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By Gregory M. Rumbaugh, Todd Kostecki, Christopher Mark

From 2015 to 2021, five massive pillar collapses occurred at four underground stone mines in the eastern United States. These events resulted in powerful airblasts that damaged mine infrastructure and mobile equipment, seriously injured miners, and disrupted underground travelways. Each of these pillar collapses propagated through the overlying strata, causing a subsidence basin on the surface. Pillar collapses are particularly hazardous for miners because they can occur with little warning and can affect miners that are far from the pillar collapse area. The following case studies show that certain factors may increase the likelihood of a pillar collapse. For instance, each of the five events involved the collapse of at least twelve benched pillars with width-to-height ratios (w/h) of 0.8 or less. This study elaborates on

By Gregory M. Rumbaugh, Todd R. Kostecki, Christopher Mark

From 2015 to 2021, five massive pillar collapses occurred at four underground stone mines in the eastern USA. These events resulted in powerful airblasts that damaged mine infrastructure and mobile equipment, seriously injured miners, and disrupted underground travelways. Each of these pillar collapses propagated through the overlying strata, causing a subsidence sinkhole on the surface. Pillar collapses are particularly hazardous for miners because they can occur with little warning and can affect miners that are far from the pillar collapse area. The following case studies show that certain factors may increase the likelihood of a pillar collapse. For instance, each of the 5 events involved at least 12 benched pillars with width-to-height ratios (w/h) of 0.8 or less. This study elaborates on these factors and proposes a framework to assist mine operators where they identify similar hazards.

Jul 24, 2023

By Angelo dos Reis Magalhães

Brazilian companies have adopted in recent years new management practices to remain competitive. Specialized consulting in asset management progressively creates or adapts new techniques in order to increase availability and reduce manufacturing costs, maximizing profits. New engineering concepts were acquired and implemented by executives in all business segments. Techniques, such as FMEA, RCM, LCC, Pas 55, Reliability studies by Monte Carlo simulations, among others, have become increasingly recognized as important tools to enhance managerial performance. Besides these techniques, this study suggests the importance of adequate structuring of a lubrication program, as a critical success factor for the reliability of any asset. Through a case study developed with a company in the mining sector, this work proposes the development of a master plan for lubrication based on three pillars: People, Equipment and Management system. Practices and care with lubricants, hydraulic fluids and coolant, until its point of application, shall be evaluated to ensure a correct contamination control and a high level of assets availability. This discussion sheds light onto other benefits of this process, including occupational health and safety; ergonomics; environment and sustainability.

Jul 31, 2018

By Jürgen Schanderl

Cold rolling mills by SMS Siemag are well known for their reliability and long-life cycle. They are an investment in the future. Nowadays mill owners are under considerable competitive pressure and are asked to organize production in a more and more efficient and flexible way. Doing so, a number of elevating screws have to be turned. These are: cutting of operation costs, especially by more efficient equipment and processes as well as transition to more process flexibility to fulfil future product requirements. To support owners in their effort, SMS Siemag offers convincing solutions in cold rolling technology under the brand X-Roll 2.0. Examples to be presented are: Sieflex®-HT drive technology; Redesigned DS system; New reel design: Twin Reel; Emulsion compact unit ECU Compact; TRC® threading assistance system; ECOMode and Energy ADVISOR monitoring system.

