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By Kai Nielsen

In underground mining coarse muck and large boulders lead to ineffective utilization of costly mining equipment, and extra expenses and delays caused by secondary blasting. Cost analysis in some Norwegian mines shows that these extra expenses may amount to 10% or more of total mine operating costs. A computer model has been developed for sensitivity analysis of underground longhole stope blasting. The basic idea of the model is : When increasing the blasting energy input and fragmentation costs, the fragmentation will be better. This will lead to cost savings for loading, hauling, secondary blasting and primary crushing. The blasting design giving the lowest overall costs will indicate the optimal practice. The model has been used with data from several underground operations in Norway. An example run with typical costs shows that the costs for drilling, blasting and secondary blasting are the most significant parameters in the optimization process.

Jan 1, 1986

By N. B. Aughenbaugh

Compacted, fine-grained soils, often referred to collectively as clays, are used as permeability barriers in many mineral engineering projects such as heap leaching, containment ponds, tailings disposal and earth dams. Source materials for these liners include a variety of sand, silt and clay admixtures. These exhibit dramatically different engineering properties when densified. Therefore, it is imperative to adequately assess and characterize any soils being considered for compacted liners. The permeability and plastic properties of fine-grained soils are reviewed with respect to the state of compaction as the water content varies. Because they are weak in tension, compacted clays are susceptible to cracking when subjected to differential flexural movements. Designs of compacted clay liners also must include an evaluation of their flexibility. That is the ability of a fine-grain soil to bend plastically without cracking. This paper will also discuss the importance of flexibility with respect to soil types, compaction effort, failure mechanism and testing evaluation to the performance of clay liners in preventing seepage of pollutants from a containment site.

Jan 1, 1991

By A. Bayer, T. Klopfer

"As a leading global strategy consultancy, Roland Berger Strategy Consultants firmly believe that the issue of sustainability is at the core of every business activity. Thus, strategies to enhance corporate sustainability (CS) are an essential cornerstone in the consultancy's approach to develop and implement new strategic concepts for the clients. In this paper, the authors conclude that innovation is the only solution possible to guarantee growth and welfare gains while achieving sustainable development. More efficient and effective ways are necessary to enable technical and social breakthroughs. To illustrate Roland Berger Strategy Consultants's vision on CS, four selected cases from the basic resources, energy and utilities sectors are presented. They demonstrate that the implementation of a CS strategy does not only refer to CEO spheres and are by no means just a moral justification for current business practices. Rather they show that the decision to opt for these new ways also opens up multiple opportunities."

Jan 1, 2005

By W. E. Horst

Raw materials and mineral products are crushed, ground, or pulverized for a variety of reasons. Some of the most important reasons for size reduction are: to liberate marketable mineral species from a matrix of commercial minerals and gangue, to promote rapid chemical reaction through exposure of large surface area, and to produce a material with desirable size characteristics for handling, utilization, and storage. Comminution processes are currently used on vast tonnages of raw material annually. In the mineral industries where mineral products and other solids are processed, the various size-reduction unit operations represent a major portion of the manufacturing costs. The comminution process is an expensive unit operation from the stand- point of both capital and operating costs. Power consumption is large, and the energy conversion to useful work is very small regardless of the size-reduction system. In energy terms, about 1% of the all electricity generated throughout the world is expended in crushing and grinding operations by the cement industry alone. Comminution is a general term for size reduction that may be applied without regard to the actual breakage mechanism involved. General type of size-reduction equipment include crushers, tumbling mills of various type, impact mills, fixed-path mills such as a roller mill, and fluid-energy mills. Some comminution machines accomplish

Jan 1, 1985

By M. J. Laurila

Utilizing data compiled from a drilling program and bulk samples taken from a coal reserve, flowsheet performance for a coal preparation plant can be calculated using a desktop computer. Sets of equations defining material balances involving coal preparation plant unit operations are employed to depict plant performance. Techniques are discussed for interpolating washability data and extrapolating size distributions and other critical data to expand on oftentimes limited sets of quality data to a useable data base from which projections can be made. Simulation of flowsheets can be done for a number of different conditions and configurations while still remaining in a limited working memory capacity of 32,000 bytes. Presented within this paper are several pertinent examples.

Jan 1, 1982

By A. K. Sheik, W. G. Pariseau

A small underground mine in northern Idaho was used as an experimental facility for studying the role of water in the analysis of mine-opening stability. Laboratory test data, borehole measurements and geological mapping assisted in the construction of a coupled finite element model of the rock mass. The model was used to make quantitative estimates of rock stress, strain and displacement changes and to make estimates of the water pressure and flow velocity changes that occurred during historical mining. Stope cuts and wet fills were included in the analysis. The stability of the crown pillars between stopes was of particular interest. The relatively low effective stress and high rock-mass strength showed that water pressure changes were of no great consequence, which is in agreement with experience. The computational tools used in the analysis may be applied to other wet mines with appropriate changes to site-specific data.

