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By G. T. Lineberry

Power requirements for a piece of mobile mining equipment are largely dependent on the set of conditions in which they must operate. These conditions are isolated and key parameters are identified. The effect of operating conditions on power determination is investigated. A simulation technique is developed to predict ranges of power demands for off-highway haul units as an archetype, permitting the analysis of changeable operating conditions. This program uses given data, conditions, and probabilities and ranges to solve for individual components of power, which can then be summed. By adopting such a technique, a systematic and rational determination of power is made possible. The usefulness of this basic approach in the determination of power requirements for other mobile mining equipment is emphasized.

Jan 1, 1983

By Herbert Haas

GEORGE W. HAWKINS, Tucson, Ariz. (communication to the Secretary*).-The paper by Mr. Haas will no doubt be followed with considerable interest, as it covers the power-plant problem in quite a comprehensive way, including not only the usual operating costs but also the fixed charges on the investment, and for load factors ranging all the way from 25 to 100 per cent. and fuel oil ranging from $1.25 to $2 per barrel. The very fact, however, that his paper does cover such a wide range of conditions, makes it the more imperative that any conclusion drawn from his analysis be very carefully considered for any specific case, for in making such analysis the type of prime mover and size must be selected for some one condition which might not be the proper selection had some other condition been assumed as the basic one, resulting in an unfavorable comparison under all conditions except that condition assumed. From the reasons given by the author for his selection of the large turbine units, it is evident he had in mind very high load factors, ranging

Jan 12, 1916

By Walter Wood

The specifications for cast-iron pipe that have been submitted at this meeting are practically the outgrowth of those which were originally adopted, about 1860, by Mr. Kirkwood of Brooklyn, N. Y. They have been changed but little since that time, the mode of testing pipe in the hydraulic press, as well as the method of coating, not having departed from the original practice. The chief addition to the specifications has been in the adoption of a test-bar 2 in. by 1 in. in crosa-section, broken between 24-in. supports by a transverse strain applied on the flat side. Test-bars were first introduced into pipe-specifications about 1870. At that time a satisfactory test-piece had to stand a tensile strain of 16,000 lb. per square inch. The present test-bar was adopted in order to give some idea of the deflection of the iron that was being used. These deflection-tests have been so satisfactory to both engineers and manufacturers, and have met the requirements of the pipe-trade so accurately, that it is considered best to hold to the . 2-in. by 1-in. bar instead of adopting the short " Arbitration Bar," which yields but little information from the stand-point of deflection. The new feature in these specifications is the effort to reach standards to which pipe shall be cast in the future, thus permitting the manufacturer to make up stock and the purchaser to find material on hand when he asks for deliveries. Heretofore there has never been ally standard weight for pipes? although in some sizes certain weights are more frequently asked for than others. The fixing of standards for pipes permits the adoption of definite standards for fittings. It has been aimed to secure such uniformity for fittings as will permit the same class of fittings to cover two or more classes of pipe. In order to accomplish

Jan 1, 1905

Following the usual custom, three meetings are planned for the year. The Mid-Continent meeting will be held at Oklahoma City, Okla., Oct. 7 and 8, and the California meeting is planned for Los Angeles, probably also early in October. A program along the usual lines is under way for the annual New York meeting. Discussion and planning of the year's activity started in March. An effort is under way to secure papers dealing with some overlapping phases of engineering, petroleum geology, geophysics, law, economics, refining, etc. The main reason for attempting a program along these lines is the belief that unusually interesting technical papers can be obtained. The degree of specialization in the technical and related fields has permitted but few individuals to develop a sufficiently comprehensive viewpoint. Also, at times the developments in a particular field are capable of giving great stimulus toward much needed solutions of difficult problems in others fields of activity. With the coming of the period of restriction of production to market demand, many changes have occurred in policy and technique of petroleum production. Some changes have been advances, others have been of retrograde nature. It seems doubtful whether the adjustment to the condition of excess producing capacity has been complete or sound in some major respects. Many changes are in progress and others need to be initiated. The industry has excessive producing capacity so far as immediate market demand is concerned, but reserves for several years hence are generally believed insufficient. Exploration and discovery should go forward but development should proceed with caution and under control. Property rights should be clarified and protected for the new condition— without excessive cost for drilling wells that serve no purpose except that of giving some protection to property rights at the cost of an increased price to the consumer. Under the more steady condition of assured supply for the immediate future, as compared to the hand-to-mouth condition of wide-open production, a greatly advanced technique of development and production is possible and is being developed. Great progress has been made, but much remains to be done. Along some important lines progress can be effected only by better understanding between the engineer and the geologist, the lawyer, the politician, the geophysicist, etc. There is need

