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The viability of physico-chemical purification methods such as selective flocculation for separation of two components having similar chemical composition and same crystal structure but different surface properties is demonstrated. Loss of selectivity was observed in a dolomite-dolomite mixture with Polyethylene Oxide (5 million molecular weight) as the flocculant. Hetero-flocculation was minimized using a low molecular weight PEO (MW -105) as the site blocking agent (SBA). Near complete separation was achieved at pH 10.5 at 100% recovery level.

Jan 1, 1993

By Boris CARO VARGAS, Bernard Theron

"In early 2014, Nicholson Construction Company was awarded, together with its tunneling sister company Bessac, the Norris Cut Miami Tunnel Project. The 2.5-meters diameter segmental lined tunnel, 1600-meters long, is aimed to replace the existing 54” force main connecting the Waste Water Treatment Plant (WTP) on Virginia Key to Fisher Island. To overcome project challenges such as the highly permeable limestone of the Fort Thomson Karstic Formation (one of the most permeable formation in the World), the project team has developed State of the Art solutions: The TBM was launched with pipe-jacking technique for the first 70-meters and then converted to segment erection mode. It allows substantial schedule savings and drastically reduces the size of the circular launching shaft. The TBM, jointly designed and manufactured by Bessac and Herrenknecht, can convert from slurry to EPB mode within a few minutes. The cutters can be replaced by wet divers thanks to an innovative application in the TBM industry. PRESENTATION OF THE PROJECT The aim of this project is to replace the existing 54-inch force main pipeline which transmitted all sewage collected from Miami Beach, Surfside, Bal Harbour, Bay Harbor, North Bay Village and Fisher Island to the Central District Wastewater Treatment Plant (CDWWTP) to Fisher Island. The existing pipeline consisted of pre-stressed concrete cylinder pipe which is in poor condition in a number of locations and could be subject to sudden failure. An adjacent portion of this existing force main under the Government Cut (North Fisher Island) has already been replaced as part of a previous design-build contract and involved the installation of a 60-inch diameter fiberglass-reinforced mortar pipe installed inside a micro-tunneled casing."

Jan 1, 2016

By B. A. Slaker, T. Miller

"An underground limestone mine in eastern Ohio was experiencing significant floor heave and roof falls, attributed to high horizontal stresses. Areas of the mine showing floor heave were monitored with roof-to-floor extensometers and photogrammetry surveys, to determine the rate and magnitude of heave. Extensometer data were recorded hourly at four locations across adjacent entries while photogrammetry surveys of the floor were performed at the same locations every two to five weeks. A final survey was performed using an I-Site 8200 laser scanner. Following instrumentation, floor heave up to 10.1 cm (4 in) was measured by the extensometers, photogrammetric reconstructions, and laser scanner over a 6-month period. The extensometers were biased by the location where they were placed, failing to consistently capture the location and extent of floor heave and cracking. The photogrammetry surveys were not precise enough to capture small magnitude movements. Mining in the area was halted and within several months the floor movement and incidence of roof falls was significantly lessened. INTRODUCTION Limestone formations in the United States can be subject to relatively high horizontal stresses due to the presence of tectonic loading of the strata. Horizontal stresses have a documented history of causing stability issues in underground limestone mines. Kuhnhein and Ramer (2004) discussed the influence of horizontal stress on complex ground control interactions associated with limestone pillar design and mine layouts. Esterhuizen et al. (2008) documented roof damage observations associated with high horizontal stresses such has roof guttering, beam instability, oval-shaped falls, and failure propagations. There have also been a number of documented case histories of horizontal stress causing unexpected roof and pillar failures at shallow depths (Stacey and Yathavan, 2003). To the knowledge of the authors, there has only been one well-documented case of floor failure causing stability issues in an underground limestone mine. Murphy et al. (2015) documented the role that a weak, moisture-sensitive floor had in the development of a massive roof collapse. For this paper, the study site neighbored, and was in the same general geology of, the site in Murphy et al. (2015). However, the weak, moisture-sensitive floor was not present for the current study. The current study site has experienced significant floor instabilities caused by high horizontal stresses. The instability area was monitored using two different methods to determine if the floor failure would eventually propagate into roof or pillar failure. The objective of this paper is to analyze displacement monitoring measurements from string potentiometers and remote sensing techniques in an area experiencing active movement. Based on the measurement trends and observed damage from inside of the mine, the presumed failure process will be discussed."

