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By SHANTAE LEE, ELAHEH TALEBI, Frank A. Drews, W. Pratt Rogers

Fatigue in mining operations is a serious issue and a significant contributor to incidents and accidents. While mine operators are using or introducing new technology to monitor operator fatigue, there is little work that focuses on the subjective experience of fatigue and the use of fatigue monitoring technology. To investigate this issue, eight focus groups with a total of 44 operators of heavy haulage equipment working for two mining companies in the Mountain West of the USA participated in 1-h focus groups. The topic of the focus groups was the experience of operator fatigue and issues surrounding fatigue at the workplace. The results of the content analyses suggest that operators are well aware of the signs of fatigue, and that they understand the severity of these signs as well. In addition, they are aware of the effect of fatigue on driving performance and are using a wide range of methods to manage fatigue. Finally, based on participants’ assessment, current fatigue monitoring systems lack face validity and reliability and are perceived as not being effective. The results of this study emphasize the importance of a socio-technical systems perspective in the context of miner health and safety management. Only such a comprehensive perspective can result in improvements that are sustainable.

Jun 17, 2020

By Holger Cordes

X-ray diffraction has long been used for qualitative and quantitative mineral analysis but Rietveld data analysis is still an under utilized method for mineral exploration and processing applications. In this full-profile approach the structural parameters of each mineral phase, together with experimental parameters, are refined by least-squares methods to minimize the difference between observed and calculated diffraction patterns. The result is a standard-less, quantitative analysis of the mineral abundance in the sample that is more accurate and considerably faster compared to traditional methods. The TOPAS software package combines a user-friendly interface with a unique approach to resolve overlapping peaks. Automated analysis options are also available and significantly reduce analysis time for routine samples. Several examples on a wide range of naturally occurring rock types are shown that illustrate the capabilities and limitations of the method. The examples include several options for the quantification of amorphous constituents like volcanic glasses.

Jan 1, 2006

By A. Rousselet, H. Gilbert-Tremblay, A. Berton

"Robex Resources interrupted production at the Nampala Mine in September 2014 following throughput and gold recovery results which were below expectations during the first months of operation. After a thorough plant audit, an important brainstorming took place in order to identify an economical path to resume production. It was clearly identified that a significant investment was necessary at the concentrator prior to restarting the plant, namely the addition of a ball mill and a new elution system.The mineral processing simulation software USIM PAC was used in order to simulate the grinding circuit in design. The simulations’ outputs allowed the ball mill characteristics and the surrounding classification devices to be designed with more accuracy. Many ball mills available from second hand retailers were therefore studied in the simulated circuit. The chosen ball mill, which was in perfect condition, had the advantage of being available for rapid delivery on site.The paper first describes the ball mill sizing method in comparison with the conventional Allis Chalmers method. It then describes the phase 2 concentrator start-up (that took place in 2016) with the commissioning of the ball mill, the classification circuit, the gravity concentration, the four (4) new carbon-in-leach (CIL) tanks, and the Zadra elution system (The phase 1 start-up took place in 2014). It finally provides production data compared to expected simulation data, as commercial production was reached in January 2017.IntroductionDesigning a new concentrator or new equipment within an existing concentrator requires significant efforts to identify possible bottlenecks and their causes (i.e. limiting equipment or sectors) and accurate sizing of major equipment can have a tremendous impact on the economy of the whole project. In the presented case study, the ball mill was the critical equipment and oversizing it could have brought the Capex to a level where the project would not have gone through. Inversely, undersizing the mill could have resulted in lower production and therefore no economic viability for the project once it is in operation.During engineering studies, equipment sizing often relies on a static mass balance and one-by-one sizing of all pieces of equipment. The sizing is then left to the equipment manufacturer or in the case of mills, evaluated with empirical models mostly relying on the Bond equations (Allis Chalmers method) [Rowland and Kjos, 1978]. This methodology shows the disadvantage of not considering interaction between equipment in a mineral processing circuit, especially when recirculation occurs. Also, it has the disadvantage of not using the more advanced grinding models that include the use of the whole particle size distribution as well as phenomenological components by only using limited parameters in the ore particle size distribution (i.e. the P80). This can be explained by the lack of data that sometimes needs to be gathered in order to tune the more advanced models but also by the conservative mindset in mineral concentration engineering which does not always favor the use of process simulation. In many aspects of process engineering, Soutex has demonstrated its affinity to using simulation in order to size equipment with more accuracy, consider process variability, simulate complex systems, and study supply chain management (Berton et al., 2015)."

