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By Marcus Neves, Eventomar Junior, Adilson Castro, Leandro Silveira, Sérgio Augusto

The collapse of the Vale S.A. mining tailings dam in 2019, a tragic event that shook Brazil and the world, had consequences that transcended the immediate pain and devastation. Among them, the suspension of rock blasting activities in several mines in the Quadrilátero Ferrífero region of Minas Gerais, Brazil. This measure, taken as a precaution and with the aim of ensuring the safety of nearby geotechnical structures and the population, had a significant impact on the mining production chain. To overcome these challenges and resume blasting activities in a safe and sustainable manner, the mining industry has been dedicated to developing and improving solutions. One of the promising alternatives is the signature hole technique, used in conjunction with attenuation laws. The complex geology of the Quadrilátero Ferrífero, with lenses of compact ores immersed in friable materials, the presence of discontinuity families, and the emergence of geological faults, requires detailed analyses and specific adaptations of the signature hole technique and constant monitoring of the vibrations to calibrate the attenuation laws to ensure compliance with permissible limits and safety of the operations. To demonstrate the methodology, a case study in Abóboras Mine was described. Additionally, the challenge of achieving the desired level of production while controlling vibration and slope damage has driven the development of new charging and timing techniques. To address this challenge, a comprehensive approach was undertaken. A substantial database containing more than 4,000 registers of blasting-induced vibration events from 520 blasts was meticulously compiled from 2020 to 2023, 6 different attenuation laws were established and continuously calibrated with 99.3% of compliance regarding permissible limits of vibrations. The successful implementation of these actions allowed for the resumption of blasting, increasing production from 10 million metric tons to 43 million metric tons per year assuring sustainable operation.

Jan 21, 2025

By Mitsutaka Hino

The contents of gangue minerals, such as A1203, P205, crystalline water and so forth in the iron ore imported to Japan tend to increase year by year, Though the increments of such gangue contents are approximately 0.1-0.2 mass%, some problems for the blast furnace operation in ironmaking process have already been reported, In order to clarify the mechanism of harmful effect caused by the small increment of gangue minerals, mainly A1203, on the blast furnace operation, the dripping behavior of FetO-CaO-SiO2-AI2O3-MgO slag from the iron funnel, which simulated the micro-porosity in sinter ore, has been observed with the wide range of basicity, Al2O3, FetO and Mgo contents. The effect of MgO on the dripping behavior of slag has been summarized in this paper, It was found that the addition of 2mass% MgO resulted in large increase of hold-up on the most of the conditions. When FetO content was less than 20mass% and the basicity was lower than 0.8, MgO lowered the hold-up even if the slag contained 10mass% Al2O3. Every slag hold-up showed the minimum at the basicity of less than unity on the conditions of constant FetO and A1203 contents. This trend became remarkable when the slag contained 2 mass% MgO.

Jan 1, 2003

By A. K. Bhattacharyya

The excessive displacement of the seam floor in headings (i.e. roadways) called 'floor-heave' is often experienced in the underground mines of the Southern Coalfield of New South Wales. Apart from interfering with the mining operations, the phenomenon could be detrimental to the stability of the pillars left for support leading to an unpredictable increase in the subsidence of the overlying strata. The latter could pose a serious problem, particularly in the design of partial extraction layouts of mining for areas where subsidence is to be controlled. The susceptibility of the floor of different rock materials and thicknesses in a given 'panel and pillar' partial extraction geometry was examined by two-dimensional Finite Element Modelling of the displacements, stresses and failure zones around the excavations. The modelling, assuming elastic behaviour of the materials, indicated that the maximum vertical displacements of the floor increased substantially as the Young's Modulus of the material decreased to less than 7GPa and the thickness of the layer increased. The results also discount the possibility of a properly designed panel and pillar geometry in the Southern Coalfield of New South Wales being unable to adequately control surface subsidence through the pillar, or its core independently of the yielded ribs, penetrating the floor.

