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By Mary Kama, Kaul Gena

"Magnetic skarn ore (MSO) is one of the major copper bearing ore extracted by the Ok Tedi Copper Mine in Papua New Guinea. Copper minerals are recovered by flotation while the iron not associated with copper are discarded as tailings. The objective of this investigation was to determine the iron ore reduction kinetics for the Ok Tedi MSO and ascertain if it can be processed to produce sponge iron for a mini steel plant in Papua New Guinea.SEM-EDAX analyses of the Ok Tedi MSO indicated 10.1% C, 30% O, 0.6% Mg, 1.1% Si, 21.1% S, 0.8% Ca and 36.2% Fe. Most of the iron is in sulfide form. Both naturally occurring and roasted sinters of Ok Tedi MSO samples of different particle sizes were reduced by charcoal carbon at three different temperatures and seven different reduction times. Analyses of the reduced products indicated a metallic iron content of more than 65 wt.% on average.Results showed that there was no significant difference in reduction between fluxed and control materials. Only a slight increase in kinetics with reduced particle size, hence the reaction rate constant (K) did not vary much within the temperatures investigated. Reaction kinetics increases with increasing reduction time at 900°C. Therefore, more iron reduction is observed with particles of 106 µm size. In addition, the results also confirmed that the reduction energy used was higher at 800°C and lower at 1,000°C. In summary, iron reduction can be improved but close monitoring of temperature and reduction times are essential to determine the reaction kinetics of the Ok Tedi MSO. INTRODUCTIONMost mines in Papua New Guinea mine large quantities of iron in the form of sulfides, carbonates, oxides and sulfates that are eventually disposed off as tailings. The Ok Tedi magnetic skarn ore (MSO) contains a significant amount of hematite, magnetite, siderite, ilmenite and pyrite that can be a source of iron. The mineralogical compositions of Ok Tedi MSO reveals more iron minerals than copper, yet all iron containing minerals are collected in the tails from the main copper production stream. Therefore, this study is conducted to investigate the possibility of producing direct reduced iron (DRI), or sponge iron, from the MSO. Such sponge iron may serve as the feedstock for electric arc/induction furnace based mini steel plants in Papua New Guinea."

Jan 1, 2016

By W. E. Pugh

The object of the following is to discuss a few of the problems encountered in the practical field application of reflection seismology. Very little has been published on this phase of the work and it is to be hoped that discussions will be presented by many seismologists who have met with these problems in the field. No attempt will be made to discuss the general principles of reflection prospecting, nor to outline the general field procedure. These phases have been presented more or less in detail in previous publications1 while economy of space and time prevents their being repeated or amended here. If, in the following pages, some criticism is offered of those who have already given their time and efforts to present valuable papers on reflection shooting, we trust that it will be accepted in the constructive light under which it is offered. We do not wish to give the impression that the following paragraphs represent ultimate achievement in field procedure; they are presented more to illustrate methods we have found satisfactory thus far. We believe that the following three subjects are inexorably linked with the continued future successes and more widespread use of the reflection method which, at the present time, is the most

Jan 1, 1934

By Theophili CN, Kapenis AP

Seismic tomographic imaging has been applied to determine the blast induced damage zones in bauxite pillars in underground mining. At the retreating stage, when pillar dimensions are reduced from 8 x 8 m to approximately 5 x 5 m, the' seismic tomographies reveal, through measurements of the P-wave velocities which is a measure of the degree of fracturation of the pillar rock mass, the presence of three zones within each pillar. In the external zone, where velocities recorded are below 750 m/s. extensive pillar damage occurs which is attributed to both the growth and coalescence of pre-existing cracks and even the creation of new cracks in the rock mass. This effect is in agreement with literature, when considering the peak particle velocity as a criterion for rock failure in tunnels. In the intermediate zone, where velocities range between 7S0-1000 m/s, damage to a much lesser extent occurs which is due mostly to growth of pre-existing cracks and widening of their apertures. The inner zone, where velocities exceed 1000 m/s, is considered to be unaffected by blasting. Simple remedial measures of low cost, which are based on blasting mechanics are proposed to minimise the blast induced damage zone and consequently the transition zone.

