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By K. A. Natarajan, S. Usha Padukone

"An industrial waste liquor having high sulfate concentrations was subjected to biological treatment using the sulfate-reducing bacteria (SRB) Desulfovibrio desulfuricans. Toxicity levels of different sulfate, cobalt and nickel concentrations toward growth of the SRB with respect to biological sulfate reduction kinetics was initially established. Optimum sulfate concentration to promote SRB growth amounted to 0.8 - 1 g/L. The strain of D. desulfuricans used in this study initially tolerated up to 4 -5 g/L of sulfate or 50 mg/L of cobalt and nickel, while its tolerance could be further enhanced through adaptation by serial subculturing in the presence of increasing concentrations of sulfate, cobalt and nickel. From the waste liquor, more than 70% of sulfate and 95% of cobalt and nickel could be precipitated as sulfides, using a preadapted strain of D. desulfuricans. Probable mechanisms involving biological sulfide precipitation and metal adsorption onto precipitates and bacterial cells are discussed.IntroductionIndustrial effluents from hydrometallurgical and mineral processing operations often contain high sulfate and metal concentrations posing significant disposal problems, which require urgent solution to avoid serious environmental contamination. In such waste liquors, sulfate and heavy metals such as cobalt, nickel, zinc and iron originate from the chemical or biological oxidation of exposed sulfide minerals. Reduction of sulfate and precipitation of toxic metal ions from industrial wastes is essential from the viewpoint of environmentally acceptable waste disposal and recovery of associated strategic metals.Many of these heavy metals are essential for metabolic activity of bacterial cells at low levels. But they exert toxic effects at concentrations encountered in polluted water. Removal of toxic metals through biological reduction of sulfates from industrial waste waters have been practiced for several decades. Metal remediation through common physicochemical techniques such as oxidation-reduction, chemical precipitation, filtration, electrochemical treatment, evaporation, ion exchange and reverse osmosis processes is expensive and not suitable in the case of voluminous effluents containing complexing organic matter and low metal concentrations. Further, strong and contaminating reagents are used for desorption, resulting in toxic sludge and secondary environmental pollution. Biotechnological approaches can be more efficient and cost effective for detoxification of such effluents. Biotreatment/ bioremoval offers several advantages over conventional chemical and physical treatment technologies, especially for diluted and mixed contaminants. Biological detoxification, which involves the use of microbes to detoxify and degrade environmental contaminants, has received increasing attention in recent years (Iwamoto and Nasu, 2001). In addition, valuable metals can be recovered from metal sulfide sludge (Boonstra et al., 1999)."

Jan 1, 2015

By J. Seo

We propose a dynamic biomechanical simulation method that uses motion capture to evaluate the risk of Work-related Musculoskeletal Disorders (WMSDs). Statistics show that WMSDs accounted for 33% of all non-fatal occupational injuries and illness in construction in 2009, and were a leading cause of temporary and permanent disability. Present methods rely largely on self-reports from workers, observational techniques, and direct measurements of motion and muscle activity to assess awkward postures, physical loads, repetitiveness, and the duration of exposure. While these methods have helped to prevent WMSDs in construction work, they may not be suitable for estimating the internal tissue loads associated with WMSDs. We propose a dynamic biomechanical simulation method to estimate internal forces and moments at each body joint of construction workers with motion capture data. Particularly, we explore the biomechanical loads by simulating active 3D musculoskeletal models based on measured postures and movements. To demonstrate the feasibility of this approach, we studied a ladder climbing task using a portable ladder under controlled laboratory conditions. Postures and motions were determined with a commercial motion capture system (e.g., VICON). The results were analyzed to investigate the feasibility of identifying risk factors based on biomechanical simulation. The results show that the proposed approach allows us to determine the biomechanical basis for WMSDs, and to identify postures and movements associated with excessive physical demands on each body joint. When combined with marker-less motion capture which is our ongoing work, the proposed approach has the potential to assess an individual?s motions and to provide personalized feedback for the purpose of reducing biomechanical loads and WMSD risk in real workplaces.

