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By R. V. Ramani

"In a 1985 seminar, we were told that over-optimism abounds in Artificial Intelligence (AI), that AI is neither a science nor a technology yet, and that we will be both exhilarated and disappointed with AI. In fact, even today, there is no single accepted definition of AI; however, certain features have been identified by AI researchers as essential to consider an entity (e.g. machine or program) to be intelligent. According .to Shank (1987), these features include communication (to be able to communicate with), internal knowledge (knowledge about itself), world knowledge (awareness and knowledge about the world outside), intentionality (knowing what one wants and a plan to seek it, ie. goal seeking behavior), and creativity (being adaptable to changing conditions). None of these figures would individually define intelligence; however, each would be a part of intelligence in its own way.The prospects for the development of entities with AI have never been as good as they are now. The combination of advancements in computer hardware and .software along with new insights into the ways in· which we store knowledge and use it for problem solving has enhanced the potential for the creation ~f intelligent entities. After some unbounded optimism of a major breakthrough in the fifties and frustrating disappointments in the two following decades, it appears now that AI has emerged from research labs to industrial practice. This is confirmed by the growing number of repeat applications of AI in business and industry to the extent that AI can now be considered a technology.AI applications are categorized into several distinct areas such as Natural Language Processing, Speech Recognition and Synthesis, Expert Systems, Robotics, Machine Vision, etc. Of these practical realizations, Expert Systems (ES) has the greatest potential for meeting the decision-making needs of the manager in the ever-growing complex scoio-technical systems. Prof. Feigenbaum, an expert and leader on expert systems, has defined Expert System as"" ... an intelligent computer program that uses knowledge and inference procedures to solve problems that are difficult enough to require significant human expertise for their solution. Knowledge necessary to perform at such a level, plus the inference procedures used, can be thought of as a model of the expertise of the best practitioners of the field."""

Jan 1, 1989

By Eugene H. Skinner

The U.S. Bureau of Mines conducted experiments on the use of lightweight concrete in the density range of 100 Ib/ft3 for liners in underground mines. Three test sections were completed: a monolithic, portal-type structure with integral walls and arch constructed aboveground; an underground test section constructed in a mine drift using plywood forms; and a second section constructed in a drift using an air-supported formwork. The lightweight concrete in the two underground test sections was placed using piston pumps and a slickline. Fiber reinforcement was added to the concrete in the mine sections without any apparent problems with either pumping or placement of the concrete. In another experiment, the Bureau and Hecla Mining Co., Mullan, rD, used lightweight concrete in the density range of 25 Iblfe to replace timber blocking in a raise preparation structure. Other experiments are described in which low-density, lightweight concrete blocks were produced for mine ventilation doors, stoppings, and barricades. Other mine uses reviewed include pillars and collapsing beams. An advantage of low-density concrete is that it will display up to 50% deformation at a constant yield stress. These hlllovative concepts in deformable concrete lining systems will aid mine operators by decreasing capital and maintenance costs, increasing the available space in underground haulageways, and providing productivity gains and improved resource recovery in the soft, caving, squeezing, or bursting grollnu conditions often found in deep mines.

Jan 1, 1989

By L. Adler

Existing classifications of mining and construction equipment have had major deficiencies. They often lack organization, balance, and have remained obscure. Particularly when proceeding to great.er resolution these deficiencies have proven crippling. By adopting "Classes", "Groups" f "Types" and "Kinds" at successive degrees of refinement, a "Taxonomy" is developed based on clear visual differentiation or on a "Morphology??. This symbiotic application, adopted from the Biological Sciences, yields clear, simple and unambiguous results. Supporting this effort are guidelines for easily and credibly sketching equipment which are also distinctive. Numerous illustrative examples are provided. Communications are improved and the engineer obtains a confident feel for the equipment at hand.

