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By F. Keller, E. H. Dix

The use of magnesium as an alloying element in aluminum alloys has been limited, in general, to comparatively small quantities. In duralumin-type, strong aluminum alloys, magnesium is present to the extent of 35 to 3/4 per cent. and various grades of Magnalite and the "Y" alloy of the National Physical Laboratory of England contain up to 1 1/2 per cent. In this country small quantities of aluminum alloy sheet containing 4 per cent. magnesium are produced commercially. All commercial aluminum contains sufficient silicon to convert a portion of the magnesium added to the compound Mg2Si. It is well known that the solubility of both magnesium and magnesium-silicide decrease with decrease in temperature. It is, therefore, impossible to separate the age-hardening effect of the magnesium-silicide from that of magnesium, except by the use of aluminum of such high purity that the silicon content is negligible. The present paper is the fifth l, 2, 3, 4 of a series from the laboratories of the Aluminum Co. of America reporting the results of investigations of the equilibrium relations in aluminum-rich alloys made from the high-purity aluminum manufactured by this company. 5 Previous Investigations A number of investigations have been made of the constitution of the complete aluminum-magnesium system and several determinations made

Jan 1, 1929

By P. Wells

"In the past decade, there have been many developments in processing of nickel/copper sulfide ores. Improved pentlandite/pyrrhotite flotation selectivity with the use of new reagents, fine regrinding and Redox measurement (control) has led to increased pyrrhotite rejection and thus higher concentrate grades. Flash flotation has increased overall nickel and associated precious group metal recoveries. Recovery of both fine and coarse particles has been improved through an understanding of flotation cell hydrodynamics. The separation of copper from nickel in such ores has seen a similar level of development. From the late 80s to very recently, the use of flotation columns, the use of pyrrhotite depressing reagents and the improved understanding of the complex mineralogy of chalcopyrite, pentlandite and pyrrhotite have considerably increased copper / nickel separation efficiency. Copper concentrate with more than 30% copper and less than 0.5% nickel grade is now obtainable at 80-85% copper recovery from mill feed compared to 70-75% copper recovery with 30% copper and 1% nickel grade only a few years ago. Improved copper / nickel separation in milling operations has the potential to substantially improve the processing of the resulting concentrates and thus the overall return from the extraction of nickel and copper from sulfide ores.INTRODUCTIONNickel metal by itself or in alloys with other metals and materials makes a significant contribution to modern society. The relatively high price that nickel commands compared to other base metals is a reflection of the fact that, although abundant in the universe, nickel is sparingly distributed in the earth’s crust. There are two types of nickel deposits that are currently being exploited: complex sulfide ores and lateritic oxide ores. Lateritic contain no copper but in sulfide deposits, nickel– bearing minerals, principally pentlandite (Pn, [Ni,Fe]8S9), some millerite (NiS) and violarite ([Ni,Fe]S) are often found in association with copper-bearing minerals, mainly chalcopyrite (Cp, CuFeS2) and cubanite (CuFe2S3). The copper content of such ores can vary considerably from as high as 5-8% (in some Sudbury basin ores) to as low as 0.1% (in ores mined by Western Mining at Mount Keith, Western Australia and by Inco in Thompson, Manitoba). The valuable minerals Pn and Cp are almost invariably found associated with pyrrhotite (Po, Fe7S8) which along with nonsulphide rock has to be rejected to tails in the primary milling stage. The bulk concentrate from the primary stage is then treated to depress Pn and float Cp. A complete Cu/Ni separation at the mill would be highly desirable but this is not possible because of locking between a small fraction of the valuable minerals. As a result, Cu/Ni separation has to be carried out both during milling and during refining of the matte following smelting. At Inco, Jinchuan and in Norilsk, a chalcocite / heazlewoodite separation is made by flotation following slow cooling of the matte. In the present Sudbury Inco operations, Cu/Ni separation has not been conducted at the mill since 1991 and all Cu/Ni separation takes place at the matte processing plant. Because of the rising ratio of Cu to Ni in the ore, this strategy is under review and this paper describes some recent studies of circuits in preparation for possible installation of a copper / nickel separation circuit at Inco’s Clarabelle Mill in the Sudbury area."