Jan 1, 2017

By L. G. Austin

Introduction My first contact with industrial milling was during the time I worked in the electricity generating industry in the United Kingdom. In visits to power stations to investigate either deposits in the boiler furnaces or polluting deposits settling around the stacks. I had to check the performance of the vertical coal pulverizers, since poor pulverization aggravated both problems. Naturally, then, when I came to the USA in 1957 to take a PhD in fuel technology at Penn State, I was put to work to review the science of coal pulverization. After this reviewing, I was completely confused. On one hand, there was a well-developed understanding of stress-strain equations, and a rap- idly developing knowledge of how stressed, brittle solids fractured, based on the Griffith crack theory. On the other hand, reading in the grinding literature gave me: • Kick's Law, which was clearly not correct in the light of modern fracture theory; • Rittinger's Law, which was also clearly not correct; • Bond's Third Law of Comminution, which was claimed to have something to do with the Griffith crack theory, but where the connection between the two was made by intuitive pseudo- scientific reasoning I could not accept; • the choice of mill motor power for the most common type of coal mill, the Raymond pulverizer, was calculated from the fan power required to move air through the mill. Although I could accept the empirical connection between the two, it made no sense from the point of view of fracture energy. Even today, most books or review chapters on size reduction start from these laws. incorrect statements abound in the literature, such as “the Hardgrove Index is based on Rittinger's Law," which it is not, "The Bond theory states that work input is proportional to new crack tip length produced in particle breakage," which is not true, etc. My own test work showed that these "laws" did not fit the data for grinding of coal. At about this time, Epstein (1 948) and Broadbent and Callcott (1 956), following the original work by R.L. Brown (1941) at the British Coal Utilization Research Association, proposed describing breakage as a series of fracture stages. I took their concepts and developed the basic differential equation for a batch grinding process continuous in time, analogous to a batch chemical reactor. Robin Gardner then joined the project and did his PhD on treating batch grinding in the same way as a batch chemical reactor. He found that the basic equation had already been partially derived by Sedlatschek and Bass (1 953) in Germany. We confirmed experimentally the validity of the equations for describing batch grinding (1 962) and formulated the equation describing steady-state continuous grinding in a fully-mixed mill. At about the time this work was published, Gaudin and Meloy (1962) and Filippov (1961) independently published essentially the same equations, but without experimental proof of the validity of the concepts. I will give a brief overview of what these beginnings had led to in the design of mills for size and power, and show some of the results of this more detailed understanding of grinding processes. Concepts of Fracture Mills such as tumbling ball, rod, pebble and autogenous mills and vertical mills such as the Raymond, and E-type apply compressive stress to lumps or particles relatively slowly. Compressive stress applied to a particle of an elastic brittle solid imparts overall strain energy to the solid and produces local regions of tensile stress, (Fig. 1) (Berenbaum and Brodie, 1959). Irwin (1949) showed from solution of the stress-strain solutions that a small hole in a region of tensile stress reduces stress concentration at the hole, that is, the tensile stress at the tip of a crack or flaw in a solid is much higher than the general tensile stress in the region. The longer the crack, the higher the stress concentration. Griffith (1920) hypothesized that when the regional tensile stress is large enough, then the chemical bonds at a preexisting crack tip are stretched to breaking point, as illustrated in Fig. 2. When the bonds break, the crack becomes longer, the tensile stress concentration increases, the situation is unstable and a crack opens up (propagates) a surface of tensile stress, creating its own tensile stress at the leading edge. Stored strain energy is converted to the kinetic energy of the moving stress field, which is analogous to sound propagation through the solid, so the crack tip accelerates to velocities approaching those of sound. The moving crack will pass through regions that were previously under regional compressive stress. The equations for "ideal" and "Griffith" strengths are where a is the intermolecular distance, y is Young's modulus, g is the energy

