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By Frank H. Skelding

A new, large mine is about to be born. Many years and millions of dollars have been invested in exploration. An orebody has been found and proven. All necessary political and legal work to establish rights and conditions for development are complete. The feasibility studies are favorable. Financing has been arranged. Board approval has been given to proceed. The time has come to engage a contractor to design and build the new facilities in a location, as is the common case today, far re¬moved from the centers of advanced technologic development where the minerals will ultimately be used. A select list of Engineering and Construction (E&C) companies is asked to prepare proposals. At this point the common viewpoint among mining companies is that the company's sole remaining problem, a major one to be sure, is to select qualified contractors to design and build the project at the lowest cost and shortest time possible so that production can start generating a return on investment. The purpose of this discussion is to explore the viewpoint of the large E&C contractor toward such projects. It differs in important ways from that of the client mining company and it is these differences and the reasons for them that must be understood by the client if severe difficulties and misunderstandings with the contractor, starting at the beginning of contract negotiation and continuing through design and construction to final startup are to be avoided or minimized. Often enough, the difference is in degree, not kind, which only serves to obscure the fact that a difference exists.

Jan 1, 1975

By V. Panayotov, M. Panayotova

"The combined use of semiconductor properties and specific flotation characteristics of minerals under different conditions with external influences ensures a possibility for process control and management. This work presents the relations between the volumetric and surface characteristics of minerals and the minerals' flotation ability (flotability), as well as the possibility for the flotability purposeful change. Results from proprietary laboratory and industrial research are presented showing how controlled impacts on minerals and flotation pulp improve flotation technology. Such an approach reveals prospects for the creation of new technologies for the minerals' beneficiation.INTRODUCTIONThe decrease of the useful components content in the ores, the increasingly complex nature of the raw materials, the increasing energy consumption per the unit of production, and the need to solve the problems related to the environment pollution require solutions different than the existing classical ones. One of the ways to find such solutions is the detailed consideration of the fundamental properties of minerals and, in particular, of minerals having semiconductor properties. The studies of Plaksin et al. (1968), Chanturia and Shafeev (1977), Chanturia and Vigdergauz (2008), Carta et al. (1973), Hoberg and Shneider (1975), Rao et al. (1992) have given an idea of the energy state of the minerals, their flotation ability, and the ways in which this ability can be changed in one or the other direction. The main line in these works is the study and use of the relationship between bulk and flotation properties of minerals. To improve the efficiency of the process, it is also necessary to consider the relationship between the surface properties of the minerals, especially minerals-semiconductors, and their flotation ability.THEORETICAL BACKGROUND IN BRIEFA quantitative estimation of energy changes in a solid phase in the process of flotation may be made by taking in account the changes in the Fermi level. Its position in the forbidden band is an indicator about the direction and the intensity of electron exchange between solid and liquid phases. The Fermi level energy EF enables the estimation of flotability, intensity of needed external impact before flotation, as well as efficiency of the process going on. Quantitative estimation of these processes can be made by means of the flotability coefficient Kf."

