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Based on experimental and computer simulation results from our group, we report a systematic, atomic level analysis of carbon dissolution from carbonaceous materials in molten iron. Experimental results on graphite/Fe-C-S system were obtained using carbon dissolution studies, XRD and FESEM investigations and were supplemented with Monte Carlo simulations. Three basic mechanisms, namely carbon atom dissociation rate, interfacial phenomena and mass transfer in the melt were found to be responsible for the overall dissolution process. While mass transfer in the melt is governed by the concentration gradients, melt composition and temperature; impurities present in ash play a significant role in the interfacial phenomena. For less ordered forms of carbonaceous materials, carbon atom dissociation rate depends strongly on the degree of long-range order and is an important rate controlling mechanism in the overall dissolution process. A systematic comparison of dissolution rates for a variety of coal-chars, natural and synthetic graphites has been carried out in an attempt to identify rate-controlling mechanisms. The structure of the carbonaceous material appears to be an important underlying factor in the carbon dissolution process.

Jan 1, 2003

By Lihong Zhou, DAVOOD BAHRAMI

A reliable and stable ventilation system is essential to the safe operation of underground mines. The stability of a mine ventilation system becomes extremely critical when responding to a fire incident, as an unstable ventilation system will pose a risk of airflow reversal. The reversed airflow could bring fire contaminants, such as toxic gases and smoke, unexpectedly to working areas. In the past few years, there has been a growing interest in the study of ventilation network stability using the concept of resistance sensitivity, which is described as an indicator of how the airflow in an airway is reacting to a resistance change of other airways. Several methods of calculating the resistance sensitivity in a mine ventilation network have been developed by researchers and scholars around the world. However, those proposed methods rely heavily on a vast number of mine ventilation simulations, which is time-consuming and computer-resource intensive, especially for a large-scale mine ventilation network. In this study, a derivative method calculating the resistance sensitivities with a single mine ventilation simulation is developed and implemented into the MFIRE mine fire simulation software. The results from the derivative method were verified against the results from a traditional method. The derivative method is proved to be reliable and accurate.

Dec 1, 2022

By R. Padilla, M. C. Ruiz, R. Villa

"Bismuth is an impurity in copper minerals where it occurs mainly as the mineral bismuthinite (Bi2S3). In smelting of copper minerals, most of the bismuth reports to the white metal, as a result, a substantial amount of bismuth accompanies the copper to the electrorefined cathodes. Thus understanding the behavior of Bi2S3 at high temperatures is crucial to eliminate bismuth before electrorefining. In this paper, some experimental data on the decomposition/volatilization of bismuthinite in nitrogen- oxygen atmospheres is discussed. The results indicated that in nitrogen atmosphere, bismuth volatilization occurs through a fast decomposition of bismuthinite to metallic bismuth and sulfur with subsequent volatilization of bismuth in the range 850-1100 °C. Similarly, in the presence of oxygen, bismuthinite decomposes to bismuth too, followed by oxidation to the non-volatile bismuth trioxide at temperatures higher than 750 °C. Both, temperature and partial pressure of oxygen affect significantly the bismuth volatilization and the oxidation rates.IntroductionCopper sulfide minerals are the major source for the production of metallic copper by pyrometallurgical processes, which are the dominant processes in the production of copper by selectively oxidizing the sulfide sulfur to SO2 and the accompanying iron in the concentrates to iron oxide, which can be conveniently removed as a stable slag.Generally, copper concentrates contain some deleterious minor elements such as arsenic, antimony, bismuth and lead, which are present as sulfides. These elements depending on their concentration may originate problems in the copper smelting processes and they can ultimately lead to a final copper product with unacceptable high levels of impurities.During the treatment of these copper concentrates by smelting, the impurities generally distribute themselves in the condensed and gas phases and they are eliminated mainly through the gas phase [1-3]. Thus, smelter off gases contains substantial amounts of volatilized impurity elements. For example, in the case of bismuth, the estimated distribution of bismuth in flash furnace smelting [2] was 15 % in the matte, 5 % in the slag and 80 % in the gas phase, and recently, for Outokumpu flash smelting Davenport [3] reported the distribution of bismuth as 30-75% in matte, 5-30% in slag and 15 -65 % in the off gas."