Jan 1, 2018

By P. W. Jerant

The methane emissions from an advancing coal mine section were continuously monitored for 120 days. During this time, the section advanced 2,000 feet into virgin Pittsburgh coalbed producing 54,565 tons of coal with a total methane emission of 91 million ft3. Analysis of the data gathered showed that daily methane emissions did not correlate with overburden thickness and daily coal production. A good correlation was found between the daily methane emission and the average length of rib exposed to virgin coal.

Jan 1, 1976

By R. Barany

The heat of formation at 298.15 ° K of muscovite was determined by solution calorimetry . The value obtained for the heat of formation from the elements was -1,421.2 ± 1.3 kcal / mole , and the value for the heat of formation from the oxides was -55.9 ± 1.3 kcal /mole .

Jan 1, 1964

By Joseph P. Flick, Kathleen M. Kowalski, Lynn L. Rethi, Roberta A. Calhoun

Many miners are involved in tasks at the mine site that are similar to those sub-tasks performed in general construction, maintenance and repair (CMR) type work activities. As a result, many of the injuries in the mining industry today can be traced to employees performing these CMR type work activities. Indeed, a recent analysis of a major aggregate company revealed that 65% of all injuries documented originated from performing such CMR activities. It is hypothesized that the number of injuries to miners performing construction, maintenance and repair (CMR) work activities on mine property may be reduced through improved training that focuses on better hazard recognition using the numerous visual and other cues that are available for evaluating workplace health and safety hazards. To this end, researchers at NIOSH’s Pittsburgh Research Laboratory have merged two proven methods of training miners to recognize hazards, stereoscopic (3-D) slides and the concept of degraded images, into this training program. Stereoscopic (3-D) slides have been shown in earlier NIOSH and U.S. Bureau of Mines research to be an effective training aid for improving the ability of miners to recognize various geologic and mining-induced irregularities that can cause groundfalls.3 They realistically portray the natural mine environment, and thus are an excellent training aid for teaching miners to recognize such visual cues. The degraded image concept, originally developed by the military and used for target detection training, describes scenes where the target is partially hidden by cloud cover, dust, rain, natural barriers, buildings, or other obstructions that can camouflage or confuse the target. Research had shown that flight observers who were trained with less than ideal (or degraded) pictures were more successful in subsequent identification of targets than those trained using ideal (or highlighted) pictures of targets. In order to investigate this concept for training miners to recognize hazards, NIOSH researchers developed a prototype hazard recognition training program using such mining scenes. A control program based on traditional highlighted mining scenes was also developed. Both programs were applied to subjects in a field experiment. Results indicated that miners trained with the degraded images did significantly better on a follow-up test of hazard recognition.4 This hazard recognition program teaches trainees to look for hazards in a more realistic manner than that of the control program. This specific training program for CMR activities involves using the degraded image concept and 3-D slides. The module is designed to educate workers on hazard identification techniques and safe work practices. It focuses on teaching miners techniques for recognizing visual (sight) cues, and then uses these cues to evaluate mining conditions. It should be stressed that other senses, such as sound can also play an important role in hazard detection.

