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By Laurens de Jonge, Wiebe Boomsma, Rodney Norman, Stanislav Verichev

"Earth provides natural resources, such as fossil fuels and minerals that are vital for human life. As the global demand grows, especially for strategic minerals, commodity prices rapidly rise. Thus there is an identifiable risk of increasing supply shortage for minerals. Hence a major element in a long-term economic strategy must be, to ensure security of supply for these strategic minerals. In this rapidly changing global economic landscape, deep sea mining has gone from a distant possibility to a likely reality within just a decade.Although deep sea minerals extraction was investigated in the 1970’s, it was abandoned because of changing commodity economics, advances in on-land exploration techniques, growing concern on environmental impact, and political and legal aspects with regard to ownership issues. The developmental data from those days, if still available, are not adequate to allow engineering and building of an integral system for extraction of deep sea minerals without additional R&D work. Thus, deep sea mining is yet to attain a Technology Readiness Level (TRL) sufficient to successfully undertake deep sea mining operations, from resource discovery to resource assessment and to resource exploitation [Blue Mining, 2014]."

Sep 1, 2014

Site specific geotechnical data, deposit characteristics and method of mining are key factors when assessing an appropriate slope design philosophy. Mining geotechnics should be viewed as an iterative design process linked closely with mine planning, development and operational safety constraints. This case study presents geotechnical investigations for slope design at Macraes Flat Gold Mine using kinematic, probabilistic and economic analyses tempered with knowledge of site specific conditions. The recommended designs not only reduce early waste stripping tonnages but also provide data to optimise final walls.

Jan 1, 1992

By Chu E. Ho

Current methods of determining jet grout column diameters are highly empirical and site specific, and do not take into account the jet hydrodynamics and soil parameters explicitly. A theoretical model which describes the jet excavation mechanism is introduced in this paper, with the aim of providing an improved prediction tool that can be used in jetting design. The model is based on the assumption that the velocity distribution in the cutting jet is equivalent to that of a free jet with boundaries corresponding to the dimensions of the cavity excavated in the ground. The shape of the cavity formed depends on the erosional properties of the soil and jet expansion is limited by the resistance at the jet-soil interface. The model predicts that the limit of jet penetration is reached when the average dynamic pressure at the jet tip becomes equal to the ultimate soil bearing resistance. The reliability of the model, evaluated using results from four case histories of jet grouting field trials, is within ±15%.

Jan 1, 2006

By K. Burke, G. Zhan, A. Mayer

A cover with capillary barrier effects (CCBE) is being constructed on the AA Leach Pad at the Barrick Goldstrike Mine site near Carlin, Nevada. The purpose of the cover is to eliminate/minimize infiltration of meteoric waters into the leach pad. Laboratory and numerical analyses indicate that Carlin Formation siltstone (TCS), a locally available material, has the necessary hydrologic characteristics when placed on the leach pad to act as a CCBE. A pilot study has been conducted on a small-scale test cover placed on the AA Leach Pad to examine the cover performance under irrigated conditions. The preliminary test results demonstrate that the designed cover is capable of preventing meteoric water infiltration.

Jan 1, 2001

By Ketan H. Trivedi

This paper describes the method of analyses used for the design of temporary and permanent Secant Pile Walls, describes various aspects of construction including, guide walls, sequence of pile installation, plan alignment and verticality tolerance, methods of drilling (auger, wash boring, cased and open holes), lateral bracing for secant piles, cutting of keys in secant pile walls for the connection of permanent floor slabs, sealing of water leaks and waterproofing. The paper concludes with a brief case history of a secant pile wall project recently constructed in New York City.