Jan 1, 2004

By A Grace, C Sennersten, T Taylor, A Davie, R Lyu, D Pentecost, C A. Lindley, J Craig, L De Macedo Camargo

Many underground mine void spaces are not suitable for human entry due to unprotected roofs, instability or having an unknown safety state (eg if they are many decades old). Investigations of these voids may nevertheless be important for general mine safety, for example to detect propagating collapses or water accumulation, prevent accidental intrusion by new developments or drilling to reassess old spaces for re-mining. Robots are an ideal technology for investigating these spaces, especially flying, rotary-wing robots that can access and map vertical structures and spaces while avoiding rocks, water and mud that have accumulated on void floors. To operate in underground mines, we are developing customised unmanned aerial vehicles (UAVs) as well as interactive 3D virtual models of the vehicles and their underground environments for controlling vehicle operation and visualising incrementally gathered survey data. Using a game/simulation engine to provide an interactive interface for UAV operation makes it possible to orchestrate external spatial information and video feeds with in-game cameras for optimal visualisation that is not limited to the position, orientation or field of view of cameras mounted on the UAV. First and third-person points of view with respect to the UAV are provided, together with 2D and 3D gaze tracking to provide effective interfaces for geology and mine engineering experts without the need for specialist UAV piloting skills. Ongoing work is addressing the provision of greater levels of autonomy for these vehicles to support mapping well beyond the line of sight of operators and geological characterisation of rock surfaces using sensors mounted on them, including miniature X-ray fluorescence and Raman spectrometers. Gathered data is fed into more general 3D models of the mine, block models and orebody so that the UAVs function as elements of a mobile perceptual system for intelligent mining.CITATION:Sennersten, C, Lindley, C A, Davie, A, Lyu, R, Grace, A, Evans, B, Pentecost, D, Taylor, T, De Macedo Camargo, L, Craig, J, Salomao, G N, Hellicar, A, Biggins, D, Timms, G, Coombe, M, Shahriar, M S, Smith, G and Rahman, A, 2015. Unmanned aerial robots for remotely operated and autonomous surveying in inaccessible underground mine voids, in Proceedings Third International Future Mining Conference, pp 101–108 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By P. K. Guerrero, N. Arbiter

The correlation of power consumed by a tumbling mill with the dimensions, speed, and load has been attempted by three principal methods. One of these, the torque formula, has been reviewed critically elsewhere.' This approach, while analytical, disregards the individual motion and speed of the tumbling bodies and assumes that the gross geometry of the entire load is sufficient to establish the power requirement. A more general approach, using dimensional analysis, has been applied in this laboratory by the present authors1'1, and more recently by Rose.3 This disregards the internal conditions within the mill entirely and in effect is an empirical procedure for correlating data. Finally, the complete analysis of tumbling mill dynamics as first made by Davis' attempts to develop the power requirement from individual ball and rod paths and velocities. Although Davis' result is applicable only at a single speed for a given size and load it could be useful, since his optimum speed is at the upper limits of conventional tumbling mill practice. Where power values predicted by the Davis equation were compared with actual mill requirements, they were found too low for small mills and much too high for the largest mills. This suggested that the agreement with actual intermediate range requirements might be fortuitous, and the development of the equation was examined critically. The probable source of error was found to lie in an erroneous assumption made by Davis in converting the energy of ball or rod motion to power. With the same approach, but with different assumptions, a modified equation has been obtained which predicts results that are usually consistently high. This is to be expected, since it is assumed that there is no slip between load and shell and no interference among tumbling bodies. Both these effects should account for the difference. Development of Equation: When a cylindrical shell charged with a substantial weight of rods or balls is slowly rotated about a horizontal axis, the load surface first assumes an inclination that gradually increases to a maximum. Continued rotation results in failure within the load, characterized by a sliding of the top layers down the slope and a reduction in the angle of inclination. Further rotation again increases the angle, and the cycle repeats. If the speed is increased, there is continuous load failure and build-up and a continuous stream of rods or balls descends over the upcoming mass, which moves in circular arcs. At higher speeds the up-

