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By Vinícius Resende Domingues, André Pacheco de Assis, Bernardo Cascão Pires e Albuquerque

"The increasing demand for underground works in urban centers, and in particular the need to build undercrossing tunnels, requires constant evolution in building techniques in order to achieve success and safety. In the case of Brasilia, capital of Brazil, in order to preserve an important avenue (Eixo Monumental), where are located many historical monuments, the construction of a tunnel was envisioned as an option to interconnect the National Stadium (on one side of the avenue) to the Convention Center Ulysses Guimarães (on the other side). The excavation design is comprised of a coverage smaller than one diameter, height of 7.5 m, width of 9.0 m and length of 25 m. In order to enable a negligible influence on the avenue’s usage, the structure is designed as a portico system composed of pipe canopy. In this context, this study presents the portico analytical solution computed with the aid of the software Mathematica and a numerical solution using the software ABAQUS. INTRODUCTION Undercrossing tunnels are increasingly common in urban centers as alternative roads or as access to underground works of large dimensions (stations and parking lots). The geomechanical conditions of the soil mass, not always favorable, and the low distance between tunnel’s ceiling and the surface require intense treatment of the soil massif and execution of a rigid support system. The importance of the road just above the undercrossing tunnel emphasizes the need for a highly competent monitoring system because existing structures require minimum allowable displacement and do not allow the interruption of traffic. The soils that are excavated for the construction of undercrossing tunnels are composed, in most cases, of layers of fill and / or soft soil or weak rock, showing stability problems when subjected to tunneling operations. The combination of low coverage and week ground is solved by soil improvement techniques and strengthening of the excavated cross-section with further advance with the so-called New Austrian Tunneling Method (NATM). Another option is to build structural frames that support the surface. In this research, and based on the context of a case study, we propose the study of the construction technique comprising a portico structure composed of pipe canopy. For this paper, the technical standards used are the Brazilian ones as the case study refers to this country."

Jan 1, 2016

By Fouad Faraj

For every blast pattern, zones of unique material types need to be classified before mining. Most material types can be summarized into different kinds of ore and waste. Blocks generated from blasthole assays are too small to be selectively mined, so areas with a single material classification meeting the mine’s selective mining unit must be defined. Current industry standard practices are to manually draw ore/waste dig limits, but this process is subjective and results in quantities of dilution and ore loss that can be improved upon to enhance the profitability of mining operations. In this study, two weeks of production data from a homogeneous copper (Cu) porphyry and heterogeneous manto-type Cu deposit were used to assess the variability in the hand-drawn dig limits of 20 geologists, mining engineers and ore control specialists, which were compared with the optimal ore/waste delineation. The profit for 20 distinct hand-drawn dig limits for the homogeneous mine varied by 3.7 percent, from $10.5 million to $10.9 million, averaging at $10.8 million. The percentage was nearly double for the more heterogeneous mine at 5.9 percent, from $17.9 million to $19.0 million, averaging at $18.6 million. Using the optimal ore waste delineation, the profit increased to $11.0 million (1.9 percent increase) and $19.3 million (7.0 percent increase) for the homogeneous and heterogeneous deposit, respectively. The natural variability, diggability requirement and selectivity are identified as the main drivers of ore loss and dilution. Recommendations are provided for reducing the subjectivity in manual hand-drawn dig limits by integrating dig limit optimization algorithms as a tool to assist practitioners.

Oct 1, 2024

By T. McWaters

Miami Copper Company began a block-caving operation in 1911 using a gravity mill to separate copper minerals from the Pinal Schist host rock. The tailing was deposited by the upstream method using perimeter launders and spigot valves in six canyons adjacent to the mill until 1932. In 1928 the larger and more distant Solitude tailing pile was developed which by 1932 was receiving all tailing except for upsets. In 1925 Miami Copper converted its gravity mill to flotation which began to produce higher sulfide copper recoveries.

