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By P. J. Foster

A common theme running through recently introduced mining health and safety legislation in many parts of the world is risk assessment. Most recently, risk assessment legislation has been introduced across the mining industry of South Africa and the view that the introduction of risk assessment based legislation provides an ideal opportunity to improve on past health and safety performance is presented. Risk assessment techniques range from highly complex safety system techniques that are used in high technology process industries, to subjective techniques based on simple judgements that are finding use in many other industries. The objective of this paper is to shed some light on risk assessment, not by detailing the risk assessment process but by identifying the crucial elements that need to be considered if risk assessments are to be successful in changing health and safety performance. A case study is presented illustrating the introduction of risk assessment into the Ingwe Coal Corporation, one of South Africa?s largest mining houses, to indicate how the system was developed and how it is being used.

Jan 1, 1998

By JAMES J. PURDY

The great majority of stokers used in residential heating installations are of the clinkering type. Because of inherent characteristics of the under- feed combustion process as it occurs in these small stokers, and because of the wide range of operating conditions encountered in residential heating schedules, not all bituminous coals can be used successfully in residential underfeed units. The problem of providing consumer satisfaction has been attacked by the joint efforts of the stoker manufacturers and the coal industry; the stoker manufacturers have been concerned with improving their product to permit the use of a wider range of coals, and coal operators have made every effort to market selected and better prepared coals. In view of the wide range of physical characteristics and chemical properties of bituminous coals, the problems are real and are receiving increased attention.

Jan 1, 1949

This paper considers three aspects of cemented fill practice and research in Mount Isa. Firstly, an account is given of the use of Portland cemented hydraulic fill, considering mainly the role and specifications of the fill used but including û brief description of fill preparation and placement. Data resulting from a Portland cemented hydraulic fill sampling, curing and testing campaign covering about 18 months of operating practice are presented, analysed and discussed. These yield information indicating the mode of operation of a fully-automated fill preparation station, as well as a means of comparing field and laboratory strength results. A technique with potential for use as a fill quality control without actual strength testing is also described. Results of a fill research program conducted by the author in Mount Isa since early 1968 are presented, involving both Portland cemented hydraulic fill and alternative, cheaper, additives for cementing hydraulic fill.

Jan 1, 1971

By Stefan Aronsson, K. Rainer Massarsch

"ABSTRACT The geology of Sweden is characterized by the most recent glacial period with deposition of very soft clays and loose sand. Due to these difficult geotechnical conditions, new, innovative foundation and ground improvement methods were developed, which today are used in many other countries. Over centuries, Swedish scientists and engineers have made important contributions to the developments in foundation engineering. An important aspect of the success of Swedish foundation engineering in practice is the spirit of close cooperation between practitioners, engineers, and scientists. This has been achieved by the establishing of commissions, with the aim of finding solution of geotechnical problems. The paper focuses on developments in foundation engineering during the last century and does cover present activities in Sweden.IntroductionSoil mechanics and geotechnical engineering play an important role in Swedish society, as most construction activities require the consideration of foundation conditions. The objective of the paper is to summarize important developments in foundation engineering, primarily during the past century, which have influenced geotechnical engineering also in other countries. These achievements are the result of contributions by scientists, engineers and practitioners, only a few of which can be named. The paper does not claim to cover all aspects of geotechnical engineering, as emphasis is on the solution of foundation engineering problems from an international perspective. Thus, ongoing or recent research and development projects and activities within the geotechnical community are not included, as this would exceed the scope of the paper.Over the centuries, Swedish scientists and engineers contributed to the development of civil and foundation engineering. One important reason is the geology of Sweden, which is characterized by the most recent glacial period, resulting in the deposition of soft clays and loose sands in the coastal areas and dense glacial till in the interior of the country. Geotechnical engineering in Sweden has a long tradition and early contributions by several Swedish engineers and scientists have had a profound influence on the current foundation design in and beyond Sweden. A description of early Swedish geotechnical engineering has been presented in several publications by Flodin and Broms (1981), Broms and Flodin (1988), Massarsch and Fellenius (2012). The historic development of Swedish geotechnical and foundation engineering can be divided into four periods. During the “Early Era”, engineers were active in different sectors of military, civil, and mining engineering. Next, the “Industrial Era” comprised developments during the industrial revolution, when the transportation infrastructure of the country was modernized and extended. During the third period, possibly the “Golden era” of Swedish geotechnical engineering, which started at the end of the 19th century and lasted the following fifty years, geologists, engineers and scientists helped to establish modern geotechnical engineering. But also during the recent past, the “Modern Era”, several important contributions to geotechnical and foundation engineering which originated in Sweden, are used in many countries today."