Jan 1, 1995

By Rob Thomas

"In Australia, a wide roadway is commonly defined as any roadway that is driven to a width greater than 5.5 m (18 ft). These roadways are typically required to enable the installation of longwall equipment (termed installation roads); however, other applications include the need to house conveyor driveheads and pre-driven recovery roads.As a result of the increasing size of longwall equipment and mine infrastructure, in some mines, roadway widths of between 9 and 12 m (30 and 39 ft) and are being developed.Accepting that these almost always constitute strategically important and often long-term roadways, this paper considers the use of: (i) an empirical roof support design model, which is based on over one hundred case histories, (ii) various roof support design principles, and (iii) commonly accepted strata management techniques.The paper demonstrates that wide roadways can be driven and supported to an acceptable standard providing due consideration is given to the prevailing ground conditions (including the quality of the immediate and upper roof strata, the Depth of Cover and the horizontal stressfield), the final width of the roadway and the required use of the roadway.INTRODUCTIONRoof behaviour and the associated roof support requirements in wide roadways, which are roadways typically driven to a width that is greater than 5.5 m (18 ft), are controlled by a number of key geotechnical and operational factors. The recognition of these factors is an important first step in the design process and it is imperative that each is considered in conjunction with local mine site information.The main points of note in this regard can be summarised as follows:• The greater the final width of the roadway, the greater the resulting surge in roof displacement on widening - note: a) see Figure 1 for a schematic illustration of the roof displacement trends typically measured during the development of the first pass and roadway widening, b) since displacement increases with roadway width, it is always recommended that the roadway width is kept to the minimum required and c) general buckling beam theory indicates that the capacity of any beams present in the roof will reduce in inverse proportion to any increase in roadway width squared (i.e., [final width2 -first pass width2] I final width2)."

Jan 1, 2010

By Leonard Bernstein, Harry Bartholomew

MANY of the properties of metals and alloys are structure dependent. Not the least of these is the grain structure. For example, in producing alloy bonds between silicon or germanium and gold-alloy foil at temperatures above their eutectics (which are, respectively, at 370" and 356°C) but below the melting points of the individual constituents, it was found that wetting was more complete with a fine-grain structure than with a coarse-grain structure. In cases where the assemblies were held together for long periods of time at elevated temperatures, wetting was not as critically dependent on the grain structure as was the case for shorter periods of time. When liquid phase forms, it first forms in the grain boundaries due to the fact that most of the impurities are concentrated at the grain boundaries and that most impurities tend to lower the melting point of the gold alloy somewhat. In addition, grain boundaries are at high-surface free-energy levels and are thus in a more favorable condition to initiate good wetting. A fine-grain structure will have more grain boundaries per unit area than coarse-grain structure thereby making wetting somewhat easier. To make the grain structure of an alloy sys- tem visible, a satisfactory method for differentiating between the different grains of which the system is composed must be employed. For the alloy bonding system previously described, the grain structure on the foil surface is of primary interest. Conventionally used etchants for the gold-alloy system will not adequately delineate grain boundaries in their structures. For this reason an alternate method is proposed for those cases where such a determination is necessary. Foil between 0.0005 and 0.005 in. thick has been used in this determination. The equipment used in this investigation was described in a previous publication.' Essentially, it employs a resistance-type filament which can be heated up very rapidly and cooled very rapidly. A thin refractory material is placed on top of the heating element. This refractory material may be molybdenum, tantalum, tungsten, or even ceramic but its thickness should be less than 0.010 in. to minimize the temperature gradient across it. The gold-alloy foil is placed on top of this refractory material. The temperature of the heating filament is raised to 900°C and cooled down to below 100°C in 5 to 10 sec. During this cycle, the foil can be observed to plastically deform due to its own weight. With no further chemical etching, this assembly is then viewed under a standard metallurgical microscope and the grain size measured. Fig. 1 is a Au-1 pct Sb alloy at 400X magnification and Fig. 2 is a Au-1 pct Ga alloy at 130X. This technique has proved to be an adequate means for controlling processing conditions in producing large quantities of gold alloy foil.