Jan 1, 2002

By Alfred A. Roetzer

In several sections of the country new demands are being brought bar cement users. Among these the demand' for truck shipments; and palletized loads present new problems that do not lend themselves to sample solution. In fact these demands have far-reaching effect in the way bagged cement might be marketed. Early solutions of palletized truck loads filled from existing packing and loading facilities have resulted in' slowdown in packing, additional labor and space for palletizing, considerable experimentation in type and construction of pallets, and usually far from optimum truck handling and loading methods.

Jan 1, 1961

By Michel Grenier, Gopal Kunchur, Stephen Hardcastle

This paper presents the findings of a dust study in a typical fluorspar processing plant. The primary purpose of this study was to identify employees and occupational groups exposed to high dust levels and determine compliance with personnel regulations for regular and extended work shifts. The range of airborne concentration of respirable silica and fluoride compounds in specific areas and on personnel was determined. State of the art dust monitoring equipment and tracer gas techniques were used to measure dust concentration, pinpoint dust sources and map major airflow trends in the mill. Results of the survey indicated silica dust concentrations in excess of permissible limits being produced mainly by crushers at the south end of the building. Tracer gas releases and gas chromatographic analysis further showed that prevailing south to north air currents tended to carry and spread dust produced by the crushing operations throughout the process plant. Airborne concentrations of fluoride compounds measured during the study were always well below the prescribed threshold limit value (TLV) for the contaminant. Recommendations, including a mechanical exhaust ventilation system on crushers and transfer points, scheduled preventive maintenance on existing bar sprays and wearing of personal protective equipment were made which significantly improved the work environment. Further testing conducted after Installation of the dust extraction system revealed significant improvements in most areas of the mill.

Jan 1, 1991

By Maurice Jackson et a1

Golder Moffitt and Associates (GMA)", were commissioned to reassess a large metallic low grade orebody. One of the aims of the study was to estimate recoverable reserves. Recoverable reserves are here defined as ore reserves for a specific mining block size. The mining block is that block on which the decision that the material is ore or waste is made. Recoverable reserves take into consideration mining methods. New methods for solving this type of problem were recently developed in Geostatistics and so for this reason GMA called for the technical assistance of the Centre de Geostatistique (C.G). The complete estimation was done using the geostatistical techniques and programs of the C.G together with some of the programs of GMA. As the mine was in production at the time the study commenced it was-possible to make frequent checks on the estimated values using blast-hole data. The ore reserves were also estimated using the more conventional interpolation method of inverse square of distance weighting.

Jan 1, 1979

By R. Larry Davis

Over the past decade there has been a continual decrease in domestic oil reserves accompanied by a sharp increase in the demand for energy. Even with increased imports of foreign oil, the energy demand has not been met. This has forced many users to turn to substitute fuels. Of the many substitute fuels available most users are turning to and creating an increased demand for low sulfur coal. Because of the increased demand for low sulfur coal as well as the inherent problems in producing eastern coal, many producers have turned their attention to the large deposits of low sulfur coal in the western United States. Western coal mining is, however, not without its problems such as high moisture content, high ash content, highly variable sulfur content, multiple seams, and/or pitching seams. It is to aid in the solution of these problems that this chapter is directed.

Jan 1, 1979

By Bruce D. Hulman, Robert .. F. Gorman

Introduction Groundwater resource evaluation has historically required extensive field investigative work, usually at great cost. More recently, the advent of the microcomputer has made difficult aquifer and groundwater evaluations comparatively simple and less expensive. A groundwater model is a numeric solution to a set of equations that calculates the water level in an aquifer or other types of water bearing strata. A computer will execute the solution of the set of equations rapidly and thereby permit evaluation of large amounts of hydrogeologic data rapidly. Computer modeling of groundwater resources is very often used to forecast the effects of multiple uses of a single groundwater resource. Modeling of heavily used aquifers has proven to be beneficial for averting problems arising from competitive use of a groundwater resource. This paper describes the work tasks performed in order to evaluate a large alluvial aquifer and thereby predict the hydrologic impact of additional groundwater withdrawal. Purpose and Scope Neyer, Tiseo & Hindo, Ltd. (NTH) was retained to evaluate the groundwater supply potential of the Missouri River alluvium underlying the Fairfax District in Kansas City, Kansas (Figure 1). The proposed groundwater supply is being considered for industrial use as non-contact process water and a heat exchange medium for plant climate control. The anticipated peak groundwater demand is estimated to exceed 30 million gallons per day (MGD) during the summer months, with an average daily demand of nearly 25 MGD. The proposed groundwater supply was to be developed from 15 large-diameter production wells located at positions that would minimize potential interference.