Jan 1, 1992

By Kotaro Ohga, Kiyoshi Higuchi, Zhang Xun Tao

In Japanese coal mines, drivage works of in-seam gate roads are mainly carried out by blasting methods. Changes of methane concentration in gate roads are recorded by centralized monitoring systems in general. To obtain useful information from the recorded data, authors analyzed changes of methane concentration for 3 hours after blastings. As a result, the changes of methane concentration with time can be divided into five distinct patterns. It is thought that appearance of the each pattern depends upon the geological conditions of the surrounding of the headings. Therefore, we attempted to confirm such observations by simulations using mathematical models.

Jan 1, 1989

By A. G. Mayton, D. H. Ambrose, C. C. Jobes, N. K. Kittusamy

In a systematic study, the National Institute for Occupational Safety and Health (NIOSH) evaluated seat designs in low- and mid-seam shuttle cars during production operations at two underground coal mines in southern West Virginia. The purpose was to support, with additional data, earlier findings that NIOSH ergonomic seat designs (featuring viscoelastic foam padding and lower-back support) may help reduce health risks to operators of coal mine shuttle cars. Eight shuttle car operators evaluated seven seat designs (one already in use in each vehicle and five NIOSH designs) relative to perceived and measured whole-body vibration (WBV) exposure (including vehicle jarring/jolting) and discomfort. Operators’ perceptions using a visual analog scale (VAS) and questionnaire ratings were compared with International Standards Organization (ISO) 2631-1:1985 fatigue-decreased proficiency (FDP) limits and measured WBV levels on low- and mid-seam shuttle cars. Objective and subjective data results indicated that NIOSH seat designs (with added adjustability, lower-back support and improved seat padding) performed better to reduce vehicle jarring/jolting levels and that shuttle car operators favored them over existing seat designs. The NIOSH low- and mid-seam shuttle car seats showed 45 to 77 percent better performance in FDP and 9 to 60 percent better performance overall in operators’ ratings. Considering the VAS results for low- and mid-seam shuttle cars under no-load conditions, operators rated the level of jarring/jolting 18 to 89 percent lower with the NIOSH seats. Reductions in measured vehicle jarring/jolting were 19 to 46 percent for the three-directional vector sum accelerations relative to the existing seats on the low- and mid-seam shuttle cars. Questionnaire responses indicated that operators for both shuttle car models rated NIOSH seat designs as more comfortable overall. Vehicle operators most frequently suggested adding armrests to improve the seats on the mid-seam shuttle car. A suggested improvement for the low-seam shuttle car was to make the seat a better fit for the operator compartment, which would enhance clearance between the operator and vehicle controls and allow for better seat adjustment and operator visibility.

Jan 1, 2009

By H. R. Deeth, C. J. Koenig

About ten years ago nepheline syenite was introduced to the ceramic industry and the material has now found application in the various branches of the industry, namely, as a vitrifying agent in white-wares and as a source of alumina and alkalies in glasses, glazes, and porcelain enamels. Spencel described the early mining and processing developments regarding this material. Since the time of his article many research papers have appeared relating to the usage of nepheline syenite but little has been published relative to subsequent mining and processing methods. A complete indexed review of the literature was issued recently by Ohio State University.2 Since "Lakefield" nepheline syenite from Blue Mountain, Ontario (Fig I); is the only commercial ceramic-grade nepheline syenite now being marketed on this continent, discussion is limited to this operation carried on by American Nepheline Limited, Lakefield, Ont., and its subsidiary in the United States, American Nepheline Cory. at Rochester, N. Y. The Deposit Blue Mountain is a long ridge rising to an elevation of about 350 ft at its highest point above the surrounding country and extending for about six miles in a northeasterly direction across Methuen township, Peterborough County. The rock of the Blue Mountain central alkaline intrusive is fine grained, light colored and of even granitic texture. The solidified mass consists predominately of the minerals albite, nepheline and microcline in order of abundance. The average mineralogical composition for the deposit obtained by a study of 112 samples taken regularly over the whole formation is as follows:3 Volumetric Mineral Per Cent Albite.................... 54 Microcline................ 20 Nepheline................ 22 Muscovite................ 2 Mafics.................... 2 (Biotite, hastingsite, magnetite) Total................... loo The mineral nepheline (or nephelite) belongs to the feldspathoid group but is lower in silica content than are the feldspars. It is a silicate of soda, potash, and alumina (NaKAl2O32SiO2). Its presence with albite (Na2oA12O3 6SiO2) and microcline (K2O A12O3 6SiO2) gives the Blue Mountain deposit an alkali content of 15 pct and an alumina content of approximately 24 pct. While this huge alkaline mass is somewhat variable mineralogically, it has a uniform chemical composition. When the iron, mostly in the form of magnetite, is removed during processing, a remarkably uniform finished product is obtained. Geological surveying has disclosed many million tons of nepheline syenite in the Blue Mountain deposit. Diamond drilling in the area where mining is now being carried out indicates a block of about one million tons.