Jan 1, 1999

INTRODUCTION Trade financing is a particularly important component of short-term financing for a minerals company since errors, extra costs, or payment delays/defaults can easily wipe out the profit margin on a particular shipment or can cause problems when arranging purchases of e.g. reagents. It is required to make any minerals operation function and does not have to be cross-border to require proper management. Sources of working capital are as follows: 1. Extended credit terms from suppliers 2. Inventory loans from banks, finance companies 3. Accounts receivable financing or factoring 4. Credit lines or overdraft facilities from banks. TRADE CREDITS These are provided under the familiar terms "net 10 days" or payment due by the "10th day of the following month." Thirty days for payment is usual but longer periods can be negotiated with regular suppliers. Shipment may be made on open account with specified periods for settlement. In the mining industry, a custom smelter gains trade credit by paying for concentrates three months after the month of shipment. INVENTORY LOANS Various forms of inventory finance are provided via "floor-plan" or warehouse financing. A set percentage, usually 60%-80%, of a good-quality, readily saleable inventory item (e.g. bullion, concentrates, ingots) will be provided by a bank or finance company which will usually have security over these products and has a right to inspect the goods from time to time. Legal security will he achieved by warehouse receipts, floating liens, chattel mortgages, trust receipts, or through collateral management service companies. The latter certify control over stock or distribution outlets and often carry insurance against fraud. Costs range around 1.5% - 2.0% p.a. or more plus some fees to cover out-of-pockets or other costs. ACCOUNTS RECEIVABLES Accounts receivable financing is based on the company's generation of satisfactory receivables which are continuously assigned to a bank or finance company ("factoring"). Because of the risks in being able to collect receivables, such as payments to a smelter for its blister copper shipments to a refinery, this form of financing costs as much as 3% - 5% of the debt amount purchased plus an additional charge for processing paperwork. Receivables can be purchased with or without recourse and on a notification or non-notification basis to the client's customer to, respectively, pay the invoice directly to the bank or not. LETTERS OF CREDIT Letters of Credit ("L/C's") are a common feature of international trade finance whereby a bank, at the request of the buyer, issues a written undertaking to an exporter to pay a specified sum of money within a set time on presentation of previously specified documents. This undertaking means that the exporter is no longer relying on the credit standing and integrity of the foreign importer. A dispute about shipment does not otherwise affect the obligation to pay upon presentation of a "clean" set of documents. These documents include the hill of lading and other documentation, often on standard "form" bases. There are a number of conventions and techniques in L/C's such as irrevocable/revocable L/C's, time L/C's, confirmation/advising L/C's and transferable L/C's. These are tools to adjust for the varying risks that the importer will not pay. Other routes where one is comfortable with an importer include documentary sight hills (D/P hill), documentary term bills (D/A bill), and, of course, open account.

Jan 1, 1985

By Robert J. Anderso

Few elements have received more attention and developed greater interest in the last ten years than titanium. The substantially pure metal has been din...ie. cult to isolate, and so far has been little employed oommercially, but the use af alloys and chemical compounds of titanium has increased markedly in recent years. The earlier attempts at preparing pure titanium resulted in various impure forme which, from their metallic appearance, were always mistaken for the metal. Hunter in 1910 isolated pure titanium by the reduction of titanium tetrachloride with sodium. This brief statement is issued by the Bureau of Mines in response to numerous inquiries which have been received concerning titanium. More complete in. formation on the metal may be had by consulting the referenpes appended. The Literature is voluminous and only the more important references are Riven. It has been drawn upon freely in preparing this report; also information was supplied by M. g. Hunter, Arthur Braid, M 1. Schmid, C. M. Johnson, N. B. Hoffman, and de Courny Browne. The pioneer investigator in titanium is A. IL Rossi.

