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By Hooman Askari-Nasab

Open pit mine plans define the complex strategy of displacement of ore and waste over the mine life. The objective of the mine plan is to maximize the future cash flows within the technical and physical constraints. Various mixed integer linear programming (MILP) formulations have been used for production scheduling of open pit mines. In the MILP formulation the slope constraints guarantee that all the overlying blocks are mined prior to mining a given block. Traditionally, the slope constraints have been modeled with cone templates representing the required wall slopes of the open pit mine. The overall pit slopes constructed by these templates are a function of the width and height of the geological block model. Therefore, the overall slopes are fixed in one bearing. This paper presents a general MILP model for open pit mine scheduling with variable slopes constraints. The methodology utilizes a directed graph to capture the precedence of extraction of blocks and pit slopes in different bearings. Depth-first-search algorithm was used to traverse the graph for constructing the slope constraints in the MILP problem. TOMLAB/CPLEX was used as the implementation platform to efficiently integrate the mathematical solver package CPLEX with MATLAB. A case study on intermediate scheduling of an iron ore mine over twelve periods was carried out to validate the models.

Oct 1, 2009

By Fred H. Seymour

In spite of the progress made by geostatistical theory over the years, evaluation of low grade open pit gold deposits continues to be challenging. Many Carlin type deposits are modelled from exploration drilling spaced on 10C foot centers. From these drill holes, 50 by 50 by 20 foot blocks containing about 4000 tons of material are estimated. The block size is a compromise between being large enough for a good geostatistical estimation and being small enough for practical pit limit analysis and mine planning. Most of these gold deposits are highly variable and include ore and waste zones that are too small to be properly defined from exploration drilling information. Because of this, selective mining is controlled by sampling closely spaced blast holes where the density can be as high as 50 blast holes per exploration drill hole intercept. Figure 1 illustrates an example of the ore/waste contact definition before and after blast hole sampling. With exploration information only, a tentative ore/waste contact can be drawn between the exploration blocks.

Jan 1, 1989

By C Sellens, L D. Fabbro, S Vink

The Fitzroy River Aqua-Eco Health Project is a collaborative research project between the Central Queensland University, the University of Queensland and BMA. It is designed to assess the aquatic ecology and health of the streams within the Fitzroy catchment located adjacent to mine sites. The universities are conducting an independent sampling program expected to yield the most comprehensive monitoring to date. The project design incorporates in situ testing of water quality variables including temperature, dissolved oxygen, conductivity, oxidation reduction potential, pH and turbidity. Water and sediment chemistry incorporate testing for sulfate, suspended solids, nutrients and metals. This sampling is complemented by quantifying changes in the abundance and diversity of a wide range of biota, including microbial, macro invertebrates and fish.This paper will detail the program and highlight some of the particular difficulties in conducting this type of research in ephemeral stream systems. Case study examples will be used to illustrate insights being gained from the program. CITATION:Fabbro, L D, Vink, S and Sellens, C, 2013. The Fitzroy Aqua-Eco Health Project, in Proceedings Water in Mining 2013, pp 117-120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By C. W. Parmelee

THE ideal fuel for burning ceramic wares is the one that, among other characteristics, has little or no sulfur. For that reason wood was long considered the most desirable fuel but its high cost has practically eliminated its used except in regions where it is very abundant or other circumstances warrant its choice. The fuels commonly employed are natural and producer gas, oil, and coal. The last named is undoubtedly the most important, not only in this country but abroad. Occasionally anthracite is used but the larger part is bituminous. The quality of the coal used depends on the kind and the value of the products being manufactured. For some materials, such as common brick, hollow block, etc., the quality of the coal is of less importance than in the manufacture of polychrome terra cotta, pottery, porcelain, etc. It is obvious that in burning clays that contain notable amounts of pyrite, marcasite or gypsum, as is the case with many common clays, the sulfur content of the fuel is of much less importance. The permissible amount of sulfur in the coal used will depend on the kind of product being manufactured. "A good sample' of coal commonly used in pottery ovens has something like this quantity of sulfur." PER CENT. Total sulfur 1.20 Sulfur in the ash 0.11 Volatile sulfur a 1.09