Jan 1, 2011

By E. Govender-Opitz, L. Lelia

The South African mining industry plays a significant role in the economy of the country. Nonetheless, the negative impacts on the environment continue to prevail. In regions where mining exists in proximity to communities, mining activities have led to the disruption of modality. Rural communities are mostly affected as they depend on land use for agriculture to sustain their livelihoods. The conversion of land for mining activities often leaves the communities vulnerable when mines close because of the limited life span of mines. An ongoing discourse focuses on how the mining industry can contribute to sustainable development of the communities in which they operate. Post-mining transformation offers an approach for the mining companies to contribute to sustainable livelihoods post-mine closure by strengthening rural-urban linkages, which ensures inclusive development of both rural and urban areas. The paper employs a case study approach to Richards Bay Minerals and the adjacent rural communities of Sokhulu and Mbonambi. It sets out to understand the post-mining transformation employed by RBM and explore the rural-urban linkages that manifest as a result. Findings show that sand dune rehabilitation employed by RBM is successful in restoring soil fertility and establishing the natural ecosystem. The casuarina planted to rehabilitate the dunes is used to spur an alternative charcoal industry post-closure. The main rural-urban linkages that manifest are flows of people due to job opportunities and flows of goods from the sale of charcoal produced. However, there is a lack of communication and lack of authority to ensure responsible management of the casuarina plantation and equitable sharing of benefits. The paper recommends that other post-mining transformation strategies such as eco-tourism should be explored and that the government, at both national and local level, the community and the mine should be involved to ensure overall success and sustainability of the strategy. Keywords Post-mining transformation, rural-urban linkages, alternative land use

Jan 1, 2020

By V. E. Edlund

As part of its efforts to devise new and improved methods for recovering lithium from unconventional resources , the Bureau of Mines investigated a lime -gypsum- roast , water- leach technique for processing lithiumenriched ( 0.01-0.68 pct Li ) clays . This report presents the results of a study of the technical feasibility of extracting lithium from raw material representative of clay beds associated with the McDermitt Caldera complex in Nevada and Oregon . prepared from water used Pellets suitable for bench-scale roasting studies were mixtures of minus 200 -mesh clay , limestone , and gypsum , with as the pelletizing agent . Roasting pelletized charges at 900 ° to 1,000° C temperatures for 1- to 4-h periods produced calcines that leached readily , yielding water - soluble lithium sulfate ( Li₂SO4 ) . A 5-3-3 ( weight ratio ) mix of clay , limestone , and gypsum produced calcines with the best leaching characteristics . More than 91 pct of the contained lithium was extracted from pelletized mix batches roasted in covered refractory boats . Lithium recovery decreased to about 87 pct when the mix was roasted under dynamic conditions in a gas - fired rotary furnace . A reaction mechanism was postulated which indicated that dilution and loss of SO2 and oxygen in the combustion exhaust adversely affected the leachability of the dynamically roasted calcine .

Jan 1, 1983

By Wang Xuewen, Bao Qingbao, Xie Jiacheng, Yan Zewen

This study puts forward a virtual memory cutting method based on the prediction of AFC shape. The integrated key technologies include the generation of virtual teaching cutting curve, the height adjustment strategy of front and rear drum, cutting height adjustment strategy, the reciprocating cycle of cutting technology and so on. Through the two algorithms, SVM and ELM, the form of the next working cycle can be obtained by rolling prediction using the form information of AFC in the first several circulations. Based on the obtained dynamic fluctuation of the form in the vertical and horizontal working faces, the position and cutting information of the shearer during its operation can be controlled and predicted in advance, the memory cutting template can be adjusted and modified in time. Employing this method, the more stable, accurate and timely memory cutting of the shearer under the uneven coal seam could be realized.

Aug 16, 2021

By C. J. Pritchard

As productivity improvements reduced the number of continuous miner sections from seven to three while maintaining full productive capacity, a decision was made to test an advancing tailgate ventilation system on the shortwall mining section. Having the shortwall mine its own return air system has freed the third mining section for more productive, less costly mining. The advancing tailgate has provided effective ventilation across the face and gob with acceptable pressure losses. The tailgate development continuous miner section has been since transformed from a low productivity part-time function to a high productivity development/retreat panel and is available for long term mine development duties also.

