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By J. A. Bartnik

In recent years, the need has become more and more accute for a high capacity, high intensity, wet magnetic separator for the concentration of finely ground, paramagnetic minerals. As a result of this increased interest, extensive test work has been conducted at our Central Test Laboratory, and the basic design for such a separator has been established. Three units have been developed to comprise a full line of this equipment: (a) Series 4L (laboratory), Figure I, is manually operated to permit maximum flexibility and precise control of each variable, with a capacity of 4 gallons per minute. (b) Series LOCC, Figure II, functions by automatically controlled feeding and washing cycles, and has a capacity of approximately 1.0 tons per hour. (c) Series 200CF, Figure III, basically consists of an annular pole box, rotating through the high intensity magnetic field. This unit has a capacity of approximately 20 tons per hour.

Jan 1, 1966

By W. Z. Choi

A model describing size reduction and mineral liberation during grinding has been extended to include multiple classes of composite particles. The majority of the model parameters have been directly determined using computerized image processing equipment to analyze the products from batch grinding tests. A coarse-grained sphalerite ore from Tennessee, representing a nearly ideal binary mixture of sphalerite and dolomite, has been used to experimentally validate the model for the case of dry, batch grinding. In all cases, excellent agreement has been observed between the model predictions and the experimental results.

Jan 1, 1986

The authors provide a discussion of the paper, ?Coal workers? pneumoconiosis prevalence disparity between australia and the united States,? a peer-reviewed paper that appeared in the technical papers section of the July 2012 issue of Mining Engineering magazine. The original authors, G.J. Joy (gjoy@cdc.gov), J.F. Colinet (jcolinet@cdc.gov) and D.D. Landen (dlanden@cdc.gov), respond.

Jan 1, 2013

By P. A. Lindberg

Early Proterozoic ore deposits in the Verde district at Jerome, Arizona have produced 33.7 million metric tons of ore (1893-1975). The United Verde and United Verde Extension deposits produced most of the ore that yielded 1,644,323,100 kg Cu plus large amounts of Au, Ag, and Zn. These deposits are situated on the fractured and hydrothermally altered apex of a large submarine rhyolitic extrusive (Cleopatra formation). Precambrian lithologies are penetratively deformed and at Jerome the Fl folds plunge steep to the NNW. For the past two decades the volcanogenic model has superseded the replacement theory of ore formation.

Jan 1, 1992

By Y. B. He

The effect of the overflow to underflow (O/U) flowrate ratio of a dense medium cyclone on its performance is tested utilizing a 6" dense medium cyclone and density tracers. The results show that the O/U flowrate ratio is clearly correlated with the separation cut point D50, the separation efficiency Ep, the density differential 0, and short circuiting of the cyclone. Within certain limits, a higher O/U ratio results in a better separation efficiency, a higher D50 and an increased density differential. A lower O/U ratio, on the other hand, reduces the cut point shift and density differential. The phenomenon of short circuiting to the underflow, which is especially significant for fine particles, is directly connected with an excessively low O/U ratio.

Jan 1, 1992

By J. W. Rains

Arizona Portland Cement Company's limestone deposit (called Twin Peaks) is approximately 4 miles southeast of the cement plant. The pant is adjacent to both the Southern Pacific Railroad and Interstate 10, about 17 miles northwest of Tucson. Placer claims were filed on the Twin Peaks deposits in 1923. From that time until the present, geologic data have been accumulated and evaluated to define more closely the quantity and quality of the limestones. The cement plant at Rillito was originally constructed as a one-kiln plant in 1949. Capacity was increased in 1952 and 1956, bringing the plant to an annual capacity of 44,000 tons of cement. In 1972 anther expansion program was completed, bringing annual cement capacity to 1.1 million tons. Geologically, the Twin Peaks contain formations ranging from the Precambrian Pinal Schist to the Pennsylvanian Naco Formation. Within this sequence, other exposed formations include the Cambrian Bolsa Quartzite and Abrigo Formation, Devonian Martin Limestone, Mississippian Escabrosa Limestone, and Pennsylvanian Naco Formation. Generally, the Escabrosa, Naco, and Martin Formation are the primary sources of limestone for manufacturing cement. The Martin Formation is basically a dolomite with bands of limestone, quartzite, and siltstone. These limestones are blended with outside source materials (clay and iron ore) to make a raw mix that will make specification cements. Several drilling programs were initiated between June 1946 and March 1982. Information derived from these programs provided the means to develop cross sections, geologic blocks, and grade blocks. The configurations of the geologic and grade blocks are the same. Block boundaries delineate the various formations on any particular level. Cursory inspection of the structure would indicate a broad syncline elevated on the west side. A more detailed examination shows that the structure has been complicated by several periods of faulting and intrusion of igneous rocks.