Jan 1, 1949

By Seneviratne SP

The excessive displacement of the seam floor in headings (i.e. roadways) called 'floor-heave' is often experienced in the underground mines of the Southern Coalfield of New South Wales. Apart from interfering with the mining operations, the phenomenon could be detrimental to the stability of the pillars left for support leading to an unpredictable increase in the subsidence of the overlying strata. The latter could pose a serious problem, particularly in the design of partial extraction layouts of mining for areas where subsidence is to be controlled. The susceptibility of the floor of different rock materials and thicknesses in a given `panel and pillar' partial extraction geometry was examined by two- dimensional Finite Element Modelling of the displacements, stresses and failure zones around the excavations. The modelling, assuming elastic behaviour of the materials, indicated that the maximum vertical displacements of the floor increased substantially as the Young's Modulus of the material decreased to less than 7GPa and the thickness of the layer increased. The results also discount the possibility of a properly designed panel and pillar geometry in the Southern Coalfield of New South Wales being unable to adequately control surface subsidence through the pillar, or its core independently of the yielded ribs, penetrating the floor.

Jan 1, 1992

By J. C. M. De Souza

The Samarco pipeline, the longest in the world for iron ore slurry transportation, started operation in 1977 to transport concentrate from the Germano facilities, in the state of Minas Gerais, to the pelletizing plant, located 396 km away, in the state of Espirito Santo, on the south-east coast of Brazil. Designed for a nominal capacity of 12 million tons per year, the pipeline reached 15.5 million/year due to operational improvement and, in late 2005, it was resized to transport 16.5 million tons per year, with the installation of a booster station. In order to ensure the accurate performance of the system, a pipeline cleaning programme was carried out and, since it has been29 years from the operation start-up, precise knowledge of the pipe condition would be fundamental to guarantee the success of the project. The cleaning programme demonstrated the potential of operational gains from this initiative, and its effect on the corrosion control and future measures, which should be permanently adopted to maintain the improved capacity. The intelligent pig runs provided essential data used to establish a pipeline integrity programme that allowed Samarco to develop a pipe repair plan based on the severity and significance of the features and to implement a future pipe replacement plan.

Jan 1, 2007

By Ross W. Smith, Nikhil Trivedi

The variation of point of zero charge (PZC) of both simple and complex oxide minerals was studied as a function of aging time in water. In most cases the PZC's of the simple oxides moved toward more basic pH values with aging time. Evidence to date suggests that this phenomenon relates to dissolution of disturbed layers on the mineral's surface accompanied by later readsorption of metal hydroxy species back onto these surfaces. The readsorption takes place after the solution becomes supersaturated with respect to some crystalline phase. The variation of PZC's of complex oxides as a function of aging time in water is apparently related to several different mechanisms. In a few cases PZC shifted toward more basic values with time. This shift could be attributed to much the same mechanism as for simple oxides. In most cases, however, PZC of complex oxides shifted toward more acid values with aging time, probably because of loss to solution of soluble cations whose oxides possess basic PZC's.

Jan 1, 1975

By Ing. E. h. Martin Herrenknecht

The paper will describe a number of developments and innovations now in use in microtunnelling machines. These include the use of fuzzy logic steering systems, the proven ability to successfully undertake complex curved microtunnel drives, the ability to complete ultra long drives using microtunnelling techniques, and machines with access to the face of the machine from inside the machine. The ability to tunnel in relatively hard rock utilizing a rock head with back loaded cutters changeable from inside the microtunnel machine and the ability to utilize microtunnel machines in multi modes, such as hard rock mode, “open” mode, EPB mode, and slurry mode with the same base machine again with access to the face of the machine will be described. In addition, the latest computer technology gives the operator “full visualization” of machine functions together with the ability to data log machine operating parameters. Reference will be made to a number of projects worldwide recently completed or under way where these innovations have successfully been utilized.