Jul 30, 2018

By K. Turgeon, D. Larivière, L. Whitty-Léveillé, J. -F. Boulanger, C. Bazin

"The processing of ore containing rare earth elements leads to the production of an impure solution of these elements. The separation of the rare earths from the impurities and the production of individual elements is usually carried out by solvent extraction. The effectiveness of the extraction conditions and of the reagents is generally tested in the laboratory. This paper deals with the processing of results from solvent extraction laboratory tests planned to generate data redundancy. A method is proposed to take advantage of the data redundancy by accounting for the pH variation during the extraction. The parallel processing of several tests also allows estimating the equilibrium constants for the extraction. The proposed method produces equilibrium constants that are more reproducible than values estimated using conventional approaches. The method is illustrated with solvent extraction tests conducted on synthetic solutions of rare earth elements.INTRODUCTIONThe processing of ores containing rare earth elements (REE) usually includes the production of a concentrate of the minerals carrying the REE. These minerals, for instance monazite and bastnäsite, contain the 14 elements from La to Lu plus yttrium and scandium. As an example monazite has the general formula of (La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy…Lu)PO4 with a typical lanthanum content of 20-26%, cerium content of 40-50%, praseodymium of 4-6%, neodymium of 16 to 20%, and decreasing concentrations of heavier elements (Gupta & Krishnamurthy, 2005). During the processing of a REE mineral, it is generally not possible to isolate and separate a single REE from all the rest. The mineral molecules need to be broken (usually via a heat treatment followed by leaching with a base and/or an acid) to produce an aqueous solution of the REE of the ore. After purification of the solution, the REE can be precipitated as a bulk concentrate and sold to a refinery that separates the REE into particular groups of REE such as the light versus heavy REE or into individual elements such as lanthanum, neodymium, or europium oxides to yield value-added products."

Jan 1, 2016

By A. M. Venter, C. W. Siyasiya, N. K. K. Arthur, M. G. Willemse, D. Marais

Although additive manufacturing is fast gaining traction in the industrial world as a reputable manufacturing technique to complement traditional mechanical machining, it still has problems such as porosity and residual stresses in components that give rise to cracking, distortion, and delamination, which are important issues to resolve in structural load-bearing applications. This research project focused on the characterization of the evolution of residual stresses in Ti-6Al-4V extra-low interstitial (ELI) additive-manufactured test samples. Four square thin-walled tubular samples were deposited on the same baseplate, using the direct energy deposition laser printing process, to different build heights. The residual stresses were analysed in the as-printed condition by the neutron diffraction technique and correlated to qualitative predictions obtained using the ANSYS software suite. Good qualitative agreement between the stress measurements and predictions were observed. Both approaches revealed the existence of large tensile stresses along the laser track direction at the sections that were built last, i.e., centre of the top layers of the samples. This in addition leads to large tensile stresses at the outer edges (corners) which would have the effect of separating the samples from the baseplate should the stresses exceed the yield strength of the material. Such extreme conditions did not occur in this study, but the stresses did lead to significant distortion of the baseplate. In general, the microstructures and spatial elemental mapping revealed a strong correlation between the macro-segregation of elemental V and the distribution of the β-phase in the printed parts.

Feb 6, 2023

By C. Holmes, T. Holmes

Engineered-in material handling problems are responsible for significant unrealized value in mineral processing plants. At the root, is a lack of awareness and understanding of bulk material handling science and how important it is, especially in early design stages. Mineral processes add value to mined raw feedstock through physical and chemical transformations in unit operations, but only if the material can flow through them. Essentially, each unit operation receives a unique feedstock and produces a unique product to be collected, transported, and fed into the next unit operation. Such material-handling systems can only be expected to achieve design throughput if the system equipment is designed to the materials’ characteristics, over their full range of conditions. This requires quantification of flow properties to support the necessary customized equipment designs. Too often, assumptions or “library values” of a material’s properties are used as the basis for flow modelling and conceptual, and sometimes even detailed, design. This is especially true for hazardous materials like uranium ore, for which the additional precautions, costs, and time necessary for safe handling are often used to rationalize postponing or even bypassing testing. The surprises that often transpire in the wake of insufficient material handling consideration can have acute and costly effects. Fortunately, there is a better way.

