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By Richard L. Rains

The Bureau of Mines conducted a mineral investigation of the 29,000-acre Dixie Summit area near Elk City, Idaho, during the summer of 1989. At the Petsite mine a marginally economic, identified resource of 4.9 million tons with an average grade of 0.023 ounces gold per ton was delineated. Possible resources of gold, along with silver, copper, lead, and zinc, occur in at least eight other lode deposits. Placer gold may be recoverable by recreational-sized suction dredges in some stream drainages, Five lode mines in the study area have produced over 5,516 ounces of gold (placer gold production was not recorded), 4,757 troy ounces of sliver, 36,746 pounds of lead, and 3,800 pounds of copper. Current mining claims in or adjacent to the study area total 460 lode and 70 placer claims. There are two patented lode claims within the Dixie Summit study area.

Jan 1, 1991

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared fot these tests by high-temperature methods, especially by crystallization from borax melts. FLOTATION test work on Bolivian tin ores some years ago led to the development of several workable schemes of selective soap flotation, but left unanswered many questions of soap-flotation chemistry.' Accordingly, the study of the activation and soap flotation of quartz just reported? was undertaken as a start toward the elucidation of some of the unanswered questions. The experimental work on quartz flotation consisted primarily of small-scale, vacuum-flotation tests in which activator and collector additions and pH were varied between wide limits. In the work to be described in this paper, the soap flotation of cassiterite and fluorite was studied by the vacuum-flotation technique developed in the previous study of quartz. Using oleic acid as collector, conditions for floating cassiterite and fluorite in the absence of modifying agents were first determined. Then the effects of barium, calcium, and alizarin dyes on the flotation of cassiterite, fluorite, and quartz were studied. Alizarin dyes were chosen for study because of the promise they have shown as selective modifying agents in the flotation of non-sulphide minerals.12,1 Also, they form a family of reagents in which there should be a systematic correlation of chemical properties with composition. As a preliminary to the study of cassiterite flotation, an investigation of the preparation of synthetic cassiterite and X ray studies of natural and synthetic cassiterite were undertaken. Experimental Methods The flotation technique and most of the reagent preparations were described fully in the previous paper.' In addition, for the present work it was necessary to prepare satisfactory stocks of clean cassiterite and fluorite and to obtain samples of alizarin dyes. Cassiterite: High-grade cassiterite from the Netherlands East Indies was crushed, sized, and cleaned

Jan 1, 1951

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared fot these tests by high-temperature methods, especially by crystallization from borax melts. FLOTATION test work on Bolivian tin ores some years ago led to the development of several workable schemes of selective soap flotation, but left unanswered many questions of soap-flotation chemistry.' Accordingly, the study of the activation and soap flotation of quartz just reported? was undertaken as a start toward the elucidation of some of the unanswered questions. The experimental work on quartz flotation consisted primarily of small-scale, vacuum-flotation tests in which activator and collector additions and pH were varied between wide limits. In the work to be described in this paper, the soap flotation of cassiterite and fluorite was studied by the vacuum-flotation technique developed in the previous study of quartz. Using oleic acid as collector, conditions for floating cassiterite and fluorite in the absence of modifying agents were first determined. Then the effects of barium, calcium, and alizarin dyes on the flotation of cassiterite, fluorite, and quartz were studied. Alizarin dyes were chosen for study because of the promise they have shown as selective modifying agents in the flotation of non-sulphide minerals.12,1 Also, they form a family of reagents in which there should be a systematic correlation of chemical properties with composition. As a preliminary to the study of cassiterite flotation, an investigation of the preparation of synthetic cassiterite and X ray studies of natural and synthetic cassiterite were undertaken. Experimental Methods The flotation technique and most of the reagent preparations were described fully in the previous paper.' In addition, for the present work it was necessary to prepare satisfactory stocks of clean cassiterite and fluorite and to obtain samples of alizarin dyes. Cassiterite: High-grade cassiterite from the Netherlands East Indies was crushed, sized, and cleaned

Jan 1, 1951

By W. C. Krumbein

Geological problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integrltion of basic sciences with geological principles. Introduction Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the proccssion of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accurnul~ted rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1946

By W. C. Krumbein

Geological problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integrltion of basic sciences with geological principles. Introduction Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the proccssion of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accurnul~ted rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1946

