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By Mark Sanders

This report describes an experiment which was conducted to compare the relative bumping hazard of a low and high profile hard hat (helmet) in a low seam mining environment. The study was specifically designed to assess the effect of lowering the helmet profile on frequency of head impacts in an underground low seam coal mine simulator. This involved subjects performing four common low coal mining tasks wearing the low and high profile helmets in the low seam simulator (36" and 48? heights). The results of the study indicated that a low profile helmet could reduce bumping frequency in underground low coal approximately 25%, and as much as 80% on selected tasks. It was beyond the scope of the study to measure the impact force, thus it was not possible to estimate the effect of the low profile helmet on severity of impacts underground. The research team recommended that a more extensive investigation be made of head injuries experienced in low seam mining (both underground and surface) with the objective being to assess the impact of a low profile helmet on total head accident exposure.

Jan 1, 1980

Abstract : The computation of reliability index or failure probability of slopes can be transformed into an optimisation problem. In high rock slope engineering, it is usually a multimodal optimization problem. The traditional optimization techniques are difficulty to find out the global optimal solution because of their easily falling into local optimal value. Recently, a new kind of bionic algorithm - ant colony algorithm (ACA) - has been used to solve this problem. In this paper, the structure of ant colony algorithm and the transfer probability of ants are modified to evaluate the failure probability of complicated slopes. A new adaptive ant colony algorithm (AACA) is proposed to determine critical slip surface and its corresponding failure probability of complicated slopes. A case study is given to verify the proposed approach. The results show that the presented method has obvious advantages compared with traditional methods. ZUSAMMENFASSUNG: Die Rechnung des Zuverlaessigkeitindexes oder der Zerstoerungswahrscheinlichkeit kann sich in einer Optimierungsfrage umwandeln, im Bauprojekt an hoehe Gebirgehang, handelt es sich meistens um eine Optimierungsfrage ueber Multi- Spitzenwert. Mit der traditionelle Optimierungsmethode ist es schwer eine umfassende Loesung fuer die Optimierung zu finden wegen des leichte Verfallens in Beschraenkung der Teiloptimierungsloesung. Mit dem neue Bionik- Algorithmus —— Ameisen - Kolonie- Algorithmus wird dieses Problem geloest. In diesem Text hat man eine Strukturverbesserungsloesung fuer das Ameisen- Kolonie -system und die Wahrscheinlichkeit der Ameisenkolonie erwaehnt, und damit wird man die Zerstoerungswahrscheinlichkeit des komplizierte Hangs feststellen. Mit dem neuen Ameisen- Kolonie- Algorithmus kann man die gefaehrlichste Gleitflaeche und die entsprechende Zerstoerungswahrscheinlichkeit herausfinden. Die in diesem Text beschriebene Methode wurde durch Praxis geprueft. Durch die Pruefergebnisse wurde es gezeigt und bestaetigt, dass der neue Bionik- Algorithmus vorteilhafter als der traditionelle Algorithmus ist. Résumé : Le calcul de l’indice la fiabilité ou de la probabilité de ruptures peut être transformé en un problème de l’optimisation. Pour le cas du génie des pentes de haut rocher , le problème se pose en général en l’optimisation de multi-crêtes. Les techniques traditionnelles conduisent facilement à la solution optimal partielle au lieu de celle globale. Récemment un nouveau type de bionique algorithmique a été appliqué pour la solution de ce genre de problèmes, c’est l’Algorithme Colonie de Fourmis. Dans l’article il est proposé de modifier la structure du système de la colonie de fourmis et la probabilité de transfert des fourmis en vue d’évaluer la probabilité de ruptures des pentes de haut rocher complexes, par ailleurs un nouveau algorithme adapté de colonie de fourmis est formulé pour déterminer la surface glissante critique et la probabilité de ruptures correspondante. Les techniques proposées dans l’article sont vérifiées à travers des expérimentations dont les résultats ont prouvé que les techniques présentées dans l’article sont évidemment meilleures que celles traditionnelles.

