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By Paola Campana, Maurizio Lenzi

"In the paper a non linear model for the analysis of the pile response to the axial loads is presented. The study aims to find a general analytical solution concerning the pile-soil interaction modeled by means of the method of the load transfer curves. It makes use of a criterion based on the plastic and on the hardening work locally done by the shear stresses and due to the current elastic shortening of the shaft. Then a specific solution, denoted fractal model, is found applying recurrent relations that link the shaft shear stresses and the tip normal stresses to the pile settlements. These relations are based on that one proposed by Kondner in modeling the soil samples response in the triaxial tests and then used by Chin in the inverse slope method in estimating the pile capacity by the load test results. The comparison between the model predictions and the load tests measures validate the fractal model.INTRODUCTIONThe behavior of the axially loaded piles is known to be characterized by a highly non linear trend caused by the onset of plastic and irreversible deformations in the soil starting just from the first load levels. With the purpose to reach a deeper understanding of the pile-soil interaction, the influence of the soil inelastic properties on the distribution of the axial loads and of the vertical displacements is investigated. The research starts analyzing the behavior of an infinitesimal length of a pile embedded in a non linear homogeneous soil. That initial study leads to a criterion based on the plastic and on the hardening work locally done by the shear stresses and that allows to find the axial loads as a function of the elastic shortenings of the shaft. The relation that links the pile axial load to the elastic strain of the pile material is then used. That allows to find the vertical displacements and the axial loads as function of the depth in a parametric form in which the tip settlement acts as an independent parameter. The method of the load transfer curves is used and the effects of the pile technology are included in the soil constitutive relations. The analysis is then extended to the non-homogenous soils in a very effective way. The solution is applied taking as constitutive relations of the pile-soil interface the one proposed by Kondner to analyze the soil triaxial tests and by Chin to interpolate the pile response measured in the load tests."

Jan 1, 2017

By B. J. Beaudry

The preparation of alloys containing one to two percent of the volatile lanthanide metals Sm, Eu, Tm and Yb in the high melting point (HMP) rare earth metals Sc, Y and Lu was accomplished by a vapor deposition, diffusion method without crucible contamination. The method avoids the melting of the HMP metals which would introduce impurities from the crucible, generally Ta or W. Plates of the HMP metals were hung from the lid in the upper part of the Ta crucible. The volatile metals were placed on the bottom and the lid welded in place under an atmosphere of helium. By proper selection of thee alloying temperature, the effusion of the metal vapors, through the helium atmosphere was slow enough to permit diffusion to occur and prevent refluxing of the newly formed alloy. Very volatile metals such as Mg required a Knudsen cell with a suitably sized hole to prevent too rapid transfer of the low melting metal. Electron microprobe analysis of a cross-section of the HMP metals showed a homogeneous distribution of the volatile metals. The time and temperature required to obtain a homogeneous rare earth alloy without contamination are given. The use of a Knudsen cell to form magnesium-rare earth alloys is reviewed.

Jan 1, 1992

By B Jones, M Chappell

Installing ground support correctly is not an easy task, whether lack of operator training, poor ground conditions or underperforming equipment. Confirming the quality of installation can help with planning and remedial works and help to maintain a safe working environment. A 2?m bolt with 700?mm of encapsulation will pass a 10?t pull test (assuming ground conditions permit); however, it will not provide any data of the unencapsulated length and thus the ability to withstand corrosion. Complimentary testing in the form of non-destructive testing (NDT) can provide factual data that leads to the assessment of the quality of the encapsulation. By improving the quality of the encapsulation, the risk of corrosion is reduced, the ground support durability is improved and hence the asset life is enhanced.This paper presents a case study of a trial using the NDT system RokTel™. Installations of varying quality were installed and tested. The characteristics tested were corrosion, load and free length. These characteristics can be tested and assessed for cable bolts, thread bar bolts and split sets. The aim of this paper is to present NDT testing as a viable method for assessing installation quality and ongoing performance of the ground support.CITATION:Jones, B and Chappell, M, 2014. A non-destructive testing method for measuring bolt condition, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 307–314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

