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By P. J. O'Connor, V. Gallagher

examined analytically in relation to the ratio of the

Dec 1, 1994

By Carl L. Shapiro, Jerome and Strauss

This is a critical examination of the theory that the amount of carbon necessary to form the iron-carbon (carbide) eutectoid is lowered by the addition of any carbide-forming element. Although this theory has been built up over a long period of years, it appears, in the light of recent published investigations upon the ternary constitutional diagrams of iron with carbon and other alloying elements, to be no longer tenable. A survey of these new results, summarized below, shows that (as is known) some metals lower the carbon content of the iron-carbon (carbide) eutectoid, whereas others raise it, but (as not heretofore clearly set forth) some first move the eutectoid in one direction and then, at higher concentrations, shift it in the opposite direction. Moreover, these differences in behavior exist even among the common alloying metals classed as carbide formers. PART I Influence of Body-centered Cubic Elements The effects of the various body-centered cubic metals (chromium, tungsten, molybdenum, vanadium, columbium and tan. talum) are reviewed individually. Iron-carbon-chromium System.—In the monograph on Alloys of Iron and Chromium, Kinzel and Crafts1 concluded that the carbon content of the eutectoid is lowered by increasing the chromium content. The quantitative influence of chromium on the eutectoid point of iron-carbon alloys was shown by Monypenny2 (Fig. I) and no data have been forthcoming to refute his findings. Iron-carbon-tungsten System.—Gregg,3 in the monograph on Alloys of Iron and Tungsten, accepted the data showing that tungsten decreases the amount of carbon required to form the eutectoid. The influence of tungsten on the eutectoid percentage of carbon as determined by Oberhoffer and Daeves4 is shown in Fig. 2; these results have received general approval. , I ron-carbon-molybdenum System.—In the monograph on Alloys of Iron and Molybdenum, Gregg5 reviewed the work of Guillet,6 Swinden,7 and ReedI8 all showing that molybdenum lowered the carbon content of the eutectoid, whereas Takei9 contradicted this conclusion. Svetchnikoff and Alferova,10 a little later, showed that large additions of molybdenum shift the eutectoid to the right. These last-named investigators found that molybdenum, up to 1.2 per cent, shifts the pearlite point and the point of maximum solubility of cementite in the gamma phase only slightly in the direction of lower carbon content; on the other hand, increasing amounts of molyb-S

Jan 1, 1944

By Jerome and Strauss, Carl L. Shapiro

This is a critical examination of the theory that the amount of carbon necessary to form the iron-carbon (carbide) eutectoid is lowered by the addition of any carbide-forming element. Although this theory has been built up over a long period of years, it appears, in the light of recent published investigations upon the ternary constitutional diagrams of iron with carbon and other alloying elements, to be no longer tenable. A survey of these new results, summarized below, shows that (as is known) some metals lower the carbon content of the iron-carbon (carbide) eutectoid, whereas others raise it, but (as not heretofore clearly set forth) some first move the eutectoid in one direction and then, at higher concentrations, shift it in the opposite direction. Moreover, these differences in behavior exist even among the common alloying metals classed as carbide formers. PART I Influence of Body-centered Cubic Elements The effects of the various body-centered cubic metals (chromium, tungsten, molybdenum, vanadium, columbium and tan. talum) are reviewed individually. Iron-carbon-chromium System.—In the monograph on Alloys of Iron and Chromium, Kinzel and Crafts1 concluded that the carbon content of the eutectoid is lowered by increasing the chromium content. The quantitative influence of chromium on the eutectoid point of iron-carbon alloys was shown by Monypenny2 (Fig. I) and no data have been forthcoming to refute his findings. Iron-carbon-tungsten System.—Gregg,3 in the monograph on Alloys of Iron and Tungsten, accepted the data showing that tungsten decreases the amount of carbon required to form the eutectoid. The influence of tungsten on the eutectoid percentage of carbon as determined by Oberhoffer and Daeves4 is shown in Fig. 2; these results have received general approval. , I ron-carbon-molybdenum System.—In the monograph on Alloys of Iron and Molybdenum, Gregg5 reviewed the work of Guillet,6 Swinden,7 and ReedI8 all showing that molybdenum lowered the carbon content of the eutectoid, whereas Takei9 contradicted this conclusion. Svetchnikoff and Alferova,10 a little later, showed that large additions of molybdenum shift the eutectoid to the right. These last-named investigators found that molybdenum, up to 1.2 per cent, shifts the pearlite point and the point of maximum solubility of cementite in the gamma phase only slightly in the direction of lower carbon content; on the other hand, increasing amounts of molyb-S

