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By Luis Fernandez-Deza, James Hawn, Dustin Mount, Jean-Marc Wehrli

The RiverRenew Tunnel System project in Alexandria, VA forms part of a CSO scheme aimed at reducing overflows of combined stormwater and sewage into the Potomac River during storm events. A major piece of the project is a 12-foot internal diameter tunnel of approximately 12,000 feet length lined with a single-pass precast concrete segmental liner and excavated by an Earth-Pressure Balanced Shield TBM. The tunnel lies between 120 to 140 feet below grade in the clays of the Upper Potomac Formation with occasional dips of more granular, saturated soils of the Terrace Formation and the Alluvium. The TBM is launched from a figure-8 configuration Pumping/Screening Shaft located within AlexRenew’s operational Water Resource Recovery Facility. This paper discusses the challenges encountered during the launch of the TBM in short mode within a highly congested site and from narrow deep shafts.

Jun 13, 2023

By Marcos Vieira, Gil Vilela, Wanderson Silvério, Livia Faustino, Pierre Fernandes

New global industry standards and regulatory changes regarding mining tailings management are driving installation of tailings filtration plants to decommission existing tailings dams and implement dry stacking. Target of this project was to reduce ultrafine slime tailings deposition. Previous investigation at Samarco concentrator has showed a 35% decrease in tailings filtration throughput when feeding a mix of 95% flotation tailings with 5% slime tailings (compared with 100% flotation tailings), also worsening geotechnical aspects such as material workability during dry staking. Industrial trials using a proper filter aid at tailings filtration plant feeding a mix of 94% flotation tailing and 6% slime tailing (equivalent to 30% of total slime generation) have provided filtration performance maintenance (throughput and cake moisture), and dry stacking the dewatered material. Results achieved will enable life expansion of existing slime disposal structures, as well as potential life of mining extension. Furthermore, reagent chemistry influence is discussed by the light of geotechnical aspects, which has been showing improved KPIs, such as workability, compressibility and permeability.

Feb 1, 2025

By C. G. Anderson

In some parts of the world, silver chloride occurs naturally in deposits of cerargyrite (1) (i.e. horn silver). In other cases, silver chloride is produced and exploited for its well- known photographic or electrochemical properties. In this case, it is a valuable commodity needing no further refinement. However, silver chloride is frequently encountered in precious metals refining. In most cases, it is a by-product that occurs in small amounts. For example, it is a common occurrence in gold refining when using the Miller and Wohlwill refining processes or when parting fire assay beads. As such, the mode of reduction to elemental silver is of little impact on the overall refining economics. Thus, a variety of reduction methods are employed all enjoying varying degrees of popularity (2). On the other hand, silver chloride serves as a key intermediate in the production of fine silver by nitrogen species catalyzed acid pressure leaching of refractory silver concentrates. This has most recently been practiced at the Sunshine Mining & Refining plant located in Kellogg, Idaho. Thus, efficient methods of reduction, precipitation and materials handling on an industrial scale are of the utmost importance. In this presentation, the evolution of these methods will be detailed.

Jan 1, 1997

By Werner Wenzel

Methods to increase the gas penetration through sinter layers. In the field of agglomeration, sintering has gained importance, specially in Europe; in Best-Europe this trend will continue till the year 1980, since it is quite probable that in the blast furnace burdens with 50-60 sinter, 10-20 % pellets and 20-25 % ore lumps will be employed. In order to meet this demand for sinter, new sinter bands with reaction areas between 300-400 m2 will be constructed. Chemical and physical phenomena during the Suction-Draught-sinter process. Iron ore sintering is generally considered as a burning process where the material contains 90-95 % ash i.e. non-combustible ingredients. Sintering represents a heterogeneous exothermic reaction in which the chemical phenomena as combustion, calcination, hydration, reduction and oxydation are superposed by physical phenomena. The physical phenomena are devided into material transport and simultaniously occurring heat transport processes. The velocity of these combined physico-chemical reactions i.e. the change in the reaction site per unit time determine the efficiency of the sinter process. The gas permeability as an important criterion of heat transport during the Suction-Draught sinter process.

