legislation which was submitted to and passed by the 1982 session of the State Legislature. The State regulatory agency has also drafted the requisite regulations necessitated by the amendments to the State's Basic Coal Mining Act. It is expected that by mid 1983 DNR will have applied for "primacy" to the office of Surface Mining, U.S. Department of the Interior (OSM). They will be submitting the amended State Law, the revised State Regulations and an operational plan as called for by OSM regulations. The presumption is that primacy will be granted to the State of Alaska under PL95-87. The Usibelli Coal Mine continues to be the only operational commercial mine for coal in the State of Alaska. It produced 7.26 x 10 kg (8 x 10 " T) of coal during 1981. The current mine was started in 1920 by Captain Lathrop, an early developer and pioneer in Alaska. It was continued by Emil Usibelli and was taken over after the death of E. Usibelli (in the 1964 earthquake) by his son Joseph Usibelli who is the current President of, the firm3 Their latest improvement is a 27.5 m (36 yd. )Bucyrus-Erie Dragline which handles most of the overburden removal. The coal is removed by a loader-truck combination. They are currently starting up the use of a unit train loading facility which handles forty cars every two hours. This loading system was a development necessitated by the Sun Eel Export contract. The Alaskan Railroad was a major cooperator in the development of the first unit train loading facility in Alaska.

Jan 1, 1982

By Michael Taylor, Thomas W. BoBo

Currently two of the most important characteristics of construction aggregates are (a) the particle size distribution (psd) and (b) the “shape” of the aggregate particles. The long established test methods and standards for these properties require substantial resources and most suppliers can take samples and conduct tests at intervals measured in days (psd) or even months (shape). Furthermore these tests require time: so the results are available only after material has been stockpiled or shipped. In the rare cases where problems are found the out-of-spec material has often been shipped to points unknown. There are substantial advantages to be obtained if the psd and other geometrical properties could be obtained from the material as it moves through the production processes and if the results could be reported back within seconds or minutes to Plant Control Managers. This paper describes a single on-line system used to evaluate production of crushed material in a production quarry. The system consists of an enclosure (containing the camera and lighting etc.) mounted over a production belt. Images are fed by fiber optic cable to a nearby control room where the data are analyzed; stored; displayed; and made available for integration into a process control system. Numerous forms of display can be created according to the needs of the producer. Once programmed by an automation engineer all functions of operation are fully automated. The system has permitted over 400 tests per hour with a feed back time less than 2 seconds. Sufficient geometrical measurements are made so that many different “shape” factors can be computed on a similar time scale. The paper summarizes the results from approximately 100 shifts of about 8 hours each and compares the imaging method with the current standard hand methods. Study of the data generated showed that, when combined with additional plant information, the system can be used to generate additional useful control information.

Jan 1, 2005

"What is your assessment of the minerals business?My experience with mining has been primarily in the coal sector until about 10 years ago, when I also became heavily involved in the aggregates and industrial minerals sectors. I have also had peripheral involvement through family and partners in the gold sector, with just enough exposure to gold to become fascinated. In 1994, I visited Ghana and considered the possibility of taking an expat assignment at a surface gold mine that had just been started.It is not news that the coal sector in this country has suffered tremendously in recent years. Especially hard hit is the central Appalachian region, where a number of factors combined have had a devastating effect on production, jobs and the economy. These factors include federal regulations affecting coal production and use, higher production costs and decreasing market share of Appalachian coal by the switch from lower sulfur coal in favor of lowercost, higher sulfur coal from the Illinois Basin, as utilities have installed scrubbers to comply with Phase II of the 1990 Clean Air Act Amendments. Nationally, the lower cost of natural gas has been a huge factor affecting coal use. In Kentucky, for example, which exports to other states around 70 percent of its coal, those markets are disappearing, as utilities close coal units in favor of natural gas. This is a structural change in the electricity market, and one that will become more pronounced as federal greenhouse gas regulations are implemented.We often hear the phrase, "the war on coal." While there are certainly a number of market factors affecting coal production and use, this phrase captures a different element that is all too real. The attacks have come from environmental activist groups for many years; from some in the media and, in the last few years, from a White House administration that believes strongly in alternatives to coal. Then, there really is an alternative to coal in the form of the previously untapped unconventional gas reserves that allowed utilities to move away from coal.Coal mining will continue in this country. In fact, it appears that our production is holding fairly steady at about a billion tons a year. And predictions that I have seen indicate this will continue for the next few years. What impact the Environmental Protection Agency’s Clean Power Plan will have beyond 2020 is another question.What do you feel is the future of the minerals industry - near term and longer term?Our society depends on the future of minerals in this country being strong. Near term, we are going through some of the typical cycles. Having also been involved in aggregates during the last few years, the business follows government infrastructure projects, such as highway construction and public and private sector development. Those sectors are heavily dependent upon government spending and a strong economy. Increased spending in those sectors, which appears to be on the horizon, should provide additional market shares for aggregates."