Jan 1, 1999

This paper examines the new water-hydraulic (hydropowered) drill rigs that have been developed and proven in the last decade primarily in tabular, shallow-dipping, narrow-reef hard-rock South African mines. These include drill rigs for flat-end tunnel development, narrow inclined raises and winzes, large inclines and declines and longhole-based developments such as ore passes and vent raises. The hydropower technology rigs offer advantages both in safety and performance over traditional compressed-air-powered, hand-held development, and are generally more cost-effective than imported oil electro-hydraulic drill rigs. Furthermore, hydropowered rigs are inherently energy-efficient. The benefits of hydropower are discussed and a ?comprehensive development model? is presented which demonstrates that ore-bodies can be accessed in significantly shorter times. ?Localized? half level hydropower systems are introduced and a range of ancillary equipment available is listed.

Jan 1, 2012

By S. A. Ford

I would like to call the attention of our Bessemer steel manufacturers to a few facts in regard to the action of the manganese in the spiegel with the oxide of iron in the blown iron. The oxygen is united with the iron as a magnetic oxide, as Gautier asserts, and this oxide is reduced to a protoxide by one atom of the manganese uniting with one atom of the oxygen of the magnetic oxide of iron. This oxide of manganese and the protoxide of iron thus formed unite with the silica which has been formed by the oxidation of the silicon in the pig iron. Mr. Snelus and others

Jan 1, 1881

By S. P. Kinney

[The blast-furnace operator is often confronted with the problem of determining the size of the materials which are used in the furnace burden. The statement is heard that the coke is larger or smaller or that certain ore is finer than that previously used. A screen analysis of the materials used gives a measure of the different sizes of materials in an aggregate. When one is fine and the other is coarse, the difference is obvious; but when the materials are of similar sire, it is more difficult to estimate the degree of finances or coarseness. In considering raw materials it would be desirable to be able to judge the size of the radio ideal materials entering the furnace and the burden as a whole, by one representative value, such as the average size of particle. Previous work by Perrott and Kinney3 developed a method for measuring the average size of particle in a mass of finely ground materials, and an attempt will be made to apply this method to the materials included in the blast-furnace charge and to the entire burden.]

Jan 1, 1930

By S. Shapiro, G. Krauss

We will reply to Dr. Pitsch's discussion by 1) presenting in greater detail the single surface trace analysis which we performed on the reversed austenite plates in a single parent plate of martensite of known orientation, 2) relating the results of our analysis to the conclusions which Dr. Pitsch makes on the basis of our data, and 3) examining the validity of our selection of twenty-nine individual traces from the over 200 austenite plates which were observed in a surface of this single martensite plate. Fig. 7 shows a standard (001) projection of the martensite plate from which the austenite-martensite interface traces were taken. The traces are plotted on the projection as the small solid circles, and the great circles corresponding to the loci of plane normals which could contain each trace or could intersect the surface plane along the measured directions are also plotted. It can be seen that these great circles intersect at a point which corresponds to the normal of the surface plane on which the traces were observed. Also rate which occurred only at particularly low heating rates, see Figs. 1 and 3 in the paper.2 Since in this case the interpretation of Jana and Wayman is plausible and since we have no alternative to this interpretation, we would like to state only that the existence of a diffusion-controlled reversal at low temperatures seems to be not yet proved beyond any doubt. The author wishes to thank Professor G. Krauss for making available his manuscript prior to publication. It is also a pleasure to acknowledge the lively written discussions, which the author has had with Professors G. Krauss and C. M. Wayman prior to this communication. The financial support of the Deutsche For-schungsgemeinschaft for the work on which this communication is based is also gratefully acknowledged. plotted within small dotted circles which represent a i3 deg scatter in each of the twenty-four unit stereo-graphic triangles are our A and B poles7 and the pole P determined by Kessler and itsch.' The data presented in Fig. 7 permit a direct association of the measured traces and the various proposed habit plane poles for the reversed austenite plates in the martensite crystal. If the sample measurements do in fact