Jan 9, 1919

By V. J. Decarlo, J. J. Gilman

POLISHING pure zinc differs somewhat from polishing less reactive metals. The problem is not that of finding a suitable reagent, but rather of producing the polish in such a way that the surface remains polished after it is removed from the polishing bath. In other words., the anodic film that is vital to the polishing mechanism' must be tightly adherent and nonporous. It is usually desirable that it be thin. Polishing solutions consist of proper proportions of an acid and a strong oxidizing agent. In electro-polishing, the external circuit acts as the oxidizing agent. The proportions are critical because the essential surface film must be maintained at approximately constant thickness during the polishing process. In the case of zinc, chiefly two oxidizing agents, chromic and nitric acids, have been used. The simplest polishing reagent is concentrated nitric acid. However, it has certain disadvantages. It tends to pit: an excessive amount of heat is evolved during polishing; and the oxide film that it produces is not very stable, so that the polished sur-

Jan 1, 1957

By L. A. Creglow

IN common with many other companies engaged in the mining and processing of ores, research has always been an important activity of the United States Smelting Refining and Mining Company. Much of this research has been carried on at the various plants of the Company by the operating staffs, and over the years has been an essential factor in developing new methods and improving existing methods of operation. In 1917 arrangements were made with the Massachusetts Institute of Technology under which the Company had the exclusive use of one or two small laboratories in the then newly constructed MIT buildings and the use of the metallurgical laboratories, subject of course to the Institute's needs. After about two years this work was temporarily discontinued but was resumed in 1920 under the direction of G. H. Clevenger, consulting metallurgist for the Company, who recently retired. Becoming cramped for space, the laboratory was moved to a location near MIT on Amherst Street, Cambridge, in 1924. Establishment of a general research laboratory in metropolitan Boston naturally followed from the fact that the head office of the Company was located there and that the library facilities available for all types of research were, and are, unsurpassed. The disadvantages in carrying on research at great distances from the operating units of the Company were always apparent, but with widely scattered plants this disadvantage could not he overcome. With

Jan 1, 1948

By G R. Hancock, W D. D P Welivitiya

is placed in a waste rock dump, which is usually later reshaped to be erosionally stable, initiate and sustain vegetation and ultimately integrate with the surrounding undisturbed landscape. However, it is unclear how this exhumed material will weather and evolve for most sites. Also, there is a lack of data on the weathering of post-mining materials. If weathering is better understood, then there is the potential to improve rehabilitation outcomes. To improve predictions of the evolution of soil properties and weathering-limited erosion, estimating the rate at which fine, transportable material is produced from the weathering of larger, non-transportable particles and the resultant fragment size distribution and how that distribution evolves over time is necessary. This study examines the weathering process for four different coalmine waste rock materials for a Bowen Basin, Queensland site. Materials obtained from various areas of the coalmine were subjected to cyclic wetting and drying and heating and cooling. Particle size distribution and other material properties were explored after each experimental cycle to ascertain how the material changes during the experimental cycles. The particle size distribution data of wet and dry cycles were used as input data in a numerical weathering model to explore the dynamics of the weathering process for each material sample. A Monte Carlo framework was employed to assess the geometry of the weathering products, weathering rate and the number of daughter particles produced within a weathering cycle. Then the SSSPAM Landscape Evolution Model was used to evaluate the influence of weathering on erosion and landscape evolution of a post mining landform. SSSPAM simulations with: (i) active weathering and (ii) without weathering were run for each material. The erosion rate and the overall landform structure were then compared between weathering and non-weathering simulations.

Aug 2, 2023

By Donald M. Ulbrich

Any of you who served in the military remember the admoniton to "get the lead out," In the military environment, where cost wasn't always a factor, "get the lead out" was more often a call for activity of any sort than activity of a particularly productive nature. As a result, when the top sergeant yelled "get the lead out," lots of people started moving.. . usually to get out of his way. Now there's a new cry, ..one that comes not only from the military but from an entire nation threatened with dependence on foreign sources for its energy needs. That cry ...get the coal out, Like the earlier order, it's a call to activity. A signal that the coal reserves of the United States must be tapped so that Project Independence can succeed by 1985, But it's more than a mere call to activity; it's also a call to achieve productivity. ,a call to produce coal both efficiently and acceptably. And that leads us to the key questions of where the coal is going to come from to meet that 1985 goal, and how can it best be mined. Where will the coal come from? There's no doubt much of it must come from surface mining in the West. How can this coal be mined? There are several options available but there is an excellent case to be made for using mining shovels and haul trucks due to their versatility in stripping, loading and reclamation, We'll explore this approach in this talk today.

