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By M. K. Larson, J. K. Whyatt

Proper employment of numerical stress analysis design tools is based on the demonstrated ability of a model to capture key elements of the geologic site model and accurately simulate how these elements interact with a mine design. While these tools have progressed markedly, they are, at heart, a gross simplification of the abundant complexity of a natural setting and its response to mining. A generic deep longwall site model was developed that includes aspects of the geology of deep coal mines in the Wasatch Plateau and Book Cliffs coal fields of Utah. The site model contains a set of common features and observations of how these features typically respond to mining. This site model was the basis for evaluating use of empirical, boundary element and volume element stress analysis tools to analyze the distribution of stress around a deep longwall panel. More specifically, this evaluation examined shifting of stress to panel abutments and gob, distribution of stress in the abutment and deformation and failure of bridging strata. Measurements of abutment stress changes at two sites in the Wasatch Plateau region were used to illustrate model calibration. Overall, these comparisons highlight the considerable differences between methods. Volume element tools can incorporate considerable detail and have fewer underlying assumptions, but this detail carries a considerable computational cost. Boundary element tools are much more efficient. However, this efficiency comes at the cost of added assumptions. These assumptions were challenged by the presence of a strong sandstone unit in the overburden, leading to boundary element results that depart significantly from volume element results. Empirical rules are the simplest, but are even more burdened by assumptions, many of which are implicit in underlying cases. Insight into the nature and impact of underlying assumptions in each method is essential to the proper use of results in mine design.

Jan 1, 2009

By Robert W. Gordon

The art of excavating tunnels with continuous, full-face boring machines began almost 90 years ago, in the early 1880's. At this time, Colonel Beaumont designed and manufactured a seven-foot diameter tunneler for boring under the English Channel, Despite the absence of modern materials and manufacturing techniques, Beaumont's tunneler, powered by compressed air piped in from the surface, was quite successful. During its short, but impressive existence, this machine set a record of advancing in chalk 50 feet per day for 53 days - which is impressive even by today's standards. Despite the apparent success of this early tunneler, almost 80 years passed before any further significant development was accomplished in this field. Demands from the construction and mining industry and society itself have motivated the development of the modern tunneling machine. Our rapidly growing civilization needs faster, less expensive and safer means of excavating tunnels. Space age technology and materials have played a major role in making hardrock tunneling machines possible.

Jan 1, 1970

By Steve Stuart

Deep-sea mineral SMS deposits present some of the world’s most challenging conditions for drilling equipment. As robotic seabed drilling services mature so too the ways that clients engage with service providers to maximise their data requirements. This presentation reviews key considerations for planning and executing a successful seabeddrilling program in variable mineralised deposits. Some of the means of collaboration between robotic seabed drilling contractors and those hiring their services are explored; where improved efficiencies and recoveries over the period of a drilling programme could be achieved. Potentially new technology or methodology can be looked at to further improve these approaches.

Sep 1, 2014

By A Deakin

It has been almost a decade since the release of the International Council of Mining and Metals (ICMM) Health and Safety Critical Control Management: Good Practice Guide (2015a). During this time the ICMM member companies, along with many others across industry, have been busy designing, deploying and enhancing their own critical control management (CCM) programs. So, what have we learnt? This paper discusses the scope, application and learnings from the implementation of CCM within the mining industry. What’s going well? What are the common challenges? What are the opportunities to strengthen the approach? What are the threats to successful implementation? The paper draws on the author’s experience as one of the key contributors to the development of the CCM Good Practice Guide and an adviser to many mining companies, including six of the ICMM members. The paper focuses on the practical (operational) application of CCM and the cycle of identifying, defining, implementing, verifying and improving critical controls at the frontline. The paper also includes a discussion on the safety performance of the ICMM member companies over the past decade and provides a recommendation for how CCM can be incorporated into a more proactive model to measure safety performance. The paper concludes with practical recommendations that mining companies, regardless of their CCM maturity, can consider as they look ahead. They are supplemented by three additional recommendations for consideration at the industry level.

