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By MOHAMED WAEL, ANASTASIA GOEVA, ABDULAZIZ TAWFEEQI, IHTISHAM TARIQ, S. M. ZAKIR HOSSAIN, NIAZ ALI KHAN, MUHAMMAD FAISAL IRFAN

Carbon capture and storage (CCS) is an attractive area of research in such fields as CO2 mineral carbonation, global warming and sustainable energy systems. In this study, carbonation efficiency for aqueous mineral carbonation (MC) was achieved through two steps,which include leaching of calciumfrom cement kiln dust (CKD) followed by the reaction of pure CO2 with the calcium hydroxide precipitates formed by the hydroxylation using NaOH. Response surface methodology (RSM) with a Box-Behnken design (BBD) was applied to optimize the calciumleaching yield,while the carbonation efficiency from CKD was assessed using RSMwith central composite design (CCD). Optimization of calcium leaching is highly important, as it is a rate-limiting reaction step in MC and also influences and enhances carbonation efficiency. Different parameters including acid concentration (HNO3), leaching temperature, leaching time, and dose of CKD sample were considered in order to optimize the maximum yield of Ca leaching from the CKD sample. In addition, different CO2 flow rates and temperatures were used as parameters for optimizing carbonation efficiency. Two quadratic regression models were developed for each process, i.e. calciumleaching and carbonation. For calcium leaching, a maximum of 98.55% calcium was extracted under the optimal set of acid concentration 4.13 M, 90 °C, 28 min leaching time, and 13.8 g of CKD sample. For carbonation, the maximum carbonation efficiency of 89.2% was achieved for a CO2 flow rate of 1163 cm3/min at 90 °C. Calcium leaching results indicate that the leaching yield was significantly affected by all the input parameters except leaching time. For carbonation, both factors affected the carbonation efficiency, with the effect temperature shown to be greater than that of the CO2 flow rate. Additionally, the predicted results agreed well with the experimental values for both calcium leaching and carbonation processes, with errors of less than 1% and 5%, respectively.

Jun 5, 2020

By J. L. Sloughfy

The size distribution and mechanical strength of the iron ore pellet burden are important parameters in determining the efficiency of the blast furnace. From the very outset, the guiding principle of our pellet quality improvement program was that these parameters are also the key to improving productivity and cost control at the pellet plant. Recognizing the need for improved blast furnace burdens and for higher productivity and lower costs at the pellet plant, Carol Lake operators, in conjunction with the IOC Pellet Quality Committee, established the following goals for the improvement of Carol pellets: [ ]

Jan 1, 1981

By I. Iwasaki

A low-grade copper-nickel deposit, with an estimated size of 4.6 billion tonnes and with average analyses of 0.6% copper, 0.2% nickel, occurs in northeastern Minnesota. In addition to copper, nickel, cobalt, and precious metals, the Duluth gabbro contains magnetite, ilmenite, olivine, plagioclase and biotite. It is estimated that the flotation tailings that would be produced by a concentrator of optimal size to sustain a smelter would amount to 20 million t per year. The flotation tailings, having already been ground, warrant a closer examination for the recovery and utilization of potential by-products. The residual sulfide minerals and fibrous minerals may also be isolated and treated separately for useful purposes or for disposal in an environmentally acceptable manner. Two flowsheets were developed; one involving preconcentration by low- and high-intensity magnetic separation and another involving preconcentration by gravity concentration. The concentration methods for recovering and purifying individual by-product minerals were investigated. From their chemical, physical and mineralogical characteristics, the potential areas of application and marketabilities of each product fraction were surveyed.

Jan 1, 1983

By J. Kretschmann, H. Mischo, O. Drusche, S. Krause

Mining is and will be inevitable in spite of the increasing implementation of circular strategies. The energy transition and population growth will boost the demand for critical raw materials. It is the opportunity for miners to reinvent their business models. Generating attractive new business cases with sustainability-oriented innovations meets investor and stakeholder expectations from the beginning. This contribution guides managers on their pathway towards sustainable success. Contextual sustainable business model patterns will be presented that can be adjusted individually, regardless of actor’s size. It will also point out, how sustainable value creation can be measured on business model level.

