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By W. Irwin

As a consequence of the oil crisis of the 70?s, the commercial value of coal increased very sharply and an upward trend in coal prices although now less pronounced, continues today. The graph shown in figure 1 illustrates the trend in the F.O.B. price of U.S. metallurgical coal. This trend occurs during a time when mechanized mining is firmly established as a means of production throughout the coal mining world. With modem methods of mining, mechanical cleaning is a necessity and quality control is no longer entirely dependant upon coal face practice. The efficiency of fine coal recovery is of vital economic importance to present day operations and good practice in this field contributes significantly to improving profitability. Numerous processes are available for the duty and this paper discusses one such system, namely the practice of froth flotation.

Jan 1, 1980

By F. L. Pirkle

A heavy mineral deposit about 1.6 km (1 mile) in length, 0.13 km (0.08 mile) in width and averaging about 3 m (10 ft) in thickness is exposed approximately 130 km (80 miles) east of Denver, along Interstate 70, in Elbert county, CO near the town of Limon. The deposit is exposed in a geomorphic feature known locally as Titanium ridge. The dominant heavy minerals, accounting for about 70% of the total heavy-mineral suite by weight, are ilmenite, garnet and zircon. The mineralized zone appears in a series of visually interpretable facies that are stacked vertically and represent subtidal, forebeach, backbeach, washover fan and aeolian depositional environments. These paleoenvironments are analogous to depositional environments represented by a modern heavy-mineral bearing facies tract on St. Catherines Island, Ga. Thus, Titanium ridge provides evidence that heavy-mineral accumulation models for late cenozoic deposits in the Georgia and Florida coastal plains are applicable to heavy-mineral deposits of the Western Interior subsurface and, by implication, the Western Interior Seaway, extending from Mexico to the Canadian Arctic.

Jan 1, 2012

By S J. Neethling and, S J. R Simons

In this paper the effect of humic substances (natural surfactants), electrolytes and solid particles on bubble coalescence, and as a consequence on froth stability, have been investigated. In this study two bubbles of equal size were formed and forced to collide using a novel experimental apparatus. The interactions were recorded by a high-speed camera, the images of which helped to determine the coalescence frequency and the coalescence time, as well as the mechanisms of the interactions. Two types of humic substances were used, along with three different electrolytes. Humic substances appeared to have a considerable effect on bubble coalescence, while the effect of electrolytes was minimal. Moderate and high hydrophobic glass spheres were used between two bubbles. Very hydrophobic spheres promoted fast bubble coalescence, while moderate hydrophobic spheres had no effect. Data of coalescence frequency and time is presented, as well as images of the coalescence events. The coalescence frequency was used to validate a parameter, Pf, known as the film failure frequency, used in a simulation model to predict foam height in a gas-sparged vessel. Predictions determined using Pf were then validated by experimentation.

Jan 1, 2005

By Christopher R. Harris

"Considerations are presented for developing and implementing self-hardening slurry mix designs to be utilized in barrier seepage walls. Slag-cement-cement-bentonite (SCCB) slurries are the primary focus, with some comparisons referenced to the more traditional Portland-based cement-bentonite (CB) slurries. Field and laboratory mixing methods are reviewed, including 1) single sack – single mixer method; 2) bentonite slurry mixer – cementitious addition mixer method; 3) bentonite mixer – grout mixer – CB blending mixer method. Major phenomena associated with the dynamics of barrier wall excavation, such as loss of water from the in-trench slurry and consolidation of in-trench slurry are discussed. Other topics touched upon include sand content effects, fluidizers utilized, and chemical contaminants. The role of higher bentonite to water ratio is reviewed, with demonstration of improvement of filtration properties, and an increase of water retention of the final consolidated product.IntroductionSelf-hardening slurry has been utilized to construct barrier seepage walls for many decades. This is essentially a single-step slurry excavation and backfill process whereby the trench-supporting fluid gains strength over a short period during installation and maintains or develops low hydraulic conductivity. The resulting curing slurry becomes the actual barrier wall as the resultant cement-augmented clay slurry now fulfills the dual purpose of both temporary trench stabilization and final cured-in-place product. This eliminates the requirement and expense of subsequent backfill/slurry displacement operations required in traditional barrier wall installations.Self-hardening slurries have been fabricated using a number of various clays, most commonly sodium bentonite, calcium bentonite, attapulgite, and sepiolite. Perhaps due to plentiful high quality sodium bentonite deposits found domestically, the proven excavation stabilization properties imparted from sodium bentonite slurries, sodium bentonites are typically specified for formulating self-hardening slurries in the US. Cementitious materials utilized most commonly are Portland cement and slag (ground blast furnace slag or GBFS). For the purposes of this discussion, self-hardening slurry having a cementitious of Portland will be referred to as CB. Those having cementitious material of GBFS replacing Portland (partially or wholly) will be referred to as SCCB."