Jan 1, 1989

By C. E. Tsoutrelis

A new method for determining rock drillability in diamond drilling is discussed; the method takes into consideration both penetration rate and bit wear. The method is based on drilling a rock specimen under controlled laboratory conditions using a model bit. The technique used for determining the experimental variables is extremely simple, quick, and reliable. Drillability is then determined by the mathematics of drilling. In considering the different factors that affect diamond drilling performance, the nature of the rock to be drilled is of outmost importance since it affects significantly the drilling costs and such other variables as bit type and design, drilling thrust, and bit rotary speed. Many attempts have been made to study this effect by correlating actual drilling performances either to certain physical properties of the rock being drilled1-? or to test drilling data obtained under laboratory conditions.7-13 These attempts were aimed at providing a reliable method of predicting by simple means the expected rock behavior in actual drilling, thus giving the engineer a tool to use in estimating drilling performances and costs in different types of rock. The purpose of this paper is to describe such a method by which rock drillability (a term used in the technical literature to describe rock behavior in drilling) could be determined in diamond drilling. It is believed that the proposed simple and reliable method will cover the need of the mining industry for a workable method of measuring the drillability of rocks. It should be emphasized, however, that since drill-ability depends on the physical properties of rock and each drilling process (diamond, percussive, rotary) is affected by different or partly different rock properties,14-l6 the proposed method of determining rock drillability cannot be extended to the other drilling processes. The results presented in this paper form part of an extensive three-year research program carried out by the author in the laboratories of the Greek Institute of Geology and Subsurface Research. During this period the effects of the physical properties of rocks and of such operational variables as drilling thrust and bit rotary speed in diamond drilling were investigated in detail. DRILLABILITY CONCEPT The literature is not devoid of drillability studies. While there are a number of investigators1,3,5-7,9-0,12-13,17 who have attempted to establish by direct methods (i.e., drilling tests under laboratory conditions) or indirect (i.e., through a physical property of rock) an index from which the drilling performance in a given rock may be estimated, very few6-7,9,12, of the proposed methods seem to be of much practical value to the diamond drilling engineer and none to date has been universally accepted. Commenting on the proposed methods for assessing rock drillability, Fish14 remarks that "for a measure of drillability to be accepted it is essential that penetration rate at a given thrust and bit life are elucidated as otherwise the method is of little value." This statement should be examined in more detail by making use of the penetration rate-drilling time diagram obtained in drilling a rock under constant operational conditions. Furthermore, the merits of using this diagram to describe rock drillability will be pointed out. At the same time reference will be made to this diagram when discussing some previously proposed methods. Fig. 1 illustrates such a diagram for three rocks,A, B, and C, which have been diamond drilled under identical conditions. It is assumed here that rocks A and B have the same initial penetration rate, i.e., VOA = Vog, but since rock B is more abrasive than A, rapid bit wear occurs and as a result the fall of its penetration rate with respect to time is more vigorous than in rock A. This is shown graphically by a steeper V = f(t) (0 curve in this rock than in rock A. Rock C has a lower initial penetration rate, due to higher strength properties16 but since it is not very abrasive, only a slight fall of its penetration rate occurs during drilling (in this category are some limestone and marbles with compressive strength above 1000 kg per sq cm). It follows from the foregoing considerations that the characteristic for each rock curve (I) is a function of (i), the penetration rate of the rock Vo recorded at the instant of commencing drilling, which determines the starting point of the curve (1) on the y-axis and (ii), the abrasive rock properties which determine the rate of fall of Vo with respect to time. Thus, curve (I) provides an actual picture of the rock behavior in drilling for given operational conditions, and it can be used with complete satisfaction to assess rock drillability. It can be seen clearly from Fig. I that proposed methods for assessing rock drillability by measuring the

Jan 1, 1970

By S. A., Taylor

IT is very difficult to arrive at exact figures for the cost of maintaining excess capacity of coal mines, but we can approximate the various items. To do this, I will take the Pittsburgh district of Pennsylvania and the other districts can be compared to this one. I believe we can take the depreciation item of plant ac- count as a whole and discount it over a period of 20 years; while this is high for some items it is low for others and I believe it is not far from a safe basis. This equals 5 per cent per year, and this depreciation will take place about as rapidly when not in use as when in operation. A fair value in the Pittsburgh district to- day for plant and houses is close to $4 per ton per annum. At 5 per cent this will equal 20 cents per ton per year. The item of keeping the mine in condition, free from water, etc., will be close to an average of 2y2 cents per ton per annum.

