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By Sidney W. Poole

THE control of deoxidation, together with other factors involved in electric-furnace melting practice, to consistently produce heats of high-quality alloy steel to stringent specifications as to nonmetallic inclusion content is a problem of considerable magnitude. Steel melting as an industrial process is subject to many variables that can influence the quality of the product made. In order to modify the size, amount and distribution of inclusions and to promote their elimination, deoxidation, among other practices, plays a major part. The primary purpose of deoxidation in the production of electric-furnace alloy steels is the removal of dissolved oxygen present as FeO in the bath, which is produced as a result of prior oxidizing conditions. The elements usually added to effect this removal of soluble oxygen are those that will, upon addition, cause the formation of an oxide compound insoluble in the molten steel bath as silica, alumina or silicate combinations.

Jan 1, 1947

By N. H. Parker, J. G. Papailias, G. Gutzeit

In its many forms, the turbine has greater latitude of application than any other mixing device. It is readily adaptable to all tank shapes, from the shallow pan to the tall and narrow stovepipe. Although turbine mixers can be adapted to most tank conformations, experience has shown that there is a preferred shape for optimum efficiency in each service. In the accompanying drawings this relationship is illustrated by the shallower tank for slurry suspension. The taller tank is preferable for continuous staged systems, or maximum retention of the gas phase in absorption. No single turbine covers the entire range of these applications with maximum efficiency. The back-sloped blade offers maximum power economy. The straight blade develops a higher discharge velocity for the dispersion type of service requiring localized shear. The same high shear environment is provided by the back-sloped impeller with stator ring assembly, which permits the most positive discharge control, Fig. 1. Positive stream control is critical in solids suspensions.

Mar 1, 1956

By Yoon T. Auck, Milton E. Wadsworth

Column leach studies of two low grade prophyry copper ores were made with variables of size, flow rate, pH, drainage rate and tempature. Evidence is presented to show that, in some types of ores, sulfide minerals block leaching channels and regulate the rate of dissolution of gangue constituents. Basic iron sulfates, dissolved by introducing acid, provide oxidizing agent in the form of ferric ion in the absence of oxygen. Ferric ion then acts to release copper from the ore. Oxygen up-take was found to increase with the lowering of the pH and to follow parabolic kinetics attributable to the precipitation of basic iron salts within the pore channels. Slow drainage of residual gravitational water can seriously retard oxygen up-take during oxidation for particles in the coarse sand range. A model is presented for dump leaching in which a reaction zone connected by channels to the surface of the ore particle moves topo-chemically during the course of the reaction.

Jan 1, 1973

By J. J. Rutledge

THE first method of working coal mines in the middle western states, more particularly in Illinois, Indiana and Missouri, was by means of the so-called single-entry method. In this method a single main passageway, or entry, was driven in the coal seam. with no parallel passageways, and from this pas-sageway or entry there were turned at intervals sim-ilar cross-passageways or entries, and from these cross-passageways, if the coal seam worked lay fairly horizontal, rooms were turned right and left. These crude methods of working were followed when the com-panies opening the mines were small and of very limited capital, and when the demand for coal was small and irregular. The principal desire was to produce coal in the short-est possible time and at the cheapest price. The chief evil resulting from such method of working was de-fective ventilation, although there were other serious drawbacks. There were then few or no good mining laws and no restrictions on those operating the coal mines. The hours of labor were long, the wages low, and the miners accordingly worked hard. All the coal was either sheared or undercut with a pick by hand. Very little solid shooting and no machine mining was done. What little air entered the mine, openings was introduced through the entries or. headings and thence conducted through the rooms by means of curtains; in many cases, as the workings became more exten-sive, the number of curtains added so materially to the mine resistance that ventilation was extremely in-efficient. Shots were fired by the miners at any time during the working shift and consequently there was more or less powder smoke or fumes in the mine work-ings all day long. Moreover, the working days were much longer than at present. The fine, dry coal-dust falling from the miners' picks while they were shear-ing or undercutting the coal filled the mine atmosphere and was taken into the lungs of the mine employees.

