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By James Terry Duce

In order to facilitate interpretation of the data in this chapter, we print the following excerpts from circulars to authors, compiled by Mr. Frank A. Herald when he was Vice Chairman for Production of the Petroleurn Division: Generally in Table 1 the unit for presentation of data is a field. For our purposes a field is defined as the whole of a surface area wherein productive, locations are continuous. Such unit commonly includes and surrounds nonproductive areas. Such unit commonly includes a great variety of geologic conditions-—several units of continuous productive reservoirs of distinctly different structure and of distinctly different stratigraphy. Therefore it is hoped that our authors will subdivide "field" so as to enable students to make analyses that may have scientific and/or commercial value. As to each space in the tabulation, it is either (1) not applicable, (2) the proper entry is not determinable, (3) the proper entry is determinable, but not determinable from data available to the author, (4) the proper entry is determinable by the author. In spaces not applicable, the author will please draw horizontal lines; in spaces where the proper entries are not determinable, the author will please insert 2; in spaces where the proper entries are determinable but not determinable from data available to the author, the author will please insert y; in spaces where the proper entries are deter-minable by the author he will, of course, make such entries. Generally, y implies a hope that in some future year a definite figure will be available. Inability to determine precisely the correct entry for a particular space should not lead the author to insert merely y. Contributions of great value may be made by the author in many cases where entries are not subject to precise determination. In such cases the author should use his good judgment and make the best entry possible under the circumstances. For many spaces, the correct entries represent the opinion of the author (for example, "Area Proved") and in such cases the entries need not be hedged to such extent as in cases where the quantities are definite yet can be ascertained only approximately by the author. In cases under definite headings but where figures are only approximate, the author may use 2. For example, if the total production of a field is known to be between 1,800,000 and 1,850,000, the author may report 1,8xx,xxx; or if the production is between 1,850,000 and 1,900,000, the author may report 1,9xx,xxx. Where a numeral is immediately to the left of x or y, such numeral represents the nearest known number in that position. As to quantity of gas produced from many fields the question will arise as to whether the figures should include merely the gas marketed or should include also estimates of gas used in operations and gas wasted. Although rough approximations may be involved, our figures should represent as nearly as possible the total quantity of gas removed from the reservoir.

Jan 1, 1936

Solar Salt, Lunar Ambitions I Bauerti The title of this paper is `Solar Salt, Lunar Ambitions'. It is largely the result of a lack of imagination and a tight deadline. I was seeking a catchy title to convey the image of being 'here' and wanting to get `there', with `there' being a long way away and our being held 'here' by powerful gravitational forces. I tried `Solar Salt, Lunar Landings', but that implied we had already reached `there' when, on reflection, we had not. A colleague suggested 'Solar Salt, Luna Park' which is a fun park in Sydney and, I must admit, there was appeal in the image of having embarked on a wild roller coaster ride with stomach-wrenching twists and turns and the only reward being a pair of sweaty palms, and a feeling of nausea. That's sometimes how it feels when you launch into change. In the end I settled for the more sedate `Lunar Ambitions'. It contained that suggestion of hope and continual striving which are central to the idea of best practice. I will discuss our experiences in this area shortly, but I would firstly like to provide some background to our business. The salt industry is steeped in history and tradition. As one learned commentator observed, common salt is 'a substance seemingly too ordinary to think about, yet it is the oldest of man's raw materials and the basis of some of his newest inventions' (Multhauf, 1978). From ancient times, salt was recognised as a key necessity of life and it has played a role in the rise and fall of governments throughout history. The Romans recognised its importance when they gave their soldiers money regularly to purchase salt, hence our modern word 'salary'. Today, while culinary use remains important, the main consumer of salt is the chemical industry (Figure 1).