Jan 1, 1990

By Drew Hobert, John Nielson, Erich Dohm

Metallurgical coal is an essential component for the blast furnace-basic oxygen furnace (BF-BOF) steelmaking process, which accounts for roughly 70% of total global steel production. To meet the growing demand for metallurgical coal, Arch Resources identified the potential to recover low- ash coal from ultra-fines discarded prior to the deslime flotation circuit across their portfolio of operations. Historically, many flotation circuits were designed to discard this ultra-fine coal due to high clay content and technological barriers to cost-effectively upgrade and dewater the coal to a saleable product. Recent advancements in high-intensity flotation technology, including the Eriez StackCell, have enabled coal producers to recover ultra-fine coal while minimizing capital and operating costs. In July 2023, Arch Resources commissioned the first full-scale ultra-fines recovery circuit utilizing StackCell high-intensity flotation technology at the Leer Mining Complex. This paper reviews the approach utilized to develop the flotation process design, learnings from the commissioning and ramp-up period, and performance data through the first year of operation.

Feb 1, 2025

By B. A. Carbon

Western Australia is the largest state in Australia with an area one and three quarter times the size of Texas. Most of the State is desert or semi-desert, and only the southwest corner is heavily populated. The State has a population of one and a half million people, and one million of these live in and around the city of Perth. Perth is located on the narrow Swan Coastal Plain and is flanked by the Indian Ocean and the Darling Plateau. The Darling Plateau is an ancient peneplain rising some 300 metres above sea level, and forms an important resource base for the population.

Jan 1, 1984

By Sebastian Avalos, Julian M. Ortiz, Willy Kracht

Semi-autogenous grinding mills play a critical role in the processing stage of many mining operations. They are also one of the most intensive energy consumers of the entire process. Current forecasting techniques of energy consumption base their inferences on feeding ore mineralogical features, SAG dimensions, and operational variables. Experts recognize their capabilities to provide adequate guidelines but also their lack of accuracy when real-time forecasting is desired. As an alternative, we propose the use of real-time operational variables (feed tonnage, bearing pressure, and spindle speed) to forecast the upcoming energy consumption via machine learning and deep learning techniques. Several predictive methods were studied: polynomial regression, k-nearest neighbor, support vector machine, multilayer perceptron, long short-term memory, and gated recurrent units. A step-by-step workflow on how to deal with real datasets, and how to find optimum models and final model selection is presented. In particular, recurrent neural networks achieved the best forecasting metrics in the energy consumption prediction task. The workflow has the potential of being extended to any other temporal and multivariate mineral processing datasets.

Jun 16, 2020

By Jerry C. Tien

Without a doubt, the scope of China?s coal boom has been nonstop. Despite the world economic slowdown, China?s year-on-year gross domestic product (GDP) jumped 10.3 percent year-on-year in 2010, boosted by a faster than expected 9.8 percent expansion in the fourth [ ] quarter. And, the first quarter of 2011 expanded another 9.7 percent. According to a frequently cited statistic, the country is building two mid-sized coal plants each week. This amounts to a yearly increase equivalent to the entire power grid in the United Kingdom. China?s coal production was doubled in the last 10 years, from 1.044 Gt (1.15 billion st) in 1999 to 3.2 Gt (3.52 billion st) in 2010. This is 3.2 times the U.S. production (986 Mt or 1.085 billion st) and nearly half (46.3 percent) of the world?s total coal production (6.91 Gt or 7.6 billion st). This rapid increase of demand for coal has made China the world?s largest coal importer in 2009. With the economic situation improving, this trend is expected to continue.

Jan 1, 2011

By J. H. Kempton, D. Atkins

Predictions of delayed environmental impacts from mining—degradation that won’t begin for hundreds of years, but will then continue for thousands—present new permitting challenges. Examples include evaporative concentration in pit lakes, which can eventually cause metals concentrations to exceed human and wildlife toxicity standards, and delayed degradation of groundwater by slow moisture percolation through acid-generating tailings and waste rock. Given the time-value of money, the present worth of such delayed impacts is insignificant, yet they are unacceptable undercurrent laws and cultural values. Long-term financial set-asides offer a possible solution, first funding infrequent, long-term monitoring, followed by more expensive mitigation when the set-aside has matured.