Jan 1, 2018

By J. E. Gould, H. J. Hand

MANY independent studies are being made on slag-metal relationships in the open-hearth furnace, and these studies cannot help but result in an ultimate improvement in the quality of open-hearth steel of both the open and killed types In maintaining quality control at the National Tube Company's plant, emphasis has been placed on an evaluation of the iron oxide content of the steel in as quantitative a manner as possible, in order that the most desirable level of oxidation might be obtained for a given type of steel, and to secure a more precise basis for final deoxidation In the past, various methods were used for estimating FeO content of the metal at tap to ensure uniform and thorough deoxidation of killed steel, avoiding over-deoxidation to minimize the amount of inclusions present and to make as sound a steel as possible For the open-type steels, such control involves obtaining the necessary level of oxidation for the most suitable action of the steel in the molds to provide good surface quality and cross section for the specific grade involved While rapid analytical methods are available for determination of FeO in the liquid metal, such methods are still not sufficiently rapid for routine control on the open-hearth floor, nor do such analyses provide information as to what causes high or long FeO values The method of sampling can still be considered a problem in view of the variability encountered in taking simultaneous duplicate tests With the accurate rapid methods now available for determining carbon in the metal, estimating slag basicity and obtaining temperatures of liquid metal, it was believed possible to determine the influence of the various furnace reactions in establishing the state of oxidation at a given time Simultaneous slag and metal tests were used in this analysis, aided by statistical methods, to determine the factors that affect the metal FeO, and also to make a quantitative evaluation of these factors Data obtained are from actual furnace operations, the metal test being of the spoon, Herty type, and taken in duplicate. Metal temperatures were taken with the open-tube bath pyrometer developed by the Research Laboratory of the United States Steel Corporation This method of taking open-hearth metal temperature was invented by Collins and Oseland,1 and was developed into its present form by L 0 Sordahl,2 of the Research Laboratory The instrument and its mode of operation have been fully described by Sordahl and Sosman in three publications 3,4,5 Slag components were obtained by chemical analysis Data were taken from four 165-net-ton furnaces during the working period of the heat Recognizing that additions of ore affect the

Jan 1, 1942

By Werner Hofmann

INTRODUCTION The attempt to interprete lung cancer incidence caused by inhaled radon decay products in items of radiation dose raises the question of the relevant dose. The various dosimetric approaches published by now are characterized by an increasing complexity in the structure of the models used. Ranging from organ doses to microdosimetric specific energy distributions in the cells at risk, a significant trend from the macroscopic to the microscopic scale can be observed. Since tumors originate preferentially in the basal cells of the lobar and segmental bronchial epithelium, these cells are regarded as the critical target for inhalation carcinogenesis. The evaluation of basal cell doses is, therefore, the main objective of lung dose assessments. Various dosimetric models have been published in the past (Altshuler, Nelson and Kuschner, 1964; Haque and Collinson, 1967; Harley and Pasternack, 1972; Hofmann, Steinhäusler and Pohl, 1979, 1980; Jacobi, 1964; Jacobi and Eisfeld, 1980; James , Greenhalge and Birchall, 1980). Due to incertainties of physical and biological parameters involved and the application of different anatomical and physiological models the claculated doses are varying up to one order of mangitude. Independent of the choice of these dosimetric models applied to the calculation of lung doses, deposition, clearance and resulting dose are affected essentially by the properties of the inhaled aerosol as well as by personal characteristics. Both the properties of the exposed individual as well as of the inhaled environmental atmosphere have to be considered in radiation protection. It is the main objective of this paper to illustrate the influence of both parameter sets on basal cell doses by varying the above parameters. PERSONAL CHARACTERISTICS Though it might be more convenient for radiation protection calculations, the biological "man" cannot be represented by a uniform standard man. In Tab. 1 these personal characteristics which cause the variability of man are listed together with the region of their effectiveness. In the following the influence of these parameters will be discussed with regard to lung dose assessments. Besides these factors the great biological variability of all anatomical and physiological parameters involved as well as pathological alterations due to lung diseases cause additional variations in lung dosimetry. [ ] Age Age can be considered as the most important personal factor influencing the anatomical structure of the lung between birth and about 15 years of life. This period is characterized not only by an enlargement of already existing respiratory units but also by structural changes. Besides these anatomical alterations deposition is strongly dependent also on respiration parameters, such as tidal volume (TV) and respiratory frequency (RF). Whereas RF decreases with progressing age in an exponential manner, TV increases significantly resulting finally in a growth of the respiratory minute volume (RMV). Also mucus clearance in the infant might be more effective than in the adult, though no reliable experimental data are available. Superposing all these age-dependent changes mean basal cell doses are higher for children by about a factor of 2 than for adults living in the same radioactive environment (Hofmann, 1981). In the adult the following alterations of respiration standards with age are reported: total lung capacity diminishes with age, functional residual capacity is unchanged or increases with age and the dead space rises slightly with age (ICRP, 1975). The influence of these lung capacities on deposition, however, can be regarded as insignificant. Due to the ageing process mucus velocities my be considerably smaller in older people. This effect can also be superposed by the simultaneous influence of ciliatoxic effects of cigarette smoke and air pollutants or other bronchial diseases. Since the lower age limit for occupational exposure is about 18 years, age can be disregarded in the uranium mining industry for the determination of radiation doses, though lung cancer induction is significantly dependent on age.