Aug 1, 2013

By B. A. Wilcox, A. H. Clauer

DURING the course of an investigation on the high-temperature creep behavior of TD Nickel* (Ni + 2) vol pct ThO2), it was observed that the creep fractures were similar in appearance to low-temperature ductile fibrous fractures and creep ruptures by cavitation. Microfractographs of fibrous ruptures are typically characterized by a dimpled appearance, with second-phase particles frequently found near the bottom of the dimples.'-4 These somewhat resemble creep ruptures by cavitation, in that fracture occurs by void formation, with the subsequent growth and final merging of the voids to form a complete fracture.' It is the purpose of this communication to describe the creep fracture of TD nickel and suggest a mechanism for the rupturing process. The discussion is relevant to material crept to fracture in vacuo at a constant stress of 18,000 psi, over the temperature range 900" to ll00°C. The material used in this investigation was 1/2-in.-diam bar stock supplied by Du Pont, contain- ing 2.3 vol pct Tho2. The final fabrication treatment consisted of -95 pct reduction by swaging followed by a 1-hr anneal at 1000°C. Transmission and replica electron microscopy revealed that the material had a fibered structure with a transverse grain size of -1 µ and a longitudinal grain size of 10 to 15 µ. Selected-area diffraction indicated that the fiber axis was parallel to (00l), in agreement with the results of Inman et a1.6 The thoria particle size varied from 80 to 1000Å, with an average size of 400Å, and the mean particle spacing was about 1200Å. The remarkable structural stability7 was confirmed by annealing for 6 hr at 1300°C (about ' 0.9 the absolute melting point). Transmission electron microscopy revealed that the only structural change was a slight decrease in dislocation density. Furthermore, recrystallization or grain growth during creep has not been observed. All specimens were annealed in vacuo at 1300°C for 3 hr prior to creep testing. The following times to rupture were obtained for vacuum creep tests at a constant stress of 18,000 psi: 900°C, 854 hr; 930°C,

Jan 1, 1965

By Robinson Newcomb

Gypsum is a form of hydrated calcium sulfate (CaS04.2H20) which is widely distributed over the earth's surface. The two varieties worked commercially are rock gypsum and incite. Rock gypsum, the variety commonly mined for commercial purposes, is a relatively soft mineral having a specific gravity of about 2.3 and weighing about 150 pounds per cubic foot. The chief producing States are New York, Michigan, and Iowa. Before being used the crude gypsum is ground and generally calcined. The predominant use of gypsum is for building purposes (the manufacture of plaster), for which calcined gypsum is required. Gypsum is also used as a retarder in Portland cement, as fertilizer, and for other purposes. GYPSUM MINING Crude gypsum is mined by two methods - underground and open-pit. Although the use of the former method predominates, open-pit mining increased in relative importance during the early twenties and contributed about two-fifths of the output during the period 1925-38.

Jan 1, 1940

By C. Doucet

Since 2001, CANMET Mining and Mineral Sciences Laboratories (MMSL) have worked with Falconbridge Ltd. (now Xstrata Nickel) to evaluate trends in the strength development and water retention properties of a novel backfill material for underground mining, called gelfill. Between 2004 and 2006, extensive laboratory tests were undertaken under the leadership of the Deep Mining Research Consortium (DMRC). This paper compares results obtained from samples circulated through a mini-flow loop and a simple mixer. Although many parameters were studied over the last five (5) years, this paper focuses on the investigation of the effect of the mixing method, sequence and time, and the curing environment on strength development and water retention of gelfill. It was found that binder should be added as a powder to the mix in the mini-flow loop, and that mixing slurry in the mini-flow loop as opposed to the mixer generally yielded higher strengths. The practical implications of these observations are the subject of an on-going underground trial that will compare laboratory and in situ properties of regular slurry fill with gelfill.