Feb 1, 2023

By Werner Wenzel

Whisker growth during the reduction of iron ores The phenomenon of whisker growth can be observed in a number of solid-state crystallisation reactions, which, apparently, appear in6 the first instance as though they are two independent processes. From such reactions, one can find the whisker type of crystallisation on solid bodies. These examples show, that the whisker growth is neither due to certain crystal forms with predetermined temperature and pressureranges, nor to parameters, which, ad hoc, are necessary for the crystallisation. In all cases the whisker formation seems to depend on nucleation and the availability of crystallizing material in direct environment of such a nucleus, under given parameters of a system. One can generally state, that the research of whisker growth with the aim of establishing proper physical laws, to determine the foundamentals of whisker formation and whisker growth, is at present under active study. We can conclude that, although a great number of hypothesis have been proposed; no concluding theory has yet been arrived at. In the institute for ferrous metallurgy of the technical university of Aachen, research works are undertaken to find an explination to various metallurgical phenomena through help of whisker growth which was observed under varying conditions of iron ore reduction. This was possible by using refined microscopic techniques through which the whisker growth on solid oxyde substrates is detected. This refined technique combines the latest methods of surface examination with the help of stereo-scan-electron-microscope and proper and carefull preparation of surface to be stereo-scanned.

Jan 1, 1971

By Jagannath Pal, Ammasi Ayyandurai

Hematite ore pellets require a much higher induration temperature than magnetite ore pellets because no exothermic heat is generated due to oxidation inside during induration-like magnetite pellets. Carbon is used as in situ heat source in hematite ore pellets which can reduce temperature requirement in the induration strand and hence decreases energy consumption. Many investigators have reported that a 0.8–1.25% addition of carbon in hematite pellets can improve the pellet properties also. However, to investigate the exact role of carbon in hematite pellets, its reaction mechanisms and kinetics study are required which have not been done so far. Therefore, the reaction mechanism and its kinetics have been studied in this investigation. It has been found that carbon reaction happens in pellets from the surface towards the center in a topochemical manner which is controlled by pore diffusion of gas, and its activation energy is around 52 k J mol− 1. It is also found that apart from in situ heat, carbon in hematite pellets enhances diffusion bonding which improves pellet properties. This study ascertains the exact role of carbon in hematite pellets which may help operators to use carbon effectively to reduce energy consumption and improve pellet properties.

Nov 6, 2022

By Cem Şensöğüt, Özer Ören, Yaşar Kasap

The mining sector, which has an important place in terms of raw material and energy supply, is referred as a sector with one of the highest fatal accidents in comparison with other sectors. In this century, where occupational health and safety awareness has increased, it is important to review the past accident statistics and to determine the current deficiencies by using the information in the inventory. In this study, the Malmquist total factor productivity index (MPI) has been utilized to investigate the changes in the work accidents occurring in the Western Lignite Corporation (Turkey), where underground and surface production methods are applied, and to determine the measures to be taken. According to the results obtained, both the decrease in production amount and the increase in the number of accidents caused inefficiencies during the period in concern due to the expected 10-year economic life of the mechanized system operating in the underground production panel that came to an end in 2007 and the flooding took place in early 2017. Compared with the underground operations, it has been determined that production can be carried out at the appropriate scale despite the heavy working conditions encountered due to the changing climatic conditions and the progress of production in the surface operations.

By I. E. Perera

Experiments were conducted to evaluate the response characteristics of commercially available gas, smoke, and flame sensors to fires of common combustible mine materials. The experiments were conducted in the large-scale Fire gallery located at the National Institute for Occupational Safety and Health (NIOSH) Lake Lynn Laboratory (LLL) in Fairchance, PA, using Ponderosa Pine, Red Oak, Douglas-fir, high and low volatile coals, PVC and SBR conveyor belt, No. 2 diesel fuel, and diesel exhaust. All the experiments (except those using No. 2 diesel fuel and the diesel exhaust tests) were conducted in a similar manner, with combustible materials heated rapidly by electrical strip heaters producing smoldering fires that quickly transitioned into flaming fires. The sensors included a diffusion-type carbon monoxide (CO) sensor, photoelectric- and ionization-type smoke sensors, a video smoke/flame detector, and an optical flame detector. Simultaneous measurements were obtained for average gas concentrations, smoke mass concentrations, and smoke optical densities in order to quantify the levels of combustion products at the alert and alarm times of the sensors. Because the required sensor alarm levels are 10 ppm and 0.044 m-1 optical density for CO and smoke sensors, respectively, the different sensor alarms are compared to the time at which the CO and smoke reached these alarm levels (1). In addition, the potential impact of using smoke sensors that have met the performance standards from accredited testing laboratories is also evaluated using the response of an Underwriters? Laboratory (UL)-approved combination photoelectric/ionization smoke detector. The results are discussed relative to fire sensor needs that can have a positive impact on mine fire safety.