Oct 1, 1922

By C. Joulian, A. G. Guézennec, A. Chmielarz, Y. Ménard, M. Hanke, P. d’Hugues

"The copper concentrate used in this study is produced by flotation of a black shale organic rich ore. This resource is a carbonate-rich, polymineral concentrate. In the last 5-6 years, ore characteristics changed and the concentrate grades degraded. This study evaluated bioleaching of the concentrate in stirred tank reactors as an alternative to the pyrometallurgical technology that is currently applied, and which may no longer be feasible in future given the concentrate chemistry.The first part of the study focused on testing non-traditional operating conditions during continuous bioleaching experiments: high solids concentration (> 20% solids), reduced agitation and aeration rates. For the same residence time, bioleaching performance at high solids loading (25%) was the same as that reached during previous bioleaching experiments at 15% solids. No mixing or microbial issues were encountered. The bacterial consortium used in the experiments demonstrated a high copper tolerance.The second part of the study was devoted to technology development for metal recovery from copper bearing solutions obtained during bioleaching experiments. Due to the high copper concentration of the leachate, solvent extraction prior to electrowinning was not necessary. After iron removal, high quality copper cathodes (morphology and composition) were obtained from the PLS by electrowinning."

Jan 1, 2014

By Jason J. Ballentine

This case study presents the results of a maintenance review of a soot blower system at a coal fired power generation station. The power generation station was following a ?repair when it breaks? maintenance strategy for its soot blowers. The efficiency losses incurred as a result of failures in the soot blower system and the resulting interruption and out of service time was found to have a significant effect on the plant output. The maintenance strategy for the soot blowers was reviewed using Reliability Cantered Maintenance and lifecycle simulation. This methodology provided visibility to the monetary implications of failures and allowed alternative types of maintenance to be assessed and where justified were added to a maintenance schedule in the Maximo work order management system. By reducing unplanned breakdowns the predicted reduction in efficiency losses was 45%.

May 1, 2007

By M. G. Zabetakis

Benzene and toluene are the first two members of an important homologous series whose general formula is CnH2n-6. The members of this series differ in composition from benzene by some integral multiple of CH2; they can all be prepared in the laboratory by the Wurtz-Fittig, Friedel-Crafts and Grignard syntheses. Because 'of the industrial importance of these-hydrocarbons, the limits of flammability of eight members of the series have been determined at 100° C.-(A temperature of 1000 C. was chosen because the determination of the upper limit of flammability of p-cymene requires an apparatus temperature. of at least 90° C. As elevated temperature data are available for other combustibles at 100° C. but not at 90° C., all data were taken at 100° C. in order to obtain comparable results.) Minimum ignition temperatures of these combustibles have been determined at laboratory-pressures.

Jan 1, 1951

By R. A. Wyman

A comparison of the amount of minus-28-mesh product produced by a standard grinding test procedure is provided for 45 non-metallic materials. The percentage of product, the weight of product per unit of energy used and the weight of product per mill revolution are shown. The results exhibited excellent reproducibility and demonstrated an accurate comparison of grindability for non-metallic materials.

Jan 1, 1977

By Nasri Munfah, Steffen Matthei, Vojtech Gall

"Conventional tunneling as defined by ITA WG19 is also known as the New Austrian Tunneling Method (NATM) or Sequential Excavation Method (SEM) was transformed in the US to deal with challenging tunneling conditions as an alternative to the more traditional tunneling methods. It is being used more often in urban areas, under difficult ground and ground water conditions, and with limited cover. Often the tunnel is of a large and non-uniform cross section in soft soils or weak rocks. The intent of using this tunneling method is to minimize impact on traffic and utilities and reduce disruption of everyday life of people and businesses. To meet these challenges, the industry developed technical approaches and implementation techniques and established sophisticated contractual relationships and collaboration in the field among various parties for successful implementation. This paper examines the development of conventional tunneling (NATM/SEM) in the US to deal with these challenges using recent examples such as Russia Wharf in Boston, Northern Boulevard Crossing, in New York, and Chinatown Station in San Francisco. INTRODUCTION / HISTORY Conventional tunneling or NATM/SEM is a concept that is based on the understanding of the behavior of the ground as it reacts to the creation of an underground opening. In its classic form the SEM/NATM attempts to mobilize the self-supporting capability of the ground to an optimum thus achieving economy in ground support. Initially formulated for application in rock tunneling in the early 1960’s, NATM has found application in soft ground in urban tunneling in the late 60’s and has since then enjoyed a broad, international utilization in both rural and urban settings. In the US the NATM/SEM tunneling method has been used successfully to address challenging tunneling conditions in urban areas. A large number of tunnels have been built around the world using a construction approach which was loosely termed NATM. During the years of discussions and the application of NATM a variety of terms have been used for the same construction approach. These terms were primarily aimed at describing the construction approach rather than the region of its reported origin."

