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By T. Matthews

"One critical factor in mineral reserves reporting, as well as mine-reserves reconciliation, is the impact of dilution and ore loss in the mining process. This paper considers the implications of various factors on dilution and ore loss projections, by orebody geometry, mining method, and ore control systems. We also discuss the implications of resource estimation methodology on dilution for reserves. DEFINITIONS Dilution and ore loss are two critical concepts in mining, which address the differences encountered between modeled grade and tonnages and actual production. Dilution is volume increase and grade reduction caused by multiple factors, chief among which are mining of waste material along ore-waste contacts, mining of internal waste as ore, and misclassification of waste as ore in the ore control process. There are also geostatistical and estimation aspects sometimes lumped with dilution, including the volume-variance effect (the tendency for small volumes of material to include a less regular distribution of grade than large volumes of material). Ore loss is described as reductions of ore volumes in the mining process due to misclassification of ore as waste in the ore control process, exclusion of discontinuous mineralization from mining due to geometry or continuity, and mechanical losses in the mining process. Dilution is typically taken as an increase in tonnes of ore with no change in contained metal (and thus results in a reduction in grade.) (Some workers consider the likely grade of the diluting material as well, particularly in deposits with gradational grade boundaries—this will be addressed later in the text.) Ore loss is typically taken as a reduction in tonnes at average grade of the ore, and thus results in a reduction in both tonnes and contained metal. If model (resource) tonnes are Mt, grade is Mg, and contained metal is Mm, the resource with ore loss (L) and dilution (D) included (Rt, Rg, and Rm) will be:"

Jan 1, 2015

By E. N. Silverman

Mixtures of' MnS, ZFeO-SiO,, ZMnO.SiO, FeO, and MnO were prepared synthetically and used to study the planes ZFeO. Si0,-ZMnO.SiO,-MnS, FeO-MnO-MnS, and Fe0-MnO.Si0,-MnS in the quaternary system. Because the oxides and silicates studied flux MnS, inclusions in this system are partly liquid during rolling. Also, oxygen can modify subsurface inclusions through the reaction MnS + FeO—FeS + MnO during the soaking of ingots and the reheating of blooms and billets. NONMETALLIC inclusions in steel have long been a subject of study and conjecture because the properties of many steels are known to be affected by the the kind and amount of inclusions present. In free-machining steels, the type of inclusion present has a direct bearing on their machinability; in other steels, cleanliness is important and metallurgists direct their efforts at reducing the amount of non-metallic inclusions. Thus, the accumulation of knowledge about the formation and behavior of inclusions during all stages of steelmaking and processing should aid in improving the quality of steels and decreasing the production costs resulting from rejections. Previous studies of inclusions have contributed greatly to our understanding. The investigators have generally examined inclusions in finished steel. Boulger, Moorehead, and Garvey1 found that in Bessemer steels, low silicon contents results in globular sulfide inclusions with attendant high machin- ability ratings. Van vlack2 also found that low silicon contents favor inclusion morphology that contributes to high machinability ratings. Boquist and Stoll* found that silicon content affected sulfide inclusions and machinability of blooms, billets and bars more than did the finishing temperature in the range between 1775° and 2075°F. Carney and Rudolphy3 studied the distribution of sulfur, manganese, silicon, and carbon in a commercial ingot of resulfur-ized steel and found that silicon was concentrated near the bottom. This helped to explain why bottom cuts had poorer machinability. Klinger and Koch4 developed techniques for extracting inclusions from steel, and the technique devised by Gurry, Chris-takos, and stricker5 for extracting carbides can also be adapted to the study of inclusions. A different approach to the study of inclusions in steel consists of synthesizing the constituents that form inclusions and determining the phase eauilibria in the system that contains the constituents. The resulting phase diagrams can then be used to determine the effect of the various constituents upon each other. In this way, it becomes possible to under-

Jan 1, 1962

By Robert F. Droullard

The U. S. Bureau of Mines (USBM) has investigated instrumentation and methods for measuring exposure to radon daughters in underground mine atmospheres. Both personal and area monitors have been studied through in-house and contract research. A field study in uranium mines identified some reliability problems that required additional work for the personal dosimeter systems. Improved versions of continuous working level detectors have been developed and tested for use as area monitors in underground mines. Test results for the personal and area monitors were satisfactory for underground mine applications.