Jan 1, 1998

By Bryan Ulrich

Knight Piésold?s annual roundtable discussion was held at the Red Lion Hotel and Casino in Elko, NV on March 14. This year the title was, ?Roundtable discussion on material co-disposal/ co-placement in the mining industry.? This topic was chosen because of the benefits that the mining industry could realize through the advancement of improved methods of storing tailings and mine waste and from reducing short-and long-term environmental hazards while reducing the footprint of these facilities and making strides toward attaining a walk-away solution. Knight Piésold had a local representative, Bryan Ulrich, as well as representatives from its Denver, CO office, including Tom Kerr, president of Knight Piésold?s U.S. practice, and Jeff Coffin, Ph.D., geotechnical engineer, to help facilitate the discussion. The event played host to about two dozen attendees from several western states. Attendees included personnel from more than 10 mining properties, various corporate offices and academia. The purpose of the roundtable was to exchange ideas and information pertaining to broad topics revolving around the subject of co-disposal/co-placement in the mining industry. Compared with traditional conferences and symposia, the roundtable forum tends to provide a less inhibited format for discussion. In the roundtable format, lively discussions and applicable tangential departures are encouraged. This was the seventh in the series of the Elko Roundtable events. Previous roundtables pertained to: ? Heap leach pad design, construction and operation. ? Design, construction and operation of tailings storage facilities. ? Site-wide water considerations. ? Mine closure and cover design. ? Strides toward sustainability in mining. ? High-density tailings, paste and filtered tailings. Acid rock drainage for engineers and environmental scientists.

Nov 1, 2013

By Nik Sokol, Eric Sekulski, Leo Weiman-Benitez, Jon Hurt, Shrinidhi Vijayakumar, Phaidra Campbell

The Silicon Valley Clean Water (SVCW) Gravity Pipeline (GP) is the first Progressive Design Build (PDB) tunnel completed in North America. As part of the Regional Environmental Sewer Conveyance Upgrade (RESCU) Program, the tunnel is a key component to replacing and rehabilitating components of the existing conveyance system in San Mateo County, California. The GP consists of a large diameter Fiberglass Reinforced Polymer Mortar (FRPM) pipe installed inside a 4.1 m (13.5 ft) inside diameter, 5.3 km (3.3 mile) long precast concrete segmentally lined tunnel. The tunnel was constructed using a 4.6 m (15.2 ft) diameter Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) through heterogenous silts, clays and sands. Construction included two separate TBMlaunches from a centrally located access shaft, and a tunnel alignment below but in close proximity to very soft Young Bay Mud. Settlement criteria and mitigation strategies focused on protection of an existing 1.42 m (56 inch) diameter force main and adjoining structures along the alignment. This paper discusses the results of the theoretical settlement analysis versus the actual observed ground movements, while also presenting mitigation measures and adjustments made during tunneling to reduce the risks of adverse settlement.

Jun 13, 2023

A case study of a systematic approach to grinding circuit steady-state optimization is presented. After overall review of the flowsheet, two circuits were prepared for detailed testing. Functional performance analysis was chosen as the primary modelling system, and on this basis a quality assurance program for data gathering was implemented. A number of circuit design and operating variables were experimented with statistical analysis of plant test results revealed relationships previously unquantifiable by any other modelling technique. Improvements in classification system and mill grinding efficiencies were demonstrated and significant energy cost savings thus realized.

Jan 1, 1998

By M. Raffaldi, J. Johnson, M. Stepan, D. Benton

"The Office of Mine Safety and Health Research (OMSHR), Spokane Mining Research Division (SMRD), is continuing its High-Energy High-Displacement (HEHD) testing of field-scale shotcrete panels. A test program was developed to determine the relationship between applied force, displacement, and energy for both unreinforced and reinforced shotcrete panels. Reinforcement options consisted of synthetic macro-fibers, sprayed polyurea liners, chain-link fence, welded-wire mesh, and combinations of these products. During testing, photogrammetry was used to measure the geometric changes of the panels, including volume changes and panel cracking. These measurements were correlated with the load and displacement data, allowing visual observation to be related to the applied force and displacement. The test results provide a comparison of the mechanical performance of the various panel types and can be used by the practicing engineer to evaluate installed support based on visual observation of cracking and deformation. Visual assessment of the loading cycle and strength capacity of shotcrete in underground excavations will improve mine safety by providing a means to quantify the stability of installed shotcrete support. INTRODUCTION The National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health Research (OMSHR), Spokane Mining Research Division (SMRD) is continuing research on the behavior of shotcrete when used as the surface support component in mining ground support systems. Ground control safety often depends on supporting, or at least containing, the ground between the rockbolts. Shotcrete and mesh, in various combinations and with other components, are often used to accomplish this (see Figure 1). Maintaining support pressure during ground deformation is key to the performance of these systems, and to ensuring miner safety. However, the toughness of a ground support system–the ability to maintain strength over large deformations–is difficult to quantify. Researchers at SMRD have responded to this deficiency by designing a full-scale test device, described previously by Martin et al. [2015a], and beginning a testing program to assess the behavior of shotcrete surface support reinforced with a variety of products including: fibers, chain-link mesh, welded-wire mesh, spray-on polyurea liners, and combinations of these products. This paper presents the findings of these tests."