Jan 1, 1944

By Simon C. Dominy, Ian M. Platten

"Abstract - Gold-bearing quartz reefs commonly show extremely erratic and unpredictable grade variation, although gross geological continuity may be good. This type of variation is often described as being nuggety or having a high nugget effect and can be measured quantitatively using the semivariogram. Understanding of geological features such as reef texture and structure will provide improved models for the interpretation of assay data, drill core descriptions, etc. In this paper, a case study from the quartz-hosted gold occurrences in the Gwynfynydd mine, United Kingdom, is described. The work provides a starting point for models of lateral variation and demonstrates the types of structural and textural features that may be sought to give clues to the prediction of gold distribution in similar deposits. Gold deposition at Gwynfynydd is primarily associated with the reef footwall. The host veins form a discrete group of structures that may have been emplaced early in the sequence of quartz veins forming the reef. This potentially exposes them to a maximum number of dissection events during repeat dilations of the lode. Gold was deposited in the local porosity at extreme concentrations, equivalent to kg/t grades, when the host fissure had become filled with a porous framework of crystalline quartz and sulfides. Distribution of porosity varied laterally along the vein as the result of the formation of clump-like growths of minerals from the vein walls. The growth style is relevant to the distribution of gold although it may not be relevant to the occurrence of gold in a particular vein. The preservation of pores with some connectivity late in the vein fill sequence may be important in permitting continued but slow fluid flows. This facilitates effective fluid reaction with wall rock-derived methane, thus changing the relative rates of gold and quartz deposition in favor of gold. The textural studies explain the first-order control of nugget distribution at Gwynfynydd but do not allow for prediction and optimization of the resource estimation process. This is principally because of the very low geological continuity and poor predictability of the high-grade pockets. Nonetheless, the work does provide a clear geological explanation for the erratic nature of the gold. It indicates textures and structures that can be used to determine geological continuity of the goldbearing elements within the gross reef envelope."

Jan 1, 2001

By R. A. Morgen

THE binary system lead-antimony has been the subject of compre-hensive investigations in these laboratories by Dean1 and his associates. The effect of a third constituent on this system, particularly on the lead-rich alloys in which dispersion hardening ,was found, has a commercial value as well as an academic interest. This paper covers the effect of the addition of copper, bismuth and tin, all of which are likely to be found in commercial lead-antimony alloys, and is divided into three parts, as follows: I. The System Lead-Antimony-Copper II. The System Lead-Antimony-Bismuth III. The Lead Corner of the System Lead-Antimony-Tin These three systems are of three different types, and hence may be considered as covering three general kinds of additions. Bismuth forms no compounds with either lead or antimony and forms solid solutions with both. Copper forms several compounds with antimony as well as solid solutions but with lead it forms a two liquid layer system and no appreciable solid solution. Tin is soluble in both lead and antimony in the solid state and also forms a compound with antimony. The effect of small amounts of bismuth on the lead-antimony alloys is small, having no appreciable effect on the solubility of antimony. The temperature of the solidus floor is lowered appreciably by the presence of bismuth, cutting down the range of heat treatment. Copper, on the other hand, due to compound formation, increases the apparent solubility of antimony. The excess antimony is tied up with the copper finally and so is not available for dispersion hardening. The net result of addition of small amounts of copper is to shift the dispersion hardening peak of the

