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By E. A. Stevens

In a low and gently sloping ridge extending some 1500 ft. southward from Squaw Mt., and now.covered by the buildings, or crossed by the railroads and streets, of a portion of the city of Victor, there is an ancient volcanic vent or crater, which exhibits one of the most interesting phenomena of the great upheaval and volcanic disturbance that built up the hills of the famous Cripple Creek gold-field—of the period when mass was piled on mass to form the mountains and foothills; when fissures and craters opened, and lavas, welling up, overflowed the surface, until, finally cooling, they effectually choked their vents, thus forming many of the ridges that stand out in bold relief, and the dikes that seam the Continent. This particular occurrence, though limited in dimensions, shows in miniature certain stages of the eruptions of Etna and Vesuvius,* Kilauea and Loa; and illustrates what was (with the exception of the penetrating dikes) the closing chapter of the early volcanoes whose emanations have contributed to the

Jan 1, 1901

By Gail Moulton

THE oilfields in Illinois are located principally along the LaSalle anti-cline in the southeastern part of the state. The oil produced comes most largely from beds of Pennsylvanian and Mississippian age, but there is an increasing important production from deeper horizons, as will be noted under new development. The oil is largely of paraffine base, and has an average specific gravity of about 35° Baume. The rank of Illinois as an oil producer has dropped from third since 1913, when its production was exceeded only by that of California and Oklahoma, to eighth in 1923. This has been the result of failure to find new pools of considerable size to offset the declining production of the old wells and of the greatly increased production of some of the other states. The noteworthy features of petroleum production in Illinois during 1924 are: the low rate of decline for the state as a whole; the smaller percentage of dry holes; and the larger average initial yield of the new wells.

Jan 3, 1925

By T. M. Yegulalp

This article summarizes some of the results of the continuing research activity at the Henry Krumb Schools of Mines, Columbia University, directed towards a better understanding of the stochastic behavior of slurry flows in underground coal-slurry pipeline systems. Fundamental ideas supported by field observations are presented and a Semi-Markov model of the slurry flows is developed. As a result of this formulation, behavior of combined slurry flows from N independent coal faces can be expressed in analytical form. The contents of a slurry surge tank receiving slurry flows with certain stochastic characteristics is investigated in a function of discharge pump characteristics and time.

Jan 1, 1983

By S. M. Purdy

Under certain conditions of hot rolling and air cooling from the hot-rolling temperature, bars of a high carbon (0.40 pct C) chrome-nickel austen-itic alloy were found to show magnetism even though no ferrite or martensite could be detected by microscopic or X-yay methods. The appearance of magnetism in such alloys may come from chromium impoverishment of the austenite grains near the precipitated carbide particles. SPORADICALLY, hot-rolled bars of Silchrome 10, an exhaust valve steel, have been found to be magnetic. Because of the analysis of the alloy—0.40 pct C, 18 pct Cr, 8 pct Ni, 3 pct Si —magnetism is unexpected. Preliminary investigation showed neither martensite nor ferrite to be present; only austenite and Cr23C6. Since a literature search was fruitless, a brief study was made of the appearance of magnetism in this alloy. The only basic difference between the two heats is the nitrogen content. Permeability was measured using a Severn magnetic gauge. This instrument consists of a magnet mounted on a counterbalanced arm. A set of calibrated plugs is placed in contact with one pole of the magnet. The specimen is placed close to the other pole of the magnet. If the specimen pulls the magnet away from the plug, it has a permeability greater than that marked on the plug. This technique is swift and reproducible. Previous experience has shown that the permeabilities obtained corresponded to those obtained on a permeater with a field strength of 100 oe. Specimens from both heats were annealed at temperatures between 1700 and 2300°F. One set of specimens was water cooled and another furnace cooled. All the water-quenched specimens were non-magnetic; the furnace cooled ones were magnetic as shown in Table I with no difference being observed between the two heats. Microstructural examination of the specimens showed the expected increase in carbon solubility with increasing temperature. Carbide solution was complete at 2200°F. The specimens heated to 1900°F or below showed some carbide precipitation from the hot-rolled structure. A furnace cooled specimen from a given temperature showed less carbide out of solution than the water-quenched specimen from the next temperature below; e.g., the specimen furnace cooled from 2100°F showed less carbide out of solution than the water-quenched specimen from 2000" F. These studies indicated that the appearance of magnetism was not related to the quantity of carbon in or out of solution and it was related to precipitation at temperatures below 1700" F. A set of samples annealed and water-quenched from 2100° F was aged for 4 hr at temperatures between 1000" and 1600°F; all were non-magnetic. A second set of samples, similarly annealed, was aged 1 to 24 hr at 1200°F with the results shown in Table II. None of the latter set of specimens showed magnetism until they had been aged about 8 hr. Magnetism was quite strong after aging 24 hr. X-ray diffraction studies on several of the magnetic specimens showed that the austenite had a lattice parameter of 3.58A and that the carbide was Cr23C6. Several of these samples were electrolytically digested in 10 pct HCl in ethanol, with a current density of 0.1 amp per sq cm. None of the particles in the residue were magnetic. Accidentally, one cell was run at 1 amp per sq cm; e.g., magnetic particles were found in this residue. After careful separation, the magnetic particles were mounted on a quartz fiber and their diffraction pattern determined using a 5.73-in. Debye-Sherrer camera with CrK radiation. These particles showed a fcc structure with a lattice parameter of 3.57A. Prolonged exposure, up to 16 hr, produced no other lines on the film. The following facts seemed to be established at this time: 1) Austenite was the magnetic phase. 2) Neither ferrite nor martensite could be detected. 3) Magnetization could be produced by aging at 1200°F. One explanation of these data is that the carbide precipitation impoverishes the region immediately around the carbide particle of carbon and chromium and increases the proportion of nickel. All of these serve to increase the Curie temperature of the region around the carbide particle. If the composition change is enough, the Curie temperature will rise above room temperature. If the volume of the affected region is great enough, the magnetism will become detectable. At low aging temperatures, composition changes are great enough but the overall volume of impoverishment is quite small

