Search Documents

By E. Siami-Irdemoosa, S. R. Dindarloo

Ease of excavation or rippability, also called diggability or excavatibility, is a critical decision-making parameter in the selection of both the overburden removal method and the required equipment in surface mining and geotechnical engineering projects. The most widely used method of estimating rippability is rock mass classification. Although there are different classification schemes in the literature, all of them have the two major limitations of sharp transitions at class boundaries and subjective uncertainties in decision making. In this study, the decision trees method was employed as a classification tool for estimating ground rippability, using the four rock mass parameters of weathering degree, uniaxial compressive strength, joint spacing and bedding spacing. The results were compared with those of the widely used method of diggability index rating (DIR) and a fuzzy-based DIR. The problem of subjective uncertainty was resolved in the proposed decision trees method, as the tree rules were derived automatically from the training data sets. Compared with fuzzy-DIR, a decision tree classifier is simpler, needs less computational time and is more appreciable by industry practitioners. Nevertheless, the proposed method is not flawless and, similar to both the conventional and fuzzy DIR methods, yielded poor estimations in particular instances. The limitations of the three methods are discussed.

Jan 1, 2015

By R. R. Klimpel

In this first report, we present a preliminary model based on the simple binary sys¬tem of component B occluded in a matrix of compo¬nent A, for the case where fracture planes can pass with equal ease through A or B. By assuming that the volume fraction of B in AB in the overall matrix is small, which is realistic for many prac¬tical systems, the problem is reduced to a one-¬dimensional treatment which is conceptually easy to understand. The model was programmed for Monte Carlo simulation, and an analytical solution also developed based on the assumption of zero or one mineral fragment per particle. Preliminary ex¬perimental confirmation using a synthetic "mineral¬-host matrix" of known amount and size of B in AB is presented.

Jan 1, 1983

By D. Butler

Lateral density changes in the subsurface cause a change in the vertical pull of gravity at the surface. By very accurate measurement of gravity and the practical application of common sense, a microgravity survey can sometimes detect natural or man-made voids, bedrock profiles, and geologic structures of engineering interest. This paper will give some practical guidelines for the application of microgravity surveying. Emphasis in many papers (Blizkovsky, 1979, Fajklewicz, 1983) has been on the anomaly size: herein emphasis will be placed on detectability and signal-to-noise ratios. First, some easy to use curves for anomaly valuation are adapted from Arzi (1974). Secondly, the predictable noise sources are discussed. Thirdly, representative models of abandoned underground workings are evaluated for microgravity surveying given the probable noise in the survey results.

Jan 1, 1988

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 T. P. Meloy

Like our wives, the comminution of brittle solids is easy to recognize but difficult to describe. However, describing it we must. Describing the fracture mechanism of brittle solids permits the eventual mathematical quantification of the results, process optimization and control strategies. This paper presents a physical model of brittle solid comminution that explains why the slope of the log-log size distribution curves have a slope of one or less in the smaller particle sizes. To develop the hypothesis, modifications of the Gaudin Meloy physical model are made. In brittle solids, comminution takes place by cracks propagating through the material. These cracks may bifurcate as they move. Cracks may terminate either on the original surface of the material, or on a secondary crack within the material formed earlier in the comminution process.

Jan 1, 1994

By V. I. Lakshmanan

Crystalline Flake Graphite is a strategic mineral. Since 1954 nearly all North American consumption has been imported from offshore. The Bouthillier Project in Quebec, Canada, is Orrwell Energy's bid to enter the market. Milling of flake graphite is considered easy, yet more problems have been encountered in flowsheet and plant design than in most other minerals. A fresh approach to existing technology was taken, giving results that are highly satisfactory. The key to graphite liberation without flake deterioration is found to be in autogenous grinding. In addition to producing marketable coarse graphite by such autogenous grinding, flotation and tabling, super purity fines can be produced using repeated regrinding, elutriation and flotation. This paper discusses the design of a 500 TPD plant based upon the results obtained from bench and pilot plant studies.

