Search Documents

By William S. Hannan, H. Rush Spedden

FLOTATION may be defined as a process whereby mineral particles are concentrated by selective adhesion to air-liquid interfaces. The process involves attachment of desired mineral particles to air bubbles, and removal of the mineralized air bubbles from the surface of the pulp as a mineral concentrate. PROBLEM Although great strides have been made in understanding the principles of flotation, one part of the process which has not been adequately explained is the mechanism by which selected mineral particles become attached to air bubbles. A glance at the froth of an operating flotation cell demonstrates adequately that use of proper reagents and conditions will result in such attachments; but how such attachment takes place is not definitely known. A better knowledge of this factor might lead to improved flotation practice either through altered machine design or the application of scientific innovations. Direct observation of the behavior of mineral particles and bubbles in an operating cell does not appear promising because of the complexity of the system. For this reason, conclusions concerning the problem must be deduced from theoretical considerations or from observation of simplified systems designed to reproduce conditions thought to exist in an operating cell. PRESENT THEORIES Two mechanisms have been recognized as fundamental in particle-bubble attachment: gas precipitation and direct encounter. It is a simple matter to demonstrate in the laboratory that attachment can be brought about by either mechanism. As to the relative importance of the two in a particular flotation system, however, there is a divergence of views. Taggart1 states, Under exceptional circumstances sufficient force and time to effect attachment may conjoin in an ore pulp undergoing agitation, and a preformed bubble adhere to a collector-coated mineral particle, but the occurrence is rare. . . . Pulp-body froth flotation effects selection in the body of a conditioned pulp by causing gas bubbles to precipitate from solution in the liquid phase preferentially at the surfaces of collector-coated particles, and to cling to these particles. Gaudin2 states that, within the pulp body of an agitation machine, attachment of mineral particles to air bubbles occurs as a consequence of contact between the two. This theory has been supported by theoretical reasoning and much circumstantial evidence. Perhaps the most interesting bit of evidence in favor of this theory is the difficulty in the flotation of fines. If attach-

Jan 1, 1947

By Louis A. Carapella, Ralph Hultgren

When F. Heuslerl found in 1898 that certain alloys containing only copper, manganese, and tin were ferromagnetic, the discovery excited a great deal of interest and led to numerous investigations. It was early found that tin could be replaced by aluminum, arsenic, antimony, bismuth, or boron without destroying the ferromagnetic nature of the alloys.2 Copper may also be replaced by silver.% All these alloys have come to be known as "Heusler alloys." The aluminum alloys apparently were the most magnetic and have been most extensively investigated. However, no agreement has yet been reached as to the source of the ferromagnetism arising from these nonferromagnetic elements. Absence of reliable quantitative data makes speculation hazardous. The value of much of the earlier work was vitiated by lack of necessary precautions against contamination, and by lack of close control of heat-treatment. It was only recently established that in aluminum Heusler alloys4 the ferromagnetism arose from a single phase, an ordered body-centered-cubic structure. With modern methods of preparation, heat-treatment, and X-ray examination, it is possible to prepare these alloys without contamination, to heat-treat them intellgently, and to determine what phase or phases are present in the finished sample. In the present investigation, a series of pure alloys in the comparatively neglected copper-manganese-tin system have been prepared, which consist of a single, body-centered-cubic structure (the beta phase) and whose compositions vary within wide limits. The magnetic saturation values of these single-phase alloys have been quantitatively determined, so that considerable data on the effect of composition on the ferromagnetism have been made available. In the course of the investigation some information on the extent of the stability of the beta phase and the nature of phases in adjacent regions of the ternary diagram has been accumulated. Anomalies in earlier data. have been explained, and alloys have been prepared that are much more strongly magnetic than any previous Heusler alloys. Previous Work In the original work of F. Heuslerl and coworkers,2 a maximum magnetic saturation value of I = 107 was found at the composition Cu6Mn3Sn, while a value for CusMnAl of I = 443 was early measured. Ross and Gray5 found a second maximum at the composition Cu2MnSn, which was much more magnetic than Heusler's original alloy. F. Heusler6 hen reinvesti-gated the system, confirmed their results,