Jan 1, 1927

By I. Osvath, I. Gombköto, G. Mucsi, Z. Molnár

"In the present research, a deposited brown coal fly ash was used as raw material for geopolymer. The reactivity of the fly ash was altered using mechanical activation, which is one of the promising methods to improve bulk and surface reactivity. The mechanical activation experiments were carried out in a high energy density mill using 5 m/s circumferential speed, and various residence times (1, 3, 5, 10, 15 and 60 min). The effect of mechanical activation on particle size distribution was measured by a laser particle size analyzer and structural changes using FT-IR. Geopolymer samples were prepared from mechanically activated fly ash with an alkali solution. The progress of geopolymerisation was monitored using an Isothermal Conduction Calorimeter. The heat flow curve obtained indicated that reactions were more prominent and started much earlier in the mechanically activated samples. This observation is further supported by the compressive strength results which also improved in geopolymers using mechanically activated fly ash. Based on the obtained results, it can be inferred that mechanical activation is a possible way to enhance the reactivity of fly ash and consequently properties of resulting geopolymers.INTRODUCTIONCoal fired power plants generate fly ash and slag in huge amount worldwide, about 780 million tons/year (Heidrich et al. 2013). Due to the relatively low utilization rate, enormous quantities of these wastes are landfilled in ponds. The fly ash is the finest grained particle fraction of the solid ash, which is transported with flue gas, and removed by electrostatic or bag filters. The fly ash has pozzolanic activity, it does not react with water, but in the presence of calcium hydroxide solution hardens and solidifies, producing a reaction product practically insoluble in water (Opoczky, 2001). The most important property of the fly ash regarding geopolymerization is its reactivity, which depends on the chemical and phase composition, the dispersity (specific surface area, particle size distribution), and the morphology of the fly ash particles, and determined by the physical properties and chemical composition of the fly ash. Geopolymers concerning their chemical structure are polysialates, where the sialate (silicon-oxoaluminate) network is built up from the bonds of Si-oxide and Al-oxide by sharing oxygen atoms (Davidovits, 1988)."

Jan 1, 2016

By J. B. Scuffham, G. A. Rowden

The use of ammonia as a leaching agent has been well-documented but only recently have its advantages been fully exploited on a commercial basis. When compared with conventional sulfuric acid leaching processes, the major advantage of ammoniacal systems is their ability to reject iron and many acid consuming gangue materials. Although metallic copper, nickel, zinc, etc. are dissolved rapidly in ammoniacal liquors at ambient temperature in the presence of air the sulfide ores of these metals are more resistant to this treatment. Sherritt Gordon Mines in Canada treats sulfide concentrates at its Fort Saskatchewan plant under pressure with ammoniacal am- monium sulfate solution to solubilize the non-ferrous metal values. Typical leach operating conditions are 80-95°C and 115- 128 psig. Although the metals present in the ammonical solution could be recovered via solvent extraction techniques, Sherritt Gordon Mines currently operates a pressure reduction process using hydrogen to yield metal powders directly from the ammoniacal solution. The basic Sherritt Gordon technology has been applied world wide for the treatment of nickel/cobalt concentrates.