Jan 1, 1976

By Isabel Lázaro

A detailed study has been undertaken into the electrochemistry of the leaching of chalcopyrite in acidic solutions containing ferric ions. Mixed potential measurements have shown that the maximum potential achievable on a chalcopyrite disk in a ferric sulfate medium lies within the so-called passive or prewave region in the anodic behavior of chalcopyrite. The very low current densities due to the anodic oxidation of chalcopyrite at potentials in the region of the mixed potential has made studies of the initial stages of dissolution difficult. However a careful rotating ring-disk electrode (RRDE) study has enabled data to be obtained for the stoichiometry of the initial dissolution reaction to be obtained. Thus, in addition to the detection of soluble iron and copper as products in this potential region, a soluble sulfur species has also been detected. A comparison of the experimental with the expected collection efficiencies of the products on the ring has revealed that this soluble sulfur species is likely to be thiosulfate. The characteristic transient anodic behaviour of chalcopyrite in this potential region has been interpreted in terms of a rate limiting solid-state diffusion process. Thus, extrapolated rates based on reported measured solid-state diffusion coefficients for the mineral at elevated temperatures have been shown to be consistent with the potentiostatic current-time transients. Furthermore, comparative studies of the anodic characteristics of the copper sulfide minerals covellite and bornite has confirmed their greater reactivity in this potential region. The results of this investigation have been combined with a parallel study of the non-oxidative behaviour of chalcopyrite in order to derive a model for the dissolution process which is consistent with other published studies of the electrochemistry and dissolution of the mineral.