Jan 1, 1981

By D. C. Cupertino

Oxime based solvent extraction provides the user with a selective concentration process for copper prior to electrowinning. The selectivity required is largely for copper(II) over iron(III) and this is achieved by the preferential formation of the square planar copper-oxime complex in the organic phase. The copper/iron selectivity of oximes can however, be altered by modifiers or other types of oximes and may be enhanced in the presence of certain esters. Whilst the oxime based SX processes is important for operations leaching copper from laterite ores, the high selectivity will also be significant in processing streams arising from other leaching regimes which are currently under development, for example leaching of sulfide mineral ores. This paper presents some initial results using Molecular Modelling techniques to further our understanding of the nature of the copper/iron-oxime complexation processes together with some plant studies undertaken at a number of different mine sites investigating selectivity, and other properties, for some modified reagents. Some studies of the interfacial properties of the these systems are reported to explain in part the practical observations.

Jan 1, 1999

By A. E. Outerbridge

It has been generally accepted as a fact that cast-iron, under the influence of repeated shocks, becomes brittle, and will finally break under a blow which otherwise it would have withstood. It will probably surprise metallurgists, therefore, to learn that experiment disproves the supposed fact, and establishes exactly its opposite. The result of about a thousand tests of bars of cast-iron of all grades, from the softest foundry-mixtures to the strongest car-wheel metal, enables me to assert with confidence that, within limits, cast-iron is materially strengthened by subjection to repeated shocks or blows. It is very well known that the usual process of annealing castings—such, for example, as car-wheels—increases their strength by relieving cooling-strains. But it is not well known (if known at all prior to this announcement) that the molecules of cast-iron are capable of movement—for they do not touch each other*—without the necessity of heating the casting, and that they can thus rearrange themselves in comfortable relation to their neighbors, and relieve the overcrowding near the surface of the casting. In more technical words, a molecular annealing may be accomplished at ordinary temperatures which will release the strains in the castings, precisely as does annealing by slow cooling in heated pits or ovens. A statement so surprising should not be made without sufficient data to establish its correctness beyond cavil, since it is contrary to former

Jan 1, 1897

By Harold C. Pierce

"INTRODUCTION During the years 1941 to 1945, the United States produced less than one-half of one percent of all primary nickel, whereas the nation's consumption of the metal amounted to nearly three-fourths of the world's supply. Although postwar nickel consumption probably will be less than wartime consumption, trade- estimates for the next 10 years are well above the average established during the 1930-1940 decade. The greatest consumption is expected in nickel alloys, particularly nickel-alloy steels. 3/ The greater use of nickel cast irons and nickel-clad metals also signifies an expanding nickel market. In anticipation of the postwar demand for nickel, and realizing the seriousness of the ""have not"" position of the United States with respect to this metal, the Bureau of Mines, sent an engineer 4/ into the lower Copper River region of Alaska during the summer of 1944 to investigate the nickel deposits near the head of Canyon Creek. Samples from the Spirit Mountain nickel prospect were sufficiently encouraging to justify more intensive exploration. As a result, a program of surface trenching, systematic sampling, and detailed mapping of the property was adopted and directed by a Bureau of Mines engineer 5/ in the summer of 1945."