Jan 1, 1961

By F. L. Wideman

This report describes a computer program that is used for the calculation of the coordinates and elevations of subsidence survey pins located by intersection. This program was developed for the Federal Bureau of Mines by the Numerical Analysis Laboratory, University of Arizona. These calculations, although relatively simple, are both tedious and time-consuming when computed with a desk calculator and trigonometric tables. In this survey, a large number of pins were surveyed repeatedly, and it was evident that both time and money could be saved by using a digital computer.

Jan 1, 1962

By D. Hinton, M. McCawley, R. C. Lantz, F. Pisano, C. Stanley

"INTRODUCTION Aerosols (5 um have not been shown to be consistently generated and characterized in inhalation chambers. Particle deposition in the lungs however may occur with particles as large as 25 um(1). Therefore, in order to closely simulate the atmosphere of an underground coal mine where the distribution is bimodal, with modes at S and 15 um (2), particles much greater than <1 um must be characterized for uniform mixing and size distribution within these chambers. The Hazelton Animal Exposure Chamber has been chosen because it has been best characterized for smaller particles (<1 um) (3), and is the major type used by most inhalation toxicology institutes such as Lovelace Inhalation Toxicology Institute and Battelle Northwest Laboratory.BACKGROUNDPreviously published studies on the inhalation of solid aerosols have attempted to characterize the distrition of particles of <2 um in diameter. There are no published reports of extensive work characterizing either the size distribution of particles <1 um or the concentration throughout the exposure chamber (Table 1).Table 1 shows the variability and sizes of several aerosols <1 um in diameter used in five previous chamber studies.Discussion of Previous StudiesThe study done by Bauermash, Bryan, Dickinson, and Burke (4)stated two major concerns in the development of the 6.5 ft. diameter chamber. The first was that a quantity of animals could be exposed to the same concentration regardless of the location of the animal, and second was that the chamber could be easily cleaned and decontaminated. The solution to the first concern required a circular chamber with the contamination air entering the chamber somewhere along the central axis. The animals could then be changed during exposure time so that each animal was exposed throughout the total volume."

Jun 1, 1988

Jan 1, 1947

By B. M. Eiter, J. Hrica, D. R. Willmer

"Mineworkers are routinely tasked with making critically important decisions about whether or not a hazard presents an imminent danger. Researchers from the U.S. National Institute for Occupational Safety and Health collected formative data to investigate mine safety professional perspectives on workplace examinations, which revealed a potential gap in how mineworkers are assessing risk. During interviews, participants revealed not having a systematic methodology for mineworkers to use to determine if a hazard is considered imminent danger. In this paper, we identify and describe three distinct categories of imminent danger complexity and discuss potential steps that could lead to improved identification of imminent danger situations. Finally, we identify potential practices to incorporate into risk management efforts, including feedback, communication and specialized training, to increase awareness of imminent danger situations. IntroductionIn recent years, the metal and nonmetal mining sector, as categorized by the U.S. Mine Safety and Health Administration (MSHA), experienced an increase in the number of fatalities occurring at mine sites. From 2013 to 2015, 69 mineworkers were fatally injured, twice the number of fatalities in each of the previous two years (MSHA, 2015a). As a way to address this increase, MSHA issued its P15- IV-01 program policy letter, suggesting that “miners would benefit from rigorous workplace examinations conducted by experienced and trained examiners” (MSHA, 2015b). The goal of these examinations is to find hazards in the field and mitigate them before they cause injury or death to mineworkers. While it is important to identify all hazards in the workplace, it is critically important to identify those hazards that are considered imminent danger because they require an immediate response to avoid a severe or even fatal injury."