Apr 16, 2024

By Dale Preece, Stephen Chung, Qian Liu

Stoping is one of the widely adapted methods in underground mining. In this method, fanned or parallel holes are often drilled from a top sill down to a sub- level in the ore zone and blasted ring by ring into a stope for excavation. At Brunswick Mine of Canada, this technique has been used daily in conducting production blasts. However, when mining into the West Ore Zone, it has been identified strategically that a mass stope blast, involving the blasting of rock from the 3-sub level down to the 1-sub level, should be considered to ensure the safe operation and regaining of access to the trapped main ore zone. The challenge of this mass blast lies in the control of ground vibration and precise timing for blasting 800 holes drilled in six blocks from three different levels within 6.5 seconds, to allow sufficient void to be created in each level for the muck moving in order from the upper to the lower levels without bridging. This paper describes stope blast simulations using a discrete element computer code for modeling blast-induced rock displacement in conjunction with a precision electronic programmable delay timing system for various stope geometries including a drop raise blast at the start of the mass blast. The modeling concept is also described in the paper.

Jan 1, 2003

By Sanket Rawat, Ravi Kant Mittal, Vikash Prasad

"The understanding of the response of pile foundations under various types of loads is a necessary prerequisite to analyze and design them properly. Therefore, this paper highlights and compares the provisions available in Indian Standard IS 2911:2010 to estimate the capacity of laterally loaded pile foundation with the provisions available in different country codes and existing literature. Comparisons are made between the Indian standard method, Broms method and Matlock & Reese method for the analysis of laterally loaded piles due to popularity and prevalence of the later methods in design offices worldwide. This has been achieved using a parametric study on pile embedded in pre-consolidated clay and sand for both fixed head and free head case in terms of displacement and ultimate load capacity. It has been found that there are various limitations to the Indian Standard method associated with various cases such as short pile analysis, complete moment distribution etc. Therefore, suitable recommendations have been made on the basis of the above comparison to improve the accuracy of the design in Indian perspective. The proposed comparison and subsequent area of improvements will present the design engineers all across the globe, a broad sight of design specifications of laterally loaded piles.INTRODUCTIONPiles in groups are very often subjected to both axial and lateral loads. In the 1960’s, designers used to assume that the piles could carry only axial loads and the lateral load is to be carried by batter piles. However, later, a large number of load tests authenticated that vertical piles also can transfer lateral loads through shear, bending, and lateral soil resistance rather than purely acting as axially loaded members. Initial attempts to analyze laterally loaded piles used the finite-difference method, as described by Howe (1955), Matlock and Reese (1960), and Bowles (1968). Matlock and Reese (1956) used the finite difference method to get a series of non-dimensional curves to enable the user to input the appropriate curve with the given lateral load and estimate the ground-line deflection and maximum bending moment in the pile shaft. Later, Matlock and Reese (1960) extended the earlier curves to include selected variations of soil modulus with depth."

Jan 1, 2017

By S. G. Malghan, V. K. Pujari

Detailed characterization of all the powder constituents during powder processing is necessary for the reproducible manufacture of ceramic components that will perform reliably in intended applications. In this paper, selected physical and surface chemical techniques for characterization of silicon nitride powder are evaluated. The characterization data are discussed in the context of how these data, through their influence on powder processing unit operations, can affect the final microstructure. In the forming of ceramics, some of the major variables of injection molding are evaluated. Accurate measurement and control of these variables is emphasized for manufacture of Si3N4 ceramics with a high degree of reliability.

Jan 1, 1990

By C. S. Chenga

Sustainable development is currently an extremely relevant concept worldwide, especially in developing countries like South Africa. Mining and metals companies are also directly affected by the sustainable development agenda. The Mining Charter?s requirements as well as new legislation (Mineral and Petroleum Resources Development Act) expect, among others, for mines to support infrastructure and poverty eradication projects in the communities surrounding the mines. The aim of this paper is to, against the background of a qualitative study of mining communities in the North-West Province of South Africa, put forward some critical factors for the sustainability of social development projects in the mining sector.