Jan 1, 1995

By Henry N. Doyle

Basic procedures in the mining industry have changed only slightly over the centuries since metals and fossil fuels became an essential part of man's economic and cultural life. Mining techniques of the 20th century bear a close resemblance to those of the ancients: exploration, ore breakage and removal, hoisting, and processing. The great advances, however, have been in equipment and machinery of greater size and speed which allow greater efficiency in each of these operations, with a corresponding reduction in manpower requirements. Yesteryear production was measured in pounds per man-day; today a giant and complex, but highly efficient, continuous mining machine can remove as much as eight tons of material a minute from the coal face. If our energy and metal demands of the future are to be met, and at this time it can be assumed that coal will continue to supply a significant part of the energy demand, other dramatic and spectacular technologic advances must be accomplished. Along with mechanization, however, public policy will require the industry to place greater emphasis on health and safety protection, as has been well demonstrated by recent actions of Congress. Together, fossil fuels and metals formed the basis for the industrial revolution-coal to develop power and metals to transform power into useful energy. Strangely enough, however, the mining industry the world over has lagged behind the continuous social changes brought on by the industrial revolution, such as preventive health and industrial hygiene services, and other programs directed to the well-being of the worker. In some countries this resistance, to change may have led in part to the nationalization of the coal industry. Whether this disinclination to social change in the industry of the United States reflects managerial attitudes, inept labor leadership, government neglect, or economic relationship would be the subject of an interesting study. Doubtless the mores of miners and their resistance to change, as well as their geographic isolation from other industrial groups, may have had a strong influence on these factors. In every major coal mining country the accident rate in the coal industry is substantially higher than other industrial groups, and the cost of pneumoconiosis compensation in some countries is greater than the combined costs for all other occupational diseases from all other industries. The high social cost of occupational accidents and diseases may have been a factor in the closing of the industry in at least two countries. Despite diminishing manpower needs, the industry is faced with critical manpower shortages. Miners once reared their sons to be miners; now it appears that the opposite is true. This factor alone, however, does not explain an acute labor shortage in the industry. Traditionally, the industry drew much of

Jan 1, 1976

By M. Jackman

"Froth stability is critically important for an effective separation of fine and ultrafine particles using column flotation. While a desirable froth stability is required to facilitate the drainage of entrained gangue particles for secondary cleaning, excessively stable froths could create problems in separation efficiency and down-stream processing. In this work, we demonstrate that a stable foam was produced using a poly (N-isopropylacrylamide) (PNIPAM) solution at the temperatures below the critical solution temperature. In contrast, very little foam was produced at the temperature above the critical solution temperature (~32 oC) of PNIPAM. We can also tune the foam stability by changing the temperature of wash water. When warm water of temperature of 50 oC was applied, the foam collapsed and diminished. This is probably attributed to the switching of PNIPAM molecules from coiled to a globule conformation as the temperature is increased. Our results indicate that the foamability and foam stability can be tuned by tempartureresponsive PNIPAM. This is the first time that thermo-responsive PNIPAM has been shown to have potential as a modifier of froth stability in column flotation.INTRODUCTIONIn mineral processing, column flotation has become a more prevalent process in the separation of fine mineral particles (typically < 100µm). Traditional flotation cells are sometimes less efficient in selective separation of ultra-fine particles (Kohmuench et al., 2009). The efficiency of flotation columns is dependent on the froth stability at the top of the cell to drain the unwanted gangue particles entrained in the froth. The greater froth height in flotation columns, compared to mechanical flotation cells, gives a longer froth residence time, allowing more of the drainage process to take place before the froth reports to the launderer. Secondary cleaning, by applying a wash water shower to the froth, enhances drainage of gangue particles entrained in the froth, and improves the recovery of the targeted minerals (Finch et al., 2007).While a stable froth is desirable to facilitate drainage of entrained gangue particles, greater amounts of fine particles have been found to contribute to excessively stable froths which could create problems for down-stream processes (Bethell et al., 2012). Operators have tried spraying additional wash water on the froth, and reducing frother dosage to destabilize the froth and to prevent backup at the launderer. The former is sometimes inefficient, and the latter results in unacceptable recovery loss. Currently, the best practice is often the installation of larger froth launderers, adding expensive defoaming agents, and/or using deaeration tanks (Bethell & Luttrell, 2005)."