Jan 1, 2016

By AIME AIME

THE 130th Meeting of the Institute was held in Birmingham on Oct. 13 to 15, with visits to other mines and districts before and after. The last visit of the Institute to Birmingham was made in 1888, thirty-six years ago, and vast development has been made in' the district since then. With proverbial southern hospitality compounding over this period of years the welcome given to the Institute was such that .it is difficult to express properly the gratification and appreciation of the visiting members and the officers of the Institute. The Birmingham News in an editorial said: Birmingham is duly appreciative of the presence of these gentlemen, not because they are all distinguished in their great services in the mining and metallurgical world, but for the further reason that our interests are very largely wrapped up in their deliberations. Birmingham is one of the great industrial centers of America. Their discussions are of vital concern to all of us.

Jan 1, 1924

By Yiming Sun, John Stolz, Jakob Walter, Drew Mason

The Courthouse Commons SEM Tunnel was excavated within 6 feet of cover beneath two buildings in downtown San Diego utilizing high-precision geotechnical instrumentation. The excavated dimensions are approximately 25 feet in diameter and 328 feet in length connecting two in-service detentionlevel security buildings. Presupport includes large-diameter grouted canopy pipes and smaller pipe spiles. Initial support consists of fiber-reinforced shotcrete with lattice girders. This paper presents observed ground and structure behavior and lessons learned. During construction an unanticipated brick structure was encountered, and methods were developed to improve adhesion of shotcrete to sandy soil and to reduce rebound

Dec 1, 2022

By C. A. Heiland

IN the third year of war, geophysical oil exploration broke all records to keep pace with the demand for increased reserves. Geophysical prospecting for strategic and other minerals also grew in scope. The trend of geophysical oil exploration throughout the war is indicated in Fig. 1. This figure resembles the one presented in the last annual review issue of M&M (February 1944, p. 62), corrected for data on-operations in the last months of 1943 and extended into 1944. The average number of geophysical oil prospecting crews in the field in 1944 was 451, whereas the total in 1943 was 340. An upward trend in the use of all geophysical methods is clearly evident throughout the year. Seismic operations were 67 per cent, gravimeter surveys 28 per cent, and other methods 5 per cent of the total. Seismic reflection and refraction crews increased 181/2 per cent over the 1943 average, gravimeter operations increased 73 per cent, and other methods gained 92 per cent. The increase in seismic and gravimeter operations, particularly the latter, is probably due to an increased production of equipment and the organization of new service companies. Miscellaneous methods gained largely through a revival of magnetometer work, and an increase in the use of torsion balances and electrical equipment. In comparison with the prewar average of 1941, it is noteworthy that seismic operations increased 58 per cent, gravimeter operations 88 per cent, and miscellaneous other methods gained as much as 283 per cent. Unfortunately the expansion in the number of geophysical crews does not indicate a proportionate increase in efficiency or in areal coverage, as will be brought out later.

Jan 1, 1945

By Sherwin F. Kelly

THIS is intended as a simple review of the principles and practice of geophysics, so will not be of interest to the geophysicist, who is hereby warned of its elementary character. The engineers for whom it is written are those who, having glimpsed the formidable formulas and discussions of the geophysicists, give all publications on the subject a wide berth. For a few years now the geo-physicists have had a tendency to be ingrowing at their meetings, going deeper and deeper into theory and instrument construction, and forgetting to present the topics that would interest the practicing engineer who desires merely to know how geophysics can help him, not why.