Jan 1, 1937

By Felix Wunsch

WHILE the effect of the cold-junction temperature has been known by many, its consideration has been ignored in a number of installations, resulting at tunes in a very considerable error. In fact, the magnitude of this error may amount to over 100° in some cases. While hand-operated correcting devices for portable checking pyrometers may be entirely satisfactory, it is, of course, desirable to have such apparatus en¬ Millivoltmeter Thermocouple Platinum Wire Mercury FIG. 1.-EARLY `METHOD OF AUTOMATICALLY COMPENSATING FOR COLD-JUNCTION TEMPERATURE CHANGES. tirely automatic, when applied to curve-drawing or printing pyrometers, otherwise there is no assurance that the record is correct. Numerous methods for automatically compensating for cold-junction temperature changes of thermocouples have been proposed and used in connection with millivoltmeters. One of the earliest proposed was that shown in Fig. 1. A bare resistance wire was immersed in a column of mercury located near the cold junction of the thermocouple. An increase in temperature near the cold junction resulted in a rise of the mercury column, which short-circuited more of the resistance wire causing an increase in the potential difference across the millivoltmeter, which compensated for the decreased electromotive force of the thermocouple.

Jan 9, 1919

By R. L. Slobod, H. A. Blum

A semiquantitative method for measuring the wettability of reservoir rocks has been developed. These data are needed for reservoir analysis and for interpretation of laboratory displacement studies. The wettability of a core sample is measured by the contact angle for the system oil-water-solid. These contact angles are calculated from the displacement pressure (threshold pressure) obtained by use of the centrifuge, using first oil-water and second air-oil in the same core sample. This method is based on the assumption that the air-oil and oil-water interfaces occupy similar positions in the porous medium when desaturation of the wetting phase is initiated. The assumption is also made that the Contact angle for the air-oil-solid system which is close to zero in value does not change appreciably even when the contact angle for the oil-water-solid system experiences marked changes. "Apparent contact angles'' for five different solids ranging from 31" to 82" have been determined, and changes irr the "apparent contact angle" of a given sample with laboratory use from 33" to 53' {lave been observed. INTRODUCTION Reservoir rocks vary in their wettability, 1,2,3,4 some being preferentially water wet while other are apparently preferentially oil wet. The degree of wettability, in theory, is measured quantitatively by the contact angle for the system solid-oil-water, hut in 1)practice this quantity is extremely difficult to determine." The need for obtaining some measure of this quantity has become obvious in recent years as a result of both laboratory. and field observations. Several reservoir.: such as the Bradford Sand in Pennsylvania and the Wilcox' at Oklahoma City are reported to be oil wet. If these report:: correctly reflect the true nature of the surface of the rock in the ground, then these reservoirs probably will not perform as predicted on the basis of a water wet rock. In the laboratory many core samples have been Observed to be oil wet. These samples, while perhaps not correctly representing the reservoir, have markedly different properties from water wet rock. The location of the phases is different (oil is in contact with rock instead of water), and other quantities such as the connate water, the capillary pressure curve; residual oil. relative permeabilities. and the recovery of oil by water flooding are markedly affected by the value of the contact -4 A further complication observed in the laboratory is the chang-ing of the wettability of a rock specimen with use. such changes mean that repeat runs on the same core are not the duplicate tests desired, but represent new experiments on a more oil wet material. The changes in surface characteristics are sometimes so rapid that by the time an experiment requiring several days is completed, the results may not be representative of the core as originally described, The, rock material itself (Silica. carbonates. etc.), whell Clean and uncontaminated, is water wet. There seems b( : little evidence of the presence of oil wet minerals such as heavy metal sulfides. The oil wetness of reservoir samples, therefore, is believed to be caused by the accumulation of an adsorbed film in which the polar group of a large organic. molecule is adsorbed on the surface leaving the organic or hydrocarbon part of the molecule projecting out from the solid. Such a surface is much more readily wet 17" oil than by water. These considerations indicate the need for a method which will provide some measure of tile wettalbility (Contact(angle if possible) for reservoir rock ..samples) The method should be capable of (1.1 distinguishing between tile wettalility of dif. ferent formation,.. (2) detecting (change. ill wettalbility of a core with use. and (3) measuring the changes in Wettability which may be accomplished with cleaning operations. such as the use of sodium silicate for increasing water wrettalbility." A preliminary report on such a method is preseted below. not with the idea that this procedure alone will Solve the wettabil-ity problem. but rather that it may provide encouragement to

