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By J. S. Marsh

TUESDAY, Feb. 16, was no day for strolling along the cold sidewalks of New York, and a large number of metallurgists sat down with pleasure to the warming task of wiping a few soldered joints. Presented by a joint-wiper of the modern school, G. M. Bouton, of the well-known team of Schumacher, Bouton, and Phipps, the initial paper brought into focus the theme of conservation of strategic metals and described the technique of making the fillet-type joint now employed by the Bell System. Using an over-all average of only 40 per cent of the solder formerly used by the conventional method. this important development bids fair to stick when the war is over. D. L. Martin and E. R. Parker then described the embrittling effect of hydrogen on silver previously heated in oxygen and the less serious but troublesome result obtained under the converse conditions. An interesting example of grain growth restriction created additional material for the lively discussion that ensued among those who have encountered one or another of these phenomena in silver and copper.

Jan 1, 1943

By J. J. Bailey, R. C. Dean

Dr. Maurer has reviewed the large and confused field of rock mechanics and drilling. We have focused our attention on advance drilling and the disengagement of rock. To understand drilling in greater detail is certainly desirable, but such understanding does not necessarily hold any certain promise of near-term practical advancement. In the longer term, it is probably essential. Present work on drilling and our understanding of drilling falls roughly into three separate classes (and, indeed, these are in no way peculiar to drilling): 1) we have knowledge of certain (scientific) topics which seem to be relevant to the process, 2) we have knowledge of the drilling process in both qualitative and quantitative terms from observation of the actual process, and 3) we have certain modeling procedures, by which we bridge the gap between these two previous areas. The usefulness of our scientific knowledge depends critically upon this last item. In all our following remarks we shall consider only those problems of drilling and the disengagement of rock in which the rock behavior is essentially brittle. Let us start by examining some of the problems of constructing an even moderately detailed theoretical model of the drilling process in the small. The prospects of any near-term success in that direction seem extremely meagre; nor is it clear that any great advancement in the practical art of drilling is even likely to result from the construction of such a detailed model. On the other hand, as we shall suggest later, considera-