Jan 1, 2003

When overburden depth exceeds economical recovery in openpit coal mines, the use of highwall mining systems has increasingly come into play. However, stability in the highwalls is always a major safety concern during such mining. The U.S. Mine Safety and Health Administration requires that highwall mining operators follow ground control plans that specify the pillar sizes necessary to prevent collapse that would threaten highwall stability.

Jan 1, 2006

By S. Vorberg, J. Preussner, B. Fischer, U. Glatzel, R. Völkl, M. Wenderoth

Pt-Al-X alloys have shown good mechanical properties and adequate oxidation resistance. Starting from a promising Pt-Al-Cr alloy, the influence of Ni additions was investigated. After ageing finely dispersed precipitates are observed. Nb, Ta, Ti and Re increase strength when added as partial substitute for Al. Minor additions of B increase creep resistance and rupture time remarkably, owing to strengthening of the grain boundaries. The evolution of the alloy development programme as well as selected properties of the multi-component Pt-base alloys are presented.

Jan 1, 2006

By M. E. Poad

Structural properties of steel-fiber-reinforced shotcrete and polymer-impregnated shotcrete, both plain and fiber-reinforced, were investigated by the Federal Bureau of Mines, Spokane Mining Research Center. The research center has found that flexural strengths can be increased by as much as 106 percent, and splitting-tensile strength by 50 percent, by introducing randomly oriented steel fibers. A slight decrease of compressive strength was found in the fiber-reinforced shotcrete. Polymer-impregnated shotcrete exhibited a threefold to fourfold increase in compressive and splitting-tensile strength. The techniques of preparing shotcrete with the dry process, using both fast-set agents and regulated-set cement, are described, along with the results of physical-property testing. Physical properties include compressive and splitting-tensile strengths, tangent and secant moduli, and stress-strain curves for plain shotcrete, fiber-reinforced shotcrete, and polymer-impregnated plain and fiber-reinforced shotcrete. Flexural strengths for plain and fiber-reinforced shotcrete are also reported. Steel-fiber shotcrete is the more promising of the new structural materials for ground support, and additional research is recommended.

Jan 1, 1975

By Roger J. Morrell

Bureau of Mines laboratory experiments with reduced scale cutter and cutter forces were performed to (1) define the fundamental relationships governing disk cutter performance and (2) to develop a method of predicting disk cutter performance in soft, medium, and hard rocks. The rock cutting experiments were performed in four igneous and metamorphic rocks that ranged in compressive strength from 38,000 to 67,000 psi. A special testing machine called a linear cutter apparatus (LCA) was used to load and traverse a free rolling disk cutter across a smooth rock surface. Each pass of the disk produced a single crater, and runs were spaced to avoid breakage between craters. During each run the normal and tangential cutter forces were measured and recorded. The soft and medium rock data were obtained from previous Bureau experiments with disk cutters. Crater depth, tangential cutter force, crater volume, specific energy versus normal cutter force, and crater width versus depth are defined within this study. With the use of standard physical properties, performance prediction equations were developed using stepwise linear regression analysis techniques. A method of using these prediction equations to calculate the boring rate, the cutter spacing, and the torque and energy requirements of a full-scale boring machine was also developed.