Jan 1, 1928

By John A. Herbst, Ming Song, Xiangjun Qiu

It has been known for sometime that as wear occurs in tumbling mills there is an associated change in mill throughput. These changes have traditionally been simplistically, attributed to “mill volume effects”. New high fidelity simulation tools (involving DEM, CFD and Breakage models) are now giving new “microscale” insights into the complex interactions that occur between evolving lifter/liner profiles and breakage. The study described here shows that these new tools can allow the design of wear part profiles which will maximize mill productivity over the entire life of a liner/lifter system.

Jan 1, 2003

By R. E. Snow

The analysis of ground water inflow and discharge from underground mines has received increased attention in recent years due to environmental issues which must be addressed under current state regulations for coal mining and processing operations. In particular, coal operators must assess the probable hydrologic consequences associated with mining activities, and must plan for mine water handling during operation and following completion of mining. The prediction of ground water inflow rates with future mine development allows preparation for potential operational problem and identification of inflow reduction methods. Similarly, evaluation of mine discharge rates is necessary to address potential long-term acid mine drainage (AND) concerns. As part of mine discharge analyses, methods. to control seepage and AMD can be considered. The objective of this paper is to discuss the practical applications of mine inflow and discharge analysis, describe the typical flow components, outline the procedures necessary to perform the analysis, and illustrate the modeling procedures and potential results of mine inflow and discharge predictions.

Jan 1, 1990

By L. H. Munson, D. E. Hadlock, L. F. Munson, R. L. Gilchrist, P. D. Robinson

All uranium mills are required to perform sampling and analysis for radioactive particulates in their gaseous effluent streams and in the environment. Pacific Northwest Laboratory was requested by the U.S. Nuclear Regulatory Commission (NRC) to provide technical assistance to them for their Uranium Mill Health Physics Appraisal Program. In conducting appraisals, air sampling methods used at NRC-licensed mills were reviewed and several deficiencies noted. This paper includes only environmental and effluent particulate sampling although much of the information is applicable to both in-plant and environmental samples. First, the components of a proper sampling program are discussed: program objectives, program design, sampler design, analyses, quality assurance, and data handling. Then the specific deficiencies, or the "pitfalls" from the first 8 mill appraisals are discussed. The first consideration in establishing an air sampling program is defining the objectives of the program. What is air sampling suppose to accomplish? Many of the deficiencies we have observed have resulted because the desired objectives were not clearly established in the minds of the radiation safety staff. PROGRAM OBJECTIVES An environmental air sampling program ought to fulfill the following seven objectives. The first is to: 1) [demonstrate regulatory compliance]. Although a goal of most programs, regulatory compliance, is not well understood. One has not only to comply with the conditions of the source materials licensee, but one must also demonstrate compliance with 10CFR20 and 40CFR190. For example, 10CFR20.106 states: "A licensee shall not possess, use, or transfer licensed material so as to release to an unrestricted area radioactive material in concentrations which exceed the limits specified in Appendix B, Table II of this part .... For purposes of this section, concentrations may be averaged over a period not greater than one year." Even if a mill's license does not require sampling at the site boundary of maximum concentration, a sample may be necessary to demonstrate compliance with 10CFR20. Most mill personnel are painfully familiar with 40CFRl90.10, which states: "Operations.... shall be conducted in such a manner as to provide reasonable assurance that: (a) The annual dose equivalent does not exceed 25 millirems to the whole body.... of any member of the public as the result of exposures to planned discharges of radioactive materials, radon and its daughters excepted... from uranium fuel cycle operations..." This means a licensee's sampling program must give "reasonable assurance" that the member of the general public receiving in the most exposure gets no more than 25 millirems per year. The sampling program necessary to provide that assurance may or may not be a license requirement. However, merely meeting the license requirements and the explicit regulatory requirements does not necessariarly ensure an adequate effluent and environmental air sampling program. The second objective of the environmental air sampling program, is to 2) [identify the source(s) of contaminants]. This will include not only the routine program, but special sampling for verification of sources and nonsources. Only after sampling can a mill operator be assured that roof vents, laboratory hoods, and other localized ventilation systems are not making a significant contribution to environmental releases. An environmental sampling program should also allow the mill operator to fulfill the third objective, to 3) [estimate exposures]. Even before 40CFR190, a sampling program should have provided the mill operator with the information necessary to determine the dose to the "fence post" person, or at least to determine if doses were well below the 10CFR20 limits previously allowed. The program should 4) [detect and measure unplanned releases]. If there is a fire, a scrubber failure, or if a drum of yellowcake breaks open, measured releases will almost always be lower than conservative estimates. Whether or not a system to provide sampling during accidents is needed is almost always a cost-benefit decision. In general, uranium operations do not sample just in case an accident may occur. Yet they may decide on continuous air sampling in lieu of intermittant sampling partially because of the potential for accidents. Another objective of air sampling is 5) [to provide information on the effectiveness of control systems]. This is always a concern with new or modified equipment and may dictate sampling frequency in other situations as well. For instance, if a small leak in a bag filter cannot be detected by other means, then more frequent stack sampling may be indicated. A routine effluent and environmental monitoring program should also fulfill the sixth objective,

