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By Ian Longson, Darron W. Dixon

This paper describes the results of an investigation into the application of a statistical method for the prediction of general air-body methane concentration in longwall coal districts. An important and necessary part of the research was the acquisition of representative monitored mine environmental and coal production data. The monitored data was used to build time series models of general air body methane concentration, air velocity, barometric pressure, coal production and methane drainage variables of differing timescales according to the Box-Jenkins method of time series analysis. The univariate models were used to identify causal relationships between methane concentration and its explanatory variables. Coal production was found to be the dominant variable in the determination of the quantity of methane emitted and where appropriate, multivariate time series models were built in which expressions for methane concentration in terms of coal production were obtained. Finally, forecasts of methane concentration values were generated from the multivariate models to determine their forecasting capabilities.

Jan 1, 1993

By Thomas W. Mitcham

A program of geological research in support of mineral exploration efforts is outlined. Specific goals are stated, approaches to accomplish their attainment are described, and the type of useful results to be expected are outlined. Because mineral exploration or prospecting has intensely practical goals, research in support of it must be applied research, applied to the problem of maintaining or increasing the discovery rate of the exploration effort. To attain research goals, attention to personnel selection, group structure, and program are critically important, and in about that order. A large percentage of the professional personnel should have had experience in mining geology or mineral exploration, and they all should be prospector-oriented. Structuring in the group should be at a minimum, with wide allowance for the kind of independent research which is essential to the nurturing of on-target creativity. The program should be field-oriented, and it should include a wide representation of those subdisciplines of geology which are applicable to mineral exploration. The types of results to be anticipated include improved or new conceptual models for various types of orebodies and their settings from which new ore guides can be derived, new exploration techniques, and the development of a knowledge bank for various aspects of the exploration effort.

Jan 1, 1968

Mining was the first economic activity carried out in Cuba, by the colonial conquerous, i.e. gold extraction from rivers and use of asphalt to calk their ships; however, due to different historic reasons only a limited development took place in this field during the colonial domination. During the republican period beginning early in this century, other interests lead to a larger scale exploitation of some known deposits. From the beginning of the century up to the triumph of the Revolution in 1959, not less than the following figures were extracted of some Cuban minerals: Refractory Chromium 3,300,000t Manganese 7,650,000 t Copper 9,000,000 t Iron 22,000,000 t Nickel 150,000 t (Ni oxide and sulphide These productions were practically directed to cover the demands of the U.S., industry and some-times these Cuban ores were almost the sole suppliers of the market.

Jan 1, 1978

By Robert Harris, David Duncan

The Samira Hill gold mine represents the first commercial gold project for the landlocked country of Niger in West Africa. It began production in October 2004 as the result of over 10 years of exploration and development work. There were several administrative, social and technical challenges that had to be overcome to realize the successful development of the project. The Samira mine is located on the geological structure known as the ‘Samira Horizon’ which is developing as a promising district for additional discoveries and other mine developments.

Jan 1, 2005

By D. Campos, J. M. Macedo, S. Chadwick

The incorporation of low cost technology transfer to increase the ability of locals to acquire and maintain long term employment are key ingredients for sustainable industrial development. Alcoa’s Alumar plant on the island of Sao Luis is the largest and most modern refinery/smelter complexes in northern Brazil. The plant has one of the most advanced Environmental, Health, and Safety management process in the aluminum industry. Technical assistance, training and financial support were made available to Alumar to address social sustainability issues. Through several programs led by employees on a voluntary basis and applying intensive and extensive training programs, Alumar has enabled local people to develop skills on agriculture and land management, wastes minimization, small business development and administration, all based on sustainable development and social responsibility concepts.