Jan 1, 2014

By P. Anciaux, T. Simpson

The competitiveness of the EU manufacturing industry has come to the forefront of EU politics. The systematic monitoring of developments and the review of the state of the competitiveness of economies and enterprises was identified as an essential component in this process. Work is currently being carried out within Enterprise and Industry Directorate-General in order to analyse the different factors that influence the competitiveness of the non-energy extractive industry. Such an assessment should help to identify policies and actions which could contribute to and enhance the competitiveness of the industry. Assessing the competitiveness and sustainability of the industry implies the need for reliable, consistent data. One important example of how this need is being addressed, is the development of sustainable development indicators (SDI) for the EU non-energy extractive industry. These seek to monitor the industry’s performance and provide a platform for openness and discussion. Work was started on the development of SDIs in 2000, and the first report was published in February 2004.

Jan 1, 2005

By J. A. Cremeens, D. D. Overton, J. C. Varnier

"Slope failures that occurred in 2008 and 2009 at the Pikeview Quarry in El Paso County, Colorado, USA were investigated using three-dimensional discrete element modeling methods. Large scale block sliding failures occurred along weak bedding planes that dip steeply into an excavation located at the toe of the slope. Several mining sequences at the toe of the slope were simulated to evaluate the effects of various degrees of extraction and backfill on slope stability. Slope stability back analysis was conducted using pre-failure and post-failure conditions to determine the joint shear strength properties. Laboratory testing was also conducted to determine intact rock properties. Three-dimensional discrete element analysis was uniquely applicable to this evaluation because it allowed representation of shear stress of the basal sliding surface and it afforded evaluation of several scenarios of extraction and backfill at the toe of the slope. INTRODUCTION The Pikeview Quarry is an aggregate quarry located approximately five miles northwest of Colorado Springs in El Paso County, Colorado, USA. The quarry has been operated by several owners since the early 1900s. The Pikeview Quarry has been a major source of construction aggregate for the Colorado Springs area for many years (MSHA 1986). In the 1950s, the site was mined by Peter Kiewit and Sons to provide limestone for the construction of the nearby Air Force Academy. A large scale slope failure occurred on December 2, 2008, which stopped mining activity at the Pikeview Quarry. A second, related slope failure occurred on September 13, 2009. The second slope failure was located immediately adjacent to the initial December 2008 failure. The objective of this publication is to discuss the three-dimensional slope stability evaluation. The causal relationships of slope instability are not within the scope of this publication. However, omitting the precursors to slope failure would limit understanding of the nature of the slope stability evaluation. The regional and local geology and the history of slope instability at the Pikeview Quarry aid in understanding these precursors. Two main failure mechanisms were hypothesized during the failure investigation to explain the triggering of the 2008 and 2009 large slope failures at the Pikeview Quarry. Both mechanisms are given equal credence in this publication. Quarry excavation was a key factor in the slope instability for both failure mechanisms. The objective of the three-dimensional model was to evaluate the effects of extraction and backfill at the toe of the slope with respect to slope stability. GEOLOGY Regional and local geology are both important factors in slope instability at the Pikeview Quarry. Geologic structure at the quarry is related to regional mountain building and basin development associated with the Laramide Orogeny and the Rocky Mountains. Lithologies at the Pikeview Quarry are also related to regional trends. Localized geologic features, primarily related to weathering and erosion, have also been major contributing factors to slope instability at the Pikeview Quarry."

