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By P. Chauvet

From a computational point of view calculating a variogram is a perfectly simple operation. For any particular study, we know which variable is to be studied. We also have a good idea of structural parameters which are likely to be important (the scale of the phenomenon, the probable direction of the anisotropy, etc.). Finally, we know the structure of the data file. So we can specify the parameters to be used to calculate the variogram (the distance classes, the angular classes, etc.). This allows us to decide which variogram program is most appropriate (1, 2 or 3 dimensional data, regularly or irregularly spaced, etc. ) . In general, the basic statistics (mean, variance, correlation? etc.) have been calculated beforehand, and so the distribution of the data is already known. Consequently, the choice of the parameter values fed into the variogram is by no means arbitrary. But it must nevertheless be made before the' variogram is calculated. If the resulting variogram is not satisfactory, the whole sequence of operations has to be repeated. Before going on to see how this can be avoided, it is worthwhile having a brief look at the common causes of "unsatisfactory" variograms.

Jan 1, 1982

By H. H. Murray

Industrial usage of clays for current and new applications will continue to grow into the next century. The rate of growth will be highest in the less developed areas of the world. Transportation costs are a significant part of the delivered price, so the location of reserves and processing facilities for kaolin, bentonite, and palygorskite (attapulgite) are reviewed relative to serving these emerging markets. New value added applications will increase in the more developed areas which will require high quality raw materials, more sophisticated processing, and rigorous quality control.

Jan 1, 1998

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 L. B. Rothfeld

Two new coal use technologies are on the verge of commercial acceptance by the utility industry: atmospheric fluidized bed combustion (AFBC) and gasification combined cycle (GCC). Generating plants under construction or in planning will replace older pulverized coal (PC) boilers or substitute for new PC boiler capacity. This paper reports recent developments in the commercialization of AFBC and GCC, emphasizing the potential impact on the coal mining industry. The influence of coal quality characteristics on fuel selection is explored by means of preliminary economic calculations for different coals and competing fuels.

Jan 1, 1987

By L. Alan Weakly

Coal mines and power plants utilize different methods to control dust for the safety of their workers and to protect their installations. The methods that they use are limited by the Environmental Protection Agency or the states in which they operate. Now there is a new technology for controlling dust at conveyor transfers! The Passive Enclosure Dust Control System utilizes several proven technologies to mitigate fugitive dust. This new system has been proven to be four times more effective than standard enclosures utilizing bag house collection and is considerably less expensive to install and operate.

Jan 1, 2000

By S. R. LaBrooy, J. Avraamides

Thermal reactivation of eluted carbon is an essential part of most carbon-in-pulp gold recovery plants. The effectiveness of the reactivation procedure depends on the nature and level of contaminants adsorbed on the carbon, the efficiency of the elution and the temperature, residence time and atmosphere within the kiln. The most commonly used kilns are evaluated in terms of their operating parameters and performance. Data obtained both in the laboratory and in the field emphasize the importance of carbon feed moisture content, kiln atmosphere and carbon conditioning on the activity of the kiln product.

Jan 1, 1998

By Jeffrey M. Listak, Gregory J. Chekan

The U.S. Bureau of Mines, in an effort to improve coal conservation and utilization is currently investigating longwall panel layouts to maximize coal recovery and minimize interactive problems in multiple-seam operations. When longwalling coalbeds in descending order, the transfer of stress from overlying gate roads is a major design constraint affecting pillar stability in the lower mine. The lower mine gate road pillars must be properly designed to withstand the additional load transfer if gate roads are superpositioned in successive seams. The Bureau's MULSIM/NL model was used to analyze load transfer mechanics for superpositioned gate road pillars. Analysis of Longwall Pillar Stability (ALPS), which is an empirically based design method for longwall gate road pillars, was used to calibrate model input parameters. The attributes of both the MULSIM/NL model and ALPS were combined to develop a modified method for estimating pillar stress for multiple-seam cases. The modified method uses a multiple-seam (MS) factor to estimate the stress on the lower mine gate road pillars when superpositioning is practiced. Numerical analysis shows that the MS factor is dependent upon the interburden thickness and pillar width and is presented in a series of graphs relating these two parameters. Several examples are included to illustrate the use of the MS factor for estimating lower mine pillar stress and resulting stability factors.