Jan 9, 2018

By Lebeau M., P. Duguay

"The cost of occupational injuries and diseases in the mining industry in Quebec was estimated for the period of 2010 to 2012. The method used takes into account the financial and human costs assumed by employers, workers, and the community. To better direct research and prevention toward issues with the most significant consequences, the results are presented in various ranking tables, which stakeholders might find useful.RÉSUMÉ Le coût des accidents du travail et des maladies professionnelles dans l’industrie minière au Québec a été estimé pour la période 2010-2012. La méthode utilisée prend en compte les coûts financiers et humains endossés par les employeurs, les travailleurs et la communauté. Afin de mieux orienter les recherches et la prévention vers les problèmes ayant les plus graves conséquences, les résultats sont présentés dans divers tableaux de classement, qui seront d’une grande utilité aux parties prenantes. INTRODUCTIONThe mining industry is much safer today than it was 30 or 40 years ago, mainly due to a more qualified workforce, the use of automated equipment, and a corporate culture more focused on occupational health and safety (OHS); however, the number and the severity of occupational injuries and diseases continue to make this industry one of the most hazardous. In the province of Quebec, the mining industry accounts for approximately 0.4% of paid workers but is the source of 4% of fatal work accidents. It is, therefore, important to continue the prevention efforts already underway in the mining industry.The difficult global economy, which has affected the mining industry in the last few years, is an opportunity to reaffirm that sound management of OHS can have a positive impact on companies’ productivity and profitability. Occupational injuries and diseases are costly for the companies concerned and for society as a whole. Reducing their occurrence makes it possible to reduce not only the size of workers’ compensation board contributions but also several other financial and human costs."

Jan 1, 2018

By W. H. Class

The embrittling effects of oxygen, ozone, nitrogen, air, and surface residues, on NaCl has been investigated. The embrittlement by ozone and oxygen was found to be associated with the formation of a NaClO3 surface compound. In these cases the initial crack that was responsible for fracture (in a bend test) always nucleated at the corners between the tension and side faces. The behavior of air was very erratic and on certain days did not produce enzbrittlement. During these periods, crystals that had become embrittled by the ozone treatment completely recovered their ductility after a short exposure to the ambient atmosphere, It was established many years ago1 that considerable ductility could be obtained in NaCl single-crystal specimens if the crystal surfaces were dissolved in water either during or immediately prior to the test. The original interpretation of this effect by Joffe attributed the enhanced ductility to the removal of surface microcracks by dissolution. Later investigations2&apos;3 have suggested that the exclusion of air from the specimen surface is the criterion for extensive plastic flow prior to fracture. The air em-brittlement in this later work was attributed to the diffusion of gaseous atoms into the surface layers of the crystal, thereby impeding the movement of dislocations. This model satisfactorily accounts for the reembrittlement observed after further air exposure subsequent to the water dissolution treatment. However, the situation has recently become more complex by the observations in several laboratories4-t that under certain conditions air exposure does not impair the ductility of NaC1. It has also been recognized5 that improper drying operations after water dissolution can leave surface precipitates that lead to embrittlement. Cleavage defects on as-cleaved crystals can often be another source of embrittlement. In the present work the effect of the gaseous atmospheres nitrogen, argon, air, oxygen, and ozone, on the ductility of rock salt was studied extensively. The embrittlement resulting from oxygen and ozone exposures was found to be associated with the formation of a NaC1O3 surface film. It is suggested that certain atmospheres, one of which often can be ambient air, which inhibit the formation or favor the decomposition of this compound, can promote ductility. Thus one aspect of the Joffe effect is certainly related to the removal of surface compounds or complexes by water dissolution. The effect of surface precipitates that remain after drying operations and of cleavage defects were also studied. In neither of the latter cases was the embrittlement as severe as that found with a NaClO3 surface layer. PROCEDURE AND SPECIMEN PREPARATION The nature of the embrittlement produced by the agents mentioned above was studied by means of microscopy, mechanical testing, and X-ray diffraction. Specimens were cleaved from large crystals of optical quality sodium chloride obtained from the Harshaw Chemical Co., and, except for those tested in the as-cleaved condition, were given a 15- to 20-sec immersion in distilled water followed by a rinse in absolute methyl alcohol. The specimens were then blotted on a soft, absorbent paper, and dried by a few seconds exposure to a stream of warm, dry air. Such a procedure was found to give a control surface which was microscopically free of residues. (A few crystals were intentionally painted with a concentrated NaCl solution in order to investigate the effect of surface residues). All specimens were of 0.140 sq in. cross-section. Crystals prepared in the above manner were immediately placed in a gas train where they could be exposed to the desired gases for preselected periods of time. For the oxygen and nitrogen exposures, pure reagent-grade gases were employed. The ozone was provided in the form of an ozone-oxygen mixture (approximately 10 pct ozone) prepared by passing commercial grade oxygen over a strong ultraviolet light source. All gases were dried prior to their introduction into the train. Since argon was found to be completely inert in its behavior (i.e., residue-free specimens that were exposed to argon were not embrittled), it was periodically utilized to check the control specimen surfaces as well as the condition of the gas train used for aging the specimens. After exposure to the gaseous media in question, the crystals to be used for the measurement of the strain to fracture were transferred from the gas train to a protective oil bath (without further exposure to the atmosphere) where the tests were conducted in three-point bending. The apparatus was so adjusted that the load could be applied at a constant, continuous rate. Other Snecimens from the gas train were deformed