Jan 1, 1942

By William L. Fink, Kent R. Van Horn

Zinc is one of the effective elements introduced to enhance the strength of aluminum. This strengthening is principally attributable to the high solid solubility of zinc in aluminum and the pronounced variation of solubility with temperature. Consequently an accurate determination of the solid solubility curve is desirable. The solid solubility relations have been studied by numerous investigators. Shepherd1 first established the existence of a solid solution region at the aluminum end of the diagram (-v phase) by specific volume and microscopic determinations. Bauer and Voge12 published a constitutional diagram which showed the limits of solid solubility as determined by thermal and microscopic methods. Hanson and Gayler3 presented the aluminum-zinc diagram which is now most generally accepted (Fig. 1). Chill-cast samples were given thermal treatments designed to obtain equilibrium conditions, quenched, and microscopically examined. The solubility was placed between 15 to 20 per cent at 60" C., 20 to 22 per cent at 140" C. and 36 to 38 per cent at 270" C. Sander and Meissner decidedly modified the limits of the -y phase field of Hanson and Gayler's diagram by using similar methods on chill-cast specimens annealed for a shorter period of time. Tanabe,s utilizing dynamic hard-ness, electrical conductivity and dilatometric measurements of specimens at temperature, obtained values comparable to Hanson and Gayler's at room temperature, but appreciably lower at higher temperatures. Nishimura6 concluded from age-hardening results of aluminum-zinc alloy chill castings, which had been quenched from 400" to 500" C., that the solubility of zinc in aluminum at room temperature is less than 5 * Metallurgical Division, Aluminum Research Laboratories. 1 E. S. Shepherd: Aluminum-Zinc Alloys, Jnl, phys. Chem. (1905) 9, 504. 2 0. Bauer and 0. Vogel: Aluminum-Zinc Alloys, Int. Jn1. Melallog. (1916) 8, 101. 3 D. Hanson and M. V. L. Gayler: A Further Study of the Alloys of Aluminum and Zinc. Jnl. Inst. Met. (1922) 27, 267. 4 W. Sander and K. L. Meissner: ZII~ Kenntnis der Konstitution der Aluminium-Zinklegierungen. Ztsch. f. Metallkunde (1922) 14, 385. 4 T. Tanabe: Studies in the Aluminum-Zinc System, Jnl. Inst. Met. (1924) 32, 415 6 H. Nishimura: On the Age-Hardening of Aluminum-Rich Al-Zn Alloys. Mem. Kyoto Imp. Univ. (1924) 3, 133.

Jan 1, 1932

By J. C. Motz

Introduction The variations in crushing plant design seen during the past 30 years provide a valuable source of information and experience from which one can select the optimum arrangement for a specific requirement. The purpose of this paper is to examine some specific equipment configurations as they relate to operating efficiency, plant availability and final product size in the form of mill feed. Due to the varied ore properties, physical space limitations, size of ore body and financial resources, there is no single crushing or grinding flowsheet that is best. Since energy costs have risen dramatically during the recent past, it became obvious that significant savings are possible by selecting equipment and a circuit which offers low power requirements balanced with low wear metal and installed equipment costs. Relatively clear and measurable are the metal and maintenance costs and the ever increasing cost of energy. Metal costs in the form of crusher liners have not quite doubled in the last 20 years, while power costs have increased by a factor of four or five, depending on the region considered. Estimates made only a few years ago on the increased cost of energy are obsolete in view of the recent unstable conditions. Since power is therefore becoming the largest cost area, it behooves us to investigate potential cost saving methods in the form of lowering the KWH/Ton of crude. Crushing To reduce run-of-mine to mill feed requires reduction in a series of stages. The physical size and power requirements of a crusher capable of reducing hard rock vary depending on the application. Extended experience in most crushing plants show that a minus 19MM (3/4 in.) rod mill feed can be and is being produced in three stages of crushing. In the majority of cases, the last crushing stage is closed circuited using anywhere from 19MM (3/4 in.) to 14MM (9/16 in.) slotted openings on the sizing deck. In some copper concentrators, the mill feed is all passing 13MM (1/2 in.) using three stages of crushing and 14MM (9/16 in.) square openings on the closed circuit screens. It was felt by some that crushing to this fine size is only possible if the ore is friable and is relatively soft in comparison to the harder ores. Our results show that some of the copper ores are as hard as taconite and are crush-

Jan 1, 1982

By H. J. Stehli

The first sintering of zinc ores was done at the Bartlesville plant of the National Zinc Co., under the auspices of the late Otto Rissman. Mr. Rissman, who had had a long experience in the treatment of zinc ores, well realized all the difficulties of satisfactorily roasting zinc concentrates, which were becoming finer and dustier as each year went by—thus increasing the difficulties of roasting them in the existing forms of roasters, which were furnaces of the Ropp, Hegeler or similar types. Mr. Rissman's idea of the advantages of sinter was expressed in this way: in a zinc ore dead-roasted in a mechanical furnace there are many particles that are just like an egg; that is, they have a hard and impervious film of fused material on the outside, and in the retorting this completely cuts off access of the reducing gases to the center of the egg until a temperature has been reached at which this shell of the egg can be broken down through fusion. A particle of sintered zinc sulphide, on the contrary, is exactly like a piece of sponge. The moment the retort reaches the temperature at which the reactions can take place, they begin, because the reducing gases have ready access to the interior of the particles by means of the pores of the '" sponge." His faith in the advantages of sinter was amply borne out by the results obtained at the pioneer sintering plant for zinc ores installed by the National Zinc Company. Early Method of Sintering The method of procedure at Bartlesville was to roast the zinc concentrates down to somewhere in the neighborhood of 8 per cent residual sulphide sulphur; to cool these, then to wet them down to the proper moisture and mix them in the mixer of the sintering plant; then to sinter them by means of the heat available from the residual sulphides. The sulphur contents of the roast varied considerably, of course, as it was difficult with the furnaces in use to control the roasting exactly at any point short of dead roast. Hence at times the concentrates were roasted a little too low to sinter readily, and at such times the lack of sulphur was made up by the addition of raw concentrates to the sintering-machine charge in suitable amount.