Jan 1, 2014

By R. Raghavaraju

Estimation of the dynamic stress field in terms of its amplitude and decay around a blast hole is a key input parameter in all numerical modeling and blast prediction exercises. However, there is very limited information available in literature on these critical parameters, which would be considered essential in any blast modeling exercise. A laboratory-scale experimental study has been carried out in two different rock types to study at very close range the stress wave decay from a blast hole at distances ranging from 3 to 10 borehole radii. The single–hole blasting experiments employed a centrally located detonating cord (5.3 g/m) in 6 mm(1/4 inch) and 10 mm (3/8 inch) boreholes. The coupling medium employed was air and water, in addition to using a thin-walled copper tube in intimate contact with borehole wall to prevent of penetration of explosion gases into the emerging cracks. The paper describes the nature (amplitude and decay) of the transmitted shock pressure and their evolution in the two rock types for these various experimental conditions, which are present to varying degrees in all blasting operations.

Jan 1, 2014

By P. H. S. W. Kulatilake, B. Malama

To simulate brittle rocks, a mixture of glastone, sand and water was used as a model material. Thin galvanized sheets were used to create joints in blocks made out of the model material. To investigate the failure modes and strength, both the intact material blocks as well as jointed model material blocks of size 35.6 × 17.8 × 2.5 cm having different joint geometry configurations were subjected to uniaxial and biaxial compressive loadings. Results obtained from the intact model material blocks are used to validate a new intact rock failure criterion for biaxial loading. Results obtained from both the intact and jointed model material blocks are used to develop a strongly non-linear new rock mass failure criterion for biaxial loading. In this failure criterion, the fracture tensor component is used to incorporate the directional effect of fracture geometry system on jointed block strength. The failure criterion shows the important role the intermediate principal stress plays on rock mass strength. Zur Simulation spröder Gesteinsarten wurde ein Modellmaterial aus Dentalgips, Sand und Wasser hergestellt. Daraus wurden Blöcke gegossen, in denen mittels dünnen, galvanisierten Blechen Trennflächen erzeugt wurden. Die Blöcke mit Abmessungen von 35.6 × 17.8 × 2.5 cm wurden in einaxialen und biaxialen Druckversuchen belastet. Es wurde das Versagensverhalten und die Festigkeit von intakten Blöcken sowie durchtrennten Blöcken mit unterschiedlicher Trennflächengeometrie untersucht. Aus den Ergebnissen der Versuche an intaktem Material wurde ein neues Versagenskriterium für biaxiale Belastungen validiert. Die Ergebnisse der Versuche an intakten und durchtrennten Blöcken wurden verwendet, um ein neues stark nicht-lineares Versagenskriterium für geklüftetes Gebirge unter biaxialer Belastung abzuleiten. Darin wird der Bruchtensor verwendet, um den Einfluss der Trennflächengeometrie auf die Festigkeit zu erfassen. Das Versagenskriterium stellt heraus, welche Bedeutung die mittlere Hauptspannung für die Gebirgsfestigkeit hat. Un mélange de platre dentaire, de sable et d’eau a été utilisé pour développer un matériau analogue des roches fragiles. De fines feuilles galvanisées permettent de créer des discontinuités représentatives des discontinuités naturelles dans des bloques fabriqués avec ce matériau analogue. Les modes de rupture et la résistance, tant pour le matériau intact que pour le matériau avec ses discontinuités, ont été étudiés sur des blocs de 35.6 × 17.8 × 2.5 cm soumis à des efforts de compression uniaxiaux et biaxiaux. Différentes configurations de géométrie de discontinuités ont été considérées. Les résultats obtenus à partir des blocs intacts permettent de vérifier un nouveau critère de rupture pour les roches intactes soumises à des efforts biaxiaux. Les résultats obtenus, tant avec les blocs intacts qu’avec les blocs avec discontinuités, sont utilisés pour développer un nouveau critère de rupture, fortement non linéaire, pour les massifs rocheux soumis à des chargements biaxiaux. Dans ce critère de rupture, un tenseur de fractures est introduit pour caractériser les effets directionnels de la géométrie des systèmes de discontinuité sur la résistance des blocs avec discontinuités. Ce critère de rupture démontre le rôle important de la contrainte principale intermédiaire sur la résistance des massifs rocheux.