May 1, 2007

By Nick Hazen

Many successful actions are required to bring a profitable extractive metallurgical operation into production. Competent process development performed within the project development schedule increases the chances of obtaining project financing and decreases the risk of engineering design errors being built into the commercial plant. The general sequence of steps in process development is well known: technology review, desktop studies, scoping studies, prefeasibility, and so on, with an increasing requirement for experimental evidence as the studies advance. This paper suggests principles for guiding process development work so that the efforts stay on track toward a smooth startup and a profitable commercial operation. It emphasizes closely aligning the research with the corporate goals of the mining company management, understanding the mineralogy and variability in the deposit, and guiding by flowsheet and material balance. Examples of hydrometallurgical process development leading to the early use of solvent extraction in the mining industry are given.

Jan 1, 2014

By Oscar V. Mauró Obando

El presente texto describe la energía que contienen los explosivos para sensibilizar a los trabajadores que realizan las tareas de perforación y voladura. Las causas que originan los accidentes relacionados a explosivos son actos y condiciones subestándares, relacionados con el almacenamiento, transporte, manipuleo y uso de los explosivos y accesorios. En ese sentido, se busca la prevención de accidente por voladura, identificación de peligros y cómo eliminar correctamente los tiros cortados en la voladura subterránea, desde un análisis de os ingenieros de seguridad y explosivistas.

Apr 1, 2015

By Mark Vardy, Kate Dobson, Isobel Yeo, Paul Lusty, Bramley Murton

In response to anthropogenic climate change, the way in which we use and generate energy is changing. To facilitate these developments, it is essential that we increase and diversify the supply of ‘E-Tech’ elements essential for cleaner energy generation and more efficient usage. The vast majority of these materials (e.g. cobalt, lithium, niobium, platinum group metals, rare earth elements and indium) come almost exclusively from mining and new resources must be found and developed in order to secure supply and meet the demands of the future. Ferromanganese (FeMn) crusts are rich in cobalt, tellurium and rare earth metals, and are common on seafloor hard grounds at water depths over 1000 m. The mining of both FeMn crusts and nodules is potentially viable dependent of the balance of cobalt and nickle prices (Martino & Parson, 2012), however, crusts need to be at least 4 cm thick with cobalt contents of at least 0.8% (International Seabed Authority, 2008). The difficulty for those wishing to exploit these resources is firstly finding them, and secondly assessing their potential remotely. Such capability would not only save time and money, but also allow mining operations to be more focused, reducing needless destruction of seafloor habitats from exploratory mining or mining of noneconomically worthwhile deposits. In this contribution, we examine the distribution of crusts on a single Atlantic Gyot (Tropic Seamount), the morphology of FeMn crusts, their variable growth patterns and the characteristic geophysical response from crusts in various datasets, including ship based 60 m resolution multibeam and high resolution bathymetry, backscatter and sub-bottom profiler data acquired using an Autonomous Underwater Vehicle (AUV).

Jan 1, 2017

By J. de la Vergne, L. O. Cooper

The hydrostatic steel mine shaft liner (HSL) Provides a permanent wall lining for drilled shafts. It is watertight and suitable for bad ground conditions. After a shaft has been drilled to its full depth, the HSL is lowered into it and secured in place with cement grout. The liner consists of a cylindrical steel shell usually reinforced with exterior stiffening rings. The shell is basically designed for compressive strength and the rings are provided to give the shell added resistance to buckling. There are no published standards for the correct procedures to design an HSL. This paper gives a method that appears logical. A design solution can be complex with increased opportunity for error. This paper presents simple formulas to produce sufficient accuracy for construction design. Two new concepts are presented, referred to as transition pressure and critical pressure. An example demonstrates use of the formulas and concepts presented. To facilitate comprehension and use of the formulas, Greek letters are avoided and most of the English alphabet symbols used refer by association to their definitions. An appendix shows derivation of the formulas.

