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By J. Patrick Powers, Arthur B. Corwin

Modern improvements in hydrogeology make it possible to predict with good reliability the performance and cost of ground water pumping systems in many tunneling situations. The testing and analysis techniques are presented. Data from the Buffalo NY LRRTS (1978-1980) illustrate the successful application of the technique for tunneling in rock. Data from the Red Hook Interceptor Tunnel in Brooklyn NY (1978) illustrate the application in soft ground. The Red Hook project also illustrates concerns for the side effects from dewatering, such as ground settlement and damage to timber structures. At Red Hook protective measures included compressed air, artificial recharge and controlled dewatering. Given the uncertainties of the underground, the possibility of unexpected situations must be considered. A hard rock sewer tunnel in Atlanta, Georgia (1982) illustrates an unexpected problem, and the emergency measures used to solve it.

Jan 1, 1985

By Donald S. Clarke

The Umuna epithermal precious metal deposit has provided the target for a simulated rock geochemistry exploration program, directed at bedrock exposed in the drainage system of eastern Misima Island. A geochemical halo to the deposit is readily recognised in the mafic meta-volcanic country rock. This halo is defined by anomalous results for both major (K, Na, Ca, Mg) and minor (Au, As, Sb, Cu, Pb, Zn, Ba, Rb, Sr, Cs, Bi, Ga, S) element geochemistry, extending further than 1km from the deposit. Such halos are sufficiently extensive to provide adequate exploration targets in the search for epithermal mineralisation, complementing mineralogic and secondary media geochemical investigations.

Jan 1, 1989

By S. Shankar

Available literature on the effect of re-entrainment on overall airborne dust concentration in mine airways or the fundamental mechanisms of coal dust re-entrainment in mine atmosphere is scant. Therefore, as part of the Respirable Dust Center's ongoing research, a three part study was envisaged: study of the re-entrainment phenomena of anthracite and bituminous coal dust particles in a wind tunnel under the influence of varying air velocities; study of the same in the Lake Lynn Laboratory Mine of the USBM with both airflow and walking by personnel causing re-entrainment; and mathematical modeling and computer simulation of the re-entrainment phenomenon. In this paper, results from the re-entrainment studies in the wind tunnel and the Lake Lynn Laboratory Mine are presented. Further, the results from the wind tunnel studies are compared with the results from in-mine studies conducted at the Lake Lynn Laboratory Mine of the USBM. Comparing the results from the two studies it was observed that increasing air velocity increased the rate of re-entrainment, but increased time of exposure decreased the airborne dust concentration. Compared to same size particles, a mixture of sizes created more airborne dust concentration when re-entrained. It was also observed that contribution of airborne dust concentration due to airflow was negligible compared to the contribution due to walking.

Jan 1, 1995

By F. F. Peng, S. S. Peng, V. Z. Sun

A detailed study of ponding phenomenon relative to surface subsidence due to longwall mining was conducted for various surface stream conditions. Based on field monitoring, the stream-ponding process and three forms of stream water are described. Also discussed are the criteria of stream ponding and the influences on the ponding process by two key factors: the angle of stream flow and the change in the stream-bed gradient. A numerical (mathematical) model, which combines trend surface technique that describe the topographical features in the vicinity of a stream and the modified influence function, which represents the profile of the surface subsidence trough (or basin), is constructed to predict the formation characteristics of stream ponding in terms of location, boundary and accumulated water volume of migratory and stationary ponds produced by the stream-ponding process. Three cases are analyzed using the model to predict the interaction of the underground operations and the environmental impact due to stream ponding. The feasibility of various mitigative measures are assessed.

Jan 1, 1997

By C. M. Walck

The Rosebud district is located in the Kamma Mountains, southeast of the townsite of Sulphur, Nevada. Since discovery in 1989, LAC Minerals, in joint venture with Equinox Resources, has delineated a resource containing approximately 570,000 ounces of gold and 5,500,000 ounces of silver. The deposit is of the volcanic-hosted epithermal quartz-sericite type. Mineralization occurs in tabular zones in and along the hanging wall of the South Ridge fault, and in cross-cutting high-angle structures. Multiple stages of discontinuous stockwork gold-and silver-bearing quartz-calcite-clay veins cut variably clay-altered, silicified, and sericitized rhyolitic Miocene volcanic rocks.