Jan 2, 1927

By John Primrose

TUBE stills having demonstrated their usefulness for refining operations, the later developments in their design have been in the direction of improved thermal efficiency: The earlier designs operated with low furnace temperatures and large volumes of furnace gas because the fuel was burned with much excess air. It was quite possible to provide sufficient heating surface to lower the temperature of the flue gas to within 150° of the temperature of the inlet oil, or when inlet-oil temperatures were high to have the flue gas escape at 300° or 350° F. by using the heat remaining in the flue gas from the still to preheat the air supplied for combustion. But even so, the thermal efficiency was low because of the large quantity of air used for combustion. The large quantity of excess air was required to burn the fuel in the furnace at a temperature low enough to prevent overheating the furnace walls and overheating of the oil. Supplying heat to the tubes of the heating surface at a rate beyond the capabilities of the oil to absorb, except with a considerable difference between the temperature of the inside of the tube and oil passing through, would result in overheating the tubes and the oil in contact with them. For these reasons it was very necessary in the older types of tube stills to burn the fuel with large quantities of excess air, resulting in low thermal efficiency despite the low flue-gas temperature. Neglecting loss by radiation, the thermal efficiency could be improved only by burning the fuel with less excess air, but it was necessary to accomplish this without upsetting the furnace temperature conditions existing when large quantities of excess air were used. There are several methods of bringing this about, such as controlling the furnace temperature by returning a proportion of the flue gas to the furnace, or by exposing direct to the fire a heat-absorbing surface so located and proportioned that sufficient heat will be absorbed by radiation to prevent excessive furnace temperatures.

Jan 1, 1928

By Haakon Styri

IN discussion of Dr. Fitterer's paper on electrolytic separation of slag inclusions, some results from experiments on electrolyzing high-carbon steels at the SKF Research Laboratory were given.1 We had been working for a number of years on chemical methods of separating the inclusions but could not find any solvent that would dissolve the steel without attacking some of the inclusions, particularly the sulfides in which we were mostly interested at the time, nor any that would dissolve all sulfide or silica in filings as fine as 300 mesh without attacking the iron. Electrolytic methods had also been tried without any real progress until we learned from the Bureau of Mines about the use of the collodion membrane around the anode. Our early difficulties were to some extent different from those of the Bureau of Mines, perhaps because of experimenting on steels of higher carbon content, but most of our difficulties were of the same nature as those of the Bureau. Formation of large quantities of basic hydroxides use of impure and oxidized ferrous sulfate. To protect from oxidation from the atmosphere during electrolysis, after purer chemicals were obtained, a thin layer, 1/8 in. or less, of molten paraffin was poured over the surface of the cathode liquid, where it solidified. It was found desirable also to hold the cathode chamber slightly acid by initial addition of 0.1 per cent acid (sulfuric or hydrochloric) to prevent precipitation of the hydroxide. This acidity would decrease gradually and the cathode chamber would become neutral before the end of the electrolyzing. The increase in acidity in the anode chamber during our early experiments had appeared to cause attack of the precipitated sulfides in the residue, which originally was analyzed by volumetric method for sulfur, and for this reason a 10 per cent sodium citrate solution was substituted for the sulfate in the anode chamber.

Jan 1, 1932

Discussion of the paper of DORSET A. LYON and ROBERT M. KEENEY, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin. No. 92, August, 1914, pp. 1791 to 1800. LAWRENCE ADDICKS, Chrome, N. J.-I read this paper for the first time this afternoon, and it is really worthy of a much more careful reply than I can make with such a short time to consider it, but I just want to say that I differ with Dr. Lyon in his premises and conception of what happens in a refining furnace. He cites steel as an instance where the production of special grades justifies the high cost of power in an electric furnace, and goes on to say the same will be true in the case of copper, for the reason that you will get a better quality of product. I don't think you will get a higher grade of copper,. or a better conductivity, as I will explain in a moment. The cost of fuel in the Eastern plants is somewhere between 30c. and 40c. per ton of copper refined, and, if my memory serves me correctly, in an open-hearth steel furnace it is something like $1.25, so it is evident that steel could be handled to better advantage than copper on the basis of fuel. Now, taking the Great Falls plant to compare with is not quite fair, because that plant operates under peculiar conditions. The furnaces are relatively small; the coal is very bad and is very high in sulphur. No one would think of using a coal with 3.6 per cent. sulphur were anything better available. Due to these conditions, the amount of slag is inordinate, it being quoted as 3.5 per cent., and it is necessary to use lime, as there is a tendency to have troubles from arsenic owing to the very high current density used. I think he has taken about as hard a case as he could pick out. Now as to the conductivity of copper, my own idea about the reason that melted copper does not give as high a conductivity as pieces drawn directly from a cathode, or native copper, is that in the latter case the impurities are present as a mechanical mixture, while after melting they are chemically combined with the copper, which is a very different condition. Further, it is necessary to take the sample from a relatively smooth and consequently pure part of the cathode, as otherwise it would not draw. The same with the mass of copper; you pick out a good solid part of the copper, which is not representative. In fact, the refiners have all found they could not take fair samples of cathodes for a chemical analysis. It is always customary to use wire-bar copper -for the purpose of sampling, and the impurities are several times as great as shown by samples taken from .the cathodes. I think if we examine all of the examples he has given of cases where copper is higher in conductivity, it will fit with that explanation. For example, the Elmore process is a direct electrolytic deposit. Incidentally, at the present time there are a number of ex-