Jan 1, 2016

By Sebastian Ernst Volkmann, Felix Lehnen

"INTRODUCTIONWhile today’s mine planning of land-based ore deposits follows methods, which are well established, mining standards for the deep-sea have not established. Having gained a basic understanding of geological settings, there is still a lack of tools and methods to assess and plan future mining projects in the deep-sea. In the framework of the “Blue Mining” research project (2014-2018) technologies and methods for the exploration and exploitation of deep-sea minerals are developed that will bring deep-sea mining a step closer. The “Blue Mining” project receives funding from the European Commission (EC; Framework Programme 7; GA No. 604500) and addresses all aspects of the value chain in the field of deep-sea mining. The project philosophy is that deep-sea mining is planned and executed in the most responsible manner: Ensuring societal benefits and profitability at acceptable resource utilization and lowest possible environmental footprint (Volkmann 2014).Inspired by the high-tech farming industry, a concept to mine seafloor manganese nodules (SMnN) was developed. Mining is considered to be similar to the potato harvest on land (Figure 1), which involves mining a field partitioned into long, narrow strips (Volkmann and Lehnen 2017). The proposed mining system composes of one mining support vessel (MSV), one or two self-propelled, crawler-type seafloor mining tools SMT(s) and different types of underwater vehicles. The MSV follows the mining route of the SMT(s), picking up the about potato-sized nodules from the seafloor. The ore is pre-processed in situ and is lifted on board of the MSV, where the ore is dewatered and loaded onto bulk carriers for transport to the purchaser. Processing and refining of ore is not subject of “Blue Mining” research."

Jan 1, 2017

By Guangwei Wang, Changle Zheng, Yifan Chai, Jian Guo, Weiwei Geng, Jianliang Zhang

In this paper, characteristic and kinetics of CO2 reaction with four different kinds of coke such as top-loading coke, dry quenching tamping coke, wet quenching tamping coke and semi-coke were investigated based on isothermal method. Electric resistance reduction furnace was used to heat the sample. Volume Model (VM) and Shrinking Core Model (SCM) were used to calculate the kinetic parameters and to contrast with the experimental results. The results showed that the Volumetric Model (VM) was much suitable for the reaction of top-loading coke, dry quenching tamping coke and wet quenching tamping coke, while Shrinking Core Model (SCM) was much suitable for semi-coke.

Jan 1, 2015

By Pan Zhao, Yan-Nan Wang, Fei-Long Liao, Can Cai, Kai-Song Wu

"What are the basic physical parameters and main geometric parameters that are capable of representing the microscopic characteristics of rock? How can these parameters be used to accurately describe the macroscopic mechanical behavior of rock? With such questions in view, and based on the microcosmic structure analysis of rock slices, this paper presents a rock skeleton-pore structure model, holding that rock's mechanical behavior depends on the properties of rock skeleton materials and the form, size and distribution pattern of pores. According to rock stress and deformation behaviors, and in line with the skeleton-pore structure model, an essential mechanics theory for rock is advanced. The assumption that the skeleton materials are incompressible in volume and an introduction of logarithmic strain, generate the relation between porosity and apparent strain. Then, the notion that positive damage and negative damage are represented in terms of porosity is put forward; threshold value of porosity is derived by the damage threshold value of apparent volume strain; a general damage variable of rock is obtained; eventually, with the skeleton-pore model as the groundwork, a global damage constitutive equation is developed, which, with definite physical significance and material parameters to be easily determined, is convenient to apply. It has been proved that the results calculated with this new equation are well in agreement with experimental results.INTRODUCTIONRock is a form of material that contains pores, cracks and skeletons. Skeletons are composed of particles and cements. Pores or cracks within rock actually undermine the assumption of material continuum in solid mechanics. Hence, grave errors — or even false results — are inevitable if some solid mechanics theory is quoted in the discussion of rock mechanics. Many researchers in the field of rock mechanics have attempted various remedies, but the outcome is far from satisfactory — a mechanics theory for rock, in its true sense, has not been established."