Jan 1, 1987

By T. T. Chen, J. L. Jambor, J. E. Dutrizac

A reconnaissance study of the neutralization potential of 30 diverse minerals, 28 of which are silicates and aluminosilicates, has shown that most of these minerals contribute minimally to the neutralization potential (NP) in standard static tests. Feldspars in particular give low NP values and would not be expected to attenuate the acidity to any significant extent in acid rock drainage settings. The BET-determined surface areas of the minerals vary considerably, and the large surface areas of some of the pulverized samples have clearly affected the NP values even though the standard static-test protocol was used for the preparation of the samples. The low NP values of most silicates and aluminosilicates are in general agreement with the laboratory-determined slow dissolution rates for these minerals. The results suggest that, in the prediction of whether rocks will be acid-producing, the most realistic measure is that of the carbonate content. In mine wastes from metalliferous ore deposits, the contribution to the NP by the non-carbonate gangue assemblage is unlikely to be more than a token amount until well after the establishment of an acid rock drainage situation.

Jan 1, 2000

By L. Tondo, W. Lim

The high pressure grinding rolls (HPGR) is a relatively new technology which offers the potential benefits in energy savings, circuit simplicity and improved product characteristics in minerals processing applications. Over 300 machines are now operating world-wide, but most of these are used for grinding cement clinker, and relatively few are used in conventional mineral processing. One of the rea- sons for its current limited use in the minerals processing industry is that design, scale-up and flowsheet assessment procedures are seen to be relatively immature and untested. This has reduced confidence in the potential application of the technology. To help rectify this situation an industry funded research project was undertaken, one of whose aims was to develop and prove a mathematical model of the HPGR and a scale-up procedure. Data were collected from tests using laboratory, pilot and in one case a full scale unit (2.2m diameter). A range of feed types were tested including quartz, limestone, kimberlite, bauxite, iron ore and gold ore. These data were then used to develop models of the size reduction performance, power draw, throughput and operating gap for a wide range of pressures, feed sizes, and roll speeds. This paper describes the models that have been initially developed and illustrates their accuracy using some of these data.

Jan 1, 1998

By Kenneth K. Humphreys

27.1-HISTORY, PROCESSING STATISTICS KENNETH K. HUMPHREYS 27.1.1-MINERAL PROCESSING HISTORY The processing of minerals predates recorded history. Many processing techniques have existed for thousands of years. For example, Georgius Agricola, in De Re Metallica (1556), described equipment and techniques, such as picking tables, smelting furnaces and cupolas of various types, sieves, launders. various types of crushers and grinders and other equipment, all still in use in one form or another. In translating Agricola's work into English, the late Herbert C. and Lou Hoover provided the following summary indicating the early history of particular mineral- processing operations :

Jan 1, 1973

By G. J. Melvin

Mines the world over tend to face a common range of problems. They begin life by trying to determine if there is sufficient product, usually under tons of earth, of sufficient quality to justify the operation. Once such a determination is made the mine must then be planned and brought into operation. Once operating most mines find that they are far away from suppliers, using very expensive equipment. Hence the three most common mining problems are, what does my ore body look like and how can it best be mined, how can I get sup- plies to my mine in the most cost effective way, and how do I control the vast dollars required to keep it all operating. Mincom started life by providing technical mining software to address the first of these problems and was very successful, particularly in the coal mining industry. However the company soon realized that if it was to become a significant provider of mining industry software it must also address the other major problem areas. Hence started what is now Mincom's largest business which is the provision of fully integrated mine management software with strong emphasis on materials and maintenance management to control costs. Mincom not only supplies the software but also provides a comprehensive implementation package using its own staff of experienced mining industry specialists. This papaer highlights some of Mincom's international implementation experiences.

Jan 1, 1989

By Yoginder P. Chugh

The term "fatigue" in mechanics, is used to refer to reduction in the strength of a material subjected to fluctuating or alternating stresses. Stresses that vary with time are called fluctuating stresses and if during fluctuation the stresses also change sign, they are called alternating stresses. In the field of rock mechanics, the term fatigue (static fatigue) has often been misused to refer to failure of geologic materials in time domain under constant load. To avoid confusion, we use the ten cyclic fatigue here to refer to failure of rock under alternating or fluctuating stresses. Fatigue in metals has been studied for over 100 years. Fatigue properties of geologic materials have, however, received little attention in the past. This is probably because until recently very little was known in regard to the behavior of geologic materials even under static loading. Secondly, suitable equipment for conducting cyclic fatigue experiments was not available until quite recently. A few cyclic fatigue studies have been undertaken on geologic materials to relate it to percussive or rotary drilling mechanisms (e. g. Grover et a11*; Burdine2). The results of these studies were inconclusive due to limited effort. Cyclic fatigue in concrete has been studied more extensively than geologic materials (e.g. Nordby3, Gray et al 4 and Bennett et a15) and mechanisms of fatigue in concrete are better understood than in geologic materials.