Jan 1, 1974

By M. W. Hildyard, M. O. Kataka

Seismic integration schemes aim to incorporate the rock mass response provided by the historical seismic activity to improve the ability of numerical models to reproduce future response to mining. Up to now, integration schemes considered the events using quasi-static models. This paper presents case studies that consider some of the seismic and modelling issues needed to extend these schemes to include the dynamic characteristics of seismic events. The ultimate aim of an automated integration scheme seems impractical for dynamic modelling. The predictions of the WAVE elastodynamic finite difference program are, however, suitable for modelling limited numbers of events to determine either the near-field velocities and damage or the effect of fractures and excavations on the far-field low frequency response. Les projets d’intégration sismique ont le but d’incorporer la réponse de la masse rocheuse à l’activité sismique historique pour améliorer la capacité des modèles numériques à reproduire la réponse future à l’exploitation minière. Jusqu’à présent, les projets d’intégration étudiaient les évènements avec des modèles quasi-statiques. L’étude présente révèle des études de cas qui considèrent certaines des questions concernant modelage et séismes qui sont nécessaires pour porter plus loin ces projets en incluant les caractéristiques dynamiques des évènements sismiques. Le but final d’un projet d’intégration automatisé semble impraticable pour la modélisation dynamique. En revanche, les prédictions du programme élastodynamique par la méthode des différences finies WAVE sont appropriées à la modélisation d’un nombre limité d’évènements de façon à déterminer soit les vitesses à petite échelle et les dommages, soit les effets des fractures et excavations sur la réponse de basse fréquence à grande échelle. Seismische Integrationsschemata zielen darauf ab, Reaktionen der Gesteinsmasse, die von den Berichten seismischer Aktivitäten stammt, zu inkorporieren um numerische Modelle in die Lage zu versetzen, künftige Antwort zum Bergbau zu reproduzieren. Bis dato betrachteten Integrationsschemata die Fälle mit quasi-statischen Modellen. Diese Arbeit stellt Fallstudien dar, die einige der seismischen und modellierenden Fragen betrachten, die benötigt werden, um diese Schemata auszuweiten, um die dynamischen Charakeristika seismischer Fälle einzuschließen. Das Endziel eines automatisierten Integrationschemas erscheint für das dynamisches Berechnen undurchführbar. Die Vorhersagen des WAVE elastodynamisch begrenzten Unterschiedprogramms sind jedoch verwendbar für das Berechnen von begrenzten Anzahlen von Fällen, um entweder die Nahfeldgeschwindigkeiten und Schaden oder den Effekt von Brüchen und Extraktionen auf der Fernfeld Niederfrequenzantwort festzustellen.

Jan 1, 2003

By P. -E. Boileau, P. Marcotte, Y. Aldien, S. Rakheja

A number of biodynamic models of the hand-arm system have evolved on the basis of measured driving-point mechanical impedance (DPMI) responses to facilitate analyses of the coupled hand-tool system [1]. The parameter identifications in such models are based upon minimization of an error function of the model and the target impedance data, which may not yield a unique solution. Consequently, a number of model structures and parameter sets could be realized that would equally satisfy the target curve. Moreover, the vast majority of the reported models exhibit acute deficiencies due to excessive static deflections of model masses, presence of a low frequency mode and very light masses in the order of 1.2- 4.8 grams. The models also do not characterize the dependency of the biodynamic responses on many factors, namely the hand forces, hand-arm posture and vibration intensity. This study aims at development of a hand-arm biodynamic model with considerations of the hand forces, and both the DPMI and power absorption measures, to enhance the uniqueness of the model. Methods Two different model structures are chosen for identifying the model parameters on the basis of measured DPMI and absorbed power characteristics of the hand-arm system under zh-axis vibration over a range of hand-grip and push forces. Owing to the strong influence of the hand-handle coupling forces, the models were initially derived for fixed hand forces, namely 30 N grip and 50 N push forces, as suggested in the ISO 10068 standard [2]. The equations of motion for the model are formulated and solved to compute both the DPMI and absorbed power responses. A constrained minimization function comprising weighted errors of both the DPMI and absorbed power is formulated and solved to identify the parameters. Alternate functions corresponding to different combinations of hand forces are then applied to identify hand-force dependent model parameters. Variations in the model parameters are investigated as functions of the grip, push and coupling forces through linear regression analysis. Regression-based models are formulated for deriving the hand-handle forces dependent model parameters. The validity of the model is also examined under selected combinations of hand forces. [ ]

Jan 6, 2006

By T. Bertke

This document assesses the environmental aspects of a preliminary design for processing kaolin clay as the domestic resource for recovery of alumina by a hydrochloric acid leach-HCl gas induced crystallization process. The report covers waste sources, control measures, and potential environmental and health effects applicable to the process technology.

Jan 1, 1980

By Stuart Brashear, Lee Schettler

The effect of water on several ANFO/emulsion blend ratios are documented by both physical observations and analytical testing to demonstrate the effect even small quantities of water can have on water resistant blends.