Jan 1, 2003

By H. K. Lin, J. L. Oleson

The purpose of this study is to develop a mathematical model to describe the oxidation of cyanide with SO2as proposed in the Inco process. This research employed a direct method for measuring the change in cyanide concentration with respect to time as effected by varying concentrations of SO2, copper and pH. Developing this model may be applicable in determining optimum conditions in a process well known and used in the mining industry. It was determined that the reaction is first-order with respect to cyanide, SO2and [Cu+2].The reaction order is 0.15, or zeroth order with respect to [H+] at pH range from 8.0 to 9.5.The activation energy, Ea, is 21.6 kJ/mol. The overall rate equation, as determined through this study is: [ ]

Jan 1, 2004

By Orr C. W

Continuing the systematic investigation of the influence of elements on the properties of lead(1). If the effects of additions of copper (up to 0.3%) on Port Pirie lead have now been determined in so far as creep rate is concerned.The results in the present paper contain also a survey of the influence of copper on the micro-structure of lead, a feature which has not appeared in the previous papers of this series. Further, it has now become known that creep is but little related to the more usually determined properties such as hardness and tensile strength. Since, however, these properties are of considerable importance in connection with the fabrication and use of this metal. Brinell hardness determinations have also been made and are here included.It is becoming more and more realised also that to be useful, creep data should refer to stresses of the order of those used in practice. This is due to the fact that as soon as deformation takes place, the properties of the metal are automatically changed. Lead does, of course, creep during industrial use, and probably (in lead chamber construction for example) extensions of the order of 5%...

Jan 1, 1938

By E. Herrera Alarcón, L. Mariscal Samaniego

The Teniente Converter (wet charge type) was commissioned in august 1995 and was designed to smelt 744 tpd (metric tons per day) of dry copper concentrates. Its products are white metal (73% Cu) that is sent to the Peirce Smith converters, slag that is cleaned in Reverberatory Furnaces and the process gases that are sent to the Sulfuric Acid Plant. Since its start up, the Teniente Converter smelting capacity was increased 1.6 times, from 800 tpd to 1,280 tpd using 33% oxygen-enriched air, and reaching an operative availability of 97%. By the other hand its campaigns have reached a record duration of 530 days without hot patching tuyeres and a partial refractory lining repair in the last four campaigns. This paper describes the most relevant improvements, as well as the strategies that had been used to reach these achievements.

Jan 1, 2007

By R. M. Lamya

The leaching behaviour of nickel?copper matte in an acidic?copper sulphate solution during the repulping stage at Impala Platinum Refineries has been studied. The base metal recovery process consists of a matte repulping stage prior to a series of pressure leach stages. Therefore, the repulping stage is basically an atmospheric leach stage in which the matte containing mostly Niand Cu is leached in copper-spent electrolyte from the tank house, resulting in dissolution of nickel and precipitation of almost all the copper. To understand the nature of the leaching process during this stage of the operation, the effects of temperature stirring rate and matte particle size on the rate and extent of base metal dissolution and copper rejection from the solution have been investigated. The leaching mechanism of the matte in the investigated system is alsoproposed.

Jan 1, 2006

By M. A. Islam, H. Mischo, G. Barakos

Among the thirty-five declared critical raw materials (CRM) in the United States, there is no sustainable domestic production for the fourteen of them, while for some others domestic supply does not meet the national demand. Numerous potential critical raw material projects are in advanced exploration stages. However, the price uncertainties for many of these commodities put feasible future production into question and come into contrast with overly optimistic price forecasts published in all feasibility studies related to such exploration projects. Thus, in this work, a newly developed smart computational tool is used to evaluate the real perspectives of several CRM exploration projects implementing actual commodity prices, and to conduct reverse calculations in order to find the prices at which each project can be viable.

Mar 2, 2022

By John Smyth

Mining through in panel entries and the full face recovery method has been successfully practiced at U.S. Stwl, Mine 50. Suppat of the cut-through entries and recovery room is critical. Traditionally, concrete crib or fly ash cement backfill has been utilized. However, these traditional methods are not feasible at Mine 50 due to the difficulties of the plow face mining through these types of support. Recent development of new cable support systems provides an option for cut-through entry support. Mine 50 and Jennmar Corporation personnel have worked together to design and apply the cable systems in the cut-through entries and full face recovery room to eliminate standing support. To date, a number of full face recovery rooms and cut-through inpanel entries have been successfully mined. The results indicate that the cable systems combined with high capacity shields, have provided sufficient capacity to support the roof. Utilizing the Jennmar Finite Element Analysis (JFEA) computer program (Stankus and Guo, 1996), an analysis of the stress and roof deflection changes as the longwall gradually cut through was conducted. From the finite element analysis data, a supplemental support plan was designed. The history and experiences at Mine 50 are presented. Based on the case experiences and modifications made to the finite element analysis, an improved design criteria for future use has been formulated.