Jan 1, 1963

By Mark S. Stagg, Rolfe E. Otterness, Farrokh Djahanguiri

The U.S. Bureau of Mines (USBM) evaluated empirical equations that predict fragmentation from underground stope rounds. Controlled blasting is necessary for creating leaching stopes that maximize the recovery and minimize backbreak of the perimeter wall. This paper presents the fragmentation results from one of the three drop-raise blasts used to develop a reduced-scale cylindrical stope, 1.8 m in diameter and 6 m in height. The stope is located in the Colorado School of Mines Experimental Mine (Edgar Mine) in Idaho Springs, Colorado. This stope is part of a USBM research effort to determine the feasibility of incorporating in situ leaching of rubblized stopes into active underground metal and nonmetal mines.

Jan 1, 1994

By J. N. van de Merwe

CONTRIBUTION BYH. WAGNER AND T.T. OZAN The paper by Dr J.N. van der Merwe makes an important contribution to the design of bord-and-pillar workings in the Vaal basin. It has been recognised for some time that the strength of coal seams in the Vaal basin is markedly lower than that of coal seams in other coal-mining districts in South Africa. However, there was insufficient data to quantify how much weaker the extensively jointed coal the Vaal basin is. A number of recent pillar collapses that occurred at Sigma colliery, the only remaining underground colliery in the Vaal basin, provided Dr Van der Merwe with an opportunity to make this assessment.

Jan 1, 1993

By G. S. McCaa

Rock-dusting is an. effective means of preventing coal-dust from propagating an explosion in a coal mine, but it will not prevent gas from igniting-explosively and with much attendant damage locally. Ventilation must therefore be effective at all times, regardless of the employment of other explosion-prevention methods, if gas explosions are to be avoided. This paper describes a gas explosion which occurred in as bituminous mine that was well rock-dusted at the point of ignition and which exemplifies the value of rock-dusting, the necessity of maintaining effective ventilation, and the need of permissible rock-dusting machines receiving power from a permissible locomotive. Description of Explosion The mine in which this explosion occurred is developed on a panel system in a practically level seam; the panel entries are driven in pairs, and the air current intakes on the right entry and returns on the left entry. Near the mouth of the intake a door is placed to control the ventilation; board stoppings are placed in crosscuts, except the second from the face, in which a brattice cloth curtain is hung, the last crosscut is left open and line brattices conduct the air current from the last crosscut to the faces. In No. 7 entry the last cross-cut was 152 feet from the face, the line brattice being within 38 feet of this face, and the second crosscut was 250 feet outby the face of the back entry or return. Seven days prior to the explosion the intake and return entries were rock-dusted to within 38 feet of the face, and as the entry had advanced during the week, the rock-dusting was to be extended.

Jan 1, 1929

By H. M. Friede, R. H. Steel

Tin mining and smelting in the Transvaal during the Iron Age by H. M. FRIEDE*. Ph.D. and R. H. STEEL* (Visitors) This paper reviews the historical, archaeological, and metallurgical evidence on Iron Age tin mining and tin smelting in Southern Africa. The results of the analysis of twenty samples of tin ore, tin slag, and tin ingots found associated with Iron Age materials in the Transvaal (mostly in the Rooiberg area) are reported and discussed. The types of ingots preserved in local collections are described. A small experimental tin-smelting furnace was constructed and worked according to traditional African Iron Age technology. Qualitative and quantitative results of this experiment are reported.

Jan 7, 1976

By William F. Tanner

A river delivers a given load of sand, and hence of heavy minerals, into the sea into which it empties. This load is fixed by drainage basin characteristics and processes. Wave energy available for redistributing that load is fixed in an entirely different way. An equilibrium diagram of these two parameters (load versus energy) permits a tentative prediction of what will happen to the heavy minerals. The Chattahoochee River delivers a load which, over the past few thousand years, appears to have been greater than the available coastal energy could handle. As a result, much of the sand has been accumulated in various delta-margin features: barrier islands, beach ridges, and large furrowed off-shore shoals. The bulk of the trapped sand is found today in the shoals, which are attractive deposits for possible exploitation. If coastal energy levels are high enough to move the total load delivered by the river, accumulations of sand (and hence of heavy minerals) should be sought in the down-drift direction. Energy levels are rarely constant over any great length of coast. Decreases in energy may be due to widening of the shelf, convexity of, the shore, restrictions on the fetch, wave decay, or other causes. Such decreases result In deposition. Hydrodynamic mapping of coastal areas, as outlined here, should prove useful in the location of additional reserves. Part of this type of work can be done on maps, charts, and air photos.