Jan 1, 1937

By Ernest L. Ohle

IN 1943 diamond drilling from the surface in an area 2 miles southwest of Leadwood, Mo., discovered a lead deposit of a markedly different character from the usual southeast Missouri type. Subsequent drilling of about 500 holes indicated several million tons of ore, and in 1950 a 701-ft vertical shaft was sunk into the orebody. This paper describes the geology, of this interesting occurrence insofar as it is known from the drilling and the small underground exposure at the bottom of the shaft. Geology The location of the Southeast. Missouri Lead Belt and of 'the Hayden Creek property are shown in Fig. 1. As shown here, there are two separate producing areas, one from which the larger tonnage has come, located near Bonne Terre, Flat River, Desloge, and Leadwood, and the other to the south around Fredericktown and including famous old Mine LaMotte. The best published description of Lead Belt geology is by Tarr.* In pre-Cambrian time in this cherty dolomites. Several of these formations may be found in direct contact with the pre-Cambrian as their deposition progressively overlapped the older rocks on the flanks of the igneous knobs and ridges. Immediately overlying the pre-Cambrian there is, not uncommonly, a thin basal conglomerate of granite or porphyry boulders, which is incorporated into the overlying sediments. Deposition of the lower part of the rock section was fairly continuous, and the Lamotte sometimes grades almost imperceptibly into the lower sandy Bonneterre. Since the sediments were deposited on an uneven floor, they tend to reflect the irregularities in that floor. Most of the steep dips found in the district, that is, dips in excess of 10°, are original dips and not caused by deformation. Such domelike structures in the sedimentary rocks around the igneous knobs have localized a considerable number of the orebodies in the district and particularly those in the Fredericktown area. Many of the larger orebodies, however, have no close relation to the pre-Cambrian topography. Most of the lead production has come from the lower 150 ft of the Bonneterre formation, where disseminated ore spreads laterally parallel to the bedding for great distances. Average stoping height is about 20 ft, but in a few places there are stopes over-175 ft high.

Jan 1, 1952

By M. B. Ramachandra Rao

The spontaneous polarization surveys dealt with in this paper were carried out near Guddadarangavvanahalli (lat. 14° 17' N.; long. 76° 24' E.) in Chitaldrug district, which forms part of the Chitaldrug schist belt. The occurrence of gold, copper, lead and antimony ores has been noticed for several years but efforts to exploit them have been unsuccessful, therefore some spontaneous polarization surveys were made in the hope of finding indications of workable ore bodies. The country examined has a rugged topography, with numerous hills on which there is little vegetation. The climate is generally dry, the average annual rainfall of the tract being about 25 in., of which 17 in. occurs during the southwest monsoon. The geological formations of the area pertain to an ancient schistose series known as the Dharwar system (Archean). Locally, the rock formations have been divided into three series1—the chloritic series (or the Chitaldrug formation), the clay series (or the G.R. formation) and the trap series (or the Jogimardi trap). The chloritic series includes a complex of altered ancient traps and volcanic agglomerates intermixed with some schists of sedimentary origin, all of which are highly metamorphosed. The lithological types of this series are mostly distinguishable as greenstone schists, calc-chloritic schists, slaty schists, ochery and calcareous mica-chlorite schists, with subordinate bands of secondary limestone. The clay series (G.R. formation) is made up of shaly and argillistic schists, litho-margic clays, sandstones and brecciated ferruginous quartzites. The Jogimardi trap is mostly of the nature of an epidiorite (hornblende diabase), which is distinctly intrusive in the form of large laccolithic and narrower dikelike masses. In addition to this trap, there are other minor intrusives such as the chalybitic trap, quartz porphyry and quartz reefs. The topographical and geological features of the area are noted on the map of Fig. I. The locations of some of the spontaneous polarization centers determined by the geophysical survey are indicated also. Method of Survey and Apparatus Employed The spontaneous polarization surveys were carried out in the manner recommended by the Imperial Geophysical Experimental Survey.2 Preliminary reconnaissance was first carried out along a series of parallel traverse lines that were laid out over the area. The Potential profiles obtained in these traverses were plotted* on a suitable scale and when any