Jan 1, 1992

By L. Bomvisinho

As a result of today?s requirements for larger mills with higher power demand, and in order to cope with maximizing throughput, and optimize grinding efficiency, the minerals industry is increasingly relying on the robust Gearless Mill Drive (GMD) solution. This paper describes the new features introduced with the revolutionary ABB drive controller for Gearless Mills, and explains the benefits this can bring to the operation. Extensive surveys have been performed with GMD users to gather suggestions and understand the market wishes. As a result the new driver controller capabilities and functionalities focus on safety, high availability, operational flexibility and remote diagnostics.

Jan 1, 2010

By Andrew Torok

Activated bleaching clays, so called because of their ability to remove color bodies from bleach fats and oils, are produced from clays of bentonitic origin. Activation is achieved by subjecting these clays to physical or chemical alteration to increase selective sorption capacities (1) . The future of activated bleaching clays depends upon the ability of producers to recognize the new areas of applications which are arising, and their skill in developing sophisticated active clays to meet new and stringent requirements. The major portion of activated bentonites are produced for decolorization of oils. New techniques of activation will improve these clays for broader spectrum use. General properties expected to result from present activation methods are: 1. Modification of hydrophobic-hydrophilic properties and increased available surface area in non-aqueous systems, thereby improving sorption capacity and ability to remove color bodies from oils. The following additional properties will be expected from future activated clays: 2. High purity of the active clay with interfering impurities totally removed. 3. Increased selective sorption capacity in aqueous systems. 4. Selective chemical reactivity, such as oxidation or hydrolysis. This property is required for removing

Jan 1, 1971

By V. R. Voller

The WTBAL computer program for evaluating material balances for minerals processing flowsheets was developed at the MRC and has been in general use for a number of years. This paper reports on two enhancements to the basic MTBAL routine. The original program accounted for errors in the process measurements and used estimates of measurement variability to calculate stream weights. Unfortunately, the estimate of measurement variability was fixed over all streams. In the enhanced version of MATBAL, named IMTBL, the program equations and their solution procedure have been modified to allow the estimated variability in a process measurement to vary from stream to stream. The .second enhancement involves making MTBAL interactive. As such, the user now prescribes his information in an easy-to-use fashion in a conversational mode via a terminal. Finally, an assessment of the feasibility of implementing IMTBL on microcomputer systems will also be reported.

Jan 1, 1982

By D. Rumenjak

Fuzzy logic is a useful tool for Sustainable Development (SD) decision making because it can express uncertainty, both in the informational and in the decision-making environment. The general linguistic definition, acceptability for environment (air, water, nature, risk, etc.), as well other aspects of sustainable development (health, management issues, etc) is proved to be useful in approximate reasoning and decision-making. According to this definition, the various fuzzy functions of environmental acceptability can be constructed. This construction is based on the concept of special kinds of fuzzy functions generally defined as Linguistic Variables (LV), which are suitable for mapping to fuzzy sets. Various SD indicators could be used as domains of such functions, expressed either in their physical values (e.g. production, emissions, risk of accidents) or in Measure of Preferences (MP). The most important MP are mentioned below: Stated Preferences Techniques (SPT) of economic evaluation of environment, economic instruments of environmental protection mostly based on Revealed Preference Techniques (RPT), preferences scales (ordinal, cardinal) according to various methods of their construction, etc. Also, the possibility theory (analogous to probability) could be exploited in such construction. It could be used together with environmental engineering modelling formulas for the purpose of determining fuzzy functions. The appropriate forms of linguistic variables, considering limit cases for this purpose, are also discussed.