Jan 1, 1967

By John S. Brown

IN 1925 the writer undertook a detailed statistical study of all producing areas in the Joplin district as a basis for evaluating programs and measuring objectives. For this purpose, the published figures in the yearly volumes of Mineral Resources were used, supplemented for earlier years by publications of the Missouri Geological Survey and other local and less official sources. When all else failed, the available data were projected backward to hazard a reasonable guess as to the unrecorded early output of important areas. Fortunately, the proportion of such prehistory production is not a large factor in any of the totals. These results were used during the next few years to measure the relative importance of various producing areas and to predict the peak period of development of the all-important Picher field. For the purpose of this review, the charts have been completed to the end of 1950. During World War 11, the U. S. Bureau of Mines became interested in a similar study and issued comprehensive statistical tabulations of data up to 1945 ( Info. Circular 7383), which have been checked against the figures used herein. This tabulation, however, does not include all the earlier data used by the writer nor does it offer any estimates of the wholly unrecorded era in the beginnings of the earlier camps. The area covered in this study is shown in Fig. 1 on which are indicated the relative location and approximate outlines of the principal producing camps. This also shows the approximate yield to date of each major camp in terms of combined lead and zinc concentrates. The output of zinc concentrates is roughly seven times that of lead. Hence, the economy of the district has depended primarily on the price of zinc, with lead as an important byproduct. Over much of the productive period, lead concentrates averaged about twice the value of zinc concentrates per ton, and in certain mines or areas the proportion of lead to zinc was substantially above average. The Joplin district is largely flat prairie but is partly moderately dissected, partially wooded land with a relief generally less than 100 ft. The rocks are almost flat-lying, nearly parallel to the surface, and the chief ore formation is the Mississippian Boone limestone, including its cherty phases. This formation either outcrops in the producing areas or is covered by a thin veneer of Pennsylvanian shales. Virtually all the ore occurs within 400 ft of the surface, and a large part at less than 300 ft in depth. Most of the land was divided into small farms or town lots before mineral development; tracts seldom exceeded 160 acres, and averaged considerably less. Mineral rights followed the surface ownership, segregation was rare, and a system of leasing for mineral development became well established early in the region's history, many landowners deriving small to sizable fortunes from royalties. Because of the shal-lowness of the ore and other factors, prospecting and mining was cheaper than in almost any comparable mining district in the United States. This situation, coupled with the widely divided land ownership, offered a fertile field for promoters and speculators and led to the rise of many small mining concerns. Only in its later history, under stern economic compulsion, has control tended to centralize in a few companies. Under these conditions, any important new discovery or successful development had much the effect of a gold rush or an oil boom. Every property in the area was leased quickly, promptly drilled, and, if ore was found, it was soon on the market. Many companies and individuals participated, and the average producing lease-hold probably was about 40 acres in extent. Any important field thus was attacked by anywhere from 10 to 100 or more producers. Production zoomed, eventually steadied or wavered, and ultimately subsided, leaving a desolation of tailings mountains, cave-ins, empty housing, and wreckage. The object of this paper is to depict the pattern of this process, so far as metal production is concerned, and to note the way in which it reacted to economic and political pressures. Production Charts In Fig. 2 is charted the production record, in tons of lead and zinc concentrates combined, of eight of the principal camps, which together account for approximately 99 pct of the total district production, over the years from 1870 to 1950. This period covers all but the very minor beginning of mining history. Two important camps are divided by state lines; hence, it has been necessary to combine production records for the two portions, based on estimates that may be slightly in error. Certain camps are sub-dividable into important units for which separate figures are available in whole or in part and have been charted as fractions of the major unit. The corresponding price of zinc is shown above all the charts. Three camps, Aurora, Neck City, and Galena, show a remarkably symmetrical graphic pattern, which is interpreted as the norm. The curves rise steeply to a peak, level off for an irregular interval, and then drop sharply to zero on a slope corresponding roughly to that covered by the initial rise. The three portions of these charts seem appropriately characterized by the designations of youth, maturity, and decline. On the whole, with some irregularities, the production in each of the three periods seems to be almost equal. A fourth camp, Granby, fails to conform to the normal pattern. It exhibits a very long period of reasonably uniform, stabilized production corresponding to maturity, followed by a rather precipitate decline. Its youth is hidden in the era of prehistory. This habit of steady, long-continued production at an even keel is attributable to the fact that this camp, more than any other, was controlled largely by a single principal owner at any given period over most of its history and this permitted the imposition

Jan 1, 1952

By Frederick T. Fischer

INTRODUCTION Post-Lower Ordovician karstification on a continental scale produced a wide-spread paleoaquifer in the upper portion of the Knox Group of the Southeastern United States. The presence of economic zinc deposits in the Knox of Tennessee is considered to be a con- sequence of this paleoaquifer(1). During The New Jersey Zinc Company's initial exploration of the middle Tennessee region the known artesian nature of modern Knox water and its potentially adverse effect upon mining activities was a matter of concern. This concern intensified as a mining situation appeared imminent and a program of hydrologic investigation was begun in early 1969 and continued through August 1972. The preliminary findings of this work were reported at the AIME World Symposium on Mining and Metallurgy of Lead & Zinc in 1970(2). This paper presents additional data acquired during subsequent stages of the program and relates the hydrologic relationships to the overall geologic framework of the area. PHYSICAL GEOGRAPHY The Elmwood mine is 85km east of Nashville and 8km southeast of Carthage in Smith County, Tennessee (Figure 1). Its physiographic location is in the Central Basin of Tennessee, a basin resulting from erosional breaching across the Nashville Dome of the Mississippian strata which now form the bordering Highland Rims. Both the Central Basin and Highland Rims are divisions of the Interior Low- lands Province. Outcropping rock units of the Central Basin are predominantly Middle Ordovician limestones with scattered high hilltops capped by Devonian and Mississippian strata. One outlier

Jan 1, 1977

By Herbert H. Mellus

TODAY the tractor-drawn carryall scraper has a very important role in the Open Pit div. of Inspiration Consolidated Copper Co. Carryalls have already moved over 3 million tons of material at costs comparable to or lower than for conventional truck and shovel operation, and a major program of scraper stripping and ore production schedules has developed from early isolated scraper applications.