Jan 1, 1981

By M. Drozd, M. Somppi, Z. Yamak

"Granular activated carbon is widely used in the gold mining industry for gold extraction from aurocyanide-containing slurry. The extraction process can employ carbon as part of the gold recovery operation for various circuit designs including carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) circuits. However, various qualities of activated carbon exist and the durability of the material can change significantly from source to source. Handling this expensive reagent can pose challenges when fine carbon losses occur in the CIP, CIC, and CIL circuits. Additionally, any gold that is adsorbed to these carbon fines can also be lost by various mechanisms including carbon attrition and fracturing, inefficient coarse-fine separation, and poor carbon fines capture. With the above in mind, a series of tests were conducted to investigate standardizing simple laboratory methods for testing carbon quality. A standard procedure beyond or enhancing ASTM methods can serve as additional starting points for evaluating carbon specific to the gold industry. The investigation focused on size distribution, flatness, wet attrition resistance, surface area, gold kinetics, and gold loading. The final results provided information to generate an equation for ranking carbon samples to plant performance.IntroductionActivated carbon for use in gold extraction is amongst the most commonly found processes in modern gold-milling plants. Although gold losses are inevitable in the milling process, operators often focus on the importance of maximizing gold recovery. One focus area that is important in gold recovery is optimizing the use of activated carbon and examining potential changes to realize improved economics for carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) processes."

Jan 1, 2017

By Yap Chu-Phay

IN 1923, when the writer began his studies in metallurgy, he came upon an article by Professor Honda on the, Equilibrium Diagram of the Iron-carbon System, 1 which made a profound impression on him. What interested him most was this sentence: "In the recent diagram of the iron-carbon system, the solidus is usually shown as a curve bending considerably downward. But it can be shown by thermodynamics that if the liquidus is straight or slightly curved, the same must also be true for the solidus. Hence, in my constitutional diagram, the lower portion of the solidus is slightly bent upward." Ever since then the writer has been interested in thermodynamics, especially chemical thermodynamics. The applications of thermo-dynamics to the metallic systems have been, in the writer's opinion, sadly neglected, although we continually use the phase rule in our study of equilibria in the liquid and solid states of metallic alloys. Many investigators, among whom may be mentioned Heycock and Neville, and s Honda and his coworkers, have applied the simple Raoult-van't Hoff law of depression of freezing point, mainly to determine the heat of fusion, but no attempt has been made to investigate the applicability of the thermo-dynamic laws of solution (as opposed to the laws of solution derived from other sources) to metallic systems" showing either limited or complete solid solutions. Perhaps the reason for this neglect is that until recently there have been so few reliable data on the solidus, which is much more difficult to determine than the liquidus. The writer has under way at the present time an investigation of a number of systems, the solidi of which have been more or less reliably determined. Recently, the writer has not only shown the valid applicability of the thermodynamic laws of solution as applied to the system antimony-bismuth but has also suggested a method of attacking problems involving complete and incomplete equilibria.2 In the present paper, the same method of approach is employed. For convenience, we shall divide this paper into two parts:

Jan 1, 1931

By Paykan Safe

?? Background ?? WorleyParsons Gas Cleaning ?? PT Inco Smelter ?? Process Design Considerations ?? Furnace Control and Combustion ?? Combustion Chamber ?? Spray Chamber ?? Draft Control ?? Baghouse ?? Secondary Ventilation ?? ID Fan ?? Dust Handling Equipment ?? Project Execution ?? Heat Recovery ?? Conclusion ?? WorleyParsons Gas Cleaning ? Irving, TX ?? Formerly Gas Cleaning Technologies ?? Acquired by WorleyParsons in 2005 and now part of a global EPCM company ?? 14 years experience in off-gas system design for ferrous and non-ferrous facilities worldwide