Jan 1, 1971

By C. N. Logan

The Southern Company is one of the nation's largest electric utilities and is the parent firm of five operating companies: Alabama Power, Georgia Power, Gulf Power, Mississippi Power and Savannah Electric and Power. Another subsidiary is Southern Company Services (SCS) which provides engineering and technical sup-port to the five operating companies. This technical support includes the procurement and supply of over 40.9 Mt (45 million st) of coal annually for the 22 coal fired plants in the system. Approximately 80 percent of this tonnage is purchased under long term contracts and the remaining 20 percent is purchased on the spot market. The coal is principally supplied from Alabama, Illinois Basin and the eastern Appalachian coal fields. Most of the coal is delivered by unit train and barge but one plant in Alabama receives all its coal by truck and conveyor belt.

Jan 1, 1990

By M. C. Fuerstenau

A number of interesting and. important phenomena were revealed during a study of the response of beryl to sulfonate flotation (1). Perhaps the most important observation is the effect of various cations on flotation response. Experiments showed that in the vicinity of pH = 3. 0, about three ppm Fe.+++ increased recovery of leached beryl from about 60 to 100 per cent, whereas about four ppm Ca++ reduced the recovery from 60 to 2 per cent. With the exception of ferric iron, all of the other cations investigated reduced flotation recoveries drastically at this pH. As postulated in the paper "Sulfonate Flotation of Beryl", (1) even with low concentrations of polyvalent cations and sulfonate (on the order of one ppm), cation¬ sulfonates are precipitated immediately in solution. That is, blueish-white clouds .were noted to form after given additions of salts to. known solutions of sulfonate. Furthermore, it was also shown that one-hundred-fold more ferric iron than necessary to form the precipitated cloud had to be added to effect complete flotation. In other words, some form of solid ferric sulfonate was found to function as the collector in these systems. The form of the compound was suggested to be Fe (RSC3)2OH and that bonding to the surface occurs through the hydrogen of the hydroxyl. As the form of this compound was shown to be dependent on the extent of hydrolysis of ferric iron, it is to be expected that ferric iron will be unique in some pH region. Further, if the presence of hydroxyl in the neutral precipitated compound is of primary importance, then other cations should function similarly but at different values of pH, since they will hydrolyze at different concentrations of hydroxyl ion. To determine whether the premise of hydrolysis is correct, the study was extended to quartz systems lit the presence of various cations at various values of pH.

Jan 1, 1964

By Hans von Michaelis

It is difficult to fail if one has a great deposit, but 'great' ore deposits are few and far between. More often one hears that a mine has been 'made' rather than found. This is particularly true for industrial minerals and for gold and silver projects. Even the best ore deposit can often be improved through innovative technology, e.g. the Escondida copper mine in Chile, where a novel ammonia leaching process is yielding a fabulous DCFROI. Consider the case of a small high grade gold mine. Previous owners had found inadequate reserves to justify the capital cost of developing the mine and installing a mill. Lower grade resources had been ignored because the owners were looking only for grades that would be high enough to support a small underground mine and mill. Randol, assisted by Kappes Cassiday & Associates, determined that the ore was amenable for heap leaching. Secondly, existing drillhole data indicated a significant lower grade resource that appears to be accessible to open pit mining methods. In this case, the appropriate selection of off-the­shelf technologies has literally 'made' the mine. At the Randol at Vancouver '94 conference on Latin American Mining Opportunities, papers on innovative technolo­gies for exploration, mining, metallurgy and environmental management were presented in non-technical terms for managers and resource developers. It was surprising how few of the exploration- and finance-oriented delegates participated in these sessions. Numerous technologies were presented that could be added to one's arsenal of tricks to 'make' a mine, i.e. to convert resources into ore reserves through knowledge.

Jan 1, 1995

By Raúl Castro, Marco Vera, Alfonso Ovalle

The underground mining evolution for block cave mines in Chile and worldwide has made important strides in the last decades. Nonetheless, reserves determination in the initial stages of these types of projects—mainly for long-term planning—is not studied in as much detail as it should be, especially regarding the impact on the final value of the enterprise. Today, the first estimation of the size of a block cave mine, typically expressed in tons, tends to determine very large footprints and ore bodies. The resulting large-scale mine is obtained by applying the marginal cut-off grade (COG) to determine reserves. Yet, in many cases, it is possible to obtain an equal or higher benefit, extracting fewer reserves in less time, with a smaller active area, which significantly reduces the project’s uncertainty. To explore scenarios obtained by applying a higher marginal COG in the initial phases of the project, the Hill of Value methodology is used to estimate the net present value (NPV) in relation to the production rate and the COG. However, the application of this methodology considers certain simplifications that generate results which are not completely satisfactory in specific cases. This paper suggests an improvement of this method to obtain more reliable results regarding determination of a COG profile that will optimize the NPVof a block-cave project. The methodology was developed and applied in a massive polymetallic deposit with zinc, lead, and silver mineralization, corresponding to a real block caving project. The methodology provides NPV results that differ by approximately 15% in comparison to the real mine plan, while also being considerably simpler and faster to calculate. In summary, the proposed methodology provides a reasonable and fast procedure to estimate higher than marginal COG that increases the NPV of block cave mine projects.