Jan 1, 1962

By Ed L. Reed

INTRODUCTION The most efficient development of a mine plan for in-situ leach (solution) mining must be based upon an understanding and application of the basic hydrologic characteristics of the aquifer containing the mineral values. Similar knowledge of the overlying and underlying aquifers is also required. This paper summarizes the hydrologic properties of a ground water system and describes some of the more important conclusions that can be drawn from a detailed hydrologic study. Basic to an in-situ leach mining operation is the flow of fluids through porous rock from place to place. The degree to which these movements of fluids can be predicted and controlled determines to a large extent the efficiency of the ore recovery operation. HYDROLOGIC CHARACTERISTICS The principal hydrologic characteristics of a porous medium (sand, intercrystalline or vuggy limestone, fractured basalt, etc.) influencing fluid flow are: Porosity Permeability Thickness Transmissivity Storage Coefficient Water Table or Piezometric Surface Hydraulic Gradient Briefly these parameters can be defined as follows: Porosity: the void space in a unit volume of rock. Permeability: the ease with which fluid will flow through a porous medium. Thickness: the height of the formation which contributes flow to a well. Transmissivity the product of permeability and thickness. Storage Coefficient. the volume of water released from the reservoir per unit drop in head. Water Table or Piezometric Surface: the level at which water will stand in a well: the top of the zone of saturation in a gravity aquifer; the height to which water will rise above the confining bed in an artesian system. Hydraulic Gradient the direction and rate of dip of the water table or piezometric surface. A properly designed pumping test will provide numbers for transmissivity, storage coefficient and the water table or piezometric surface. Drilling records or bore hole logs provide aquifer thickness data from which permeability can be calculated. Ground elevations applied to measured depths to water enable one to calculate the direction and rate of dip of the water table or piezometric surface. Porosity can be determined from core analyses or density logs; it can be estimated from grain size distribution curves in sands or sandstones and from, microscopic examination of drill cuttings derived from carbonate aquifers. CHARACTERISTICS OF FLUID FLOW The characteristics of fluid flow that are vital to an understanding of leach mining include: Velocity Direction Flow Path Radius of Influence The velocity of fluid flow is of paramount importance in planning and managing a leach mine operation. Velocity is directly proportional to the permeability and hydraulic gradient and indirectly proportional to the effective porosity The permeability determined from a pumping test is an average value for the interval stressed; therefore, the velocity calculated from data derived from a pumping test represents average conditions. Under actual conditions discrete portions of the aquifer open to the screen may have permeabilities several times as high as the average and minimum permeabilities only a fraction as much. An injection front will be irregular to the extent that the reservoir rocks are heterogeneous An important consideration is the direct relationship of velocity to head. A reservoir which would provide a velocity of 0.05 feet per day under conditions of equilibrium would allow fluid flow of 36 feet per day under typical leaching operations, i.e. 12-foot injection head, 12-foot pumping level and 50 foot five-spot pattern. The direction of fluid flow is also vital both inside and outside the mine area. In the pattern area the direction of flow is determined by the geometry of the well field and can be approximated by mathematical modeling techniques. Outside the well field, the direction of flow is influenced by both natural conditions and the degree to which production and injection volumes are balanced. Flow directions (and velocities) are critical to an understanding of leachate excursions and their control.