Jan 1, 2007

By Robert D. Brown, Charles A. Sorrell

The decade of the 1980's saw "advanced materials" become a key factor among the industrialized nations, with the United States, Japan, and the European Economic Community being the major competitors. All three have identified communications technology, advanced materials, and biotechnology as the keys to future industrial leadership and the closing decade of the 20th Century is expected to be an era of rapid development and restructuring. The progress of EC'92, the effort to develop uniform standards and remove trade barriers in Europe; the determination of Japan to commercialize advanced structural ceramics, alloys, composites, and superconductors; and the emergence of less developed countries as major supplies of commodity materials pose enormous challenges to the position of the United States as an industrial and financial leader. A consensus is developing that the industries that are first to commercialize the large array of new structural materials and electronic, optical, and magnetic materials and devices will be those who determine the structure of national and world economics. Many technical, economic, legal, political, social, and cultural factors are important determinants in the race to commercialize new materials. Millions of words have been written about these factors and their interdependence; yet the sheer complexity of the problems, the rate at which changes are taking place, and the economic risks involved are so great that government policy makers and industrial decision makers find adequate understanding to be very difficult. Of the many factors involved in advanced materials, the Bureau of Mines has the statutory responsibility to provide information on where materials can be found and how they are mined, extracted, purified, combined, and recycled. It is obvious that minerals availability is essential to implementation of any new technology just as there can be no commodity metals industry if the ores are not available. Because "minerals availability" for commercialization of advanced materials and devices is more complex than for commodity materials and a new mix of materials and processes is emerging, the Information and Analysis Directorate of the Bureau of Mines is redirecting resources to provide reliable information for policy and decision making. The Office of Advanced Materials Coordination (OAMC) was established as a staff operation in July 1987 to assist the efforts of the divisions and branches. The key issues and problems were defined and the role of the Bureau was outlined (Sorrell, 1987, 1988). In February 1990, the functions of OAMC were transferred to the new Branch of Advanced Materials, a line organization parallel with the Branches of Ferrous, Nonferrous, and Industrial Minerals, and was given the responsibility for developing new methods to acquire, analyze, and disseminate information about new materials. The purpose of this paper is to provide definitions, a summary of major issues and problems, an overview of minerals and processing availability problems, and a perspective of the ways in which the mining and materials industries can help to ensure domestic availability of raw and processed materials.

Jan 1, 1990

By Young C. Kim

In the past, underground coal mine planning has traditionally focused on the mine design n aspects concerning safety and efficiency in the quest to produce low cost coal. Very little attention has been given to coal quality control aspects of mine planning at most of the underground coal mines within the U.S. With the enactment of the clean air act of 1970, the generally high sulfur content of coal has become a major concern for the coal-fired power plants in the east. Similarly, the ash and the BTU contents of coal are of equal importance from boiler efficiency standpoint. Thus, the time has come when the coal mine planning must incorporate the coal quality control aspects as well as the traditional safety and efficiency aspects.

Jan 1, 1983

By Silver Miller, William A. Vogely, J. C. Emerick

After location and verification of exploitable mineral resources, mineral development re- quires capital goods, labor, and energy to extract the deposit. In addition, a growing social awareness of the need for a healthy environment re- quires inclusion of environmental burdens to the total costs incurred. This is because mineral development is detrimental to the environment in a number of ways. All mining .operations involve the separation of valuable minerals from the surrounding waste rock, which in turn re- quires permanent disposal of unwanted or un- used materials. Mine overburden, wastes, and tailings are often transferred to peripheral areas where they remain as unsightly features in the natural landscape. Some mine spoils contain harmful or contaminating substances as heavy metal salts or acid forming materials which subsequently are released to the environment. Many types of mining operations handle significant quantities of water during extraction or beneficiation processes. When discharged, the quality of such water often is unsuitable for residential, agricultural, or recreational use. Since mining activity disturbs the natural vegetation in the project area, water may be allowed to transport soil materials into streams, causing erosion and siltation. In particular, surface mining operations disturb the top layers of soils, resulting in losses of productivity for long periods of time. Excavation, transportation, and further processing of large volumes of both ores and waste materials generate substantial quantities of particulate and gaseous emissions, some of which contain metal dusts or compounds of sulfur. Such fugitive and point source emissions can be transported beyond the confines of mineral operations to cause annoyance and damage at more distant locations. Environmental degredation or pollution can be viewed as the alteration of the environment by man through the introduction of materials which represent potential or real hazards to hu- man health, disruption to living resources and ecological systems, impairment to structures or amenity, or interference with socially desired uses of the environment. The significance of environmental degradation is reflected in its effects on a range of receptors, including humans as well as the resources and ecological systems upon which we depend. Pollution also is judged in the social context of damage to environmental structures and amenities. The demand for restoration and maintenance of environmental quality presents the mineral industry with a challenge to successfully man- age discharges and returns to the environment in order to avoid undesirable and harmful consequences. AIR QUALITY Impacts of Mining and Beneficiation Operations Air quality generally is degraded by mining operations through the addition of dust or total suspended particulates (TSP), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), and hydrocarbons (HC) to the atmos-