Jan 1, 1984

By Bok-youn Kim

Presently, mobile diesel equipments contributes a lot in improving the economical feasibility of underground mining and tunneling operations. Even in Korea, quite a large number of diesel equipments is being applied to the underground workings already. This paper introduced the production procedure, characteristics and evaluation technology on diesel particulate matter(DPM) that is known as a carcinogen For easy measurement of DPM using laser dust monitor, the conversion factor(K) to gravimetric concentration was acquired. The field measurement of DPM was conducted to make a comparison between locally manufactured on-road equipments and imported equipments specially designed for underground use. According to the Government regulation revised h 1996, it was learned that the critical pollutants among the diesel exhaust is DPM instead of NOx which have been considered as a critical pollutants.

Jan 1, 1997

By Brij M. Moudgil

Lack of understanding the major process parameters and inadequate scale-up factors have led to the belief that fundamental knowledge is not important for successful flotation plant operations. Flotation of simple and easy to process ores may not require a strong fundamental knowledge base for day to day operations. However, as low grade complex ores are mined and process control is integrated into flotation schemes, it is imperative for a plant operator to acquire a strong background in the basics of the flotation process at hand and/or have access to such a knowledge base at short notice. In order to meet the challenges of unexpected changes in the feed, reagent quality, water chemistry, physical, mechanical and hydrodynamic conditions, the flotation plant superintendent/chief metallurgist must have a strong background in the flotation fundamentals.

Jan 1, 1993

By Ed Van Eeckhout

The rockburst monitoring system at the Sunshine Mine has recently been improved to increase the certainty of burst locations and to output location results in a manner amenable to easy interpretation. Three methods of location calculation were used: a computer code provided with the hardware in-place (the MP-2501, a code based on the least-squares method (Blake et a1, 19741, and a nonlinear iterative code written by the principal author. The more accurate locations are given by the latter two codes, but still are only correct to within about 100 ft. This error is due to uncertainties introduced by the geologic and mining variations versus the assumptions made in the location codes. Software was then written to make two-dimensional plots of burst location by level, so management could monitor problems easily.

Jan 1, 1986

By William H. Langer

Nearly every community in the United States is dependent on aggregate (sand, gravel, and crushed stone) resources to build and maintain its infrastructure. Unfortunately, developing aggregate resources to meet societal needs causes environmental impacts. Most environmental impacts associated with aggregate mining are benign. Extracting aggregate seldom produces acid mine drainage or other toxic effects commonly associated with mining of metallic or energy resources. The most obvious environmental impact of aggregate mining is the conversion of land use, most likely from undeveloped or agricultural land use, to a hole in the ground. This major impact is accompanied by loss of habitat, noise, dust, blasting effects, erosion, sedimentation, and changes to the visual scene. Some of the impacts are short-lived, and most are easy to predict and easy to observe. Most impacts can be controlled, mitigated, or kept at tolerable levels and can be restricted to the immediate vicinity of the aggregate operation by employing responsible operating practices and available technology. The intensity of environmental impacts generated as a result of mining are determined in large part by the geologic characteristics of aggregate deposits (geomorphology, geometry, and physical and chemical properties). Mining deposits that are too thin, or contain too much unsuitable material, results in the generation of excessively large mined areas and large amounts of waste material. Mining aggregate can lead to serious environmental impacts in some situations. Some geologic environments such as active stream channels, slide-prone areas, and karst terrain are dynamic and respond rapidly to outside stimuli including aggregate mining. Some geomorphic areas and (or) ecosystems underlain with aggregate serve as habitat for rare or endangered species. Similarly, some geomorphic features are themselves rare examples of geologic phenomena or processes. Mining aggregate might be acceptable in some of these areas, but should be conducted only after careful consideration, and then only with extreme prudence. Failure to do so can lead to serious, long-lasting, and irreversible environmental consequences, either in the vicinity of the site or at locations distant from the site. Environmental impacts caused by irresponsible aggregate mining can compromise mining in an entire region.

