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By Parris A. Lyew-Ayee

This paper is the first preliminary report on the bauxites and terra rossas of the Caribbean. It concentrates on the islands of the Greater Antilles, and for reference purposes the Yucatan Penin- sula is included. At this point, observations made in Jamaica, Haiti, and the Dominican Republic are compared with reported information on Puerto Rico, the Bahamas, Cuba, the Cayman Islands, and the Yucatan Peninsula with regard to occurrence, as well as physical, chemical, and mineralogical composition. From this, an attempt is made at classifying the types of bauxites in the Caribbean, indicating the best reserves estimates, and the process ability of these bauxites. Some suggestions are also provided to fuel the controversy over the likely source material(s) or origin of the Caribbean bauxites.

Jan 1, 1984

By Spencer R. Titley

The subject of this lecture, a late century perspective on porphyry copper geology, is one of current interest and importance as the search for these ores remains intense. It is presented in the belief that an appreciation of our present understanding of the subject requires it to be viewed historically, thus providing a basis for evaluating appropriate directions for con¬tinued study. At the outset, it is important to note that the technology of mining and extractive metallurgy has developed ore from these low grade orebodies, starting with D. C. Jackling, and has continued to create them as copper grade and price have diminished. But the continued search for them is a geological problem that responds to growing expectations of people and societies; exploration based upon ever increasing knowledge of the habits of the ores has been very successful. This is the story of evolution of geological thought and practice in porphyry ore search across an interval of time beginning with the bulk mining of "low grade copper ores at Bingham and ending with late Century concepts. "How did we get here?" The lecture concerns the ideas of many different people. The ideas and events discussed reflect a bias on North American thought, where the great low grade orebodies were first recognized as such and where many of the basic geological ideas were developed. A very great number of geologists have contributed to this understanding. In no sense is it meant to minimize the contributions to the story that have evolved in the study and mining of ores of the Andes, whose development and expansion has been nearly synchronous with that in North America - nor to minimized comparable contributions made in the late century from studies of the newer discoveries of deposits in other regions, especially the southwestern Pacific regions. In expansion of this topic, I have found that many important concepts are marked by appropriate publication but some are not, or I have not been able to discover documentation. Many notions appear to have become conventional knowledge without publication, mostly being geological viewpoints developed synchronously from similar observation. Thus, apologies are extended in advance to those whose work I have might have missed and to those unknown to me whose unpublished ideas may have seeped into the pool of common knowledge without appropriate recognition. . The analysis here addresses events of two time segments, an older one extending from the developments at Bingham in the early 1900s through the Second World War, ending about 1950; the second period extends from that time to the present. This separation is seen in Figure 1, which traces numbers of publications through the period as extracted from some 700 publications, again with a North American bias, from an annotated bibliography of porphyry copper geology in preparation. During the early period, exploration was "immature" in North America, that is, geologists looked for new districts and sites of the deposits. Outcrops were sought that carried the signatures of former mineralization and regional controls related to structural geology were closely studied. In the later period, North American exploration had "matured" into a study of districts, rather than a search for them. As the studies of these ores intensified during the younger period concommitant with increasing demands for the metal, they did so with a broadened understanding of some habits of occurrence, of hydrothermal alteration, mineral zoning, petrology, and geochemical and geophysical signatures. Outside of North America, search remained "immature" but closely related to the

Jan 1, 1997

By N. K. Riddle

In many mines, it is typical to stockpile material for milling based either on analyses from exploration and blasthole drilling, or on the observation and judgment of experienced personnel. New analytical instruments make it possible to perform multiple, rapid analyses of as-mined samples at or near the mining face, so that sorting into stockpiles can be much more accurate. Using data and operating practices from a phosphate mine, a model was developed to simulate the function of analytical instruments in ore-grade control and ore stockpiling. With this model, it is possible to determine the recommended sampling points and sample frequency to obtain the desired confidence limits on the stockpile analyses.