Jan 1, 2017

By Neha Shukla, Nikhil Dhawan

The current study examines the extraction of rare-earth elements from trichromatic phosphor of discarded tube lights via baking processes. The Y2O3: Eu3+ (YOX) and BaMgAl10O17: Eu2+ (BAM) phases completely decomposed during acid and alkali baking with > 90% Eu and Y extraction. Prior, selective acid leaching of the YOX phase enhanced the acid baking process at a lower temperature (< 230 ℃). Feed acid baking showed a maximum 87% Tb, 36% La, and 17% Ce extraction at 500 °C, 0.5 h, 1 ml/g H2SO4, and alkali baking yielded 16.1% Tb, 86% La, and 73% Ce at 300 ℃, 0.5 h, 50 wt.% NaOH. The acid baking of the acid-leached phosphor yielded 72% Tb, 95% La, 63% Ce, ~ 95% Y, and Eu extraction at 300 °C, 0.5 h, 1.05 mL/g H2SO4. Lower Tb extraction during the acid baking of acid-leached phosphor can be attributed to the formation of Ba3Tb( PO4)3 and BaTbO3 phases. Insoluble Si3Tb5 phase formation and partial decomposition of CeMgAl11O19: Tb3+ (CMAT) phase in the alkali baking route leads to lower Tb extraction. The acid baking process is suitable for extracting Tb, Eu, and Y, whereas the alkali baking process is suitable for La and Ce. The thermal analysis of phosphor and flux interaction depicts that alkali baking is less energy-intensive than acid baking. In comparison, the one-step acid baking process and the two-step alkali baking process yielded desirable extraction results (87% Tb, total RE (rare earth) 78.5% and 50.4% Tb, total RE 59.3%). The product yield in the acid and alkali baking route of feed, acid-leach phosphor is 36%, 29%, and 39%, 28.2%, respectively, with ~ 98% mixed rare-earth oxide purity.

May 5, 2022

By V. K. Srivastava, T. Gupta, T. Ghosh

"In recent years, the demand for rare earth elements (REEs) has grown due to increasing demand and global supply shortage. The supply deficit of these critical elements has encouraged the search for new sources, with coal and coal byproducts as possibilities. Coals from certain parts of the world can be rich in REEs and can approach a total concentration of 1,000 ppm. Two Alaskan coal samples, from Healy and Wishbone Hill, were investigated for the effects of density and particle size on REE concentrations for three selected size fractions, and flotation tests were conducted on finer fractions. Additionally, bottom ash and fly ash samples from a power plant were examined for their REE concentrations. The results show that the upgrade potential for REEs on an ash basis from a whole-coal basis ranges from 2:1 for the Wishbone Hill samples to 4:1 for the Healy coal samples. Flotations of the finer fractions of the two coal samples, conducted under similar conditions, revealed higher concentrations of REEs in the tailings. Both coal samples had comparatively higher contents of light-group rare earth elements (LREEs) than heavy-group rare earth elements (HREEs). REE content trends for the power-plant products on an ash basis indicate that fly ash has slightly higher concentrations of both LREEs and HREEs than bottom ash. IntroductionRare earth elements (REEs), also known as rare earth metals, and their compounds are vital components in industrial, automotive, petrochemical, defense and medical applications. Dysprosium in combination with other elements is used in laser materials and nuclear control applications. Neodymium is present in magnets that are used in the manufacture of wind turbines and hybrid cars. Europium, terbium and yttrium are used in devices that have visual displays such as computer screens and laptops (Haxel, Hedrick and Greta, 2002; Bunzli, 2013). REEs pose fewer environmental problems of disposal and recycling than their conventional heavy metal counterparts (Haxel, Hedrick and Greta, 2002). They are key materials for radar systems, avionics, modern national defense and satellites (Cammarata and Sieradzki, 1994; Hedrick, 2010; Martin, 2010; Szumigala and Werdon, 2011; Cordier, 2011; Bunzli, 2013). REEs are often classified into light-group rare earth elements (LREEs) and heavy-group rare earth elements (HREEs). This classification is primarily based on the electronic configuration in the outermost shell. LREEs, ranging from lanthanum to gadolinium, have a single or no spinning electron in the outermost 4f shell while HREEs, ranging from terbium to lutetium, have paired electrons in the 4f shell. This difference in electronic configuration is responsible for the differences in physical and chemical properties of REEs."