Jan 1, 1989

By T. S. Krishnan

Among the established permanent magnets, SmCo5 magnet occupies the foremost position as it offers a unique combination of high energy product, coercivity and curie temperature. The SmCo5 magnets are thus extensively used for high field applications. These are also best suited for use in environments where high demagnetising field and high temperature are operative. Also, for applications where high performance and miniaturisation are the over-riding considerations, the choice again falls on SmCo 5 magnets. The main deterrent to the widespread use of SmCo5 magnet is its high cost. Both samarium and cobalt metals are high priced, and the magnets prepared from their directly melted alloy are thus naturally very expensive. An alternate process involving calcium reduction of their oxide intermediates has, therefore, been studied and the alloy prepared by this process has been evaluated and found satisfactory for magnet production. The process essentially involves compaction of the charge mix containing samarium oxide, cobalt oxide (or metal) and calcium metal and' reduction of the charge compact at 1000-1300°C in hydrogen atmosphere, followed by water and acid leaching, drying and classification. The calcium reduction process offers three distinct advantages over the conventional melting processes: (i) The oxide intermediates are relatively cheaper and do not pose any handling problems. (ii) The operation temperatures are comparatively lower and hence precise composition control is possible as samarium losses due to volatilisation

Jan 1, 1989

By I. Tinto

"IntroductionEnvironmental pollution problems, caused by gases or effluents, by high noise levels or from air borne dust, are placing increasing demands of the operators, from statutory authorities, and from the general public, to adopt more stringent dust control measures. This requires that a successful plant dust control program be an integral part of any plant operation. While a successful environmental program is a key factor in maintaining productivity and good labour relations, anticipation of future environmental regulations during the plant design phase can avoid the high cost of plant upgrading, or dealing with pulmonary conditions in the work force in subsequent years.Particulate removal, conventionally called dust collection, involves the removal of coarse- and fine-particulates from the airstream. Although generally limited to that required for contro!Hng plant generated air emissions, particulate control equipment also has a wide application for air cleaning and filtration inside the plant, as well as for recovery of usable products.In the late 1950s and early 1960s the public became more concerned with the problems of air pollution. This increasing concern was stirred by an awareness of the extremes to which water pollution had progressed in many of the rivers and lakes, by increasing perception of air pollution as detected by visible smog and harsh chemical odors, by the alarming rate of increase of smog plagued cities and communities, and by specific incidents where ill health could be traced to specific episodes of air pollution. Particle size is perhaps the most important single factor affecting particulate control. Large particles (over 5 microns) constitute the major mass fraction of most sources of emission and economical control equipment dqes exist for their efficient control. However, while these larger particles frequently represent the source of soiling and unsightly smoke plumes, they are not a major health problem as they tend to settle relatively quickly, are more easily scrubbed from the atmosphere by rain, and are not able to penetrate the respiratory system. By far the most important form of particulate air pollution is the fine particulate, (below 3 microns) which is harmful to the pulmonary system. The adverse effects caused by this particulate matter on human health are for the most part related to injury to the surfaces of the respiratory system. Particulate material in the respiratory tract may produce injury itself, or it may act in conjunction with gases, altering their sites or their modes of action. A combination of particulates and gases may produce an effect that is greater than the sum of the effects caused by either individually (i.e. synergistic effect)."

Jan 1, 1989

By Jennifer S. Riefenberg

The U.S. Bureau of Mines conducts basic and applied research related to predicting, eliminating, and/or controlling rock bursts in underground hard-rock mines and coal bumps in underground coal mines. An important element in this research is the development of a reliable and efficient microseismic source location technique. This report presents the results of a Bureau study to develop and evaluate a new algorithm to locate microseismic events based on the Simplex method, a powerful linear programming technique. The technique was tested on both field data and simulated data. Microseismic event source locations obtained with this new Simplex-based algorithm were shown to have less error than those locations obtained using a least squares method. It was concluded that the Simplex approach to source location of microseismic events can be used effectively in microseismic monitoring.

Jan 1, 1989

By C. S. Ek

Tests have been performed to recover silver and lead from residues produced after a super-hot leaching in a zinc hydrometallurgical plant operating with jarosite precipitation. When this residue is leached in ammoniaammonium sulfate or in diethylenetriamine solutions, lead dissolution is not complete and its recovery from the aqueous solutions is either difficult, due to the operating conditions, either expensive due to the amount of added reagents. In both cases, silver is partly dissolved, partly left in a new residue still containing lead and baryum sulfates. The best treatment seems to include a selective flotation producing first a silver concentrate assaying about I % Ag, then a 50 % lead concentrate collecting the baryum salts, and a final quartz-gypsum tailing. Metal recoveries can reach 50 % and 80 %, respectively.