Jan 1, 2016

By R. W. Bartlett

I first met Milton Wadsworth in 1951 as an eighteen year old junior taking his mineral processing course at the University of Utah. He guided my senior thesis, evaluating the then new polymer flocculants on settling uranium leached ore pulps. This was before ion exchange and solvent extraction. After my military service and a brief working stint at Kennecott he supervised my PhD work. He encouraged me to be active in AIME and its constituent societies, where both of us have been directors of AIME and presidents of TMS. He has been a consultant for research groups that I have managed. Above all, he has been my mentor and friend for nearly 45 years. Thus, I am honored and particularly pleased to receive 5MB's Wadsworth Award.

Jan 1, 1996

By M. Raffaldi, J. Johnson, M. Stepan, D. Benton

"The Office of Mine Safety and Health Research (OMSHR), Spokane Mining Research Division (SMRD), is continuing its High-Energy High-Displacement (HEHD) testing of field-scale shotcrete panels. A test program was developed to determine the relationship between applied force, displacement, and energy for both unreinforced and reinforced shotcrete panels. Reinforcement options consisted of synthetic macro-fibers, sprayed polyurea liners, chain-link fence, welded-wire mesh, and combinations of these products. During testing, photogrammetry was used to measure the geometric changes of the panels, including volume changes and panel cracking. These measurements were correlated with the load and displacement data, allowing visual observation to be related to the applied force and displacement. The test results provide a comparison of the mechanical performance of the various panel types and can be used by the practicing engineer to evaluate installed support based on visual observation of cracking and deformation. Visual assessment of the loading cycle and strength capacity of shotcrete in underground excavations will improve mine safety by providing a means to quantify the stability of installed shotcrete support. INTRODUCTION The National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health Research (OMSHR), Spokane Mining Research Division (SMRD) is continuing research on the behavior of shotcrete when used as the surface support component in mining ground support systems. Ground control safety often depends on supporting, or at least containing, the ground between the rockbolts. Shotcrete and mesh, in various combinations and with other components, are often used to accomplish this (Figure 1). Maintaining support pressure during ground deformation is key to the performance of these systems, and to ensuring miner safety. However, the toughness of a ground support system–the ability to maintain strength over large deformations–is difficult to quantify. Researchers at SMRD have responded to this deficiency by designing a full-scale test device, described previously by Martin et al. [2015a], and beginning a testing program to assess the behavior of shotcrete surface support reinforced with a variety of products including: fibers, chain-link mesh, welded-wire mesh, spray-on polyurea liners, and combinations of these products. This paper presents the findings of these tests."

Jan 1, 2016

The evaluation of Abandoned Mined Lands can involve the investigation of very large areas of land. Often, the locations of critical areas or impending problems are unknown, and are not easily identified from the surface. Microseismic monitoring has been demonstrated to be effective in identifying potential instabilities and active movement in mines from distances of several kilometers. By placing sensors in proximity to, or in contact with, a high acoustic conductance layer close to the mined zone, large areas can be monitored for potential problems with a minimum of sensors and drillholes. As part of a U.S. Bureau of Mines contract, a prototype system was developed to identify and locate potential instability problems over wide areas of land. Once a problem area has been located, the system can be used to analyze the type of the problem, its size, relative degree of instability, and potential for damage. Continued monitoring after application of remedial measures can effectively determine the efficacy of those measures.