Jan 1, 2003

The following notes have been compiled to assist authors in the preparation of papers for presentation to the Institute and for publication in the Journal. All papers must meet the standards set by the Council of the Institute, and for this purpose all papers are referred to at least two referees appointed by Council. STANDARDS FOR ACCEPTANCE To merit consideration papers should conform to the high standards which have been established for publication over many years. Papers on research should contain matter that is new, interpretations that are novel or of new significance and conclusions that cast a fresh light on old ideas. Descriptive papers should not be a repetition of well-known practices or ideas but should incorporate developments which would be of real interest to technical men and of benefit to the mining and metallurgical Industry. In some cases a well prepared review paper can be of value, and will be considered for publication. All papers and particularly research papers, no matter how technical the subject, should be written with the average reader of the Journal in mind, to ensure wide interest. The amount of textbook material included in a contribution should be the minimum essential to the argument. The length of a paper is not the criterion of its worth and it should be as brief and concise as possible, consistent with the lucid presentation of the subject. Only in very exceptional circumstances should a paper exceed 15 pages of the Journal (15 000 words, if there are no tables or diagrams). Six to ten pages is more normal. NOTE: Papers in the Journal are printed in 10 point type, which is larger than the 8 point type used on this page. For special publication Council may decide on page sizes smaller than A4 used for this Journal. The text should be typewritten, double-spaced, on one side only on A4 size paper, leaving a left-hand margin of 4 cm, and should be submitted in duplicate to facilitate the work of the referees and editors. Orthodox sequence Title and author's name, with author's degrees, titles, position. Synopsis. Index, only if paper is long and involved. Introduction, including a brief statement of conclusion. Development of the main substance. Conclusions, in more detail. Acknowledgements. References. Title: This should be as brief as possible, yet give a good idea of the subject and character of the paper. Style: Writing should conform to certain prescribed standards. The Institute is guided in its requirements by: Collins, F. H., Authors & Printers' Dictionary-Oxford University Press. Hart, H. Rules for Compositors and Readers. Humphrey Milford (familiarly known as the Oxford Rules). Fowler, H. W. & F. G. The King's English-Oxford University Press. General: A few well selected diagrams and illustrations are often more pertinent that an amorphous mass of text. Over-statement and dogmatism are jarring and have no place in technical writing. Avoid the use of the first person, be objective and do not include irrelevant or extraneous matter. Avoid unnecessary use of capitals and hyphens, while punctuation should be used sparingly and be governed by the needs of sense and diction. Sentences should be short, uninvolved and unambiguous. Paragraphs should also be short and serve to separate basic ideas into compact groups. Quotation marks should be of the 'single' type for quotations and "double" for quoted matter within quotations. Interpretations in the text should be marked off by parentheses ( ), whereas brackets [ ] are employed to enclose explanatory matter in the text. Words to be printed in italics should be underlined singly. For small capitals they are to be underlined DOUBLY and for large capitals TREBLY. Abbreviations and symbols are laid down in British Standard 1991. Abbreviations are the same for the singular and plural, e.g. cm for centimetre and centimetres, kg for kilogram and kilograms. Percentages are written in the text as per cent; the symbol % is restricted to tables. A full stop after an abbreviation is only used if there is likely to be confusion of meaning. Metric System: The Systemé International d'Unites (S.I.) is to be used for expressing quantities. This is a coherent system of metric units derived from six basic units (metre, kilogramme, second, ampere, kelvin, and candela), from which are derived all other units, e.g. the unit of force is the newton (N) for kilogramme metre per second per second (kg m/s2). Always use the standard metric abbreviations. Commas must not be used for separating groups of digits. For ease of reading digits should be grouped in threes counting from the decimal point towards the left and the right. Illustrations: Drawings and diagrams are to be in black India ink and should be about 18 cm wide. When submitting graphical representations avoid a fine grid if possible. Curves should be in heavy line to stand out. Lettering too should be bold as a reduction in size is often involved in the printing process. (A single column is 8.5 cm wide.) Numbering of tables should be in Roman numerals: I, 11, etc. and figures in Arabic numerals: Fig. 1, Fig. 2, etc. (Always use the abbreviation for figure.) Photographs should be black and white glossy prints. As a guide to the printer the author should indicate by means of notes in the typescript where tables and figures, etc. are to appear in the text. Paragraphs: A decimal system of numbering paragraphs may be used when the paper is long and complicated and there is a need for frequent reference to other parts of the paper. Proof correction: Galley proofs are sent to authors for the correction of printers' errors and not for the purpose of making alterations and additions which may be expensive. Should an author make alterations which are considered excessive, he may be required to pay for them. Standard symbols as laid down in British Standard 1219C should be used. SYNOPSIS It is most important that the synopsis should provide a clear outline of the contents of the paper, the results obtained and the author's conclusions. It should be written concisely and in normal rather than abbreviated English and should not exceed 250 words. While the emphasis is on brevity this should not be laboured to the extent of leaving out important matter or impairing intelligibility. Summaries simplify the task of abstractors and therefore should present a balanced and complete picture. It is preferable to use standard rather than proprietary terms. FOOTNOTES AND REFERENCES Footnotes should be used only when they are indispensable. In the typescript they should appear immediately below the line to which they refer and not at the foot of the page. References should be indicated by super-script, thus. . .1 . . .2. Do not use the word Bibliography. When authors cite publications of other societies or technical and trade journals, titles should be abbreviated in accordance with the standards adopted by this Journal. GENERAL The Council will consider the publication of technical notes taking up to three pages (maximum 3 000 words). Written contributions are invited to the discussion of all papers published in the Journal. The editors, however, are empowered by the Council to edit all contributions. Once a paper or a note has been submitted to the Institute, that document becomes the property of the Institute, which then holds the copyright when it is published. The Institute as a body is, however, not responsible for the statements made or opinions expressed in any of its publications. Reproduction from the Journal is permitted provided there is full acknowledgement of the source. These points should be borne in mind by authors who may submit their work to other organisations as well as to the Institute.

By F. D. Mahone

Much crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in globules sufficiently large to settle out, in time, if the fluid is allowed to stand, or as an emulsion formed by myriads of minute water particles, each surrounded and entrapped by a film of oil through which it cannot break under the action of gravity alone. Such an emulsified mixture of oil and water is commonly termed "cut oil." When such an emulsion is subjected, under proper conditions, to the influence of a high-potential alternating-current field, the minute water particles rupture the enveloping oil films and coalesce into larger water droplets this procedure continuing until all the water is freed into drops of such size that they readily settle out. This action has been photographed by the micro-moving-picture camera; under the microscope, the breaking-up of the emulsion, as described, is seen to be accomplished in a few seconds. The low power requirements of the process, from records of commercial plants, substantiate the theory that the action is that of a multitude of electrical condensers in series, rather than that of a number of conducting paths. The minute water particles serve as the metallic elements, or plates, of the condensers and the separating oil acts as the dielectric. Such surface charges as the particles may have are removed, and the intervening oil is broken, probably electrically by the voltage and mechanically by the attractive force between adjacent oppositely electrified particles. The principle of breaking up an emulsion under the influence of an alternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resulted in a plant being installed on the property of the Lucile Oil Co. in the Coalinga field, California, early in 1909. This plant was able to reduce 14-per cent. emulsion to less than Pper cent. with commercial success. Standard Cottrell Apparatus The present standard Cottrell apparatus consists essentially of the electric treater and a settling or trap tank. The treater is a galvanized-iron tank approximately 3 ft. in diameter and 10 ft. high, which con-