Jan 1, 1981

"Injection technology has been an important subject from the early days of ladle metallurgy until the present. During the last decade, there have not been many publications in the area of injection technology. It is the author's opinion that with the challenge to find new solutions especially to environmental and energy related problems as well as better understanding of phenomenas from computer modelling, a new era of inventive injection technology developments is at hand. This is illustrated in the article with examples from six different areas where MEFOS is or have recently carried out R&D work related to issues from the injection technology field. IntroductionThe boom in injection technologies came with the introduction of ladle metallurgy treatment during the '70s and '80s. Since then, the theories and principles have been thoroughly laid down by a number of scientists and also published at several early SCANINJECT conferences.Not many new technologies/applications have been presented during the last ten years. This might lead one to believe that everything is known and done. Those, like MEFOS, who are challenged to find technological solutions to a number of environmental problems and energy saving issues in the pyrometallurgical field are, however, continuously faced with the task of developing new injection technologies.Especially, the call for sustainable technologies to solve environmental problems is a challenge for metallurgists all over the world and it will surely induce a revival of injection technologies. So, in order to encourage all injection experts, let us share some new experiences and let us encourage each other's creativity to solve some of the demands of the future society.The following show some examples of technologies under development, or recently tested."

Jan 1, 1996

By S Hapugoda, J R. Manuel, M J. Peterson, A Poliakov, E Donskoi

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Aug 12, 2013

By L Dyer, A Keith, G D. Corder

As mining activity moves to remote and less developed locations globally, a holistic approach to mine development is fundamental for achieving a balance between strong financial returns and corporate social responsibility and transparency. Key inter-related fundamentals such as social licence to operate, life-of-mine operational planning, minimising environmental impacts and, most importantly, attractive investment returns for the mining company all contribute to the viability of any new mining project.However, the typical practice in the mining industry is often to treat environmental and social/community aspects as separate compliance issues that are dealt with at minimum cost and disruption to the project and resulting operation. This often results in less than optimum environmental and social outcomes, and presents considerable liabilities at the time of closure when rehabilitation programs continue to require funding when all revenue has ceased.The five capitals model seeks to identify each of the key contributors to sustainable development as financial, manufactured/physical, social, human and natural to formulate a type of triple bottom line approach balancing these often competing project factors. The SUSOP® sustainability risks and opportunities framework, developed by the mining industry, bases its approach on the five capitals model and proposes an approach that breaks down enterprise silos to identify innovative solutions for life-of-mine sustainability. This framework has been developed with the nature of mining projects in mind in order to produce approaches and outcomes relevant throughout the life cycle from the planning phases, through project design and construction into operation and closure.This paper argues the need for a more holistic approach to the development and operation of mining projects, and presents case studies where a holistic approach has been applied, in whole or part, and discusses the lessons learned from these case studies.CITATION:Corder, G D, Keith, A and Dyer, L, 2014. A capitals based approach – leading innovation in planning for life-of-mine sustainability, in Proceedings Life-of-Mine 2014, pp 499–512 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Jan J. Cilliers, Nicolas Barbian, Esther Ventura-Medina