Aug 1, 1946

By Richard Maurice

RÉSUMÉ La restauration du site minier Poirier, à Joutel s?est déroulée entre 1998 et 2001. Le principal élément des travaux a été la restauration du parc à résidus et des zones d?épanchement qui totalisaient 4,5 millions tonnes de résidus répartis sur une superficie de 74 hectares. Les résidus sont fortement générateurs de drainage minier acide. La première partie de la présentation consiste en un bref rappel du concept de restauration suivi d?une description des principaux éléments de travaux avec l?emphase sur les leçons apprises de l?exécution des travaux. La deuxième partie de la présentation est axée sur les résultats du programme de suivi en cours depuis la fin des travaux en 2001. Les éléments de suivi se rapportent à la baisse du niveau de la nappe phréatique à l?intérieur de la cellule, au tassement des résidus dans la cellule, aux mesures de température et d?oxygène à l?intérieur de la cellule et finalement à l?amélioration dans la qualité de l?eau de surface. ABSTRACT The reclamation of Poirier Mine, in Joutel, was carried out between 1998 and 2001. The main component of the works has been the reclamation of the tailings basin and tailings spill area which contained a total of 4,5 million tonnes of tailings and occupied some 74 hectares of ground surface. The mine tailings are highly acid-generating. The first part of the presentation will deal with a brief review of the reclamation plan followed by a short description of the main work components laying emphasis on experience gained during construction. The second part of the presentation will deal with the results obtained from the environmental monitoring program still in progress since the end of reclamation work in 2001. The aspects discussed include the drawdown of pore water inside the covered tailing pile, the settlement of mine waste material, the monitoring of moisture, temperature and oxygen underneath the liner and finally, the reduction of loadings in surface water.

Nov 1, 2002

By A. R. Troiano, E. A. Steigerwald, F. W. Schaller

D. N. Williams(BatteZle Memorial Institute)-The authors have presented an extensive collection of arguments pertaining to the role of stress in hydrogen embrittlement. The basic assumption of these arguments is that stress is essential as a driving force for diffusion of hydrogen. However, in view of the rapid diffusion rate of hydrogen in steel at low temperatures as evidenced by the ability to alloy with hydrogen by electrolytic charging, it seems unlikely to me that stress acts in this manner. Instead, I would like to suggest that stress may be essential for the nucleation of hydrogen in steel. I believe that such an assumption would equally well satisfy the experimental data presented by the authors. I should also like to comment on the interpretation of the data presented in Figs. 5 and 6. Fig. 5 shows the effect of hydrogen content on ductility in a rupture test. The curve as drawn by the authors indicates an abrupt transition from ductile to brittle behavior at about 0.001 amp per sq in. (5 ppm). The data points would equally well support a gradual transition from ductile to brittle behavior extending over the range from 0.0008 to 0.02 amp per sq in. (4 to 8 ppm). A gradual transition would be the ex-

Jan 1, 1962

By C. E. Lesher

THE Disco* process for the production of low temperature coke and its immediate predecessor, the Wisner or Carbocite process have been described in the voluminous literature of low temperature carbonization.1 This paper will describe the development of the process from the first attempt at commercial operation by the American Gas and Electric Co. at Philo, Ohio, Yn the 1920's to the successful operation in 1949 by the Disco Co., a division of the Pittsburgh Consolidation Coal Co., of the 1000-ton per day Disco plant near Pittsburgh, see Figs. 1-2. In the 1924 coal industry depression following the hectic post World War I expansion, the northern Appalachian, unionized bituminous coal fields were affected first and foremost, and Western Pennsylvania as hard as any. Competitive market pressure was heaviest on the lower grades of steam coals, notably the from the Panhandle district where ash and sulphur are inherently higher than in the same Pittsburgh coal bed to the east along the rivers. The firm structure of Panhandle coal while favoring the prepared sizes, depressed the usefulness and value of the finer sizes. Panhandle slack and nut slack were marketed with difficulty at consistent, and at times considerable, loss. Many solutions were suggested, and the Pittsburgh Coal Co. investigated all. Lower delivered prices through lower mine costs and more advantageous freight rates were obvious goals, but equally obvious were the difficulties of self attainment of either in any substantial measure. Selling Btu's in pipes was abandoned as an idea after a thorough study of the economics of distribution of what was then, and is even now, the only developed continuous process of complete gasification of bituminous coal-producer gas. Although the coal company purchased huge blocks of electric power, it sold not a car of coal to the central power stations. Public utilities controlled the markets for electric current, and it was found that no matter at how low a cost current might be put on the bus bars by the coal company, distribution to its widely scattered coal mines made such an enterprise practically impossible. Consolidation of underground operations and a huge modernization program of mining operations in the 1920's were but preparation for the introduction of mechanical cleaning of the coal for market, particularly the smaller sizes of steam, gas, and by-