Jan 1, 2001

By Peter G. Chamberlain

Many mining engineers considering in-place leaching for the first time are uncertain as to how to evaluate ore bodies for potential leachability. Evidence presented in this report emphasizes the critical role of permeability in such evaluations. Whether an engineer is considering leaching "tight" formations typified by the porphyry copper deposits of the southwest or the permeable uraniferous sandstones of Texas and Wyoming, permeability measurements are the keystone of any testing program. Permeability tests range from cheap and easy to highly expensive and sophisticated operations. Constant head, variable head, and pumping tests all have application in evaluating ore bodies for in-place leaching. Costs of these tests will not unduly deflate the pocket- books of most mining companies. The basic procedures for selecting and running these field tests-including preparing suitable wells--are reviewed for the benefit of newcomers to in-place leaching.

Jan 1, 1979

By Brad Grothen, Lok Home

The choice of TBM type is never easy, but it becomes especially challenging when faced with a hard rock tunnel with expected high water flows and pressure. Slurry Shield tunneling has a long history of being used in these conditions to minimize the risk, though this method has brought with it other risks along with cost considerations. At recent projects around the world, another method has been proven to effectively manage these project risks without utilizing Slurry Shield tunneling: Shielded, NonContinuous Pressurized (NCP)-TBM tunneling in rock with a comprehensive grouting program. In this paper, the authors will analyze the use of Shielded NCP TBMs at projects around the world as compared with slurry shield tunneling in rock under water pressure. Recommendations will be given in order to establish a clear picture of the optimal tunneling method.

Jun 13, 2021

By R. K. Sinha, B. S. Choudhary, Desh Deepak, A. K. Mishra, Hemant Agrawal, Shankar Kumar

Despite several methods (empirical, statistical and machine-learning tools) to calculate blast-induced ground vibration, it is not easy to predict and simulate blast vibration precisely under varying blasting loads and strata conditions due to complications in the blasting procedure. In this study, field blast data were simulated in Ansys software using explicit dynamics, and ground vibrations for 20 single-hole blasts were monitored. The densities of emulsion explosives were in the range of 0.9 to 1.15 g/cm3. In the laboratory, rock properties were determined from rock samples collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and density of the emulsion explosive were also determined and used in numerical analysis to know the ground vibrations at specific points. The results of ground vibrations predicted by the model were validated using field data.

By George A. Desborough

Marine black shales of Paleozoic age in the Western United States that exceed 10 weight percent organic carbon contain as much as 5,000 ppm vanadium, 1,000 ppm molybdenum, 1,300 ppm nickel, 600 ppm cobalt, 16 ppm silver, 7,000 ppm chromium, 18,000 ppm zinc, 280 ppm cadmium, and 350 ppm selenium. Depositional settings include: (1) continental-rise and marginal-ocean basins, (2) continental-shelf and foreland basins, and (3) cratonic-platform embayments. Most of these metalliferous organic-rich shales have not been examined for resources because of rapid weathering and poor exposures which preclude easy sampling of unoxidized rock necessary to determine actual concentration and residence of indigenous metals. Generally, the marine black shales of Paleozoic age in the Western United States are richer in metals than marine Paleozoic black shales in the Eastern United States.

Jan 1, 1982

By J. W. Leonard, D. A. Newman

By using physical and chemical means to increase the bulk density of newly broken coal freed from the mine face, the potential to improve coal mine productivity is significantly enhanced. It is estimated that by increasing bulk density, greater tonnages can be placed in fixed volume scoops and shuttles cars to improve production by as much as 10% to 20%. Such improved packaging to achieve new levels of volumetric efficiency might require only small and easy to implement changes to present downstream mining operations. Opportunities exist for improving broken coal bulk density from the moment of breakage, during transport across the continuous miner or loading machine, during discharge into the haulage unit, and after placement in the haulage unit. Physical/chemical methods for broken coal compaction in mobile, fixed volume units in underground operations are discussed.