Jan 1, 1993

By A. M. Elmahdy

An amphoteric collector was tested for dolomite removal from phosphate ore. The effects of some operating parameters and their significance on the flotation of dolomite were studied using statistically designed experiments. The parameters studied were impeller speed, pH and collector dosage. Analysis of the results showed that pH is the most significant parameter. Moreover, a concentrate containing 0.53% MgO and ~31.1% P2O5 with a recovery of ~ 90% can be achieved at optimum values of studied parameters, i.e., a pH of 12, an impeller speed of 1,000 rpm and a collector dosage of 2.5 kg/t.

Jan 1, 2007

By A. T. Iannacchione

Recent fatal injuries occurring during pillar retreat coal mining call for better identification of the hazards and recognition of risks. Ground control hazards associated with room-and-pillar retreat mining tend to intensify with depth, requiring extra precautions in the form of additional controls. In many locations these activities are further complicated by local complexities often associated with unique or novel circumstances, such as over-mining or under-mining. One technique recently studied by NIOSH, Major Hazard Risk Assessment (MHRA), may help mine operators to mitigate the risks associated with pillar recovery operations. The approach was trialed at two underground coal mines in southern West Virginia that are currently practicing pillar recovery. The first step in the MHRA process involved reviewing the segments or parts of the pillar extraction mining system and identifying associated hazards and threats to the operation. Some of the high risk hazards at these two sites included: ? Rock fall during pillar extraction covers equipment and injury occurs during recovery operations, ? Rock fall above the roof bolt horizon, potentially injuring ? workers and/or requiring recovery action, ? Rib fall under deep cover, potentially injuring workers, and; ? Strata instabilities associated with subsidence of the interburden due to simultaneously mining two seams in close vertical proximity to one another. The mines? risk assessment teams then considered each threat individually in order to systematically identify potential unwanted events. The top unwanted events were examined individually using structured risk analysis tools. The output from the process includes a list of priority existing controls for monitoring and auditing, and a second list of potential new controls. These controls consisted of: Examples of best practices, ? Enhanced communication, ? Implementing standard operating procedures (SOP), ? Protocols for emergency response actions, ? Effective layouts, ? Efficient monitoring, and; ? Successful audits. This paper documents the process as it unfolded at the two mines, and analyzes the strengths and weaknesses of the MHRA technique as it applies to pillar recovery operations. This work was part of a larger NIOSH research project. NIOSH was responsible for: 1) facilitating the risk assessment process known as Major Hazard Risk Assessment (MHRA), 2) documenting the risk assessment process, and 3) providing mine management with a written draft summary of the risk assessment process. The results of the risk assessment represent the thoughts and opinions of the individual risk assessment teams and should in no way be construed as an endorsement of the risk assessment output by NIOSH or the University of Pittsburgh.

Jan 1, 2009

A number of factors have resulted in the widespread use of computer simulation as a day to day tool in the mineral processing industry, as is the case in most engineering disciplines. A number of simulation packages, both steady-state and dynamic are now available commercially. The developers of such software face an enormous challenge in maintaining and improving the packages due to the complexity inherent in such systems. This problem known as the software crisis faces all developers of complex software. Object-oriented (OOP) and design is a methodology which has been developed to try and minimise this problem. The use of the OOP paradigm in the devlopment of simulation software for mineral processing systems is explored in this paper and it is found that OOP techniques have major benefits for the design and development of such software.