Jan 1, 1962

By T. Glen Heslop, Dennis H. Laubscher

INTRODUCTION In all cave mining operations waste is drawn mixed in the ore, hauled, hoisted and milled. This waste usually contains some mineral which partly covers some of the costs of mining and milling it, but it still re- presents a loss of profits as the production rate from the mine is matched to the mill capacity - every tonne of waste milled replaces a tonne of profitable ore. Draw control aims to reduce the amount of waste drawn and to increase the amount of ore recovered. It is also used to regulate the grade of ore flowing to the mill and in block cave blocks to prevent potential stress build- up on the major apexes above grizzly drifts. This paper summarises what has been learnt about draw control in the forty years that cave mining methods have been used in the three largest underground chrysotile asbestos mines in the southern hemisphere. The four mining methods to which draw control has been applied are: a. Block caving. b. Shrinkage with overburden caving. c. Sublevel caving. d. Open stoping. Open stoping has been included because on a number of occasions severe falls from the back and side of these open stopes have occurred. Without full records of where and when ore is blasted, when and how much ore has been drawn from each of the drawpoints, it would be impossible to analyse the migration of ore and fallen waste in the stope. Several problems peculiar to chrysotile asbestos ore bodies affect the practice of draw control. Heterogeneous fragmentation, cavities, side pressures and the interaction of stresses in the caved ore affect the migration of ore under draw. Fibre is normally not developed uniformly throughout the ore bodies, values vary from place to place but there is usually a general decrease upwards and the hangingwall contact is an economic limit. The immediate hangingwall rock frequently looks like the ore body hostrock and is difficult to recognise in a drawpoint, and cannot be used as the marker for stopping draw. During caving or shrinkage, a large proportion of fibre becomes detached from the host rock and re- ports in the fines, which migrate differently to the larger rocks. The fines are not sticky, and flow easily if loose and dry, but compacted, the fibre and rock fines con- solidate the ore. During draw the proportion of fines in the ore varies considerably, as fines either flow relatively freely between the large rocks or become trapped and compacted above large rocks or hangups. This creates a large sampling error in drawpoint grade assessments, whether done visually or by bulk sampling, unless the assessments are done frequently. The method of draw control used is to regulate the draw rate in an attempt to lower the ore-waste interface as evenly as possible, and to finally stop working the drawpoint when a calculated tonnage has been drawn.

Jan 1, 1981

By Anderson J. M, Gillies A. D S, Jones N

There are a number of current theories in relation to methane migration and emission into workings following underground coal mining activity and some controversies do exist. Mining causes changes in the stress regimes in surrounding strata and results in fracturing. Permeability increases and methane flows into workings under a pressure gradient. The effects of stress on permeability depend on the physical properties of the coal and surrounding strata. Methane emission also depends on the original methane content and the proportion which will be liberated. There are several methods for determining in situ methane content and desorption characteristics of coal samples and several methane prediction methods but clearly more research is necessary to achieve an adequate predictive model.