Jan 12, 1973

By Payal Bakshi, Sangeeta Tiwari, Mohini Saxena, Anusha Sharma

"Recycling and reuse is perhaps the most favorable and beneficial way to solve the problem of industrial waste disposal. However, the use of industrial wastes like fly ash, tailings etc is in practice for brick manufacturing, land filling, embankments filling etc. These existing practices do not add enough value to the wastes. Moreover, some wastes may have very good potential to be incorporated in valuable products like paints. This study reveals about the value addition of industrial wastes like fly ash, copper tailing and blue dust as an extender in paints. Comparative properties and characteristics of these three wastes for application in paints are discussed. Fly ash, copper tailing and blue dust were characterized for physical, chemical and mineralogical properties and used in different paint formulation based on their potential to the particular application. Fly ash has been found very useful in enamel, primers and flat paints while copper tailing was found suitable in oil based paint formulations. The performance of fly ash and copper tailing paints were evaluated by comparing with those of conventional whiting extender. Blue dust was compared with conventional iron oxide for use in priming coats. The extender properties of these new material and paints prepared out of blue dust, fly ash, copper tailing, were found better than the existing related materials.IntroductionIndustrial development and environmental reforms should run parallel to benefit each other. This is the best policy, which must be adopted by industries for the sustainability of the current modern life. The high degree of industrialization and urbanization adds scads of waste resulting problem of pollution and challenges of their safe disposal. The nature of waste depends on the process that produces waste as its by-product. Therefore, policies/plans are prepared by keeping the view of possible potential hazards. Among the different wastes some are generated in the industries, which have great importance in the country’s economy, like fly ash waste from thermal power industry and mining waste. In India the total contribution of thermal power in the total electricity generation is more than 70% and it produces about 123 million ton of the fly ash annually [1]. On the other hand mining plus extraction of ferrous and nonferrous metals also produce waste in million tonnes of categories [2]. Since the generation of this waste is very high they cover large land area for their disposal and dumping [3]. The storage of this waste in the dumping sites for long time duration may cause problem of land, surface water, ground water and fertile soil contamination [4]. As far as Indian fly ash is concerned it does not contain toxic element over the limits of hazardous waste [5]. However, in general most of the metals deposits are found in the form of pyrite based ores. Mining wastes contain toxic elements e.g. heavy metals in varying amount, which get mobilized when pyrite get oxidized to sulphate producing sulphuric acid [6,7]. These ores contain very less amount of targeted metals in themselves thus they require extensive preprocesses for concentration of the metals [8]."

Jan 1, 2008

By Charles B. Dugger

Sacrificial linings for grinding mills have been a necessary state of the art of mineral dressing since the inception of comminution. Long recognized as the final link in energy transmission from power line to ore, mill liners as a scientific endeavor have not expanded as rapidly as other branches of mineral dressing engineering. Several reasons for this technological lag are apparent. Typically in the past, labor intensive foundries were freely located geographically, at a time when transportation charges made up a significant portion of the casting cost. Alloying agents had not gained their current level of sophistication and were relatively inexpensive in the quantities required. Precise foundry controls were not economically justified, or totally understood. Coincidental to these elements, liner consumption per unit processed did not categorically contribute as a major cost item to the mill operator. Grinding equipment was small, and many times lining life exceeded that of the promoter. These unique conditions no longer exist. Ore dressing equipment has grown to meet modern mining demands. Larger processing facilities, utilizing fewer pieces of equipment, have replaced operations of the past. Emphasis today and tomorrow is on larger and larger equipment, with an eye on lower and lower unit processing costs.

Jan 1, 1979

By Amanda Cristina Medeiros da Silva

Este trabalho tem o propósito de avaliar a temperabilidade de um aço SAE 1040 através da utilização do ensaio Jominy e posteriormente promover tratamentos térmicos, gerando nos corpos de prova condições de arrefecimento diferenciadas para avaliar a influência da severidade de têmpera da salmoura e óleo. A curva de ensaio Jominy gerada apresentou um comportamento coerente para um aço com médio teor carbono. Já os tratamentos térmicos que foram realizados posteriormente revelaram que o meio que gera o maior acréscimo nas propriedades mecânicas é o resfriamento em salmoura, haja vista que os corpos de prova submetidos a este resfriamento apresentaram o maior de dureza.