Jan 1, 1992

By J. Olsson

Introduction Stainless steel has by tradition been a common construction material for hydrometallurgy processes and the most common grades can be found amongst the ASTM 300-series, i.e. austenitic grades of type 304L, 316L and 317L. However, there are a number of new grades available today, which imply more cost effective solutions for those designing plants where good resistance to acids, containing the desired metal ions, often contaminated with chlorides and other halides, is the key issue. There are austenitic-ferritic or duplex grades having the same or even better corrosion resistance than the austenitic grades and approximately twice the strength, which enables design in thinner gauges, which in turn implies less weight and less cost. They have also excellent engineering properties, enabling fabrication of process equipment, machinery and different types of tanks. On top of that, they contain less nickel and molybdenum than their austenitic counterparts, which implies not only lower cost for alloying elements, but also a more stable price when considering the price fluctuations for these alloying elements during the last years. This paper describes briefly the family of duplex stainless steel and it presents a number of relevant corrosion tests where duplex grades have been compared with austenitic grades. The results have in several cases been verified by in-plant exposures in zinc and copper production plants. It also describes applications and experience of duplex grades within a variety of hydrometallurgy plants. Installations of highly alloyed austenitic grades will be described as well. The corrosion tests and service experience reported cover hydrometallurgical processes based on sulphuric acid.

Jan 1, 2007

By J. J. Schwoebel

Resource Enterprises Inc. (REI) is exploiting the coalbed gas resource by working in unison with active underground mining operations. At REZ7s pilot project at the Soldier Canyon mine, Carbon County, UT, RE1 has drilled nearly 15.25 km (50,000 ft) of horizontal in-seam and slant boreholes during the initial two years of drilling activity. Produced gas has been sold to a natural gas transmission company on a continuous basis since mid 1983.

Jan 1, 1988

By Francis Martino

There are numerous techniques and predictive models used by geologists and mining engineers to define coal reserves and plan mines. The traditional reserve estimation methods commonly used include the isopach, triangular, polygonal, inverse-distance weighting, weighted-moving-average, and trend-surface methods. Geostatistically-based estimation techniques are now being examined by many geologists and mine planners as a superior alternative to these traditional methods. With today's coal mine development costs often exceeding $100 million, and power generation $1 billion, it is logical that a technique that can indicate the degree of confidence associated with a reserve estimate (fuel supply), and thus also the degree of risk, is highly desirable to the coal producer, the financiers, and those desiring to commit to coal utilization under short or long-term supply arrangements.

Jan 1, 1983

By Howard Brown

High purity, high brightness limestone deposits in the San Bernardino Mountains and Mojave Desert region occur in upper Paleozoic carbonate rocks which are part of an upper Precambrian and Paleozoic sequence that unconformably overlies crystalline basement. The Paleozoic strata are divided into formations and members, and correlated with strata of the inner Cordilleran miogeocline. The region has been affected by multiple Mesozoic intrusive, contact, and regional metamorphic events. Structure is complex, and includes polyphase Mesozoic folding and thrusting, and complex Cenozoic structures. The area continues to be seismically active. High brightness (white), high purity crystalline limestone deposits are uncommon because their formation is dependent on several geologic processes which include; 1) depositional environment, 2) contact and or regional metamorphism, 3) folding and faulting, 4) uplift and erosion, and 5) preservation through geologic time. The complex geologic history of the San Bernardino Mountains and Mojave Desert region has allowed the formation of several large high brightness, high purity limestone deposits which are currently being mined or will be mined in the future. Specialty Minerals, Inc. (formerly Ptizer), Pluess-Staufer (California), Inc. and Partins Limestone, Inc. produce high brightness, high purity limestone from several quarries in the San Bernardino Mountains. These active mines combined with undeveloped deposits controlled by Pluess-Staufer in the San Bernardino Mountains, New York Mountains, and Bristol Mountains in the Mojave area, contain proven and or indicated reserves sufficient to sustain production through the 21st century Detailed geologic mapping, intimate knowledge of stratigraphy, recognition of complex structures, sampling, drilling and assay data, are proven tools in the discovery and delineation of high brightness, high purity limestone deposits in the San Bernardino Mountains and Mojave Desert region of southern California.