Jan 1, 1946

By Charles S. Robinson

Abstract-The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains, about 80 km (50 miles) west of Denver. The ore body is being developed for mining by workings that extend more than 1100 m (3500 ft) below the topographic surface. During construction of the mine workings, ground water in fractures in crystalline rocks has been encountered. From 1969 to 1973, Charles S. Robinson B Associates Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic records of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentay rocks and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreases with time. The rate of decrease inflow (or pressure) is exponential. By measuring the change inflow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 8, 1978

By E. O. Bennett

When oil is takcn from a subsurface structure it is generally accompanied by gas. The gas thus produced represents the 1ighter hydrocarbons present in the original petroleurn accurnulation, which arc, insoluble at the reduced pressures created around a well when it is producing. In some cases the gas accompanying the oil may come from a gas-bearing stratum not in immediate contact with the oil. The amount of gas from the formation accompanying each barrel of oil is called the natural gas factor. Energy Causing Well to Flow The force causing the flow of fluid into a well when it is drilled into an oil-bearing structure is the pressure differential between the well bore and the formation. A pressure differential between the formation and the well may be set up in three different ways, as follows: (1) pressure due to gas in solution or in contact with the oil, (2) hydrostatic pressure due to water in contact with the oil (it may be either bottom or edge water); (3) pressure difference due to forcc of gravity. The greatest source of energy for producing oil from most oil fields, and the one over which the greatest control can be exerted, is the poten-tial energy in the gas under pressure in the formation. In any pool there is but a definite amount of gas available. Part of this gas may be in solution and a part in contact with oil. The amount of gas in solution in each bard of oil depends on the pressure and temperature in the formation and the characteristics of the oil. Whether the gas is in solution or in contact with the oil it is necessary to use the energy it, contains as efficiently as possible in order to obtain the greatest ultimate recovery from the pool. Bush1 states: Gas being the most efficient aid in moving the oil, it is important to prevent more of it from escaping than is necessary to remove the maximum amount of oil from the sands. The conservation of this energy is far more important to the producer of oil than his returns from sales of gas to distributing companies. The flowing life of the well is the most profitable period, and keeping the gas-oil ratio low, or keeping the

Jan 1, 1928

By R. O. Harma

Introduction Wet autogenous grinding is utilized in three iron ore concentrating plants operated by the Cleveland-Cliffs Iron Company (CCI). This paper will trace some of the development in converting from the use of metal grinding mill liners to the use of rubber and will update the current performance of rubber liners in these applications. The Cleveland-Cliffs Iron Company is a natural resources firm with major interests in iron ore mining and processing and oil and gas contract drilling. The company also has interests in oil shale, uranium, forest products, and Great Lakes shipping. The three operations discussed in this paper are the Empire and Tilden Mines on the Marquette Iron Range in Michigan's Upper Peninsula and the Sherman Mine in northern Ontario, Canada. The Empire Iron Mining Partnership is managed by The Cleveland-Cliffs Iron Company and is owned by Inland Steel, McLouth Steel, The Cleveland-Cliffs Iron Company, and International Harvester. The Tilden Iron Mining Partnership is also managed by The Cleveland-Cliffs Iron Company and is owned by Algoma Steel Corporation, Ltd., Jones & Laughlin Steel Corporation, The Cleveland-Cliffs Iron Company, Steel Company of Canada, Wheeling-Pittsburgh, and Sharon Steel Corporation. The Sherman Mine is a joint venture managed by Cliffs of Canada, Ltd. and owned by Dominion Foundries and Steel Company, Ltd. and Tetapaga Mining Company, a wholly owned subsidiary of The Cleveland-Cliffs Iron Company. The concentrators at all three mines utilize two stage autogenous grinding. Empire and Sherman process magnetic iron ores (Table 1) and utilize magnetic, hydraulic, and flotation concentration methods. Tilden processes an oxidized iron ore (martite, goethite, and hematite) and utilizes a selective-flocculation desliming and flotation concentration flowsheet. Final grind particle sizes are 90% -325M (43k) at Sherman, 90% -500M (25,u ) at Empire and 85% -500M (25 µ) at Tilden. Developmental History The success of using rubber mill linings in Scandinavia led to the first rubber mill lining used by CCI. It was installed in a conventional primary ball mill at Republic Mine in 1964 as reported by Lindroos (1970). This was followed by additional rubber liners for both primary and regrind ball mills. Generally these rubber linings provided about twice the service life as compared to the Type I Ni-hard liners previously used. Grinding efficiency of rubber was found to