Jan 1, 2003

By Winfield G. Wright, Philip L. Verplanck, Douglas B. Yager, Dana J. Bove, M. Alisa Mast

The upper Animas River watershed is affected by metal-rich drainage from abandoned mines and by natural weathering of mineralized bedrock. To investigate the importance of natural metal sources, surface waters were sampled in a minimally mined but intensely altered area of the watershed. Water chemistry was strongly controlled by the degree of bedrock alteration. Propylitically altered rocks, which contain calcite, produced neutral waters with low metal concentrations, whereas quartz-sericite-pyrite alteration was characterized by acid-sulfate type waters with high metal concentrations. A mass-balance approach was used to estimate natural metal sources, which accounted for 56-905 of the dissolved metal load discharging from the study area

Jan 1, 2000

By L. A. Taylor, R. O. Colson, D. S. McKay

The production of oxygen on the Moon utilizing indigenous materials will be essential for successful lunar colonization. Several processes have been put forth to accomplish Lunar Liquid Oxygen (LLOX) generation. The schemes that have received the most study to date involve: 1) Reduction of ilmenite (FeTi03) by H2, CO, CH4, CO-Cl2 and Cl2, plasma. 2) Molten silicate electrolysis, both unadulterated and fluoride fluxed. 3) Several others, including H, reduction of glass, carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reduction of ilmenite and molten silicate electrolysis processes have received the most study to date. They are both feasible schemes and have various pros and cons, including their feedstock requirements. However, all processes should be addressed at the onset of LLOX research. This paper reviews several of the most studied and feasible processes for winning oxygen front lunar materials. There is an obvious need for more experimentation and study.

Jan 1, 1994

By Thomas E. McNider, Robert C. Howell, J. W. Stevenson

As of the end of October, 1990, there have been eight spontaneous combustion heatings reported to the Mine Safety and Health Administration (MSHA) at the No. 5 Mine. A reportable heating is defined as one with elevated surface temperatures of the strata greater than ll°C (20°F) above the ambient. The first heatings occurred in November, 1986. The last three heatings were located near the start line of "K" Longwall Panel in the southwest where mining had begun on May 21, 1990. All of the heated areas had been at the time of detection, or were sometime areas of high ventilation pressure differentials or high air velocities. All of the heated areas are in an expanded seam with associated, extensive floor heave which is characteristic of all of the expanded seam thus far exposed by development mining in the No. 5 Mine. Jim Walter Resources, Inc. submitted a plan to MSHA which would reduce the potential for spontaneous combustion at the No. 5 Mine by reducing high air velocities and high pressure differentials in the gob. These two parameters are the dynamics which feed oxygen to the pyrite, thus initiating the oxidation process which can lead to spontaneous combustion. No. 5 Nine operated under this plan for 29 shifts before mining on the longwall was stopped by MSHA and the Spontaneous Combustion Control Plan revoked. This paper briefly details the geology of the expanded seam and history of the heatings. It also gives a retrospective view of the operation under the Spontaneous Combustion Control Plan and reasons why it was revoked by MSHA. Currently, knowledge of the reaction process of the footwall coal seams at No. 5 Mine and other potential spontaneous combustion seams in the United States is limited. There are techniques used in the United States and other countries to minimize the potential for heatings in spontaneous combustion prone areas. The No. 5 Mine has attempted to utilize this current technology. However, in deep, gassy mines the problem is complex.

Jan 1, 1991

By R. Q. Honaker, D. Tao, D. Taulbee, B. K. Parekh

A significant amount of energy exists in the waste generated by the coal and timber industries. In the coal industry, the energy loss is mainly due to the discharge of fine coal to the waste impoundment. Despite the fact that the fine coal has the greatest cleaning potential, dewatering, handling and transportation concerns prevent its use as product in many cases. Likewise, the sawdust generated from wood production has energy value and is used as industrial boiler fuel when the transportation distance is relative short. However, wood waste is often discarded into cumbersome landfills due to uneconomical transportation alternatives. Recent research found that these two waste materials can be combined to provide a high energy fuel of around 13000 btu/lb that can be easily handled and transported to end users.

Jan 1, 2004

By Keith S. Liddell

Gold in many ores occurs in sulphides, which, if the gold is finely disseminated, renders the ore refractory and therefore not amenable to the simple process of milling and cyanidation. Traditional methods of treatment of these refractory ores is to produce a sulphidic flotation concentrate which is roasted to form a porous calcine from which the gold is recovered by cyanidation. The roasting process imposes a constraint of a minimum sulphur grade of the concentrate on the flotation plant, which may lead to a lower gold recovery being achieved in the flotation section. Thermal decomposition of the concentrate by roasting means that the sulphur contained therein has to be treated and disposed of in an environmentally acceptable manner; and, if arsenopyrite is present in the concentrate the environ- mental aspects will be worsened. It has long been recognized that finer milling of gold-bearing materials improves the liberation of gold, especially when the gold particles are very fine. After extensive laboratory and pilot plant investigations (Liddell, Patents), a suitable mill has been developed for the mining industry by Metprotech, which is capable of producing very fine grinds (down to 90 percent passing one m if necessary). In the course of the investigations it has been found that a large number of gold-bearing materials are amenable to fine milling. A specific advantage that fine milling of sulphidic materials has over oxidative processes such as roasting and bacterial leaching is that the sulphides are not decomposed and there is therefore not a sulphur disposal problem. Furthermore, the milled sulphides can become a future sulphur feed source, and can be reclaimed if necessary. A further feature of the Metprotech process is that it is possible to add cyanide to the mill feed