In mining industries, materials loading and handling costs represent a significant component of the total (capital and operation) costs. A variety of methods have been applied in surface mine equipment selection in order to select the suitable loading and haulage system with the lowest total cost. The optimal size and number of equipment calculation are very important task for mining engineering because loading and haulage equipment are major proportion of open pit mining cost. Capital and operating cost are considered in objective function with respect to interest rate, insurance and tax in non-linear form. Shovel and truck annual productivity constraint, fleet matching constraint and number of truck per shovel constraint are incorporated in this optimisation problem with continuous variables. This formulation will yield total cost minimisation per hour and good accuracy compared to previous methods.

Dec 6, 2010

By R. H. Batey

"The process control and cost of monitoring mining slurries is normally accomplished using a continuous mass flow system, conventionally embodying a volumetric magnetic flow meter and nuclear density meter. DuPont’s Maxville Mine at Starke, Florida, USA was chosen to examine costs associated with performance of a nuclear density meter. Since it is typical of many mid-sized establishments and has a long history in their use. The published accuracy under ideal conditions of a nuclear density meter is ± 1.0%, but in practice considerable ambiguity of cost in annual production implies ± 2% at best. Using such accuracy in a 400mm (16”) pipe carrying zircon slurry at 75,000 tons/day, the cost of ambiguity, together with initial and running costs, amount to nominally $962,000 per year.Such cost leaves much to be desired. This paper describes an unique continuous, direct mass per unit volume Density Meter used for mining slurries in pipe sizes up to 1000mm (40”), which significantly reduces the cost of ambiguity of measurement and running costs. At the same time the disadvantages of nuclear devices are obviated.In an effort to reduce costs, a 400mm non-nuclear Density Meter was installed at the DuPont Maxville mine. A typical on-site accuracy can be shown to be ± 0.285%, whereby the cost of ambiguity, initial and running costs in the example above shows an annual improvement of $78,660, a reduction of over $880,000 per year.Even higher cost savings may be demonstrated with mass flow systems having gas entrainment compensation. Unlike nuclear and other inferential density meters, the signal quality of this non-nuclear Density Meter is totally unaffected by entrained gas found in mining slurries. This non-nuclear density meter is then ideally used with a vortex velocity domain sonic flow meter, and provides for the first time compensation in wet density or dry % solids, as well as wet or dry mass flow of mining slurries with entrained gas, resulting in enormous reductions in cost ambiguity."

Jan 1, 2013

By A Melkumyan, F Ramos

This paper addresses the problem of prediction of grade variables over volumes (block estimation) for an autonomous mine. Resource estimation is usually concerned with the prediction of the quality of material over volumes (blocks in resource models). This problem is tackled by developing Bayesian block estimation with the Gaussian processes (GPs) framework. GPs are commonly used for nonparametric regression and classification and offer an elegant solution to deal with incomplete knowledge and information. A GP is defined by its mean and covariance function. The parameters of the covariance function can be learnt by maximising the marginal likelihood of the data. This offers a way of automating the covariance fitting process, while at the same time allowing for an assessment of how well the covariance function fits the data. Within the GP framework the calculation of the average grade over a volume can be performed using Bayesian quadrature, which treats an integral as a random variable. First, it is demonstrated that the block kriging equations in geostatistics are the same as Bayesian quadrature. Then, it is determined when closed form analytical solutions for the integrals are possible and quadrature approaches for approximations are briefly discussed.