Jan 1, 1996

By H Bibby

Initial analysis of Long Offset Time Domain Electromagnetic (LOTEM) data has traditionally been made in terms of early and late time apparent resistivities. By using more than one grounded bipole as a source, a tensor analysis technique analogous to the method used to analyse DC resistivity multiple-source bipole-dipole surveying may be formulated. We define the æinstantaneous apparent resistivity tensorÆ as the tensor that relates the total electric field vectors at each instant to the steady state (DC) uniform half space current density vectors due to each source. Instantaneous apparent resistivity tensors calculated for a 3D resistivity model suggest that profiles of LOTEM measurements across simple 3D structures can be used to create an image that reproduces the main features of the subsurface resistivity. Where measurements are distributed over an area, maps of the tensor invariants or the tensor ellipses at different times can be made into a sequence of images which provide a way of ætime slicingÆ down through the target structure.

Jan 1, 1996

By A. D. Fowler, M. T. Anderson

A phenomenological model is presented that relates Pb-Zn mineralisation to proximal geopressure zones. Typically, geopressure zones (GPZ) consist of masses of undercompacted sediment encapsulated within impermeable shales and are characterised by high formation fluid pressures. Heat flow is perturbed in some GPZ on account of their insulating properties. Geothermal gradients as high as 150 degrees C/km have been observed over short distances in the sediments of the US coast of the Gulf of Mexico. Some modern geopressure zones are known to reach temperatures of 120-150 degrees C at depths of 2.5-3.5 km. It is demonstrated that the zones may act as proximal sources of hydrothermal fluids, thus explaining the high temperatures of mineralisation observed in the deposits, which are hosted in basins characterised by thick, rapidly deposited, shale-rich clastic sequences

Jan 1, 1991

Separation of Nickel and Cobalt from Manganese, Magnesium and Calcium by Synergistic Solvent Extraction - From Batch Tests to Pilot Plant Operation The synergistic solvent extraction system consisting of Versatic 10/LIX63/TBP was used for the separation and purification of nickel and cobalt from synthetic laterite leach solution after iron removal. Very encouraging results were obtained for separating nickel and cobalt from manganese, magnesium and calcium. In batch tests, the organic composition of the synergistic system was optimised and very large synergistic shifts for nickel and cobalt were observed. The ?pH50(Mn-Co) and ?pH50(Mn-Ni) values were as large as 1.65 and 2.40, respectively. The extraction and stripping kinetics of nickel and cobalt was fast. Semi continuous extraction tests were conducted with a pH profile of 5.5/6.1/6.5 in three stages at 40¦C. The nickel and cobalt extractions reached 99.9 per cent with only 5 mg/L Ni and <1 mg/L Co left in the raffinate. With two stages of scrubbing, only 2 mg/L Mn and less than 1 mg/L Mg and Ca were left in the scrubbed organic solution. With two stripping stages, the stripping efficiencies of Ni and Co reached over 95 per cent. A fully continuous pilot plant operation was conducted successfully for 280 hours. With an O/A ratio of about 2 and a pH profile of 5.5/5.8/6.0/6.3 for the four stages EX1/EX2/Ex3/EX4, both nickel and cobalt were almost completely extracted. Using a pH profile of 5.4/5.0 for SC1/SC2, the manganese scrubbing efficiency was over 96 per cent. Using three strip stages, over 98 per cent Ni and 99 per cent Co were stripped with only 64 mg/L Ni in the stripped organic solution. The nickel concentration in the loaded strip liquor reached 83 g/L, resulting in a ?Ni of over 28 g/L. The chemical stability of the system was also assessed over 12 weeks under proposed industrial operating conditions. Operation exclusively under strip conditions at 50¦C and 40¦C resulted in LIX63 oxime half lives of 1.1 and 2.1 years, respectively. Operation exclusively under extract conditions at 50¦C and 40¦C resulted in oxime half lives of 0.26 and 0.82 years, respectively. Losses of Versatic 10 were less than four per cent.