By J. H. Kelley

In this paper, we show that the methane emission and the dust generation in under-ground mining currently and in the future pose operational, health and safety conditions which adversely Impact face productivity and worker satisfaction. One solution is the use of a dual-aircourse system of ventilation. In this concept, one aircourse captures and exhausts to the surface the dust generated and the methane emitted in coal/mineral fragmentation while a second aircourse provides workers with cleaner air for breathing and comfort. Various dual-aircourse configurations adapted to the Variable Wall Miner are analyzed and compared with conventional mining in gassy seams, indicating a marked reduction in the required air quantity and the number of aircourses.

Jan 1, 1996

By B. P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using carbonate solutions. The objective of the present study was to increase the absorption rate of CO2 into the carbonate solution without reducing the absorption capacity of the solution. This approach used a polypropylene glycol methyl ether (PPGME) as a surfactant to chemically alter the gas bubble size. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations of 0, 0.12, 0.24, 0.36 and 0.48 g/L. Results showed that as the concentration of surfactant increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 mmol/min CO2 at 0 g/L PPGME to 3.92 mmol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in absorption capacity of the solution.

By K. D. Luxbacher, E. C. Jong

Perfluoromethylcyclohexane (PMCH), a member of the perfluorocarbon tracer group of compounds, has been shown to be a viable supplement to the widely used tracer gas sulfur hexafluoride (SF6). This viability stems from the fact that PMCH can be used concurrently with SF6 while maintaining adequate chromatographic separation and comparable sensitivity during analysis. However, the release of PMCH in an underground mine ventilation system is challenging due to its physical characteristics. While SF6 exists as a gas at room temperature and pressure and can be accurately released by a variety of means, PMCH exists as a volatile liquid at room temperature and pressure, preventing it from being deployed in a similar manner. One method to release PMCH is to use a permeation plug passive release vessel (PPRV), which allows for the controlled release of the gas. This paper presents the results of a study evaluating various preparation techniques, plug thicknesses and plug materials of an aluminumvessel PMCH release source, so that a source appropriate for the mine scale may be developed.

Jan 1, 2015

By J. Franko, M. S. Klima

Wet-drum magnetic separators are used extensively for upgrading iron ore and for magnetite recovery in dense-medium separation circuits. In this study, the performance of a continuous, laboratory wet-drum magnetic separator was evaluated both with and without the application of ultrasonic energy when processing dense medium slurries. Test variables included magnetic-to-nonmagnetic ratio, solids concentration and nonmagnetic material. The results indicate that, under certain conditions, the purity of the magnetic material increased after ultrasonic treatment. Key words: Ultrasonics, Wet-drum magnetic separation, Iron ore

Jan 1, 2003

By Mehmet Ali Recai Önal, MAHMUT CAMALAN

Mineral liberation is one of the primary objectives in comminution circuits for the downstream separation of valuable minerals. Breaking minerals through their grain boundaries (grain-boundary breakage) enables mineral liberation in their natural grain size, removing the need for intensive grinding. This study aimed to evaluate if gaseous carbon dioxide, oxygen, or hydrogen can be used as grinding additives to promote the liberation of chromite grains by grain-boundary breakage. For this purpose, chromite ore particles in the −9.53 + 6.35 mm size fraction were pretreated by exposing them to carbon dioxide, oxygen, or hydrogen flow. Then, the untreated and pretreated samples were broken in a drop-weight tester under the same conditions. Finally, the graderecovery plots of chromite grains in the selected progeny size fractions and the overall progeny distributions were measured and compared. Pretreatment with carbon dioxide flow was found beneficial for grain-boundary breakage. It significantly enhanced the liberation of coarse chromite grains along with the overall progeny fineness. EPMAanalysis showed that the adsorption of carbon dioxide seems to reduce aluminum concentration at grain boundaries, which could be the reason for grain-boundary weakening. These results suggest that carbon dioxide can be used as a grinding additive, reducing the carbon footprint of the mining industry.