Jan 1, 1953

By C. E. Lesher

THE Disco* process for the production of low temperature coke and its immediate predecessor, the Wisner or Carbocite process have been described in the voluminous literature of low temperature carbonization.1 This paper will describe the development of the process from the first attempt at commercial operation by the American Gas and Electric Co. at Philo, Ohio, Yn the 1920's to the successful operation in 1949 by the Disco Co., a division of the Pittsburgh Consolidation Coal Co., of the 1000-ton per day Disco plant near Pittsburgh, see Figs. 1-2. In the 1924 coal industry depression following the hectic post World War I expansion, the northern Appalachian, unionized bituminous coal fields were affected first and foremost, and Western Pennsylvania as hard as any. Competitive market pressure was heaviest on the lower grades of steam coals, notably the from the Panhandle district where ash and sulphur are inherently higher than in the same Pittsburgh coal bed to the east along the rivers. The firm structure of Panhandle coal while favoring the prepared sizes, depressed the usefulness and value of the finer sizes. Panhandle slack and nut slack were marketed with difficulty at consistent, and at times considerable, loss. Many solutions were suggested, and the Pittsburgh Coal Co. investigated all. Lower delivered prices through lower mine costs and more advantageous freight rates were obvious goals, but equally obvious were the difficulties of self attainment of either in any substantial measure. Selling Btu's in pipes was abandoned as an idea after a thorough study of the economics of distribution of what was then, and is even now, the only developed continuous process of complete gasification of bituminous coal-producer gas. Although the coal company purchased huge blocks of electric power, it sold not a car of coal to the central power stations. Public utilities controlled the markets for electric current, and it was found that no matter at how low a cost current might be put on the bus bars by the coal company, distribution to its widely scattered coal mines made such an enterprise practically impossible. Consolidation of underground operations and a huge modernization program of mining operations in the 1920's were but preparation for the introduction of mechanical cleaning of the coal for market, particularly the smaller sizes of steam, gas, and by-

Jan 1, 1953

Three transient phenomena have been observed and experienced in the operation of large solvent extraction mixer-settlers. These relate to the ability of the settler to discharge streams with low entrainments arising from different phase separation æproblemsÆ. The operation of large-scale laboratory and commercial solvent extraction settlers has been shown by a number of workers to be a dynamic process, especially at the feed end. Circulating flow patterns are common in all three organic, aqueous and emulsion phases. The circulating patterns in deep dispersion bands in long settlers are believed to form roll fronts that can travel down the settler length within the bounds of the dispersion band. Various physical models are proposed to illustrate the formation and movement of roll fronts within the dispersion band. Another transient phenomenon has been observed in commercial settlers operating without any dispersion band. Entrainment of the continuous phase in the advancing dispersed phase is at high and erratic levels. This supports the conventional separation model, which recommends the presence of a significant depth of dispersion band to æfilterÆ the secondary haze from the bulk separated phases. The third transient is the position and shape of the dispersion band within the settler. Large commercial settlers have been shown to exhibit high variability in both these aspects of the dispersion band. The elimination of all three transient phenomena in commercial settlers has been shown to be effective with an in-settler media of coarse size and moderate specific surface area. The effect of the media is two-fold: it dissipates both the circulating flows and the forward velocity of any roll fronts, and creates a stable deep dispersion band at the feed end that serves to trap secondary haze from the primary coalescence process. It is effective in treating both types of transients involving non-existent or excessive dispersion band depths. The media serves to enhance coalescence by providing a static surface of intermediate surface tension on which droplets can collapse. The random nature of the media also provides multiple stream splitting and re-combination, that presents further drop to drop and drop to media impingement, which in turn promotes coalescence.

Jan 1, 2000

By J. L. Hoover

The goal of the drill bit consumption study was to develop an equation(s) based on various components that affect bit drill wear and use the equation(s) to estimate the consumption of bits during production drilling. Drill bit data from various geographic locations were compiled and used to develop linear regression equations using the Microsoft Excel Software. Multiple drill bit consumption equations were developed and statistical analysis was used to verify the accuracy of those equations. The equations will allow mining companies to more accurately forecast drill bit consumption when evaluating new mine properties. This capability becomes increasingly beneficial to forecasting as the cost of consumables increases.