Jan 1, 2015

By Jessica Elzea, Haydn Murray

The term bentonite was first proposed in 1898 by Knight, a year after he had named this clay taylorite, because taylorite had been previously used for another mineral. The name taylorite was after the Taylor ranch, the site of the first mine, near Rock River, WY, and the name bentonite is from the Benton Shale in which the clay was thought at that time to occur. The Benton Shale was, in turn, named after Fort Benton, MT, located more than 640 km miles north of Rock River. Early in the 20th century, several geologists recognized that bentonite, mainly in beds in Cretaceous and Tertiary rocks, originated from transported volcanic materials. This recognition led to definitions based on origin, the one most widely quoted and generally accepted by geologists is the following definition by Ross and Shannon (1926): "Bentonite is a rock composed essentially of a crystalline clay-like mineral formed by devitrification and the accompanying chemical alteration of a glassy igneous material, usually a tuff or volcanic ash; and it often contains variable proportions of accessory crystal grains that were originally phenocrysts in the volcanic glass. These are feldspar (commonly orthoclase and oligoclase), biotite, quartz, pyroxenes, zircon, and various other minerals typical of volcanic rocks. The characteristic clay-like mineral has a micaceous habit and facile cleavage, high birefringence and a texture inherited from volcanic tuff or ash, and it is usually the mineral montmorillonite, but less often beidellite." The difficulty in applying the foregoing definition to bentonite as an industrial mineral commodity is that it is based on origin and is restricted to an ash, tuff, or volcanic glass parent material. Therefore, deposits consisting of the clay minerals required by this definition, but having uncertain origin or parent materials, cannot properly be called bentonite. Furthermore, many deposits in the western United States and in other countries that have formed from rocks other than the types required by the definition are being mined and sold as bentonite. Perhaps the best definition of bentonite as an industrial mineral is one given by R.E. Grim in a plenary lecture at the International Clay Conference (AIPEA) at Madrid, Spain, June 27, 1972. According to this redefinition, which will be used in this chapter, bentonite is a clay consisting essentially of smectite minerals (montmorillonite group of some usages), regardless of origin or occurrence. This definition solves the problem of the difference between the geologic and industrial usages of the term and overcomes the difficulty in assigning a name to smectite clay that formed from igneous rock other than ash, tuff, or glass, or those of sedimentary or uncertain origin. However, bentonite, when used with this meaning is still a rock term (consisting of more than one mineral), and it will not be possible to distinguish it from fuller&apos;s earth in many instances. One way of classifying bentonite is based on its swelling capacities when wet or added to water. Bentonite having sodium (Na+) as either the dominant or as an abundant exchangeable ion typically has very high swelling capacities and forms gel-like masses when added to water. Bentonite in which exchangeable calcium (Ca++) is more abundant than other ions has much lower swelling capacities than sodium varieties. Some calcium types swell little more than common clay, and most crumble into granular masses in water. Intermediate calcium-sodium bentonites, the so called mixed types, tend to swell moderately and to form gels of lesser volumes than equal masses of the sodium type bentonite. Because of the general relationship of swelling and exchangeable ion characteristics bentonite is commonly divided into the high swelling or sodium, low swelling or calcium, and moderate swelling or intermediate types. The term sub-bentonite (Davis et a]., 1940) is used inconsistently in industry for the low or moderate swelling varieties. The authors believe the use of this term should be discouraged because of its implication of low quality or low value and the lack of a mineralogical or use basis for it. In the United States bentonite is also classified by geographic location and the uses for which it is sold. Inasmuch as most of the low swelling calcium type occurs in states bordering the Gulf of Mexico, this variety is commonly called Southern bentonite. The largest high swelling sodium bentonite deposits and the major producing districts are in Wyoming and adjacent states. Therefore, this bentonite is commonly called the Wyoming or Western type. Such terms as drilling mud bentonite, foundry bond bentonite, and taconite bond bentonite relating directly to use are applied in marketing. Other terms including high and low yield bentonite, high and low gel bentonite, and high and low strength bentonite are also used to distinguish different grades. The varied classifications notwithstanding, bentonite occurs in so many different varieties that some cannot logically be classified according to any of the foregoing groupings. One of these types is hectorite, which is a high swelling lithium-bearing variety of smectite occurring mainly in California and adjacent states. It is, therefore, not a Wyoming type, and it occurs even farther west than the so called western bentonites. Others are bentonites having magnesium (Mg++) or hydrogen (H+) as the most abundant or dominant exchangeable ion. These types are neither sodium nor calcium varieties, and apparently some are low swelling, whereas others have rather high swelling capacities. Still another type of bentonite, the so-called potassium type, K-bentonite, or metabentonite, occurs in Ordovician and other Pa-