Jan 12, 1914

By Porter W. Shimer

Ox completing the filtration of a solution of pig-iron in hydrochloric acid, and after apparently everything had been transferred to the paper, a minute residue was observed remaining in the angle of the beaker in which the solution had been made. This residue had a steel-gray color and metallic luster and was hard and gritty when touched with a glass rod. Placed under a microscope and magnified 400 diameters, the substance was found to be made up almost entirely of opaque cubical crystals with some fragments having the same color and luster as the cubes. The appearance was strikingly like that of a collection of crystals of iron pyrites. The amount of material obtained from ten to twenty grams of borings by solution in dilute hydrochloric acid, and careful decantation from graphite, was barely sufficient for a microscopic slide. A qualitative test of the minute amount of material obtained in this way, showed the presence of considerable titanium. After many fruitless trials by decantation and other methods, sufficient material for quantitative analysis was finally obtained in the following manner: Two hundred and fifty grams of the coarsest possible borings were dissolved in seven liters of hydrochloric acid of sp. gr. 1.03. A solution by the aid of heat took four to five hours. It was allowed to settle, and the clear solution poured off. Great care was taken that none of the material which had settled to the bottom was lost. The graphitic residue was then completely transferred upon fine bolting-cloth, previously Stretched and fastened over the top of a beaker. All graphitic lumps were broken up by the finger while

Jan 1, 1887

By John J. Childress, Russell L. Cook

Stringent environmental regulations, which have limited the use of sludge ponds, coupled with the economic incentive to clean more coal or to add fine coal cleaning additions to existing preparation plants have increased the use of static thickeners in preparation plants. The Lamella Gravity Settler, sometimes designated Lamella Thickener, is a shallow depth sedimentation device which has been applied in a variety of industrial process and wastewater control projects in place of the conventional raked thickeners. This paper presents the theory and design of the Lamella Thickener, as well as describing the operating results from several full scale installations in a variety of Appalachian preparation plants.

Jan 5, 1978

By Fortunato Pereira Gamba

The Department of Narino (formerly included in the Department of Cauca) is a narrow band about 170 km. (100 miles) wide in the southern part of the Republic of Colombia, near the boundary of Ecuador, as showu in the sketch-map, Fig. 1. Its capital is Pasto, a small city of 25,000 inhabitants; the pri~icipal towns are T?querres, Cumbal, Ypiales, Barbacoas, and Tumaco. The port on the Pacific ocean is Tumaco, and traffic in the interior is carried partly on the Patia river (steam navigation to the fluvial port of Barbacoas), and afterwards overland over poor roads by human bearers or on mule-back.

Jan 1, 1913

By Perry Olcott .

THE Taka oil field is in the northern part of Titus and Franklin Counties, in north- eastern Texas. The small town of Talco, from which the field derives its name, is on the P. & Mt. P. R. R., about 15 mi. north of Mt. Pleasant, the county seat of Titus County. The oil field extends east and west from the town of Talco, the approximate center. In May, 1924, R. L. Cannon, while doing surface geology for the Humble. Oil & Refining Co., mapped the surface trace of this fault structure as evidenced by Upper Midway faulted down against Lower Midway. In the interval of sixteen years between the original surface work and the recent productive well completion, approximately eight wells were drilled into the Woodbine sand without success. The structure was well defined by those tests and all of the wells en-