Jan 1, 2006

By Wenbing Guo, Gaobo Zhao, Erhu Bai, Brijes Mishra

"Violent damage to overlying strata can occur above the large mined-out space left by high-intensity longwall mining. For the safe mining under the aquifer and surface water body, it is imperative to investigate the criteria of overburden failure degree due to high-intensity mining. In this paper we present the characteristics of high-intensity longwall mining panels and overburden critical failure. Based on the geological and mining conditions of a high-intensity mining panel, 3D numerical models that consider the maximum horizontal principal stress and minimum horizontal stress and their orientations with the panel advance direction were established by using the 3DEC software. Sizes of the panel reaching the critical failure of the overburden under different mining thicknesses (3.5 m, 6.5 m, 9.5 m, 12.5 m, and 15.5 m) were analyzed. Further, criteria of overburden critical failure were proposed for the high-intensity mining. The coefficient of overburden critical failure (Cf) is the ratio of the strike length (Ls) to the mining depth (H). Through curve fitting analysis, a fitting equation between Cf and mining thickness was obtained. The results showed that overburden failure criterion with high-intensity mining panel is 0.38 = Cf = 0.97 with different thicknesses. Field measurements validated the results from the numerical models.INTRODUCTIONHigh-intensity longwall mining refers to a coal mining method with thick coal seam, large panel width, fast face advance rate, and severe damage to the overburden and surface in China (Guo et al., 2018). Violent movement of the roof rock and severe damage to overlying rock strata occur in the large mined-out space left by a high-intensity longwall mining panel, which is a 3D (three-dimensional) structure layout with highly non-uniform stress distribution. Recognition of such fact a will facilitate this overlying rock strata failure problem investigation (Peng et al., 2019).The studies of overlying strata failure due to longwall coal mining have been reported by some scholars with different methods. Kang et al. (2018) studied the sudden massive roof collapse during longwall coal retreat mining by a large-scale two-dimensional physical model and a UDEC numerical model. Ghabraie et al. (2015) researched the mining-related strata movement by applying the three-dimensional laser scanner, optical transducer, and digital image processing techniques to two-dimensional physical models. Wang et al. (2015) analyzed the structural characteristics and fracture failure process of overlying hard and thick main roof by a 3DEC numerical model; this study also investigated the geostress reduction and permeability enhancement redistribution of the adjacent coal measure strata by FLAC3D. Guo et al. (2012) performed a three-dimensional finite element analysis and shared some insights into the dynamic interaction between mining induced strata stress changes, failures, and gas flow patterns. Meng, Shi, and Li (2016) proposed a 3D coupling model between stress and permeability, investigating the dynamics of a stress, permeability coefficient using FLAC3D. Khanal, Guo, and Adhikary (2019) used the 3D numerical modelling approach (COSFOW) to investigate the strata deformation and the change in permeability in the overburden strata due to the underground extraction. However, few studies considered the influence of the horizontal stress on overburden failure in a high-intensity longwall mining panel, and the critical failure criteria of overlying rock strata is unclear."

Jan 1, 2019

By T. Liu, C. Shi, T. Fu, M. Zhong

Water inrush in coal mines is induced by the imbalance of the groundwater flow field and the engineering geo-mechanics field. Therefore, to prevent water inrush it is important to predict the critical hydraulic pressure of water inrush in coal seam floors. This paper will investigate a method for conducting theoretical forecasting of the critical hydraulic pressure of water inrush in coal seam floors by adopting the combination method of a genetic algorithm-neural network. First, the topology structure of a neural network (NN) based on genetic algorithms (GA) will be determined and then the critical pressure of water inrush in a coal seam floor using the chosen NN will be predicted. Finally, theoretical forecasting results will be compared with actual measurement results to determine the feasibility and applicability of this method.

Jan 1, 2008

By L. Mpolokeng, J. P. Labuschagne, H. Yilmaz

"An investigation into pillar cutting was carried out at a platinum mine on the western limb of the Bushveld Complex. The focus was on crush pillar design and implementation in order to ultimately improve the compliance percentage for pillar cutting. The major findings from the investigation suggest that the pillar cutting problem lies with the implementation of the design rather than the design itself. Observations of the practical issues underground that prevent good pillar cutting were made. After these issues had been identified, recommendations to rectify these problems and a few other issues identified during the investigation were provided. The recommendations are aimed at improving the pillar cutting compliance and reducing the likelihood of pillar bursts or pillar runs, which will ultimately create a safer mining environment. Paper written on project work carried out in partial fulfilment of BSc. Eng. (Mining Engineering)"

Jan 1, 2015

By James M. Griffin

Ladies and Gentlemen, There have been no less than ten major coal project financings in the last eighteen months. Each of these has been in the order of $100 million to $1 billion for the development of a coal property and its associated infrastructure. It is appropriate at this time to review the nature of these past financings. Why has there been so much activity? There are primarily two reasons. The first is due to the large number of contracts which were signed as a result of OPEC oil shocks. High projections were made for increased coal consumption particularly in world trade. This is distinct from domestic coal mine/power plant projects which often tap a government source of funds. Second is the high cost of coal development in the 1980's compared with a typical company's corporate borrowing capacity.