Jan 1, 1985

By John E. Edkins

Metal sulfides, chiefly pyrite and mFnor sphalerlte zssociated with che Herrin (No. 6) coal member of the Pennsylvania Carbondale Formation, have been concentrated in a coal refuse deposit in southern Illinois. Oxidation of pyrite has produced highly acid waters with high concentrations of iron, zinc (up to 200 parts per million) and toxic trace elements that have leached downward to a water system perched on glacial drift. Chemical, petrographic, low-temperature ashing and x-ray diffraction were performed on cores. The data show that economic recovery of zinc and other trace metals is unlikely at this site. Energy (coal) recovery at the Superior Washer site is possible if resultant environmental problems are considered in the planning.

Jan 1, 1981

By John N. Murphy, Edward F. Fries

The availability of fast, low-cost computer hardware and advanced software is opening new opportunities for minerals extraction and processing. Programmable Logic Controllers (PLC's) are currently used extensively in the minerals industries; this paper looks beyond PLC's and that vintage of “computer control”--it looks toward what the authors see as new in the next five years. Topics covered include expert systems, neural networks, intelligent signal processing, and hierarchical controllers as applied to mining and mineral processing operations.

Jan 1, 1993

By Mritunjoy Sengupta

The Green River formations in the Western U.S.A. contains vast amounts of petroleum reserves in oil shale deposits. Exploitation of this petroleum reserve calls for large scale mining of the oil shale. Applicable mining methods include conventional underground mining using roan and pillar, sub-level caving and block caving; underground insitu retorting of oil shale and open pit mining. Roam and pillar mining offers one of the most economic methods of underground mining of oil shale. A 2.4 x l09 litre per year (50,000 barrels per day) of crude oil production would require a daily oil shale production of 100,000 tomes per day from underground operations. For this large production, a highly mechanized room and pillar mining muld utilize large capacity diesel equipment such as 85 tonne trucks and 8m front end loaders. The total air requirements of an oil shale mining operations can. be as high as 28443/s. Ventilation planning for such a large scale underground mining operation presents a formidable task. The major objectives of providing ventilation air to underground workings are to dilute airborne .dust and diesel fumes to harmless levels, and to insure that the mine environment is compatible with the health and safety of mine personnel. Regulation of air velocities and air temperatures is a major factor in mine environmental control. Colorado State law requires that a minimum of 0.047m3/s of fresh air be supplied for each kW of diesel power operating underground. Additionally, 0.047m3/s of fresh air must be supplied for each underground employee, and a minimum air velocity of 0.15m/s must be maintained in all working places. It is desirable to exceed this minimum velocity in order to prevent stratification of ventilation air. Moreover, Colorado law also stipulates the maximum allowable concentration of noxious gases mine air, below: ? C02 - 0.5% by volume, 5,000 ppm. ? CO - 0.005% by volume, 50 ppm. ? Oxides of Nitrogen - 0.0025% by volume, 25ppm. ? Nitrogen Dioxide 0.005% by volume, 5 ppm. This paper examines ventilation requirements for the underground mine, with respect to air quality requirements and distribution of air in mine workings in light of the above regulations. Analyses were made for sane typical mining plans to determine airflow resistance or pressure drops and fan horsepower requirements. In addition, the possible occurrence of high concentrations of toxic gases, was examined. Expected temperature levels in mine workings were approximated.