Jan 1, 1936

By Sidney A. Swensrud

Much has been said and written about uneconomic and evil marketing practices in the oil industry, including such factors as loaning of equipment, price cutting and secret prices, commercial discounts, abuses of credit cards and coupon books, and so forth. It is not my purpose here to add to the discussion of those problems, but rather to attempt a discussion of some of the more basic factors in the general distribution economies of the industry. The economics of distribution in the oil industry cannot be regarded apart from the general economics of the industry as a whole. The attempt to regard them as separate has led many people into the fallacy of believing that the responsibility for the apparent evils in the marketing end of the business lay entirely at the door of the marketing end. Such a view fails to take cognizance of many underlying factors; we can only expect to understand the distribution economics of the industry if we understand its general economics. We must realize also that the oil industry today is essentially the gasoline industry. The oil industry may be said to have begun about 60 years ago. At the outset it was concerned chiefly with the manufacture and sale of kerosene, lubricating oils and greases. Gasoline was then a most obnoxious by-product. The early oil-marketing company was engaged almost exclusively in refining and marketing—it did not concern itself with production but bore the relation to it merely of a purchaser. It may be said that the urge of marketing development in those days, therefore, came from the refining and marketing end of the business. The raw material had not yet begun to exert its enormous pressure, nor had the producer of crude oil acquired a direct interest in the sale of the ultimate finished products. Since then great changes have taken place. With the development of the automobile came a vast new demand for the raw material from which gasoline could be made. No longer could the refining and marketing companies be indifferent to the source of that raw material, particularly in view of the pessimistic outlook then presented as to the probable quantity of oil in existence. And despite the complete overturning of those early estimates, made before the bounty of nature and the skill of

Jan 1, 1931

By E. W. Davis

IF the tonnage of merchantable iron ore remaining in the Lake Superior district is divided by the average of the annual shipments for the past 20 years, it will be found that this ore supply will be exhausted in approximately 35 years. This computed exhaustion period would be an indication of the future activities of the iron-mining industry if it were not for the fact that merchantable ore is being manufactured from low-grade ore, of which there is an almost inexhaustible supply in the Lake Superior district. It is true that at present only the simplest of these low-grade ores are being concentrated to any considerable extent, but progress is being made with the treatment of the more complex ores, and now, in addition to 20 washing plants on the Mesabi Range, three plants are equipped with jigs for the treatment of ore that cannot be concentrated simply by washing. The latest addition to the ore-treating plants of the Mesabi Range is a magnetic roasting and concentration plant at Cooley, Minn., in which ore that cannot be concentrated either by washing or by jigging is roasted to the magnetic state and concentrated on magnetic separators. This plant is beginning its third season of operation, and while it is too soon to make definite predictions, there are strong indica-tions that this new process may make commercially possible the manu-facture of high-grade, merchantable iron ore from large quantities of low-grade ore now considered worthless. After the iron oxide contained in an ore has been converted to mag-netite, almost any desired grade of concentrate can be produced, using magnetic-concentration equipment of the types now in general use for the concentration of the natural magnetites of New York, New Jersey and Pennsylvania. The conversion of hematite (Fe203) to magnetite (Fe304) is easily accomplished by heating the ore to a dull red tempera-ture in a reducing atmosphere. The reaction is slightly endothermic, and while it requires 200 B.t.u. to heat to 900° F. one pound of hematite ore containing 45 per cent Fe, it requires only 100 B.t.u. to convert the oxide into magnetite. In the laboratory, using small quantities of ore, this conversion is very simple, but large furnaces suitable for commercial

Jan 1, 1936

By Louis Cates

AT THE annual meeting of the American Institute of Mining and Metallurgical Engineers in February, 1923, the Chairman of the Committee on Ground Movement and Subsidence appointed a subcommittee to work out a form of questionnaire and to collect data on subsidence and ground movement resulting from underground metal- and coal-mining operations, and on ground movement and safe slopes in connection with open-cut metal-mining operations. The author was requested to take charge of the collection of data and the preparation of a questionnaire in connection with the Committee's studies of open-cut metal-mining operations, this paper is a summary of the work carried on and information received therefrom up to February, 1924. The first approach to the problem of safe slopes is to gather all information that pertains to finished slopes; in other words, the steepest economic angle from the horizontal that will stand in order to uncover the ores to be mined and be safe while the extraction of the ore at the base of these slopes is in progress. Whether or not this angle is 35° or 45° depends on many factors. The number of benches maintained to take care of falling rock and their height and width are direct functions of this overall slope. The slope is here taken to mean the angle from the top edge of the pit through the edges of the respective lower benches to the bottom of the pit. If we accept this definition of the slope, it might save some confusion as there would be a difference if one took the line from the top edge of excavation to the toe of the bottom slope. This latter slope would not be constant, but would vary with the number of benches. The depth of the various ore faces will vary, of course, depending on the deposit; Table 1 shows this to range from 50 ft. to 1100 ft. The geology is an important factor, as are the climatic conditions under which one is operating. A saturated condition in some rock structure causes rock flows; in the Panama Canal excavation, slides have run on a ratio of as low as one on ten, which is a 10 per cent. grade, or a slope of less than 6° with the horizontal. Slopes as steep as 60° have been noted in the Utah Copper operations, so that a wide divergence will possibly be