Jan 1, 1992

By J. D. Embury, R. M. Fisher, A. S. Keh

An investigation of the defect structure and properties following large strain deformation has been carried out using transmission electron microscopy and mechanical testing for a range of ferrous materials and for copper. It is shown that, for a variety of ferrous materials, a cellular substructure is developed during the initial stages of working and on further deformation the dimensions of this substructure are reduced. Quantitative measurements of the flow stress and the scale of the substructure indicate that the strength of heavily worked materials is largely determined by the spacing of cell walls. These cell walls act as dislocation barriers in a manner analogous to grain boundaries. FCC materials do not harden as extensively as bcc after cold working and the present observations on copper indicate that the dimensions of the substructure in fcc materials are not markedly reduced on deformation. The differences between the fcc and bcc structures produced by large plastic strains are ascribed to differences in the extent of dynamic recovery. It is tentatively proposed that the greater stability of substructural barriers in bcc structures results from strong interstitial Pinning effects. It is proposed that for large plastic strains the work-hardening process may be considered in terms of the reduction of substructural-barrier spacing during the working process. This pvovides a simplified hut useful analysis of the strain hardening occurring during mechanical processes. THE mechanisms of strain-hardening processes have occupied the attention of numerous investigators over the past three decades and a multitude of theories have emerged in this field. The majority of previous work has been concerned with the development of a description of the plastic behavior of single crystals in terms of dislocation theory.'" In contrast, scant attention has been given to the strengthening mechanisms operative during mechanical working processes such as rolling and drawing. The large plastic strains involved in these processes make it difficult to correlate the observations with any elementary dislocation theory. Further, as Bullen and coworkers3 have opined, for large plastic strains both hardening and recovery occur simultaneously and thus it is extremely difficult to estimate the effect of plastic strain on the ambient internal stress field. It is probable that for large plas- tic strains any theoretical estimate of the internal stress field must be made in terms of complex dislocation groups. Although some valuable theoretical work has been done toward calculating the elastic properties of dislocation groups4 any detailed self-consistent model for large plastic strain is as yet impossible. With these limitations in view it is still of value to examine the mechanical properties of highly strained materials as a function of their substructure. This relationship is explored in the present communication for a variety of materials subjected to rolling, drawing, or swaging. The primary object of this investigation has been to establish the validity and the limitations of the substructural strengthening mechanism proposed by Embury and eisher' for drawn pearlitic wire and by Meieran and Thomas for drawn tungsten wire. No attempt has been made to delineate the basic interaction mechanism which occurs between a slip dislocation and the substructure and the authors believe that a great deal more experimental evidence must be compiled before these fundamental aspects can be explored. Also, no specific attention has been given to the detailed formation of substructure during working. Experimental Details. A variety of materials were used in this investigation, the compositions and heat treatment of which are tabulated in Table I. The commercially pure iron is referred to throughout this report as Ferrovac E. The mechanical working processes were all performed at room temperature. The wire drawing was performed on a manual drawing bench. Reductions of between 10 and 20 pct in area per pass were used in both swaging and drawing. The experimental parameter used to evaluate the mechanical properties of the materials was the 0.2 pct proof stress. This was determined for wire samples using an Instron tensile machine at a crosshead speed of 0.02 in. per min. The techniques for preparation of samples for transmission electron microscopy have been described previo~sl~.~ Specimens from wire samples were prepared from longitudinal sections and in some cases from transverse sections. To evaluate the substructural characteristics of rolled materials, thin foil samples were prepared of both the face and edge sections. Results. One of the more familiar ways of expressing work hardening in mechanical working is by the flow stress as a function of reduction in cross-sectional area. Fig. 1 shows such a plot for Ferrovac E eutectoid carbon steel and for copper. The curve for Ferrovac E is characterized by an initial stage of rapid work hardening and a final stage of rapid work hardening separated by an intermediate stage with a low rate of work hardening. This behavior is typical of many ferrous materials and the drawn pearlite wire previously investigated by Embury and Fisher is a more pronounced example. Copper shows an initial