Jan 1, 1952

By Ross Glanville

INTRODUCTION The Optimum Production Rate (OPR) is one of the most important parameters in the evaluation of a mineral deposit. The OPR can also be expressed as the Optimum Mine Life (OML) in years since the expected mine life is determined by dividing the OPR per year into the estimated ore reserves. Unfortunately, very little time and effort has been directed towards the determination of the OPR. Instead, "rules of thumb" are often applied to select a mine life without due consideration of the economic implications of such a selection. A "justification" for a particular production rate is often based on a pre-conceived arbitrary requirement for a mine life of 5, 10, or 15 years, for example. In this paper it is demonstrated that such arbitrary selections for high-grade/low-tonnage mines (such as many underground gold/silver deposits) often lead to sub-optimal results. In fact, an apparently uneconomic deposit at an arbitrary production rate may be economic at the OPR. Consequently, investment opportunities may be overlooked if one analyzes mine properties based on arbitrary production rates. This paper analyzes the interrelationships of variables such as production rates, capital and operating costs, cut-off grades, discount rates, metal prices, etc. The analysis shows that the OML for high-grade/low-tonnage deposits is often in the range of two to four years. Although such mine lives intuitively appear too short to many individuals, it should be noted that, in the past, much of the mining industry became familiar with the economics of large scale mining operations. The rules of thumb developed for such large scale operations should not be applied to high-grade/low-tonnage mines such as many of the underground gold deposits. DEFINITION OF OPTIMUM PRODUCTION RATE The OPR is selected on the basis of maximizing the net present value of the after-tax cash flows. However, as discussed later in this paper, the production rate selected for a particular mine may be somewhat higher or lower than the theoretical OPR as a result of other variables such as: 1) the probability or expectation of additional reserves being discovered 2) the likelihood of being able to custom mill nearby deposits owned by others 3) the configuration or attitude of the orebody, which may place upper limits on the production rate 4) the residual, or salvage values, of the mine/mill facilities COMPARISON BETWEEN DIFFERENT PRODUCTION RATES For an orebody with definite physical cutoffs*, or boundaries (such as faults or unconformities), the total ore reserves at different production rates may be identical. Consequently, for such an orebody, varying production rates result in differing mine lives. Although the metallurgical recoveries, the mine dilution, and other similar physical parameters may vary slightly at different production rates, the major differences are the capital costs and operating costs per ton. The ramifications of these differences are especially important at low production rates (up to approximately 1000 tons per day), but can also be significant at higher production rates.

Jan 1, 1985

By W. S. Stahmann, F. W. Bowdish

Previously published experimental data showing that both collectable and non-collectable sulfide films may be formed on chrysocolla were analysed, and chemical mechanisms were proposed for the formation of the films. A special technique was developed by which the quantity of sulfur adsorbed was determined for samples sulfidized under different conditions of pH and soluble sulfide concentration. The data on sulfur adsorption were used together with the expression for the equilibrium constant for the proposed reaction to indicate the validity of the chemical mechanism theory. A recent paper 1 about contact angle studies on chrysocolla reported the effects of pH value and sodium sulfide concentration during sulfidization upon the character of the surfaces produced. In each experiment the surface of a specimen of chrysocolla was prepared by grinding it with fine abrasive and washing it in tap water. The specimen was then placed in the sulfidizing solution for 10 min, rinsed in tap water, treated for 15 min in a solution containing 30 mg of potassium amyl xanthate per liter, rinsed in distilled water, and tested for air adhesion in a contact angle apparatus. The results, when plotted as in Fig. 1, showed an island representing conditions giving air adherent or collectable surfaces surrounded by conditions giving non-collectable surfaces. Particular interest may be attached to the region of non-collectability to the right of and above the island in Fig. 1, and to the boundry curve separating these two regions. It is apparent that at any pH from 4.0 to 6.0, where a collectable surface may be produced, a sufficient increase in the sulfide concentration results in a non-collectable surface. Thus it appears that too much soluble sulfide has a depressing effect upon the mineral, just as it has in sulfide flotation. This paper presents some speculations regarding the chemical mechanisms by which the collectable and non-collectable sulfide films may be formed and reports on a physical-chemical study intended to support these speculations. THEORETICAL CONSIDERATIONS The experimental results presented in the previous paper were analysed in several ways in an attempt to understand better the chemical mechanisms involved. For several points on the boundary to the right of the region of contact in Fig. 1, molar concentrations of H+, OH-, HS-, and S= ions, as well as various ion concentration products, were calculated. Following the reasoning of Wark and Cox, 2,3 no single kind of ions may be credited with causing depression of the surface because none of them have a constant con-