Jan 1, 2020

By Robert B. Crookston

Oil from shale has been produced in foreign countries for more than a hundred years; however, except for short-lived, small operations, no commercial quantity of oil shale has yet been produced in the United States. Efforts to develop a viable oil shale process have been underway domestically for many years. At the present time, with the need for energy so urgently upon us, almost a dozen development ventures are underway or planned in Colorado and Utah. Of these several ventures, only Colony Development Operation has completed the development, testing and design of a ready-to-go 50,000 barrel per day com¬mercial project. Colony is a joint venture of the Atlantic Richfield Company, Ashland Oil Company, Shell Oil Company and The Oil Shale Corporation, more commonly known as TOSCO. TOSCO is the exclusive licensor of the TOSCO II retorting process and other oil shale technology, which includes mining, crushing and spent shale disposal techniques. This paper will deal, however, with only the materials handling aspects of the commercial oil shale operation. Oil shale handling for this infant industry is unique in that an understanding of the physical characteristics of the ore and the demands on material handling to the plant must he understood. Colony Development has completed ten years in the research and development of techniques and processes for mining, crushing and retorting raw oil shale and the disposal of spent or processed shale. A great deal has been learned about oil shale, in many cases confirming our intuitive analyses and the work of others, but more specifically we have brought it all together to a point where equipment performance and the specifications have been established and a design for the first commercial plant is now mature.

Jan 1, 1975

By H. R. Thompson

The Grant Town Power Plant is a nominal 80 MW (net) Waste Coal-Fired Electric Generating Plant which is located in northern West Virginia, approximately 15 miles southwest of Morgantown. The Steam Generator consists of two (2) Pyro-Power Circulating Fluidized-Bed Boilers (CFB), each rated at 400 000 lbs/hour @ 1,350 psig. Main Steam. The Turbine Generator is a single GEC Ahlstrom unit rated at 95 MW gross and 80 MW net. The Plant began commercial generation during April, 1993. The facility is owned by American Bituminous Power Partners, L.P. (AmBit), and operated by Mission Operations and Maintenance, Inc.

Jan 1, 1996

By Alex Grenoble, Alex Reeb, George Filz, Farzad Abedzadeh

"This paper summarizes available information on the characteristics and properties of deep-mixed soilcement produced by the wet method. The topics covered in this paper include: unit weight, unconfined compressive strength, strength variability for field mixed materials, influence of curing time, influence of consolidation pressure, Young’s modulus, differences in strength and stiffness between small and large samples, creep deformations, Poisson’s ratio, and tensile strength. In addition, this paper discusses the development of design considerations and recommended property values for a project that uses soilcement to protect an existing dam penstock from loads applied by an overlying stability berm. Some of the key recommendations for the deep-mixed soil-cement to be used in this project are that (1) a curved strength envelope that includes tensile strength can be used in the analysis, (2) the stress-strain and strength properties can be characterized using Duncan and Chang's (1970) hyperbolic model, and (3) a specification based on the median unconfined compressive strength value is appropriate.INTRODUCTIONFor many projects, including foundation and embankment support, deep mixing can be designed based on simplified procedures and following standardized guidelines (e.g., FHWA 2013). However for unusually complex or critical projects, it is often necessary to perform numerical analyses, and in order to perform these numerical analyses well, a thorough understanding of the material properties is needed.This paper summarizes information on the characteristics and properties of deep-mixed soil-cement produced by the wet method, and it discusses the development of design considerations and recommended property values for a specific project, herein referred to as the penstock project, that requires numerical analyses. For the penstock project, a horseshoe-shaped enclosure of soil-cement is being considered beside and above an existing dam penstock to protect it from loads applied by an overlying stability berm that will be constructed for seismic remediation. The concept is to use soilcement created by the deep mixing method along the sides of the penstock and to use compacted soilcement above the deep mixing to create the crown of the protective soil-cement zone around the penstock. For this application, the soil-cement stiffness, rather than its strength, is the controlling design parameter. To achieve the necessary soil-cement stiffness, the strength will be high enough that the factor-of-safety values against instability along potential failure surfaces passing through the soil-cement are high. Following conventional practice, the soil-cement acceptance criteria will be based on the unconfined compressive strength, and the specified strength will be selected to produce the desired modulus value."