Jan 1, 1993

By Mark A. White

Arch Mineral has developed several computer programs that aid the surface mine planning function. These programs are utilized to perform long term projections for various area or semi-area stripping operations. The program generated reports include yardage, tonnage, quality and ratio information for the user-specified time periods. The projections are used to anticipate the annual budget, to compare alternative mine plans and to analyze acquisition candidates. The programs are user friendly, fast and accurate. Geological Grid File Two data files must be set-up and used in conjunction with the mine planning programs. These are a geological data file and a general input file.

Jan 1, 1984

By G. ALBORNOZ, S. Utili, A. AGOSTI, C. VALDERRAMA, R. PELL

The steepness of an openpit mine’s slopes has a substantial influence on the mine’s financial return. This paper proposes a novel design methodology where overall steeper pitwalls are employed without compromising the safety of the mine. In current design practice, pitwall profiles are often planar in cross section within each rock layer: that is, the profile inclination across each layer tends to be constant. Here, instead, a new geotechnical software, OptimalSlope, is used to determine optimal pitwall profiles of depth-varying inclination. OptimalSlope seeks the solution of a mathematical optimization problem where the overall steepness of the pitwall, from crest to toe, is maximized for an assigned lithology, geotechnical properties and factor of safety (FoS).

By George J. Skoronski

The economics of pellet plant operation, in terms of fuel and power consumption, flexibility in the selection of the cheapest fuel source, system availability, maintenance costs, and the simplicity of process design, contribute to the determination of building and profitably operating a pellet plant. Design innovations, sup- ported by actual field data, have been initiated into the GRATE-KILN System design to positively address these factors. This paper presents the recent state of the art design concepts which have helped the GRATE- KILN System assume worldwide acceptance status.

Jan 1, 1983

By Allen Latham

It started' in 1936 when some Dutch adventurers wanted to scale the highest mountain in the South Pacific. Quite by accident, they discovered the Ertsberg, a contact deposit of magnetite laced with chalcopyrite, in a high mountain valley where it had been gouged at by glaciers and finally left as a solitary pillar for its discovery by a geologist who lent purpose to the expedition, Dr. J.J. Dozy. By the-.time a report was published describing the deposit, war had hit the Netherlands. Perhaps again by accident, the report was uncovered in 1959 by the East Borneo Company. At this point, Freeport entered the scene through its vice president for exploration, Forbes Wilson. During the course of a meeting on laterite prospects, the Ertsberg was introduced and he put the wheels into motion for Freeport to join in its exploration. You might, at this point, ask yourself whether you or your company would have taken on a venture to look at a reportedly large high grade copper outcrop in New Guinea, an unexplored land known best for its inhospitable climate, terrain and head-hunters. I heard the chief executive of one large mining company comment sometime back that neither he nor his company would have gotten involved. I won't attempt to describe the trials of the initial exploration expedition that passed through dense-man grove swamps, tropical jungle and across jagged mountains a distance of some 200 miles to get to the Ertsberg in 1960. It should be chronicled by its participants - Forbes Wilson, Del Flint, and John Bowenkamp. Needless to say, the participants relish the experience but wouldn't be among those volunteering for a return engagement. As a result, the Ertsberg changed from a reported outcrop to a mineral deposit containing an estimated 13 million tons with systematic surface sampling indicating a copper grade of over four percent. Moreover, the deposit extended to an indeterminate depth with the possibility of doubling or tripling. reserves well within reason.

Jan 1, 1971

By Brajendra Mishra, Himanshu Tanvar

Niobium and tantalum extraction industries heavily depend on fluoride chemistry for metal oxide production. This study concentrates on developing a fluoride-free approach utilizing alkali treatment for selective dissolution of niobium and tantalum phases. The application of microwave heating in the alkali treatment of columbite significantly reduced the processing time, providing a higher reaction rate and recovery than conventional heating. A short duration of microwave exposure (6 min) elevated the sample temperature to more than 900 °C, resulting in the rapid formation of water-soluble niobium and tantalum complex. Metal recovery from the solution was attempted through direct precipitation using guanidine carbonate as the precipitating agent, resulting in a mixed oxide product with > 90% purity. On the other hand, solvent extraction was also attempted using methyltrioctylammonium chloride as an extractant, providing a niobium oxide and tantalum-rich mixed oxide with > 98% purity as the final product.