Jan 1, 2000

By D. Parks, A. Miller, M. McNinch, R. Jacksha, H. Nickerson

Each year hundreds of mine workers are involved in machinery-related accidents. Many of these accidents involve inadequate or improper use of lockout/tagout (LOTO) procedures. To mitigate the occurrence of these accidents, new safety methods are needed to monitor access to hazardous areas around operating machinery, improve documentation/monitoring of maintenance that requires shutdown of the machinery, and prevent unexpected startup or movement during machine maintenance activities. The National Institute for Occupational Safety and Health (NIOSH) is currently researching the application of Internet of Things (IoT) technologies to provide intelligent machine monitoring as part of a comprehensive LOTO program. This paper introduces NIOSH’s implementation of an IoT-based intelligent machine monitoring system to improve safety during operation and maintenance at a concrete batch plant. INTRODUCTION Of the hundreds of machinery-related accidents occurring every year in the mining industry, incidents involving stationary machinery at surface mines continue to be amongst the most frequent [1]. A National Institute for Occupational Safety and Health (NIOSH) study showed that the majority of fatal accidents involving stationary machinery at surface mines occurred at sand and gravel (38%) and stone (26%) operations. Of these accidents, entanglement in conveyor components were the most common cause of fatal accidents (48%) [2]. The same study stated that one-third of these accidents involved improper lockout/tagout (LOTO) procedures as a contributing factor. The U.S. Mine Safety and Health Administration (MSHA) acknowledged this problem, stating in a recent request for information (RFI) [3]: “Since 2007, there have been 17 fatalities related to working near or around belt conveyors, of which 76 percent were related to miners becoming entangled in belt drives, belt rollers, and discharge points. Factors that contribute to entanglement hazards include inadequate or missing guards, inadequate or an insufficient number of crossovers in strategic locations, and/or inappropriate lock out/tag out procedures. Systems that can sense a miner's presence in hazardous locations; ensure that machine guards are properly secured in place; and/or ensure machines are properly locked out and tagged out during maintenance would reduce fatalities [3].” In response to this problem, NIOSH’s Spokane Mining Research Division (SMRD) is exploring the potential application of Internet of Things (IoT) technologies to provide cost-effective intelligent machine monitoring systems for improved worker safety [4, 5]. SMRD partnered with Central Pre-mix CRH Company (Central Pre-mix) to develop and install a proof-of-concept wireless IoT solution to monitor machinery and conveyors during operation and maintenance. The primary goals of the system were to provide real-time monitoring of access points and facilitate the planning and execution of LOTO procedures

Jan 1, 2019

By R. L. Grayson

Focusing on relationships between severity measure versus productivity and other factors, this paper presents a comprehensive study of injuries for U.S. underground coal mines in 1996 by mine size. Based on analyses of data, generally the larger the mine, the more productive it is (in tons per employee-hour), but the more severe is its injury experience (r = 0.65). Within very large, large, and medium mine sizes, however, the more productive the mine, the less severe is its injury experience (r =-0.43, -0.36, and -0.26, respectively). For small and very small mines, a more deeply nested analysis is required to understand relationships. Other interesting relationships and comparisons are presented.

Jan 1, 2000

By S. H. Seyedein, Hamed Tavakkoli, Mohammad Reza Aboutalebi, S. N. Asharafizadeh

The liquid–liquid extraction behavior of lutetium from different acidic solutions was investigated using two extractants, D2EHPA and PC88A, in kerosene. Lutetium extraction reactions with D2EHPA and PC88A from HNO3 and H2SO4 solutions were chemically and thermodynamically analyzed. It was found that each Lu cation was complexed with six monomers of the organic extractant and released three protons. Simultaneously, the Lu cation was instituted in the P–O–H group of the extractants. Thermodynamic analysis of reactions between extractants and acidic solutions showed that the D2EHPA-HNO3 system is the most favorable for extracting lutetium. It is noted that the calculated equilibrium constant of the reaction in this system was approximately six times larger than that of the D2EHPA-H2SO4 system. However, the value of the equilibrium constant for the D2EHPA-HNO3 system was evaluated to be approximately 200 times greater than that of the PC88A-HNO3 system. Therefore, one can conclude that the extraction behavior of lutetium is more influenced by the extractant type than the solutionmedium. The synergistic effect of different mixtures of extractants on the solvent extraction of lutetium was also examined, and the highest synergistic factor was obtained for a binary mixture of PC88A:D2EHPA at the ratio of 4:1 for both aqueous solutions.