Jan 1, 1987

By Francesco Chiappalone, Miriam Piemontese, Lance Waddel, Paolo Perazzelli, Emidio Tamburri, Roberto Schuerch

The Three Rivers Protection & Overflow Reduction Tunnel is part of the Long-Term Control Plan of the City of Fort Wayne, Indiana (USA). The 4.9 m internal diameter tunnel, of length approximately 7.5 km, is excavated at a depth of approximately 40–60 m through carbonate rocks using a slurry TBM. Due to the high hydraulic conductivity of the rock mass and the high in-situ ground water pressure (up to 6.5 bar), the management of the water inflow during the TBM advance and standstills, represents the major challenge for the project. This paper outlines the geotechnical conditions and the hazards related to the large water inflows expected in the pre-excavation phase and discusses the experience gained during the construction of the first 8,224 feet (2,507 m), (first third of the total length of the tunnel).

Jun 13, 2021

By H. Colijn

The trend in the coal industry for many years has been to make everything "bigger and faster" This also held true for loading and storage facilities. Where once a million ton per year mine was rare, three to five million ton per year mines are not uncommon today in the bituminous industry. This greatly increased production, made possible through mechanization, required greatly improved loading facilities just to get the coal away from the mine. Also, there is a trend toward combining production from more than one mine and cleaning it in a single preparation plant. In addition to increased loading capacity, this frequently necessitates raw coal storage and blending facilities. The development of the unit train, more than any other factor, has contributed to the widespread construction of storage and high-speed loading facilities for clean coal. In the export market, the construction of ever larger coal bulk carriers has contributed to a need for faster and larger loading facilities at ports. The present engineering and construction cost of these larger facilities make it essential that the flow and handling properties of the particular coals are fully known. These properties can be measured well in advance and the proper design criteria established. This eliminates costly surprises later on during start-up and operations. This paper will review coal and coal refuse properties, such as shear strength, cohesion, friability, and the flowability of coal and how they affect the design criteria of storage silos.

Jan 1, 1979

By J. K. Ross, K. O. Hoal, S. K. Appleby

Understanding ore variability is a key factor in the geometallurgical analysis of a deposit and is beneficial to process development and mine planning. Ore variability is a function of the mineralogy of a deposit, in terms of both ore and gangue minerals and their textural relationships. This study integrates optical microscopy and quantitative mineral analysis to characterize the mineralogy and texture from 13 samples from different lithologic units at the Bingham Canyon Mine. The analysis identified several parameters, such as modal mineralogy, alteration assemblages, distribution of mineral phases and alteration assemblages and microfracture and void space distribution. These parameters can have an impact on the materials’ behavior during processing. This study demonstrates that quantitative mineralogical analysis can provide detailed information for improved understanding of ore variability.

Jan 1, 2010

By T. Szwilski

The Appalachian coal region is an area here the small mining operation dominates. The large number of small operations makes the coal industry in chat area very competitive, the industry concentration ratio being low. This feature is reflected in the nature and behavior of the coal supply and demand viz a viz the coal market. The vast majority of the small coal operations in Eastern Kentucky for example, are contractors. The circumstances under which a large mining company can elect to use contractors to supplement their coal production are examined. The pros and cons of small underground single unit mines and larger multiple unit mines are discussed.