By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles. INTRODUCTION Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the procession of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accumulated rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1941

By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles. INTRODUCTION Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the procession of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accumulated rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1941

By W. C. Krumbein

GEOLOGICAL problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integration of basic sciences with geological principles. INTRODUCTION Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the procession of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accumulated rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology, was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1941

By A. R. Jr. Amos

LOG washers have been used for many years in the washing of clay iron ores, phosphate rock and manganese ores, but not until the past 15 years have they been employed to any extent in the preparation of aggregate materials and fluxing stone. For a machine of such importance where tenacious clay or soft rock must be eliminated, there are few data generally available. The purpose of this paper is to set forth the results obtained from several operations, together with a few suggestions for planning a specific installation. Where the material to be washed out consists of loose surface soil, silt, or small amounts of quickly soluble clay, there is little competition with other forms of washers, because greater power and maintenance are required for the operation of log washers, but where the foreign matter is a stiff clay, such as occurs with high-calcium limestones and in marginal gravel deposits, the ability of other kinds of washers to eliminate com-pletely the hard clay balls is at least uncertain. Then the log washer comes into its own field, for with the breaking and churning action of the logs it will clean out the toughest clay. Even with material from the hydraulic dredge, if it contains tough clay, the log washer is desirable unless the gravel is subjected to a costly soaking and rehandling process. Recently there has been a considerable development in other types of machines to accomplish these results but it is not within the scope of this paper to make comparisons between competitive types, but to present the best obtainable data on log washers only. From the primitive design that gave it its name, a long log hewn from a tree, with paddles forged to shape from strap iron and attached by lag screws, the log washer has gradually been developed to the present all-steel type. As now manufactured, the log washer consists essentially of two built-up logs on which are mounted a series of paddles, carried by shafts fitted at the ends of the logs on bearings fastened outside the enclosing steel box, or trough, which is set at an angle of about 5° to 10° and into which the material is fed. Stuffing boxes at the places where the shafts pass through the box at the lower end are equipped with water-