Jan 1, 1979

By Constantine Michalopoulos, Roger C. Van Tassel

Commercial demand for gold in the United States is important. It has a large impact on the total world commercial and overall non-monetary demand. Given the present free market price and our need to import gold, it has a substantial adverse effect upon our international payments position. But, according to most recent estimates, the United States demand is perhaps no more than 20% of the world as a whole. In 1971, United States consumption was estimated at 215.6 tons out of a total of 1,412.1 tons 1. This figure is very close to the 16% figure developed by Consolidated Gold Fields as the average for the years 1968-1970.2 Surveys of both production and use of gold on a world-wide basis are not new. With the bulk of gold production in only a few countries, it has been possible to develop fairly reliable series on gold output. Estimates have been developed on the known reserves of gold and probable output at various prices.3 On the demand side, figures have been somewhat less complete and reliable. The Bank for International Settlements and the Director of the United States Mint have regularly published estimates of commercial use in major industrial countries. The IMF has issued an increasingly comprehensive survey in its Annual Reports. The IMF has attempted to cover all nations-not restricting its efforts to major industrial nations-and has tried to estimate both gold taken for commercial uses (Estimated Industrial and Artistic Use) and for private hoarding. Their method is to begin with data on free world output plus any net sales by the Soviet Union, subtract any additions to world monetary stocks (or add to available supply for any net reductions in world monetary stocks), subtract estimates for commercial demand and have left as a residual an estimate for private hoarding. The method is straightforward and simple but the quality of the data is suspect. Industry sources tend to believe the figures as biased on the low side because of a persistent tendency to underreport gold movements.4

Jan 3, 1974

By I. J. Corrans

Wet high-intensity magnetic separation (WHIMS) has been successfully applied to the recovery of gold and uranium from the residues of Witwatersrand ores. Good overall recoveries have been achieved for particles as small as 12µ, and finer particles of uranium minerals are recovered when present as inclusions. The best results were obtained with a matrix of soft-iron balls 6 mm in diameter. However, pilot-plant tests drew attention to a major defect of the machine: the matrix could be blocked by wood chips and ferromagnetic particles. This problem was overcome by the incorporation of a modification that allows the balls to be discharged from the rotating annulus. Two full-scale units that incorporate the modification have been installed.

Jan 1, 1980

By D. B. McDyre

THE object of this study was to compare variations in slag volumes with tap changes while maintaining all other factors constant. This meant: 1. Same type of heat (Spec. SAE 1030). 2. Same charging material (3500 lb foundry, 4000 lb bought scrap). 3. Same amount of sand by weight to fix slag line. 4. Same method of melting with the exception of tap changes. 5. Same method of weighing slag after each test. The equipment of the Dodge Steel Co. consists of a 132-ton Heroult furnace lined with silica brick, using three 8-in. electrodes and a 2000-kva transformer, with four tap changes. In the melting practice we use a Fischer Carbanalyzer and a Herty viscosimeter and try to standardize all heats by making necessary carbon and slag adjustment before boil to keep all heats as uniform as possible.

Jan 1, 1947

By Tony B. Szwilski

A short study has been made of the underground mining potential in the Plains region, the Province of Alberta, Canada. Particular reference is made to the possible application of longwall mining: Presently underground mining is limited to small scale room-and- pillar methods. The problems anticipated with large scale mining at shallow depths (30 m) are examined. Production factors based upon longwall retreat mining utilizing shield supports are also considered.

Jan 1, 1981

By W. A. Hockings, G. W. Lower, K. A. Smith

The kinetics of dissolution of metallic copper in aqueous cupric ammonium carbonate solutions were investigated. The major variables studied were temperature, agitation, and the cupric, cuprous, ammonia and carbonate concentrations. The rates of copper dissolution from rotating discs were determined by measuring the weight loss. The dissolution rate increased with the square root of the disc rpm and doubled when the temperature was increased from 20°c to 40°C.

Jan 1, 1973

By Peter L. Langsjoen, Kenneth L. Maloney

Ten small and intermediate-sized (4.5 Mg/hr to 113 Mg/hr steam--10,000 to 250,000 lb per hr) coal-fired boilers in the upper Midwest have each been tested on both a bituminous eastern coal and a subbituminous western coal. The purpose of this study was to determine the feasibility of substituting western subbituminous coal for eastern bituminous coal as a means of reducing the SO, emissions from this class of boiler and to demonstrate the feasibility of greatly expanded western coal utilization as a means of reducing the use of oil and gas. The scope of this study was such that the representative boiler types were tested on both eastern and western coal for a period of time sufficient to completely characterize their individual emission and operational characteristics.