Jan 1, 2012

By R. N. Gow

EH-pH diagrams are useful tools in understanding how mineral surfaces react in solution and particularly how aqueous conditions can be changed to enhance mineral leaching processes. However, successful application of these diagrams requires several things be kept in mind to prevent what others have termed ?gross errors? in their calculation and use. The aqueous Cu-S system is used as the basis for explaining the mass-balanced method of calculating EH-pH diagrams with the thermodynamic equilibrium software, STABCAL. This includes a breakdown of the Gibbs? Phase Rule and how it is employed in STABCAL to modify the diagrams. This methodology was then applied to the aqueous Cu-As-S system and resulting diagrams are compared against examples of those generated using the predominant-ion method. The resulting mass-balanced diagram for enargite (Cu3AsS4) is noted to compare well with spectroelectrochemical measurements using Raman spectroscopy and cyclic voltammetry.

Feb 23, 2014

By X. Wang, Y. Luo

The propensity of coal spontaneous combustion can be evaluated using various laboratory testing methods, such as R70 adiabatic tests, thermal gravimetric analyzer (TGA) tests and critical self-heating temperature (CSHT) methods. Each of the methods has its unique characteristics and index for classifying the propensity of self-ignition of coals. Accountable relationships among the propensity indices of different methods should be established. Using the newly established R70 and TGA testing setups in our ventilation laboratory, samples from U.S. coal mines have been collected and tested. The TGA is a relatively new quantitative method. A test can be conducted in a relatively short time, within about one and a half hours, compared to the adiabatic tests. The temperature and weight of the sample can be measured with high precision and then used to determine the activation energy of the coal, which is a good indicator of the potential for self-heating. Under a specific experimental design, the TGA technique could perform the proximate analysis for determining coal quality parameters (e.g., moisture, volatile matter, fixed carbon and ash content). These parameters can be used in an empirical equation for assessing the potential for coal self-ignition. The trend of activation energies determined using TGA techniques is reasonably consistent with the trend of activation energies determined using adiabatic tests. As a case study, a comparative analysis of these two methods for determining activation energy was made on coal samples collected from Indiana. The kinetics of the spontaneous combustion mechanism has been explained. If the functional groups of a coal such as hydroxyl (-OH), carboxyl (-COOH), methyl (-CH3), etc., activate more easily with a small amount of activation energy at a relatively low temperature, the coal will have a higher potential for self-heating. With the kinetic and coal quality parameters determined by the TGA setup, it has been found that the coal with a low potential for self-ignition has low self-heating rate, a high activation energy and a high minimum self-heating temperature.

Jan 1, 2012

By Verya Nasri, Mehdi Bakhshi

The development of the Montreal metro extension Line 5 -Blue Line- toward the northeast are located between the existing Saint-Michel station and Anjou. It consists of 6-km long two-track tunnel, five new stations and six auxiliary structures. Most of the tunnel (5.5 km) will be excavated by a 9.6 m diameter shielded rock TBM and supported by a precast segmental lining system. TBM will be fitted for probing and preexcavation grouting to control water inflow into the tunnel during the excavation. This paper presents major design aspects of the TBM tunnel including alignment, geological condition, spaceproofing, precast segmental lining, and geotechnical instrumentation and monitoring.