Jan 1, 2004

By D. W. Frommer

In continuing its long range studies of methods of treating low-grade iron ores, the Bureau of Mines has developed a new selective flocculation, desliming, and flotation procedure that enables effective beneficiation of the finely disseminated ferruginous jaspers of the Marquette range, Mich. The process, developed on a bench scale and later confirmed in the 800-lb/hr pilot plant, comprises dispersion, selective flocculation, desliming to reject fine silica and clay, and flotation of silica from the remainder of minus 400-mesh pulps. Pilot plant flotation of two Marquette range ores, using the selective flocculation procedure on feeds containing 36 percent Fe, yielded iron recoveries of about 84 percent in concentrates containing 65 to 66 percent Fe and 4 to 5 percent silica. These results were metallurgically superior to those obtained when selective flocculation was not used. Also operating characteristics were better, and reagent costs were lower.

Jan 1, 1964

By Grant P. Cordon

Our subject, "Safety, Legal, and Contracting," is a range of topics which covers a broad spectrum, but is obviously Intended to focus our attention upon certain particular aspects of tunnel problems. These are all fascinating and complex subjects, and others are much more qualified to discuss to discuss the fine points involved. Put after some 45 years' involvement as an inspector, engineer, contracting officer, and especially for the last 22 years as a contractor's estimator and manager, I have developed some strong and definite convictions to share with you. I hope it will serve to get you started thinking. My first tunnel experience was in a soft ground tunnel which was dug by hand, literally. The crown or arch back was taken out, a pebble at a time, by bare hand. The face was constantly breast-boarded, and the mucking was all done by hand shovel. My first rock tunnel was drilled by hand held drifters from the muck pile. Since then, most tunneling techniques have improved greatly. The jumbos, booms, muckers, and moles have taken over many of the back-breaking chores, and reduced the manpower requirements.

Jan 1, 1974

By S. E. Valji

Clay slurries are normally dewatered using flocculents like sulfuric acid or aluminum sulfate. This type of flocculation is based on the electrolytic mechanism. For certain clay dewatering applications, this method of flocculation is unsatisfactory. Flocculation, based on the bridging mechanism, using organic polymers has been utilized to overcome such problem situations. This method of flocculation offers solutions not possible by previous methods. Normally these flocculents are used to assist dewatering. In this case, not only is dewatering promoted, but also further processing is assisted by a change in the dilatant character of the filter cake that is formed. Discharge of filter cake is easier, extrusion of filter cake on to conveyor dryer is possible or improved, and heat transfer and drying rates of the extruded filter cake are substantially higher. Both natural and synthetic organic polymers have been utilized for this purpose. Selection, application techniques, and economics are described.

Jan 1, 1965

By M. Karmis

Surface subsidence has been recognized as an inevitable consequence of underground coal mining for several centuries. The damage resulting from this phenomenon has been witnessed in rural as well as in urban areas and ranges from simple land settlement to severe structural damage to buildings. Subsidence prevention is not feasible, at least under the existing technological and economic constraints of underground coal mining. Using a rational method of subsidence prediction, it has been demonstrated in many coalfields that subsidence control can be successfully practiced in order to reduce and accommodate subsidence within environmentally acceptable levels. This paper presents the development and testing of a subsidence model, based on the zone area method. This technique is a refined development of the influence functions and it is capable of investigating a mining plan of any shape, thus facilitating both longwall and room-and-pillar mining systems. More specifically, this study can be divided into two major efforts: (a) The development of the zone area model. This formulation was designed to accommodate the analysis of an optimum number of zones, over the area of interest, both accurately and efficiently. (b) The testing of the computer techniques with appropriate field measurements. In order to accomplish this, published as well as unpublished information was collected and analyzed according to a regionalized scheme. This procedure minimized differences in subsidence characteristics between the various coalfields and allowed a regional validation of the predictive capabilities of the model.

Jan 1, 1982

By H. T. Mulryan

Talc is used as an essential ingredient in a variety of plastics applications ranging from polyester body patch compounds through polypropylene automotive, appliance and household furniture components to high performance parts made from liquid crystal engineering resins. This paper focuses on polyolefin applications, the three-tier market for talc in polypropylene, the effects of various tales in typical compounds and trends in each market segment. Emphasis is given to emerging markets, examples of which are polypropylene compounds that mimic higher cost resins, and polyethylene films. Customer requirements, for tales for these purposes are discussed.