Jan 1, 1978

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 M. King Hubbert

DURING the past summer the writer was asked by the Illinois State Geological Survey to make a study of some of its economic geological problems with regard to the applicability of geophysical methods of prospecting to their solution. The following four problems were sug-gested for investigation: (1) the fluorspar area of Southern Illinois, (2) oil structures in the south central part of the state, (3) the lead and zinc-bearing area of northwestern Illinois, and (4) the water supply and gravel deposits of the glacial drift. The prime requirements were to find a means of obtaining a maximum of useful information with a fairly modest outlay of expenditure for technical staff and equipment. The method of procedure adopted was that of making a preliminary study of each of the problems named by means of available office data and published reports with supplementary field reconnaissance where necessary.

Jan 1, 1932

By E. Ryba, D. J. Michel

SAMPLES of REZn2 (RE = rare earth) intermetallic compounds prepared by a variety of techniques have been shown to exhibit an extensively twinned micro-structure.1-4 We have recently conducted compression tests at room temperature on specimens of HoZn2 prepared by a powder metallurgy technique.' The microstructures of specimens before and after testing are shown in Fig. 1. The "before" specimen, Fig. l(a), shows the basic twin structure of this material. Fig. l(b) shows the microstructure of the "after" specimen just below the fracture surface and reveals considerable cross-twinning as well as additional

Jan 1, 1970

By Heinz W. Duddeck, Hans-Konstantin Nipp

The design of storage space or deep mining in rock salt should take into account not only time dependency of the rock salt behavior but also temperature effects. For deep mining of potassium salt the natural increase of temperature with depth may no longer be negligible. For the storage of cryogenic liquid gas in salt caverns more knowledge is nezded about the propagation of deep temperatures and their effects on the stress-strain-creep behavior of the surrounding salt. High temperature problems arise for nuclear waste storages in caverns or drill holes emitting radiation. A numerical model is proposed for the analysis of displacements and stresses including their time and temperature induced change. For the material behavior of salt constitutive equations are chosen composed of a combination of Hooke-Kelvin-Bingham-Newton-model based on experimental results (excluding at present deep cooling), Langer 1980. The parameters involved are depending on the stress level and the temperature. The finite-element-method is applied to rotationally symmetrical three-dimensional problems. The non-linear calculation method is based on an implicit method with respect to time. A modified Newton-Raphson-method and the initial strain approach are employed. Along with some experiences on suitable numerical procedures, examples are shown for the characteristical effects of time-temperature dependency. Having achieved convergency and reliability a method is now available for practical design and parametric sensibility studies.

Jan 1, 1982

By O. P. Arora, I. L. Caplan, H. von E. Doering

ThE interpretation of X-ray and electron diffraction data obtained in plastic deformation studies of hcp a titanium requires knowledge of angular relationships between crystallographic planes and directions. Rarey el 01.' have calculated both interplanar angles and angles between directions for a number of c/a ratios. This information, although useful for approximate applications, does not provide exact data for specific hcp metals. Recently, Hu2 has tabulated interplanar angles specifically for hcp titanium. The present study augments the existing data on titanium by providing the angles between plane normals and rational crystallographic directions in addition to interplanar and interdirectional angles. These angular relationships were calculated on an IBM 360 Computer using a Fortran IV program.* Cal-

Jan 1, 1969

By Wallace Ralston

The East Texas area includes the northeast 38 counties of the state of Texas. It covers all, and extends beyond, the borders of what is commonly described as the East Texas Basin. It is one of the most important oil and gas-producing areas of the Mid-Continent Province. It includes four important oil fields—Van, East Texas, Cayuga and Long Lake— and the recent extension of Rodessa field into Cass County, Texas, may prove to be of major size. Four commercial gas fields are in this area— Bethany, Waskom, Cayuga and Long Lake. Up to January, 1936, all of the oil has been produced from the Upper Cretaceous formations, and most of that from the basal member, the Woodbine sand. Gas is produced from both the Upper and Lower Cretaceous formations. Development in Fields East Texas Field.—This field continued to dominate the drilling and production situation throughout the United States. There were 4036 wells completed in this field during 1935; that is, 365 more wells than were completed during 1934. Drilling activity was due to close spacing of wells and the addition of 10,000 acres to the field. The field is now drilled to a density of one well to 6½ acres, which is certainly more wells than necessary for economic production of the field. The close spacing of wells is due mostly to the type of proration, which is per well allowable based on a potential test, and does not take acreage into consideration, and also to the numerous small acreage tracts such as town lots and excess strips. The field now has 19,519 producing wells. The allowable production for the field during 1935 was 161,118,659 bbl.; estimated production, including illegal or "hot oil," was 174,200,150. The illegal production of oil gradually decreased throughout the year, until an estimated low was reached of 20,500 bbl. daily during the months of November and December. The price of oil remained at $1.00 per barrel throughout the year. As stated, about 10,000 acres were added to the field during the year, making a total of 128,000 productive acres. There is a possibility that