Dec 1, 2022

By W. M. Hart

The current Automatic Data Acquisition system developed by some support manufacturers makes it possible to continuously monitor and record changes in leg pressure and advancing ram stroke in every shield, and shearer position at any moment during the mining operation. In order to effectively use the massive data obtained from this system for improving production and maintenance managements as well as providing better roof control at a longwall face, the research currently conducted jointly by West Virginia University and Cyprus-Amax Coal Co. attempts to develop a Longwall Management System for mine operators. The LMS software package runs on a MS Windows NT environment and consists of four sub-systems: (1) Data Interpretation and Analysis; (2) Production Management; (3) Maintenance Management; and (4) Ground Control. This paper presents the details of each sub-system.

Jan 1, 1995

By B. Mishra, Q. Shi

Numerical simulations have been used to investigate roof fall in the past decades. Comparing to the continuum based methods, the discrete element method has been well recognized for its excellent performance in simulating large strain problems and fracturing processes in the rock mass. However, the discrete element method has its limitations. When simulating a large-scale problem, a large number of particles are required, which consumes significant computational resources. In the present study, a 3D numerical model coupled with the finite-difference method (FDM) and the discreteelement method (DEM) was created to simulate the laminated roof failure in an eastern coal mine in the US. In the FDM-DEM coupled model, the laminated roof of the entry is represented by an assembly of bonded particles using PFC3D. The laminated roof is simulated by adding parallel discontinuities. The discontinuities are given certain stiffness and strength in the model. The ribs, floor, and far-field surrounding rock are represented by continuum zones using FLAC3D. The strength of the discontinuities is varied sequentially and the fracturing of the laminated roof was analyzed with respect to entry advance. The results showed that the laminated roof fractures along the discontinuities while an intact roof fractures in a dome shape. Increasing the strength of discontinuity could enlarge the tensile zone inside the laminated roof and hence change the crack distribution. In addition, the crack quantity in the laminated roof behind the advancing face decreases with the increment of discontinuity strength while this trend is not occurring ahead of the advancing face. The simulation demonstrated that coupled method using PFC3D/FLAC3D can reproduce the laminated roof failure in underground coal mines.

Mar 2, 2022

By D. A. Shock

Utilizing the technology developed for oil well stimulation by hydrofracing, a disposal system which permanently fixes the waste has been proven. Large quantities of radioactive waste can be processed by a single well system making this method an attractive method for permanent radioactive waste disposal. The system depends on locating a relatively thick formation of impermeable, but easily fracturable rock such as a shale, creating a horizontal fracture, pumping the waste into the fracture in a form which will subsequently solidify and seal the fracture from the well system. The paper presents the theoretical considerations from creating and extending horizontal fractures and how these considerations were used in designing a waste disposal system which is now operating.

Jan 1, 1964

By Arthur P. Nelson

In opening, I want to thank the program committee and members of the Society of Mining Engineers of AIME for the opportunity to speak to you. Various chapters of AIME this past year have expressed interest in the Federal Metal and Nonmetallic Mine Safety Act. We want to see that interest continue, because the reason for the legislation was the safety and health of the industry's workforce. The Department of the Interior was directed by the Congress to administer the provisions of the Act and is therefore held directly accountable for the success or failure of its intent. We intend to see it succeed. Among other things, the Act does provide for education and training under Section 15. This provision has been implemented and is expanding. However, the responsibility of my office is inspection and enforcement and that is my subject today.

Jan 1, 1973

By Maral Malekian, Pat Bellett, Eranda Tennakoon, Fernanda Carrea, Moe Momayez

Slope instabilities in open-pit mines pose a safety risk to workers and a financial burden on production. The direct impact of slope stability on safety and production makes slope failure predictions one of the important challenges in the mining industry. Predicting the precise time of slope failure has been the subject of much research in conjunction with the development of innovative monitoring technology designed to prevent sudden failures. This paper investigates the use of AutoRegressive Integrated Moving Average (ARIMA) model to predict the time of slope failure. Input data such as inverse velocity (IV) and dimensionless inverse velocity (DIV) from 20 slope failures were used to train the model predict the failure time. For comparison purposes, the time of slope failure using the traditional inverse velocity method is also provided. We show that ARIMA provides 90% more accurate predictions than the TIV approach.