Jan 1, 1994

By K. C. Ko, D. A. Pifer

The theory of probability with respect to the failure of structures is discussed. It is shown that the probability of safety, probability of failure, and factor of safety are directly related to each other and that as standard deviation approaches zero, the probability curves approach a unit step function which can be interpreted as the conventional factor of safety. The factor of safety is numerically the ratio of the load to the strength of the material at a particular point or plane in an engineering structure. Mathematically, it can be illustrated as a unit step function undefined at the point where the factor of safety is one (Fig. 1). The uncertainty of variation of soil and rock strengths require factors of safety much higher than those used in other engineering structures. The factors of safety used are generally determined from past experiences with similar structures. However, the factors thus determined do not have any theoretical meaning or do not indicate any relationship to actual safety.&apos; It seems, therefore, logical to develop a system with a sound theoretical basis to obtain a more suitable factor of safety for structures. An application of elementary theory of probability indicates that it is possible to relate this number to theoretical and practical engineering facts.

Jan 1, 1971

By C. R. Forbes, J. C. Barton

Many different shapes of drill bits are in use with hammer drills, but little definite information is available whereby to judge which one of these shapes is the best. The following investigation was undertaken in order to determine what effect, if any, the shape of the cutting edge has on the cutting speed and wearing qualities of drill bits. The bits tested were those in common use, namely, the 4-point or cross bit, the 6-point bit, the Z bit and the "Carr" bit. The rock in which the tests were made was the red granite from southeast Missouri. It is a coarse crystalline granite containing an unusually large amount of quartz and is extremely hard, and on account of its uniform texture is admirably adapted to this work. While tests in other rocks might show somewhat different results, nevertheless it is the opinion of the authors that the relative cutting quality inherent in the shape of the bits would be the same in all rocks. Other qualities, such as mudding freely, freedom from fitchering, etc., might make one bit more desirable than another in softer rocks. Description" of Bits Tested &apos;I&apos;he 4-point bits were the usual shaped bits commonly made on the Leyner sharpener, with 14&apos; taper on the wings and a 90" angle between cutting edges. Some tests were run at 85 Ib. pressure with a 4-point bit made with a 50 taper on the wings; this bit was formed with the Carr bit dies. The 6-point bits were the usual shaped bits made on the Leyner sharpener. The Carr bits were made with a 5º taper and an angle of 100" between cutting edges.

Jan 1, 1918

By Clarence Hall, Spencer P. Howell

This bulletin deals with the characteristic features of the principal explosives used in mining and engineering operations, and espe- cially with the tests that show the suitability of different classes of explosives for different kinds of work. The Bureau of Mines pub- lishes the report as one of a series dealing with tests of explosives and methods of reducing the risks involved in the use of explosives in mining operations. The application of explosives to engineering and mining opera- tions has increased rapidly in recent years. According to a pre- liminary report issued by the Bureau of the Census, 469,000,000 pounds of explosives was manufactured in this country during the year 1909, and the greater part of this production was used for industrial purposes. In large engineering projects and in mining operations requiring the use of explosives the selection of a suitable explosive from the many varieties offered for sale is of fundamental importance. Vari- ous considerations are involved in the selection of an explosive of proper class for the blasting to be done. Many explosives suitable for quarry work are unsuitable for use in deep mines or in close workings. In metal mining and in driving tunnels the character of the gases evolved by the explosive on detonation is an important consideration. An explosive for use in gaseous or dusty coal mines must be formulated and compounded so that its flame temperature and the height and duration of its flame are reduced enough to per- mit its being used with comparative safety. In wet workings or in submarine blasting explosives impervious to moisture are requisite. In extremely cold climates explosives that do not require thawing are desirable, provided they are equally good in other respects. An essential requirement of all explosives, especially of those for use in tropical countries, is that they shall remain stable without change in chemical or physical characteristics.