Oct 29, 2020

By John D. Price

In the constant search for ways and means of improving the quality of coke and thus making its use at the blast-fornace more satisfactory and economical, it has become increasingly evident that the present laboratory tests do not show the full picture of a coke's value as a blast-furnace fuel. This fact was recognized by Dr. A. C. Pieldner thirty-five years ago: (Ref. 1) here is perhaps no phase of fuel technicology which has aroused more discussion or regarding which there is more difference of opinion than the properties of coke which make it most suitable for blast-furnaces and other uses." Dr. Fieldner followed this assertion with a statement to the effect that men who write on this subject today (1923) have, because of conflicting experimental evidence brought forth in recent years, far less positive opinions on the matter than did writers of some years past. One is led to wonder if these statements are not just as true now as they were when first made.

Jan 1, 1959

By CHENCHEN SUN, GUOPING LUO, GUOCHENG ZHANG

Preparation of briquettes by adding CaF2 reagent into the Australian iron ore powder. The structure and morphology of iron ore briquettes during various reduction stages (i.e., Fe2O3→Fe3O4, Fe3O4→FeO, and FeO→Fe) were observed via an ore microscope and scanning electron microscopy. The results showed that CaF2 reacted with SiO2 to form CaO and SiF4 gas during the roasting process. The reduction swelling index decreased from 12.36 to 8.83% when the CaF2 content in the briquettes increased due to CaF2-mediated refinement of the hematite grains during the first stage of the reduction process. Lattice distortion resulting from the presence of Ca2+ in the FeO lattice during the second stage of the reduction process, coupled with an increase in the porosity of the iron ore briquettes and the formation of a low-melting-point slag phase, promoted the anisotropic growth of FeO lamellar crystals, which resulted in an increase in the reduction swelling index from 4.27 to 7.36%. During the third stage of the reduction process, the growth of iron whiskers was promoted by wüstite (FeO) lattice distortion caused by a solid solution of Ca2+ in the FeO lattice; the reduction swelling index increased from 15.61 to 24.72%, resulting in the catastrophic swelling of the iron ore briquettes.

May 27, 2021

By Robert Rennie, Taylor Davies, Ahsanul Rafi

Electric locomotives powered by extensive electrical cabling systems were prevalent in the mining industry in the early days of the 20th Century [1]. Since the movement of tethered electrical mining locomotives was limited, the advent of diesel-powered mobile mining equipment provided more flexibility. This led the mining industry to be dominated by diesel-powered locomotives for most of the 20th Century and the entire 21st Century, to date. However, diesel power has certain drawbacks. Diesel-powered vehicles produce tailpipe emissions such as diesel particulate matter, carbon dioxide, sulfur dioxide, and nitrogen oxide. Mine workers exposed to these emissions were, and continue to be, subject to health issues such as respiratory problems, increased risk of lung cancer, and cardiovascular disease. [2][3]. Extensive ventilation systems are required to dilute the diesel exhaust and dissipate the heat generated by these vehicles. Moreover, as mines are getting deeper due to depleting resources, ventilation costs in diesel-powered mines are becoming increasingly high. These factors, coupled with the trend towards greenhouse gas (GHG) reduction in mine operations, has allowed zero-emission electric locomotive systems to gain traction. As lithium-ion battery technology is becoming more advanced, battery-powered electric vehicles can now perform duty cycles comparable to those of diesel-powered vehicles. Although battery-electric vehicles (BEVs) are comparable to diesel-powered vehicles in terms of mobility, they have certain limitations. For instance, the amount of onboard energy is limited by the battery energy density and specific energy. The MT42 diesel haul truck from Epiroc, for example, has a fuel tank capacity of 580L, which is equivalent to around 1450 kWh of net electrical energy [4]. The electrified version of the MT42, on the other hand, has an onboard battery with 375 kWh of usable energy weighing around 4.9 metric tonnes [5]. Moreover, storing and refueling of diesel-powered vehicles is simple and quick, whereas battery energy storage and charging systems require extensive infrastructure development. Charging time is mostly limited by battery chemistry and design. Due to these limitations, the benefits of battery-powered mining vehicles are more likely to be realized with proper planning and optimization of the BEV fleet. This includes optimizing mining layouts for BEV use, charging infrastructure design, and management of onboard energy storage systems.