Jan 1, 1962

By Selim Coskun

In this study, tungsten matrix composites reinforced with 2 wt% TiC particles were mechanically alloyed (MA?d) for 3h, 6h, 12h and 24h. 1 wt% Ni is used as sintering aid which is added before and after mechanical alloying. Microstructural and phase characterizations of composite powders and sintered samples were carried out via SEM and XRD analyses. Furthermore, density and hardness measurements of as-consolidated and sintered samples were carried out. Additionally, DSC experiments were conducted to investigate the sintering behavior of the MA?d powders.

Jan 1, 2009

By Tiruvengala Padma, Nilesh Naik

Piles are common type of deep foundation elements used for the special bridges, transmission towers, Jetties, and tall structures. Lateral loads on the structures can be due to either earth pressures, wind, waves, impact, moving vehicles and eccentric application of axial loads or in combination of the loads. Hence the lateral capacity of piles plays a major role in determining the pile dimensions. The laterally loaded pile analysis is a soil-structure interaction problem as the lateral capacity of pile depends on the soil strength and stiffness parameters and its reaction to the lateral load on pile. The common approach to determine the lateral load analysis of piles is the Beam on Lateral Springs Method also known as “p-y” method. In this method the pile is modelled as a beam and supporting soil is modelled as lateral springs. This study is focused on the comparison of output obtained from three geotechnical softwares namely FB-MultiPier, L- Pile and Wallap. L-Pile Software is based on Finite Difference Method, Wallap on Horizontal Subgrade Modulus Method and FB MultiPier on Finite Element Method. Pile response in terms of deflection, shear force and bending moments under vertical and horizontal loads from above three software are compared and concluded.