Jan 1, 1913

Discussion of the paper of J. IV. GWINN, presented at the New York meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 239 to 247. GIRARD B. ROSENBLATT, Salt Lake City, Utah (communication to the Secretary*).-The storage-battery locomotive certainly has its place in metal mining and I an) glad to note that it is now receiving the recognition that is its clue. It is, however, not a panacea for all conditions of mine haulage. There are places where it will not work to advantage and cannot compare with` the trolley-type locomotive in cost of operation or in cost of maintenance. On the one hand, there are places where it clearly outshines the trolley-type locomotive. Much depends on the headroom available in the drifts and on the condition of the roof. For short hauls with moderate-

Jan 5, 1915

By P. Müller, W. J. Przybylowicz, V. M. Prozesky, D. de Bruin

"Abstract -The common style of gold mineralization in the Basal Reef and other auriferous conglomerates of the Witwatersrand Supergroup comprises clusters of gold grains occurring interstitially to quartz and pyrite pebbles as well as gold accumulations attached to the surface of and infilling hairline cracks and fractures in round, compact, detrital pyrite. The latter textural association is generally interpreted as a result of remobilization of originally detrital gold during regional metamorphism and related hydrothermal fluid circulation. There is general agreement that, although gold solubility was Iow, ore modification occurred during the metahydrothermal event, but uncertainty exists about the magnitude and scale of gold remobilization .Micro-textural and chemical investigation of compact round pyrite and associated gold accumulation has established that gold is preferentially deposited on chemically heterogeneous pyrite surfaces. Combinations of alternating high- and low-As zones in pyrite result in mixed np-type conductivity accompanied by electron exchange and the reduction-driven deposition of gold at the cathode. This mode] does not explain gold accumulations which are not immediately linked to chemical heterogeneities and it is inferred that an additional control on the deposition of gold was exerted by physical defects which lead to zones of increased charge density and/or areas of focussed conductivity. The inferred precipitation mechanisms suggest that submicrocopic physical and chemical controls are the important factors that determined the sites of gold nucleation and that precipitation mechanisms based on physicochemical changes of the hydrothermal system were not involved. The Basal Reef contains on average close to 5% of round, detrital, chemically zoned pyrite which provides a large number of electrochemically active pyrite surfaces. The extremely effective electrochemical precipitation mechanism together with the low solubility of gold in Witwatersrand fluids is the main reason for the spatially restricted remobilization of gold in the conglomerate reefs."

Jan 1, 1994

By Carel Robinson

THE little coal mine at Otsego, in the Winding Gulf field of southern West Virginia was dying. In the history of coal mining thousands of mines have been successful at first, but usually a change occurred and profits ceased. Often be change was so gradual and extended over such a length of time that the fundamental causes did not stand out in sharp relief and their significance was not realized. Studies often reveal that the cause for failure was in the arteries that connect the producing places with the mine entrance. Profits continued so long as the working places were close to the tipple and while the thrill of newness aid ease of access resulted in effective supervision from day to day. The air- way and haulageway, the wire line and manway, may have been sufficient when the distance from the entrance was a few hundred feet, but were inadequate when this was extended for thousands of feet.