Jan 1, 1968

By Louis Moyd

In the preparation of illustrations to accompany reports of investigations concerning particle shapes of various natural and manufactured materials proposed for use as fine aggretates in concrete structures, it was found that stereoscopic views of such materials presented the information much more effectively than the usual two-dimensional photographs. With the whole-hearted cooperation of the Photographic Section, a technique was developed in the petrographic laboratory of the Concrete Research Division, U.S. Corps of Engineers, at Clinton, Miss., for simple and rapid preparation of paired stereoscopic photographs and micrographs. The method requires only equipment which is usually part of the general stock of any laboratory, and it is adaptable for all purposes in which three-dimensional views would be found superior to ordinary photographs.

Jan 1, 1949

By Samuel E. Doak

The utilization of rotary kilns, of the well-known cement type, for the preparation of iron ores for the blast furnace, has become of considerable economic importance within the past 10 years in certain localities, notably those where the native ores are lean. Such kilns may be used simply for the agglomeration of ores too fine to be charged into the blast furnace (i.e., ores whose, loss in the dust catchers is excessive, and whose fineness is detrimental to the working of the furnace), or for the desulphurization of lump and fine ores the sulphur content of which does not exceed 6 or 7 per cent. The desulphurizing action can be combined with that of agglomeration provided the kiln is sufficiently large. Other processes have been developed for the same purpose, but while I am not able to draw a comparison between them by reason of lack of sufficient data, it is safe to say that the kiln, if properly dimensioned for the character of ore to be treated, will compare favorably in its results, both as to economy and quality of product, with any other process. It is not, however, as well adapted for the treatment of flue dust as is a sintering operation, on account of the large percentage of fine coke contained therein. Any combustible entering the kiln at its feed end renders the process very much more expensive and unsatisfactory on account of the difficulty of controlling the temperature, also because of the rapidity with which long "rings" form, due to the increased heat at the cooler end of the kiln. The greatest value of the kiln at present is in the treatment of pyrites cinder; that is, the residue from pyrites ore after the extraction of the greater part of the sulphur. This cinder, while high in iron content, has too much sulphur remaining in it to be allowed to form a large part of the blast-furnace burden, without further treatment. It will range in metallic iron from 42 per cent., representing a very low-grade cinder from a domestic pyrites, to 64 per cent. of the residue from the best Spanish ore, and the corresponding silica content will vary from the maximum of about 25 per cent. to 11/2 per cent. The residual sulphur depends largely on the type of burner used in the original desulphurization. In general, the leanest original ores retain the greatest amounts of sulphur. In modern practice the percentage of sulphur in the cinder is rarely as great as six, and seldom lower than one and one-half. Average analyses for iron, silica, and sulphur of the cinders that have come under my personal observation are as follows:

Jan 1, 1916

By W. Fletcher, R. C. Schenk

This paper outlines a well proven and highly successful approach for eliminating many of the problem and frustrations often experienced in plant startup. The approach was developed over a period of 25 years during which some 90 plants were commissioned. This paper discusses startup from the contractor’s perspective and highlights the requirement for detailed startup planning, careful coordination during the project final construction phase, and thorough checkout of equipment prior to introduction of feed. Performance of these services has demonstrated a valuable opportunity exists for the contractor to assist in the training of the plant operating personnel.