Jan 1, 1998

By G. C. Baker

Despite the attention belatedly bestowed on tidal power in recent years, it remains largely a potential rather than an actual source of energy. The resource is, practically speaking, non-depletable. Extraction is technically feasible and environmentally acceptable. The restraints against development are economic, and they could be removed by technical improvements, changes in the cost or availability of other energy sources, or simply by a change in the cost of money. The exponential rise in the demand for energy makes it inevitable that the tides will be harnessed sooner or later.

Jan 1, 1972

By D. Nyungu

Despite observations of spalling and damage of mine excavation wall rock in the Bushveld Complex (BC) over the passage of time, there have been very few time-dependent or creep tests carried out in South Africa on rock, particularly on BC rock types. The research described in this paper deals with the investigation of stress and strain conditions influencing spalling of wall rock in BC mine excavations, and the influence of time on the tensile strength of several BC rock types. Time-dependent laboratory testing of BC rocks was carried out in indirect tension. The results show that the magnitude of the tensile strength of BC rock types is approximately 5% of their uniaxial compressive strength magnitudes. The average long-term uniaxial compressive strength of the BC rocks, interpreted from the axial stress-volumetric strain graphs, is 56% of the UCS value. The long-term tensile strength is shown to be less than 70% of the normal tensile strength. Extension strains at tensile strength failure ranged between 0.16 and 0.21 millistrain. Values corresponding with the long-term tensile strength are less than 70% of this range, namely, 0.11 to 0.15 millistrain. These results represent new knowledge, since such rock testing and analysis does not appear to have been carried out previously on BC rock types. Elastic numerical modelling was carried out to illustrate the extents of tensile stress zones and extension zones around of typical BC mine excavations. The models showed that large zones of extension strain can occur around BC excavations, and that the magnitudes of the extension strain can substantially exceed the critical values determined from the laboratory testing. The implication of this is that there are substantial zones surrounding BC mine excavations that will be prone to time-dependent spalling conditions and perhaps more significant failure.

Jan 1, 2014

By K. Ding

The thermodynamic activity of MnO was measured in MnO-CaO-MgO-SiO2 slags that are typically encountered in the production of manganese-containing stainless steels. A gas equilibration-quenching technique was employed in measuring the activities. Activities of Mn in Pt-Mn alloys were redetermined at 1600ºC, which reconfirmed earlier results of strong negative deviations. MnO activities were then measured by equilibrating slags of various compositions based on a statistical experimental design procedure with Pt-Mn alloys under controlled partial pressure of oxygen in MnO saturated platinum crucibles at 1600ºC. Activities of MnO were found to increase with increasing concentration of MnO, basicity and CaO to MgO ratio. Two multi-coefficient regression models were developed to predict the activities and activity coefficients of MnO in slags at 1600ºC. Keywords: activity, MnO, slag

Jan 1, 2005

By A. D. S. Gillies

Diesel engine particulate matter pollution is a matter of concern currently in underground mines worldwide. A number of real-time Diesel Particulate Matter (DPM) monitors have been developed in recent years; two of these by the National Institute of Occupational Health and Safety (NIOSH) in the US. One, the D-PDM, is based on an adaption of the successful NIOSH?s Personal Dust Monitor (PDM) unit which is being taken up very successfully for mine respirable dust monitoring. The D-PDM measures all particulate matter within a sub-micron range as classified nominally at 0.8 micrometers by a purpose developed cyclone. The other, the FLIR Airtec, measures the Elemental Carbon (EC) component of DPM by a laser scattering approach. Both instruments have been evaluated underground in robustness and reliability testing in coal mines by the authors. Real time DPM monitors allow greater understanding of the sources and levels of DPM pollution in underground activities. They allow engineering evaluations to determine how conditions can be improved or mining personnel relocated to lower concentration levels. Studies are discussed that examine DPM concentrations from vehicles under varying ventilation conditions. Some of these concern tests undertaken during high activity longwall face moves. They focus on evaluating DPM during the various phases of the face Chock Shield moves. An initiative in some mines has been to limit the number of vehicles in the mining section or panel by the use of a Tag Board or Traffic Controller at the panel travel road entrance to manage exhaust DPM and gases. Diesel tags or tokens are used to control the number of vehicles entering a section or panel and so limit level of pollution. Summation of DPM levels from points monitored throughout a panel demonstrates increasing DPM levels from influence of additional equipment in series within the ventilation circuit. An alternative approach is to invest in underground continuous real-time monitoring of exhaust gases, DPM and section air quantity and integrate this information to determine whether an additional vehicle can enter without exceeding diesel target limit. This optimizes the access of diesel vehicles and replaces the existing manual tag board system. Real-time DPM monitoring allows the industry to pin-point high exposure zones such as those encountered where various vehicles work in areas of constrained or difficult ventilation. Identification of high DPM zones allows efficient modification of mine ventilation, operator positioning and other work practices to reduce underground miners? exposures.