Jan 1, 2015

By O. Moselhi

Material can be seen as the fuel needed to execute the project from inception to completion. Material installed provides good indicators of progress achieved onsite vis-a-vis project schedule performance. It correlates well with the role of the schedule performance index (SPI) of the earned value method (EVM). Material is recognized to have a significant impact on achieved progress for physical completion of project activities. This paper presents a study on the development of material status index (MSI) in support of the EVM. Unlike the SPI, the newly developed index account for the criticality of project activities. This is carried out considering the total float of each activity, percent float (i.e. the ratio of float to activity duration) and the total float of the path on which the activity is located. MSI, can independently and jointly with SPI provide root causes behind problems encountered during project execution. In turn MSI can reveal material related factors behind the performance detected by joint interpretation of the two indices. MSI serves to provide added value in alerting management to take corrective actions. While SPI and MSI may have different values, they can jointly augment and enrich the captured project status based on EVM. To demonstrate the capabilities of the developed MSI method, it is implemented on a case study. The case encompasses the construction schedule of a hydro power station constructed in northern Quebec. Different scenarios are adapted from the real case to demonstrate a set of practical aspects of the developed index. The results generated from the analysis of the case study illustrate the useful features of MSI beyond those of the traditional SPI on two fronts; causation and the considerations of criticalities of actives.

Aug 1, 2013

Despite modest improvements in the performance of domestic interest rates and gross national product,1 fixed investment in domestic producers' durable equipment continued to weaken during the second quarter of 1982 and declined at a 12.8 percent annual rate compared with the first quarter.2 Large declines occurred during the second quarter in expenditures on many of the major mineral-consuming industries such as aircraft, computers, agricultural and construction machinery and mining and oil field equipment. These data appear to be consistent with the low level of business investment plans for 1982 reported in the DOC's Bureau of Economic Analysis survey of expenditures on new plant and equipment.3 Domestic and foreign industrial production and mineral industry production activities continued to decline in the most recent period because of weak demand conditions (Tables 1 and 2). The U.S. mining production index declined 7.7 percent between April and June as compared with 1.2 percent for total U.S. industrial production (Table 1).

Jan 1, 1982

By David J. Dunn

Materials related problems at mines can be big ones - like a newly completed 1 -m (3.5ft) water pipeline burst during initial filling, grinding ball consumption at double the typical norms on startup of a new semiautogenous grinding (SAG) mill circuit or 30 open-pit haul trucks in the shop for new bed liners after less than a year’s service. Materials engineering provides solutions to these kinds of equipment problems by selecting good materials and designs, by trouble-shooting service failures and by maintaining high quality in vendor-furnished materials and components. Materials with good properties, correctly made and fabricated, correctly installed in mining and processing equipment, produce ore and final products reliably and efficiently. Materials engineering, applied during design phases, specification writing, and receipt and installation of materials, ensures that equipment will have the best possible shot at performing up to expectations. Good calls on materials properties - specifying state-of-art materials produced by competent manufacturers - help mine managers to reduce downtime and mining and processing costs. Materials that are improperly made or specified can make a mining operation less efficient or, possibly, uneconomical.

Jan 1, 1992

By Ree Llewellyn

"It has been estimated conservatively that the costs of wear damage and friction in the Canadian mining and mineral processing industry amount to over one billion dollars per year. These are mainly incurred through the repair or replacement of worn parts and production losses from related equipment downtime. The selection and application of the most appropriate wear protection components and systems, can thus have a very significant influence on productivity, profitability and global competitiveness.Details are presented of the wide diversity of materials used to counteract the varied and often complex wear attack mechanisms that occur in surface mining. The majority are various forms of steels and irons with generally very high hardness. However, they also include relatively soft elastomers and polymeric products.The main characteristics and applications of the different classes are reviewed. Case studies record significant performance improvements achieved through more judicious selections. Finally, some new developments which reduce maintenance charges by substantially increasing wear component life, are described."

Jan 1, 1996

By Andrukaitis. E.

The increasing use of electronic equipment by the Canadian Forces has increased the importance of electric power. A power source that is packed with energy and yet light, small and durable is the common request of military users. However, this needs to be achieved while also addressing the requirements of safety, reliability and low temperature performance. The potential use of fuel cells in a military environment has become a possibility in several areas in the 21st century. Some examples of power source requirements and the materials related R&D required to give better, higher energy power systems in the future will be discussed.