Jan 1, 1983

By J. M. Lohr

THE characteristics and uses of thermocouples of platinum and the platinum alloys being so well known, this paper will be confined to base-metal couples. During the past decade, there has developed a strong demand for thermocouples made of metals cheaper than the platinum alloys, and suitable for industrial heat measurements. Much research has been clone but only a very limited number of alloys have been found to possess the necessary characteristics for general technical use. In the development of thermocouple alloys it is necessary to consider the following points: The electromotive force and temperature relations; permanency or constancy; reproducibility; manufacturing difficulties; durability; and accuracy in use. The electromotive force developed by the thermocouple should increase with the rise of temperature according to some definite law. It is desirable that the electromotive force should vary directly with the temperature difference of its junctions, in other words, giving a curve linear or nearly so. It is also desirable that the resulting electromotive force be as large as possible for any given range of temperature, thereby insuring greater accuracy of readings.

Jan 9, 1919

By Thomas W. Yardley

In many years' experience as a maker and purchaser of cast-iron coated pipe, I have never met with any standard form of specifications for such. Each water-works company, employing a hydraulic engineer, has, under his direction, prepared complete specifications for the particular conditions required; but I cannot find that any two are alike; and each foundry, in bidding for the supply of such pipe, makes the price to cover the conditions' required. I, therefore, have the honor of offering to the Institute a form of specifications for cast-iron coated water-pipe, that may be found useful to water-works companies and others requiring pipe of this kind. The conditions are all reasonable, and can be carried out by makers without additional cost, and with advantage to the purchaser. Section 1 gives the kind of pipe, with its general characteristics. Section 2 specifies that neutral pig-iron shall be used, since such iron possesses the strength required, and is uniform in its shrinkage. Section 5, requiring makers to give the brands of pig-iron used

Jan 1, 1890

By Kjell Lidin, Christer Nordström

INTRODUCTION LKAB produces iron ore in several mines in northern Sweden, and has been doing so for nearly 100 years. Total production to date is 600 million tonnes of finished products of various kinds (pellets, lump ore, fines). Close to 400 million tonnes have been produced by sublevel caving. This method has been the company's standard method for more than 20 years. A review of the development of equipment over the past 15 years and an outlook up to about 1990 leads to the following general re- flections concerning probable trends. Trends for all equipment are increasing precision and stricter environmental requirements will necessitate cabs, remote control etc to an increasing extent. Conventional sublevel caving can be broken down into the following unit operations: 1. Planning incl prospecting drilling. 2. Horizontal drilling. 3. Fan drilling. 4. Charging and blasting. 5. Loading and haulage at sublevels. 6. Ore drawing in chutes. 7. Rock reinforcement. 8. Production service. This lecture will deal in brief with each of these unit operations and the trends we are experiencing for them. A number of slides illustrating equipment

Jan 1, 1981

By J. E. Tobey, David R. Mitchell, J. H. Kerrick

DETAILED knowledge of purchase specifications established by coal consumers is essential to the successful design and operation of a coal preparation plant. ANTHRACITE Specifications should be considered by both the consumer and the producer as guide posts outlining a certain path for both to follow. Plants differ, therefore specifications must differ to meet the varied requirements. Specifications are not of themselves a "cureall" or an assurance of complete satisfaction in fuel utilization. Specifications should not be regarded as a license to engage in an orgy of buying any and all coals that may happen to fall within their limits. This would lead to the indiscriminate mixing of coals which may vary in their burning characteristics. Different coals of equal grade tend to be individualistic in their burning characteristics. Rather, specifications should be used to help simplify coal selection, to reduce the actual number of coals used over a given period; in other words, to have a stabilizing influence on coal or customer turnover. In the final analysis, the use of too many coals per year in a plant is costly to both the consumer and the producer. Too many sources usually result in higher operating and maintenance costs for the consumer and higher sales costs for the producer. Finally, the statement included in the report accompanying the comprehensive Coal Selection Charts prepared by the Coal Committee of the National Association of Purchasing Agents, and released in 1938, is significant. This Committee worked diligently for a period of 15 years seeking to find a scientific and reliable method for selecting coals. The two following paragraphs are quoted from its report: More important is the fact that no ready-made classification or set of specifications can possibly replace the judgment and resourcefulness of an experienced combustion engineer or fuel technologist, nor the usual need for full scale plant tests under the exact conditions of use before a final decision is made.