Jan 1, 1989

By Concentrator Staff

"IntroductionA brief literature search will reveal that the information available concerning rod mills and ball mills is quite extensive. This type of equipment is used to treat every element from antimony to zinc. The size and capacity of individual mills, the number of units employed, and the configuration of the equipment within a concentrator add another dimension to the possible scope of this discussion. It would be impossible to treat this volume of material with any degree of thoroughness.It is the intention in this paper to describe the simplest and generally the most typical circuit wherein a single rod mill and ball mill operate in parallel. Some of the subject matter will not be entirely applicable to every installation. However the principles should be generally relevant to most applications.Typical Circuit DescriptionFigure 1 illustrates the arrangement of the equipment associated with a rod-ball mill circuit.Ore is extracted from a fine ore storage bin (1) the capacity of which is large enough to allow .continuous mill operation independently of the mine and crushing plant production schedules. A number of feeders (2) may be employed to control the flow of ore to one or more feeder conveyor belts (3). In larger tonnage operations several such conveyors are employed at least one of which will be equipped with a variable speed control to allow adjusting of the amount of feed reporting to the rod mill. A rod mill feed conveyor (4) accepts all of the ore from these feeder belts for ultimate transfer to the rod mill. This conveyor is normally equipped with a weightometer (5) to monitor the flow rate of ore to the rod mill and ultimately to allow control of this flow. Typically these conveyor belts would be equipped with feed deficiency switches which would give a remote alarm of the fact that no ore is present on the conveyor. The conveyor belts are protected by underspeed monitors which will provide a remote alarm and automatic shutdown of the conveyor in the C'.'~nt that belt slippage occurs. Finally the belts are protected by monitors which will alarm and shut down a belt if it is not running straight in the idlers."

Jan 1, 1989

By Alan P. Prosser

The heap leaching of gold ores by cyanide solution was simulated by computer program. The program uses only basic m1neralogical and chemical data; no process testwork data, such as column leach results, are required. The simulation can be used to forecast the consequences of various changes before and during the testwork, design and operation stages of a particular ore-process system. Also, data about the state of different parts of the heap at various times help create an understanding of what is happening. The effects of mineralogical and process variables on the overall performance of the ?heap leaching process are illustrated. Comparisons are made to column leach tests and production data. The potential of the simulation strategy is discussed for making better use of operating experience and for suggesting specific research objectives. It has become clear that more attention should be paid to other metals that dissolve in the solution.

Jan 1, 1989

By Thomas J. Ferree

"IntroductionThe objective of this chapter is to provide important criteria relating to the operation and maintenance of spiral concentrators and Reichert cones, so that optimum performance can be achieved and maintained in a mill circuit. Little space will be devoted to the theory of the forces of separation or the technical details of the devices, as that in(ormation is available from other sources. The discussions in this chapter will be presented in a manner that should be interesting and useful to anyone who may be exposed to these methods of gravity separation. It is most important for the reader to understand that each application of the equipment should be considered on its own merit, as no two suites of minerals respond exactly alike in mineral processing circuits. The information herein should be useful as a guide toward increasing the metallurgical efficiency of the processes, irrespective of the type of minerals being concentrated.It is highly recommended that certain tools be made available to the personnel responsible for metallurgical performance of the spirals and cones; these include a set of standard type laboratory screens, a medium quality petrographic microscope, and a vanning plaque or gold pan. These devices, when used in conjunction with a basic understanding of the mill circuit, provide immediate knowledge on the characteristics of any sample in the mill circuit. The information gained by visual evaluation of sized fractions of products can solve many of the basic problems of mineral beneficiation, and at the same time increase the interest of the non-technical personnel associated with the plant operation. There are many problems associated with obtaining satisfactory performance from a mill operation. Many of the problems have to be solved using a technical approach. Some of the problems, however, can be solved with practical knowledge and common sense. It is hoped this chapter can provide a guide to both techniques."