Mar 15, 2021

By W. M. Houston

The phosphate formations of the Pliocene epoch were deposited along the coastal shelf of the eastern seaboard. The deposition of the phosphate is thought to be somewhat contiguous along the early shoreline, and the deposit can be more or less traced over an 800 to 930 mile path from the Florida Gulf Coast, near Ft. Myers, to the Pamlico Sound of North Carolina. This is illustrated in Figure 1. Three areas of commercial importance are currently being exploited from this extensive known deposit: 1 - The so-called ?Bone valley? in Central Florida (multiple operations) 2 - Hamilton County in North Florida (Occidental Corporation operation) 3 - Beaufort County in North Carolina (Texas Gulf Sulphur operation)

Jan 1, 1966

By M. du Plessis, J. P. Gouvea

Mesh based areal support is commonly applied in South-African deep-level gold mines. It forms part of an integrated support system that can cater for both rockfall and rockburst incidents. The application has been successfully applied over many years. Operations have different geotechnical conditions and practical considerations, which has led to the development of various types of mesh and integrated mesh-based support systems (i.e. meshing and lacing versus welded or chain-link mesh sheets). Typically rolls or sheets of mesh is pinned with rockbolts to the surface of an exposed excavation. Applications vary from hangingwall coverage in a conventional stope gully to complete excavation coverage in footwall drives of conventional mines or on-reef drives in massive mechanised mines. It is however critical to understand the behaviour of the rockmass and apply suitable support systems.

Apr 26, 2022

Commercialisation of outcomes from research projects is a process often poorly understood and managed, but has the potential to achieve significant benefits for the industry and community as a whole. JKTech Pty Ltd was established in 1986 to transfer viable research outcomes from the Julius Kruttschnitt Mineral Research Centre (JKMRC) at The University of Queensland, Australia. This paper describes successful and unsuccessful examples of commercialisation by JKTech over the years, and draws some conclusions as to the factors that contribute to success and failure in technology transfer.

Jan 1, 2012

By Caroline L. Herzenberg

Recently, neutron-induced gamma spectrometry has been introduced and gained provisional acceptance as a method for continuous automated analysis of coal. Instrumentation based on this technique has been under development for and in testing at coal preparation plants and a coal gasifier. To provide a deeper understanding of, and extended capability in applying this method, theoretical calculations have been performed of the absorption of thermal neutrons by various coal compositions, and the thermal neutron capture prompt gamma emission spectra produced by these compositions have been calculated. Selected results of these computer calculations and the computer generated spectra are presented.

Jan 1, 1984

By F. Nelson

RJB Mining is the largest coal producer in the UK. In January 1995 the Company acquired the Central North and Central South Regions of British Coal consisting of: ? 15 operating collieries -including capital equipment ? 2 care and maintenance mines ? 16 operating Opencast sites ? Interest in 26 prospective and 46 potential Opencast sites ? Approximately 417 million tonnes of proven and probable reserves and considerable mineral resource ? 9 million tonnes of coal stocks ? Long term contracts to supply approximately 90 million tonnes of coal to National Power and PowerGen to the period of 3 March 1998 ?Approximately 7,600 employees and 4,500 mining contractual labour. Up to the acquisition RJB Mining had the capacity to produce 14 million tonnes of saleable output with an approximate 1,500 strong workforce.

Jan 1, 1998

By S. G. Sawyer

The Pittsburgh Safety and Health Technology Center (PSHTC) of the Mine Safety and Health Administration (MSHA) provides engineering and scientific support to the inspectorate personnel of MSHA. One of the Center's myriad roles is to assist in the investigation of mining accidents, especially those involving fatalities. Center personnel utilize forensics to help uncover the causes of accidents and to make technical recommendations on the prevention of future similar mishaps. To exemplify a typical forensic investigation, this paper documents the methodology used in determining the reasons for a boat sinking, which resulted in a double fatality on a mine company pond.