Jan 1, 1969

By Joan C. Biordi

[Composition profiles for atomic, radical, and stable species, as well as temperature and area expansion ratio profiles, have been determined for a nearly stoichiometric CH4-02-Ar flame and one to which 0.3 percent CF5Br inhibitor had been added. Net reaction rate profiles were calculated for all the observed species. For the normal flame, these and the mole fraction profiles gave rate coefficient information about the elementary reactions in the methane flame, for example, CH. + 0 4- H2CO 0 H, k4 = 1.05 X 1014CM3 mole-1sec-1 for 1,550§T 0,725' K; CO + OH 4 C02 + H, k6= 4.7 X 1011 for 1,350{T X1,750° K. Comparison between the inhibited and normal flame showed that A] and [CH3] were significantly reduced at the lower temperatures in the inhibited flame even though in the hot gas region the [E] [OH!, and [0] were essentially the same in both flames. The CF3Br disappears very early in the flame, relative to the fuel, and the reaction primarily responsible for its disappearance is H v CF3Br 4 HBr + CF3, where k7 is found to be 2.2 X 1014 exp(-9460/RT) for 700-1,550° K. Reaction of the inhibitor with methyl radicals provides for the relatively small amounts of CH3Br observed, but CH3 + Br2 - CHs Br + Br must also occur. The HBr formed reacts rapidly with H atoms to form H2 and Br, but the reaction is soon "balanced" in the flame as may be demonstrated by calculation of the equilibrium constant at various temperatures. The fluoro-carbon fragment produced in reaction (7) also reacts rapidly, in part with methyl radicals to give the observed elimination product CH2CF2 Later in the flame, above -1,400' K, F2CO is formed from the reaction CH2CF2 + 0 P F2CO + CH2 and k., -1.5 X 1013 at 1,600° K. The rather slow decay of carbonyl fluoride is attributed to reaction with H atoms according to the sequence F2CO I H - HF + FCO and FCO + H HF + CO.]

Jan 1, 1975

By Alfredo Valencia-Toledo

This study delves into the satisfaction levels of indigenous communities in Apurimac-Cusco, Peru, concerning mining activities in their region. Our primary objective is to elucidate the interrelationships among observable variables, which are conceived as linear combinations of multiple factors. Employing the statistical methodology of exploratory factor analysis, we aim to pinpoint the pivotal factors influencing the progress of mining activities in Apurimac-Cusco. Through our analysis, we have identified eight key factors that exert a significant impact on mining’s sustainable development in the area. These factors encompass diverse facets, ranging from the support offered by mining company to communities, environmental considerations, education, economic factors, provision of basic services, transportation and communication, support for social organizations, and social-health-related aspects. This research endeavors to provide a comprehensive understanding of the complex dynamics surrounding mining activity satisfaction among the indigenous population, offering a basis for further exploration and policy development.

Feb 17, 2024

By N. Coulson, P. F. Stewart

The Mine Health and Safety Act No. 29 of 1996, as amended, embeds an occupational health and safety management system that facilitates communication between representatives of the state, capital, and labour. In underground mines, two communication loops between these role players serve to separate the production chain of command from the political tripartite relations. Worker-elected health and safety representatives are involved in both communication loops, but are severely constrained in escalating their occupational health and safety concerns to the legalpolitical level. This has a direct bearing on the exercise of the Right to Refuse Dangerous Work (RRDW). As previously reported, health and safety representatives were found to primarily consult their production supervisors in preference to their trade-union representatives. This follow-up article presents production supervisor perspectives on the RRDW. The study demonstrates how, for mineworkers, the two distinct communication subsystems constrain, rather than facilitate, implementation of the RRDW.

Apr 14, 2024

By Itavahn Alves da Silva, Jose Dimas de Arruda, Amanda Aparecida Fátima Arruda, da Silva de Souza, Carlos Antonio da Silva, Varadarajan Seshadri, Samuel

The knowledge of the flow field inside a continuous casting mold is essential to improve operational efficiency of the process and also to achieve better inclusion control. Physical modeling, PIV technique and CFD have been employed to assess the velocity distribution in the metal- slag interface region in a slab mold. The analysis of results shows how higher casting velocity and lower immersion depth of submerged nozzle can lead to higher turbulence in the slag-metal interface. The effects of density difference between slag and metal and interfacial tension between the phases have been highlighted.