Jan 1, 1989

By George A. Savanick

The U.S. Bureau of Mines has patented and transferred to industry an abrasive-enhanced water-jet rock drill. This drill incorporates three novel components: a collimator, jet deflectors for cutting clearance, and an unpressurized swivel, which rotates at 1,000 rpm while passing 20 gpm of an abrasive slurry flowing at 1,000 ft/s. Drilling occurs through the action of a 10,000-psi, 2O-gpm water jet into which is entrained 72 lb/min of abrasives. The pumps, hoses, and fittings are those commonly used in the water-jet-cleaning industry. Only inexpensive, common sandblasting abrasives are used. This drill can cut through hard rocks with moderate-pressure jets; e.g., rocks with a compressive strength of 73,000 psi can be drilled with a 1O,OOO-psi abrasive jet. In addition to drilling holes, the drill can cut deep, narrow kerfs; collar a hole at any angle; drill through rubble; and chamber holes. The development of the abrasive jet drill is a significant advance in the state of the art of hard-rock drilling. The Government of the United States has licensed the abrasive jet drill patent to Weatherford Water Jetting Systems.

Jan 1, 1989

The geographical region of South East Asia is variously defined, but generally agreed to include the Asean group - Philippines, Malaysia, Thailand, Singapore and Indonesia. Other regional countries, such as Vietnam, Laos, Burma, Kampuchea etc. are of course geographically part of the region, however in economic terms, they play a minor role. It is the Asean group that dominates present economic activity and provides the overwhelming opportunity for commercial development. My experience in South East Asia has been gleaned over 15 years of regular travel in the region. More recently, we have established company offices in Malaysia, Singapore and Indonesia to extend and deepen contacts with major customers. This progressive development is an integral part of a planned growth pattern and will be discussed in more detail shortly. South East Asia is a rapidly developing economic growth centre, a fact which is clearly recognised and accepted by most commentators. An important question is then to be asked: Why has the region been relatively neglected by Australian, U.S. and European industrial supply companies? I will attempt to address this question in the context of industrial minerals and propose some ideas as to how effective sales programs could be developed. Firstly, let's consider the market potential provided by countries within the region. It is reasonable to suggest that industrial growth in S.E. Asia over the past 20 years has been generally steady and in some cases, explosive. Until recently, this growth has predominantly been driven by development of internal (regional) demand. Population growth and rising living standards have ensured that basic industries have enjoyed a solid uptrend in sales and production. The industries which most benefitted from regional economic development over this period were, interestingly, those which we understand to be major users of industrial minerals - glass, ceramics, paper, surface coatings, cement, refractories, rubber and plastics. Each of these industrial sectors has been influenced by different growth stimulii over a 20 year period. Nevertheless, they also enjoy a common feature which ensured an above average performance. All sectors are fundamental to an environment enjoying rising living standards and rapid growth in general prosperity. More recently, internal growth factors have been overtaken by a recognition that manufactured products from the region are competitive in export markets. This comparatively recent development provides the most interesting possibilities for higher value industrial mineral raw materials. Let me explain: For 20 years, industrial growth in South Asia has essentially been focused on satisfying domestic demand. Finished quality of manufactured items was orientated to a developing market more interested in cost than aesthetics or long life. This was reflected in raw material specifications, which often did not exist and at the best were undemanding.

Jan 1, 1989

By C. W. Whitten

Solis from an abandoned Pb battery processing facility were characterized prior to the selection of the extraction technique. Reflected light microscopy and electron beam methods were used to locate Pb-bearing phases and to quantify the compositions of the phases. It was found that the soils are composed primarily of quartz and feldspars with minor amounts of iron and titanium oxides. Lead is primarily present as an oxide or sulfate that is associated with the silicate minerals. Specific phases identified were PbO; Pb02; cerrusite, PbCO3; angleslte, PbSO4; galena, PbS; and magnetoplumbite, 2PbO3Fe2O3; or plumboferrite PbO2Fe2O3?