Jan 1, 2006

By J. E. Nesset, F. Rosenblum, J. A. Finch

"The self-heating of sulphides can be a major hazard in mining operations and concentrate handling, particularly during transportation and associated storage. Self-heating results from the oxidation of sulphide minerals and can vary from being insignificant to highly reactive and potentially hazardous to both humans and infrastructure. It is essential that there be a reliable test methodology that can measure and categorize a given sulphide material as to its self-heating potential. By their nature, sulphide ores and concentrates are complex and variable mineral mixtures making it difficult to predict their self-heating behaviour a-priori based on mineralogy or with a simple “snapshot” test. Furthermore, self-heating behaviour will depend on the state of oxidation of the sulphides as well as time, temperature and humidity. A review of available testing apparatuses and protocols that can be used to assess self-heating potential is presented. Each of these methodologies was examined in relation to its ability to measure and reliably predict the latent self-heating hazard of a sulphide material. Several of the methods were tested and compared to illustrate their strengths and weakness. The results indicated that a number of the test protocols may produce false negative indications of self-heating potential, constituting an obvious concern to the industry.INTRODUCTION Sulphides as well as other materials (coal, wood chips, hay, powdered milk, to name a few) that are stockpiled in an air atmosphere may undergo oxidation reactions which can result in the evolution of heat (Beever, 1984) (Hudak, 2002) (Blanchard, 2007). If the rate of heat generated exceeds the rate of heat dissipation, the stockpile temperature will rise, potentially leading to “hot spots” in the most reactive areas, and possibly even fires. The heat generation rate, the “self-heating” rate, depends on many factors such as the type and composition of material, particle size, moisture content, oxygen availability, ambient temperature and humidity, and of prime importance, the extend of prior oxidation, or more specifically, the presence of oxidation products. The desire of operators that mine, process or transport sulphide-bearing materials with a potential for self-heating is to have an accepted and reliable method for evaluating and quantifying the potential hazard of their material. The challenges are how to best measure the self-heating properties of given samples, and based on results, predict the behaviour of the bulk material over time and in-situ. Generally, when evaluating a given material one derives the self-heating characteristics of that sample at the time and under the conditions of testing, which will be referred to as a “snapshot test”. If that material is invariable, i.e. it will not change its response over time, then it may be considered to be a “predictive test”. However, if as a result of continuing oxidation or other changes, the material becomes more or less reactive with time, then a “snapshot test” is unreliable with respect to predictive ability."

Jan 1, 2014

By Charles L. Kusik

As part of an effort to establish the extent of the domestic chromium supply that could be exploited in case of adverse changes in international chromium production and trading patterns, a two-part study was conducted for the Bureau of Mines, to assess the domestic availability of critical metals in scrap containing significant amounts of chromium. This report describes the part of the study that deals with wrought stainless steels and heat-resisting alloys. Data were collected on types of scrap, sources, quantities, and ultimate disposition, leading to the conclusion that In 1917 about 62,000 tons of contained chromium was unrecycled. Unrecovered obsolete stainless steel scrap accounts for most of these uncollected chromium values. Error margins in the amount of uncollected scrap are estimated to be 10 to 20 percent.

Jan 1, 1980

By R. Katzenbach, M. Vogler, U. Adamietz

Abstract The design of deep excavation pits in rock mass is dependent as well on the mechanical properties of the rock mass as for example the orientation and the type of discontinuities like bedding planes, joints and fissures, the length of the discontinuities (persistence), the grade of weathering, the strength of rock mass, and the shear strength in the discontinuities, etc., and also on the respective boundary conditions specific for the project, and here especially the geometrical boundary conditions. The basic mutual influences and interactions between these boundary conditions are explained and exemplary presented at an excavation pit with a depth of 18,5 m, situated at a slope with a surface near groundwater table. Résumé La planification des excavations profondes dépend aussi bien de la qualité mécanique du roc, par exemple la location de la texture de la surface de moindre résistance, le degré de rupture, le degré de décomposition, la dureté du roc et la résistance limitée au cisaillement de la texture de la surface de moindre résistance que des conditions limitées spécifiques pour le projet, ici en particulier des conditions limitées géométriques. Les influences et interactions essentielles et mutuelles entre les conditions limitées isolées seront expliquées et présentées à l’aide d’une excavation 18,5 m de profondeur, située sur une pente où le niveau des eaux souterraines est près de la surface. Kurzfassung Die Planung tiefer Baugruben im Fels hängt sowohl von den mechanischen Eigenschaften des Fels wie z.B. der räumlichen Lage des Trennflächengefüges, dem Durchtrennungsgrad, dem Verwitterungsgrad, der Gesteinsfestigkeit sowie der Scherfestigkeit des Trennflächengefüges als auch von den projektspezifischen Randbedingungen hier insbesondere von den geometrischen Randbedingungen ab. Die wesentlichen gegenseitigen Einflüsse und Interaktionen zwischen den einzelnen Randbedingungen werden aufgezeigt und an einer 18,5 m tiefen Baugrube in Hanglage mit oberflächennahem Grundwasser vorgestellt.