Jan 1, 1937

I. N. KNAPP, Ardmore, Pa. (written discussion *).-The writer would first call attention to the fact that the mid-Continent field was credited from 1900 to 1915 with a production of about 641,000,000 bbl. of oil with-out any burdensome water troubles being reported. In fact, the authors say the conditions were not acute until about two years ago when the unusual conditions in the deeper oil fields were first encountered. The writer disclaims any personal knowledge of the district mentioned but, from the experience he has gained in directing drilling in various fields by both the cable-tool and the rotary methods and also in plugging and cementing wells, he fails to see how the analysis of water trouble given in the paper under discussion could be of any practical assistance in solving the problems so vaguely outlined. Possibly it might induce academic discussion, if not limited to practical operating conditions. A recent bulletin of the Bureau of Mines gives definite and practical statements that can be easily understood by one skilled in the art of drilling wells and heading off water troubles. From an operating standpoint subsurface knowledge must be based on logs of completed wells. Absolutely no one can have such knowledge as that indicated in Fig. 1 of the paper in question without drilling wells, and no one can question such facts when disclosed by the drill. Under classification of water the paper states "This water (primary) cannot be exhausted from the sands, but its encroachment can often be checked and so directed that wells need not be abandoned, until most of the available oil is secured." This is a live question to the writer. A couple of years ago he had some wells drilled and found the conditions comparable with sands A and D of Fig. 1 with B and C left out; but nothing in the paper, so far as can be found, indicates how this water encroachment is or can be checked or directed particularly under the High heads named.

Jan 5, 1919

By Lynn B. Hales, Randy A. Ynchausti

Introduction There continues to be a large economic opportunity associated with improving process performance through advanced process control systems within the minerals industry. The basis for this opportunity lies in the inherently low efficiencies of many of the unit operations found in mineral processing plants as well as the continual variation that is present in the ores being processed. The ageless target of such control systems is improved recoveries and concentrate grades, higher processing rates and lower unit costs. Many plants are enjoying the benefits of modem, well functioning process control systems but few if any have achieved plant-wide optimization in an economical sense. As new process modeling and control technologies, such as neural networks, continue to evolve and develop, the potential for plant- wide optimization is becoming a closer reality. Neural network technology appears to have a significant potential in the general field of process control and control of mineral processing operations. Neural networks are an emerging technology that have been evolving out of the study of biological systems since the early 1940&apos;s. The first software simulation of neural computing networks was reported in 1956 by Nathanial Rochester of IBM Research during the first conference on artificial intelligence which was sponsored by the Rockefeller Foundation. Neural Networks Neural networks can be considered to be a class of computer program that perform their problem solving functions based on a rudimentary model of the human brain and how it solves problems. Traditional computer programs and even computers themselves solve problems or process data sequentially and in a deterministic manner. The human brain, on the other hand, processes data and solves problems in a massively parallel fashion. We think of computers normally in terms of having a single processing unit, sometimes a co-processor to assist in certain activities such as mathematical functions or communications, bytes of memory, processing speed and program/data storage size.

Jan 1, 1992

By J. S. Bowles

DISCUSSION, M. Cohen presiding J. W. Christian (The Inorganic Chemistry Laboratory, oxford, Englandl)—I was very interested in Dr. Bowles&apos; results on the suppression of the transformation by solid films of alcohol or propane. The transformation in cobalt, which is also martensitic, can be explained by a mechanism involving the reflection of "half dislocations" down a series of atomic planes.* This reflection process is similar to that considered by Frank13 for plastic deformation on a single slip plane and, as he pointed out, reflection would be impossible if the metal were immersed in a liquid of higher density. It seems possible that solid films of alcohol have a similar effect on the lithium transformation. Reflection should also be possible at a grain boundary, though a higher kinetic energy of the dislocation, and hence a lower temperature would be required. As Dr. Bowles used coarse grained polycrystalline speci- mens, transformation on cooling should still have occurred in grains which did not form part of the outside (free surface) of the metal. This may account for the X-ray lines of the low temperature phase which were found. There is thus the interesting possibility that in a polycrystalline specimen a liquid, or in some cases a solid, film of material of or or higher density will lower M,, while in a single crystal it should suppress the transformation completely. In the case of cobalt it is necessary to find a dense liquid which will not react with the metal at the transformation temperature. The most promising liquid appears to be pure lead, but it is very difficult to devise a method of investigating whether or not this does suppress the transformation.