Jan 1, 1984

By L D. Queen

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Tifalmin porphyry copper district is located in the Star Mountains roughly 35 km north-east of the Ok Tedi mine. The district is a cluster of temporally and geochemically related porphyry copper deposits and their associated skarns. It covers an area of roughly 10 × 6 km and comprises at least three intrusions (Olgal, Futik and Kum Kom) where drilling has demonstrated the presence of porphyry copper mineralisation, and another three intrusions (Rattatat, Unfin and Pad 48) where porphyry copper mineralisation is strongly suggested by surface investigations and geochemical or geophysical signatures.Copper and gold mineralisation was first discovered in the area in the 1960s as part of the regional exploration program by Kennecott that located Ok Tedi. The mineralisation is associated with poly-phase porphyritic diorites, quartz diorites and tonalites that intrude the Upper Eocene to Middle Miocene Darai limestone and underlying Cretaceous to Eocene Feing Group. Radiometric K-Ar and U-Pb zircon ages cluster between 4 and 2 Ma for both the mineralised and post-mineral intrusions. In addition to porphyry-type mineralisation, variable amounts of calc-silicate and/or magnetite skarn occur near the contact of most of the intrusions. Mineralisation in the Olgal and Futik porphyries occurs as chalcopyrite replacement of mafic minerals and in a stockwork of micro-veinlets. Mineralisation mostly occurs in the intrusions but is also observed in hornfelsed siltstones and sandstones of the Feing Group on the southern margin of the Olgal intrusive body. Quartz veining is uncommon. Secondary magnetite is commonly associated with the highest copper and gold grades. Sericitic alteration is most prominent in the mineralised hornfels. Structurally, the area is dominated by syn- to post-mineralisation thrusting from the north. At least one of the deposits (Olgal) appears to be truncated at depth by a thrust fault.CITATION:Queen, L D, 2015. The Tifalmin porphyry copper gold district, Star Mountains, Western Papua New Guinea , in Proceedings PACRIM 2015 Congress, pp 357–360 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Webster S. Anderson

Two series of tests were run with planer model 'BB": one at the Arickaree mine of the San Francisco Chemical Co., Rich County, Utah, and one at the Roslyn No. 9 mine of the Northern Pacific Railway Co., Roslyn, Wash. The tests at the Arickaree mine were started on June 25, 1958, and continued until September 30, 1958. Prior to these tests, an electrically activated remote-control system was installed, and other modifications were made on the planer. The tests showed that the planer in general and the remote-control system worked very well; however, the various cutting tools used would not consistently penetrate and cut the phosphate rock. This indicated that the cutterhead design had to be changed before the planer would operate efficiently in phosphate beds similar to the "A" bed in the Arickaree mine.

Jan 1, 1962

By J. Pelders, G. Nelson

"Fatigue is a significant concern in the mining industry as it is a causal or contributing factor in many incidents and accidents. Fatigue can be caused by work- and non-work-related factors. There is a lack of information about associations between demographic and other non-work factors, and fatigue. This study aimed to assess associations between demographic, work, living, and socioeconomic conditions, and lifestyle characteristics, and fatigue at a platinum smelter in South Africa. Eight interviews with management and two focus groups with production workers were conducted, and 75 questionnaires were completed by production and other workers. Both work- and non-work-related factors were considered to be causes of fatigue. These factors included overtime, shift work, high workloads, activities performed outside of work, age, race, housing tenure, diet, sleep disorders, stress, and job satisfaction. In general, higher levels of fatigue were reported by younger participants, those who rented accommodation, ate less healthily, had a sleep disorder, and those with high levels of stress and low job satisfaction. As various demographic, lifestyle, and wellness-related factors were associated with fatigue, both work and non-work contributors should be addressed in fatigue management plans. BackgroundFatigue may be defined as ‘a state of impaired mental and/or physical performance and lowered alertness arising as a result of, or a combination of, hard physical and mental work, health and psychosocial factors or inadequate restorative sleep’ (BHP Billiton, 2005). Williamson et al. (2011) define fatigue as a biological drive for recuperative rest. Sleepiness and fatigue are related, and the terms are often used interchangeably. However, sleepiness, more specifically, can be defined as sleep propensity, or a person’s tendency to fall asleep (Hossain et al., 2003; Shen, Barbera, and Shapiro, 2006).Increasing levels of fatigue and sleepiness are associated with lapses in attention, errors, response slowing, fluctuations in alertness and effort, and impaired attention, working memory, long-term memory, decision-making, and creativity (Alhola and Polo-Kantola, 2007; van Dongen and Dinges, 2000). Fatigue is also associated with adverse effects on mood and impulsive behaviours (Alhola and Polo- Kantola, 2007; Minkel et al., 2011; Schwarz et al., 2013). It is a significant concern in the mining industry as it is commonly identified as a causal or contributing factor in many accidents and injuries (Schutte, 2009). Fatigue can also lead to long-term health problems, including digestive problems, heart disease, stress, and mental illness (Shaw, 2003)."