Jan 1, 1993

By H. T. Mulryan

Talc is used as an essential ingredient in a variety of plastics applications ranging from polyester body patch compounds through polypropylene automotive, appliance and household furniture components to high performance parts made from liquid crystal engineering resins. This paper focuses on polyolefin applications, the three-tier market for talc in polypropylene, the effects of various tales in typical compounds and trends in each market segment. Emphasis is given to emerging markets, examples of which are polypropylene compounds that mimic higher cost resins, and polyethylene films. Customer requirements for tales for these purposes are discussed.

Jan 1, 1994

By J. Rao Mokka

Extensive exploration has resulted in delineation of a massive sulfide district on the north flank of the east-central Alaska range. The district covers approximately 400 square miles and contains numerous stratiform; transported and some replacement type sulfide deposits ranging in size from less than 1 million tons to 20 million tons. Five types of ores were sampled for the study. Mineralogical analysis revealed that the minerals are too fine grained for conventional grinding and beneficiation. Hydrometallurgical studies were con-ducted using ferric chloride as a lixiviant. Ore microscopic studies as well as electron microprobe analyses of minerals in the raw samples and leach residues explained the low recoveries for certain elements as well as sources of impurities that need to be eliminated from the process streams.

Jan 1, 1991

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 A. G. Taylor

High value materials, such as gold, platinum and other precious metals are subject to loss through unauthorized removal from mines, smelters, refiners, and other places where such materials are processed. A study published in 20011 determined that between 1994 and 1998 an average of 603 kilograms of gold per year was stolen from South African miners and subsequently recovered. This does not include the gold that was stolen but not recovered. At 2011 prices, 603 kilograms of gold would be worth approximately $33 million. Mine security personnel believe that the unrecovered stolen gold far exceeds what is recovered2. Traditionally, metal detectors have been used to screen personnel leaving secure areas to discourage such unauthorized removal. However, with the current near-record prices of gold, platinum, and other precious metals, it has become worthwhile for people exiting a facility to walk out with quantities of product that are too small for ordinary metal detectors to register, resulting in substantial financial losses.

Jan 1, 2012

By E. A. Devuyst, G. Robbins

A unique process for removing cyanide and base metal complexes from industrial waste streams was patented by G.J. Borberly et al. (1984). The process uses SO2 (liquid or gas, or solutions of sulfite salts, or from burning elemental sulfur), plus air that is dispersed in the effluent using a well agitated vessel. Acid produced in the oxidation reactions is neutralized with lime at a controlled pH generally in the range 7 to 10. The reaction requires the presence of soluble copper as a catalyst which can be supplemented by copper sulfate if necessary. The process can be applied to the detoxification of gold and silver mining waste streams, such as carbon-in-pulp (CIP) tailing pulps, barren solution bleeds, pond waters and heap leach rinse solutions and also to plating shops wastewaters. The SO.jAir process has substantial advantages over two of the main alternative methods of cyanide destruction, namely alkaline chlorination and hydrogen peroxide. Alkaline chlorination is highly penalized in terms of reagent consumption. Chlorine is a strong oxidant reacting with species other than cyanide present in the effluent such as thiocyanate and sulfides. Furthermore alkaline chlorination is an incomplete detoxification process. Iron cyanide is not removed and the potential for harmful by-products species exist. Consequently final effluents may be subject to additional treatment in order to comply with regulatory demands.

Jan 1, 1991

By A. Pomianowski

A spectrophotometric study of xanthate solutions alone and their mixtures with equimolar amounts of alkyl trimethyl ammonium bromide (CnTAB) has established the additivity of ultraviolet spectra (190 - 400 my) for potassium ethyl xanthate (KEtX) and C12TAB. No obvious effect of C12TAB addition on the decomposition rate of KEtX was observed. The kinetics of collector abstraction by copper, nickel and sphalerite powders were studied in 10-5 - 10-3M solutions of KEtX alone and in equimolar mixtures of KEtX and C12TAB. Presence of C12TAB caused a 2 - 3 fold increase in the amounts of xanthate (equivalent to many monolayers) abstracted by copper and, nickel powders but had no effect on the abstraction of xanthate by unactivated sphalerite. The adsorption of C12TAB itself from the mixed solutions was very low, at most ore monolayer only, and was not influenced by the nature of the solid powder used. The results are interpreted in terms of molecular associations and synergistic action of xanthates and quaternary amines.