Aug 16, 2017

By R. L. Bruening, L. Navarro, R. M. Izatt, N. E. Izatt, S. R. Izatt

Green chemistry principles will be discussed, and examples will be given of the use of Molecular Recognition Technology (MRT) to selectively separate valuable metals such as rhenium and palladium from various copper refinery feed streams. Recovery of these metals has numerous advantages including (i) conservation of valuable resources, (ii) prevention of environmental damage, and (iii) elimination of capital and operating expenses due to re-processing or disposal of metal-bearing streams. INTRODUCTION Refining of copper ores has a long and successful story. The history of copper, one of the first metals mined in human history, illustrates the global challenges faced as a result of increased demand for major metals and for by-product specialty metals found with them in trace amounts (Izatt et al., 2014). Copper has valuable properties, which have sustained its use over the centuries. It is an ideal material for creation of novel materials. Some desirable properties of copper that have proved valuable in our high-technology society include suitability for alloying with many other metals; ease of joining by soldering and brazing; good combination of mechanical qualities; high resistance to corrosion; suitability for many artistic purposes; and, of great importance in the modern era, efficient and economic use as a conductor of electricity. Copper mining in the U.S.A. began in the late nineteenth century in Montana (Izatt et al., 2014). The estimated total amount of copper mined globally before 1800 is about 5 million tons, four times less than is mined in a single year today (Flanagan, 2018). Production of copper in the U.S.A. has remained fairly constant at about 1,300,000 to 1,400,000 metric tons per annum from 2013 to 2017. Specialty metals such as bismuth, rhenium, molybdenum, and others that have become essential in our 21st century technology, and precious metals such as silver, gold, and the platinum group metals (PGMs) are concentrated by geochemical processes in trace amounts in copper ores. These specialty and precious metals were discarded into tailings in early mining operations, since limited extractive technologies existed and uses for most of them were limited. Thus, economic benefits for recovering them were limited, primarily, to silver and gold. Today, copper processing is the main, and often the only, commercial source for certain of these elements (Izatt et al., 2014). For example, molybdenite (MoS2) is the predominant ore mineral of molybdenum mining (Pohl, 2011). Cu-Mo-Au porphyry ore deposits supply ~75% of the world’s copper, 50% of the molybdenum, nearly all of the rhenium, and 20% of the gold. Typical ore grades are 0.5–1.5% copper, 0.01–0.04% molybdenum, and <1.5 g/ton gold. Molybdenite is the primary source for rhenium, among the rarest of metals, which is an essential component of super alloys, such as turbine blades in the aerospace industry (Pohl, 2011). Most rhenium is obtained as a by-product of molybdenite from copper mines in Chile. The case of rhenium raises an important issue. Continued availability of rhenium, selectively concentrated in copper ores, depends on continued mining and processing of copper. Since the mining company’s main interest is typically in copper production, continued recovery of rhenium and other specialty elements present in the ore body is at risk. Dependence of specialty metal supply on continued mining of major metals exists in several additional cases including indium, gallium, selenium, tellurium, germanium and bismuth (Pohl, 2011). PGMs, on the other hand, are typically mined for their own value, which far exceeds that of associated base metals. However, copper ores often contain marketable amounts of platinum and palladium, making their separation of interest, if this can be done economically.

Jan 1, 2019

Henry D. Hibbard, High Bridge, N. J. (Communication to the Secretary): There is one chemical factor which has not been considered in the author&apos;s tabulation of tests, but which is none the . less important because it cannot be practically estimated, and that is the element oxygen. This element has been, and probably will continue for some time to be, one of the great causes of the continual discrepancies between the chemical and physical properties of steel. Probably oxygen occurs, in important proportions, only in soft steel, such as that which we are now considering. In this steel its physical effect is to diminish tensile strength and elongation. The percentage of oxygen in the steel, under working-conditions that are as uniform as possible, is likely to vary inversely as that of the manganese, or perhaps, and more probably, it may bear even an inverse geometrical ratio to the manganese-content. At all events, to follow the author&apos;s plan, the line representing the loss of strength due to oxygen is probably a curve. Plotted by itself, the line would probably be straight; that is, the decrease in strength would be proportional to the increase in oxygen, but if the results were superposed on the percentages of manganese, they would give a curve, because the percentages of oxygen increase faster than those of manganese decrease. Were the oxygen-line to be developed and added to the diagram, it would seem that the manganese-line should then be straight. Due allowance for the effect of oxygen, therefore, would modify two features of the paper. It would increase the figure for the strength of pure iron from 38,000 to about 45;000 pounds per square inch, and it would straighten out the manganese-curve. The manganese-line in the paper is curved between 0.50 and 0.20 per cent. Above 0.50 per cent. it is straight, which may be ascribed

Jan 1, 1893

By Clarice L. Amaral, Ricardo Melamed

Clay-coating has been used as an environmental technology tool for the immobilization of toxic elements. The mechanisms of arsenate retention in clays suggest that not only the system pH is of fundamental importance in the process but also the character of metals and ligands that compose the electrolyte system. The goal of this study was to investigate the interactions between system pH and electrolyte ions on the retention of arsenate in an Oxisol soil. The sorption of arsenate decreases with the increase in system pH, reflecting the competitive sorption of arsenate with OH groups. Solutions containing Ca tend to favour the immobilization of arsenate in a relatively broad pH range.