Jan 1, 1988

By T. A. Oberhellmann

The Wobbler Feeder is a comparatively new materials handling and separating device. It is essentially a materials separating or scalping machine, particularly adaptable to separation of oversize particles from mine-run ore and to the separation of oversize materials from overburden, where the removal of oversize materials is necessary, as is the case in conveyor stripping. In construction, the Wobbler Feeder is simply a set of transverse bars of manganese steel, or other wear-resisting alloy steel, each having an elliptical cross-section with the major axes of adjacent bars displaced by ninety degrees so when rotating in unison, the pre-determined space between the bars remains constant.

Jan 1, 1959

By C. Ptacek, D. Hiller, J. L. Janbor, H. Mccreadie

Between 1991 and 1994, metallurgical residues from a pressure-oxidation autoclave at the Campbell Au-quartz mine at Red Lake, northern Ontario, were neutralized with dolomite-rich flotation tailings and were deposited in a polyethylene-lined disposal area. Mineralogical analysis indicates that most of the As occurs as a crystalline ferric sulfarsenate, and some is associated with Fe oxides and with K-H3O jarosite. Field pore-water geochemical data from 1994 and 1995 showed increases in Fe(II) and As(III) concentrations, suggesting that the sulfarsenate and jarosite are dissolving; none of the discrete As phases included in a thermodynamic database limit dissolved-As concentrations, and these concentrations may continue to increase. These results demonstrate the potential for Fe and As loading through groundwater systems.

Jan 1, 1998

By J. A. Herbst

Mineral liberation modeling can be traced back to the early work 0fA.M. Gaudin up through more recent population balance modeling by R.p. King, J.A. Herbst and G.T. Adel. A more micro-scopic look was taken at the University of Utah in the form of the J.E. Sepulveda and J.D. Miller Pargen model which permits the creation of an arbitrary shape, multiphase particle made up of discrete grains. Recent work on image analysis and tomographic analysis by J.D. Miller and C.L. Lin have laid the experimental ground work for model validation, but until now it hasn't been possible to include the necessary physics of the particle stressing process to allow the development of a 'ffirstprinciples"mode1 which does not presuppose a "mode” of liberation (e.g., random or by detachment). Recent developments in discrete grain breakage (DGB) modeling now make a generalized physics based model feasible. This paper describes current work that is being done to develop a physics based discrete grain liberation (DGL) model. Two-dimensional and three dimensional simulation results exploring the effects of particle size, phase properties and loading type are presented. Relationships between energy based liberation efficiency, degree of random liberation and material properties are identified.

Jan 1, 2005

By M. A. Chandler, G. T. Adel, J. N. Richardson, E. C. Gutierrez

A rapid, bench-top analyzer has been developed to determine P2O5 content and CaO/P2O5 ratio in phosphate ores. The analyzer utilizes a portable computer equipped with a frame grabber to measure the reflective intensity (gray level) of phosphate samples placed in front of a television camera. P2O5 content is related to the average gray level of the sample, while CaO/P2O5 ratio is determined from the amount of bright material present. The sensor is currently being used to analyze flotation concentrate samples at Texasgulf's phosphate operation near Aurora, North Carolina. Sensor development along with results from laboratory and in-plant testing are discussed.