Jan 1, 1980

By Alfred Petrick, Roger Dewey

INTRODUCTION Estimation of capital and operating costs for mines and mills has long been a necessary ingredient of feasibility studies, and though many practitioners have successfully used "rules of thumb" and factor estimating methods for many years, a great deal of work is usually required to prepare an initial estimate and/or to update or revise such an estimate. Development of comprehensive mining and milling cost models during the 1970's by the U.S. Bureau of Mines and by Canadian workers (O'Hara and Mullar) provided the basis for feasibility-level cost estimates, but the numerous equations and the apparent rigor and complexity involved in preparing a project estimate using these models has discouraged many, if not most, potential users. Their acceptance was also hindered by a broad misunderstanding by many engineers in the minerals industries who had little exposure to such procedures, and by a possibly inadequate level of explanation or documentation of the parametric approach to cost estimating. The preliminary nature of most databases, geologic/engineering/ and market, available to the engineer or analyst during the early stages of a mineral project is a universal problem. Basing corporate mega-investment decisions or even individual equipment selection decisions on the usual "SWAG’s has always been a risky practice, but in the current business environment, the "guesstimates" are almost 'verboten', and are certainly becoming antiquated with the advent of both the described models, the ubiquitous microcomputer, and the nearly-ubiquitous hybrid species known as the "computerized engineer". Engineers have almost always sought techniques of cost estimation that can be applied and justified when geologic and engineering information for a mining project is preliminary and incomplete. The answer, in some cases, is the "parametric" approach. Equations, based on actual, past experience are developed to relate capital and operating costs to major physical variables such as the rate of mining or milling, with modifiers for such details as mining method, process characteristics, methods of construction, or types of equipment . Cost Engineering Standards Five major types of fixed capital cost estimates have been defined by the American Association of Cost Engineers : 1. Order-of-Magnitude estimate based on previous cost data and minimal knowledge. usually a "ratio estimate" with no better than +/- 30% accuracy. 2. Factored or ratio estimate based on major equipment costs with probable accuracy in the 25 to 30% range. 3. Budget authorization or Preliminary estimate, based on sufficient project data to

Jan 1, 1987

By Sukumar Bandopadhyay

In recent years, research in the field of artificial intelligence (AI) has had many important successes. Among the most significant of these has been the development of powerful new computer software known as the "expert systems". Expert system programs designed to provide expert-level consultative advice in mineral exploration (Duda et al, 1981), scientific (Feigenbaum, Buchanan and Lederburg, 1971) and medical (Shortliffe, 1976) problem solving are generally acknowledged to be among the forerunners of this research. As the decision makers virtually in all fields face a more complex and involved world within which to operate, the need for some decision support is also becoming urgent. Thus applications of expert systems continue to spread out reaching problems that, because of their dimensions or particular aspects, set more demand on the decision methodologies. To meet these new requirements, many activities which were performed in the past by the domain expert or engineer must become automated. Furthermore, previous research (Dawes and Corrigan, 1974; Dawes, 1979) has shown that automating an expert's decision rules often provide better decision than the expert does. For large systems it would be very useful (or even necessary) to have formal tools, allowing one for example, to automatically discover inconsistencies, contradictions or redundancies, or to identify the possibilities of wrong lines of reasoning in the decision process.

Jan 1, 1990

By Kirk P. Kinart

The mid to late 1980s saw a modern day global gold rush that largely focused on the mature mining countries of the United States, Canada and Australia. This gold rush led to a large number of new discoveries in these countries and phenomenal growth rates in annual gold production. For a variety of reasons, however, gold exploration and development activity appears to have peaked in these countries. The drive for mineral investment is, instead, growing in lesser explored countries (LEC). LECs, particularly those of Latin America, are currently enjoying greatly increased attention from North American mining companies. They are becoming major consumers of mineral investment capital and are important markets for exploration and mining skills. Through sole ownership, joint ventures and subsidiary companies, Battle Mountain Gold now operates or controls gold mines in the United States, Chile, Bolivia and Australia. And it has been or is an active participant in gold exploration or development projects in seven other countries, six of which classify as LECs. In selecting new country entries and opportunities for mineral investment, there are several factors to be considered and parties to be satisfied - shareholders, corporate management, financial institutions and host country governments. This article, though, focuses on some of the more practical concerns of the exploration unit as a whole and the exploration geologist in particular. The exploration unit's "new country" concerns primarily relate to exploration potential, ownership security, quality and availability of data and the ability to operate efficiently. The following material reviews each of these concerns and how they impact the new country entry decision, exploration strategy, chances of success and human experience.

Jan 1, 1993