"Mineral froth flotation is one of the most widely used processes to separate particles of valuable mineral from its associated gangue. It involves the selective separation of the hydrophobic particles from the slurry into the froth. The hydrophobic particles attach to the air bubbles and rise up to the froth phase on top of the slurry. The valuable mineral is collected when the froth overflows the cell wall. The separation performance of the process can be linked to the amount of solids and valuable material loaded on the bubble shells. In addition, it is well known that in most mineral systems, the presence of solids can enhance the stability of the froths. How the solids get to be distributed and what proportion is actually attached and stabilising the bubbles is not well known.This study aims to establish the relationship between operational variables, solids loading on bubbles and flotation performance. For this purpose, a series of industrial experiments to sample the solids in the bubble films under different operational conditions were carried out in two copper concentrators under steady state conditions. Samples of the lamellae were taken by touching the top surface of the bubbles with a glass slide. The amount of solids and liquid per unit area in the bubble lamellae can subsequently be estimated gravimetrically and by image analysis. The grade of the attached particles was also measured by adequate sampling. This gives an indication of the maximum grade that could be achieved from the process under the operating conditions."

Jan 1, 2003

By L. E. Schultze

The Bureau of Mines operated a mineral recovery unit to recover metal values from post-flash geothermal brines from the Salton Sea known geothermal resource area as part of its research into the use of plentiful resources. The brine was available for metals recovery after its heat content had been used to generate electricity. The brine source was treated with lime to precipitate the contained iron, manganese, lead, and zinc before injection of the heat-depleted brine into the underground reservoir. Data are presented on the effects of process variables, such as rate and method of lime addition and air oxidation versus air exclusion. Variations in precipitation of metal values, composition of precipitates, effectiveness of slurry thickeners, and methods of treating the precipitates to recover metal values are discussed.

Jan 1, 1982

By Alessandro Blasi, Massimo Morgana, Corradino Sposato, Pietro Garzone, Giuseppe Devincenzis

The rare earth elements are essential for a diverse and expanding array of high-technology applications, which constitute an important part of the industrial economy of the 21st century. As a matter of fact, rare earth has been listed in the category of strategic elements in many countries becoming a core business for international research. Experimental tests have been carried out on a bench scale battery of mixer settler composed of 24 stages, each one with a volume of 150 ml. These trials have been performed at room temperature checked by a micro-climatic control system. The battery was setted in two sections: extraction and scrubbing section. Rare earths concentrations were obtained by ICP-OES analysis made on aqueous phase and on the stripped from organic phase. We obtained a complete separation of light rare earth (La, Ce, Pr, Nd) in two sub-groups: La/Ce and Pr/Nd.

Jan 1, 2014

By G Anders

Underground tests of slusher cables at first might seem to be quite simple and inexpensive. They do, however, take a long time and give results that may be ambiguous and unreliable. Also, because underground test conditions are not exactly duplicable, tests carried out at different times or in different mines could not be compared. An attempt was made to develop a laboratory test method that would provide for all factors affecting slusher cable performance underground in such a way as to make it possible to achieve comparable results from different series of tests by exactly duplicating test conditions. Such a method should also make it possible to vary individual factors systematically in order to give a proper assessment of the effect of changing conditions on cable performance. A set of tests, comparing the same two types of cable both underground and in the laboratory, is described. AN assignment at the Algom Nordic mine called for the comparison of two types of %-in. slusher

Jan 1, 1964

By Partridge AC

The measurement of particle size is very important in many industries. Comments in this paper refer principally to the Mineral Industry and in particular to Coal Mining and Coal Preparation. The objective is to indicate the importance of particle size in process design and process assessment and to describe techniques for particle size measurement and the presentation of results.

Jan 1, 1984