Jan 1, 1936

By J. W. Downey, A. E. Dwight, M. H. Mueller, H. Knott, R. A. Conner

Sixty new ternary equiatomic compounds are reported with a hexagonal crystal structure that is isostructural with or very similar to Fe2P, D3h-P62m. HoNiAl is a typical example, with a, = 6.9893 ± 0.0003Å, C, = 3.8204 ± 0.003Å, and c/a = 0.54 7. Three holmium atoms occupy (g): x,0,1/2 three aluminum atoms occupy (f): x,0,0; one nickel atom occupies (b): 0,0,1/2; and two nickel atoms occupy (c): 4, + , 0. The nonequivalent 1(b) and 2(c) sites give rise to two sets of unequal interatornic distances (i.e., Ho-Ni and Al-NL in the case above), which account for the prevalence of Fe2P-type tertmry compounds and the scarcity of binary examples. Unit-cell constants are presented for the sixty compounds and density measurements on the compounds HoNiAl and UFeGa confirm that three formula weights are present per unit cell. Neutron and X-ray powder diffraction intensity measurements were made on CeNiAl and HoNiAl, respectively. The atomic posiLiotml parameters in CeNiAl were determined from neutron data to be x = 0.580 5 0.001 for cerium and 0.219 5 0.001 for aluminum. An investigation of the quasibinary section between the binary compounds CeNi2 and CeA12 revealed a new ternary compound CeNiAl. The compound has a hexagonal structure and is isostructural with the prototype compound Fe2P. Additional examples discovered or confirmed in this investigation provide a total of sixty ternary compounds that are isostructural with or closely related to Fe2P. Previous investigators1'2 reported the unit-cell constants for the hexagonal compounds UFeA1, UCoAl, UIrA1, ZrNiAl, ZrNiGa, HfNiAl, and HfNiGa and the present investigation has confirmed that the compounds are isostructural with Fe2P. Independently, Steeb and petzow3 reported the same structure type for UCoAl, UIrA1, and UNiA1. However, the present results suggest a different atomic site occupancy for the component atoms in the three compounds. A detailed investigation of the relative positions of the three kinds of atoms in the compounds CeNiAl and HoNiAl will be discussed. EXPERIMENTAL PROCEDURE The equiatomic alloys were prepared from elements of 99.9+ pct purity by arc melting under a helium-argon atmosphere. After homogenization at temperatures from 700" to 900' C, a metallographic examination was performed by conventional methods, and density measurements were carried out by the immersion method in CCl4. A powder sample was prepared for diffraction studies by crushing a portion of the annealed button. X-ray diffraction patterns were obtained with a Debye-Scherrer camera, in which the annealed powder was glued to a quartz filament, and indexed with the aid of a Bunn chart. Unit-cell constants were calculated from the computer program of Mueller, Heaton, and Miller4 and d spacings were obtained by the program of Mueller, Meyer, and Simonsen.5 The intensity values were calculated from the relation I, ~ (m)(L.P.)F2 by a computer program written by Busing, Martin, and Levy.6 The absorption and temperature correction factors were neglected. An X-ray study of HoNiAl was carried out to take advantage of: large differences in atomic scattering factors for holmium and aluminum, X-ray patters free of background darkening, negligible oxidation at room temperature, and negligible weight loss in the preparation of this alloy. The neutron diffraction studies were made on a powder sample of CeNiAl contained in a -in. diam V tube and a pattern was obtained with neutrons of wavelength The neutron scattering factors employed (x 10-12 cm). In contrast to the scattering amplitude for X-rays, cesium does not have the largest cross section, however, there is a sufficient difference in the neutron scattering amplitudes to distinguish between the atomic species. The neutron transmission was high, 86 pct; therefore, absorption corrections were not necessary for the cylindrical sample. Most reflections could not be observed individually, because of the relatively large unit cell (a = 6.9756 and c = 4.0206Å) and relatively short neutron wavelength; therefore, the intensity of grouped reflections was considered. The Kennicott modification7 of the Busing-Martin-Levy program6 was employed to determine the identity of the atoms at the various lattice sites and the positional parameters. RESULTS A structure for the prototype compound Fe2P was first reported by Hendricks and Kosting;8 however, the structure was in error. The correct structure, as reported by Rundqvist and Jellinek,9 is as follows. The unit-cell constants and volumes per formula weight (V/M) are given in Table I for the sixty compounds examined in this investigation and classified as Fe2P-type compounds. The structure type was determined initially from a comparison of the unit-cell constants of HoNiAl with other known examples of this structure type1' and from the density of HoNiAl, given in Table 11. The density indicated that three formula weights comprised a unit cell, as in the prototype compound Fe2P. The assignment of the three species to lattice sites was made initially on the basis of atomic size. The large holmium atoms were assigned to the 3(g) sites that have a relatively large interatomic distance to nearest neighbor positions, the small nickel

Jan 1, 1969

By Henry Lloyd Smyth

In 1891-92 1 was entrusted with the geological survey of part of the large area lying between the Marquette and Menominee iron-ranges in the Upper Peninsula of Michigan, and extending from the Republic trough on the north, through portions of the valleys of the Michigamme and Fence rivers, to and including the intermediate Felch mountain range on the south. Until a few years back the larger part of this area has been very difficult of access, and much of it is difficult still. The rock-surface is for the most part covered with swamp, forest and glacial deposits of various kinds, and therefore has not invited geological study. For these reasons the district, as a whole, with the exception of the Felch mountain range, remained almost unknown from a geological standpoint until our work in 1892. Our main object was to map the pre-Cambrian rocks, particularly the iron-bearing formations of Algonkian or Huronian age, and to obtain as much information as possible with reference to their sequence and structure, In carrying out this purpose, the use of simple magnetic instruments was found to be of the greatest assistance, and indeed indispensable. In this paper the results of our experience in tracing magnetic rocks by means of the disturbances produced in these instruments, have been brought together in systematic form, with such references to the particular area as are necessary in order to illustrate general principles, with the hope that they will prove useful to other workers in the same region, or in other regions where similar conditions may be encountered. The writer was efficiently aided in the field-work by Messrs. Samuel Sanford and Charlea N. Fairchild for nearly the whole period, and E. B. Mathews and H. F. Phillips for part of it,

Jan 1, 1897

By V. R. Manukonda, I. Iwasaki

Selective flocculation of iron ores is extremely sensitive to the type and amount of soluble salts in pulp solutions. Chemical precipitation of alkaline earth ions combined with ultrasonic treatment deactivates their adverse effects without using any environmentally ill-defined reagents. The manner in which ultrasonic treatment affects starch adsorption on hematite, dissolution of quartz, and the selective flocculation process was investigated. Selective flocculation tests were conducted in the presence of up to 400 ppm calcium ion on a quartz-hematite mixture by precipitation as calcium carbonate, and the role that silicate ion generated by ultrasonic treatment plays in achieving the selectivity of separation is discussed.