Jan 10, 1953

By Leendert de Witte, Fred J. Radd

In many areas caring failures can be directly related to electrical currents observed in the casings. It is the thesis of this paper that the observed casing currents are mainly due to electrochemical potentials of the type in evidence on spontaneous potential curves of electrical logs. The general nature of these potentials are discussed and an equivalent circuit is given for current and potential distributions around open holes. The casing forms a short circuit to these potentials and tends to average the effects of local cells. The case of casing corrosion opposite the Dakota water sands in the salt-mud area of Kansas is discussed anil used us a qualitative, illustration of the relation between SP's and casing currents. A method of quantitative derivation of casing current distribution frorn electric log SP curves, using linear transform theory, is described and results are compared with a measured current profile. The effects of hydrogen over-potentials at the cathodic portions of the pipe are considered and some laboratory data are given in support of conclusions regarding the over-1.01tuge.s. INTRODUCTION To date an appreciable amount of work has been done on the measurement of oil well casing currents and on the correlation of the anodic portions of the current profiles with corrosive casing failures. Speculations on the origin of the casing currents have, however, remained rather vague; and although almost every plausible cause has been mentioned, there is to the writers' knowledge no clear-cut expose' on the details of the causes of the corrosive currents in the literature. A study of current surveys and casing failures in the N.W. Burnett field, Ellis County. Kan.. indicated the probability that concentration cell emf's between the Wellington salt section and the relatively fresh waters in the Dakota sands were a major cause of the corrosion currents. A more general concept evolved upon analysis of the severe corrosive conditions in the Pleistocene sands in the Ventura Avenue and San Miguelito fields in California. In this area no major variations in the salt content of the formation waters occur and yet large casing currents are observed. An explanation is found in the fact that the local spontaneous potentials which are set up due to concentration contrast between the drilling fluid and the connate water are short circuited when casing is set. The very conductive path through the casing increases the magnitude of the currents and has the tendency to average local sources over fairly large intervals. Current will flow between the sections that are predominently shaly and the sections that are mostly sandy. At the places where the current leaves the pipe, corrosive attack will occur. This same phenomenon will be present wherever unprotected pipe is set through sections that show large SP kicks on the electric logs over reasonably thick interval~. GENERAL- NATURE OF THE SPONTANEOUS POTENTIALS When a sequence of sedimentary rocks is penetrated by a drill hole filled with a mud which has a different salt concentration from that in the formation waters, various types of electrochemical potentials are established between the formations and different parts of the mud column. Opposite clean sand sections. a simple liquid-liquid junction potential will be observed; while opposite argillaccous formations, a membrane potential, often referred to as shale potential, will be established. The first quantitative analysis of these emf's in terms of liquid junction and membrane potentials is due to Wyllie.1