Jan 1, 2012

By E. Machaka, A. Cornah

"Mineral resources are typically informed by multiple data sources of varying reliability throughout a mining project life cycle. Abundant data which are imprecise or biased or both (‘secondary data’) are often excluded from mineral resource estimations (the ‘base case’) under an intuitive, but usually untested, assumption that this data may reduce the estimation precision, bias the estimate, or both.This paper demonstrates that the assumption is often wasteful and realized only if the secondary data are naively integrated into the estimation. A number of specialized geostatistical tools are available to extract maximum value from secondary information which are imprecise or biased or both; this paper evaluates cokriging (CK), multicollocated cokriging (MCCK), and ordinary kriging with variance of measurement error (OKVME).Where abundant imprecise but unbiased secondary data are available, integration using OKVME is recommended. This re-appropriates kriging weights from less precise to more precise data locations, improving the estimation precision compared to the base case and to Ordinary Kriging (OK) of a pooled data-set. If abundant secondary data are biased and imprecise, integration through CK is recommended as the biased data are zero-sum weighted. CK consequently provides an unbiased estimate with some improvement in estimation precision compared to the base case."

Jan 1, 2015

By Jennifer Pell

Dunsmuir Ventures? Nanuq diamond project is located approximately 250 km northeast of Baker Lake and 170 km north of Chesterfield Inlet. It occurs at the intersection of the Wager Bay shear zone with the Keewatin Arch, a major long-lived crustal uplift. The newly discovered diamondiferous kimberlites at Rankin Inlet, Repulse Bay and on Melville Peninsula also occur along this arch. Kimberlite indicator mineral (KIM) sampling has outlined a distinct KIM train more than 35 km long and 6 km wide. Geomorphological studies, boulder displacements and dispersion of magnetite in tills suggest that glacial transport distances were on the order of 4 to 6 kms only. The presence of multiple sources within the main Nanuq indicator train would account for its length and breadth. A second train has been located on the west central part of the property and anomalous concentrations of KIM occur elsewhere. Pyrope garnets (G9?s and G10?s), diamond inclusion field (DI) eclogitic garnets and DI chromites were confirmed by microprobe analyses. Clinopyroxene thermobarometry indicates a cool geotherm, approximately 35 mW/m2, and that mantle within the diamond stability field was tapped. An aeromagnetic survey has identified a number of anomalies. Those with down ice KIM support will have ground geophysical follow-up and will be tested in a spring 2004 drill program. Dunsmuir is optimistic that this will lead to the discovery of a new kimberlite cluster on the Nanuq property.

May 1, 2004

By Rocky (Yaokun) Wu

This paper introduces the development and application of a new cable anchor - Cable-Lok for pre-stressed cable bolting in mines. Cable-Lok is a spring-loaded cable anchor suitable for the drill hole diameter of 50 and 65 mm (2" and 2.5") in medium soft rock to hard rocks. The cable anchor is automatically set on installation and the cable can be tensioned immediately to provide active and primary support throughout its length. Post-grouting can be conducted independently. In comparison with the conventional cable bolting, Cable-Lok anchor will greatly speed-up the cable bolting circle and decreases the cost of cable bolting. Cable bolting anchored with Cable-Lok anchor has wide application in mines, e.g. pre-stressed cable bolting in large span drifts and intersections for permanent rock support, or in hanging walls or stopes for temporary support, or cable lace anchoring etc. This paper introduces the principle of pre-stressed cable bolting and the specifications of the Cable-Lok anchor, presented the testing results in laboratory and the application cases in mines.

Oct 1, 2010

By J Temos

This paper outlines a number of immediate practical approaches to continuous improvement in environmental management in the minerals industry. It puts these into context with longer time-frame step-change approaches whose gestation may take a decade. Examples of improvements and approaches are drawn from WMC operations.

Jan 1, 2002