Jan 1, 1997

By N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities during 2017 draws upon information from industry sources, published literature, SNL Metals & Mining (SNL), an offering of S&P Global Market Intelligence (New York, NY) and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. Three types of information are reported and analyzed in this annual review of international exploration: 1) budgetary statistics expressed in U.S. dollars provided by SNL; 2) regional and site-specific exploration activities that took place in 2017 as compiled by the USGS and 3) regional events and legislation that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources were used to develop commodity and regional compilations, statistics may vary depending on the source and type of data that are being reported.The SNL data summarize budget estimates for worldwide exploration activities in 2017 for 30 nonfuel mineral commodities and metal alloys, based on company surveys. Surveys focused on precious metals (gold, platinumgroup metals (PGMs) and silver), base metals (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (bauxite, chromite, iron ore, manganese, phosphate and potash), and other commodities (aluminum, antimony, diamond, graphite, heavy-mineral sands, lithium, niobium, rare-earth elements (REEs), scandium, tantalum, tungsten, uranium, vanadium and yttrium). Information on uranium exploration activities was included in SNL’s survey for the first time in 2007. Data on lithium, niobium, phosphate, potash, REE and tungsten were compiled for the first time in 2010, and scandium, vanadium and yttrium were added in 2014 because of their increased topical significance. Since 1999, companies with exploration budgets of $100,000 and greater were included in the SNL surveys. SNL budget estimates exclude coal, and oil and gas. The 2017 SNL mining company survey compilation was reported by SNL to include an estimated 95 percent of the world’s nonfuel mineral exploration budgets. The 5 percent that was not covered was accounted for by companies that chose not to participate in the SNL survey, private companies that do not publish their budget data, and government-funded exploration activities."