Mar 1, 2019

By Ron Millions, J. A. Folinsbee, Ishwinder Grewal, Michael Fullam, Don Strickland, Tony Y. Chong

"Since milling began in 1912, the Dome mill, now part of the Porcupine Joint Venture (PJV), has been expanded several times, the most recent increasing the milling rate from 3,500 to 11,500 tonnes per day. Dome uses conventional crushing and grinding followed by gravity concentration to recover free milling gold. A cyanidation/CIP process recovers the remaining gold in the gravity tails.Over the past few years, continuous gravity improvements have increased the gravity recovery from 20% to nearly 50% of the plant feed gold. This paper describes some of the factors that have contributed to this dramatic increase, and suggests how gravity recovery can be further improved. Gravity circuit availability has been improved to >98% with the implementation of a preventative maintenance program. More Knelson concentrators have been added to the circuit, and in 2002, an Acacia Intensive Leach Reactor was installed to replace the shaking table. In 2003, the entire gravity circuit was audited to evaluate and quantify the circuit performance. The metallurgical and mechanical operating conditions of the gravity circuit are now well understood, and areas for further improvement are well defined.INTRODUCTIONThe Porcupine Joint Venture was formed in 2002 between Placer Dome Inc. and Kinross Gold Corporation. One of the goals of the JV was to use the milling capacity of the Dome mill to process ore from Placer Dome and Kinross mines in the Timmins Camp. The PJV Dome Mill utilizes gravity concentration, cyanide leaching and carbon in pulp gold circuits to recover gold. Gravity recovery has been used in some form at the Dome Mill for most of its existence, first using conventional jigs, these being replaced in 1993 by two Knelson Concentrators, one for each of the two grinding circuits in the Dome mill. Over the years more concentrators have been added to improve the gravity recovery, most recently in 2002 for a current total of five. Also in 2002, an Acacia Intensive Leach Reactor was added to process the Knelson concentrate, replacing the shaking table."

Jan 1, 2004

By John Mitchell, Mark K. Jorgensen

Newmont Mining’s Ahafo Mine is located in Ghana approximately 300 km (190 miles) northwest of the capital city of Accra in the Brong-Ahafo region. The nearest city is Sunyani, located 45 km (28 miles) to the north. The Ahafo Mine will process ore from seven major pits that extend along a 40-km (25-mile) strike. Four pits are in the south and three pits are in the north. The resource is currently stated at 373 t (12 million oz). But it still has the potential for growth both from new discoveries and the development of underground operations.

Jan 1, 2007

By R. Hogg

The sedimentation and dewatering characteristics of flocculated slurries are determined by the size and density of the flocs. Studies of the formation and growth of flocs reveal that floc size is limited by breakage of the agglomerates due to shear in the suspension. Floc density measurements indicate that there is an inverse relationship between size and density. This relationship appears to be determined primarily by the nature of the solid particles, especially the size distribution, but it appears that agitation of the suspension can lead to some densification of the flocs, in addition to breakage. It follows that both size and density can be controlled to a significant extent by regulating the physical conditions (agitation, method of flocculant addition etc.) during flocculation. The use of physical floc conditioning to control the sedimentation and dewatering (filtration) behavior of flocculated, fine-particle suspensions is evaluated in terms of its effects on floc size end density.

Jan 1, 1986

By J. M. Mutmansky

The SIMAN (SIMulation ANalysis) computer language is a general-purpose, discrete-continuous simulation language for modeling a variety of multi-component systems. The language has been described by its author in a textbook (Pegden, 1985) and in a paper (Pegden, 1986) and is available in a mainframe version, a minicomputer version and a microcomputer version. The language was designed for and has been extensively used for modeling manufacturing systems but possesses many features that are advantageous in the modeling of mining materials handling systems. Consequently, the authors have applied the language to the simulation of an open pit shovel/truck operation to test its usefulness for simulating mine materials handling systems. This paper presents a short background on simulation languages, the capabilities and modeling framework of the SIMAN language, a description of the application of SIMAN to a shovel-track operation and some results and conclusions on the use of the language for mining materials handling systems.