Jan 1, 1993

By Daniel H. Knepper

Estimating the lithologic composition of gravel deposits for aggregate quality using standard field and laboratory techniques is costly and time-consuming. As an alternative, digital geologic maps and elevation models may provide a means for predicting the lithologic composition of channel and terrace deposits. Digital geologic maps can be used to evaluate the distribution of map units: their geomorphic setting, and the physical properties of the gravel source. To test this concept, the lithologies and topography of the upper drainage basin of the Big Thompson River along the Colorado Front Range were used to examine various factors that may control the final lithologic composition of channel and terrace gravels downstream. The simplest factor is the area of each of the map units in the upper drainage basin area, which can be easily measured from the digital geologic map. The percentage of each map unit within the total area provides a estimate of the pro- portions of each map unit that might be expected to occur in the downstream gravels. Published estimates of the hardness and durability of each map unit were used to calculate physical property-weighted areas; these areas are an estimate of the potential of each unit to be eroded and transported as gravel-sized particles. The areas of each map unit at 1-kilometer intervals from the drainage basin exit point were used to calculate a distance-weighted area for each map unit. For this study, a simple inverse relationship (area/distance) was used for distance weighting, but a more complicated distance function may ultimately be required. The topographic setting of exposed rock units should exert a significant influence on whether material will move slowly or rapidly through the drainage system. Two topographic factors were examined: gradient and slope. A simple gradient between map unit occurrences and the exit point of the drainage basin was used to calculate a gradient-weighted area estimate for each map unit. The slope-weighted area estimate uses the slope steepness (in degrees) in the immediate vicinity of each map unit occurrence as a measure of the tendency of material to begin moving into the sediment transport system. The primary intent of this study was to test the concept of using digital geologic map and elevation images to estimate gravel composition, rather than actually producing a useful analysis of a drainage basin. Each of the controlling factors was examined independently to gain an understanding of the magnitude of the effect of each factor. Ultimately, a comprehensive predictive model will be constructed using a combination of the various controlling factors.

Jan 1, 2001

By Christopher J. Hall

It has been known for a long time that summing pressure drops and rises due to friction, shock, fans and natural ventilation is incorrect. In fact, lost works and works should be summed. In spite of this, the traditional method of finding a fan/system operating position has been the H/Q Curve. This paper presents (lost) work/m curves, progressing from a single fan moved around the system to include natural ventilation work, and fans in a series, parallel and series/parallel. The solutions obtained graphically are substantiated by dry air thermodynamic solutions, and the traditional solutions are shown to be in error. This method of solving problems is particularly useful when moving fans around the system, and essential in series/parallel and series situations with substantially different fan densities. The dry air analysis is employed because of its simplicity. Real air, with evaporation and condensation, will react somewhat differently, and one should use real densities (i.e.[l + w +w]/va ) when using this method. One source of error when applying this method to real air, although probably not major, will be investigated in a subsequent paper. Friction and shock losses are proportional to the square of the mass rate of flow, leading to the typical parabolic system curve. However, the unbalanced water stuff potential energy term, on a unit mass basis, is substantially independent of the mass rate of flow. It is possible that this could be handled as a negative natural ventilation work.

Jan 1, 1987

By A. Arik

1his paper presents a modified ordinary kriging technique referred to as the "Nearest Neighbor Kriging" (NNK). The method is a simple and practical tool to use when the ordinary kriging (OK) results are unreasonably smooth, especially when estimating recoverable ore reserves for deposits with skewed grade distributions. NNK is robust and globally unbiased like OK. However, it is more advantageous over OK because it can control some of the smoothing and conditional bias which have been the major pitfalls of OK in many grade estimation cases. The paper details the methodology of NNK and its application to a gold deposit.

Jan 1, 1998

By Sergey G. Pushkin, Eugeny L. Schastlivtsev, Anatoly A. Bykov

Three years ago the authors and a group of assistants began to develop a GIs-system for integration of comprehensive eco- logical information to be linked to geographical maps of Kuzbass region. And now we have got the working system and some first results that the present paper deals with.

Jan 1, 1996

By S. Orr

Flow in heaps and dumps is a two-phase flow phenomenon, though for many applications it could be simplified as unsaturated flow. Unlike saturated flow (typical of ground water flow), where permeability is independent of other hydraulic parameters, unsaturated flow permeability depends on the degree of saturation and/or on capillary pressure. Several recent field studies suggest that flows in heaps and dumps tend to concentrate in preferred pathways, bypassing much of the ore. Different preferential flow phenomena are triggered, promoted and influenced by different heap structures, by pretreatment, by the composition of the leach solution and by application rates and schedules. The structure of heaps and dumps is determined and affected by every stage of their construction -from blasting to crushing to conveying and stacking of the material. History of heap construction and operation combined with monitoring, mapping and certain field tests can reveal patterns of flow and transport in a given heap and can shed light on the physical mechanisms behind it. Such insight can provide a first cut on heap leaching enhancement by either eliminating or bypassing physical barriers to flow and leaching. Based on the understanding of the heap structure, advanced flow and transport models can be constructed and further enhance the insight. This insight is essential for understanding cause and effect and can provide a basis for decision making. Further, based on the physically-based models, an intelligent control agent, such as MRDS1, can learn and build a self-learning representation (or a model) of the complex heap leaching system, followed by dynamic optimization and planning of heap leaching and heap rinsing.