Jan 1, 1982

By R. P. Carreker

ONE of a series, this report is concerned with the experimental documentation of the deformation behavior of pure metals over a wide range of temperature. Previous reports in the series describe the creep behavior of platinum1 and aluminum2 and the tensile behavior of copper,&apos; silver,& and molybdenum.5 Subsequent reports will describe the creep behavior of copper and silver and the tensile behavior of platinum, thus providing extensive creep and tensile data on four face-centered-cubic metals tested under comparable conditions. Material Two lots of high-purity aluminum were used in this investigation. One lot, designated AC, was obtained direct from the Aluminum Co. of America as high-purity aluminum in notch-bar form. A typical analysis of this type of aluminum is 0.006 pct Si, 0.015 pct Cu, 0.006 pct Fe, and 99.975 pct Al. Lot BS was obtained from J. I. Hoffman of the Bureau of Standards as a portion of the Aluminum A described in his report of the redetermination of the atomic weight of aluminum.6 Lot BS originated with the Aluminum Co. of America also, and was received in the standard notch-bar form. A detailed chemical and spectroscopic analysis of lot BS has been published.6 Principa1 impurities were 0.006 pct Si, 0.003 pct Fe, 0.002 pct Cu, and >99.987 pct Al. Samples were processed identically by room-temperature swaging and drawing to 0.030 in. diam wires from approximately ½ in. diam rods that were machined from the notch-bar pigs. Samples were cut from the cold-drawn wire, placed in a grooved graphite block in groups of thirteen, and annealed in air for 1 hr at each of several temperatures, with the results shown in Table I. The two lots of aluminum responded quite differently to annealing, the behavior of aluminum AC suggesting that its grain growth was controlled by impurities. The recrystallization texture of aluminum of similar purity comparably treated has been reported as predominantly <111> fiber with some <100> fiber present.7 Testing Procedure The testing procedure and method of analyzing the data have been described previously.2,3 Annealed specimens of 5 in. gage length were tested in an Instron tensile testing machine at a constant head motion corresponding to a strain rate of 0.04 min-&apos; at a number of temperatures. Instantaneous tenfold rate changes were employed in some tests to deter-

Jan 1, 1958

US 4,141,854-Method of resolving water-in-oil emulsions from the organic solvent extraction of uranium from an aqueous ore leach solution The emulsion is treated at optimum temperature with a water-soluble acrylamide copolymer which contains 5-50% by weight of a lower alkyl substituted tertiary aminoethyl methacrylate or quaternary ammonium salts thereof The emulsion is broken, enabling recovery and reuse of the organic portion of the emulsion A M Pavilcius and M A Latko, assigned to Nalco Chemical Co Feb. 27, 1979 3 pp (252-301 1W) Filed: 12-14-77 (860,542). US 4,142,952-In the recovery of copper from an ore leach solution, the solution is contacted with a water-immiscible organic solvent containing 5 to 20 g/L of o-hydroxyaryloxime and 2 to 20 times the weight of the o-hydroxyaryloxime of nonylphenol The loaded solvent phase is separated from the aqueous phase and stripped with sulfuric acid Copper is recovered rapidly and in high yield from aqueous solutions containing high copper concentrations R F Dalton, as¬signed to Imperial Chemical Industries Ltd Mar 6, 1979 6 pp (204-106) Filed 1-3-77 (756,067). Priority: United King¬dom, 1-30-76 (3788/76), 6-15-76 (24722/76), and 10-21-76 (43711/76). Same- British 1,549,615, dated Aug. 1, 1979 US 4,148,631-In the recovery of nickel and cobalt from a mixed sulfate ore leach solution, both metals are extracted by means of a cationic extractant, the loaded extractant treated with an aqueous chloride or thiocyanate solution to back extract the cobalt, and the cobalt then recovered by solvent extraction or ion exchange with an anionic extractant Recovery is effected in a relatively few extraction steps. F Babjak, V A Ettel, and K. R Dymock, assigned to Interna¬tional Nickel Co , Inc, Apr. 10, 1979 6 pp (75-101 BE) Filed¬7-27-78 (928,401). Priority- Canada, 12-28-77 (293,967) US 4,148,813-An improved extractant for use in the recov¬ery of nickel and cobalt from an ore leach solution comprises a water immiscible organic solvent system containing solubilized mercaptide ions, e g , dodecanethiol. Cobalt and nickel mercaptides solvated in the organic phase are easily stripped in the presence of carbon monoxide and an aqueous alkaline solution A. S. Rappas and J. P. Pemsler, assigned to Ken¬necott Copp