Jan 1, 2016

By F. E. Harris

It has been said that carbon is "ubiquitous" with reference to iron alloys. Certainly at temperatures where carbon and iron form the solid solution, austenite, it may be readily added to, or removed from, steel surfaces. Differences in concentration potential are the sole requirements for carbon flow. To measure the rate of carbon flow, a proportionality factor, D, is arbitrarily expressed in units of (length)2 X (time)-'. If the term used for carbon concentration is weight Pet C, as is customary, then a factor must be found, changing this term to One of weight Per unit volume when the diffusion coeficient, D, is used in flow formulae. The determination of D values for carbon is complicated since D varies with the concentration itself. The Matano method has often been employed for systems involving a variant D. This method expresses all evaluation of unsteady flow whereby D is given a relationship with the numerical value of C-x slopes. The author contends that this solution is incorrect, except when D is invariant. The primary purpose of this paper is to support this contention. Here diffusion is controlled under two conditions of flow. The first part deals with the steady state; the second part considers unsteady flow under definite restrictions. Beginning with the fundamental concept, the development is continued until equations for C-x curves are obtained. The solution is then subjected to experimental data. It is realized that a great amount of reliable data is required for a rigorous proof. KO such research is claimed. Instead an attempt is made to set forth the physical significance of the diffusion mechanism, and particularly to express the factors which influence the flow of carbon in austenite. Of equal significance is the implication that gaseous media may be employed with reasonable accuracy in making these determinations. The Steady State Diffusion of Carbon in Au~tenite The fundamental experiment defining diffusion in solid metals may be readily performed for carbon in gamma iron.' For this experiment a thin plate of medium carbon steel is chosen. The surfaces of this plate may be taken as two parallel planes which may be considered infinite for points well in the Center of the planes. These two planes are held at different concentrations of carbon at a constant temperature. This temperature, 1700°F for example, is one where the single phase: carbon in solution with gamma iron, exists. When these conditions are held for a sufficient time the concentration of carbon of the different points of the solid ment down towards its steady state value. At points well removed from the ends, the concentration will remain the Same along planes parallel to the surfaces of the plate.

Jan 1, 1948

By F. E. Harris

It has been said that carbon is "ubiquitous" with reference to iron alloys. Certainly at temperatures where carbon and iron form the solid solution, austenite, it may be readily added to, or removed from, steel surfaces. Differences in concentration potential are the sole requirements for carbon flow. To measure the rate of carbon flow, a proportionality factor, D, is arbitrarily expressed in units of (length)2 X (time)-'. If the term used for carbon concentration is weight Pet C, as is customary, then a factor must be found, changing this term to One of weight Per unit volume when the diffusion coeficient, D, is used in flow formulae. The determination of D values for carbon is complicated since D varies with the concentration itself. The Matano method has often been employed for systems involving a variant D. This method expresses all evaluation of unsteady flow whereby D is given a relationship with the numerical value of C-x slopes. The author contends that this solution is incorrect, except when D is invariant. The primary purpose of this paper is to support this contention. Here diffusion is controlled under two conditions of flow. The first part deals with the steady state; the second part considers unsteady flow under definite restrictions. Beginning with the fundamental concept, the development is continued until equations for C-x curves are obtained. The solution is then subjected to experimental data. It is realized that a great amount of reliable data is required for a rigorous proof. KO such research is claimed. Instead an attempt is made to set forth the physical significance of the diffusion mechanism, and particularly to express the factors which influence the flow of carbon in austenite. Of equal significance is the implication that gaseous media may be employed with reasonable accuracy in making these determinations. The Steady State Diffusion of Carbon in Au~tenite The fundamental experiment defining diffusion in solid metals may be readily performed for carbon in gamma iron.' For this experiment a thin plate of medium carbon steel is chosen. The surfaces of this plate may be taken as two parallel planes which may be considered infinite for points well in the Center of the planes. These two planes are held at different concentrations of carbon at a constant temperature. This temperature, 1700°F for example, is one where the single phase: carbon in solution with gamma iron, exists. When these conditions are held for a sufficient time the concentration of carbon of the different points of the solid ment down towards its steady state value. At points well removed from the ends, the concentration will remain the Same along planes parallel to the surfaces of the plate.

Jan 1, 1948