Jan 1, 1924

By Charles E. Glass

A steadily growing body of evidence indicates that earthquake ground motions can cause failure of rock slopes that are otherwise stable under static loading conditions. As a result, the economic optimum working slope angle is reduced when earthquake shaking is considered in surface mine design, especially in regions of high seismicity. When designing surface mine slopes to withstand seismic motion it is as important to consider the probability of experiencing various levels of ground shaking as it is to consider the characteristics of the ground motion. For most slope designs, simple probabilistic techniques such as extreme value or maximum likelihood techniques are appropriate. These techniques, however, should be applied in such a way that a probability value is assigned to characteristic ground motion parameters at the mine rather than to nearby earthquake magnitudes. Several techniques have been developed to analyze rock slopes subjected to dynamic loads. Most of these techniques do not adequately account for the ground motion parameters of concern. The best technique appears to be one that utilizes actual earthquake time histories. A simple technique that calculates block displacement for any input accelerogram, using a linear acceleration approximation between time steps, has been developed that accurately accounts for rock block response. Results using this technique indicate that the following factors are important for assessing rock slope stability in earthquake regions:

Jan 1, 1983

By R R. Lovel

In this paper, life cycle assessment methodology has been used to assess the variations in water use associated with different metal production and processing routes and provide insights into the value derived from water usage in the minerals sector. Using water consumption data derived from the literature it has been shown that the æcradle-to-gateÆ water consumption (or embodied water) for production of the various metals considered in the study ranged from 2.9 m3/t for steel up to 252 087 m3/t for gold. The results largely reflect the grade of the initial ore used to produce each metal, and can be approximated by the following equation: W = 167.7 G - 0.9039 where: W = embodied water (m3/t refined metal) G = grade of ore used to produce metal (per cent metal) The study showed that indirect water consumption in the metal production life cycle, in particular that due to electricity generation, can make a significant contribution to the embodied water value, eg aluminium production. When expressed in terms of m3/t ore, the results for all metals considered indicated that the embodied water is roughly, on average, three times the water consumption of the mining and concentration stage. It was also shown that the economic value per m3 of water consumed for the minerals industry exceeds that for the agricultural and industrial sectors, supporting the view that allocating water resources to the minerals industry has a strong underlying economic basis. Water reforms currently taking place in Australia aim to address issues such as competition for water access, reduced security of supply and increase in cost. Consequently the minerals industry, along with others, can be expected to come under increasing pressure to reduce fresh or raw water use and to integrate water use across sectors. While water recycling is an obvious candidate to help reduce water consumption in the minerals industry, issues such as water quality, among others, will influence the extent to which this can be achieved. In addition, wastewater volumes can be minimised using techniques such as pinch analysis to establish and use the minimum water requirement for the process. The use of dry or near-dry processing technologies, for which the demand for water is small or zero, may be a more radical solution to the water consumption problem; however, it is possible that the introduction of dry processing would bring with it a new set of problems, including dust.