Jan 1, 1998

By Frank G. Horino

The Bureau of Mines studied the uniaxial compressive strength of model rock pillars as a function of the angle and spacing of noncohesive planes of weakness. The model pillars were prepared from NX 2-l/8-inch diameter drill core of limestone, sandstone, and granite, and the planes of weakness were diamond saw cuts ground flat and smooth. The angle of the planes of weakness, measured from the horizontal, varied from zero to 57° in approximately 15° increments. When two planes of weakness were used, the thickness-to-diameter ratio of the wafer was 1/4, 1/2, and 1, Approximately 400 model pillars were tested in uniaxial compression. The results indicate that the uniaxial compressive strength of model pillars decreases rapidly as the angle of the plane of weakness increases from 30° to 57°, and that the spacing of these planes of weakness has only a minor effect on the strength. The effect of the number of horizontal planes of weakness, with a spacing of 1/4 and 1/2 of the diameter, upon the compressive strength of model pillars was also investigated. These results indicate that as the number of planes of weakness increases the compressive strength of the pillar decreases. Normalizing the data provides useful estimates of model pillar strengths for any rock type.

Jan 1, 1968

By E. L. Piper

Natural graphite has been known for many centuries, having first been reported as a distinct mineral form by Gessner in 1565. At that time, graphite was used extensively as pencil "lead" because of the ease with which it marks paper. It is a black, unctuous material found as flakes, lumps, or needles in scattered locations throughout the world. The less crystalline, or "amorphous", natural graphites are thought to have been formed from coal under conditions of high temperature and pressure. The more crystalline varieties, such as those mined in Ceylon, probably were precipitated from molten solutions or were pyrolyzed from gaseous carbon compounds. Recognition of the good thermal and electrical conductivity of graphite, together with its highly refractory nature, led to an increasing number of appli¬cations for this material. Clay and pitch bonded natural graphite has been used in crucibles, refractories, foundry facings, and other high-temperature appli¬cations. These forms constitute the most important current uses for natural graphite in the United States. Other products containing natural graphite include batteries, lubricants, pencils, brake linings, etc.

Jan 1, 1973

THE problem of reaction rates in the open-hearth process is essentially that of trying to form a fairly clear picture of the "chemical mechanisms" in the bath. Quantitative data on reaction rates would perhaps not be of much practical importance even if they were available; however, what few approximate data there are can be used in combination with data given in Chapters 16 and 17 to sketch a picture of the "chemical mechanics" of the open-hearth process that is consistent with essentially all the present available evidence. The result may later be found incorrect in many details but even so it will illustrate certain useful methods for obtaining a clearer understanding of the process. Consistent with the treatment in Chapter 15, but in simpler terms, we may say that chemical reactions in general involve the following elements or steps : 1. The reacting molecules are mixed together in space in such fashion as to favor collisions among them. 2. Units of what is usually an intermediate molecular arrangement called an activated complex are formed at a certain rate, depending on temperature and concentrations. 3. .These activated complex units decompose into the reaction products (this step usually assumed to be so rapid as never to limit the over-all process). 4. In any of these steps, heat energy may have to flow into, or away from, the reaction zone to permit the reaction to proceed. 5. The products of reaction will usually have to move out of the way to permit further reaction. The temperature factor enters mainly through step 2, and its effect is very marked. (What is called temperature is really the mean energy content of all the molecules of the substance involved; at any one temperature a certain proportion of the molecules will have much higher energy content than the mean value.) Various reaction rates measured at around room tem-