Jan 1, 1986

By Thomas Konstantis, Spyridon Konstantis, Panagiotis Spyridis

"Tunneling and Underground works are unequivocally subject to a diversity of inherent uncertainties associated with the geotechnical, hydro-geological and environmental regime that surrounds them. On many occasions, these uncertainties can provoke loss events of considerable consequences. The present contribution elaborates on losses that the insurance market has suffered in the recent years, following a construction failure event. These losses are being considered and analysed on a quantitative basis through evaluation of cost related data, with explicit discretization of the applied construction methodology and of the subsequent developed failure type since both of which are considered of major importance. Given the identified persistence and regularity of some loss-contributing factors, recommendations are provided on the basis of a proactive risk engineering management approach that are envisaged to reinforce the understanding of project risks and alleviate the incurred insurance cost. 1 INTRODUCTION The underground construction sector has always been a very challenging area for all involved parties, including the insurance market. Main reason for that remains the uniqueness of the uncertainties sources and the subsequent inherent risks that the tunneling and underground projects are exposed to. In many instances, these risks materialize, leading to loss events with substantially high impact on reinstatement cost and incurred delays, which depending among others on the insurance coverage will have to be bared by the Insurance market. In the recent decades and as the tunneling industry boomed and expanded with many major and significant projects undertaken around the world, the insurance market was faced with additional challenges. Increased competition during tender coupled with the scale and complexity of the projects and politically driven decision making exerted pressure on the project timelines, completion dates and budget. The pressure for on-time or even early project completion- to avoid liquidated damages or achieve bonus payments, respectively- along with cost reduction efforts and the incentive for innovative failure events. That, in turn, put additional pressure on the Insurance market which had experienced a significant amount of losses with substantial cost. One of the triggered mitigation actions was the introduction of the Code of Practice for Risk Management of Tunnel Works (ITIG, 2006 & 2012; MunichRe 2006, Wannick, 2007, Spencer, 2008, Adeyemo, 2011)."

Jan 1, 2016

By C. McAllister, D. Preece, J. Berendzen

"The Multiple Blasthole Fragmentation (MBF) model models multiple explosive charge contributions and the effect on fragmentation of delay timing with its associated scatter for each blasthole. The model uses near-field blast vibration attenuation parameters and the ground p-wave velocity as inputs for part of the in situ rock property to model rock fragmentation. It models most blast design parameters explicitly and simulates the effect of wave reinforcement due to the interaction of simultaneously arriving waves or diminishing cooperative contribution from long delay intervals between charges within a blasthole or among blastholes. The fragmentation size is calculated at three-dimensional grid points within a blast, and the fines and oversized blocks are treated explicitly. The model takes a surveyed irregular geometry of the free face of a blast as the calculation boundary.This paper presents a case study on applying the MBF model at an openpit mine. Near-field vibration measurements from signature hole blasts were conducted to obtain the stress-wave magnitude and attenuation parameters as well as ground sonic velocity. A production blast was then monitored with the corresponding fragmentation measured, serving as site-specific inputs to the MBF model. Various blast design scenarios were then simulated to develop ones that provide better fragmentation to improve mill throughput for the mine. IntroductionThe semiempirical fragmentation models currently found in the literature (Cunningham, 1987; Lownds, 1995) cannot explicitly model contributions from multiple blastholes with varying delay intervals. Most of these models are not three-dimensional. Furthermore, these models predict an average fragmentation size within a volume surrounding a blasthole and use the average size to generate a size distribution over the volume. The percentage of fines and oversize blocks is included in the distribution. Typically, such models are inadequate for predicting fines and oversize blocks (Cunningham, 1987)."

Oct 1, 2016

By Syd S. Peng

In the past few years, the numbers of underground coal mines in this country using longwa11 mining method have been dramatically increased. In the latest count there are approximately 90 10ngwa11 faces amounting roughly 8% of the total underground production. Meanwhile, shortwall mining adapting longwa11 powered supports to 'coal mining and handling systems in room and pillar mining is also gaining importance in the Appalachian coal field. Although there are only 7 operating shortwall faces so far, indications are that it will be increasing steadily. Modern longwall faces are highly mechanized and productive. One of these key elements that contribute to the success of modern longwall mining is self-advanced powered supports. There are several types of powered supports. Frame type is two sets of one to four hydraulic legs supporting beam-type roof canopy and floor base. However, chock type is more popular and connected to broad roof and base structure. Shield supports were introduced recently but proved to be highly successful (1). A shield support consists of two hydraulic jacks mounted between a base plate and a gob shield. The base plate is hinged to gob shield which is in turn hinged to roof canopy.