Jan 1, 2016

By J. E. Xu, J. Y. Zhang, M. Q. Sheng, K. Wan

"SynopsisThe densities of selected CaO-Al2O3-MgO slag systems were measured at 1823K by the Archimedean method. Thirteen different slag compositions were chosen based on different levels of the MgO content and the mass ratio of CaO/Al2O3. The results indicated that the density of the slag decreases with increasing MgO content (from 0–3.78 mass%), but increases with further increases in MgO content up to 11.33 mass%. At a fixed MgO content of 5.5%, the trend of density change with CaO/Al2O3 in the slag is similar to that for changes in MgO content. On the basis of the regular solution approximation rules of excess molar quantities, an attempt was made to estimate the molar volume of the slags investigated. The application of the molar volume model confirmed that the present expanded approximation rules are applicable to predict the molar volumes of the melts discussed.IntroductionDensity is one of the most important fundamental properties of slags, which influences metallurgicaly phenomena in many ways. Density is sensitive to the nature of the chemical bonds and the species in the melt, and is of great importance not only for theoretical research on the structural properties of molten slags, but also for industrial applications. Density is also required to estimate other key properties used to assess the behaviour of high-temperature molten oxides, e.g. viscosity, surface tension, and thermal conductivity.Liquid calcium aluminate slags that contain magnesia are the basis of most ladle slags for secondary refining processes. The CaO-Al2O3 binary phase diagram (Hallstedt , 1990) shows the eutectic composition (50 wt% CaO and wt% Al2O3) has the lowest melting temperature. The main emphasis of this study is on the 12CaO·7Al2O3 refining slag with MgO additions. The CaO-Al2O3-MgO ternary system is of considerable importance in industrial metallurgical processes, and is fundamental to the understanding of metallurgical slags, ceramic materials, and geological phenomena."

Jan 1, 2015

By D. R. Willmer, E. J. Haas

"DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health. ABSTRACT This study analyzed the publicly available health and safety policies of 26 mining companies to determine the quantity of health and safety (H&S) practices that mining companies encourage in relation to the Plan-Do-Check-Act cycle. A thematic content analysis of the policies identified elements and practices within the text. On average, companies communicated information on about 7 elements (range 1–14, standard deviation = 3.49) and discussed 15 practices (range 2–34, standard deviation = 9.13). The elements in which companies highlighted the most practices were risk management, emergency management, leadership development, and occupational health. A discussion of the policy trends shows areas that mine sites can improve upon within their Plan-Do-Check-Act cycle, in addition to encouraging the use of both leading and lagging indicators to manage health and safety performance. INTRODUCTION Mining companies and their employees are expected to identify and manage risks at their worksites to ensure the health and safety (H&S) of everyone at the site. The primary mechanism in place to control these risks is a company’s health and safety management system (HSMS) (Boyle, 2012). Broadly, an HSMS is a set of standard, interrelated, and interacting elements used to promote and achieve occupational H&S goals (ANSI/AIHA Z-10, 2012; BS OHSAS 18001, 2007). The practices conveyed within an HSMS are expected to minimize incidents, injuries, illnesses, and even save worker lives (Alsop and LeCouteur, 1999; Arocena and Núñez, 2010). In the United States, both the Occupational Safety and Health Administration (OSHA) and Mine Safety and Health Administration (MSHA) regulate and encourage aspects of an HSMS (US Federal Register, 2011, 2010). Many HSMS documents (i.e., Chemical Industries Association, 1995; Health and Safety Executive [HSE], 1995; International Labour Office [ILO], 2001) attribute the source of their basic management system to Deming’s Plan-Do-Check-Act (PDCA) model of continuous quality improvement and organize their practices within this cycle (Johnson, 2002). The PDCA cycle is a well-adopted approach in health and safety management and promotes continuous learning and adaptability (Robson et al., 2007)."