Jan 1, 1995

By T. Seal

Hydro-Jex© releaching was undertaken during the summer of 2010 at the Valley Leach Facility (VLF) at AngloGold Ashanti?s Cripple Creek & Victor Gold Mine. Several advancements to the technique were made in response to the technical design and operational challenges posed by the unique site conditions. New geophysical resistivity monitoring techniques were developed to monitor solution migration during the injections. These developments are presented along with discussion of gold production resulting from the project.

Jan 1, 2011

By Robert F. Baker

Neanderthal technology is a harsh and inaccurate way to describe modern underground construction and mining practices, but such an exaggeration helps to focus on a major problem or wasted opportunity of modern society. Why is it not safer to excavate in the underground? Why are the working conditions still so unfavorable? Why are urban freeways, shopping malls, warehouses, power plants, sewage disposal treatment plants, and similar facilities still constructed on the surface of the ground--because it is a better location? On the contrary, if underground technology made full use of existing knowledge, underground resources and space would be much more effectively used. And why is the technology so inadequate? Certainly, researchers and practitioners are aware of the shortcomings and are equally aware of problems that have to be overcome. One of the most important reasons has to do with the type of policy goals that society has set in the past. Policy makers may have agreed that improvements would be desirable but no serious commitments have been made--that is, there has been no major allocation of resources to advance these technologies. And yet, to bring about significant changes will require significant time and resources. The resources that are needed are far in excess of what industry can afford to invest, particularly since the pay-off may be far in the future. So the problem reverts to society in general. As long as society is willing to tolerate the present costs and safety requirements for recovering minerals and for constructing underground facilities, then the changes will be slow in coming. Until such time as society sees and desires the benefits

Jan 1, 1974

By Raymond A. Bradbury

A significant news item appearing in a coal mining journal in November 1969 stated simply that a Caterpillar D-333-CNA engine had received Bureau of Mines Schedule 31 approval. This item occurring at the time a new mining property in Martin County of East Kentucky was being prospected and prepared for mining, resulted in the manage-ment of Martin County Coal Corporation asking the question, "Why not use diesel equipment in our new operation?" Martin County Coal Corporation is part of the A. T. Massey Coal Company, Incorporated organization. The property being developed is on a 17,500 acre leasehold obtained from Pocahontas Land Corporation and lies in the Wolf Creek area of Martin County. The Norfolk and Western Railway Company built a 24-mile railroad into this undeveloped section of Kentucky to tap a huge reserve of steam coal. Duke Power Company is the customer who will take all of the production from Martin County Coal Corporation mines which ultimately is projected to be 2,000,000 tons annually. Four coal seams, all above drainage, are included in the lease. The Middle Coalburg and Stockton are being deep mined now and it is in those mines that the diesel haulage equipment was introduced. This paper will endeavor to trace the steps loading to the introduction of the first diesel-powered Wagner Mining Equipment Company ScoopTram in a coal mine in America. It will further elaborate on the features which make this unit a very versatile and useful utility unit as well as the safety features which are incorporated in the machine. The success of this first unit led to the placing of

Jan 1, 1972

In the estimation of recoverable resources, geostatistical techniques such as Multiple Indicator Kriging require a change of support correction to derive theoretical recoveries based on an assumed level of mining selectivity. The change of support models most widely used in practice entail model based generalized corrections either on a global or local basis. Examples include the affine and indirect lognormal methods. Change of support corrections derived empirically through short-scale conditional simulation realizations often show notable differences compared with theoretical corrections determined using model variogram parameters. The existing changes of support models are reviewed and an alternative method is proposed.