Jan 1, 1989

By D. W. Zandee

"IntroductionHaving mined an economic mineral bearing rock which is of insufficient grade to warrant direct smelting, upgrading or beneficiation is required to make it an economically viable ore. The first step in effecting the concentration process is comminution or sequential breaking of the rock to allow liberation and subsequent recovery of the desired mineral particles. Desirably the ore could be broken down to the point where the valuable mineral is completely liberated to maximize the chance of recovering as much of it and in as pure a form as possible. The number of energy intensive stages of breakage required to attain this goal depends on many physical characteristics of the ore such as hardness, friability, toughness, grain size, existing fracture planes and particle shapes.Commonly the distinct stages are primary, secondary and often tertiary crushing and finally grinding. To increase the efficiency of each stage of size reduction, pre-treatment sizing is common.Crusher feed is commonly scalped of large pieces or screened for reduction crushers and classified for secondary grindingcircuits.Although crushing and screening is employed for many different products, this chapter reviews current practice in larger tonnage metalliferous ore treatment plants.Current practice is to use large gyratory or jaw crushers for primary crushing and some sort of gyrating or cone crushers for additional stages of reduction. For autogenous or semiautogenous grinding circuits only the primary crushing stage is necessary, the balance of the work being performed in the grinding stage. For conventional grinding circuits using ball mills or combinations of rod and ball mills, secondary, tertiary and even quaternary crushing stages are normally required.Older type crushers such as stamp mills, double rolls, sledging mills and hammermills are no longer common but are used for small tonnage special processes.Important to efficient crushing are a variety of sizing devices such as grizzlies and vibrating screens. Products at different stages must be stored to give surge capacity and allow controlled feeding rates through mechanical and gravity feeders. These storage piles, bins and feeders as well as crushers and screens are commonly integrated into a total facility by means of conveyor systems. Most often these are endless rubber belts driven by simple or multiple drive mechanisms usually consisting of electric motors and speed reducers."

Jan 1, 1989

By Fridrik J. Kristjansson, Stephen R. Hicock

"Three varieties of till are recognized in the Beardmore-Geraldton area: local lodgement till, nonlocal carbonate till, and local supraglacial till. The local lodgement till unit is examined in detail for the first time in this paper. It is the best potential overburden exploration medium for gold and other metals because its particles were locally-derived and deposited subglacially, probably within a few kilometres downglacier (southwestward) from their sources, and have not been diluted by distantly-derived glacialdebris. Both local tills are richer in gold and other metals, relative to nonlocal carbonate till. Local lodgement till rests on bedrock and was encountered frequently at or near the surface in thin drift/bedrock terrain (a widespread terrain type within the west half of the study area), and commonly at the base of boreholes in thick till terrain.INTRODUCTIONDrift prospecting in areas of glaciated terrain has been well documented (in a variety of journal publications and symposium volumes; e.g . Strobel and Faure 1987; MacDonald and Mills 1988) and has proven valuable especially where overburden thicknesses hinder traditional exploration techniques. Drift prospecting techniques may well prove valuable in the Beardmore Geraldton area. This applies especially to the Wildgoose Lake Turkey Lake area where a thick and laterally extensive sheet of nonlocal carbonate till has impeded conventional mineral exploration programs (Fig. I; note the lack of gold occurrences around Wildgoose Lake).Till in .particular has been cited as the best prospecting medium among the various types of glacial sediment (e.g. Shilts 1984). Three end member till varieties are recognized in the study area: (I) local lodgement till which rests directly on bedrock; (2) non local carbonate till; and (3) local supraglacial till which occurs predominatly within, or just downglacier of, upland areas where it commonly mantles the other till varieties. Previous authors have documented how the non local carbonate till hinders gold exploration (Geddes and Kristjansson 1986; Karrow and Geddes 1987; Kristjansson 1986; Hicock 1986, 1987a, b, 1988; Kristjansson and Thorieifson 1987; Thorleifson and Kristjansson 1987, 1988a, b) and why the local supraglacial till may be a good unit for prospecting (Hicock 1986). One detailed surficial geology map sheet of the area has been published (Kristjansson et al., 1988) and others are in preparation. Closs and Sado (1981) reported on the geochemistry of soils and glacial sediments in the west half of the study area. This paper documents the local lodgement till unit and demonstrates why it is the best overburden unit to use for drift prospecting."