Jan 1, 1990

By A. Exikis

Simulating a ventilation network of an underground mine can help in solving complex ventilation systems with many features, selecting proper fan specifications, location and settings. Early computer systems running simple network simulations were able to provide solutions to the most common and immediate problems regarding underground mine airflow. The more advanced systems available today can perform more sophisticated modeling and simulation of a mine?s ventilation network and present their results in a more understandable and easy to communicate form. This paper presents a ventilation network case study from an underground mine. All aspects of mine ventilation network modeling and simulation are discussed as well as the results from the simulation process. The algorithms and techniques used are thoroughly explained. Some useful guidelines for the application of ventilation network software are also provided in the text.

Jan 1, 2006

By T. H. Eyde

Worldwide production of natural zeolites during 2001 was estimated to be about 3.5 Mt (3.85million st). Construction and agriculture continued to be the major consumers. Estimated production in North America during 2001, including the United States, Canada and Mexico, was about 40 kt (44,000 st). In the United States and Canada, the zeolitic tuffs are ground, extruded or modified for use as adsorbents, desiccants, ion-exchange media and carriers. In Mexico and the rest of the world, the zeolitic tuffs are cut into dimension stone that is used in construction. Zeolitic tuffs are usually composed of the minerals clinoptilolite, mordenite or both. They occur in a variety of colors and are easy to cut and shape. And they have low thermal conductivity. This construction application is classified with dimension stone rather than with chemical and agricultural uses.

Jan 1, 2002

The global tunneling industry has many challenges, both technically and financially, with the latter likely to be a significant feature over the next few years. Many industries have ad-opted standard practices in order to overcome specific technical challenges, from which standard out-comes are anticipated. In tunneling, however, every project is unique so standardized practice is not easy. This requires original thinking and being open to adopting new techniques and technologies as they emerge. Sprayed waterproofing is a hot industry topic and a paper recently presented at the North American Tunneling conference not only discussed this methodology for achieving a dry tunnel but also how it can reduce build costs and construction time. Despite their being relatively few ?universal truths? throughout the tunneling industry, there is one opinion that appears to be shared by most in the sector, ?all tunnels leak.?

Jan 1, 2010

By Donald H. Dowlin

The design of a preparation plant for minimum maintenance and clean up requires both the skills of the Engineer and the practical experience of the Operator. From the initial flow sheet and preliminary design until the plant is completed and operating, each phase of the work must be thoroughly explored for simplicity, workability and high efficiency. It is the responsibility of the Designing Engineer to develop the plant around the basic flow sheet, selecting equipment and materials not only with regards to Initial cost but also required upkeep and repair.

Jan 1, 1962

By Leonard Sugin

The requirements of today's and tomorrow's markets led to a new generation of facilities which handles large tonnages annually, loading them into larger vessels, at higher rates, efficiently and reliably, with minimum labor input, and significantly greater attention to the environment. A great variety of products are handled, including various grades of metallurgical and steaming coal, coke, iron ore in its many forms, shapes and moisture content, phosphates and fertilizer products, bauxite and alumina ores, limestone, sugar and grains, cement and many other products. When we examine the annual tonnages involved in these movements the economic value of handling these products on a bulk basis can be readily seen. Although nearly all these products have been handled by continuous bulk conveyors for many years, recent governmental response to environmental concerns require a re-evaluation of previous procedures. Most air pollution and emission control regulations and ordinances have recognized several specific sources of pollution. Detailed regulations and requirements have been developed concerning smoke emissions, emissions of visible air contaminants and particulate matter from power plants, heating plants, refuse burning equipment, coke ovens, steel furnaces, kilns, and other industrial installations. Although fugitive dust is also an environmental pollutant it is governed by regulations that are more general and therefore, more difficult to apply. A general definition of a "fugitive particle" is any matter which escapes or becomes airborne from an operation or which is emitted into the atmosphere without passing or being conducted through a flue, pipe, stack or other structure designed for the purpose of emitting air pollutants into the atmosphere. This paper deals with the aspects of fugitive dust emissions as they apply to shiploading. Fugitive dust emissions control is important not only because of environmental regulations but also to prevent the loss of valuable product, reduce housekeeping, and reduce breakdown and maintenance problems to land and vessel equipment. The environmental controls for a belt conveyor system are those which will restrict the emission of fugitive dust particles and can be considered as follows:

Jan 1, 1977