Jan 1, 1999

By V. F. Hollister

Although it is apparent that porphyry copper deposits may have formed in the Andean orogen from Permian time onward, commercial deposits thus far developed appear to have Cenozoic ages only. Following Chilean useage, the porphyry deposits are divided into either: (a) a stockwork, or (b) a tourmaline breccia model. Stockwork type deposits tend to occur on major strike-slip structures which may be either transcurrent or transverse faults related to plate movements, while the tourmaline breccia type may more frequently form independently of regional faults. Stockwork types may be conjugate fractures that intersect and ramify as a network of veins and veinlets, cutting altered rock, and genetically related to a major regional fault, or in other cases they may reflect the intersection of two large fault structures. Circular fracture patterns may more rarely occur in stockwork deposits in response to a specific intrusive. Tourmaline breccia types are characterized by circular and radial fractures genetically connected in some way with tourmaline breccia pipe development or an intrusive piercement that preceded it. Each structural model contains mineralized intrusive8 which have a close time-space relationship to ore and in each model, mineral paragenesis is similar, regardless of age or location in the plate. Also, each model contains the same type of alterntion halos (phyllic, argillic, prophllitic) as are developed in intru- sive centers in porphyry copper deposits found in North America. The potassic zone is exposed best in the older deposits. Examples of each type of deposit are illustrated, demonstrating the feature evolved.

Jan 1, 1973

By Brooke T. Mossman

Asbestos fibers are highly fibrous silicate fibers that are distinguished by having a large aspect (length to diameter) ratio and are crystallized in an asbestiform habit that causes them to separate into very thin fibers or fibrils. These fibers are distinct from nonasbestiform cleavage fragments and may appear as thick, short fibers which break along cleavage planes without the high strength and flexibility of asbestiform fibers. Since cleavage fragments of respirable dimensions have generally proven nonpathogenic in animal studies, little data exists on assessing well-characterized preparations of cleavage fragments in in vitro models. The available studies show that cleavage fragments are less bioreactive and cytotoxic than asbestiform fibers. © 2007 Elsevier Inc. All rights reserved. Keywords: Asbestiform; Cleavage; Fibers; Fibrous

Jan 1, 2007

"Metallurgical process development in greenfield projects must define the comminution flowsheet and establish the equipment sizes that are required to deliver the project design criteria. These are critical steps that heavily influence the financial performance of the project, requiring a detailed understanding of the ore properties of the project resources and the best practice methods to size comminution machines. This paper reviews current practices for determining the ore characteristics relevant to comminution circuit design. Particular attention is given to the design of sampling and testing programs, and the methods commonly applied to size crushers and mills for conventional size reduction applications in mineral processing. IntroductionMetallurgical process development in greenfield projects requires the selection of a comminution flow sheet and must establish the equipment sizes required to deliver the project design criteria. This necessitates a detailed understanding of the ore properties that define the project resource. For brownfield projects the same objectives may apply for plant expansions, or the project objective may be simply to define the capacity and operating cost of an existing facility for a new ore source. The process development phase in either instance will typically comprise the following key activities:• Geometallurgical classification and sampling of the ore deposit or deposits.• Determination of comminution energy requirements.• Benchmarking similar projects.• Identification of flow sheet options.• Equipment selection and sizing.This paper is concerned specifically with process development testing and will as such focus on the first two activities on the list: sampling and testing of the deposit. The discussion will focus on testwork programs to support the design of comminution circuits commonly in use in mineral processing today, specifically crusher, tumbling mill and stirred mill technologies.It is important that any testwork program is designed giving consideration to the types of flow sheets that are viable for the project, and the data that will need to be generated to support the final equipment sizing. Designing a testwork program to only provide information about one particular type of flow sheet will not allow sufficient information to be generated for a rigorous trade-off analysis of options, and may therefore preclude financial optimization of the project. Testing programs should be designed to collect sufficient data to ensure that any backtracking at a later stage to fill in missing information is minimal."

Jan 1, 2016

By G. Van Weert

Separation of minerals by shape has received little attention, since minerals normally do not break into different shapes during crushing and grinding. However, comminution of consumer wastes generates opportunities for novel separations based on particle shape. For instance, ductile plastics are broken into longer curved shapes, whereas brittle plastics yield angular particles. Using spouting beds for particle separation in water requires controlling the spout's instability. The preferred geometry for such redesigned spouting beds is reported. Plastic cylinders, discs and spheres were separated as a function of rising water velocity and amount of particles in the system. By using 5 mm particles, differences in settling behavior could be video recorded.

Jan 1, 1999