Sep 13, 2010

By A. K. Das, S. Pathak, C. Bhanu, P. K. Tripathy

Ferroalloys are integral part of steel melting process. The purpose of using ferroalloys is three fold e.g. killing of steel, modifying the slag composition and steel alloying. Amount of ferroalloys used for alloying is subject to requirements of steel properties e.g. yield strength, ductility, formability etc. Variety of ferroalloys (some-times pure metal) is used by steel industries depending upon their techno-economic feasibility. Size, chemistry and modes of addition of ferroalloys are suitably engineered to bring in operational consistency and cost benefits. Of late, Tata Steel has tried out a few ferroalloys for the first time with interesting results to meet the specific requirements of high strength interstitial free (IF) and micro-alloyed steels. Some of these ferroalloys have been put into regular use with complete or partial replacement of ferroalloys used earlier. Size of one of the ferroalloys has also been modified without any other adverse effects. This paper summarizes requirements of ferroalloys for the steel industry with special emphasis on recent trials.

Jan 1, 2007

By L. M. Gould

"Syncrude Canada operates the largest oil sands crude oil production facility in the world and produces over 13% of Canada’s total oil requirements. To achieve this, Syncrude mines the oil sands in open pits, extracts the raw oil known as bitumen from the sand using water-based processes and upgrades it into sweet light crude oil by fluid coking, hydroprocessing, hydrotreating and reblending. The final product, Syncrude Sweet Blend (SSB), is sent by pipeline to three Edmonton area refineries and then to pipeline terminals which ship the SSB to refineries in Canada and the United States.As parts of the Mildred Lake base mine reached their economic life, they were replaced with new facilities at the Aurora Satellite mine. Aurora is situated on Oilsand Leases 10, 12 and 34, 35 km northeast of the Mildred Lake facility (Fig. 1).In 2000, the first hydrotransport low-energy extraction production train started up at Aurora. A second production train is scheduled for start-up in 2003. Open pit mining at Aurora occurs using two hydraulic shovels, two cable shovels, and trucks ranging from 320-ton to 380-ton payload capacities (Fig. 2).Once the oil sands is excavated, the trucks dump the ore into a crusher designed to break up the big lumps of oil sands and rock at peak rates of 11 000 t/hr. The ore is then transferred by conveyor to a surge pile and then to a mixing box which combines the oil sands with hot water. Following bitumen separation in the primary separation vessel, froth is delivered to Mildred Lake for processing via the intersite pipeline (Fig. 3).The goal of this paper is to illustrate how high precision shovel GPS (HPGPS) is being used at the Aurora mine to aid in mine planning. This can be accomplished by first describing the function of the mine planning department, describing the Aurora orebody, and finally explaining how the HPGPS system functions and how it is employed at Aurora.The short range mine planning department ensures a steady supply of ore is delivered to the plant at the desired grade in a sequenced and economical manner. This is done by creating a mine plan that consists of shovel dig locations that require the shovels to mine in a specified area at a specified elevation."

Jan 1, 2002

Council for 1999/2000 President J.R. Dixon President Elect M.H. Rogers Vice Presidents Senior Dr L.A. Cramer Junior A.A.B. Douglas Immediate Past President R.P. Mohring Honorary Treasurer J.A. Cruise Members of Council B.C. Alberts Dr N.A. Barcza N.J. Barkhuysen R.D. Beck M.J.P. Bierman Prof. A.N. Brown D. Cockcroft Dr M.B. Cortie Dr L.A. Cramer J.A. Cruise E.G. de Villiers J.R. Dixon A.A.B. Douglas F.M.G. Egerton J.P.W. Fisher C.E. Fivaz K.J.R. Ford Prof. G.A. Fourie R. Graham Dr R.G. Gürtunca Dr R.V.R. Handfield-Jones* M.C. Harris J.P. Hoffman H.E. James P.J. Knottenbelt R.P. Mohring H.G. Mosenthal G.Y. Nisbet N.M. O'Brien R.G.B. Pickering Prof. R.P. Plewman S.J. Ramokgopa Prof. R.E. Robinson M.H. Rogers D.A.J. Ross-Watt Prof. R.F. Sandenbergh Dr H. Scott-Russell C.B. Sheppard D.A.A. Smith Dr T.R. Stacey Dr O.K.H. Steffen D.J. van Niekerk J.C. Viljoen J.N. Wallington