Jan 1, 1956

By A. S. Richardson

Ventilation of the Butte mines has long been a rather difficult problem because of the natural high temperature of the rock. With increase* in mining depth, higher rock temperatures have been encountered, and this has caused a constantly growing demand for more effective ventilation measures. During recent years the hazards of dust in mine air have been more clearly recognized, and have necessitated the adoption of dust-prevention methods. To meet these ventilation problems in the mines of the Anaconda Copper Mining Co., a mines ventilation department was organized in 1918, to act under the direction of the general superintendent of mines. At the present time, under normal operating conditions, the force employed includes the ventilation engineer, two chief assistant ventilation engineers and eight assistant ventilation engineers. The activities of the department are, briefly: (1) planning and supervising operation of the general ventilation system; (2) planning and supervising the operation of dust-prevention measures, together with dust sampling and related microscopic work for the quantitation of the dust samples and determination of particle-size distribution; (3) the design and development of air-conditioning methods to meet present exceptionally severe temperature conditions and in anticipation of future requirements. To a large extent the technical features of the ventilation methods have been described in earlier papers by the author. This paper is written mainly to summarize past accomplishments bearing most closely on health and safety, with a somewhat more detailed account of the dust-prevention measures that have been developed comparatively recently. Facilitating Flow of Am As a basic requirement for the safety of the mcn, all ventilation plans are subject to a ruling that the main operating shafts must be maintained as inlet air courses. Under this condition, a safe, fresh-air escapeway is assured if a fire occurs within the mine, and the shaft; is available as a base

Jan 1, 1940

By A. S. Richardson

Ventilation of the Butte mines has long been a rather difficult problem because of the natural high temperature of the rock. With increase* in mining depth, higher rock temperatures have been encountered, and this has caused a constantly growing demand for more effective ventilation measures. During recent years the hazards of dust in mine air have been more clearly recognized, and have necessitated the adoption of dust-prevention methods. To meet these ventilation problems in the mines of the Anaconda Copper Mining Co., a mines ventilation department was organized in 1918, to act under the direction of the general superintendent of mines. At the present time, under normal operating conditions, the force employed includes the ventilation engineer, two chief assistant ventilation engineers and eight assistant ventilation engineers. The activities of the department are, briefly: (1) planning and supervising operation of the general ventilation system; (2) planning and supervising the operation of dust-prevention measures, together with dust sampling and related microscopic work for the quantitation of the dust samples and determination of particle-size distribution; (3) the design and development of air-conditioning methods to meet present exceptionally severe temperature conditions and in anticipation of future requirements. To a large extent the technical features of the ventilation methods have been described in earlier papers by the author. This paper is written mainly to summarize past accomplishments bearing most closely on health and safety, with a somewhat more detailed account of the dust-prevention measures that have been developed comparatively recently. Facilitating Flow of Am As a basic requirement for the safety of the mcn, all ventilation plans are subject to a ruling that the main operating shafts must be maintained as inlet air courses. Under this condition, a safe, fresh-air escapeway is assured if a fire occurs within the mine, and the shaft; is available as a base

Jan 1, 1940

By Ronald D. Hill, Roger C. Wilmoth

The neutralization of acid mine drainage is becoming a common practice in the eastern United States. Over 200 plants are now in operation. Lime is the neutralizing agent utilized in most treatment plants; however, limestone may have an economic and practical advantage. Current research efforts of the Federal Water Quality Administration, both inhouse and through grants, to develop and demonstrate the use of limestone are reported. In essence, a state-of-the-art review is presented.

Jan 1, 1972

By H. H. Evinger, M. Muskat

A method has been developed whereby one may calculate the productivity factors of producing formations from a knowledge of the reservoir conditions. Account is taken not only of the heterogeneous character of the gas-oil flow system but also of the detailed variations with pressure of the shrinkage and viscosity of the oil, the solubility of the gas in the oil, and even the variability of the gas viscosity and the deviation of the gas from ideal behavior. Curves are shown giving the results of numerical calculations on the production rate as a function of the pressure differential for a high-prcssure and a low-pressure system, three values of gas-oil ratio being treated in each case. Curves are also given showing the variation with distance from the well of the pressure, oil saturation, and permeability. The effect of connate water is briefly discussed in relation to the apparently large discrepancies between the calculated and observed productivity-factor values. Introduction The significance of the productivity factor as a measure of the capacity of an oil-bearing formation to produce is well recognized; for it is the composite and integrated resultant of the physical prop-crties of both the porous medium and the fluid stream passing through it with respect to the ease with which the particular petroleum fluids present in the formation can flow through it and into producing wells. The most direct method of determining the productivity factor of a well consists, as is well known, in the simultaneous measurement of reservoir-pressure differentials and rates of production and the expression of the data in terms of rate of flow per unit pressure drop.' Actual measurements carried out in this manner on producing wells have given factors that generally lie in the range of o to Ioo bbl. per day per pound pressure drop. This wide range arises not only from variations in permeability but also from the varying sand thickness of producing formations. One of the aims of developing a theory of the mechanics of oil production obviously is that of predicting what the productivity factor should be from a knowledge of the individual characteristics of the producing formation and the fluids produced. For homogeneous fluid systems passing through a porous medium into a producing well, it has been known for some time that the steady-state rate of liquid flow Q is given by the formula:* Q ? u log r?/r? where k is the sand permeability, h its thickness, µ the liquid viscosity, ?p the pressure drop between the well and the distant parts of the reservoir, in particular that at a radius re, and r? is the well radius. This gives the productivity factor: f= Q/kh?p ? 2p/µ log re/r? f=Q/ kh?p ? 2p/µ log re/r? which will have a numerical value for a