Jan 1, 1977

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jason Navoyski, Jennica L. Bellanca

Haul truck fatal accidents and injuries continue to be a significant concern for the mining industry. However, the availability of high-quality training materials continues to be limited. Near-miss incident accounts, if packaged well, could help fill this gap, because for every fatality, there are hundreds of reportable accidents and thousands of undocumented near misses. Researchers from the National Institute for Occupational Safety and Health (NIOSH) collected detailed accounts of 21 near-miss incidents in virtual interviews with mineworkers at surface mining operations across the country. From these interviews, researchers created four simulation videos using the Unity game engine. The simulation videos bring these events to life through first-person retelling and various visual perspectives of actual events. Each video exemplifies a critical safety message and a common haul truck hazard. This paper describes the process of taking narratives and turning them into impactful visual stories using graphic simulation. NIOSH plans to co-release these simulation videos with the Mine Safety and Health Administration (MSHA) to the mining industry to raise awareness and ultimately help reduce haul truck-related accidents and fatalities in mining.

Jun 1, 2023

By R. N. Browne

As man searches unexplored horizons for new and economic industry, he must be constantly and acutely aware of the presence or absence of that precious commodity without which Industry, indeed Man himself, could not survive --W ATE R. The water requirements of the world today are magnanimous, considering that in 1960 the estimated consumption in the united States was over 300 billion GPD (1) or more than 1,700 GPD per person (5). The magnitude of the problem can be visualized as one considers that three times this quantity of water will be required in the united States by the year 2 000, when the dependable supplies of water are estimated to be only two-thirds of that required(2). How, then, can we continue to wreak such havoc on that life-sustaining substance -W ATE R? It is necessary, indeed mandatory, that those engaged in the Engineering profession consider it their moral obligation, not only to conserve the quantity of water which their conceived projects may require, but also to treat the effluent in order that the eutro-phication of natural water courses not be abnormally accelerated. The International Nickel Company of Canada Limited consumes some 33-1/2 millions of gallons of fresh water daily at its nine town-sites, fourteen mines and eight plants throughout the Sudbury district of Ontario. The present daily reuse of water exceeds 100 millions of gallons in the same area. It is noteworthy to mention that the milling rate has increased from 46,000 to 70,000 tons per day during the past five years, with no increase in water consumption. In fact, there has been a reduction in fresh water requirements.

Jan 1, 1971

By Ben L. Seegmiller

The artificial stabilization of a pit slope at the Twin Buttes Mine near Tucson, Arizona has been completed as part of a practical rock mechanics program. The research program began in June 1971 as a result of the three million ton South Slope slide(1) which caused significant economic and operational problems. Hydrological studies, field and laboratory testing and investigation of various stabilization systems(2)occupied the first year of research. In July 1972 a design for an artificial stabilization test using post-tensioned cable bolts was completed and the selection of an outside contractor was made the following month. The project began in mid-September and was completed during the first week of January 1973. The test site is located adjacent to the South Slope slide in a zone of high potential failure. When the site was initially selected it was thought that it would remain stable at least until the test could be completed. However, heavy rains which fell in late October induced displacement in the half of the test site adjacent to the South Slope slide. Prior to this stabilization test it was thought both impractical as well as improbable that a moving slide could be stabilized with an artificial support system(3). Because the project was nearing the half-way point it was decided that an attempt should be made to complete the test as originally planned. This meant, in effect, that an attempt would be made to stabilize the moving section as well as the stable section.