Jan 1, 1963

By Bhawani Singh, A. K. Dube, B. Singh

At least three hydroelectric tunnels constructed during the last decade through the lower Himalayan region in India have met with serious problems of supporting in squeezing ground conditions. Steel ribs under went intolerable deformations requiring rectification to provide space for concrete lining which delayed the projects inordinately. In an attempt to choose a rational method of predicting rock load, the authors have compared rock loads estimated from various classification systems and elasto-plastic theory with observed values. The deficiencies of the classification systems have been highlighted to show that the combination of elastoplastic theory and tunnel instrumentation programme provides better guidelines for the design of tunnel supports in squeezing ground conditions.

Jan 1, 1981

By M. K. Mohanty

One of the main objectives of this study was to evaluate a fine-coal cleaning circuit using an enhanced gravity separator specifically for a high sulfur coal application. The evaluation not only included testing of individual unit operations used for fine-coal classification, cleaning and dewatering, but also included testing of the complete circuit simultaneously. At a scale of nearly 2 t/h, two alternative circuits were evaluated to clean a minus 0.6-mm coal stream utilizing a 150-mm-diameter classifying cyclone, a linear screen having a projected surface area of 0.5 m2, an enhanced gravity separator having a bowl diameter of 250 mm and a screen-bowl centrifuge having a bowl diameter of 500 mm. The cleaning and dewatering components of both circuits were the same; however, one circuit used a classifying cyclone whereas the other used a linear screen as the classification device. An industrial size coal spiral was used to clean the 2- x 0.6-mm coal size fraction for each circuit to estimate the performance of a complete fine-coal circuit cleaning a minus 2-mm particle size coal stream. The ?linear screen + enhanced gravity separator + screen-bowl circuit? provided superior sulfur and ash-cleaning performance to the alternative circuit that used a classifying cyclone in place of the linear screen. Based on these test data, it was estimated that the use of the recommended circuit to treat 50 t/h of minus 2-mm size coal having feed ash and sulfur contents of 33.9% and 3.28%, respectively, may produce nearly 28.3 t/h of clean coal with product ash and sulfur contents of 9.15% and 1.61%, respectively.

Jan 1, 2008

By R. S. Mateer

Linear programming on desktop computers is commonly used to optimize coal blending proportions. The objective function is usually the cost of the blend. The constraints consist of materials and heat balances as expressed as linear functions of the blend. This is illustrated in Example 1. Inclusion of a sulfur compliance constraint in more complex because the maximum permitted sulfur percentage is not a pre-specified constant. Rather, it is a function of the calorific power of the blend itself. The current limit of 1.2 pounds of sulfur dioxide per million Btu may be expressed as: [Sulfur Max%= 0.6 . Hl10,OOO with H in Btu/lb.] A proper constraint equation may be formed by defining for each coal a function that is the difference between the actual sulfur percentage and the maximum sulfur percentage. This may be regarded us an excess sulfur percentage. For Coal A of Example 1. this would be: [ Sulfur Excess%=0.5-0.6 13,000/10,000=-0.28] This value would be used as the coefficient of the weight proportions of this coal in the blend. The complete constraint equation would then be the sum of such terms for each coal set less than or equal to zero. This is illustrated in Example II. [ ]

Jan 1, 1995

By Y. Luo

Based on the concept of slope stability analysis, a formula for determining an important parameter required in the mathematical model for the prediction of mining subsidence in hilly terrain has been proposed. The slope geometry and soil physical and mechanical properties of the surface natural slope can all be considered in the formula. Incorporation of this new formula into an existing mathematical model provides an integrated approach in studying ground movement in hilly regions.

Jan 1, 1998