Jan 1, 1988

By Thomas W. Smelser

A full-scale geotechnical model of a 15-foot (4.6 m) wide coal mine entry in correlation with computer finite-element analysis (FEA) is being employed at the Bureau of Mines Spokane Research Center for basic research on roof-bolt support systems. Physical and computer modeling of various coal mine roof-bolt reinforcement systems will increase our basic knowledge of how roof supports function. This information, in correlation with computer FEA and underground verification tests, will provide a basis for establishing safer, more cost- effective roof control plans and help establish guidelines for employing fully grouted and conventional bolting systems. The basic rationale for the research, research approach, methods and equipment employed, results to date, and future research plans are described in this paper.

Jan 1, 1982

By L. E. Mordberg, E. N. Nesterova

Geochemical studies of the bauxite deposits show that the primary composition is gibbsitic. Some trace elements were relatively mobile during bauxite formation with the content of Th, U and Zr increasing and that of Rb, Ni and Co decreasing. Y and Pb were relatively immobile during lateritisation; their contents and ratios were inherited from different types of underlying rocks. The supply of Ni and Co took place at the diagenetic or epigenetic stages; their ultimate source was the crystalline basement in the region. The studies support the view that the bauxite was likely to have originated as a result of in-situ lateritisation and not through sedimentary transport and redeposition

Jun 18, 1905

The distribution of chrome spinels in a magnetically fractionated ilmenite concentrate sourced from the Murray Basin was characterized by XRF assaying, quantitative electron microprobeanalysis, grain mapping, automated mineral phase clustering, and modal analysis. At least 14 distinct chrome spinel types were present in the concentrate. There is considerable variation in the amount of each chrome spinel type present, although a high-Mg, high-Al phase makes up close to 45 per cent of the total spinel population. Magnetic fractionation results showed significant variation in the composition and relative abundance of spinels reporting to each fraction. Low magnetic field strength fractions (ie. high susceptibility grains) were dominated by chrome spinels that are mid-range in Al and Cr. These spinels have the highest magnetite, ulvospinel and Fe(Al,Cr)2O4components. In comparison, the high field strength fractions (i.e. low susceptibility grains) have the majority of the grains with high-Al contents indicating a higher proportion of Mg(Al,Cr)2O4component. Spinels high in a (Al,Cr)2.67O4non-stoichiometriccomponent are absent at low field strengths but tend to be concentrated in the high field strength, non-magnetic fractions. Intermediate field strength fractions tend to exhibit a broad spread in spinel compositional types. A mild roast treatment of the sample had no clear effect on the distribution of chrome spinels between different magnetic fractions, but it did cause a change in the magnetic properties of the accompanying ilmenite grains. The effect of more extreme roasting conditions on the magnetic properties of the chrome spinels is to be determined.

Jan 1, 2003

By Nicolás Caussade

"The IMPC 2014 slogan "Optimizing Water and Energy Usage for Sustainable Mining" refers to the ever decreasing availability of fresh water and energy, which has turned out to be a crucial aspect in assuring the competitiveness of the mining sector in Chile and the Andes region in general. The concern for sustainability and the supply of water and energy is nowadays part of the top priorities of mining countries and communities. This is also the case for Antofagasta Minerals. Several years ago its mining group implemented an energy policy based on intelligent, strategic and sustainable management, in order to successfully face the challenges imposed by the market. It is called an intelligent policy because it intends to provide energy through a diversified range of sources, which includes the development of in-house alternatives. It is also a policy focused on efficient energy consumption and one that is strategic. Because it is in line with the characteristics of the mining activity, it is developed for the long term. Finally, what makes the policy sustainable is that it gives priority to energy usage from renewable resources and as such, the required capacities have been developed to generate innovative solutions that respond to the restrictions that characterize the industry today."

Jan 1, 2014