Jan 1, 2003

By Mohammed Sakr

The use of helical piles for permanent foundation applications has become a practical and feasible alternative to the traditional cast-in-place concrete or driven steel piles. Research and development, installation equipment and manufacturing improvements in the helical piling industry have led to this trend. Moreover helical piles are typically smaller in size and weigh less than traditional piles, and require relatively smaller equipment and therefore it is a cost effective option. The latter is a very attractive feature for foundations installed in remote sites across Alaska. This paper presents full-scale pile load test results of helical piles and driven steel pipe piles installed in a site located in Anchorage, Alaska. Four full-scale pile load tests were carried out including two axial compression and two uplift load tests. Both helical piles and driven steel pipe piles were installed and tested at the same site under similar conditions to provide a direct comparison. The results of the full-scale load tests indicate the superior performance of helical piles compared to driven steel pipe piles. This paper describes the pile installation and test setup, presents the test data, and discusses the results.

Jan 1, 2009

During the drilling campaign conducted between October, 1942; and May, 1943, to prove the extent of the scheelite deposit worked by King Island Scheelite N.L. at Grassy, King Island, Tasmania, 35 holes were drilled and 606 samples recovered and assayed for their content. Of these, 238 came from outside the limits of the orebody and were for the most part barren, although a few contained some scheelite. The present statistical analysis is made only of the 368 samples taken from diamond-drill cores of the orebody itself.Drilling Pattern and Sampling MethodsFrom the purely statistical viewpoint, it is realised that methods employed in selecting sites for diamong.-drilling, and of collecting samples from drill cores, do not give a completely unbiassed set of data for analysis. Fig. 1 is a sketch plan showing the relativepositions of the drillholes, which were inclined at an angle of depression of 50 deg. The pattern does not conform to a properly randomized and' regularly-spaced grid, the positions of the later holes being determined by the results obtained from previous holes.Statistically, the bias is, therefore, favourable. The unequal spacing of the drill holes and the lack of uniformity in direction of the lines along which the holes were drilled are unsatisfactory from the mathematical viewpoint; but it is realised that these irregularitiesare difficult to avoid in determining by the most economical methods the extent of such an orebody, and are dictated by geological rather than mathematical necessity.Sampling, also, is lacking in complete uniformity. Each sample is approximately 10ft. in length. However, owing to the fact that 100% recovery of core is rarely achieved, and actual lengths of samples taken are ,primarily governed by the length of the drill runs,and secondarily by lithological changes, there is a considerable amount of variation in the sample length.AssayingWith the exception of 28 samples from three drill holes all samples dealt with in this paper were assayed in the Melbourne University Ore-Dressing Laboratory of the Commonwealth Scientific and Industrial Research Organisation. These assays were given to the nearest 0.05% WOg as it was considered that more accurate determination was not possible. This fact has been taken into consideration in the frequency analysis below. The 28 assays determined by the Tasmanian Mines Department were given to the nearest 0.01%.