Jan 1, 1934

By R. Mensah-Biney

The aqueous biphase separation process (ABS) has been used to separate ultrafine industrial minerals. The partition behavior of TiO2, Al2O3, Fe2O3 and kaolin was not pH dependent. The partition behavior of SiO2 was, however, pH dependent. The partition coefficient of kaolin in PEG 3400/ Na2CO3 biphase system was = 150 and that of the silica in the same system was = 0.02, resulting in a separation factor of = 8500 between kaolin and silica. The aqueous biphase separation system was used to separate free silica from kaolin in a raw clay sample from Mexico. The partition behavior of mica, feldspar and clay from North Carolina was also evaluated.

Jan 1, 1999

By Muhammet Mustafa Kahraman

Despite technological advancements and organizational adjustments, lost time accidents are major issues in occupational safety. However, there is very limited work that focuses on variables influencing days lost as a result of occupational accidents. In this study, decision tree and artificial neural network methods were used as machine learning techniques to investigate the impact of factors on accident lost day duration. Degree of injury, worker age, and worker activity were found to be the top three variables impacting loss of time from work. It was also identified that the mining method, location, and nature of injury had a moderate influence on duration lost due to occupational accidents. However, worker experience and ore type did not have any significant impact on the duration, which is an unexpected result. These results confirmed that some accident factors that might have a large influence on the number of mine accidents can be less critical when it comes to accident lost day duration.

Feb 3, 2021

By Cícero Alberto Pereira Belém

Neste artigo, buscou-se replicar, em laboratório, os procedimentos de retificação do eixo propulsor, elemento responsável pela transmissão de força e potência para os hélices do Navio, e que, frequentemente, apresentam problemas de desgaste devido ao atrito entre o eixo e seus pontos de apoio (mancais). Em virtude do intenso uso deste tipo de transporte, é frequente a manutenção da linha de eixo dessas embarcações, havendo a necessidade de uma análise que verifique se os métodos utilizados seguem padrões normatizados e que passem por testes de qualificação. A relevância regional do estudo se justifica pelo potencial hidrográfico da Região Amazônica, a qual possui bacias como Solimões-Amazonas e Rio Madeira, que servem como vias de acesso e de transporte de pequenas, médias e grandes embarcações; seus afluentes são verdadeiras estradas fluviais, sendo um modal hidroviário de importância histórica e cultural. As operações em laboratório seguiram as etapas: soldagem dos Corpos de Prova pelos processos SMAW (processo mais utilizado na maioria das empresas de retificação de eixos na região Norte) e GMAW com dois métodos (automatizado e manual) e com adição de dois metais de solda diferentes (307, 309L com e sem adição de Nióbio); ensaio por Líquido Penetrante (LP), Metalografia, Análise Macrográfica e Micrográfica e Análise de Microdureza. Os resultados obtidos em laboratório demonstraram que a metodologia desenvolvida na retificação é apropriada e eficiente para a recuperação de eixos propulsores.

Oct 30, 2017

By T. Nesane, S. S. Mnyakeni-Moleele, L. C. Murulana

The effectiveness of two synthesized ionic liquids, 1-(benzyloxy)-1-oxopropan-2-aminium 4-methylbenzenesulfonate (1-BOPAMS) and 4-(benzyloxy)-4-oxobutan-1-aminium 4-methylbenzenesulfonate (4-BOBAMS), were evaluated for mild steel corrosion inhibition in 1.0 M hydro-chloric acid solution, using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and gravimetric techniques. Organic moieties responsible for the adsorption process on mild steel surface were investigated using Fourier transform infrared spectroscopy (FTIR). Gravimetric analysis revealed that the inhibition efficiency of 1-BOPAMS and 4-BOBAMS increased with concentration, with maximum inhibition values of 90.32% and 97.91%, respectively, at the highest concentration of the inhibitors. Gibbs free energy (ΔG°ads) values indicated a strong interaction between the mild steel surface and the molecules of the ionic liquids, and that the adsorption process was spontaneous. These values also show that the inhibitive nature of ionic liquids against mild steel corrosion is caused by a mixedtype of adsorption film formed on the steel surface. The Langmuir adsorption isotherm was used to describe the adsorption of ionic liquid molecules onto the mild steel surface. Polarization curves showed that 1-BOPAMS and 4-BOBAMS have a similar effect on both the anodic and cathodic half-reactions, indicating that they prevent the dissolution of mild steel through both physical and chemical process. Nyquist plots were defined by incomplete semicircle capacitive loops, showing that the charge transfer mechanism controls the corrosion of mild steel in acidic solution.