Jan 1, 1988

By Paine G. G

The Red Dome Gold/Copper Mine is located approximately 15 km west of the township of Chillagoe which itself is approximately 220 km by road west of Cairns, Far North Queensland. The deposit, with other mines in the Mungana region, was worked from about 1901 to 1927. Exploration by Amoco Minerals Australia in the 1970s and early 1980s outlined a geological resource of 15 million tonnes. A mining reserve of 9.3 million tonnes was identified and originally developed by Elders Resources Limited. The mine commenced operations in March 1986 and was the first large-scale gold project in Australia to be developed solely on the heap leach process. The mine operated successfully as a gold heap leach operation until 1989 when new grinding, flotation and carbon-in-leach plant facilities were installed to process the non heap-leachable component of the orebody including the copper rich -ore. In March 1991, Red Dome Pty Ltd became a wholly owned subsidiary of Niugini Mining Limited. After six years of successful operation and having excavated a 200 in deep pit, it became evident in 1992 that unless more open cut reserves could be identified the operation was limited to six to nine months of high grade ore and a further 15 months of low grade stockpile material. A preliminary feasibility study was carried out to assess the viability of deepening the open cut. This indicated that from a technical and financial point of view it was possible to expand and deepen the open cut. This presented the daunting challenge of developing a 300 in deep, single access, open cut between a high chert ridge, a government railway line and a National Park. The meeting of this challenge is the subject of this paper.

Jan 1, 1994

By Francisco Alberto Marreiros da Rocha Filho

A corrosão é um fenômeno que está intimamente ligado à integridade dos metais e de suas ligas. Esta ocorre de diversas formas, uma das principais é a corrosão localizada na forma de pites, objeto de análise desse estudo, que visa estabelecer um comparativo entre as curvas de polarização cíclica de algumas ligas ferrosas e não ferrosas, ensaiadas em solução de NaCl 0,6 M, mostrando a agressividade que a solução exerce sob cada uma das ligas. Os materiais analisados nesse estudo foram os aços inoxidáveis AISI 304, AISI 444, super duplex ASTM A890/A890 M Grau 6A, o aço carbono AISI 1030, o alumínio comercialmente puro, o cobre eletrolítico e a liga zircaloy- 4. Inicialmente foram medidos os potenciais de corrosão (Ec) de cada liga através do monitoramento do potencial de circuito aberto. Foram realizados os ensaios de polarização potenciodinâmica cíclica em cada liga, comparando o aspecto superficial antes e depois do ensaio através de micrografias óticas, possibilitando que fossem observadas as diferenças entre cada material quanto à resistência à corrosão por pites. Observou-se que algumas ligas não apresentam passivação como o caso do alumínio comercialmente puro, e outras apresentaram regiões passivas e histereses bem definidas, ficando evidente que, dentre as ligas analisadas, o aço inoxidável super duplex ASTM A890/A890 M Grau 6A apresentou os melhores resultados frente aos efeitos agressivos dos íons Cl- presentes na solução, sendo o menos suscetível à corrosão por pites.

Aug 17, 2017

By C. Q. Payne

The art of crushing ores and other materials by means of rolls is a comparatively recent one. While the first record of rolls using iron crushing-surfaces dates hack to the year 1806, when they were employed in Cornwall, their principal developmcnt has taken place during the past 30 years. To Stephen R. Erom belongs the credit of the pioneer in introducing the belted high-speed roll, which has had its origin and a marked development in this country. His notable contrib'ution to the art was in the use of a single bed-plate or frame supporting the roll-shafts, and to which levers holding the mova, ble roll-bearings were pivoted. He also made use of steel tension-rods to support the crushing-strains, and of hammered-steel tires for the crushing-surfaces. These changes brought the design of crushing-rolls to a high level. Following closely thereon, about 1885, W. R. Eckart conceived the idea of the swivel or ball-and-socket support for the roll-shaft bearings. This is an excellent mechanical conception, especially for bearings held against a spring pressure, and while it may not be necessary for all types of rolls, yet it has been quite generally adopted by other roll-designers, and illustrates the refinement which roll-construction has now reached. Other engineers, as, for example, Argall, Vezin, Roger, and Sturtevant, to mention only a few among many, have also given the closest attention to the various details of rolls, such as the frame, springe, bearings, and shafts, and have developed many novel and original designs. It has remained, however, for the boldness and originality of Mr. Edison to extend the field of crushing-rolls in two new directions, and to cause them to ex-