Jan 1, 2017

By Thomas A. Wheeler

The reagents commercially used in coal flotation and their roles are reviewed and discussed According to their function the reagents are divided into often overlapping groups: 1. Collectors 2. Frothers 3. Conditioning Reagents Frothers have by far the largest effect on the amount of coal recovered They act not only in their traditionally accepted function of “bubble makers”, but in coal flotation they serve in a seldom acknowledged role of collectors. A lab flotation study on four samples of different coal ranks shows how these react to various frother families and proves that no froher is the optimum reagent for all types of coal. The advent of new technology in flotation equipment in the past decade has resulted in various novel designs of column cells, Jameson and Centrifloat™ cells, air-sped hydrocylones, etc. All should require special frothers or blends of frothers to meet their specific needs.

Jan 1, 1994

By W. S. Fyfe, G. Southam, T. J. Beveridge

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An invitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold(which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14%within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%)throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999

By W. D. Elston, A. E. McLaughlin, G. B. Hampton, W. L. Barham, J. F. Murphy, W. H. Cundiff, J. W. Mulloy, R. G. Breuer, J. W. Shaffer

Introduction Alumina (aluminum oxide) is the material from which all the world&apos;s aluminum is produced. In the Western World, all the alumina is made from bauxite by the Bayer process. In the nearly 150 years since aluminum was first isolated by Oersted, the metal has grown from a laboratory curiosity to a position of major importance in the world&apos;s commerce. In terms of annual production rates aluminum is first among nonferrous metals. Oersted&apos;s discovery-reduction of aluminum chloride with potas¬sium amalgam-was improved on by Ste. Claire Deville, whose so¬dium amalgam reduction of aluminum chloride led to the commercial production of aluminum in France in 1855. Ste. Claire Deville&apos;s method prevailed until 1886 when Charles Martin Hall and Paul T. Heroult each invented a process for the production of aluminum by the electrolysis of alumina dissolved in molten cryolite. The inven¬tion by Karl Josef Bayer in 1888 of an economical process for making very pure aluminum oxide (alumina) from bauxite established the necessary link between known ores and the Hall-Heroult reduction process. Bayer&apos;s work completed the scientific base-the ore bauxite refined to alumina by the Bayer process (U.S. Patent No. 515,895), the alumina reduced to aluminum in the Hall-Heroult cell (U.S. Patent No. 400,766--upon which today&apos;s aluminum industry is founded. Small-scale production of aluminum in the U.S. began in 1888 utilizing the Hall cell. By 1903, bauxite properties and a Bayer process refining step had been incorporated into the production activities. On this base the aluminum industry in the U.S. has grown at an annual compounded rate of 15%. Since 1946 the annual growth rate has been 10%.1 The rapid growth of the industry is the result of many factors among which are the existence of widespread bauxite ore deposits; a sound and economic production technology; and the properties of the metal-lightness, strength, ductility, good electrical and heat con¬ductivity, and pleasing appearance, which lead to ever greater de¬mands for aluminum in an industrializing society. At the inception of the industry, the only market that could be found for aluminum was in the production of cooking utensils. How¬ ever, the rapidly accelerating industrial and technological development of the Western World soon created new needs for aluminum, and today aluminum is marketed in a broad range of industrial, commer¬cial, and consumer applications. The principal uses for aluminum are:&apos; building and construction, 22%; transportation, 18%; electrical, 13%; packaging, 11%; consumer durables, 10%; machinery and equipment, 7%; other, 19%. The 1974 production of primary alumi¬num in the world was 14.5 million short tons, which at an approximate ingot price of 40¢ per lb puts a value of $11.6 billion on the industry product prior to fabrication. While aluminum is widely distributed in the earth&apos;s crust and is a major constituent of many rocks and soils, to date no method of extraction of aluminum from such nonbauxite material has been brought to commercial practice in the Western World. In the USSR alumina is produced by the complex processing of nepheline syenite, but elsewhere all commercial production of alumina is from bauxite. A brief discussion of recent developments and other processes for alumina is included in the subsection "Other Processes for Alumina," page 19-15. In early 1973, a major U.S. aluminum producer announced the successful development of processes for the production of aluminum from aluminum chloride. This achievement promises to exert a major influence on the future of the aluminum industry. In the initial com¬mercial application of this new technology, Bayer alumina will be chlorinated, and the aluminum chloride then reduced by electrolysis. Important claims for the new processes are lower energy requirements (one-third less than obtainable in Hall cells) and reduced labor costs. Capital costs are said to be no greater than for conventional plants. While the announced intention is to produce the aluminum chlo¬ride from Bayer process alumina, the new chloride reduction process will eliminate the other raw materials, carbon and fluorides, required by the conventional Hall cells. The electrodes in the chloride cell will not be consumed on the reduction process and the electrolyte will have, as the name indicates, a chloride rather than a fluoride base. 2. Bauxite Definition and Origin. Bauxite is a naturally occurring raw material composed principally of a mixture of one or more of the hy¬drated aluminum oxide minerals gibbsite (Al2O2 3H2O), boehmite (Al2O3 H2O), and diaspore (Al2O, - H2O), and impurities of silica, iron oxide, titania, and other various elements in trace amounts. It is an end or near-end product of chemical weathering. Depending on the amount of iron impurities, the color of bauxite varies from dark red and brown to pink to white. Some bauxite is finely divided, free digging earthy material, while other forms are dense and rocky, requiring explosives in mining. Many gradational forms exist. It is one of the most variable of mineral raw materials in chemical composition and physical appearance. It is generally believed that bauxite deposits resulted from intense chemical weathering of aluminum-bearing rocks or formations under tropical or subtropical conditions with alternating wet and dry sea¬sons. Topographic conditions were favorable for drainage and the in-situ accumulation of aluminum, iron, and titanium oxides. There was low to moderate topographic relief with a minimum of erosion during long quiet periods in earth history.2 The occurrence of bauxite is widespread and it has been found on all continents except Antarctica. Production was reported from 27 countries in 1974, at which time total world production was over 79 million metric tons. Of this production 76% was from seven coun¬tries-Australia, Jamaica, Surinam, Guinea, USSR, Guyana, and Greece-which ranked in that order of production. In Table 1 are shown typical compositions of bauxite from some