Jan 1, 2018

By D. Harrington

Fire is always a serious-menace, whether in a residential or in an industrial region; in wartime it is particularly damaging in an industrial plant. The mining industry is especially vulnerable, as its plants are generally more or less isolated front centers of population and do not have access to modern fire-fighting equipment; moreover, owing to the transitory rapture of most mines, their surface structures; are often relatively flimsy and flammable.. Trained firemen seldom are available at or near mining plants to teach the fundamentals of fire-fighting to local fire brigades, with the result that efficiency in combating actual fires is lacking. Often the attitude "it can't happen here" is held by the management of a mining property, unless the plant has suffered a serious fire; even then lapse of time is very likely to induce forgetfulness as to the possible hazards. The necessity for producing metals for the prosecution of this war has increased management's responsibility. Whereas heretofore the loss of a plant or mill by fire meant merely monetary less to the stockholder of the company, now the national interest is affected, in that the nation suffers from loss of production of minerals indispensable for war purposes.

Jan 1, 1943

By Lifeng Zhang

The transport of fluid, heat ,and particles (bubbles and solid inclusions) in flowing molten steel is investigated in steel refining ladles, the continuous casting tundish, continuous casting mold and strand, and steel ingot casting processes. The two-equation k-?? model is used to simulate the turbulence. Multiphase fluid flow is numerically simulated with a Lagrangian-Eulerian approach, an Eularian-Eulerian approach and the Volume Of Fluid (VOF) method. The simulation can predict inclusion trajectories, inclusion removal fraction, free surface waves and other phenomena, which can be used to optimize these important metallurgical operations.

Jan 1, 2006

By C. H. Stephenson, Z. White

This paper presents the design approach case study for incorporating a Technogrid® conveyance End-of-wind arresting system within the new South32 Hermosa headframe. Focus is placed on energy absorption requirements, structural integration, and mounting details tailored to the geometry and operational constraints of the headframe. Key considerations include arresting forces, load path continuity, and connection design to ensure reliability and maintainability. The paper also discusses coordination with other headframe systems and the iterative design process used to meet safety standards and client objectives.

Feb 22, 2026

By Wolfgang Baum

Case studies from epithermal gold-silver deposits in the western United States and in Latin America show that the routine use of process-related mineralogical studies has become an important tool for the reduction of development, capital and operating costs. Bypassing the mineralogical characteristics of epithermal gold-silver ores, as a result of fast-track development approaches, has resulted in multimillion dollar metal losses and/or in considerable modification costs of existing operations.

Jan 1, 1988

By David Hatem, Michael Vitale, Joseph Gildner, Michael Roach, Fred Dunham

Dispute Review/Resolution Boards (DRB’s) are a highly successful dispute avoidance and resolution tool. In a joint effort between the UCA of SME and the Dispute Resolution Board Foundation (DRBF), the authors embarked on an informal assessment of the state of the DRB practice in the tunnel industry from the point of view of the Contractor, Owner, DRB Practitioner, and Attorney. The results of this assessment were presented in a panel discussion at the Rapid Excavation and Tunneling Conference (RETC) in June of 2021. This paper presents the results of that session with recommendations for further industry discussion and implementation

Dec 1, 2022