Apr 1, 2021

By S. Sekhar, S. Bhargava, A. K. Godugu, J. L. Porathur

Cemented backfilling has enabled underground hard rock mines to extract orebodies more safely with improved ore recovery. It is important to estimate the minimum required strength parameters for a backfill mix by optimizing the binder percentage to enable cost-effective and safe stoping operations. We conducted three-dimensional numerical modelling to study the effect of various stoping parameters on the stability of a free-standing backfill wall. A Mohr-Coulomb material model was used for the backfill material and the rock-fill interface. A strength reduction technique, excluding friction angle, was employed to arrive at a minimum stable strength value for the backfill. For a given combination of strength values, the stability state of the backfill wall could be demarcated using a displacement and yield zone tracking method. The numerical modelling results are compared to some earlier theoretical models. From the simulations, a predictive equation is developed to predict the required strength parameters for a backfill mix to ensure a stable free-standing wall. Examples are given of the successful use of the predictive equation at some underground hard rock mine sites in India.

May 2, 2022

By J. S. Contreras, E. Córdova, I. Gottreux, A. Anani, A. Ferrada

Cave mining is an underground mass mining technique. The largest projects, which are known as ‘super caves’, produce hundreds of thousands of tons of ore per day, which involves large footprints with considerable column height, and have a life of mine of over 20-40 years. These operations are typically located deep, under high stresses and in competent rock masses, making initiation and propagation of the caving process harder to manage. These challenges must be confronted by optimizing the fragmentation of the orebody to achieve smaller size blocks that will result in consistent caving and improved flow of the ore from the drawpoints. To achieve better performance from the drawpoints, preconditioning is applied to fragment and damage the material required to cave. We present a proposed design for preconditioning in underground mines, considering the challenges that these large-scale mines are already facing, based on a comprehensive analysis of current design parameters, case studies, and sensitivity analyses using numerical models.

Feb 2, 2021

By Batric Pesic

The interactions of mineral-pyrite with T. ferrooxidans were studied by using a cyclic voltametry technique. The interactions with bacteria were examined during the entire growth stage of bacteria (fermentation), The pyrite ?surface invariably drastically changed ' its. properties at the second day of fermentation. Beyond two .. days of fermentation, the cyclic voltamograms were insensitive to convective diffusion produced by stirring. The product layer was examined by SEM,. X-ray diffraction and chemical analysis. The SEM study revealed that bacteria populated the pyrite surface at an extremely high density levels. The high density of bacteria, and the solid reaction products formed on the pyrite surface created conditions for pore diffusion which explained why the CVs became .insensitive to convective diffusion in solution (stirring). The x-r:ay diffraction study confirmed jarosite as a product layer. A mechanism of T. ferrooxidans cells serving as nucleation sites for jiarosite formation is proposed.

Jan 1, 1991

By R. Pazhianur

Cathodic Protection using impressed current was employed to reduce the wear of the mill wall during ball mill grinding. Wear rates were determined from weight-loss measurements made on four, I-inch diameter, mild steel coupons installed flush with the interior surface of the mill wall. Grinding tests were conducted on quartz, pyrite and quartz-pyrite mixtures at pH values of 4.6, 7.1 and 9.2. Cathodic protection was shown to reduce mill wear by 40-60010. An examination of the coupon surfaces using scanning electron microscopy showed that cathodic protection greatly reduced pitting corrosion. The presence of a sulfide mineral, such as pyrite, was found to increase the wear rate significantly, possibly due to galvanic interactions. It is also found that the wear rate is significantly higher than the sum of abrasive wear and the corrosive wear, due to a synergistic effect.

Jan 1, 1996

By John D. Bardill

This report covers the magnetic surveying done in the Plattsburg area , which was part of a general survey, of magnetite deposits in New York State . Other areas being surveyed are the Star Lake district , St. Lawrence County ; Brewster district , Putnam County; and the Sterling district , Orange County. Reconnaissance indicated an area about 3 miles long and 1,200 feet wide , but detailed surveys have been completed on only a portion of that area . In several districts , surveys of this type have served as a basis in the selection of areas for exploration by diamond drilling by the Bureau of Mines .