Jan 1, 1952

By J. J. B. Rutherford

IT is now well known that troublesome intercrystalline corrosion may occur in austenitic stainless steels following exposure of the metal to a temperature within the range 1000° to 1500° F. (540° to 815° C.). The present paper describes a satisfactory method of estimating the extent of such corrosion, based on the measurement of the electrical resistance of a specimen before and after attack. This new method enabled us to study quantitatively the effect of several factors upon intergranular corrosion in the 18 Cr, 8 Ni type of alloy. The results show that susceptibility to this attack increases with increasing carbon content and grain size and appears to pass through a maximum for certain combinations of temperature of sensitization and period during which the alloy was maintained at that temperature; and are in complete accord with our interpretation of the mechanism of this phenomenon. The method is probably applicable to other metals or alloys subject to intercrystalline attack, such as the aluminum alloys of the duralumin type. The methods hitherto in use for estimating the degree of intergranular attack fall into three types: (1) microscopic examination,1 (2) macroscopic examination of fractures, and (3) determination of the time required for complete failure or disintegration .2 None of these lends itself very well to a measurement of the extent of corrosion. The first two are qualitative in nature and the third provides an arbitrary value largely dependent on individual judgment, since failure is a progressive phenomenon and not a sudden event. Our experience is that weight-loss determinations, although valuable in some types of corrosion investigations, bear no simple relation to intercrystalline corrosion in this type of alloy, as is to be expected since the phenomenon probably involves only the thinnest films between adjacent metallic grains.

Jan 1, 1932

By John Hall

(New York Meeting, October, 1913.) THE Fremont test for measuring the energy consumed in breaking a notched bar of steel is not so well known in this country as it deserves to be. The test specimen used in this test is about 3/8 by 1/4 by about 11/4 in., notched with a hack saw on the lower side to cause the piece to break at a fixed point. A weight of 10 kg. falling 4 m., and provided with a knife or. chisel which strikes the specimen, breaks the test piece by impact. The residual force in the falling weight after it has broken the specimen is recorded by a suitable device, and the difference between the total energy and the residual energy of the weight (in kilogrammeters) is the force consumed in breaking the specimen. An experience of several years with the Fremont testing machine has shown its great value in readily detecting brittleness not revealed by tensile testing or slow bending testing. In this paper it is proposed to discuss (1) the supersensitiveness of the test as applied to cast steel and (2) its value in revealing the effect of heat treatment under certain conditions.

Jan 7, 1913

By J. W. Bawden, J. Nantel

"The mine operator has two prime objectives when he operates a mine: (l) the mine must be safe, and (2) the mine must operate with the lowest possible costs. The operator constantly faces a dilemma; if he is over cautious with regard to safety, his costs may be very high, and if he is over-zealous in trying to reduce costs, the safety of his operation may be jeopardized.Modern bulk mining methods rely heavily on high productivity non-entry stoping techniques (e.g. open stoping, VCR, etc.). Such techniques have the advantage of removing the operator from the active and sometimes dangerous mining face and ofminimizing costly development. On the other hand, this generally results in a certain loss of flexibility in following irregular ore-waste contacts. If stopes are opened too large and/or are inadequately supported, severe dilution with resulting escalating costs usually results. If initial access drift support is inadequate for latter mine induced stresses high rehabilitation costs may also be incurred.Optimization of stope dimensions should logically occur as part of a general mine rock engineering program, within the over-all mine planning context. The same program should help highlight those areas where drift rehabilitation may be a problem.Whenever successful mining is performed, rock engineering is being applied, either by design or by chance. The cost implications of planned practical rock engineering as an integral part of mine planning and design can be very significant to the ultimate mining ""bottom line"". At Noranda Minerals Inc. allowable stope dimensions are derived using a combination of numerical stress analysis and empirical design techniques. This paper discusses the use of the above techniques and their limitations as tools for rock mechanics based stope dimension optimization. The potential cost implications of such design efforts within the general mine planning context are also addressed."

Jan 1, 1989