Jan 8, 1924

By Adrian E. Ross

Diamond drilling through caving formations at depths greater than ZOO0 ft has long presented serious difficulty, generally solved either by casing or cementing. Casing is permitted only when the resulting smaller hole is acceptable, and cementing is frequently a problem at depth. A new method that injects cement under pressure at the desired location is an aid in diamond drilling deep holes. DRILLING through caving formations in diamond drill holes at depths greater than 2000 ft has long been a serious problem. These caving formations are normally passed only by casing the hole or by cementing the hole. Casing the hole is possible only when a resulting smaller hole is acceptable. In as much as only a limited number of reductions are economically practical, cementing is frequently considered the only method suitable for solving these problems. Cementing either by pumping a slurry into the hole or by dropping cylinders containing cement has proved satisfactory on holes under 2000 ft. In holes substantially deeper than 2000 ft these methods are not satisfactory, since during the pump- ing process cement separates out, whereas cylinders usually break before the bottom of the hole is reached. A new procedure, the injector method, apparently solves these problems.* With this method, cement is lowered in the hole in a cylinder, the cement being

Jan 1, 1953

By J. J. Egan

ADVANCES in the production of quality steel have emphasized the need for greater knowledge of the amount and distribution of oxygen in the steel. Control of inclusion content and quality is largely dependent on such knowledge. While many analytical methods have been de-vised for the accomplishment of this end, few are without serious limita-tions in accuracy, convenience, or skill required in application. Usually at least two methods are necessary to determine total oxygen and constituent oxides. Because of the great importance of this problem and the specific interest in the application of such methods of analysis, the various procedures were carefully reviewed at the Union Carbide and Carbon Research Laboratories, with the view of developing a method free from the limitations mentioned above. Intensive experimentation finally led to an improved iodine extraction analysis described by Cunningham and Price. I After this had been thoroughly checked from the standpoint of the analytical chemist, it was rechecked from that of the metallurgist. This involved preparation of a number of small heats of varying composition with determination of total oxygen in the molten metal by the alumina method2 and an analysis of the solidified material without the aluminum addition by means of iodine extraction; the oxides of iron, manganese, silicon and aluminum also being determined by the iodine analysis. The report of this work constitutes the subject of this paper.

Jan 1, 1933

By Adrian E. Ross

Diamond drilling through caving formations at depths greater than ZOO0 ft has long presented serious difficulty, generally solved either by casing or cementing. Casing is permitted only when the resulting smaller hole is acceptable, and cementing is frequently a problem at depth. A new method that injects cement under pressure at the desired location is an aid in diamond drilling deep holes. DRILLING through caving formations in diamond drill holes at depths greater than 2000 ft has long been a serious problem. These caving formations are normally passed only by casing the hole or by cementing the hole. Casing the hole is possible only when a resulting smaller hole is acceptable. In as much as only a limited number of reductions are economically practical, cementing is frequently considered the only method suitable for solving these problems. Cementing either by pumping a slurry into the hole or by dropping cylinders containing cement has proved satisfactory on holes under 2000 ft. In holes substantially deeper than 2000 ft these methods are not satisfactory, since during the pump- ing process cement separates out, whereas cylinders usually break before the bottom of the hole is reached. A new procedure, the injector method, apparently solves these problems.* With this method, cement is lowered in the hole in a cylinder, the cement being

Jan 1, 1953

By William A. Kennedy, Jonathan R. Stahl

This paper deals with the phenomenon of water held in a leach dump due to capillarity. Water is shown to be retained in the fine pores of the ore as well as in the interstices between the rock and soil particles. Upon drainage, Chino leach dump material shows two distinct capillary systems and a double capillary curve is often obtained. Both the igneous and the sedimentary rocks composing the leach material are shown to have appreciable porosity but little permeability. Fluid flow is, therefore, restricted to the interstices between the rock and soil particles. The irreducible water saturation for the aggregate is found to be 884 for the -48 mesh material and 235 for the448 mesh to one inch material. The composite sample of minus one inch dump material had an irreducible water saturation of 52 percent. The irreducible water saturation in the fine pores of the ore was found to be between 73 and 76 percent. Very coarse pores or channels between large rocks exhibit essentially zero capillary retained water. The presence of fine material in a dump can cause high water saturations to be retained and these saturations may be mistaken for perched water tables. Perched water tables can be drained but capillary water will be retained. Capillary pressure data can aid in distinguishing between perched water tables and capillary retained water.