Jan 1, 1973

By K. Awuah-Offei, A. U. Rehman

"Information diffusion potential of a social media user affects how quickly information about a mineral project can diffuse through that user. If management can use social media and network analysis, in community engagement program, to understand how fast and how far information will diffuse to communities and followers of particular social media users, it can selectively focus on the most influential users. This paper proposes a method to examine the information diffusion potential of social media accounts. The work uses Gephi, an open source software, to extract and analyze data from different Twitter handles to predict their information diffusion potential. The work uses case studies of real Twitter users (e.g. mining news organizations and bloggers) associated with mining to illustrate the approach. The case study results show that there are significant disparities in information diffusion potential that will demand selective attention. This research will help mines develop effective social media engagement strategies. INTRODUCTION The mineral industry provides raw material for industrial activity to support our society (Martens and Rattmann, 2001). Mines have changed conventional mining practices to sustainable ones because of the negative impacts of mining and increased public awareness (Wang et al 2016). The concept of sustainable mining is getting mature as stakeholders (e.g., governments, investors and host communities) are getting involved in mining projects (World Economic Forum, 2014). The failure of mining companies to address the demands of these stakeholders might result in failure to acquire social license to operate (Thomson and Boutilier, 2011). The social license to operate (SLO), if granted, is mutually beneficial to all stakeholders. Mines prefer being granted SLO and keeping it to avoid any kind of social unrest due to their operation (Prno, 2013; Moffat and Zhang, 2014). Mining communities can grant different levels of SLO; ranging from withholding SLO to psychologically identifying with the project (Joyce and Thomson, 2000; Thomsan and Boutilier, 2011). Most of the previous work to understand community perceptions and SLO in mining is generally qualitative (ICMM, 2012a; Thomson and Boutilier, 2011; Prno, 2013; Moffat and Zhang, 2014; IFC, 2014). In particular, there is limited work on how community perceptions change over time due to information diffusion (Boateng and Awuah-Offei, 2017). However, SLO changes with respect to time (Yates and Horvath, 2013), which can result in risks that are not easy to predict. Mine managers and engineers have a desire to understand these changes so as to mitigate these risks (Que and Awuah-Offei, 2014; Que et al., 2015)."

Jan 1, 2018

By A. Janwong

Ion exchange technology is becoming more prevalent for metal recovery from low concentration solutions. The products of ion exchange are typically a metal free stream (product stream) and a concentrated metal stream (byproduct). The metals in the concentrate stream are usually precipitated and returned to the process or discarded. The unique features of emew® technology enable metals to be recovered directly from the concentrated stream. The advantage of the IX-emew® combination is the ability to have two product streams: 1) clean metal free solution and 2) metal product for sale. In addition to recovering metals from solution, it is also possible to separate metals from each other and recover more than one metal product. In this paper, examples of IX-emew® combinations are detailed including the recovery of copper, nickel and cobalt from an industrial waste stream, recovery of nickel from a spent electroless nickel plating solution and recovery of cobalt from an hydroxide cake.

Feb 23, 2014

By James R. Yancik

Economical and environmental pressures necessitates the recovery of the minus 0.6 mm x 0 coal generated by todays mining machines. This size fraction, dependent on the type of production unit, maintenance of the production unit, and the Hardgrove Grindability Index, can be a substantial portion of the Preparation Plant feed. Historically, dewatering of the collected 0.6 mm x 0 product has often been rather expensive and marginal with respect to surface moisture reduction. The Freeman United Crown II Preparation Plant more than adequately demonstrates that the continuous scroll type centrifuge can dewater 0.6 mm x 0 coal to acceptable surface moisture levels.

Jan 1, 1981

By Ted T. Biddle

The world energy crisis has created a greatly expanded exploration program for energy fuels. The demand for materials required for drilling operations such as barite, which is the primary component of drilling fluids, has increased proportionally. As in the case of many other minerals, existing high grade barite mines are no longer capable of producing the required tonnage. Consequently, exploration and development of lower grade ore bodies has been increased. The need to produce a high quality product at maximum recovery rates, along with the ever changing economics affecting both selling price and production costs has triggered accelerated research programs toward more sophisticated and efficient beneficiation methods. Taking into account the specific gravity differential between barite (4.5) and the normal gangue minerals such as silica and calcite (2.7), gravity concentration methods are the prime consideration with flotation as a scavenging process. Greater emphasis on particle size liberation, size reduction and concentration is also indicated. In order to accomplish these objectives, it has been necessary to revert back to the old adage, "Recover your minerals as soon as they are free."

Jan 1, 1980