Jan 1, 2012

By F. G. Caballero, J. L. Gonzalez-Carrasco, S. Barrius, H. Carreon, M. Lieblich

"The grit blasting is a low-cost technique successfully used to enhance mechanical fixation of the implants through increasing their roughness. As a result of the severe plastic surface deformation, it produces subsurface effects such as grain refinement, hardening and compressive residual stresses which are generally evaluated with destructive techniques. In this research work, non-contacting and contacting thermoelectric power measurements are performed in blasted 316L VM and Ti-6AI-4V specimens using Ah03 and Zr02 particles which yield a coarse and a fine rough surface, respectively. This study correlates the microstructural changes induced by the grit blasting treatment and the limitations and advantages of each of the nondestructive thermoelectric techniques based on the Seebeck effect used to evaluate these biomaterials.IntroductionIt is well known that surface properties play an important role in metallic materials used in bio-medical applications. Since the biological response is correlated directly with surface properties it is comprehensible the intense activity in superficial modification by physics or chemistry methods in this field. Grit blasting, one of the most popular surface modification of metallic biomaterials, enhances the mechanical fixation of the implant through the increase in roughness [1-3]. Roughening is developed by bombarding the surface with a high-velocity jet of ceramic particles, being the final roughness a function of the processing parameters (pressure, distance, time, ... ) and blasting particles (nature, shape, size). As the plastically deformed surface layer tries to expand relatively to the intact interior of the specimen, residual compressive stress gradients develops perpendicular to the surface at shallow depths with a maximum value at a depth in the range of 5 to 60 µm. This surface treatment also may cause subtle variations in the subsurface material properties, such as increased hardness and grain size refinement, which are consequences of the significant plastic deformation through cold work. Blasted affected zones may extend to a depth of up to about 200 µm. The subsurface hardening and the near-surface compressive stress gradient playa beneficial role by retarding fatigue crack nucleation and further growth, ultimately extending the fatigue life of the metallic part [4]. In this work, two non-destructive thermoelectric techniques (NDTT), the non-contacting and contacting thermoelectric power measurements were used to analyze the subsurface induced changes on blasted Ti-6AI-4V and 316L VM specimens using Al2O3 and Zr02 particles. Detailed information on the microstructural induced effects and subsurface mechanical properties were published elsewhere [5-8]. Here the nondestructive evaluation of the involved microstructural changes is used to assess the global subsurface damage. Advantages of using nondestructive techniques during manufacturing are envisaged."

Jan 1, 2012

By Howard Keele

"The Whitewood Mine near Edmonton, Alberta, is owned by TransAlta Utilities Corporation and operated by Manalta Coal Ltd. Approximately 2 million tonnes of sub-bituminous coal is supplied annually to the Wabamun Generating Plant. A high water table, high groundwater pressure, and structural folds contribute to stability problems in the fine-grained overburden. Significant increases in coal recovery have been achieved in recent years through improvements in water management and mining methods. Agricultural capability of the post-mining landscape has also been improved following the completion of mining/ reclamation activities. Introduction The Whitewood Mine, located to the north of Lake Wabamun and seventy kilometres west of Edmonton, Alberta, is owned by TransAlta Utilities Corporation and operated by Manalta Coal Ltd. Figure 1 shows the location of the Whitewood Mine with respect to the city of Edmonton. The mine presently supplies two million tonnes annually of sub-bituminous ""C"" coal to the 582-megawatt Wabamun Generating Plant located adjacent to the mine. The area is characterized by a high water table-, rolling coal seams and an overburden that consists of muskeg, clay and various sedimentary layers of sand, gravel and fine-grained sandstone. These distinctive characteristics require careful attention in order to not only meet the coal delivery requirements of the Wabamun Generating Plant but also to do so economically. Historical Background A small-scale underground coal mine was opened in the Wabamun area in 1910 by the Conner Coal Mining Co. Ltd. Underground operations were continued by several operators until 1948 when the Alberta Coal Co. Ltd. opened a strip mine which was subsequently taken over by the Alberta Southern Coal Co. Ltd. in 1951. The small-scale strip opera"