Jan 1, 1950

By Wood W, Bell A

Brown coal production in Victoria's Latrobe Valley Region (Figure 1) continues to rise and currently stands at around 50 Mt per annum. With the exception of around 2 Mt used to produce some 700 Kt of brown coal briquettes, this coal is mined by the State Electricity Commission to fuel large thermal power stations with a total installed capacity of just over 5 000 Megawatts. The moisture content of the coal as mined typically exceeds 60 per cent, making Latrobe Valley coal a markedly low rank fuel. The lack of heating value is, however, compensated for through power station design and by the fact that ash yield is very low, usually within the range of one per cent to four per cent on a dry basis. This means that compared with most other coals, the burning of Latrobe Valley brown coal produces relatively small quantities of waste products and discharges a minimal level of pollutants into the atmosphere. Even so, the inherent quality of Latrobe Valley coal does vary significantly from one area to another (Gloe, 1991; Barton et al, 1992) both on a local and a regional scale. Such variations need to be recognised and understood in order to not only realise efficiency gains in existing power stations but to properly assess resource potential for future utilisation and the application of new technologies. The principal aim of this paper is not to describe coal quality variation in detail or to speculate on the nature of and reasons for such variation. Rather, it is to simply underscore that significant differences do occur and that this is clearly a factor which needs to be considered in any evaluation of Latrobe Valley brown coal as a resource for the future.

Jan 1, 1992

By Gerry Houlahan

The east span of the 3.5 km long SF-Oakland Bay Bridge is supported by different types of foundations along its span. Starting from the west, its first 460 m section comprising twin concrete box-girders is supported by sands and rock on Yerba Buena Island. A 620 m long steel suspension span then bridges a 25 m deep channel that is formed in sediments overlying rock. Twin concrete box girder structures, each 2.4 km long, complete the stretch over the remainder of San Francisco Bay to the engineered earth fill landing at its east end. For most of its length, the Skyway bridges water 3 to 10 m deep over soft surficial Young Bay Mud. The foundation types include spread footings with hold-downs, steel and concrete piles that are set in drilled rock sockets up to 3 m in diameter and 2.5 m diameter steel tubular piles driven to penetrations of up to 100 m. The design and construction-related considerations are presented. The different foundation types, influences of the site geology and earthquake demands on the substructures are discussed. The seismic motions of the bridge superstructures and substructures, as well as the depth-varying soil motions, influenced the foundation design. Together with performance-based design criteria, including post-earthquake footing displacement limits, these seismic demands influenced various aspects of the foundation design, including the use of battered and vertical piles.

Jan 1, 2005

By G. R. Morin, A. R. Leggett

"In 2010, closure of the Kidd metallurgical plants along with structural changes to the historical ratios of payable metals led to a review of the operating targets at the Kidd concentrator. Previous operating data indicated that there was potential for significant revenue improvements by lowering the copper concentrate grade. An extended plant trial was carried out in 2011 to quantify the revenue impact of lowering the copper concentrate grade from 27% to 25% Cu, as well as identifying the lower practical grade limit. Analysis of plant trial results indicated that the process change increased net concentrate revenue by $2 M to $3 M per year at current metal prices. Increased revenue was primarily associated with higher silver recovery to the copper concentrate while the marginally improved copper recovery was essentially offset by increased zinc losses and concentrate treatment and freight charges.Details of the plant test work results are discussed in this paper along with the financial analysis of the revenue improvements. Key areas covered are major revenue components of the concentrate contracts, validation of revenue improvements through plant testing and sensitivity of the improvements to market and plant variables.INTRODUCTIONThe Xstrata Copper Kidd concentrator commenced operations in 1966 treating ore from the nearby Kidd volcanogenic massive sulphide deposit in Timmins, Ontario (Thompson, Amsden, & Chapman, 1978). Over the years, up to four separate grinding-flotation divisions were in operation with throughput rates peaking at 4.5 million tonnes per year of ore in the mid 1980’s (Kelebek & Francis, 1998). As the mine production decreased and grinding throughput increased operations were gradually cut back and since 1998 two grinding-flotation divisions have been in operation treating Kidd mine ore. One of the idled divisions has been intermittently used for custom milling operations, most recently the Ni/Cu Montcalm deposit, which was milled from 2004 to 2009. Current budget throughput rates, limited by mine production, are 2.4 million tonnes per year of ore grading 1.7% Cu, 4.3% Zn and 55 g/mt Ag. Concentrate production rates are 150,000 tonnes per year of copper concentrate and 155,000 tonnes per year of zinc concentrate. The Kidd mine is the deepest base metal mine in the world with mining operations down to 9600 ft.In 2010 the copper and zinc plants at the Kidd metallurgical site, which previously treated the concentrate production from the Kidd concentrator, ceased operation due to a variety of economic and market factors. Following the metallurgical plant closures the Kidd concentrator products were shipped off site for treatment. The majority of the copper concentrate is now processed at the Xstrata Copper Horne smelter in Rouyn-Noranda, Quebec with the majority of the zinc concentrate processed at Canadian Electrolytic Zinc Ltd. in Valleyfield, Quebec."