Jan 1, 1936

By Fenton Scott, Patrick Hannon

Some occurrences of lead-zinc mineralization in Mississippian carbonates of central Nova Scotia are briefly described. The results of geophysical and geochemical prospecting are presented. Because the deposits do not give a positive response to these indirect techniques it is necessary to site exploratory drilling through the development of geological concepts.

Jan 1, 1976

By J. Amanat, H. J. Siriwardane

A numerical procedure based on nonlinear finite element analysis has been developed for predicting subsidence profile over longwall mine panels. The developed procedure has been verified by comparing predictions with published field observations at several mine panels. This paper presents certain aspects of predicting subsidence profile over mine panels located in hilly terrain. Analysis of four such cases are presented herein.

Jan 1, 1984

By E. M. Elkin, J. H. Schloen

All known methods of treating and recovering the various components of copper refinery slimes are discussed. The slimes treatment processes presently used by five copper refineries are described and flowsheets are given. A bibliography is appended. THE recent increase in anode copper production at the Noranda smelter placed an additional load on the Montreal East plant of Canadian Copper Refiners Limited. The consequent increase in the amount of anode slimes led to a careful consideration of the various methods of slimes treatment. A critical review of these methods is presented here in the belief that it would be of interest to copper refiners. No such review has yet been published, although a number of individual flowsheets have been described. To make the information of greater value, a questionnaire was sent to all copper refineries. While the overall response to the questionnaire was not entirely satisfactory, the foreign refiners gave much detail in their answers and expressed willingness to cooperate further if needed. Although the data below do not cover all refineries, it is thought that examples of all flowsheets currently in use are included. A comparison of these flowsheets should prove of interest. The paper is divided into two parts. One part deals with a discussion of all known methods of treating and recovering the various components of the slimes. The second describes the processes now in use at various copper refineries for the treatment of raw slimes up to the production of Doré bullion. A brief description of the two main electrolytic methods of parting Doré bullion is appended. Since the first commercial application of electrolytic refining of copper by J. B. Elkington in 1865, the treatment of anode mud or slimes has undergone many changes. The object of treating slimes has always been the recovery and separation of precious metals. With the passage of time, increasing attention has been paid to improvement in recovery and quality of byproducts, mainly selenium and tellurium. The original methods of treatment were crude, although relatively direct. For example," the slimes were fused on a dolomitic clay bed in a reverbera-tory furnace; the slag was removed and the resulting metal cupelled to silver and gold. In another process, the dried slimes were oxidized and scorified on the lead bath of a cupelling furnace. Later, these pyrometallurgical methods were modified by sulphuric acid leaching, followed by fusion with niter in a reverb eratory furnace. A preliminary oxidizing roast improved the leaching step. Straight hydro-metallurgy has not found practical application. No matter what method is employed, the result is Dorb metal—a silver-gold alloy, with or without the metals of the platinum group. Characteristics of the Slimes Anode slimes are made up of those components of the anodes which are not soluble in the electrolyte. They contain varying quantities of copper, silver, gold, sulphur, selenium, tellurium, lead, arsenic, antimony, nickel, iron, silica, etc. The color of raw slimes is grayish black and the particle size is —200 mesh. However, Baraboshkin and Gaev (Ref. 1, p. 37), describe light gray colored slimes from the electrolysis of secondary copper which are composed predominantly of sulphates and of basic salts. In anode furnace practice primary and secondary metals are not usually segregated and such slimes do not commonly occur. Copper in the slimes originates to a large extent in the cuprous oxide of the anodes and is therefore dependent on the oxygen content of the latter: Cu2O + H2SO4 + CuSO4 + H2O + Cu [I] Opinions have been expressed that some of the copper is formed by decomposition of cuprous to cupric sulphate Cu2SO4 ? CuSO4 + Cu PI The product of either reaction is very finely divided. Depending on the slimes composition, much of the copper is combined with sulphur, selenium, tellurium, etc. The balance of the copper is in the free metallic state.

Jan 1, 1951