Jan 1, 2006

By Glenn A. Marsh, George Bernard

It is often assumed that aerated oil field brines which are to be injected underground contain dissolved oxygen in amounts which will cause appreciable corrosion. Through the use of a new portable dissolved oxygen meter, accurate determinations were made at three brine conditioning plants. At two older plants, dissolved oxygen concentration in the final treated brine was found to he almost zero In spite of aeration during the conditioning process. At a new plant, dissolved oxygen was initially present but disappeared soon after the brine was "inoculated" with oxygen-free brine from one of the other plants. Corrosion tests at the two older plants have substantiated predictions that the brines would lint be corrosive. These results show that mechanical deaeration may not always be required in brine treating plants. INTRODUCTION The present work was undertaken to add to our knowledge of aeration and deaeration of oil field brines in brine conditioning plants. It is commonly assumed that brines which are exposed to the air soon become more or less saturated with dissolved oxygen. Since oxygen-containing brines are known to be corrosive, precautions are often taken to keep air out of brine through the use of closed systems or mechanical deaeration. The study of oxygen in brine has been seriously hampered in the past because of the lack of a suitable analytical tool. The standard Winkler method for the determination of dis-solved oxygen is satisfactory for use in fresh water, but not in many oil field brines. Corrections have to be made for a number of reducing substances such as ferrous iron and hydrogen sulfide which are commonly present in natural brines. Very often the correction factors are much greater in magnitude than the amounts of oxygen which are to be determined, and consequently erroneous results are obtained. Also. erratic Winkler data are obtained when appreciable concentrations of calcium and magnesium salts are present. The first step in carrying out a systematic study involved designing a portable dissolved oxygen apparatus which would operate in natural brines. Subsequently, this apparatus was used in three brine conditioning plants. Dissolved oxygen data obtained here, and certain corrosion rate data, illustrate the interesting behavior of oxygen in these oil field brines. APPARATUS A portable dissolved oxygen meter described in detail elsewhere,' was developed specifically for use with oil field brines. It is a polarographic apparatus employing a small rotating platinum electrode (cathode) and calomel reference electrode (anode). A potential of 0.7 volts is applied across the electrodes while they are immersed in the brine to be tested. 4References given at end of paper.

Jan 1, 1952

By Robert Hopler

RBH Note: in 1913 black powder was still dominant as a coal-mining explosive, but permissible explosives were making some slight headway. For example, in 1902 there were only 11,300 pounds of permissibles used in coal mining, but in 1913 the quantity was 21,801,285 pounds. However, there were 187,551,653 pounds of black powder used that year. It took many years before the use of black powder ended in coal mining. From the picture of the miner reparing his explosives it’s hard to tell what he’s using, but the fact that a wooden Du Pont powder box is shown, he’s probably not using black powder. That doesn’t mean he’s using a permissible, either, since that was not yet a requirement. It’s interesting that the miners have open flame cap lamps, and the miner is actually smoking a pipe while preparing his explosives.

Jan 1, 2014

By S. J. Page, W. E. Wallace, P. Bolsaitis, D. Eppelsheimer, M. J. Keane, J. Poston, J. Harrison

"Respirable-sized dust particles from a clay mine and mill were examined for aluminium and silicon content by scanning electron microscopy-energy dispersive X-ray analysis at incident electron energies of 5--20 keV. Most of the high silica content particles, those which had a silicon to silicon plus aluminium signal fraction, measured at 20 ke V, of0.9 or greater, showed a decrease in the silicon fraction of signal with decreasing incident electron energy, down to values of between 0.6 and 0,8 at 5 keV: this decrease was a function of particle size and composition. Simple models for silicon fractiol) of signal vs incident electron voltage suggest this behavour is due to a heterogeneous particle structure in which an aluminosilicate coating occludes the surface of a silica particle core. The coating survives incubation in a major component of pulmonary surfactant.INTRODUCTIONMINING and some other dusty workplace atmospheres are monitored for respirable dust and quartz dust for purposes of occupational health protection, respirable quartz dust being a known cause of pulmonary disease. Respirable quartz exposure data are acquired also for epidemiological research on the correlation of pulmonary disease prevalence with respirable dust composition and concentration. For these purposes quartz content often is measured on collected dust samples by X-ray diffraction or in spectroscopy. Scanning electron microscopy-energy dispersive X-ray analysis spectrometry (SEM-EDX) is also used. The first two methods measure the bulk composition of a multi-particle dust sample; SEM-EDX measures the elemental composition of single ·particles. These methods as typically applied, including SEM-EDX with a 20-30 kilo-electron volt (keV) electron beam accelerating potential, do not distinguish homogeneous distribution of impurities in a particle from possible heterogeneous surface distribution. These measurements of quartz content are not always accurate predictors of the prevalence of dust-induced disease (ROBOCK and BAUER, 1990), which implies that the biologically available quartz surface may not be equivalent to conventionally measured quartz content of respirable dust in some exposure settings. Using a minor modification of conventional scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) protocols on samples of settled and airborne dust from a clay mine and mill we have detected heterogeneity with depth for aluminium impurity in high silica content particles, indicating that some of the quartz or 'free silica' respirable particles of the dust are aluminosilicate occluded. Coatings were not removed by incubation of the dust in a surrogate pulmonary hypophase surfactant fluid."