Jan 1, 2005

Depressed prices for minerals will force the mining industry to became more efficient. The continuous conveying of pit product is one area in which savings can be made. Conveyors are available, or can be adapted to provide the flexibility and reliability required. Each conveying system will need to be custom designed to suit the particular requirements of the mine. The Australian mining industry must take the initiative and accept the challenge of the new technology.

Jan 1, 1986

By E. C. W. Perryman

Materials research and development has played an important role in the commercial success of the CANDU- PHW nuclear reactor and in the production of heavy water. Both capital investment and energy conservation demand very high component reliability in such systems. The interactions among reliability, plant performance and economics will be discussed in relation to materials research and development. Likely materials requirements for the nuclear industry over the next twenty five years will also be discussed.

Jan 1, 1977

By Zhao Guangwen, Wu Tan, Qiuzhan Tian, Duan Shuzhen

"A thorough study of lost currents in bipolar cells has been made for the development of the great potential of bipolar cells in energy saving. A proper equivalent circuit for bipolar cells has been found, and mathematic methods for computing lost currents at all kinds of polarization have been developed.At linear polarization, the lost currents can be computed by solving either a tridiagonal matrix or an ordinary differential equation of second order. This kind of values can be used to evaluate the minimal lost currents at given conditions. At other kinds of polarization, the lost currents can be computed by the same methods as above if the necessary experiments of measuring the cell voltages of every electrolytic compartment have been made. This kind of values can be used to design bipolar cells at practical conditions.Extensive experiments have been made to evaluate the effects of electrode polarization, emf of galvanic cell for the formation of electrolyzed substance, gaseous products, geometric dimensions of electrolytic cells, special resistance of electrolyte used, and the total and ordinal number of electrolytic compartments on lost currents. It is the first time to make such a systematic research by experiments in the world. Experiments showed that theoretic models were in good agreement with measured data. Experiments also showed that D.C. energy consumption of 0.45 kwh/kg of Pb for lead electrolysis from molten chlorides could be achieved in a cell with 7 bipolar electrodes.IntroductionIt is very promising to apply bipolar electrolytic cells to electrolysis of aluminum, magnesium, lead, zinc and perchlorinates for their great potential of energy saving for example, bipolar cells had been used in the production of magnesium and saved more than 30% of energy, being one of the three main techniques of energy saving in the production of titanium sponge (1)."

Jan 1, 1988

By J. W. Evans

Mathematical modeling has now become a standard technique in the development of new technology and the improvement of existing technology in the processing industries. Physical modeling has a longer history but a smaller following at present. The paper reviews some examples of the application of both types of modeling in non-ferrous metal extraction, particularly within the copper and aluminum industries. The objective is to show that well founded models can lead to results that have practical consequence in scaleup, design and operation.

Jan 1, 1993

By Y Li, D J. Williams, E Topal

A mine waste rock dump does not have any intrinsic value, yet is an inevitable structure in surface mining operations. Since the purpose of mining is to maximise profit, possible expenditure reduction in hauling waste rock to the dump, which can represent up to 50 per cent of the total operating cost, is highly desirable. Apart from cost, potential acid mine drainage (AMD), due to seepage from surface waste rock dumps containing reactive waste rock, could threaten the ecological balance, drinking water supplies and irrigation systems downstream from a mine site. In order to minimise these potential risks, selective placement of benign and reactive waste rock, and the encapsulation of reactive waste rock by benign waste rock, need to be carried out during the construction of the rock dump.In this paper, a new methodology, based on mixed integer programming (MIP) is developed to manage waste rock dumping. The model aims to minimise waste rock haulage costs by locating the optimum destination(s) for each waste rock block, while at the same time controlling the placement of reactive waste rock to minimise the potential for AMD. Tests on small-scale virtual data demonstrated that the model is capable of dealing with selective placement of different waste rock types, encapsulating reactive, potentially acid forming (PAF) waste rock, and stockpiling benign waste rock for encapsulation and rehabilitation purposes. The solution time for the MIP model is far less than the traditional manual approach, and the resulting schedule is up to 46 per cent more cost effective.CITATION:Li, Y, Topal, E and Williams, D J, 2012. Mathematical approach for better mine waste rock dumping management, in Proceedings Life-of-Mine 2012 , pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012