Jul 12, 2023

By N. L. Wesis

General History The first jaw crusher in the US was patented about 1830, but the Blake crusher that has maintained a substantial advantage over other types was invented in 1858 by Eli Whitney Blake. For going on 150 years the jaw crusher has been an invaluable machine; even today, when gyratory crushers have assumed most of the burden of crushing large tonnages of large rock and ore, the jaw crusher has a firm place in the mining industry. It is interesting that soon after the invention of the Philetius Gates gyratory crusher in 1881, a contest between the first No. 2 Gates and Blake jaw crushers of equal gape showed the gyratory to be 3.2 times as fast. This foretold a day not far in the future when the jaw crusher would not be adequate on the largest jobs. In his Textbook of Ore Dressing (1909) R. H. Richards recom¬mended that the word breaker be used for all machines breaking to relatively large sizes (say to 5 in. or greater), and crusher be used for finer work. Even in the 1968 US Bureau of Mines dictionary of mining terms the work breaker is defined by Richards in this context. However, in modern US usage it is nearly limited to coal breaking. Over the years the jaw crusher has been developed in a variety of forms but it appears today in these three general forms: (I) Blake type, (2) Dodge type, and (3) single toggle (or overhead eccentric) type. All of these crushers have a fixed jaw and a moving jaw, between which the coarse rock fragments are intermittently caught and crushed. The three types are differentiated by the manner in which the movable jaw is moved in relation to the fixed. Types The Blake-type crusher is shown in cross section in Fig. 1. The simplicity and strength that have made it first among jaw crushers are evident. The movable jaw is suspended from a cross-shaft at its upper end, this shaft being carried in bearings on the sides of the frame. The actuating mechanism consists of an eccentric shaft, also supported in frame-mounted bearings, which imparts through a pit¬ man and a pair of toggles a reciprocating motion to the bottom of the swing jaw, the return movement being effected by several spring¬loaded rods. The whole is built into a box frame with the crushing chamber at one end. As in all jaw crushers, the eccentric shaft is equipped with a heavy flywheel that maintains an even speed through¬out each stroke. The Dodge-type crusher illustrated in Fig. 2 is simple, mechani¬cally. Its movable jaw, being pivoted below the discharge opening, has minimum movement at crusher discharge and maximum at crusher feed. Because the choke point coincides with the point of least motion, these crushers are of relatively low capacity, and the rapid action in the feed area gives the machine the advantages of large reduction ratio and closely sized product. Thus, it fits well into low-capacity operations like sample reduction. Besides low capacity, its principal disadvantages are tendency to pack and make fines. The single-toggle or overhead-eccentric type of jaw crusher (see Fig. 3) has gained in usage, starting as a modification of the Dodge idea in that the greatest movement of the movable jaw occurs at the top, and being gradually improved and strengthened to its position today where it covers just as wide a field of application as the Blake type from the standpoint of feed opening. The motion of the movable jaw is the result of the circular motion of the eccentric shaft at the top of the swing jaw combined with the rocking action imparted to the bottom by the inclined toggle plate. Because of light weight and mechanical simplicity, it is economical in small mills and portable plants where the rock is not as tough and abrasive as to punish the machine with excessive impact from shocks, or excessive wear result¬ing from the pronounced vertical component of motion.

Jan 1, 1985

By C. V. Deutsch, D. A. Silva

The geologic modeling of multiple domains is required for the prediction of mineral resources and reserves. In general, explicit methods have wide acceptance among modelers due to the ability to manually add deemed important trends and geological features into the models. As an alternative, implicit geologic modeling techniques are increasingly adopted to reduce professional time requirements. These methods aim for objective, repeatable and flexible models by replacing the manual time-consuming interpretation of sections with the interpolation of signed distance values. These techniques, however, have been developed for the binary case of two domains at a time. The current paper presents an algorithm that extends the binary case to multiple domains. The method is able to transfer large-scale geological features from data to geologic models. A case study illustrates the benefits of the algorithm and practical implementation considerations.