Jan 1, 1975

By S. K. Das

A detailed strata-mechanics investigation and examination was carried out in the E2 Panel (ML-II/7) of the XVI Bottom coal seam, which is located in the Moonidih Colliery of B.C.C.L., Jharia coalfield, India. Above this panel, the XVI Top coal seam was previously worked out by a longwall panel. Based on intensive field study and on experiments in a number of longwall panels located within various Indian coal mines, the actual behavior of the coal roof strata was evaluated and new strata-mechanics concepts around the longwall panels were developed. These concepts resulted in new methodologies concerning the behavior of roof rocks, caving characteristics, etc. within longwall panels and in the area of strata mechanics. Based on these new strata-mechanics concepts, a very simple, but realistic, model was developed to determine the optimum capacity of the powered supports. This model considered the combined loads resulting from the detachment of strata and composite layer blocks from the face and, also, loads due to the deflection of strata and composite layers situated above the detached roof rockmass. This formula, along with the other related formulas by the author, prompted the determination of the optimum capacity requirement for the powered supports to be used in the XVI Bottom coal seam, located under the worked out area. This new concept in strata mechanics and capacity requirements of the powered supports in a longwall face may be an aid to Mining Engineers.

Jan 1, 1997

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 Howard M. Cotton

Early in 1977, Amoco Production Company and Houston Chemicals, a subsidiary of Pittsburg Plate Glass (PPG) Industries, started producing iodine commercially in northwestern Oklahoma. This is significant because it is the first plant in over 40 years to be built in the United States with iodine as its sole commercial product. With the exception of a limited amount of iodine produced by Dow Chemical in Michigan, the United States is dependent upon imports from Chile and Japan for its iodine needs. The two million pounds of iodine produced annually from the Woodward plant will supply over one-third of the United States' requirements. Routine analysis of subsurface brines by the Formation Water Lab at the Amoco Production Company Research Center in Tulsa, Oklahoma, revealed unusually high concentrations of certain potentially economic minerals. Investigations determined that, of the minerals in question, iodine appeared to offer the best potential. The brines in question are located in the Morrow sands (basal Pennsylvanian) at a depth of 7,175 to 7.400 feet, in an area where Amoco has been active in a gas play for the past 20 years. The regional iodine concentration ranges from 10 to 700 ppm and averages around 300 ppm with the project area. The project is located 8 miles north and slightly east of the town of Woodward, where the well-developed, porous, and permeable sands of the Woodward trench contain large volumes of brine.

Jan 1, 1978

By Faruk Oksuz, Cary Hirner, Ray Brainard

"Key project participants, including owners, engineers, and contractors continually seek for sound and structured decision analysis on how to select the best contracting method for successful project delivery. In addition to being burdened with technical challenges, lack of resources, budget shortcomings, regulatory requirements, and bureaucratic and politically mandated obstacles, the project participants need a reliable decision analysis model on the best project delivery method. The pendulum of choice for contracting continually swings back and forth between traditional design-bid-build and alternative delivery options such as design-build, progressive design-build, construction manager at risk, and public-private-partnership. For large tunnel projects, the decision process is further complicated due to contract packaging options as well as risks in underground construction. Contracting strategies for large tunnels require thorough consideration of performance, risk, quality, operability, cost and schedule. This paper compiles an array of decision making criteria and tools for an unbiased and balanced evaluation and ranking system in the procurement of large tunneling projects. INTRODUCTION Successful project delivery hinges upon meeting the owners’ expectations and key performance indicators. Large tunneling programs benefit from a thorough understanding and successful implementation of project delivery options by key project participants including the owners, engineers and contractors. The key to success is a collaborative advancement of project as the key project participants knowledgably address the applicable management, performance, risk, quality, cost, operability and schedule considerations throughout a project realization cycle. PROJECT REALIZATION CYCLE All projects have customary planning, design, construction, commissioning and operation phases that may seem to be sequential but in reality that are well integrated and dependent on one another. A glitch in any phase of a project realization cycle could hinder a successful outcome and none of the project partners are immune to consequences whenever and wherever they may surface."

Jan 1, 2016