Jan 1, 1950

By J. E. Tobey, David R. Mitchell, J. H. Kerrick

DETAILED knowledge of purchase specifications established by coal consumers is essential to the successful design and operation of a coal-preparation plant. ANTHRACITE Specifications should be considered by both the consumer and the producer as guide posts outlining a certain path for both to follow. Plants differ, therefore specifications must differ to meet the varied requirements. Specifications are not of themselves a "cure all" or an assurance of complete satisfaction in fuel utilization. Specifications should not be regarded as a license to engage in an orgy of buying any and all coals that may happen to fall within their limits. This would lead to the indiscriminate mixing of coals which may vary in their burning characteristics. Different coals of equal grade tend to be individualistic in their burning characteristics. Rather, specifications should be used to help simplify coal selection, to reduce the actual number of coals used over a given period; in other words, to have a stabilizing influence on coal or customer turnover. In the final analysis, the use of too many coals per year in a plant is costly to both the consumer and the producer. Too many sources usually result in higher operating and maintenance costs for the consumer and higher sales costs for the producer. Finally, the statement included in the report accompanying the com¬prehensive Coal Selection Charts prepared by the Coal Committee of the National Association of Purchasing Agents, and released in 1938, is significant. This Committee worked diligently for a period of 15 years seeking to find a scientific and reliable method for selecting coals. The two following paragraphs are quoted from its report: More important is the fact that no ready-made classification or set of specifications can possibly replace the judgment and resourcefulness of an experienced combustion engineer or fuel technologist, nor the usual need for full scale plant tests under the exact conditions of use before a final decision is made ...

Jan 1, 1943

By J. W. Smith

Our continuous search for underground productivity improvements has been brought about by the diminishing ore grades in existing underground mines. The need for more efficient mining methods is a result of the economic problems facing our industry today, and this has caused us to evaluate underground haulage methods which have traditionally been the "bottleneck" in the flow of material from the ore in the natural state to the surface processing facility of any underground mining operation. Small improvements in the face haulage systems have yielded much greater benefits as they relate to overall mine productivity so it's only natural that we are all concerned with the best method of moving ore from the face to the main line haulage. In a recent paper titled "Underground Haulage Trucks - Gaining Momentum Worldwide", Richard A. Thomas concludes that the use of trucks to haul ores in underground mines is on the increase spurred by the convergence of a number of technology advances and economic realities. Perhaps the most important stimulus for the growth of trackless haulage is the high degree of haulage flexibility in underground operations. On the economic side, the demand for higher productivity from underground mines has resulted in larger physical dimensions of haulage roads, that is, higher backs and wider drifts to provide more room for high capacity haulage units. In the process of determining the most effective type of equipment for haulage, the power source must be a major consideration. For the purpose of this paper, we will limit the comparison to rubber-tired trackless haulage vehicles and not try to make a comparison between rubber-tired haulage, continuous haulage systems and rail-mounted haulage. Cost is perhaps the only really measurable factor when making a comparison between electric and diesel haulage. You will find that some costs will be very well defined in absolute terms. In other areas of comparison, cost can be fairly well estimated, and yet in still others, the costs are totally arbitrary. Let's take a look at some of the cost considerations. (Figure 1) first of all, is the initial cost of the equipment. This capital cost quite often is a determining factor in the type of haulage vehicle to be selected, yet this initial cost is perhaps the most insignificant of all costs when evaluating an operation over the long term. Of much greater concern, is the cost of maintenance. This cost will often run three times the original capital investment during the life of a single piece of haulage equipment. This factor can include rebuild to extend the life of the original capital investment, but certainly includes the labor and materials necessary, plus the inventory to keep the equipment in good repair. Perhaps one cost which is now playing an even greater role in the rubber-tired haulage operation, is the cost of fuel. Conoco has recently come up with some rough estimates which indicate that diesel fuel will cost an average of three times the equivalent kilowatt output in direct electric power. Diesel fuel is almost twice the cost of stored electric power. (This of course relates to the efficiencies of charging and recovery of power from lead acid storage cells.) These particular figures of course will vary from one area to another but I think that there is enough significance here to certainly warrant the further study of fuel costs for each particular area or mine. Another cost is breakdown expense. This must be treated differently from maintenance costs because a potentially larger expense is involved, more than just parts and labor. Now we have to deal with the cost of lost production time, which can have a much greater overall effect. Mine plan economics are another cost consideration where we can't make a comparison without looking at specifics. Here you must look at the movement of power centers vs. the flexibility and freedom of movement of vehicles. The determination must be made as to what types of equipment will fit into any predetermined mine plan and if a change in the planned roadway dimensions for the mine plan itself would be more economical so that more efficient type of equipment could be utilized. Finally, two of the most important aspects to be considered with potential ramifications far beyond what we have mentioned previously, is the cost of health and safety, which is really the cost of meeting current and future government regulations, reasonable or otherwise. And of course, when making any consideration here it is impossible to come up with anything more than an educated guess on the cost of meeting the new regulations. Now let's take a look at some of the advantages of diesel vehicles as well as advantages offered by electric vehicles, both battery and cable powered versions (Figure 2). Much of the data used in this comparison is based on experience with three vehicles manufactured by Jeffrey Mining Machinery Division, Dresser Industries. Jeffrey manufactures all three types, each with approximately a 15-ton capacity, even though few of these Jeffrey vehicles are used in uranium mining operations. Much of our experience comes from the 4114 diesel powered RAMCAR which is a 4-wheel drive, articulated steering,vehicle powered by a Caterpillar 3306NA engine and using a powershift transmission. This will be compared with the performance of the Jeffrey 404H battery powered RAMCAR with articulated steering which utilizes a separate 35 HP DC drive motor on each of two wheels with solid-state speed controls, and the final comparison will be made on the Jeffrey 4015 cable-reel shuttle car which is powered by two 60 HP constant