Jan 1, 1990

By Joao Felipe Costa, Jair C. Koppe, Andre Zingano, Cleber Gomes

"Run-of-mine Brazilian coal has high ash content and low calorific power. Therefore, the coal must be washed to achieve the power plant specifications for burning coal. A large amount of waste results from the coal preparation, and it must be disposed of in waste piles or waste dams, depending on the material size. These waste disposals are the cause of serious environmental problems, not only in the short and medium terms, but mainly in the long term, due to the risk of provoking acid drainage or spontaneous combustion. Waste disposal requirements also demand large areas. Other problems include the pillar and roof stability in abandoned and mined out areas, building of edifices on the old and active mines, and mining under urban areas. To solve these problems simultaneously, backfilling the entries in mined out areas began with two objectives: to understand the mechanical behavior of the filling material and to model the backfilling of room-and-pillar coal mine entries through numerical simulation. Laboratory tests were performed for different filling material (with and without cement) to determine its mechanical properties and failure criteria. Based on this study, it was possible to conclude that the backfill method is a good strategy to improve the ground stability in room-and-pillar coal mines for the long term, especially for weak coal seams, and to reduce the quantity of material on waste piles on the surface.INTRODUCTIONRun-of-mine (ROM) Brazilian coal has high ash content and low calorific power. Therefore, the coal must be washed to achieve the power plant specifications for burning coal. Two types of waste are associated with power plants that bum coal for energy generation: 1) the waste from the coal preparation plant and 2) the ash from the power plant after coal burning.The Brazilian coal ash content in the ROM coal is between 45 and 55%. The clean coal is 20 to 30% ash for 4,500 kcal/kg (18,000 BTU). The coal preparation plant recovery is only about 35%. Santa Catarina State (SC) produces about 7 million tons/year of ROM coal, which results in a total of 4.5 million tons of waste. This is a large amount of waste that must be disposed of in waste piles or waste dams, depending on the material size. The waste and ash content is represented by silicate materials, such as clay and sand, and by sulfide materials, like pyrite and organic sulfur (between 1and5%)."

Jan 1, 2010

By W. H. Ode, W. A. Selvig

In 1938 , the Bureau of Mines cooperated with Subcommittee XV on Plasticity and Swelling of Coal ( C. C. Russell , chairman ) , of Committee D-5 on Coal and Coke , A.S.T.M. , by testing various methods for determining expansion and plastic properties of a series of coals of widely different coking properties . One of the tests made by the Bureau was the British Standard Method for the Crucible Swelling Test for Coal.5/ Briefly , this swelling test consists in heating 1 gram of pulverized coal in a silica crucible over a gas flame under prescribed conditions to form a coke button which is compared in size and shape with a series of standard profiles numbered 1 to 9. These profiles are intended to cover the size and shape of buttons obtained from coals covering a wide range in plastic properties .. The number of the standard profile with which the maximum cross -sectional area of the button most nearly corresponds is recorded as the swelling index . Although the swelling test showed poor relationships with the various tests that were used for measuring expansion or contraction of coal during carbonization , it gave indications of having value in measuring free - swelling and caking properties of coals when burned on fuel beds . An opportunity to investigate this occurred when an engineer of an eastern public utility 'company reported pronounced differences in burning characteristics on grates of various shipments of Pocahontas coal . Some of these coals gave trouble by swelling 'excessively and clogging the grates . Samples were ob- · tained , and it was found that the troublesome coals gave decidedly higher free -swelling numbers than did the coals that performed satisfactorily . Also , it was found that the free - swelling index test gave better differentiation between coals than could be obtained from the coke buttons from the · ´`standard volatile -matter test or from agglutinating - value results . The results of the free - swelling tests were considered by the Subcommittee on Plasticity and Swelling , and a special group of the subcommittee , under the chairmanship of R. A. Sherman , was delegated to study the test method . Ostborg , Limbacher , and Sherman , ofthe Battelle Memorial Institute , ' investigated the various factors affecting the test and found that the swelling index was a good indication of the suitability of coal for performance on residential -type stokers from the standpoint of the coking characteristics of the coal . Data were presented also showing that the indexes wer helpful in the selection of coal for industrial underfeed stokers .