Jan 1, 1989

By D. Milne, P. Germain, G. Sauriol

"The practical determination of optimum stope geometry has, until recently, been an art relying primarily on experience at a given operation. Due to the complex and variable nature of rock masses in situ, stopes are often designed either very conservatively, resulting in excess development, or non-conservative resulting in excessive dilution and, in some cases, in loss of ore reserves.The Geomechanics group of the Mining Technology Division, Centre de Recherche Noranda, uses a combination numerical modelling and empirical design techniques to optimize allowable stope geometries. The above methodology allows the optim ization of stope geometry for varying rockmass classifications within an operation or between different operations. Such techniques require the development of a thorough geotechnical database at each operation and are best used when calibrated to the specific operation through back analysis.This paper discusses the above optimization techniques in light of specific examples from the Noranda Group. The design methods, limitations and results are discussed.INTRODUCTIONMine design has traditionally referred to production planning, general facility layout, (i.e. ore passes, crusher stations, main haulage drifts, etc.) and ventilation design. The dimensioning and sequencing of the stopes and pillars, however, has been almost solely based on trial and error and precedent practice.More recently, numerical stress analysis has received much more attention as part of the design process. It is common now at many operations to look at the effect of proposed stope layouts and sequences on stress redistribution through the surrounding mine workings. Through calibration of actual stope and pillar behaviour in situ, one can then relate the model predictions to support requirements, safety problems, etc."

Jan 1, 1989

By Thomas M. Barczak

This U.S. Bureau of Mines report is intended to assist coal mine operators in the selection of longwall supports by providing advanced guidelines for performance testing and standardized test documentation to facilitate support comparisons. These advanced guidelines culminate in a series of proposed tests to evaluate (1) support resistance characteristics, (2) stiffness characteristics, (3) leg mechanics, (4) stability, (5) load transfer mechanics, and (6) structural integrity. The Bureau has conducted extensive studies on shield mechanics to identify boundary conditions that induce loading in support components, which is often not included in current testing techniques. This report discusses influential parameters that affect support behavior and provides insight into how components are loaded and what conditions produce the most severe loading. Testing philosophies and techniques in both active and static frames are discussed. Proper methods for determining support resistance are described and instrumentation requirements for advanced performance testing are provided.

Jan 1, 1989

By Staff

This U.S. Bureau of Mines publication presents the results of investigations into the fire and explosion hazards of oil shale rocks and dust. Three areas have been examined: the explosibility and ignitability of oil shale dust clouds, the fire hazards of oil shale dust layers on hot surfaces, and the ignitability and extinguishment of oil shale rubble piles.

Jan 1, 1989

The process of pile driving disturbs the soil around the pile. The nature and magnitude of disturbance depends upon 1) the pile size, and 2) the nature of soil. Therefore, the prediction of a single pile behavior based on soil properties of undisturbed soil samples may not match its performance. Under lateral loads, the pile may loose contact with the soil near the ground surface especially in clays. The soil pile interactions are influenced the most by pile behavior in this zone. This situation further affects the tally of prediction and performance. Piles are used in groups. The zones of overlapping stress from one pile to the other both around the pile and below their tip particularly in soft soils, contribute to group effects. Empirical solutions have been developed for prediction of the pile group behavior. The group action is more involved under vibrations. Several cases of single piles and pile groups under static and dynamic loads from published records have been analysed. It has been shown that single pile test is the best source of information on the soil-pile-soil interaction effects.

Jan 1, 1989

By R. J. Barnes

Consider a typical blast at a surface gold mine in North America. For example, the low-grade area of Bench 4000 at AMAX Gold's Sleeper Mine (Winnemucca, Nevada). Bench 4000 is 20 feet high (=6m) , and blast holes are drilled and sampled on a 14 foot by 14 foot square grid (a4m x 4m). A representative blast includes between 50 and 150 holes, encompassing 15,000 to 45,000 tons of material (w14,000 to 41,000 metric tons).

Jan 1, 1989