Jan 1, 1974

By K. N. Weaver

In the early 1950's the cement industry began putting a new emphasis on geology. This article points up some of the industry's raw materials problems that geologists are uniquely qualified to handle. Portland cement can be made from relatively abundant industrial minerals and rocks, and this may explain why cement producers placed little emphasis on geology during the early days of the industry. After World War 11, however, the industry began to recognize the need for geological exploration and some of the larger companies began to build a permanent geological staff. This development has its roots in: 1) The rapid expansion of the industry. After World War II and continuing into the early 1950's the demand for cement far exceeded the production capacity. This placed a great deal of pressure on the producers to enlarge capacity at their plants and to develop new sites. 2) The closing of many cement plants due to inadequate raw materials. Producers feared lack of raw materials due to inadequate exploration and evaluation. 3) An ever increasing pressure for upgrading of the quality of portland cement, necessitated upgrading the quality of raw materials. 4) The increasingly large capital investment needed to build new cement plants required a higher degree of accuracy in reserve calculation. These reasons are more or less self explanatory and will not be elaborated on. They are outlined to illustrate the probable evolution of thought among cement management to justify the development of a geological staff. In the author's personal experience the geologist must continually readjust to changing conditions within the industry. For example, cement production capacity grew so rapidly that today production is only about 70% to 75% of rated capacity (73.8% in 1963). Therefore, whereas the geologist's function during the active expansion of capacity was primarily one of exploration, one of his major functions today is the development of existing reserves. This assumes of course that reserves at existing plants have been proven to be adequate in terms of the company's reserve policy. Through the proper development of raw materials, the geologist can markedly influence quality control, production and long range planning. Examples of several of the operations of Medusa Portland Cement Co. will illustrate how proper attention to geologic detail pays off in the above areas. Because limestone is the major raw material of port-land cement, the examples will be concerned with it. DEVELOPMENT OF GEOLOGIC DETAIL One of the prime objectives of an exploration or development project should be the establishment of the stratigraphy and structure of the deposit. The basic tool for exploration and development is still the core drill, and the geologist must gain a maximum amount of information from a minimum amount of drilling. In order to obtain this objective the following is essential: 1) Adequate detailed geologic logging of cores. The core is first logged and separated into lithologically distinct units. In order to make the lithologic breaks as meaningful as possible, representative pieces of core (not all) are etched in dilute HCI. This removes the "drill polish", brings out the structure of the rock and indicates the proportion of dolomite and argillaceous material because dolomite and argillaceous material etch in relief. In this way the lithologic breaks become clearer and one gains a general idea of the chemical makeup before analysis. This method of logging lessens the probability of including two types of stone, e.g. limestone and dolomite into the same sample for chemical analysis. 2) Representative sampling for chemical analysis. After logging, the lithologic units are sampled for chemical analysis. A representative analysis can be obtained by extracting a 1-in. sample for every foot of core. For example, a lithologic interval of 10 ft to 20 ft would yield ten 1-in. samples taken at 11 ft, 12 ft, 13 ft... and 20 ft. These samples are then crushed, pulverized and split into a sample for chemical analysis. This sampling method represents a significant saving of time over splitting the entire core. 3) Preparing the core as a record. Because of the expense of storage and the difficulty of handling large amounts of core, only representative samples of each lithologic unit are saved for reference. An

Jan 1, 1965

By Norman Carmichael

This paper describes the evolution of transportation at an important mining property, beginning at a time when the railhead was 400 mi. distant, and tracing the steps leading to the development of what is probably the heaviest ore train ever operated in underground mine service over narrow-gage tracks, a 300-ton ore train on a 20-in. track, at working costs closely approximating those obtained on systems involving much greater capital expenditure. Useful where geological and financial considerations render inadvisable the excavation and maintenance of large tunnels and heavier rolling stock. THE problem of transportation in the Clifton-Morenci district of Arizona has been one of peculiar difficulty and consequently has been an important factor in the cost of mining and treating the ores produced. From the crude beginning made over 50 years ago, many changes have been necessary to keep pace with the increased output of copper. A heavy-duty haulage system has developed on the original 20-in. track gage to meet the existent metal-mine conditions.

Jan 3, 1924