Jan 1, 1913

By Howard J. Smith

For several years this Institute has recorded in its Transactions the various discoveries of potash‡ in America, and the successive stages in the development of an independent domestic potash industry. This paper is intended primarily to continue the record through the year 1935. In retrospect it is not inappropriate to note that public interest aroused in 1910 resulted in the production of some 1090 tons of pure potash in 1915, as a small beginning in the domestic inorganic potash industry, and that the infant industry thus begun reaches its majority this year, following a record production in 1935 of about 600,000 tons of potash salts and exports to no less than 22 foreign countries, including six countries in Europe. This production, with an estimated 200,000 tons of pure potash, may be compared with a production in 1934 of 430,157 tons of salts with an equivalent of 144,342 tons of pure potash. Mine and Plant Improvement During 1935, the American Potash & Chemical Co., at Searles Lake, Calif., began to reap the benefits of its previously enlarged plant facilities, which increased its productive capacity to 180,000 tons of muriate annually. The United States Potash Co., at Carlsbad, N. Mex., improved its operations by installing trolley locomotives and other haulage facilities and is maintaining its development headings two years in advance of operations, with projected plans for orderly mining for years to come. The hoisting shaft at its mine is now equipped to hoist at the rate of 1,000,000 tons annually, and the refinery to produce 150,000 tons of muriate containing less than one per cent of impurities. The Potash Co. of America, at Carlsbad, N. Mex., completed the conversion of its plant from a prospecting to an operating basis late in 1935. The coarse-crushing plant, with a capacity of 150 tons an hour, formerly on the surface, was installed underground, with ore pockets

Jan 1, 1938

By Howard J. Smith

For several years this Institute has recorded in its Transactions the various discoveries of potash‡ in America, and the successive stages in the development of an independent domestic potash industry. This paper is intended primarily to continue the record through the year 1935. In retrospect it is not inappropriate to note that public interest aroused in 1910 resulted in the production of some 1090 tons of pure potash in 1915, as a small beginning in the domestic inorganic potash industry, and that the infant industry thus begun reaches its majority this year, following a record production in 1935 of about 600,000 tons of potash salts and exports to no less than 22 foreign countries, including six countries in Europe. This production, with an estimated 200,000 tons of pure potash, may be compared with a production in 1934 of 430,157 tons of salts with an equivalent of 144,342 tons of pure potash. Mine and Plant Improvement During 1935, the American Potash & Chemical Co., at Searles Lake, Calif., began to reap the benefits of its previously enlarged plant facilities, which increased its productive capacity to 180,000 tons of muriate annually. The United States Potash Co., at Carlsbad, N. Mex., improved its operations by installing trolley locomotives and other haulage facilities and is maintaining its development headings two years in advance of operations, with projected plans for orderly mining for years to come. The hoisting shaft at its mine is now equipped to hoist at the rate of 1,000,000 tons annually, and the refinery to produce 150,000 tons of muriate containing less than one per cent of impurities. The Potash Co. of America, at Carlsbad, N. Mex., completed the conversion of its plant from a prospecting to an operating basis late in 1935. The coarse-crushing plant, with a capacity of 150 tons an hour, formerly on the surface, was installed underground, with ore pockets

Jan 1, 1938

By Roberto Vargas

El Proceso SUTOM efectiviza la precipitación y flotación selectiva del Hg contenido en soluciones cianuradas, generando reducidos volúmenes de espumas con altas concentraciones de Hg, que representan aproximadamente el 5% del volumen de tratamiento, que son fácilmente filtrables con filtros de prensa convencional. La aplicación del proceso es técnica y económicamente factible, logrando extracciones superiores al 98% del Hg, preservando intactos los contenidos de Au y Ag presentes en la solución, obteniendo un precipitado con una ley superior al 39% de Hg