Jun 25, 2023

By Jung-Joo Kim, Jong-Uk Kim, Turab H. Jafri, Han-Kyu Yoo

"INTRODUCTION Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. In practice, while designing the tunnels with the help of numerical analysis, steel sets are generally considered only as temporary support elements. Only a few studies propose the direct application of composite support in the tunnel design, based on large-scale experiments and numerical analysis. In order to assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the experimental results, numerical analysis was performed to assess the application of composite support in tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed in the light of different structural patterns. LARGE-SCALE EXPERIMENTS USING COMPOSITE SUPPORT Preparation and Procedure of the Experiments The preparation setup as well as the organized procedure of the large-scale experiments using composite support is shown in Figure 1. An appropriate geometry of the specimens was selected by considering the standard cross-section of a two-lane highway tunnel in South Korea. Under the loading conditions meant to develop the axial forces and bending moments simultaneously, arch-shaped specimens were assembled with the ends of the specimens subtending a 60° arc angle at the center of the arc circle as shown in Figure 2. The fabrication of six specimens was completed in two groups based on the dimensions of steel sets, with the first group of three specimens being reinforced by H100 (No.1, No.2, No.3) and the other three by H125 (No.4, No.5, No.6). In order to reduce the voids on the boundary of the shotcrete and steel sets, concrete was casted over the steel sets instead of using shotcrete. The specimens were designed to incorporate the uniaxial compressive strength of 21 MPa. Shear keys and steel plates were installed at the ends of the specimens, so that shear failure could be avoided at the ends and the specimens could also be protected from detachment at the fixation. Translational and rotational movements at the ends of specimens were fixed."

Jan 1, 2016

By Emily Wortman-Wunder

As the 2011 president of the Society for Mining, Metallurgy, and Exploration, Inc., I am pleased to present the 2011 issue of the Transactions of the Society for Mining, Metallurgy, and Exploration, Vol. 330. A significant portion of the contribution that we as a professional society make is the publication of professional and technical papers that accelerate the advancement of scientific knowledge and enable the transfer of technology. Communication within the mining community is the key to a successful society. This technology exchange continues a tradition that dates back to the 1871 meeting of 22 mining engineers in Wilkes-Barre, PA, that resulted in the founding of AIME; those individuals envisioned that these transaction volumes “would form a most valuable and greatly needed addition to our professional literature.” This volume fulfills that pledge. The 2011 Transactions is the second Transactions to take advantage of new publication technologies. It appears solely in electronic format. The decision to go to an all-digital format for this longstanding publication was a difficult one, but one which will better serve the mining community. Based on the feedback from the 2010 Transactions in e-book format, I believe that the transition to the all-digital format was the proper decision. The 2011 Transactions contain some of the most interesting research from the past year, including a 10-year profile of roof and rib fall trends from the National Institute of Occupational Safety and Health (NIOSH) and a new cross-disciplinary application of the tools of epidemiology to assess and mitigate risk in coal mines . This 2011 Transactions comprise of a total of 82 technical papers (626 pages including index), including all 19 papers published in 2011 in the Technical Papers Section of Mining Engineering magazine (Vol. 63) and all 32 papers published in 2011 in Minerals & Metallurgical Processing (Vol. 28). Additionally, this volume contains 31 papers that are being published for the first time in this issue. The papers presented in this volume were written by some of the most distinguished professionals in the industry worldwide. All 82 technical papers were peer-reviewed. The process of review and publication requires much hard work by authors, reviewers and our publications staff. As the 2011 president of SME and on behalf of all our members, I would like to extend our gratitude to all whose volunteer efforts contributed to the publication of this volume.

Jan 1, 2011

By Arcy R., D&apos George

Removal of S02 from smelter gases is being investigated, using an innovative technique that results in the almost simultaneous recovery and production of elemental sulfur. S02 is removed from the gas stream by scrubbing with suitable aqueous salt solutions or high-boiling organic fluids. The S02-laden liquor is then reacted with H2S Crystalline, high-purity sulfur is instantly precipitated and, after filtration, the regenerated liquor is recycled. The H2S required for the process is produced by reacting a portion of the recovered sulfur with hydrogen or with methane and steam. The chemistry and results of preliminary laboratory research are discussed.

Jan 1, 1969

By Harrison R. Cooper

Approximately 40 concentrators throughout the world have successfully adopted computer control for flotation circuit operation since 1969. Successful use of flotation control, gaining up to 2% efficiencies, has largely derived from effective employment of on-stream slurry analyzers and integration of key measurement data through digital processors. Requirements for reliable measurement have also led to improved functional reliability in magnetic flow meters, pH, reagent feed, and other key elements. Methods used in computer control of flotation will be reviewed and variations in operating philosophies will be described with reference to the approaches taken to flotation automation.

Jan 1, 1979