Jan 1, 1985

AS I told you in the chapter on salts, saltpeter is a mixture composed of many substances extracted with fire- and water from arid and manurial soils, from that growth which exudes from new walls or from that loosened soil that is found in tombs or uninhabited caves where the rain cannot enter. It is my belief that it is engendered in these soils from an airy moisture that is drunk in and absorbed by the earthy dryness. Considering its effects, I do not know how to decide and say exactly what the nature of saltpeter is. The learned and very wise physicians find it salty and with a subtle sharpness both in taste and in their medical experiments. Considering its strong biting qualities, they decide to say that it is of a hot and dry nature; on the other hand when they see that it is engendered from the air and that when touched by fire it becomes inflammable and vaporous, and rises with a fearful impetus when mixed in powder for military guns, it manifestly shows itself to be of a hot and moist airy nature. And then when they see that it is shining and transparent with whiteness and is fusible in every fire in a manner corresponding to a thing of a watery nature, and since it. is heavy, it seems that it can be said to be watery in nature. To this is added the experience of touch and of the great cooling action which it has on water in summertime when wine is to be cooled, and since it crushes and breaks with but little pressure, it might be thought to be earthy in nature; especially when it is seen to change into a hard, white stone when burned with an equal amount of sulphur. Thus it seems that every one of the elemental qualities is predominant in it. Now the ancients called this, or a similar thing, nitrum. [150] Pliny, in Book XXXI of his Natural History, has said that it was a thing not much different from salt, that doctors do not seem to have yet known its nature, that it is found in various places, and that the best is found in Macedonia. But among the moderns and especially in our regions, it is not known today what it is that Pliny and other writers refer -to, since according to the aforesaid Pliny and other ancient writers it is a natural mineral. Some say that in place of, the natural kind the artificial will serve for the same medicinal purposes, since it has the same nature and is perhaps more powerful.

Jan 1, 1942

By Shueling Woo, Charles S. Barrett, Robert F. Mehl

When one solid phase is generated from another, fixed and rational orientation relationships are observed to subsist between the parent and the new crystal. The principle has been proposed1 that the relationships obtaining between the same two phases are identical whatever the type of phase change involved, or whichever of the phases may act as parent. Many types of phase changes have been studied: allotropic transformations in pure metals, precipitation from solid solutions, eutectoid decompositions, peritectic reactions, the formation of oxide layers, and others2 Phase layers generated by diffusion of one metal into another constitute an additional type of reaction. This report provides new data on the orientation relationships occurring between phase layers formed by diffusion, in the Cu-Zn system,§ and furnishes further evidence in support of the principle. Materials and Methods The Cu-Zn system is especially suitable for these studies since the high vapor pres- sure of Zn provides an opportunity readily to create one phase poorer in Zn upon a parent phase richer in Zn by removing Zn by vaporization, or to reverse this process by adding Zn from Zn vapor; e.g., the beta phase can be found as a layer upon gamma by dezincing, or gamma can be found on beta by addition of Zn from Zn vapor. Since orientation relationships are to be sought, requiring crystals large enough for orientation determinations, it is convenient to prepare single crystals or large grains of the parent phase. The samples were prepared from oxygen-free high-conductivity copper and Horse Head zinc by melting under a borax flux in a graphite crucible. Large crystals of beta brass were grown by the strain-anneal method, in plates sectioned from the cast ingots, by the following procedure. Rockwell-hardness indents were made at I cm. intervals and with various loads, then the plates were annealed for 4 days at 700°C. in Nichrome boxes packed with beta-brass chips and graphite. Surface layers were removed by grinding and etching to a depth of about 1.0 mm., and individual grains were cut out. Crystals of alpha and gamma brass were prepared by freezing, by lowering a graphite crucible at speeds less than one inch per hour through a furnace held at a constant temperature above the melting point. Single crystals were cut out with a jeweler's saw, ground, polished and etched. Care was taken to remove cold-worked layers from the finished crystals