Jan 1, 1942

By M. Muskat, H. H. Evinger

A method has been developed whereby one may calculate the productivity factors of producing formations from a knowledge of the reservoir conditions. Account is taken not only of the heterogeneous character of the gas-oil flow system but also of the detailed variations with pressure of the shrinkage and viscosity of the oil, the solubility of the gas in the oil, and even the variability of the gas viscosity and the deviation of the gas from ideal behavior. Curves are shown giving the results of numerical calculations on the production rate as a function of the pressure differential for a high-prcssure and a low-pressure system, three values of gas-oil ratio being treated in each case. Curves are also given showing the variation with distance from the well of the pressure, oil saturation, and permeability. The effect of connate water is briefly discussed in relation to the apparently large discrepancies between the calculated and observed productivity-factor values. Introduction The significance of the productivity factor as a measure of the capacity of an oil-bearing formation to produce is well recognized; for it is the composite and integrated resultant of the physical prop-crties of both the porous medium and the fluid stream passing through it with respect to the ease with which the particular petroleum fluids present in the formation can flow through it and into producing wells. The most direct method of determining the productivity factor of a well consists, as is well known, in the simultaneous measurement of reservoir-pressure differentials and rates of production and the expression of the data in terms of rate of flow per unit pressure drop.' Actual measurements carried out in this manner on producing wells have given factors that generally lie in the range of o to Ioo bbl. per day per pound pressure drop. This wide range arises not only from variations in permeability but also from the varying sand thickness of producing formations. One of the aims of developing a theory of the mechanics of oil production obviously is that of predicting what the productivity factor should be from a knowledge of the individual characteristics of the producing formation and the fluids produced. For homogeneous fluid systems passing through a porous medium into a producing well, it has been known for some time that the steady-state rate of liquid flow Q is given by the formula:* Q ? u log r?/r? where k is the sand permeability, h its thickness, µ the liquid viscosity, ?p the pressure drop between the well and the distant parts of the reservoir, in particular that at a radius re, and r? is the well radius. This gives the productivity factor: f= Q/kh?p ? 2p/µ log re/r? f=Q/ kh?p ? 2p/µ log re/r? which will have a numerical value for a