Sep 1, 2022

By H. L. Overton, J. B. Lipson

The concept of sodium single-ion equivalent activity as developed by Gondouin, Tixier and Simard,&apos; was used to determine the filtrate resistivity-activity relationships for 150 laboratory and 49 field drilling muds. With the exception of the native and phosphate high-resistivity muds and the calcium-treated muds, the filtrate resistivity-activity relationships were found to be within 20 per cent of that for pure sodium-chloride solutions. Gondouin, et al,* previously suggested a method of treating the high-resistivity muds in quantitative electrical log analysis. A new treatment is presented which uses the P-alkalinity of the filtrate as a correlating parameter in handling the calcium-treated muds in quantitative electrical log analysis. INTRODUCTION Gondouin, Tixier, and Simard in 1957 introduced new interpretive procedures for analyzing the self-potential curve of electric logging. They re-emphasized the previous work of the Schlumberger brothers, Wyllie and others, and re-defined the activity concept in terms of a number which they termed the effective resistivity. Their procedures are particuarly effective when the connate-water resistivities are less than 0.08 ohm-m or greater than 0.3 ohm-m. For gyp muds where the calcium content is known, a procedure was presented which allows calculation of the connate-water resistivity with improved accuracy. These procedures assume that one of the fluids in the system is a pure sodium-chloride solution, but they are not limited by the assumptions. For the fresh and saline connate waters, for instance, it is assumed that the drilling mud filtrate is a pure sodium-chloride solution. For the gyp mud interpretive procedure, it is assumed that the connate water is a pure sodium-chloride solution. Brown,&apos; on the other hand, has suggested that it would be extremely fortuitous if drilling mud filtrates could all be treated electrochemically as sodium-chloride solutions, and he cites some examples where discrepancies exist. A study has been made of the deviations of sodium single-ion equivalent activities, an of drilling mud filtrates from that of pure sodium-chloride solutions. Drilling fluids in common use on the Texas and Louisiana Gulf Coast and laboratory-controlled muds were investigated. Using a cell patterned after Gondouin, et al, (Fig. I), the equivalent activities were measured. It should be remembered here that the activity measured is merely an index which uses numbers that represent the sodium single-ion equivalent activity a,., of the mud filtrate. The membrane potential developed across the cell was determined with a null-type potentiometer. The resistivities of the solutions were measured by the four-electrode method. The resistivity system was calibrated by using saturated KC1 solution as a standard. Chemical properties of the drilling fluids studied were measured with standard API-approved equipment for the particular property in question. For the activity measurements, two shale discs were chosen to serve as cationic membranes. These two discs were both 1 1/4 in. in diameter and, respectively, 1/4 and 1/8 in. in thickness. The membrane potential, Em, was determined using the shale discs as cationic selective membranes separating two standard sodium-chloride solutions of known mean activity. Then by comparing the constant Km in the following equation, with the theoretical value of — 59 mv at 75OF, the perfection of the membrane was determined. The variation of Km for the two membranes used in this experimental work, as well as one of the many unsuitable membranes, is shown in Fig. 2. The measurement of the activity of mud filtrate involves the balancing of its combined individual activities against a standard solution of known mean activity. At the point where there exists zero potential across the membrane cell, the activity effects may be assumed equal for all practical purposes. The mechanics of making a null reading of this sort requires having a large number of different mean activity solutions. A more practical method involves

By D. W. Alberter

I consider it a great pleasure and distinction to be invited to appear before your organization to discuss our experiences with a comparatively new system of what is known as a "Full Dimension" extensible conveyor system. One of these systems has been operating in our Diamond Smokeless Mine, Boltz, Pennsylvania, since 1959 servicing a continuous mining machines For those of you who are not familiar with this method of transportation, I would like to offer an explanation.

Jan 1, 1962

By Naj Aziz

A series of laboratory experiments were conducted on a variety of bolt types to examine the load transfer capacities of different profiled bolts in short encapsulation push testing. A 75 mm section of 150 mm long bolt specimen was anchored in a 75 mm long stainless steel tube using full resin encapsulation. Six types of different profiled bolts and two non - profiled bolts were tested. Bolts with higher profile were in general found to have greater shearing resistance and higher stiffness than low profile bolts. Widely spaced profiles allowed greater displacement at peak shear strength, and bolts with no profiles produced very link load transfer capability. Rough surfaced plain bolts showed a significant load transfer capability in comparison to a factory supplied smooth surface bolt which supports the belief that rusted bolts have higher lnad transfer capability that un-rusted bolt surfaces.

Jan 1, 2003

By Kazmierczak J. B., Klein E., Kinscher J., Lizeur A., De Santis F.

In this work, we propose to implement machine learning methods for the automatic classification of mining-related seismic data. The approach retained for the classification is based on a Convolutional Neural Network (CNN) which has been tested and applied to two different mining datasets: the active ore mine of Garpenberg (Sweden), currently under exploitation, and the abandoned coal mine of Gardanne (France), where mining stopped in 2003. The first step of the approach consists in creating a well classified (manually) database of seismic signals separated in different classes as a function of the seismic sources. The selected database is then divided into two groups: train, containing the 70% of the signals, and test, which contains the remaining 30% of the signals within the selected database. The learning phase of the algorithm consists in creating a classification model based on the train group, which is further validated on the test group. The application of CNN for the automatic classification of Garpenberg and Gardanne seismic data shows, respectively, that about 88% and 98% of the seismic events of the two sites can be properly classified. These results demonstrate that machine learning could be a powerful tool for microseismic monitoring in mining and post-mining environments, which could be further extended to the whole automatic processing of seismic data, including signal’s classification as well as microseismic event’s localization.