Mar 23, 2024

By R. M. Powers

The Florida Institute of Phosphate Research (FIPR) has funded a four-year research project to develop a computer model 'which will predict the hydrologic impacts of phosphate mining on surface and groundwater systems. The core of the model is an analytical geographic information system (SPANS) which integrates EPA's Hydrology Simulation Program Fortran (HSPF) surface water model with the McDonald-Harbaugh groundwater model (MODFLOW). The hydrologic model conducts both event and continuous annual Simulations driven by variable precipitation and temperature data. The model is currently being calibrated and will be ready for distribution to the user community in mid-1991.

Jan 1, 1990

By Daniel A. Payne

For many years underground mining in the Sydney Coalfield has suffered from the effects of high horizontal stresses. It is only in the last 15 years that they have come to be recognized, understood, predicted and even avoided. This paper relates experiences in three coal mines in three different seams in the Sydney Coalfield. The effect of the direction of the principal horizontal stress on the direction of drivage of gate roads, access roadways and longwalls is described. Results of a monitoring program to measure the change of magnitude and direction of the principal horizontal stress in the gate roads as a result of longwall mining are also presented as well as the effect of the direction of principal horizontal stress on the shape of sandstone/gas outburst cavities.

Jan 1, 1998

By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Chloride ions and their interactions with two organic smoothing additives – Cyquest® N-900 and HydroStar® 4208 – during copper electrodeposition were explored using cyclic voltammetry and electrochemical impedance spectroscopy. The results revealed that chloride ions, up to a concentration of 40 mg/L, depolarized the copper deposition reaction. A combination of chloride ions and Cyquest N-900 inhibited the depolarization reaction during copper electrodeposition. It is proposed that the chloride ions acted as bridging ligands between copper and Cyquest N-900. Addition of HydroStar at a concentration of 2.5 mg/L depolarized the copper deposition reaction when no chloride ions were present. This behavior did not change with the addition of chloride ions at the concentrations tested, indicating that chloride ions and the polysaccharide do not interact.IntroductionElectrowinning is a major production method used to obtain high-purity copper. In modern tankhouses, copper is electrodeposited onto stainless steel blanks and then stripped, washed and bundled for delivery. Significant improvements in the quality of electrowon copper have been made over the last few decades. Additives, temperature, current density, electrolyte concentrations and agitation are known to influence the quality of copper electrodeposits (Jenkins and Eamon, 1990).The influence of chloride and organic additives on copper electrodeposition has been the subject of considerable research. The addition of small quantities of chloride and organic additives has been recognized to significantly improve the properties of copper electrodeposits. These additives are critical in the prevention of dendrite growth and the production of smooth, dense cathode deposits.Chloride ions have been reported to catalyze the copper reduction reaction and assist in the production of uniform deposits (Lakshmanan et al., 1977; Sun and O’Keefe, 1992). Moreover, it is generally agreed that chloride ions depolarize the copper deposition process at low (several millimolar) chloride concentrations. This is because chloride ions catalyze the reduction of copper (II) ions to copper (I) ions (Cu2+ ? Cu+ + e-) in the rate-limiting step of this process (O’Keefe and Hurst, 1978; Ilgar and O’Keefe, 1997; Hebert, 2005; Shao, Pattanaik and Zangari, 2007)."

Jan 1, 2016

By Thomas M. Lynberg

WIDCO is a surface coal mine located near Centralia, Washington. The WIDCO preparation plant processes over 7 million tons of run- of-mine coal each year with a product yield averaging 72%. In the jig type preparation plant the fine refuse amounts to approximately 130 dry tons per hour of 28mesh by 0. This fine refuse material is thickened in a 160ft. diameter static thickener with the use of lime as a coagulant and organic polymer as a flocculant. Once thickened the fine refuse, which is predominately bentonitic clays, has been dewatered and disposed of using several different methods. These methods will be discussed and include vacuum disc filters, ponds, solid bowl centrifuges, belt filter presses and experiments with electrokinetic dewatering.

Jan 1, 1981