Jan 1, 1942

By Jules E. Jenkins

IN the past quarter century the seismograph has played an increasingly important role in evaluating vibratory effects transmitted to adjacent communities by industrial blasting operations. In this period research has advanced through two major phases—from falling pin seismometers to three-component recording seismographs. The initial phase of this research is now regarded as the era of recording, during which the seismograph merely recorded occasional events. It has emerged from this stage into the era of control and analysis and in this later period has been recognized as a full-fledged industrial tool. Although the falling pin machines of earlier years indicated probable amplitudes of industrial blasting vibrations, they gave no reliable measure of such displacements, nor did they provide essential information concerning direction or frequency of motion. The first contribution of the three-component recording seismograph was the weight-for-distance formula developed by the U. S. Bureau of Mines. This empirical formula enabled users of commercial explosives to determine beforehand the probable vibratory effects of a blast when the weight of the explosives charge and the distance from the shot point were known. This formula has withstood the test of time and is still applicable for blasts detonated by instantaneous methods. The second major contribution of the three-component recording seismograph followed the introduction in 1945 of short period or millisecond delay detonation. This might be described as a two-stage contribution, the first of which revealed a 50 pct reduction in the vibration magnitude when millisecond detonation was used rather than instantaneous discharge. This second part of this double contribution led to the discovery of the vibration dip phenomena, see Fig. 1. In Fig. 1 the horizontal coordinates indicate the displacements amplitude in inches, and the vertical coordinates, the explosive weight in pounds. The top curve is that of the U. S. Bureau of Mines for instantaneous detonation. Its curvature conforms to the two-thirds power of the explosive weight as provided in the weight-for-distance formula; hence the vibratory effects increase in proportion to an increase in the explosive charge. If the other curves shown below are temporarily disregarded, it may be considered that the entire area below this top curve represents both useful and waste energy. As mentioned previously, when millisecond delay detonation was first investigated it was found that in general the U. S. Bureau of Mines curve could be decreased by about 50 pct, or to the position of the middle curve. At the outset it was assumed that this curve would likewise increase in some proportion to the explosive charge, as did the top curve, that is, the curve would indicate a continuous upswing. As seismographic data accumulated this assumption was found to be erroneous in part. It was discovered that

Jan 1, 1957

By J. C. Holm

ALTHOUGH the main constituents of Portland cement are the oxides of calcium, silicon, aluminum, and iron, characteristics of the cement are seriously affected by such contaminants in the raw materials as magnesium, phosphorus, sodium, potassium, sulfur, and others of lesser importance. Sources of cement raw materials comprise a long list of minerals occurring in nature in various degrees of purity. The calcareous raw materials are generally limestone of purity varying from calcite to cement rock (a low-grade limestone of natural, almost correct chemical composition), chalk, marl, seashells, coral, and coral sand. The argillaceous raw materials supplying silicon, aluminum, and iron are mainly various forms of clay and shale, to which may be added silicious sand, iron ore, bauxite, or kaolin for minor adjustment of the chemical composition. The quality of Portland cement in this country, as in most parts of the world, is controlled by rigid specifications limiting both its chemical and physical characteristics, and cement manufacturers must comply with these specifications to market their products. Brandon Raw Materials: An unusual deposit of marl, limestone, and clay occurs 12 miles east of Jackson, Miss., near the village of Brandon. The deposit is of sedimentary origin and of relatively young geological age. Layers of marl vary from putty-like consistency to such hardness that it can be cut with a knife. Interspersed between the layers of marl are bands of limestone varying from very soft to hard. the compressive strength of the hardest layers exceeding 15,000 lb per sq in. The layers of marl range in thickness from a few inches to about 25 ft. The limestone bands seldom exceed 2 to 3 ft but often occur in thinner veins in the quarry face. Above the top layer of the deposit, which may be marl or limestone, a layer of clay ranges in thickness from a few inches to more than 20 ft. Part of this clay is harvested with the raw material to supply part of the argillaceous components, but most of it is stripped as overburden and wasted. A highly silicious clay of extreme fineness, harvested from the bottom of the quarry below the marl and limestone bands, is to correct the silica content. Fig. 1 shows typical examples of the interrelation of the various materials, based on drill logs obtained during exploration of the deposit. The marls vary in moisture content in the bank from 15 to 30 pct and contain up to 70 pct -200 mesh particles and up to 40 pct —10 p particles. A large percentage of the fine fraction is within the colloidal range, making the marl extremely sticky. The limestone beds range in hardness from that of the hardest marl to a medium hard limestone and in moisture content from 2 pct to approximately 14 pct. The line of demarcation is often difficult to draw and the moisture content is possibly the best means of classification. The ratio of soft to hard material is not constant throughout the deposit, but the average is approximately 70 pct soft to 30 pct hard material. Through the years this deposit had been repeatedly explored by cement companies and rejected as unsuitable for cement manufacture, mainly because of physical characteristics. In 1950, after careful exploration of the deposit and comprehensive laboratory and pilot plant tests of the raw materials, officials of Marquette Cement Mfg. Co. of Chicago were convinced that a practical and economical method of processing the raw materials had been devised and authorized construction of a new plant that began production in December 1951. Marl and limestone, common raw materials for Portland cement, usually occur in such a manner that they can be worked separately. Their harvesting and processing normally have presented no difficult problems, as standard equipment and methods are available for handling either sticky or hard materials. No other cement plant utilizes a deposit of the nature of that at Brandon, however, and for this reason no prior art was available for design. When properly blended, the raw materials produced an excellent cement without additives. Basic problems to be solved in designing the cement plant were:

Jan 1, 1957

By William Catron, Cyril U. Colledge

BECAUSE the rich La Colorada orebody of the Cananea Consolidated Copper Co. does not outcrop at surface, after its discovery (by churn drill) and before mining was begun, a large amount of development work was done to learn the shape and extent of the ore and to provide for economic and effective mining. As these openings progressed, the actual shape of the orebody became known and with this knowledge came the realization that mining this rich and unusual deposit without loss of ore or danger to workmen presented several difficult problems. This paper will describe one of these problems; namely, the handling of an inverted cone-shaped core of barren rock, on the periphery of and below which the ore occurred. It was clear that as the ore was mined out from around and under this inverted cone of rock, weighing about 3,000,000 tons, it would hang over the workings, held suspended only by its own tensile strength and threatening to crash into the stopes below with disastrous results to men and mine. The method of mining developed during the years 1928, 1929 and 1930 anticipated and provided for the eventual collapse of this core of rock. In November 1936 the core settled down gradually on the edges of the stopes descending a total of about 50 ft. vertically. The men in the stopes had ample warning and no lives were endangered. There were no air blasts in the mine. The core broke loose from its top support at the 500-ft. level along old fracture planes and evidently is crushed to the ninth level. Movement was of short duration; the following shift went to work in the stopes as usual. No ore was lost. GEOLOGICAL STRUCTURE The shape of the orebody is illustrated in Fig. 1. The geology of the Colorada orebody has been described by V. D. Perry1 and by W. G.

Jan 1, 1938

By K. H. Nimerick, G. P. Laflin

Laboratory data and field tests indicate that substantial losses of valuable coal can be caused by wind erosion. Wind tunnel tests show the effects of wind velocity and particle sizing on the amount of coal lost while in transit. Different coals were evaluated to determine the variables associated with wind erosion. The erosion losses can be substantially reduced by using a binder, or crusting agent, to consolidate the surfaces of the coal into a solid mass which resists erosion. This not only reduces economic loss but minimizes pollution.

Jan 8, 1979

By William C. Grady

Microscopic pyrites are present in all West Virginia coals. Sizes of these pyrites range from 0.1 µ 500 µ (1/2 mm) , and four types are noted: massive, patches, framboids, and isolated crystals. The relative and absolute abundances of the four types vary from seam to seam, and these distributions have a marked effect on the ease with which a seam may be cleaned of pyritic sulfur.

Jan 1, 1978

By I. Iwasaki, R. H. Heerema

The presence of calcium and magnesium ions in iron ore pulps that are upgraded by selective desliming can result in indiscriminate flocculation of both iron oxide and siliceous gangue slimes. The removal of these alkaline earth cations in pulp solutions by chemical precipitation was ineffective as a means of deflocculation of quartz. It was shown by using various techniques (electron micrographs, abstraction, and streaming potential measurements, and cationic flotation tests) that heterocoagulation between the precipitates [Mg(OH)2, hydroxyapatite, and CaCO3] and quartz particles was the reason behind that observation. In addition, the precipitates adversely affected the recovery of quartz by cationic flotation, due to slime coating, a case of heterocoagulation. Magnesium hydroxide produced a uniform layer of coating across the quartz surface, while hydroxyapatite and calcite produced discrete, localized deposits dotting the surface.