Jan 1, 1985

By T. O. Dauda, L. O. Ojo

One of the results of the Earth summit (The United Nations Conference) on Environment and Development - UNDP is the statement of forest principles. Others include: the Rio Declaration which is that the human beings are entitled to a healthy and productive life in harmony with nature; Agenda 21-for achieving sustainable development in the 21st century; the convention on biological diversity and the frame work convention on climate change. In the preservation of the biological diversity, Government at various levels took series of steps such as legislation, establishment of forest reserves including strict nature reserves, Forest guards, afforestation projects and others. Omo Forest Reserves is one of the Forest reserves owned by the Ogun state Government of Nigeria. It houses the Omo Biosphere Reserve (that is Strict Nature Reserve of International standard). This biosphere reserve is surrounded by buffer zones, which are meant to serves as protection for the biosphere reserves against encroachments. This study showed that the richest plot in term of species composition (that is plot 15 with the species frequency of 123) is almost the least diverse (with Simpson diversity index of 0.9127 which is 0.0238 higher than the least). It could also be established from this study that the diameter size class of trees with the highest frequencies are the lower size classes (5cm-10cm and 10cm -20cm). These results revealed a magnanimous encroachment on the buffer zones, which is an indication of bad status for the Biosphere Reserves as well as against the spirit of the sustainable use of the natural resources.

Jan 1, 2005

By D. P. Richards

Tunneling in carbonate sedimentary rocks such as lime stones and dolomites can be difficult when solution channels or voids are anticipated. Addressing the risk aspects associated with these formations can be done effectively through the Geotechnical Baseline Report (GBR) by properly characterizing the ground and ensuring that the Owner?s and the Contractor?s interests are represented and protected. This paper presents a review of tunneling difficulties in these rocks and includes a review of site investigations, geologic characterization, and presentation in the GBR. Key construction issues are also discussed, including appropriate excavation technology, mechanisms of face support and groundwater control, and quantifying grout takes.

By John W. White

Anthracite mine refuse, or culm dump material as it is sometimes called, is the waste material resulting from the sizing and cleaning of run-of-mine deep and strip-mined anthracite coal. It may also contain mine rock, carbonaceous shale, pyrite, and other debris from mining operations. This material is generally stored in piles or banks, some of which are over 100 years old. Many of the older banks contain a considerable amount of good coal, particularly in the finer size ranges, since these sizes did not have any particular economic value in the early days of anthracite mining. Today, the refuse material from a cleaning operation must be piled in an orderly fashion and in such a way as to minimize the tendency to ignite. There are well over 400 of these banks in the anthracite region containing over 1100 million tons of refuse located in the north-eastern part of Pennsylvania. The banks range in size from a few thousand tons of material up to as much as 13 million tons. Most of

Jan 1, 1972