Jan 1, 1944

By Charles S. Barrett, Robert F. Mehl, Shueling Woo

When one solid phase is generated from another, fixed and rational orientation relationships are observed to subsist between the parent and the new crystal. The principle has been proposed1 that the relationships obtaining between the same two phases are identical whatever the type of phase change involved, or whichever of the phases may act as parent. Many types of phase changes have been studied: allotropic transformations in pure metals, precipitation from solid solutions, eutectoid decompositions, peritectic reactions, the formation of oxide layers, and others2 Phase layers generated by diffusion of one metal into another constitute an additional type of reaction. This report provides new data on the orientation relationships occurring between phase layers formed by diffusion, in the Cu-Zn system,§ and furnishes further evidence in support of the principle. Materials and Methods The Cu-Zn system is especially suitable for these studies since the high vapor pres- sure of Zn provides an opportunity readily to create one phase poorer in Zn upon a parent phase richer in Zn by removing Zn by vaporization, or to reverse this process by adding Zn from Zn vapor; e.g., the beta phase can be found as a layer upon gamma by dezincing, or gamma can be found on beta by addition of Zn from Zn vapor. Since orientation relationships are to be sought, requiring crystals large enough for orientation determinations, it is convenient to prepare single crystals or large grains of the parent phase. The samples were prepared from oxygen-free high-conductivity copper and Horse Head zinc by melting under a borax flux in a graphite crucible. Large crystals of beta brass were grown by the strain-anneal method, in plates sectioned from the cast ingots, by the following procedure. Rockwell-hardness indents were made at I cm. intervals and with various loads, then the plates were annealed for 4 days at 700°C. in Nichrome boxes packed with beta-brass chips and graphite. Surface layers were removed by grinding and etching to a depth of about 1.0 mm., and individual grains were cut out. Crystals of alpha and gamma brass were prepared by freezing, by lowering a graphite crucible at speeds less than one inch per hour through a furnace held at a constant temperature above the melting point. Single crystals were cut out with a jeweler's saw, ground, polished and etched. Care was taken to remove cold-worked layers from the finished crystals

Jan 1, 1944

Thiess Dampier Mitsui's Moura-Mine is located in the south-eastern corner of Queensland's Bowen Basin, some 180 kms west of Gladstone. Current requirements of the open cut operation are to drill and blast 25 million cubic metres of overburden per year, consuming some 12,000 tonnes of explosive in order to meet the requirements of the mine's four operating draglines and one overburden shovel. By early 1985 it had become obvious that the existing drill and blast equipment and technology could not cope with the long-term needs of the open cut mining operation. Three 61R drills were in need of rebuilding or replacement. Bulk ANFO trucks working two shifts per day were unable to match the requirements of the four draglines dne to long travel distances, slow discharge rates and their inability to load water-resistant products into the increasing number of wet holes. This paper outlines the significant steps taken to introduce new equipment and technology and the resulting improvements in the mine's productivity and economics.

Jan 1, 1986

By J. A. R. Faucher

"Autogenous grinding may be an efficient and economical solution to your ore comminution problem.An important potential economic advantage of autogenous mills results from the availability of very large capacity units.Autogenous grinding could be more economical in terms of both capital and operating costs.Satisfactory pilot plant testing and thorough economic evaluation are required for a sound decision in comminution plant selection.INTRODUCTIONMankind's first weapon was probably the wooden club, but men soon learned to shape, smooth and polish stone for tools and weapons by pounding and rubbing them with sand and water. It was only about four thousand years ago that rocks were first broken to concentrate, smelt and return the metals they contained. In spite of our recent great technological advances we still break rock in essentially the same manner that was used thousands of years ago - by pounding, rubbing and squeezing - and we still waste much energy and metal in the process"