May 1, 2008

By Fullagar P. K

In resource definition and mine development, major capital expenditures are committed on the basis of sparse information and even in production surprises such as bad ground are not uncommon. Drill holes constitute the principal source of information about the orebody and its environment and optimisation of drilling implies maximising the yield of useful information per dollar expended. Geophysical borehole logging provides new flexibility for optimising the drilling budget. Economic benefits can flow from geophysical logging at all stages of the mining cycle. The most commonly cited benefit is substitution of diamond delineation drilling with cheaper percussion or reverse circulation drilling in cases where geophysical logs can substitute for core. This approach can deliver an attractive direct saving in drilling costs (and time) if drill meterage is unchanged, or a potentially greater indirect benefit from better ore control if more holes are drilled within the original drilling budget. More ore contact intercepts per dollar can translate into lower dilution and enhanced ore recovery, thereby increasing revenue as well as reducing mining costs. Substitution of diamond drilling with percussion drilling is not always feasible. However, geophysical logging of diamond holes is often highly advantageous in its own right, both for geotechnical characterisation as well as ore delineation. Operational advantages of logging include data objectivity, speed of interpretation and reduced core handling and analysis costs. Geophysical logging assists mining engineers by providing a continuous measure of in situ rock strength, even over intervals with poor core recovery. The additional expense of geophysical logging in blast holes can be justified in terms of more accurate ore boundary delineation and rock strength evaluation. Precise ore boundary delineation permits refinement of charge placement, to minimise dilution and maximise recovery. Detailed knowledge of rock strength can enable optimisation of blast design. Rock strength can be evaluated in real-time via analysis of drill performance data recorded with measurement-while-drilling (MWD) technology. To successfully apply geophysical logging in mines, its technical, operational and economic viability must all be established. This entails verification of the existence of appropriate physical property contrasts, investigation of the best way to integrate the geophysical results with the mining method and an objective assessment of the value of the resulting mine performance benefit. Geophysical logging is already well established in many mining operations. The greatest impediments to its wider utilisation at mines are: lack of appreciation of geophysics by most mine geologists, engineers and managers; limited interpretational aids; and the necessity to re-enter completed drill holes. In this paper we endeavour to address these issues by informing mine geologists about potential applications of geophysics, by illustrating automated interpretation of geophysical logs and by highlighting the importance of emerging MWD and logging- while-drilling (LWD) technology.

Jan 1, 1997

By F. Q. Cheng

Despite the successful industrial practice to recovery KCl by flotation, the adsorption state of collectors at KCl salt surfaces is still not fully understood. In this paper, the captive bubble contact angle measurements at KCl and NaCl crystal surfaces in their saturated solutions are reported. The influence of different collectors and their concentration are considered. The results show that both cationic and anionic collectors produce a hydrophobic state at the structure breaking KCl salt sur-face, with finite contact angle values of between 30o and 40o. In contrast, the contact angle at the structure making NaCl salt surface is zero at all collector concentrations, suggesting that no collec-tor adsorption occurs, a supposition that is supported by results from molecular dynamics simulation (MDS). Further, it appears that the presence of surface defects such as edges and corners promote the adsorption of collectors at the KCl surface, and that the flotation is achieved by bubble attachment at the edges/corners of KCl particles with the formation of aeroflocs.

Jan 1, 2014

By Regina Rocha, Miguel Humpire

One of the challenges within unitary mining operations is blasting, which has a significant downstream impact on the following processes, which is why mining companies ensure the results of the blasting process through joint work with explosives specialists’ companies.