Sep 26, 2011

By Ian Sheppard, Kugan Kuganathan

The Mount Isa Rocky Paste Fill (RPF) was one of the five fill options investigated for the Enterprise Mine filling between June 1996 and September 1996. Co-disposal of deslimed cemented tailings (CHF) and suitably graded rockfill (RF) in certain ratios produced the rocky paste fill. The RPF behaved like a cohesive paste with very high proportion of rockfill in the mix. Several large-scale mixing trials and drop tests proved that the rocky pastefill results in a homogeneous fill mass after placement. Segregation of RF was a common problem with MIM's traditional cemented rock fill (CRF), which is a combination of CHF and RF. The segregation was eliminated and a non-segregating paste like fill was created by optimising the particle size distribution of RF, and combining the RF and the CHF in optimum ratios. In rocky pastefill, the excess water in the cemented deslimed tailings slurry is taken up by the rockfill as the surface moisture on the rockfill particles and also as pore water between the particles. This results in thickening of the CHF, and the resultant mix is a non-segregating cohesive paste, which can easily spread to any horizontal distance inside a stope at a very low surface angle. The rocky pastefill releases no free water and relatively more pervious than the standard CHF due to rockfill component. With an average cement addition of 1.5 to 2% the rocky pastefill can develop higher strengths over 1Mpa. The rocky paste fill is applicable in many situations and can accommodate a variety of coarser materials that would be available in different mine sites. This paper present the research work and the experience associated with the rocky paste fill, and gives clear design principles for any potential users.

Jan 1, 2001

There are many compelling reasons why correct sampling schemes should be standard practice in the mining industry, yet there are numerous examples where poor sampling practices are known to exist in the business yet permitted to continue. It is not just technical issues that can be ascribed to the reasons for the continued use of incorrect methods. This paper proposes non-technical reasons why incorrect sampling practices continue, and identifies potential ways to overcome them.

Mar 1, 2010

By M. Cai

"It is well known that Peak Particle Velocity (PPV) plays a critical role in triggering rockburst damage in burst-prone underground mines. To estimate the PPV distribution around excavations, advanced numerical modeling can be used. In wave propagation numerical modeling, velocity field is often assumed to be uniform around an excavation. However, it is observed that wave velocities near mine openings are not constant, but rather non-uniform. Wave velocity in a rock mass depends on many factors such as rock quality and confinement. In particular, confinement has a large influence on wave velocity. The confinement around an excavation is low at the wall boundary and increases gradually and reaches a constant value far away from the excavation boundary. Hence, stress redistribution due to excavation will have a profound influence on wave propagation in underground mines. A better understanding of the influence of excavation effect on wave propagation helps to interpret the field observation of rockburst damage and improve mine safety. For this purpose, a non-uniform velocity model need to be constructed and the influence excavation effect should be taken into account in numerical wave propagation modeling.In the present study, a non-linear velocity model is developed firstly by considering the influence of confinement on wave velocity. This model links wave velocity to confinement explicitly. A coupled numerical method is then developed and used to study the seismic wave pattern around excavations in underground mines. Two codes, FLAC and SPECFEM2D, are coupled in the analysis. The motivation of developing the FLAC/SPECFEM2D coupled approach is to take merit of each code, such as the stress analysis capability in FLAC and the powerful wave propagation analysis capability in SPECFEM2D. The coupling process is realized through three steps: (1) static stress redistribution around an excavation is analyzed in FLAC; (2) data for coupling analysis, such as non-uniform velocity field (based on the new developed velocity model), mesh, absorbing boundaries, etc., are generated by FISH functions in FLAC and passed to SPECFEM2D; and (3) wave propagation modeling is performed in the SPECFEM2D considering a fault-slip seismic source. Because stress redistribution around the excavation is considered, non-uniform velocity field for the SPECFEM2D model can be obtained and this is a notable feature of this study. Very large difference in the S-wave response in these two modeling approaches with uniform and non-uniform velocity fields can be seen from the modeling results.Using the FLAC/SPECFEM2D coupled modeling approach, accurate velocity models can be constructed and this in turn will help to produce accurate PPV distribution around the excavations. Accurate PPV contours can be used to identify high rockburst risk zones for improved dynamic ground support strategy."