Jan 1, 2013

By Rao Balusu, Bharath Belle, Krishna Tanguturi

A collaborative research project is undertaken by Anglo American Coal and CSIRO to develop appropriate strategies for gas and spontaneous combustion management of longer panels. Extensive computational fluid dynamics (CFD) modelling studies have been conducted and calibrated using operational longwall goaf gas data to obtain a fundamental understanding of goaf gas flow patterns in longwall panels of 1.0-km and 3.0-km lengths and a detailed investigation of the effect of various mining and operational parameters on goaf gas flow patterns. The modelling studies have also been used to investigate the performance of various gas drainage and proactive inertisation strategies during various stages of longwall panel extraction. Simulation results indicated that apart from tailgate (TG) side goaf holes, gas drainage from maingate (MG) goaf holes and the mid panel start-up goaf holes would be useful for flat seam field conditions. Operation of 8–10 goaf holes is recommended for field site conditions with high goaf gas emissions of 6000 L/s. The modelling results indicated that the traditional inert gas flow rate of 500 L/s currently used in some mines would be insufficient to achieve effective goaf inertisation in long panels. Results indicate that 3.0- km-long panels would require 1500 L/s of inert gas and there is a need for multi-point inert gas injection strategy for effective goaf inertisation. In this paper, details and results of modelling investigations and recommended strategies for gas and spontaneous combustion management in 1.0-km- and 3.0-km-long panels are presented.

By Rao Balusu, Bharath Belle, Krishna Tanguturi

A collaborative research project is undertaken by Anglo American Coal and CSIRO to develop appropriate strategies for gas and spontaneous combustion management of longer panels. Extensive computational fluid dynamics (CFD) modelling studies have been conducted and calibrated using operational longwall goaf gas data to obtain a fundamental understanding of goaf gas flow patterns in longwall panels of 1.0-km and 3.0-km lengths and a detailed investigation of the effect of various mining and operational parameters on goaf gas flow patterns. The modelling studies have also been used to investigate the performance of various gas drainage and proactive inertisation strategies during various stages of longwall panel extraction. Simulation results indicated that apart from tailgate (TG) side goaf holes, gas drainage from maingate (MG) goaf holes and the mid panel start-up goaf holes would be useful for flat seam field conditions. Operation of 8–10 goaf holes is recommended for field site conditions with high goaf gas emissions of 6000 L/s. The modelling results indicated that the traditional inert gas flow rate of 500 L/s currently used in some mines would be insufficient to achieve effective goaf inertisation in long panels. Results indicate that 3.0- km-long panels would require 1500 L/s of inert gas and there is a need for multi-point inert gas injection strategy for effective goaf inertisation. In this paper, details and results of modelling investigations and recommended strategies for gas and spontaneous combustion management in 1.0-km- and 3.0-km-long panels are presented.

By Claudio Olalla

This paper relates to the foundation of a steel structure located at the San Martin de la Vega (Madrid) amusement park. The structure has more than 100 supports with various loading conditions, including important horizontal and uplift forces. Additionally, the settlement tolerances are very strict. A massive gypsum formation with interbedded clay layers and random solution great voids at various levels constitute the soil. The foundation design has been conditioned large enough these difficulties (load conditions and soil problems). The piling machine used was powerful to drill through the soft rock (UCS up to 11Mpa). The integrity of each pile had to be guaranteed by continuous recording of drilling and concrete pouring parameters. In order to fulfil all those conditions, a STARSOL type-piling rig was used. More than 4500 meters of piles were performed. The diameters of the piles were 450 and 550-mm and their depths varies from 6 to 23 meters. All piles were reinforced over their full length.