Feb 6, 2023

By Sami Makni, Ahmed Bouajila

"To remain competitive in an open market, mining companies are more and more requested to optimise their complex and highly multivariate processes. The increasing amount of process data, brought about by intensive use of instrumentation and the progress in computer data acquisition, enhances the need for more and more powerful and robust tools for the analysis and modelling of the process data. Now, with the emergence of multivariate data analysis (MDA) techniques, on-line clustering of mineral process behaviour is possible and could help in the extraction of valuable process operation indicators. MDA can be used in different mineral processes such as flotation, grinding, smelting etc. In this paper, the focus will be on grinding process as it is the one of the most costly node in the mineral processing scheme (i.e. power consuming) and it is a highly multivariable process. Particularly for primary grinding mills (SAG/AG), more instrumentation outputs and more powerful and significant process indicators are needed for efficient control and optimisation.MDA is a novel approach suitable for understanding mineral process behaviour compared to the traditionally approaches based on empirical and phenomenological modelling. Multivariate techniques can be used for several purposes. In this paper, the following objectives will be addressed:operation diagnosis: Shift differentiation and operation test differentiation can be showed by using MDA tools such as principle component analysis and factorial discriminant analysis.operation performance monitoring: operation regimes can be evaluated by clustering based on an economic criterion performance such as costs, tonnage, product quality, profit, etcIdentification of operation behaviour (monitoring) and selection of drift correction trajectories (control):MDA can be used to identify periods of unusual or abnormal process behaviour and to diagnose, if it is possible, causes for such behavior."

Jan 1, 2003

By L. A. Mekler

The recirculating furnace is primarily a heating apparatus of the convection type in which the heat-absorbing surfaces are heated by a mixture of fresh products of combustion and a portion of the combustion gases that have already given off a part of their heat in their previous passage over the heat-absorbing surfaces. In its basic conception, the recirculating furnace can be considered as a closed thermal system in which the heat-absorbing surfaces are constantly swept by a fixed quantity of products of combustion at a given initial temperature with the gases being constantly returned to the furnace and reheated before they again enter the heating zone. Gases equal in amount to those produced by the fuel burned to reheat the circulating gases are constantly ejected from the system to the stack. The recirculating furnace is the most suitable apparatus for heating by convection where low furnace temperatures must be maintained and where only a small portion of the available heat is taken out of the gases, particularly where the maximum allowable furnace temperature is low and where the final temperature of the gases is only a few hundred degrees below their initial temperature. In such cases, recirculation not only provides a method of reducing the rather high combustion temperatures of the fuel when burned without a large amount of excess air, but, by returning to the furnace the heat content of the gases at their final temperature, recovers a large portion of heat that otherwise would have been lost through the stack. The convection-type oil still is particularly suitable for the application of flue-gas recirculation. In an oil still, the heating of the oil is accomplished by applying to the tube surfaces a given quantity of heat of a certain predetermined quality, usually with the initial temperature of the gases not over 1500" F. as measured by thermocouples placed above the tube bank. To obtain the full benefit of the heating surface of the coil, the final temperature of the gases, after passing over the coil, is kept 200" to 300" higher than the temperature of the incoming oil. This final temperature varies from 500" F. for a topping still with only a slight or no