Jan 1, 1980

By M. H. Richman, L. M. Markowitz

MUCH of the available information on which the heat treatments of a particular steel are based is found in the isothermal-transformation diagram. Such is the case despite the fact that the usual thermal treatments involve continuous transformations, i.e., transformations which occur on cooling, rather than isothermal transformations. This rather unusual practice is continued because of the abundance of published isothermal-transformation diagrams1, 2 which are relatively easy to determine experimentally as compared to continuous-transformation diagrams.3, 4 However, this can easily lead to the production of improper micro-structures and may not allow full advantage to be taken of the inherent hardenability of a steel. A mathematical method of estimating the continuous-transformation diagram from the available isothermal data was developed by Grange and Kiefer;5 but, due to the mathematical approximations required in the calculations, the computation of continuous-transformation diagrams has been limited to individual cases and no large-scale compilation of these diagrams is available. With the present availability of high-speed digital computers, the problem of time-consuming approximations may be minimized and continuous-transformation diagrams may be constructed with the insertion of isothermal data into a basic program. It is the purpose of this report to announce the availability of such a program and compare the computed and experimental continuous-transformation diagrams for two different steels. Let us first review the method of Grange and Kiefer5 and then compare the results of the machine calculations with the experimentally determined diagrams. In order to apply this method, one requires the isothermal-transformation diagram and a set of curves representing cooling at constant rates. A section of an isothermal-transformation diagram is shown in Fig. 1 together with a cooling curve of M0F per sec. The cooling curve is constructed to start from the A1 (eutectoid) temperature if the transformation product is the eutectoid microconstituent (i.e., pearlite or bainite), from the A3 temperature if the product is primary ferrite, or from the 4, if it is proeutec-toid cementite. The cooling curve in Fig. 1 intersects the curve representing the start of isothermal transformation at a point A&apos; corresponding to a temperature TX and a time fX. An arbitrary lower temperature To (on the

Jan 1, 1968

By W. H. Triplett

Silver-lead-zinc replacement deposits occur in limestones of the anticlinal Caja range at Providencia, near Avalos, Zacatecas, Mexico. The description deals with intrusives, outcrops, preferred horizons, changes from bedding to fracture, control in depth, and variations in abundance and ratios of minerals throughout a vertical range of 500 m. THE purpose of this paper is to record a few field observations and accumulated office data concerning outcrops, relation of ore occurrences to intrusive and host rock, and mineral zoning. Reasons for some of the phenomena are not clear to the author so the facts are given with the hope that other investigators may be able to furnish the explanations. The Avalos unit of the Compania Minera de Penoles, S. A., operates the Alicante, Bonanza, Providencia, Albarradon, San Eligio, Nazareno, Leona, Salaverna, and Santiago mines situated between Avalos railroad station and Concepcion del Oro on the Coahuila and Zacatecas railroad in the State of Zacatecas, Mexico. Some of these mines are within Penoles property while others are on mining claims leased from the Compania Nazareno y Catasillas, S. A., Mazapil Copper Co., and the American Smelting and Refining Co. The main office and camp are at Providencia, about 170 km southwest of Monterrey, N. L., so the silver-lead-zinc mines of the district are usually referred to as the Providencia mines. The Aranzazu, Catarroyo, and Cabrestante copper-gold mines are situated a few kilometers to the southeast on the same mountain range near Con- cepcion del Oro, the name by which the camp is known. It is operated by the Mazapil Copper Co. The main theme in the following pages is a description of the silver-lead-zinc ore occurrences of the district. Rock Formations Sedimentary Rocks: Many competent geologists have contributed generously to an ample fund of information concerning the sedimentary columns of northern Mexico. Among them are Carlos Burck-hardt, E. Bose, L. B. Kellum, and R. W. Imlay. Carlos Burckhardt, who covered a number of extensive areas in many parts of the Mexican Republic, devoted years to mapping the geology of the Caja, Zuloaga, and Santa Rosa mountain ranges around Mazapil, Concepcion del Oro, and San Pedro de Ocampo, Zacatecas. He did most of the original mapping which has been used as a basis and amplified by others. C. E. Burbridge and, more recently, John

Jan 1, 1953

By A. M. Gaudin

The flotation process has been applied extensively in the mineral and chemical fields. This paper reveals results obtained by an exploration of an application to the biological field. In many ways this study was indeed an exploration since so many factors are different. In the mineral field, the particles, both those floated and those not floated, cover a wide range of sizes and shapes; in the biological field, the particles of one population are primarily of one or two sizes and one or two shapes. This identity in size and in shape gives biological systems the advantage of homogeneity. In the mineral field the particles may be as coarse as a millimeter; in the biological field the size may be a micron, or less. In the mineral field the particles may have a gravity several times that of water so that their apparent gravity is quite substantial. Microorganisms, on the other hand, may have a gravity so near that of the liquor that their settling velocity in the liquor is vanishingly small. These two facts conspire to make bubble-particle encounter in the pulp-body less likely. Finally, microorganisms are living, reproducing, and dying-all of which does not help the experimenter get a balance of materials. The analytical problems, too, are extraordinarily difficult, for the organisms can contain only elements that occur in their environment, although at a different level of concentration. The chemical composition of the surface of microorganisms is readily altered. In spite of these areas of difficulty, microorganisms can be floated to leave practically water-clear tailing, they can be floated from each other and, in fact, the same organism can be fractionated into a float that differs from the sink. SIZES AND SHAPES OF ORGANISMS Most ore pulps are described with reference to the percentage of the pulp that is fine enough to pass a 200-mesh sieve. Thus a copper-ore pulp may be 80% -200 mesh. Since 200 mesh equals 74 µ, a 2000-mesh particle would be 7.4 µ in diameter, and a 20,000-mesh particle would be 0.74 µ. The microorganisms with which this work is concerned are of the order of magnitude of 20,000 mesh. We have worked with Escherichia coli, the colon bacillus, Bacillus cereus, Bacillus subtilis, Bacillus megaterium, and Serratia marcescens. In some pioneer work, Dognonl,2 reported the use