Jan 1, 2003

By A. B. Samaddar

A prototype automated mapping and spatial information management system has been developed, and illustrates how a powerful map manipulation capability and a comprehensive display system can be combined using both raster and vector mapping: The concept of a mapbase and information retrieval mechanism, query language as well as text and graphical menus, is introduced. The Geographic Information System (GIS), which has been built around a system for storage and retrieval of spatial and textual data, allows interaction with geographic space represented on a displayed map. The prototype is demonstrated using maps and information of an open pit mine.

Jan 1, 1989

By Yun Bai, Ang Chen, Xiangdong Hu, Yanfei Zhu, Gang Li

"It is well known that tunnelling involves a high degree of risk. Conventional risk management only evaluates risks and chooses mitigation measures before the start of a project. However, mitigation measures also introduce risks, which are ignored in the conventional risk control process when choosing different measures. The Multiphase Risk Management Method (MRMM) takes the risk of mitigation measures and dynamic risk control into consideration. This paper introduces this new method and provides a flow chart for better understanding. A case study of the MRMM is given based on Ningbo Metro Line 3, the first quasi rectangle shield tunnel in China. INTRODUCTION Tunnelling itself is generally complex and involves a high degree of uncertainty (Huang, 2006; Thompson and Thompson, 2006). In recent years, several metro tunnel projects in China have been involved in accidents (Wang, 2006; Gong and Zhang, 2012).As a result, Chinese tunnel engineers are paying more and more attention to risk management in tunnel projects (Xiao-lin and Ping et al., 2009; Zhong and Jia et al., 2014), and scholars around the world have put forward many management processes. Existing risk management mainly focuses on a particular stage of a tunneling project. Tunnel engineers or other project parties usually carry out risk assessment and set up schemes or choose mitigation measures before a project begins. The risk from this initial risk assessment may be defined as the initial risk (Bai and Dai et al., 2013). This kind of managing process has been widely used for its simplicity and comprehensibility. However, this static theory cannot properly reveal the dynamic character of the risk during tunnelling. In addition, to reduce the risk from unacceptable level to acceptable level also calls for optimum measures. Therefore, the multiphase risk management method was proposed (Bai and Dai et al., 2013). The purpose of this paper is to introduce and develop the MRMM, and to provide a brief flow chart to illustrate the risk management process based on it. Finally, an example of the first quasi rectangle shield tunnel in China in Ningbo Metro Line 3 is illustrated. It analyzes the initial and secondary risk and sets up a risk control system."

Jan 1, 2016

By Mohammad Hossein Sadaghiani

"Construction of underground structures in urban areas is a very challenging work. There are generally two methods of construction, an open cut-and-cover and underground method. To eliminate the subsurface and surface disturbance and street traffic problems, underground method is preferred. The stress redistribution caused by underground excavation induces movements and deformation in the earth mass and ultimately at the ground surface. This is more pronounced in large space excavations. Generally pre-supporting system is used to control ground deformation and thus enhance its stability. In this paper an innovative pre-supporting system is presented. Concrete Arch Pre-supporting System (CAPS) is introduced in Tehran Metro in 2002. This method has roots in construction method of an Old Iranian small water tunnels, called Quanat. CAPS is an efficient method for stabilizing large span underground spaces constructed in shallow and soft ground. In this technique underground reinforced concrete elements are constructed around the proposed underground space prior to main excavation. This method is used successfully in over 50 large span underground structures in Tehran Metro stations and road tunnel intersections. CAPS has potential to be used to pre-support the large span underground spaces at any weak ground condition in an urban area.1. INTRODUCTION Underground subway stations can be constructed either by open cut-and-cover or underground construction. Due to the presence of subsurface utilities and street traffics in urban areas, underground construction is preferred to eliminate relocation of the subsurface utilities, and other urban disturbance. Underground construction in an urban area is a very challenging effort. The complexity of the work is more pronounced in a weak and shallow ground. The stress redistribution caused by underground excavation induces deformations in the earth mass and ultimately at the ground surface causing damage to adjacent structures. The need to control ground surface settlements in urban area is widely recognized and new construction methods are continuously developed. Settlements induced by underground excavation may cause serious damages to nearby structures and subsurface underground utilities, (Sekimoto et. al. 2001). In order to improve stability of underground excavation and reduce settlements, various ground treatment techniques are presented, Johnson, et.al., (1983), Carrieri, et.al. (2002), and Ocak (2008)."

Jan 1, 2016