Jan 1, 1964

THE problem of reaction rates in the open-hearth process is essentially that of trying to form a fairly clear picture of the "chemical mechanisms" in the bath. Quantitative data on reaction rates would perhaps not be of much practical importance even if they were available; however, what few approximate data there are can be used in combination with data given in Chapters 16 and 17 to sketch a picture of the "chemical mechanics" of the open-hearth process that is consistent with essentially all the present available evidence. The result may later be found incorrect in many details but even so it will illustrate certain useful methods for obtaining a clearer understanding of the process. Consistent with the treatment in Chapter 15, but in simpler terms, we may say that chemical reactions in general involve the following elements or steps: 1. The reacting molecules are mixed together in space in such fashion as to favor collisions among them. 2. Units of what is usually an intermediate molecular arrangement called an activated complex are formed at a certain rate, depending on temperature and concentrations. 3. These activated complex units decompose into the reaction products (this step usually assumed to be so rapid as never to limit the over-all process). 4. In any of these steps, heat energy may have to flow into, or away from, the reaction zone to permit the reaction to proceed. 5. The products of reaction will usually have to move out of the way to permit further reaction. The temperature factor enters mainly through step 2, and its effect is very marked. (What is called temperature is really the mean energy content of all the molecules of the substance involved; at any one temperature a certain proportion of the moleculea will have much higher energy content than the mean value.) Various reaction rates measured at around room tem-

Jan 1, 1951

By P Brown, M Nagarajan, A Green, P Dare-Bryan

Coal loss is an important issue at many coalmines, with losses of five per cent being common. The type of loss varies from mine to mine but is dependent on mine strata, the drilling and blasting processes applied and the mining method used. Typical coal loss mechanisms from the drill and blast process are coal roof damage and edge loss. Usually a reduction in coal loss is in direct competition with the need to provide material that is well-fragmented and a muck pile that has the required cast percentage. These competing issues were addressed over a two-year period at a mine in the New South Wales Coalfields by implementing a five-step approach. This was centred around building an understanding of the coal loss mechanisms utilising proprietary heave- modelling software, measuring coal losses by comparing survey to drill and/or gamma logs and implementing appropriate coal loss reduction processes. The end result exceeded expectations with a 95 per cent reduction in coal loss. Mine excavation productivity was maintained and coal loss minimised to less than one per cent of the in situ coal block.CITATION:Nagarajan, M, Green, A, Brown, P and Dare-Bryan, P, 2015. Managing coal loss using blast models and field measurement, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 429–436 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By C. Vipulanandan

It is critical to monitor the ground conditions during excavation and drilling of boreholes during construction to identify possible changes in the soil and rock formations. Drilled shafts are increasingly used as foundations to support structures, bridges and other facilities in geomaterials such as soft-rocks and hard clays. Locating the bottom of the borehole during construction with the required design strength is critical. Hence developing a simple device that could be easily adapted/used with the drilling tool was of interest in this study. Determining the shear strength of the geomaterial in the borehole and at various elevations including the bottom of the borehole can lead to better quality control of construction by identifying the various layers based on strength. In this study, a down-hole penetrometer (DHP-CIGMAT) was designed, built, calibrated and tested in the field to determine its effectiveness in measuring the strength of soil/soft rock in the boreholes. Based on limited field tests, linear correlations between geomaterial strengths and DHP-CIGMAT deflection have been developed. The DHP-CIGMAT can be used to identify soils and soft rocks.

By M. T. G. Davis, J. V. Cleasby, H. J. Wright

Mining practice in the Kimberley Division of De Beers Consolidated Mines Limited by J. V. CLEASBY. B.Sc.. A.R.S.M. (Fellow). H. J. WRIGHT. B.Se.. M.Sc.. (Fellow). And M. T. G. DAVIES. B.Sc. (Visitor) T his paper highlights the changes that are taking place at De Beers Consolidated Mines Limited in mining methods, mechanization, and employment practices. De Beers has four underground mines in Kimberley itself (Dutoitspan, Bultfontein, De Beers, and Wesselton), and two open-cast mines outside Kimberley (Finsch and Koffiefontein). Emphasis is placed on the new method envisaged for Koffiefontein when it becomes an underground mine. The paper also includes notes on chemical drilling and on winding practices.

Jan 12, 1975