Jan 1, 1962

By W. H. Triplett

Silver-lead-zinc replacement deposits occur in limestones of the anticlinal Caja range at Providencia, near Avalos, Zacatecas, Mexico. The description deals with intrusives, outcrops, preferred horizons, changes from bedding to fracture, control in depth, and variations in abundance and ratios of minerals throughout a vertical range of 500 m. THE purpose of this paper is to record a few field observations and accumulated office data concerning outcrops, relation of ore occurrences to intrusive and host rock, and mineral zoning. Reasons for some of the phenomena are not clear to the author so the facts are given with the hope that other investigators may be able to furnish the explanations. The Avalos unit of the Compania Minera de Penoles, S. A., operates the Alicante, Bonanza, Providencia, Albarradon, San Eligio, Nazareno, Leona, Salaverna, and Santiago mines situated between Avalos railroad station and Concepcion del Oro on the Coahuila and Zacatecas railroad in the State of Zacatecas, Mexico. Some of these mines are within Penoles property while others are on mining claims leased from the Compania Nazareno y Catasillas, S. A., Mazapil Copper Co., and the American Smelting and Refining Co. The main office and camp are at Providencia, about 170 km southwest of Monterrey, N. L., so the silver-lead-zinc mines of the district are usually referred to as the Providencia mines. The Aranzazu, Catarroyo, and Cabrestante copper-gold mines are situated a few kilometers to the southeast on the same mountain range near Con- cepcion del Oro, the name by which the camp is known. It is operated by the Mazapil Copper Co. The main theme in the following pages is a description of the silver-lead-zinc ore occurrences of the district. Rock Formations Sedimentary Rocks: Many competent geologists have contributed generously to an ample fund of information concerning the sedimentary columns of northern Mexico. Among them are Carlos Burck-hardt, E. Bose, L. B. Kellum, and R. W. Imlay. Carlos Burckhardt, who covered a number of extensive areas in many parts of the Mexican Republic, devoted years to mapping the geology of the Caja, Zuloaga, and Santa Rosa mountain ranges around Mazapil, Concepcion del Oro, and San Pedro de Ocampo, Zacatecas. He did most of the original mapping which has been used as a basis and amplified by others. C. E. Burbridge and, more recently, John

Jan 1, 1953

By P. G. Winchell, R. J. Russell

The distribution of displacements of originally plane surfaces by an invariant-plane strain has been analyzed statistically. The displacement ratio (the magnitude of the displacement of a point originally a unit distance from the invariant plane) can be determined from an analysis either of tilts of random surfaces or of displacements of random scratches scribed on a randowz surface. In either case the mean of the tangent of the observed displacement angle is related to the displacement ratio, and the number of observations used in determining the mean is related to the confidence limits placed on the estimate of the displacement ratio. In estimating the effect of applied stress on a phase transformation whose displacement effects can be approximated as an invariant-plane strain,* the dis- placement ratio of the invariant-plane strain is of primary importance. Two procedures for determining such displacement ratios are considered here. In the tilt method the measured quantity is taken to be the angle through which a random polish plane is rotated by the invariant-plane strain. In the scratch method the measured quantity is taken to be the angle between the original direction of a random scratch in a random polish plane and the projection of its final direction in the polish plane. In order to obtain precise results from either of the methods, it is necessary to measure the relative volume change associated with the strain in a separate experiment. TILT METHOD A locally homogeneous invariant-plane strain, P, with displacement ratio, S, may be written&apos; where ; and < are unit vectors indicating the displacement direction and invariant-plane normal, respectively, as pictured in Fig. 1. Eq. [I] describes a uniaxial strain if the direction of displacement is parallel to the invariant-plane normal and a pure shear strain if the displacement direction is perpendicular to the invariant-plane normal. The original orientation of the random polish plane relative to the invariant plane and to the displacement direction is shown in Fig. 2. The angle 03 between < and u is related to the relative volume change, ?V/V, and to the displacement ratio by As a result of the invariant-plane strain, the polish plane is rotated about its intersection with the invariant plane by the angle y, which is always taken to be positive. The tangent of this angle in terms of the above parameters is