Jan 1, 1982

By Robert J. Brison

On the basis of experience accumulated during the completion of some 150 gold/silver process development projects, general guidelines are presented for developing the most cost effective process for a specific project. Steps involved in process development for lode ore deposits generally include a review of pertinent background information on the ore deposit, sample procurement and preparation, sample characterization, study of concentration possibilities, investigation of leaching and metal recovery methods, economic evaluation of alternative processes, optimization of the selected process, a pilot plant program if warranted, and finally, process design and feasibility studies. Each of these steps is discussed, with emphasis on the relation between technology and economics.

Jan 1, 1984

By John Tyssowski

IN 1925, Harry Howard Stout, then metallurgist for Phelps Dodge Corporation, while investigating the cleaning of cathode copper by various gases at elevated temper-atures below the melting point of the metal, observed in the laboratory that particles of pure copper heated in a closed tube filled with hydrogen seemingly "stuck together." By further investigation he found that there was actual crystal growth across the boundaries of the particles of pure metal; in other words, there was a complete new crystal realignment and growth throughout the newly formed copper mass. It was coalescence, not adhesion; the several parti-cles had become one unit. From this dis-covery has been developed the coalescence process, whereby copper of cathode purity is squirted out in semifabricated form from an extrusion press, by the appli-cation of about 30c0 tons pressure on a 10-in. piston. Stout decided that cathode copper pro-duced by electrolytic deposition was the logical source of the pure copper required for the coalescence process, but as there was no way of reducing the ordinary tough commercial cathodes to the small particles required he was confronted by a serious problem at the outset. Under his direction, this problem was solved by William H, Osborn and Harry Howard Stout, Jr. They developed the process and technique for producing cathode copper in brittle, friable form, and to them must be given the greater part of the credit for this phase of the development program as well as for that relating to the gas cleaning of the cathode particles.

Jan 1, 1940

By E. P. Mathewson

(Butte Meeting, August, 1913.) IN a discussion -of a paper on " The Basic Process as Applied to Copper Smelting," by Percy C. Gilchrist, read before the Society of Chemical Industry, London, Jan. 5, 1S91,1 Prof. W. C. Roberts Austen asked Mr. Gilchrist whether he thought that the substitution of a basic lining for acid lining in the Marshes process would afford anything like the service which it had been shown to render in the metallurgy, of iron. Claude Vautin stated that he had experimented for over two years with basic linings for Bessemer converters for copper mattes at Cobar, but had given up the attempt on the score of cost. Mr. Gilchrist in his reply stated that he did not believe in applying any system of Bessemerizing to copper. About the time of the presentation of the paper mentioned, Herman Keller, Superintendent of the Parrott smelter, in Butte, was experimenting on a large scale with converters lined with magnesite brick. He gave up the idea on account of the cost of linings and because no particular advantage was observed. My belief is that his tuyeres and converters were -too small. A short time; afterward similar experiments were tried at the Great Falls plant of the Boston & Montana Co., said at the Old Works of the Anaconda Copper Mining Co. in Anaconda. These were abandoned on the score of cost and the lack of advantages. The same cause of failure, in my opinion, holds here. The Anaconda Copper Mining Co., however, adopted the magnesite brick lining for its tilting casting machines.

Jan 6, 1913