Jan 5, 2018

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

3.1 INTRODUCTION The final subsidence basin discussed so far is that developed long after mining has stopped. In a supercritical final subsidence basin, the central portion subsides uniformly. Thus any structures located there are not subjected to any final permanent surface deformation. But this statement is only true for the final subsidence basin. When the face is moving, the structures are subjected to dynamic deformations associated with the dynamic subsidence basin. For instance the house in front of a moving face (location 1 in Fig. 3.1) is subjected to the maximum tensile strain and the maximum positive curvahue. When it falls behind the face in location 2, it is subjected to the maximum compressive strain and the maximum negative curvature. When the house is far behind the face in location 3, it returns to its original condition with only uniform subsidence. However, the magnitude of the dynamic deformations may be sufficiently large to damage a structure in locations 1 and 2 before it reaches location 3. Therefore it is very important to study the characteristics of the dynamic subsidence basin. Under normal conditions, when the face has advanced for a distance approximately one-sixth to one-third of the seam depth from the setup entry, depending on the seam depth and the physical properties of the overburden strata, the movement of the over- burden strata reaches the surface, whereupon the surface also be- gins to deform. Thereafter, the surface point where the movement initiates is always located at a fixed distance ahead of the face. The angle between the vertical line at the faceline and the line connecting the movement initiation point on the surface and the face- line is the angle of advance influence, w. The angle of advance influence can be used to determine the distance, [ 1], which is the influence zone ahead of the face. w is approximately 20O to 35 O for the northern Appalachian coalfield (Peng and Geng, 1984). The movement of each surface point is a relatively complicated process both in time and in space, because the relative position between the faceline and each surface point varies continuously, so that the direction and rate of movement for each surface point differ. In the following sections, the movements of each surface point on the major cross section are illustrated. 3.2 DYNAMIC SURFACE MOVEMENTS Dynamic surface movements include dynamic subsidence and displacement. The movement of each point on the subsidence basin is different as the face advances from 1 to 6 (Fig. 3.2). Surface points A and B, being far in front of the moving face, subside and displace toward the face (i.e., from A to A' and from B to B'). Point C, which is quite near but in front of the moving face, subsides continuously but displaces initially toward the face and then turns to pure subsidence ending up at C'. Point D, which is behind the face above the gob, subsides continuously, but displaces initially toward the face when it is in front of the face and reverses to follow the moving face when it is behind the face, with the amount of displacement toward the face being larger than that following the face. As a result the net displacement is toward the center of the gob (i.e., from point D to D'). The same statement is true for point E. For point F, the net displacement is zero, i.e it appears to have dropped down vertically to F'. For points G to I, the net displacements are in the direction of face advance except the magnitudes are increasing in sequential order. Point 1, has reached the final dynamic position of 1'. In other words, the face has passed sufficiently away such that it does not affect the movement at point I. All other points (A to H) are still within the face influenced area. 3.3 DEVELOPMENT OF DYNAMIC SUBSIDENCE PROFILES When the face has moved for a distance of h/6-h/3 from the setup entry, surface subsidence reaches the surface. At this time the surface subsidence basin is very mild (S, in Fig. 3.3), and it is symmetrical about the center. As the face continues to advance, the maximum subsidence continues to increase, and its location moves with, but falls farther behind the face. When the face has advanced a sufficient distance, e.g., (0.9-2.2)h, away from the setup entry, the maximum subsidence reaches the maximum possible value (curve S,). At this time, the dynamic subsidence profile is fully developed. Thereafter both sides of the dynamic subsidence profile become stabilized. The subsidence profile on the face side moves with the advancing face in an orderly manner (curves S, and S,). When the face stops, the face side of the profile continues to subside and becomes stabilized (curves;) sometime after. Curve S; is the final subsidence profile (see Fig. 2.22). 3.4 DEVELOPMENT OF DYNAMIC DISPLACEMENT AND SLOPE PROFILES The dynamic displacement profile moves with the advancing face (Fig. 3.4), but changes according to some specific rules. When the face has advanced to A, the surface begins to move and its dynamic displacement profile has two maximum values (curve Ua): one positive near the setup entry moving toward the face advancing direction and the other negative on the face side also moving toward the face advancing direction. As the face continues to advance, the positive maximum displacement on the setup entry side increases and moves toward the face continuously. The same statement is true for the negative maximum displacement on the face side. When the opening increases to the critical size, both the maximum positive and negative displacements reach the peak values and remain constant thereafter. Notice that when the opening becomes critical in size, the point of zero displacement no longer moves with the advancing face. Rather it spreads into an area of zero displacement (curve Ue) and expands as the face advances. When the face stops, the displacement on the face side continues until it becomes stabilized (curve Úe). Curve Úe is the final displacement profile. The ratio of maximum dynamic to final displacement ranges from 60 to 75%. The dynamic slope profile follows the same patterns of change. The ratio of maximum dynamic to maximum final slope ranges from 50 to 80%. The maximum slope decreases with in- creasing rate of face advance (Peng and Geng, 1984). It must be pointed out that except for those near both sides of the profiles, each point on the displacement and slope profiles is subjected to a cycle of positive and negative displacements and slopes depending on its relative position with respect to the face.

Jan 1, 1992

By Lihong Zhou, DAVOOD BAHRAMI

A reliable and stable ventilation system is essential to the safe operation of underground mines. The stability of a mine ventilation system becomes extremely critical while responding to a fire incident since an unstable ventilation system will pose a risk of airflow reversal. The reversed airflow could bring the fire contaminants such as toxic gases and smoke unexpectedly to working areas. In the past few years, there has been a growing interest in the study of ventilation network stability using the concept of resistance sensitivity, which is described as an indicator of how the airflow in an airway is reacting to a resistance change of other airways. Several methods of calculating the resistance sensitivity in a mine ventilation network have been carried out by researchers and scholars around the world. However, the proposed methods heavily rely on a vast amount of mine ventilation simulations, which are very time consuming and computer-power intensive, especially for a large-scale mine ventilation network. In this paper, a derivative method calculating the resistance sensitivities with a single mine ventilation simulation has been developed and implemented into a mine fire simulation software, MFIRE. The results from the derivative method were verified against the results from a traditional method. The derivative method has been proven to be reliable and accurate.

Jun 7, 2022