Jan 1, 1967

By J. B. Cohen, S. L. Sass

The nucleation process for y', Ni3Ti, is shou'n to change from heterogeneous to uniform as the undercooling within the phase boundary increases. As unifornz nucleation beconres copious, (100) alignment is observed in the early stages of aging; howecer. whether or not the alignment is due to spinodal decomposition could not be determined. The presence oi a large-scale reversible segregation of titanium and not the intermediate precipitate y' may be the cause of the initial strengthening in this alloy system and the discrete regions detected magnetically by Ben-Israel and Fine. Evidence is presented for the role of dislocations in the formation at long aging tines oJ the equilibrium precipitate . ThE nickel-rich portion of the Ni-Ti phase diagram consists of a terminal fcc solid solution of titanium in nickel called y.' For temperatures below 1290°C if the solubility limit is exceeded and the temperature is high enough, the excess titanium will combine with nickel to form q, Ni3Ti, a four-layer hcp ordered structure with stacking sequence ABAC."~ Since a change in structure is involved, formation of q is slow and a metastable precipitate referred to as y' forms. This metastable precipitate is an ordered cubic phase in the unconstrained state having a structure similar to Cu3Au (LIZ) with the composition Ni,Ti."'5 From X-ray studies,8, 7 the following sequence is indicated for the precipitation reaction at low temperatures: 1) The appearance of satellites around low-index diffraction spots and splitting of high-index spots, indicating the formation of a slightly tetragonal phase in an imperfectly periodic arrangement. The tetragonal phase is y' or the depleted matrix, depending on the volume fractions of matrix and precipitate (and hence, the alloy composition); tetragonality apparently arises from coherency strains. 2) The appearance of diffraction spots from the equilibrium second phase, q. Ben-Israel and Fine'" used magnetic methods to measure the changes in matrix composition during aging, and to estimate the precipitate composition in a Ni-10.1 at. pct Ti alloy. They observed that the alloy, solution-treated at 1270°C and quenched, contained heterogeneities with discrete compositions which gradually vanished upon aging. It was suggested that y' may initially form as a defect structure with several possible compositions deficient in titanium as compared to Ni3Ti; the composition Ni3Ti develops with prolonged aging. The initial composition was Ni6Ti which would require a very large deviation in stoichiometry for y'. It was noted that at 700°C the precipitation reaction was 80 pct complete after 2 hr and that the volume fraction of second phase was 0.2 after 1 hr. Mihalisin and Decker' suggested that the equilibrium precipitate, besides being nucleated at grain boundaries, could also form at stacking faults. ~errick" examined the formation of in Ni-Cr-Ti, and suggested that a collapsed vacancy cluster within y' acted as a nucleus for intragranular q at high temperatures, 820" and 900°C. After long aging times at lower temperatures, 650" and 750°C, diffraction patterns taken from regions containing ribbons of stacking faults showed spots associated with q. Aging greatly enhances the mechanical properties of these alloys, even at high temperatures, and the metastable precipitate y' is thought to be responsible.' At 600°C the hardness of a Ni-10.1 at. pct Ti alloy increases rapidly during the first 20 hr of aging and continues to increase slowly thereafter.'" At 700°C the hardness reaches a maximum at 1 to 2 hr and then decreases.l1 In this paper the kinetics of formation of y' and the mechanism of transformation to in a Ni-Ti alloy are described. Evidence is presented that suggests that large-scale regions of titanium segregation are present initially and these may have an important influence on the initial strengthening of the alloy: these regions may be the heterogeneities detected by Ben-Israel and Fine. I) EXPERIMENTAL TECHNIQUES The Ni-10.3 at. pct Ti-0.6 at. pct A1 alloy was prepared by vacuum melting. Its chemical analysis is given in Table I. A 0.007-in.-thick strip was sandwiched between foils of the alloy and placed in an open Vycor tube with titanium chips (to get oxygen) and solution-treated for ; hr at 1150°C in a Globar Furnace under a flowing argon atmosphere. Following a quench into an ice-brine mixture at -5" to -2"C, a sample to be aged at temperatures up to and including 700°C was sealed in an evacuated Vycor capsule before being put into a fused salt bath. Aging above 700°C was carried out on bare samples in a salt bath. When removed from this bath and quenched into an ice-water mixture, the sample was normally coated with a thin layer of oxide easily removed with emery

Jan 1, 1970

By Savage E. N

Two genetic types of base metal deposits occur in the Wainivesi area of central eastern Viti Levu. The Wainivesi deposit is now considered to be a stratiform volcanogenic type, and the Wailotu and Wainiviti deposits are described as contact metasomatic with some hydrothermal manifestations. The Wainivesi mineralization is correlated with the Tertiary "e" stage, i.e. uppermost Oligocene-Iowermost Miocene. Tertiary "e" stage rocks in Fiji are therefore potential ore producers of stratiform volcanogenic type. On the basis of plate tectonics with Fiji part of the New Hebrides Arc prior to rifting apart in the late Miocene, stratiform volcanogenic deposits of the Wainivesi type may also occur in rocks of comparable type and age in the New Hebrides.