Jan 1, 2016

By Isabel F. Barton, MarkD. Barton, Christian A. Rathkopf

Molybdenite is the world’s principal source of rhenium (Re), a critical element in multiple high-tech applications. However, the Re contents in molybdenite vary by orders of magnitude on scales ranging from single grains to whole deposits. In order to better understand the systematics of this variation and what geochemical factors control molybdenite Re concentration, and hence overall Re resources, we examine global patterns in molybdenite Re contents through a compilation of > 3000 measurements of Re in molybdenite from > 700 mainly ore-bearing moderate- to high-temperature hydrothermal systems of different types. Our results are similar to but expand on those of earlier studies. Rhenium concentration in molybdenite has a lognormal distribution and varies systematically with type of geologic system, intrusive lithology, and Mo grade. The lowest-Re molybdenite occurs in greisens (geometric mean 1 ppm ± a multiplicative standard deviation of 9), quartz vein-hosted W-Sn deposits (2 ± 5 ppm), unmineralized granites and granodiorites (12 ± 8 ppm), intrusion-related deposits (24 ± 8 ppm), and porphyry W-Sn deposits (16 ± 11 ppm). Rhenium is most enriched in molybdenites from volcanic sublimates (23,800 ± 5 ppm), with skarn Fe and Au (560 ± 5 ppm and 540 ± 3 ppm respectively) and porphyry Cu and Cu-Au deposits next (470 ± 4 and 430 ± 7 ppm respectively). Among porphyries, skarns, and quartz vein-hosted deposits, Re is most highly concentrated in molybdenites from Cu and Au systems and its concentration decreases systematically through Cu-Mo, Mo, Sn, and W deposits. In nearly all cases, molybdenites from systems associated with intermediate igneous rocks contain more Re than molybdenites from systems of the same type with more felsic rock associations. The disparity between Re contents of molybdenite in felsic and intermediate systems is largest for porphyries, quartz vein-hosted, and skarn deposits and is near zero for subeconomic or barren granite and granodiorite Mo systems; felsic intrusion-related deposits have slightly higher molybdenite Re than their equivalents associated with intermediate intrusions. In most systems, molybdenite Re content does not correlate with metal grade, but may have an inverse correlation with Au grade in intrusion-related deposits (based on a small number of data points) and does exhibit a strong inverse correlation with deposit Mo grade. Dilution of Re through larger amounts (higher deposit grades) of molybdenite explains about 40% of this correlation, but the relative enrichment of Re in molybdenite from low-Mo deposits must also reflect some selective enrichment of Re/Mo in porphyry Cu systems compared to porphyry Mo systems. We found no evidence for secular increase or other systematic temporal variation in molybdenite Re content. The data regarding the use of molybdenite Re content as a proxy for mantle influence are ambiguous. Nearly all observed empirical correlations can be traced back to differences in redox state and sulfide concentration, the two geochemical factors identified here and by previous experimental work as the controlling influences on Re mobility under hydrothermal conditions. Hydrothermal systems with reducing conditions (W- and Sn-rich) tend to have low molybdenite Re even though compiled whole-rock data indicate that their source rocks have as much or more Re as those of more oxidized systems (e.g., Cu-rich). Vapor-phase exsolution, crustal assimilation, and mixing with external fluids may all enrich molybdenite Re concentrations in individual deposits and deposit types, but their extent and importance in overall hydrothermal concentration of Re is uncertain. Thus, it appears that the available molybdenite Re resource in an ore deposit largely depends on how the deposit’s redox and sulfidation conditions have varied over time and space during the timespan of hydrothermal activity. Oxidized, high-sulfide conditions tend to concentrate Re in molybdenite, whereas reducing conditions tend to leave Re dispersed at low concentrations in the bulk rock.

By Neel Gupta, Brijes Mishra

Coal mining activity disturbs the natural equilibrium of in situ stress state such that the induced stresses deform the surrounding rock mass. Although the installation of roof supports typically prevents rock deformation, rock mass failure may still occur in bolted roof. The erratic failure of rock mass after few days to months and years of excavation is the result of time-dependent deformation of roof rock under constant surrounding stresses. In the current research, the triaxial laboratory creep experiments proved that Marcellus shale exhibits time-dependent deformation under constant stress that was smaller than the failure strength. However, unlike conventional experimental results, the time-dependent deformation did not depend on the level of constant stress. The often-neglected initial state of specimens and intrinsic heterogeneity highly influenced the time-dependent failure of Marcellus shale.

Jul 27, 2021