Oct 1, 1946

By A. Hultgren, B. Herrlander

The original aim of the present investigation was to study the mechanism of cracking on hot-deforming red-short steels. During the microscopical examination of hot-deformed soft steels attention was directed to various patterns of so-called veining in the ferrite, as related to variations in the deformation procedure and the heat-treatment of the steels. Later, a hot-short steel of higher carbon content was also studied. Historical Storey1 suggested in 1914 that veining developed during the gamma-alpha transformation from the growing together of several alpha nuclei within the same gamma grain. Rawdon and Berglund2 found that in soft steel, forged somewhat below A3, the ferrite showed profuse veining, while usually there was very little veining after forging at very high temperatures. They emphasized the similarity between the pattern of veining formed by deformation about 600°C and that of slip lines formed by deformation at room temperature. They also suggested a relation between the gamma-alpha transformation and veining. They became convinced from etching and from the slip-line pattern in cold-deformed material, that the orientation within any ferrite grain showing veining was uniform. In recrystallized alpha grains veining was absent. Veining did not appear materially to affect the properties of ferrite. Independent of veining, continuous networks, attributed to preexisting delta and gamma grain boundaries were sometimes found, the former only in cast steel. Those networks were usually connected with small inclusions. Ammermann and Kornfeld3 confirmed that recrystallized ferrite grains showed no veining. In soft steel annealed between A1 and A3 there was veining only in the ferrite grains formed during cooling. Electrolytic iron deformed at 880' was free from veining. Bannister and Jones' considered veining in ferrite to be a manifestation of microscopical and sub-microscopica~ inclusions. NorthCOtt,5,6 in studies on veining in steel and other metals and alloys, attributed veining to oxide inclusions. It could generally be removed by annealing in hydrogen, a suggestion earlier made by Rawdon and Berg1und. TrittOn (discussion in ref. 5) emphasized the importance of perfect polishing for bringing out veining by etching, and thought the veins or subboundaries were produced during the gamma-alpha transformation, when it was rapid, as a result of the volume change and contraction during cooling. Slight distortion would not allow projecting parts of a growing crystal to join up with atomic symmetry. Hanemann and co-workers showed that veining in ferrite consisted of ridges

Jan 1, 1948

By B. Herrlander, A. Hultgren

The original aim of the present investigation was to study the mechanism of cracking on hot-deforming red-short steels. During the microscopical examination of hot-deformed soft steels attention was directed to various patterns of so-called veining in the ferrite, as related to variations in the deformation procedure and the heat-treatment of the steels. Later, a hot-short steel of higher carbon content was also studied. Historical Storey1 suggested in 1914 that veining developed during the gamma-alpha transformation from the growing together of several alpha nuclei within the same gamma grain. Rawdon and Berglund2 found that in soft steel, forged somewhat below A3, the ferrite showed profuse veining, while usually there was very little veining after forging at very high temperatures. They emphasized the similarity between the pattern of veining formed by deformation about 600°C and that of slip lines formed by deformation at room temperature. They also suggested a relation between the gamma-alpha transformation and veining. They became convinced from etching and from the slip-line pattern in cold-deformed material, that the orientation within any ferrite grain showing veining was uniform. In recrystallized alpha grains veining was absent. Veining did not appear materially to affect the properties of ferrite. Independent of veining, continuous networks, attributed to preexisting delta and gamma grain boundaries were sometimes found, the former only in cast steel. Those networks were usually connected with small inclusions. Ammermann and Kornfeld3 confirmed that recrystallized ferrite grains showed no veining. In soft steel annealed between A1 and A3 there was veining only in the ferrite grains formed during cooling. Electrolytic iron deformed at 880' was free from veining. Bannister and Jones' considered veining in ferrite to be a manifestation of microscopical and sub-microscopica~ inclusions. NorthCOtt,5,6 in studies on veining in steel and other metals and alloys, attributed veining to oxide inclusions. It could generally be removed by annealing in hydrogen, a suggestion earlier made by Rawdon and Berg1und. TrittOn (discussion in ref. 5) emphasized the importance of perfect polishing for bringing out veining by etching, and thought the veins or subboundaries were produced during the gamma-alpha transformation, when it was rapid, as a result of the volume change and contraction during cooling. Slight distortion would not allow projecting parts of a growing crystal to join up with atomic symmetry. Hanemann and co-workers showed that veining in ferrite consisted of ridges

Jan 1, 1948