Jan 1, 1928

By V. A. Chanturiya, T. N. Matveeva, N. K. Gromova, T. A. Ivanova

"The research is aimed at solving the problem of increasing the extraction of gold from refractory ores, which are the main source of growth in gold production in the next decades. The purpose of the research is the development and scientific substantiation of the reagent modes for flotation extracting of gold from refractory ores using eco-friendly low-cost herbal modifiers (HM), providing increase in gold recovery and quality of gold concentrates. In the course of research laboratory techniques for the preparation of experimental samples of HM were developed, which included the sequence of operations of grinding Heraclium leaves and stems grinding, 2-stages extraction at a temperature of 50-60 °C, short-term ultrasonic treatment, filtration and subsequent unification of extracts. According to the developed method, the experimental samples of HM and conducted research were tested to analyze their sorption and flotation activity related to the extraction of gold from refractory gold ores.New data on adsorption and flotation properties of Heraclium stems and leaves extracts (HSE) in selective flotation of Au-sulfide minerals were obtained using UV-spectroscopy, scanning electronic and laser microscopy and atomic force microscopy. The dimensions and shapes of adsorbed hydrophilic films of herbal reagents were identified and mechanism of formation of stable insoluble compounds on the surface of minerals in flotation was explained.Research flotation tests carried out on samples of refractory gold ore of one of Russia deposits showed the possibility of effective use of herbal modifiers to improve qualitative and quantitative indicators of enrichment compared with the standard reagent regime. New reagent modes, using herbal modifiers in an amount of 5 to 10 ml of the extract (300 - 600 g / t, respectively) improves the quality of the concentrate: gold content attains 14.7 g / t, 1.34 times higher than in the baseline experiment and provides a gain of 3.13% extraction.The developed reagent regime with herbal modifiers is the author's original design, patented (patent of the Russian Federation) and have no analogues in the world of mineral processing. (Application number 2015116125 from 04.28.2015, ""The method of flotation separation of sulfide minerals using herbal modifier"", Russia). Actual application of new plant extracts as modifiers in flotation of sulfide minerals is the possibility of replacing of highly toxic chemical compounds by environmentally safe substances of plant origin. Implementation of the developed methods of extracting gold from refractory minerals with herbal modifiers will help to improve gold recovery at 3-5% and the quality concentrate of not less than 1.2 times, leading to higher productivity and a reduction of the negative man-made effects on the environment ."

Jan 1, 2016

By Rodrigo Serna-Guerrero, Ted Nuorivaara

"As the demand of raw materials increases in a global scale due to demographic and economical changes, it is necessary to find technological solutions that improve current production processes in an efficient and sustainable manner. The main objective of this preliminary study is to evaluate the properties of foam produced with a cellulose-based molecule as an alterative to commercial frothing agents in flotation operations. There are two potential advantages identified with the use of cellulose-based additives for the proposed application: i) these chemicals can be produced from sustainable sources (i.e., non-edible crops), and ii) cellulose can be functionalized with chemical groups, in order to rationally modify its behaviour. In previous studies dealing with foam stabilization, it has been proposed that some functionalized cellulose species present a self-assembly mechanism at gas-liquid interfaces. Unlike typical surfactant-based frothers, cellulose molecules form networks around the bubbles that act as protective layers to the mechanical stress and to the occurrence of ionic species. This work studied the properties of foams produced in the presence of a partially hydroxylated cellulose molecule (i.e., hydroxypropyl methyl cellulose; HPMC) under various concentrations in a laboratory-scale column. A comparison with a commercial surfactant frother (i.e., Nasfroth 240) is presented, and a rationalization of the behaviour of HPMC in terms of foam properties (i.e., surface tension, bubble size, foam depth) is proposed. INTRODUCTIONThe search for green alternatives to chemicals produced from non-renewable sources has become a topic of major relevance in industry (Choi et al., 2015). As a chemical consuming industry, the mining sector faces now the challenge of adopting new processing technologies and strategies in order to achieve the future demands of sustainability. Evidently, a move towards green chemistry can only take place by identifying substitute molecules offering potential advantages in terms of recovery and grade."

Jan 1, 2016

By E. L. Affleck, W. G. Stevenson

In both Canada and the United States, a company making a public offering of securities must comply with regulations which have been passed by Federal, State and/or Provincial Legislatures. These regulations usually require the distribution of an acceptable prospectus which provides essential background information about the issuer, the project and the share offering. when the public offering has been accepted, the unlisted company may then seek a listing of its shares for trading on a Stock Exchange. Once listed, the company will be subject to rules of the Stock Exchange. This paper will deal with the specific information required for inclusion into a prospectus being submitted for a resource company and particularly those parts of concern to mining engineers and geologists.

Jan 1, 1985

By Paul Wellman

A computer program is presented that may be used to calculate the bare equipment cost of the major processing units for any hot potassium carbonate gas purification system. The program is designed such that, with only minor modifications, it could be used with a variety of computer systems.