Jan 1, 1967

By Charles S. Robinson

The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains, about 80 km (50 miles) west of Denver. The ore body is being developed for mining by workings that extend more than 1100 m (3500 ft) below the topographic surface. During construction of the mine workings, ground water in fractures in cystalline rock has been encountered. From 1969 to 1973, Charles S. Robinson & Associates, Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic record( of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentary rock and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past. Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreases with time. The rate of decrease in flow (or pressure) is exponential. By measuring the change in flow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 1, 1979

By A. Sutulov

The segregation process, an alternative to benefi-ciation of oxidized and mixed sulfide-oxide copper ores, is studied here with particular emphasis placed on time, temperature, and coke and salt percentage factors. The results show that in a segregated charge, the copper assay of the coarsest fractions normally is of the same order as the copper assay of the tails obtained from grinding and flotation of the same charge. This observation suggests the possibility of limiting or even eliminating the grinding step from the flowsheet of a segregation plant. The segregation process, which offers an alternative to beneficiation of oxidized and mixed sulfide-oxide copper ores, was discovered in 1923 by Moulden and Taplin1,2 who were attempting to apply the Perkins process3&apos;4 to a Chilean ore from the Sagasca mine. After a number of investigations and pilot plant tests,&apos;-&apos; the segregation process became a successful industrial operation.&apos;r9 The process aroused considerable interest in Chile because of the existance of large reserves of oxidized copper minerals which could not be treated by conventional hydrometallurgical methods because of the high consumption and prohibitive cost of sulfuric acid. During the last two years, the Mineral Dressing Dept. of the Institute de Investigaciones Tecnology cas of University of concepci6n (Chile) has carried out a test program on 23 different ore samples representative of the national territory. These tests were carried out on a semi-continuous and batch scale with a rotary, automatically controlled and gas-fired furnace (supplied by Bartlett and Snow, Fig. 1). The results of these tests indicate that out of the 23 samples 20 can be successfully treated by this process with recoveries of copper ranging from 85 to 95%.10,11 The purpose of this paper is to treat some specific problems related to the segregation process. TIME AND TEMPERATURE FACTORS Time and temperature of calcination play an important role in the segregation process. When moderate salt and coke conditions were maintained (each of reagents was added in the quantity of 1 — % wt), systematic testing easily demonstrated the influence of these two factors on segregation and flotation recovery. The pertinent results are summarized in Fig. 2. To determine what specific changes the segregation process made on the ore, the samples, segregated at 700°C for different periods of time and under standard conditions, were granulometrically analysed and

Jan 1, 1963

By C. M. Schwartz, J. R. Bridge, D. A. Vaughan

THERMAL expansion coefficients of a uranium were originally reported&apos; on the basis of X-ray diffraction measurement of lattice constants at 25°, 300°, and 650°C. These data have been reproduced by Katz and Rabinowitch.&apos; CuK radiation had been used in this work, with consequent crowding of the patterns. Considerable overlap of the back-reflection lines was observed as the temperature was raised. Subsequent reexamination of the data led to the conclusion that errors had resulted from failure to obtain unequivocal indexing of the high angle reflections at elevated temperatures. The measurements have been repeated, using FeK radiation, which provided sufficient dispersion to assure proper indexing of the reflections, at each temperature level. The unit cell dimensions were re-determined at ten temperatures, from 25" to 650°C. Schuch and Laquer easured the macroscopic contraction from room temperature down to —253°C, and reported a negative value from —210" to —253°C; they suggested the possibility of the occurrence of a phase change. In the present work, the lattice constants of uranium have been measured down to —253°C, to test this hypothesis. Filings were prepared from a single piece of pure uranium bar stock. They were carefully cleaned with a magnet and pickled in nitric acid to remove traces of iron from the file. They were then annealed at 600°C in a sealed evacuated silica tube. The annealed filings were pickled in strong nitric acid to remove any oxide layer, washed in water and alcohol, quickly dried, and sealed in evacuated thin-walled silica capillary tubes. If properly sealed, the sample could be heated to the a-ß transforination temperature without significant buildup of the diffraction pattern of oxide. The high temperature X-ray diffraction camera was modified from the design of Hume-Rothery and Reynolds.&apos; The thermocouple used to record the specimen temperature was calibrated from lattice-constant measurements of a standard silver specimen, using the Hume-Rothery and Reynolds values for silver over the temperature range from 25" to 700°C. Temperatures were reproducible to 210°C. Temperatures to —210°C were attained by passing precooled gas over the sample. The gas from the cooling train was directed over the sample capillary tube and thermocouple by means of a chimney of 1-mil polystyrene. The 36-gage Cu-constantan thermocouple had been calibrated by

Jan 1, 1957