Jan 1, 1984

By J. R. Rau

While refuge chambers are common place in most underground mining projects, there are different philosophies as to what life support systems are to be considered and how these systems are to be applied. Case studies in the underground mining industry have examples of emergencies where the external compressed air and power supply to the refuge chamber were compromised due to proximity of services to the fire location. In 2005, The Department of Industry and Resources, Western Australia, drafted guidelines that listed specific requirements for refuge chambers which included a secondary life support system that would operate independently of external sources. The objective of this document is to examine what critical life support systems are essential for safe entrapment in the event of an emergency and to examine considerations for their application.

Aug 1, 2013

By J. R. Goode

Up to one half of neodymium and praseodymium production, key ingredients in permanent magnets, is produced illegally. About 60% of cobalt production, critical in lithium-ion batteries and other applications, comes from central African states, and much of it is produced illegally. Tantalum, important in modern electronics, is also primarily sourced from central Africa and, again, much of it illegally. Illegal mineral production, as exemplified here, is often used to fund armed conflict. Furthermore, it is typically conducted with scant regard for human rights and environmental protection. It also leads to depressed prices which in turn limits the possibility of legitimate producers entering the market. Systems of traceability and provenance, along with cooperative supply chain participants can limit the production of illegitimate material and thereby improve conditions in the countries of origin and reduce downward pressure on prices.

By James R. Hein

Manganese nodules from the Cook Islands (CI) Exclusive Economic Zone (EEZ) are compositionally different from other nodule fields. CI nodules have relatively high cobalt concentrations and low nickel, copper, and manganese concentrations (e.g. Hein and Petersen, 2013). This reflects the predominantly hydrogenetic (seawater source) origin for metals in the CI nodules versus dual seawater-pore water sources for most other nodules. The concentrations of many critical and strategic metals have not been previously analyzed for CI nodules, so comparisons with other nodule fields have been limited. To address this, we analyzed a set of nodules distributed throughout the CI EEZ for a complete set of 67 elements, including all of the metals that may be of economic interest, such as the rare earth elements (REEs), yttrium, tellurium, niobium, zirconium, tungsten, titanium, and others (see selected elements in Table 1). In addition, we recalculated the tonnages of nodules and contained metals from nodule abundance areas (in square kilometers) determined by GIS ArcMap calculations based on JICA/MMAJ (2001) nodule distributions. The nodule tonnage calculated and summed from each abundance sector yields a total inferred resource estimate of 9.66 billion tonnes of nodules covering an area of 1.21 million square kilometers; using a cut-off of 6 kilograms of nodules per square meter, yields a median tonnage of 8.59 billion tonnes of nodules covering 687,647 square kilometers (Table 2).

Sep 14, 2011

By William Gleason

The evolution of technology has made the world a more connected place. It continues to change the way we power our homes and vehicles and is leading to a future that seems to be limitless. Limitless as long as we can continue to supply the minerals necessary for technology to produce better iPhones, more efficient electric cars, better wind turbines and sophisticated national defense systems. These minerals, dubbed critical minerals, have surged in importance in every corner of the world and, on Aug. 3-4, they were topic of conversation at the Critical Minerals 2014 conference in Denver, CO. The conference, hosted by SME and the Australasian Institute of Mining and Metallurgy (AusIMM), looked at critical minerals from every angle, from where they are found to what the future might be. Among the minerals that have been called critical are rare earths, a collection of 17 minerals that have become increasingly important as technology continues to advance in everything from communications to energy to national defense. Leading off the conference, David Abraham, senior fellow at the Institute for Analysis of Global Security, explained that, like many people, he is relatively new to rare earths. Unlike most people, though, Abraham developed more than a passing interest in the minerals and has since travelled the world to understand the role of rare earths ? where they are found, how they are mined, how they get to market and, eventually, what applications they are used in. Following his travels, he said he returned concerned about the sector and how the industry will keep up with the demand that only seems to be growing in the modern world. And, Abraham noted, that it is not just the developed world that is driving demand. It stretches even to places like Indonesia, where the average annual income is about $3,000/year. Yet, the nation is one of the most active places in the world for social media with a population that is wired in with all kinds of electronics. The problem facing the sector is, and has been for a long time, and especially since 2010, supply of the minerals. At one time, China produced about 98 percent of the world?s supply and controlled the sector completely. In 2010, as the world began to demand more rare earths and develop other sources, China announced an export ban on rare earths. This changed the game completely, from the production lines all the way to the floor of the U.S. Congress.