Apr 26, 2022

By T. W. Healy, W. J. Trahar

INTRODUCTION The flotation of minerals from their ores in flotation cells involves understanding many chemical and physical processes ranging from electronic events in the bulk mineral and in the mineral surface regime. molecular events at interfaces, the statics and dynamics of thinning and rupture of microscopic to molecular intefacial films, the fluid mechanics of bubble- particle events, the dynamics of air-water-solid colloid states in a flotation machine, etc. etc. D.W. Fuerstenau, whom we honour in this symposium has made unique contributions to many of these diverse physico-chemical and technological sub-processes. The present paper is concerned with a number of observations of the behaviour of minerals in flotation cells and the surface science of some mineral sulfide-water systems. We do not intend to be comprehensive in our analysis, but rather to highlight the challenges that face the scientific masochist who chooses to understand "froth flotationn. In what follows, emphasis is placed quite deliberately on technologically relevant, dynamic or realistic flotation processes i.e. the recovery in a froth of a given sulfide mineral particle of a given size and history from synthetic or actual ores in a flotation cell. The paper also attempts to use the understanding that is emerging from the area of photoelectrochemistry of colloidal

Jan 1, 1989

By R. Q. Shotts

Data are presented which show that fractions of varying densities from the same coals are oxidized at different rates by nitric acid. From oxidation data, the approximate quantity of "bright" and "dull" components may be calculated. Definite relationships between oxidation rate and rank are shown for density fractions from at least two bituminous coals. IN 1945, the Alabama State Mine Experiment Station initiated a program on the determination of fusain in certain coals of the state.1 Because of the lack of equipment and personnel necessary for microscopic examination, the chemical method2 was used exclusively. During studies of the distribution of fusain in fractions of various sizes and densities on a medium volatile coal, the author noted a higher rate of oxidation of the nonfusain part of the coal in the lower density fractions and the difference in rate became more marked the shorter the oxidation period used. Since durain and other "dull" components of coal have been reported3,4,5 to have higher densities than vitrain and the bright components, it appeared probable that the observed differences in rates of oxidation in the different density fractions were due to variations in petro-graphic composition. Such effects have been noticed by other workers.2,3 In order to obtain further evidence on this point, several Alabama coals of different rank have been separated into three or more fractions on the basis of density and their rates of oxidation determined, using the procedure specified for the determination of fusain, except that measurements were made at short time intervals as well as for the longer periods specified in the regular procedure. Significant differences in the rates of oxidation of the nonfusain part of the various fractions have been observed, and it is believed that studies of this type may make possible the identification of individual petrographic components or lead to methods for their semiquan-titative estimation. Properties of the Coals: Analyses and some properties of the whole coals studied are given in table I. The range in rank of the coals is not the widest possible within the state, but samples of the low volatile coals that occur in thin beds in the northeastern part of the state, were unavailable. The Clements bed is not, at present, considered workable. The coal is of medium volatile rank, quite friable, and very strongly swelling. Analyses of different size fractions show that the larger sizes are of higher rank than the smaller ones. Material passing the No. 50 sieve (all sieve sizes refer to the U. S. Standard Series) is close to high volatile A in rank, except for the size passing a No. 200 sieve, in which fusain is partially concentrated. Because of the variation in rank of the sizes of Clements coal, oxidation studies were made of two widely different size ranges. The + 1-in. material was crushed on rolls to about 1/8 in. and separated into five fractions by float-and-sink treatment in a benzene-carbon tetrachloride mixture. The — No. 4 + No. 8 and the — No. 4 + No. 50 size ranges tested overlap but the latter size was studied last with the expectation that it would include more oxidizable material than the first size. This proved not to be the case. Yields and properties of the specific gravity fractions oxidized are shown in table II. Milldale bed coal probably represents, as nearly as it is possible to do so, the "average" coal of the state. The material passing a No. 4 sieve was the only size range oxidized. It was divided into four specific gravity fractions. As in every case the heaviest fraction, which was essentially rock, was discarded. The Black Creek is the most extensive in area of