Jan 1, 1981

By Alan K. Burton

The individuality of off-highway trucks is largely determined by a number of truck components that include beds, frames, and suspensions. With the exception of tires, these features are generally standard equipment and the mine operator gets "what comes with the truck." With the advent of larger trucks, more complicated haul profiles, and sophisticated production control systems, a new truck support-component industry is rapidly appearing. The impact of the new options for off-highway trucks can be significant in terms of future fleet performance. Innovations include "Mesabi" radiator cores that reportedly offer greater engine temperature control; load indicators that insure proper truck loading at the shovel; and digital communication systems that signal truck status in the haulage cycle. An understanding of tires, brakes, and newly introduced support components is necessary before an optimum choice of truck can be made

Jan 11, 1975

By H. Conrad Meyer

The wizardry of nucleonics has added new and greater dimensions to the almost inseparable "twins"-zirconium and hafnium. So close is their relationship that neither element is found free of the other in any presently known mineral. Although zirconium in the form of its oxide was discovered in 1789 by Klaproth, the metal in an impure, nonductile form was not isolated until 1824 by Berzelius. About 100 years later -1925-van Arkel and deBoer developed and patented a technique for the deposition in vacuo of crystalline, coherent, highly ductile metal of extreme purity on an electrically heated filament through the dissociation of gaseous zirconium tetraiodide. Within the past five years both zirconium and hafnium have been dramatized by the press and in popular science magazines. This has led to the false assumption that practically all of the world consumption of zirconium ores is used in the production of the metals. Recent statistics on the subject show that not over 15 pct of the zirconium ore consumed in 1958 went to ferrosilicon zirconium and zirconium metal. The rest was consumed in refractories, foundry sand and facings and ceramics. The importance of zirconium as a component in compact, relatively lightweight nuclear energy units, such as those now used in the submarine Nautilus,6 is well established. A rival of zirconium metal as a casing for atomic fuels is a newly developed ceramic body. It is claimed to be cheaper than zirconium-to withstand higher temperatures-and to be more resistant to corrosion. Whether such ceramic casings have the required low thermal neutron absorption cross section, high strength and easy formability of zirconium is yet to be demonstrated. Hafnium, because of its low order of abundance and its close chemical relationship to zirconium, was not definitely recognized as a new element until around 1923, despite prior claims. A study of the X-ray spectra of zirconium led to its identification. The circumstances leading to the discovery of hafnium were much less fortuitous than those surrounding zirconium. The more precise tools of arc and X-ray spectrometry lent themselves admirably to the search for elements to fill certain gaps in the periodic table. [ ] Pure, ductile hafnium-a metal similar in appearance to stainless steel-has a specific gravity of 13.3 (zirconium 6.52) and a melting point of 2,200°C. In other respects it closely resembles zirconium except in one important respect which gives it a preeminent position in nuclear energy development, namely, a high thermal-neutron absorption cross section. This explains the necessity of hafnium-free zirconium in atomic piles. The ability of hafnium to capture thermal neutrons makes it an excellent "moderator" of "governor" when used as control rods in nuclear reactors (Table 1).

Jan 1, 1960

By S. A. Swensrud

REPORTS from smelters show that all were so occupied with the in- creased production called for during the first half of the year that little time was devoted to metallurgical developments. Improvements which have been made such as gas-firing and other alterations ill the reconstructed Hayden smelter, will require time for reporting. The labor situation at all plants held the most prominent place and put all other problems in the background. Coming events of considerable importance concerti the construction of two new smelters. The Chino unit of Nevada Consolidated which has long had its concentrate smelted at the El Paso plant of the American Smelting and Refining Co. is constructing its own smelter at the property in New Mexico. The newest Phelps Dodge development of the Clay ore body at Morenci, Ariz., will call for another new smelter.

Jan 1, 1938