Jan 1, 1947

By M S. Henderson, R D. Alorro, L G. Dyer

An alternative leaching system for rare earth element recovery from monazite is under development. The initial stage utilises oxalic acid to convert the rare earth phosphate into an oxalate salt through dissolution and reprecipitation and it is the efficiency of this stage that governs the overall recovery achieved. It has previously been proposed that lixiviant consumption is the primary limitation in this process. This work further investigates a range of conditions in an attempt to further elucidate the factors influencing the achievable conversion in this stage. It has been shown that the pH may be governed by multiple reactions both consuming and producing acid (thus the mild change over time). The importance of proper mixing and potential to operate at lower temperature with only moderate impact on kinetics has also been demonstrated. Staged/sequential leaching is more effective in fresh solution as opposed to restoring the lixiviant concentration with subsequent reagent addition, suggesting some impact of solution composition. However, contrary to previous findings, subjecting the leach residue to fresh solution resulted in significant decline in leach rate and overall dissolution. This may be because a greater proportion of conversion was achieved in stage 1 in this work than in previous investigation. This may indicate that eventual passivation or the presence of some more refractory REE minerals limits dissolution. Iron dissolution was relatively consistent upon exposure to fresh solution, displaying the ability of the solution to continue to leach the goethite component of the concentrate.

Aug 24, 2022

By L Klemettinen, A Jokilaakso, D Attah-Kyei, P Taskinen, M Tiljander, D Sukhomlinov, D Lindberg

In this study, the use of carbon neutral biochars as reducing agents in the pyrometallurgical treatment of nickel slag was investigated at 1400°C in order to recover valuable elements such as copper and nickel from the slag. A large amount of slag is generated during the nickel matte smelting. Nickel slag contains valuable elements such as copper, nickel and cobalt, which can be recovered. Disposal of this slag results in loss of resources and may cause pollution of the environment. It is important to retrieve these metals for environmental and economic reasons. In this study, the slag was reacted with non-fossil reducing agents (biochar) which were produced from hydrolysis lignin and black pellet biomass pyrolyzed at 600 and 1200°C and with metallurgical coke for comparison. The reduction experiments were done at 1400°C for 15, 30 and 60 mins under inert gas atmosphere. The samples were quickly quenched and analysed with Electron Probe X-ray Microanalysis (EPMA). The results showed that the use of biochar resulted in faster reaction kinetics in the reduction process compared to coke. The fast reaction kinetics is attributed to the relatively high content of volatiles in this biochar, leading to gas formation and thus mixing of the sample material. Moreover, thermodynamic modelling was also performed using FactSage™ to simulate equilibria with different amounts of biochar. The metal to slag distribution coefficient calculated from the results of thermodynamic modelling were consistent with experimental results. In addition, thermodynamic calculations confirmed that nickel is reduced rapidly and it deports to the metal alloy phase. As the reduction progresses or extra reductant is available for reactions, more iron is deported to the metal phase. The calculations also revealed that Zn vaporises into the gas phase.

Jun 19, 2024

By K Verbeken, D Seveno, A Maslov, I Bellemans

Recycling and decarbonisation current metallurgical processes is key for our planet’s future and in both cases, digital twinning will play an important role. However, the various modelling techniques being used for digital twinning require a lot of input values on variables such as viscosities, diffusion coefficients and surface energies that need to be known as a function of temperature, atmosphere and composition, but which are not widely available, such as in databases, for molten slag phases. The need for more accurate data on physical slag properties is clear and will be extremely relevant for making more realistic and quantitative simulations. Some of these properties are difficult to determine, which is inherent to the very high pyrometallurgical temperatures. Therefore, this work focuses on some aspects related to determining electrical conductivities, viscosities and surface tensions of slags via a combined experimental-modelling method. Besides experimental work, molecular dynamics (MD) simulations can be used to investigate oxidic slag physical properties. With MD simulations, one can follow the time evolution of a system (consisting of atoms or molecules) by integrating Newton’s equation of motion. The input for an MD simulation mainly consists of a force field as well as initial positions, velocities and mass of each atom. The determination of the transport properties in existing literature of MD simulations in oxidic systems, is typically based on incorrect assumptions. For example, to determine the ionic conductivity, the frequently-used Einstein-Stokes equation fails to take into account all ionic types and neglects correlated motion. Furthermore, the viscosity determination via the Einstein-Stokes formula also assumes independent motion of the different ions. This paper gives a brief overview of the opportunities and challenges related to the use of MD simulations for oxidic slag systems.

Jun 19, 2024