Jan 1, 1951

By R. Q. Shotts

Data are presented which show that fractions of varying densities from the same coals are oxidized at different rates by nitric acid. From oxidation data, the approximate quantity of "bright" and "dull" components may be calculated. Definite relationships between oxidation rate and rank are shown for density fractions from at least two bituminous coals. IN 1945, the Alabama State Mine Experiment Station initiated a program on the determination of fusain in certain coals of the state.1 Because of the lack of equipment and personnel necessary for microscopic examination, the chemical method2 was used exclusively. During studies of the distribution of fusain in fractions of various sizes and densities on a medium volatile coal, the author noted a higher rate of oxidation of the nonfusain part of the coal in the lower density fractions and the difference in rate became more marked the shorter the oxidation period used. Since durain and other "dull" components of coal have been reported3,4,5 to have higher densities than vitrain and the bright components, it appeared probable that the observed differences in rates of oxidation in the different density fractions were due to variations in petro-graphic composition. Such effects have been noticed by other workers.2,3 In order to obtain further evidence on this point, several Alabama coals of different rank have been separated into three or more fractions on the basis of density and their rates of oxidation determined, using the procedure specified for the determination of fusain, except that measurements were made at short time intervals as well as for the longer periods specified in the regular procedure. Significant differences in the rates of oxidation of the nonfusain part of the various fractions have been observed, and it is believed that studies of this type may make possible the identification of individual petrographic components or lead to methods for their semiquan-titative estimation. Properties of the Coals: Analyses and some properties of the whole coals studied are given in table I. The range in rank of the coals is not the widest possible within the state, but samples of the low volatile coals that occur in thin beds in the northeastern part of the state, were unavailable. The Clements bed is not, at present, considered workable. The coal is of medium volatile rank, quite friable, and very strongly swelling. Analyses of different size fractions show that the larger sizes are of higher rank than the smaller ones. Material passing the No. 50 sieve (all sieve sizes refer to the U. S. Standard Series) is close to high volatile A in rank, except for the size passing a No. 200 sieve, in which fusain is partially concentrated. Because of the variation in rank of the sizes of Clements coal, oxidation studies were made of two widely different size ranges. The + 1-in. material was crushed on rolls to about 1/8 in. and separated into five fractions by float-and-sink treatment in a benzene-carbon tetrachloride mixture. The — No. 4 + No. 8 and the — No. 4 + No. 50 size ranges tested overlap but the latter size was studied last with the expectation that it would include more oxidizable material than the first size. This proved not to be the case. Yields and properties of the specific gravity fractions oxidized are shown in table II. Milldale bed coal probably represents, as nearly as it is possible to do so, the "average" coal of the state. The material passing a No. 4 sieve was the only size range oxidized. It was divided into four specific gravity fractions. As in every case the heaviest fraction, which was essentially rock, was discarded. The Black Creek is the most extensive in area of

Jan 1, 1951

By T. E. Masoner

The struggle to get the minerals industry seriously interested in high intensity wet magnetic separation* has been difficult. The high capital cost of the equipment, the lack of basic research, the lack of operating information, and the diverse characteristics associated with different minerals and ores have prevented the development and use of HIMS-W on a wide scale. The Climax Molybdenum Company, a Division of American Metal Climax, Inc., located at Climax, Colorado, was among the first companies in the Americas in recent years to support the development of HIMS-W to recover weakly magnetic minerals on a large scale. The Climax Molybdenum Company, one of the world&apos;s largest underground mines, processes about 40,000 tons per day of ore, from which about fifty million pounds of molybdenum disulfide are produced each year. By-products include tungsten, iron pyrite, tin, and some monazite.

Jan 1, 1968