Jan 1, 1968

By Peter Joralemon

I want to limit my remarks to epigenetic ore deposits, but do not necessarily subscribe to the classic theories of hydrothermal ore deposition. I will consider an epigenetic deposit as a primary deposit in which the economic minerals have been introduced subsequent to the formation of the enclosing rock, regardless of the source. Past ore discoveries have been made to a great extent by prospecting techniques that have remained relatively constant over the last many decades. In many cases the discoveries have been enlarged or enhanced with the use of technical tools such as geophysics, but theoretical geology, which should serve as a foundation for exploration, has shown little progress of practical importance since the turn of the century.

Jan 1, 1967

By R. Snoby

Since its introduction in 2002, the modern air jig has processed a wide array of coals throughout the world. This paper explores the reasons and justifications for the installations and provides case history performance data. Specifically highlighted are air jig plants processing metallurgical coal in Colombia, bituminous coal in the United States and India and lignite in the United States and Spain. Each installation has unique reasons to justify an air jig facility. It is important to note that not all of the justifications were based on the ?most cost effective yield?, normally a mantra for coal preparation plant designers and owners. Dry jigging of coal has long been a proven technique for upgrading coal, the modern air jig, with its improved efficiency and operating systems simply extended the range of applications. In some cases, it even allows market quality coal to be produced when no other option is possible.

Jan 1, 2009

By E. O. Strahl

In the search for economic mineral deposits, the need for efficient mineral or chemical assays is of prime importance. Costly analytical methods and long delays in obtaining assay results severely limit the effectiveness of an exploration program. The assay problem becomes acute once a potential ore body is located and large numbers of samples are generated in close interval drilling programs. In order to avoid the delays and high costs of extensive assays, the exploration geologist or mining engineer is likely to be required to curtail his drilling program, composite samples, or restrict the required analyses to a limited number of critical elements. As a result, the definition of the potential ore body may be less than needed for final economic evaluation. The assay requirements for bauxite exploration usually involve a considerable number of total elemental and empirical analysis. Since the Bayer process for extracting alumina from bauxite involves the selective dissolution and reaction of specific minerals from the bauxite, a direct chemical analysis for elemental composition yields only a portion of the data required to effectively describe the potential economic value of ore body or deposit. To fully characterize the economic value of a bauxite requires digestion, mud separation and mud settling tests under conditions approximating a commercial Bayer plant. A close approximation of the process behavior of a bauxite also can be calculated from a combination of the chemical and mineralogical analyses. By determining the elemental chemistry, mineralogy, and Bayer plant processing characteristics of a few samples of a given bauxite, correlations can be derived that permit defining a bauxite in terms of a given set of process conditions.

Jan 1, 1977

By Y Zhang, X Yi, J Deng, J Zhao, J Song

To obtain the combustion process of a coal fire, a high-temperature programmed system is used to simulate the spontaneous combustion process of fresh and weathered coals. Both fresh coal and weathered coals from Liulingou, Inner Mongolia, China, were used to examine the gas releases from constant temperature to 650°C. Moreover, gas release rate was used to calculate the characteristic temperatures. The results showed the coal samples lasted to oxidise under high temperatures, and released plenty of heat to assist self-heating. The humic acid contained inside the weathered coal went through thermal decomposition as temperature rising and generated gases. This resulted in increasing concentrations of CO, CO2, CH4, C2H4, and C2H6. Changes of CH4, C2H4, and C2H6 gases were also similar. For weathered coal, concentrations of three gases were kept in balance under low temperatures, increased rapidly with the temperature rising. After the ignition temperature, the concentration of hydrocarbon was reduced. In addition, particle size affected coal spontaneous combustion. Coal samples with less than 0.9 mm in size produced much more CO than others. This study has examined coal spontaneous combustion caused by coal weathering during mining and its impacts on self-heating and pyrolysis in the process.CITATION:Deng, J, Song, J, Zhao, J, Zhang, Y, Yi, X and Zhang, Y, 2017. Gaseous products of weathered coal during the process of spontaneous combustion, in Proceedings Australian Mine Vent Conference 2017, pp 79–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017