Jan 1, 1969

By Paul F. Kerr, Raymond F. Robinson

Uranium mineralization occurs in the footwall of the Sunshine vein from the 2900 to the 3700 level. Veinlets of uraninite associated with pyrite and jasper have been so extensively divided and recemented that units more than a few feet in length are seldom observed. The wall rock is St. Regis quartzite of the Belt series. The age of the uraninite, on the basis of isotopic analyses, is 750 * 50, which agrees with geological data suggesting that phases of the Sunshine mineralization are pre Cambrian. THE Sunshine mine in the Coeur d'Alene district, Idaho, is well known for its silver-bearing veins but prior to the summer of 1949 had not been recognized as a possible source of uranium. At that time, during a geiger counter reconnaissance by T. E. Gillingham, R. F. Robinson, and E. E. Thurlow, high radioactivity was noted and radioactive specimens were collected from the footwall of the Sunshine vein.' The detection led to the identification of uraninite-bearing veins, since explored jointly by the Atomic Energy Commission and the Sunshine Mining Co. After the occurrence was noted, the geology of the uranium deposit was studied by the Sunshine staff, and a laboratory examination of the ores was conducted at Columbia University. Several types of laboratory work were undertaken. Differential thermal curves were made of selected siderite samples and results from many more were secured through the work of Mitcham.2 X-ray diffraction and X-ray fluorescence analyses were employed on uraninite, jasper, and siderite. Chemical analyses were made through the cooperation of the Division of Raw Materials of the Atomic Energy Commission. General Geological Features Several silver-bearing veins cut the overturned north limb of the Big Creek anticline as mapped by Shenon and McConne1,³ while the Osburn fault, a long-recognized regional feature about a mile away, marks the north boundary of the Silver Belt. The Sunshine vein, Fig. 1, has a south dip more or less parallel to the 60" axial plane of the fold and cuts rocks of the Belt. Series, starting with the Wallace formation near the surface, continuing downward through the St. Regis formation, and probably extending into the Revett quartzite which lies below the bottom or 3700-ft level. The limb of the anticline is locally modified by secondary folds, one being prominently exposed in the uranian area along the Jewel1 crosscut near the Sunshine vein. Crumpling of the limb resulted from compression which formed the anticline and probably preceded the faults in which the vein deposits accumulated. Evidence of drag along these faults points to reverse movement in the uranium-bearing area and elsewhere. This is true of major faults in the mine workings, and the majority of faults which can be mapped, as pointed out by Robinson.' The St. Regis formation, as measured in the mine, appears to have an initial thickness of some 2000 ft, but the apparent thickness due to thickening during folding is some 3400 ft. Along the Sunshine vein the purple and green rocks characteristic of the Wallace formation in the nearby Military Gulch section p. 37 of ref. 5) have been completely bleached because of introduced sericite. Hydrothermal solutions acting on the wall rock have substituted for the original color a pale greenish cast, although no pronounced mineralogical change has resulted, as Mitcham has observed.' The silver and the uranium depositions appear to belong to distinct epochs resulting from several periods of emplacement. Likewise, multiple periods of deformation account for the faulting. Uraninite is generally associated with silicification, while silver . mineralization accompanies carbonate veins. Rarely, uraninite may be found in a matrix of siderite. Ordinarily uraninite formed prior to ar-gentian tetrahedrite. Where clusters of veins form a stockwork, uraninite-jasper veins often favor one trend while tetrahedrite-siderite veins favor another. During deformation, brecciation of the St. Regis quartzite provided openings between broken rock fragments for precipitation from vein-forming solutions. Fractures due to major breaks were filled during the first stages of vein formation, while later deformation displaced the first veins and provided new channels along which further mineralizing solutions proceeded. The uraninite veins, as the first formed, have suffered fracturing, displacement, and segmentation. Uranian vein segments uncut by faults and more than a few feet in length are rare or nonexistent. Siderite veins are more massive and often extend without a break for tens and even hundreds of feet. In general they show much less segmentation. While the siderite is usually later, there is an overlap in the periods of deposition, some earlier siderite veins being extensively segmented in much the same way uraninite veins have been broken. Vein silica is more extensively distributed than the uranium and iron mineralization it carries. Along the vein course concentrations of uraninite frequently fade away and barren white quartz continues, the transition often occurring within a few feet along strike or down dip. An example appears on the 3700-ft level where a uraninite vein, see Fig. 2a,

Jan 1, 1954