Sep 29, 2023

By Edward Saibel

The various theories that have been advanced to explain or predict the conditions under which a metal fractures may be divided into two categories: First, there are the macroscopic theories generally used in engineering practice. These are empirical in nature and limited in application. For example, the maximum normal stress criterion, which is quite satisfactory for a mild steel in simple tension at atmospheric pressure,' no longer suffices when this steel is pulled under hydrostatic pressure.2 In all of these empirical theories, the critical condition characteristic of the material and of the loading conditions must be obtained experimentally. Secondly, there are the theories based on interatomic forces,3'4 or on the energy required to form new surfaces.5,6 These have all dealt with the theoretical evaluation of the tensile stress necessary to bring about rupture in a purely brittle manner; that is, without plastic flow preceding fracture. All of these attempts have led to values of the tensile strength of crystals or of polycrystalline bodies that are 100 to 1000 times higher than observed values. On this account, it has been thought necessary by some investigators to conceive of a microcrack structure or distribution of flaws throughout the specimen such that the resulting stress concentrations provide the factor necessary to bring about agree- ment between calculation and experiment. It has been pointed out by several observers' that this point of view is highly unrealistic, in that the weakening effect of these flaws or microstructures must be very uniform from specimen to specimen, since the fracture stresses found for various specimens of the same material tested under similar conditions are so nearly constant. Furthermore, since calculations based on atomic forces or atomic energy are for purely brittle fracture, a condition probably never satisfied in tests, agreement is hardly to be expected. Thermodynamic Theory of Fürth In order to resolve this apparent discrepancy between the theoretical cohesive strengths and the observed fracture strengths, Fürth8 advanced a thermodynamic theory of the tensile strength of isotropic bodies based on work of Born relating to the melting of crystals. Assuming an isotropic material free from imperfections and flaws, behaving elastically up to the breaking point, and assuming a connection between rupture and the melting phenomenon, Fürth obtains an expression for the rupture stress a, in the form where Q is the melting energy per unit mass, p is the density, and is Poisson's ratio. Furth compares fracture stresses computed from Eq I with the fracture stresses of metals as given in the Landolt-Bernstein Tables (1927) and in the Hand-

Jan 1, 1947

By Edward Saibel

The various theories that have been advanced to explain or predict the conditions under which a metal fractures may be divided into two categories: First, there are the macroscopic theories generally used in engineering practice. These are empirical in nature and limited in application. For example, the maximum normal stress criterion, which is quite satisfactory for a mild steel in simple tension at atmospheric pressure,' no longer suffices when this steel is pulled under hydrostatic pressure.2 In all of these empirical theories, the critical condition characteristic of the material and of the loading conditions must be obtained experimentally. Secondly, there are the theories based on interatomic forces,3'4 or on the energy required to form new surfaces.5,6 These have all dealt with the theoretical evaluation of the tensile stress necessary to bring about rupture in a purely brittle manner; that is, without plastic flow preceding fracture. All of these attempts have led to values of the tensile strength of crystals or of polycrystalline bodies that are 100 to 1000 times higher than observed values. On this account, it has been thought necessary by some investigators to conceive of a microcrack structure or distribution of flaws throughout the specimen such that the resulting stress concentrations provide the factor necessary to bring about agree- ment between calculation and experiment. It has been pointed out by several observers' that this point of view is highly unrealistic, in that the weakening effect of these flaws or microstructures must be very uniform from specimen to specimen, since the fracture stresses found for various specimens of the same material tested under similar conditions are so nearly constant. Furthermore, since calculations based on atomic forces or atomic energy are for purely brittle fracture, a condition probably never satisfied in tests, agreement is hardly to be expected. Thermodynamic Theory of Fürth In order to resolve this apparent discrepancy between the theoretical cohesive strengths and the observed fracture strengths, Fürth8 advanced a thermodynamic theory of the tensile strength of isotropic bodies based on work of Born relating to the melting of crystals. Assuming an isotropic material free from imperfections and flaws, behaving elastically up to the breaking point, and assuming a connection between rupture and the melting phenomenon, Fürth obtains an expression for the rupture stress a, in the form where Q is the melting energy per unit mass, p is the density, and is Poisson's ratio. Furth compares fracture stresses computed from Eq I with the fracture stresses of metals as given in the Landolt-Bernstein Tables (1927) and in the Hand-

Jan 1, 1947