Jan 1, 1976

By J. T. Kalala

Energy consumption and wear of grinding media and liners are the major cost factors in milling plants. Since the beginning of the last century, much effort has been directed at the prediction of the power draw as affected by the mill operating conditions. This paper explores the prediction of the liner wear using the discrete element method (DEM). A mathematical model taking into account adhesion, abrasion and impact wear which occur in dry mills is derived in order to predict the loss of material on liners. The mathematical model is implemented in the DEM code using an objective function in order to produce realistic simulated profiles. Our DEM simulated predictions are compared to published experimental and industrial data. Keywords: modelling; discrete element method; liner wear

Jan 1, 2004

By Saghafi A

Spoil piles are produced routinely in open cut coal mines. Spoil piles may contain waste coal and other carbonaceous horizons. Coal and carbonaceous materials react with oxygen in the atmosphere, producing heat. If the rate at which heat is generated is greater than the rate at which heat can be dissipated, the temperature of the spoil pile rises. If the heating remains unchecked, spontaneous combustion can occur. Spontaneous combustion poses significant safety, environmental and economic problems if it should become established in spoil piles. Using the basic features of self heating in spoil, the use of model is directed toward developing quantitative prediction of spontaneous combustion in open cut coal mine spoil Piles.

Jan 1, 1998

By Takao Yasugi

The majority of copper in the raw material migrates to the de-copperized dross that forms when the crude lead produced in the blast furnace is treated in the de-copperizing process. The de-copperized dross is treated in the electric furnace producing matte, speiss, and crude lead. The de-copperized dross also contains the silver. Therefore, it is important to improve the rate of silver migration to the crude lead. For this reason, the behavior of silver between the matte, speiss and crude lead phases was examined. At the same time, several tests to improve the percentage of silver migrating to crude lead were conducted.

Jan 1, 2003

By P. L. Yorio, D. R. Willmer

"The current paper presents the results of a study designed to explore the types of practices that are fundamentally important to developing and maintaining comprehensive risk-based health and safety management systems (HSMS) in mining organizations. Eighteen practicing health and safety (H&S) executives, managers, and professionals from a variety of mining commodities were asked to assess the fundamental importance of 20 distinct elements and 133 different practices assembled from a review of several HSMS consensus standards. The research approach assumes that developing and maintaining a robust HSMS requires unwavering attention to activities designed to either: 1) directly contribute to a risk management system’s plan-do-check-act cycle; or 2) build an organization’s internal infrastructure without which the cycle cannot be sustained. The results of this study suggest that the following areas require consistent focus and attention: Leadership Development; Accountability; Knowledge, Skills, and Abilities Development; System Coordination; Culture Enhancement; Behavior Optimization; and Risk Management Studies. Each element and its corresponding top-ranked and top-rated practices are discussed.INTRODUCTION Since the time of the Industrial Revolution, occupational health and safety (H&S) management has been a topic of practitioner thought and academic inquiry (1). In the U.S., decades of regulation and research have resulted in a surplus of prescriptive information (techniques, tools, approaches, standards, programs, practices, policies, etc.). With an abundance of such information, a simple H&S solution to address a problem in the U.S. mining industry may seem straightforward. Counter to this assertion, however, some evidence suggests that the abundance of information may create complexity and cause confusion in the minds of organizational leaders and H&S managers, ultimately discouraging the voluntary pursuit of a sound approach (2). In line with this perspective, in 2006 the U.S. National Mining Association (NMA) formed an independent commission to examine H&S management issues within the mining industry. The findings of the commission called for the mining industry to adopt a risk-based management paradigm. In the presentation of its findings, the commission stated that “…every mine should employ a sound risk-analysis process, should conduct a risk analysis, and should develop a management plan to address significant hazards identified by the analysis” (3). Grounded in the well-known plan-do-check-act cycle, the recommended risk management system allows for mines to ground strategic management choices in their mine-specific hazards and risk profiles"

Jan 1, 2015

By R. D. Brittain

In order to analyze and control the transport of harmful trace-element impurities in various smelting processes, it is necessary to have fundamental information about the chemical thermodynamic properties of the pertinent condensed and vapor phases. This paper describes recent thermodynamic studies of the gaseous arsenic sulfides and of the activity of arsenic in a copper-iron sulfide matte phase. These studies were carried out by high temperature mass spectrometry and by effusion vaporization techniques, which permitted clear identification of the molecular species involved, a decided advantage in such complex systems. The nature of the results obtained and comparisons with previous interpretations will be described.

Jan 1, 1983