Jan 1, 1999

The National Mining Hall of Fame will hold its 13thAnnual Induction Banquet during MINExpo International 2000 in Las Vegas, NV. The gala black-tie (optional) event will honor eight legendary leaders of the mining industry. The event will take place at the Las Vegas Hilton Hotel on Sunday, Oct. 8. The induction ceremonies will salute mining greats elected by the board of governors from a list of nominees submitted by mining industry partners and the public. The members of the Class of 2000 will join 151 other inductees enshrined in the Mining Hall of Fame in Leadville, CO. The evening will begin at 6 pm with a cash bar reception followed by the banquet and program at 7 pm. Keynoting the banquet program will be Harrison (Jack) Schmitt. He was the geologist/astronaut of the Apollo 17 mission to the moon in 1972 (see related story on page 26). And he is the only scientist to “kick rocks on the moon.” Schmitt is also a member of the Mining Hall’s board of governors. Schmitt was also the keynote speaker at the First Annual Induction Banquet in Denver, CO in 1988.

Jan 1, 2000

By R Edwards

Greater efficiency of capture of minus 6 mm to fine micron size particles of free gold is achieved with the Knelson Concentrator. The development, principles of operation and recent innovations relating to this enhanced gravity concentrating device are described by the inventor, followed by a description of application and consequent economic benefits in low grade alluvial gold deposits by a large scale user of Knelson Concentrators in the Northern Territory of Australia.

Jan 1, 1990

By S. Banisi, J. Marois, A. R. Laplante

"This paper compares the behaviour of gold and ore in the grinding circuit of Hemlo Gold Ltd. Particular attention is given to grinding kinetics, classification behaviour, and liberation. For grinding kinetics, laboratory grinding of gold flakes and silica, 840-1200 um in size (14/20 mesh), was also performed to provide a standard for comparison and to study in a controlled environment the mechanisms of breakage, folding, smearing and impacting.Grinding kinetics were characterized at laboratory scale with breakage and selection functions. The breakage function showed that 75% of gold disappearing from the 840-1200 um class reported to the 600-840 um; this figure is much higher than for silica ( 46%) or most other minerals, and implies that comparatively fewer fine fragments are produced from the breakage of gold flakes, on account of gold's malleability. The selection function of silica was four times that of gold. At plant scale, the ratio of the selection function of ore and gold increased from 6 for at 50-100 um to 20 at 500-1000 um.Observation of original flakes and their fragments with the scanning electron microscope showed that the main mechanism of ""grinding"" from the 840-1200 um to the 600-840 um class was folding rather than actual breakage. This was confirmed by a measure of individual flake weight. The postulated breakage cycle is that relatively globular flakes become increasingly serrated through grinding; they can then regain their original shape through folding and reflattening into cylindrical and spherical shapes, as the majority does; however, some fragments will at this point undergo actual breakage. Photographic evidence is presented to support the proposed mechanisms.Smearing of gold unto silica was observed when silica was ground after a gold, and embedding of silica into gold flakes when gold was ground after a silica. Both mechanisms occur whenever gold and harder minerals are jointly ground, and result in ""unliberation"" of gold. It is postulated that smearing of gold onto other minerals plays an important role in explaining how gravity recovery can increase overall gold metallurgy, especially when used ahead of flotation.Classification of gold in the primary hydrocyclones takes place at a much finer cut-size than ore, 20 vs. 57 um. This and the slower grinding kinetics result in high gold circulating loads in the primary loop, 6700%, and a gold content in the primary cyclone underflow (PCUF) is twenty four times that of the ore. The gold size distribution for primary cyclone overflow is much finer than that of the ore, although they are essentially similar in the PCUF.Liberation, or more accurately ""gravity recoverability"", was assessed with a 7.5 cm (3"") Knelson concentrator. It varied between the thirties for the primary mill discharge and two cyclone overflows, to highs of 89 to 92% for the PCUF and secondary mill discharge, 89 and 92%, respectfully."

Jan 1, 1991

An Integrated Study of Bubble-Particle Attachment Mechanisms

Sep 13, 2010