Jan 1, 2002

By R. C. Earlougher

Jan 1, 1970

By Howard A. Perko, M. Mae Benvenga, Heather H. Trantham

Displacement of soil and groundwater during helical pile installation can produce excess pore water pressures (PWP) in fine-grained soils. Pore water pressure reduces effective stress in the soil immediately adjacent to the helical pile shaft and near the helical piles. Previous studies have shown generation of PWP may affect the capacity to torque ratios of the helical bearing elements. Large diameter helical piles that generate much of their torque and capacity from shaft adhesion are affected by PWP and therefore exhibit significant pile "freeze" after installation. Computer modeling is used herein to evaluate PWP immediately adjacent to helical pile shafts during installation in various soil types. The models show the degree and distance from the shaft that is influenced by PWP during installation and the amount of time required for the PWP to dissipate. Pile freeze has been measured on several project sites by re‐torque measurements. These re-torque data are compared with computer modeling and correlations between saturated hydraulic conductivity and dissipation time are presented and discussed. INTRODUCTION Helical piles are full-displacement piles, meaning installation does not produce drill spoil. Soil is displaced laterally as the pile progresses into the ground. This displacement of soil causes an increase in PWP, which reduces adhesion between the pile and the soil. For helical piles with small-diameter shafts, adhesion contributes little to the overall capacity and torque of the pile, so PWP changes are not typically considered in determining pile capacity. In modern construction, the use of larger diameter helical piles has become very common. For large-diameter helical piles, changes in PWP immediately adjacent the shaft can be quite large during installation. Increased pore water pressure and reduced adhesion can have a temporary effect on pile capacity and installation torque.

Jan 1, 2018

By Ulf G. Gwildis

The Bright water Conveyance System includes 21 km of tunnels mined by two earth pressure balance Tunnel Boring Machines (TBMs) and two slurry TBMs. The probabilistic baseline approach defined in the Geotechnical Baseline Report (GBR) can representatively be verified by use of a comprehensive tracking system to identify face conditions that allows comparison with the baselines. The glacial geology includes a high lateral variation in soil types that, when combined with the pressurized face tunneling methods, creates challenges for documenting face conditions. Baseline tracking using spoil samples and TBM operational parameters provides information to document actual conditions and support resolution of differing site condition claims.

With the proving of a mineable orebody at Orlando in May 1961, Peko Mines N.L. was faced with the decision of whether to mill the ore on site or to haul it 25 miles to central facilities at Peko. Orlando was a relatively small orebody, so that it was decided to haul, although no reliable assessment of possible ore haulage costs was available.The necessity for a good haul road was recognised from the beginning and a 17 mile, 12 ft wide, single seal bitumen road was constructed, to link the mine to the Stuart Highway and Peko. The initial selection of 20 ton capacity diesel-powered end-tipping ore carts was made, with the best information available at the time.Since then some 130,000 tons of ore have been carted over a period of 3 years, and this paper presents the experiences of this haulage operation and the lessons learned.A second mine has just been brought into operation at Ivanhoe, 19 miles from Peko. For this haul it was decided to use an ore haulage vehicle of the side tipping road train type, which would cart some 70 tons, or more than three times the load of the vehicles initially selected.Only about 5,000 tons had been hauled at the date of this paper, but preliminary figures indicate a cost 01 1· 65d./ton-mile as against 2·47d. for the smaller vehicles.It would appear that the road haulage of ore from small outlying mines to a central plant can be highly economical, if certain basic rules concerning haul roads and vehicle selection are followed. This paper does not try to determine the maximum tonnages and haul distances which would finally make road hauling uneconomical...

Jan 1, 1966