By Zohreh Kazemi Motlagh, Virginia T. McLemore

There are more than 15,000 abandoned mine features in New Mexico. A considerable number of these mines have not been cataloged or assessed for prioritized reclamation efforts. These mine wastes can be examined as a resource of critical minerals. Many of legacy mine waste deposits have undiscovered commodities and critical minerals, due to low recovery processes during past production. In this project, Black Hawk mine wastes in Grant County, New Mexico are examined by thorough mineralogical and geochemical characterization. This project seeks to characterize and estimate the critical minerals in mine wastes of Black Hawk mine, and determine the acid generating potential of mine waste. Identifying and producing critical minerals in New Mexico may directly benefit the U.S economy and national security.

Feb 1, 2024

By E. J. Owen, A. Appah, I. C. Sanchez, K. T. Stafford, N. Hurtig, R. Otoo, N. A. Iverson, S. A. Moses, V. T. McLemore

New Mexico lies at the eastern edge of one of the world’s great metal-bearing provinces hosting numerous Laramide and Paleogene mineral deposits. Southwestern New Mexico contains Laramide porphyry Cu (±Mo, Au) and Paleogene Mo-W deposits. Porphyry deposits are generally large, low-grade deposits containing Cu, Fe, Mo, Au sulfides (and other metal sulfides) associated with porphyritic intrusions and exhibit characteristic alteration styles. Porphyry deposits can also be spatially and temporally associated with skarn deposits and polymetallic veins. All of these deposits have the potential to host various critical minerals, including Cu, Zn, Bi, Co, Ni, rare earth elements (REE), Te, and W. Critical minerals may be found as substitutions within ore minerals or as separate mineral phases. These deposits are constrained using 40Ar/39Ar dating into three ore-producing magmatic pulses: 1) ~78–71 Ma Laramide pulse, 2) ~59–50 Ma, Laramide pulse, and 3) ~40–30 Ma Paleogene pulse. New and historic whole-rock geochemical data have highlighted areas with critical minerals potential that require further study.

Feb 1, 2025

By K. T. Stafford, N. A. Iverson, V. T. McLemore

Laramide porphyry copper deposits are large, low grade (<0.8% Cu) deposits that contain disseminated copper minerals, breccias, and stockwork veinlets of copper and molybdenum sulfides associated with porphyritic intrusions in Southwestern New Mexico. Critical minerals, such as PGEs, tellurium, indium, germanium, and gallium are recovered from the anode slimes remaining after copper is refined. Detailed age dating, mineralogy, geochemistry, along with geologic mapping could refine the location of critical minerals within specific systems and could identify porphyry systems with elevated critical minerals that could become economic, in addition to the already produced copper, gold and molybdenum.

Feb 1, 2023

By B. Radwanek-Bak

The assurance of future raw materials supply to the EU mineral industry has become, in recent years, one of the most important tasks of the EU Commission. It is focused on creation a new mineral policy within the EU zone. One of the starting points for this activity was identification of the mineral commodities that are critical for the sustainable development and technological progress. The paper presents the glance to this problem from the National Member level. Domestic mineral reserve base as a possible source of critical raw materials for the EU was shown. Poland cannot be considered as its resource base. The source of these raw materials are not only scarce in Poland, but also they are not produced, and their demand is now - and according to forecasts is going to be in the future - met by imports. The raw materials in question are not considered exactly critical for Polish economy, but they are of limited economic importance. On the other hand, their growth is a best opportunity and at once the need to the future sustainable development.

Jan 1, 2011