Jan 1, 2015

By H. Reginald Hardy, Xiaoqing Sun

Rheological models are widely accepted as a means of describing the mechanical behavior of geologic materials. It has been found, however, that rheological models developed for a specific stress level on the basis of linear visco-elasticity generally are not satisfactory at other stress levels. It has been suggested that the parameters of such models should be functions of stress level (Hardy, 1965; Kim, 1971). In this paper, continuous functions of stress have been utilized to obtain the required variation of Burgers model parameters with stress level. The model developed using these functions provides a constitutive relation which reflects the real time-dependent behavior of rock materials. The new model is capable of predicting the creep behavior over a wide range of stress levels and also predicts mechanical behavior under different loading condition (e.g. constant stress rate). It is also interesting to note that the mechanical behavior of individual elements in the model appear to reflect the different stages of brittle fracture in rocks (Bieniawski, 1967), namely; crack closure, elastic deformation, stable fracture propagation and unstable fracture propagation.

Jan 1, 1986

By John J. Sammarco

Computer-related accidents have caused injuries and fatalities in numerous applications. Normal Accident Theory (NAT) explains that these accidents are inevitable because of system complexity. Complex systems, such as computer-based systems, are highly interconnected, highly interactive, and tightly coupled. We do not have a scientific methodology to identify and quantify these complexities; specifically, NAT has not been operationalized for computer-based systems. Our research addressed this by operationalizing NAT for the system requirements of safety-related computer systems. It was theorized that there are two types of system complexity: external and internal. External complexity was characterized by three variables: system predictability, observability, and usability -the dependent variables; internal complexity was characterized by modeling system requirements with Software Cost Reduction dependency graphs, then quantifying model attributes using 15 graphtheoretical metrics the independent variables. Dependent variable data were obtained by having 32 subjects run simulations of our research test vehicle: the light control system (LCS). The LCS simulation tests used a cross-over design. Subject perceptions of these simulations were obtained by using a questionnaire. Canonical correlation analysis and structure correlations were used to test hypotheses 1 to 3 - the dependent variables predictability, observability, and usability do not correlate with the NAT complexity metrics. Five of 15 metrics proposed for NAT complexity correlated with the dependent data. These 5 metrics had structure correlations exceeding 0.25, standard errors < 0.10, and a 95% confidence interval. Therefore, the null hypotheses were rejected. A Wilcoxon signed ranks test was used to test hypotheses 4 to 6 - increasing NAT complexity increases system predictability, observability, and usability. The results showed that the dependent variables decreased as complexity increased. Therefore, null hypotheses 4 to 6 were rejected. Lastly, this work is a step forward to operationalize NAT for safety-related computer systems; however, limitations exist. Opportunities addressing these limitations and advancing NAT were identified. Lastly, the major contribution of this work is fundamental to scientific research - to gain knowledge through the discovery of relationship between the variables of interest. Specifically, NAT has been advanced by defining and quantifying complexity measures, and showing their inverse relationship to system predictability, observability, and usability.

By Robert J. Shank

This paper describes the Federal Government assistance available for northern mining development. The paper commences with a discussion of why the Federal Government should give assistance to northern mining development. It then uses a hypothetical case of a company which has a property it wants to develop to list the sectors within the . Federal Government that would have to be consulted in order to obtain federal financial assistance. The paper also outlines the type of information a company must be willing to provide the government in order to qualify for such assistance.

Jan 1, 1978

By Robert W. Bruhn

Ground movements associated with high extraction underground coal mining, such as pillar retreat and longwall, are sometimes large enough to disrupt the ground water regime as well as damage buildings and other surface structures. A U.S. Department of Energy/Bureau of Mines- sponsored subsidence study currently underway at Kitt Energy Corporation&apos;s Kitt No. 1 Mine near Philippi (Barbour County), West Virginia has provided an opportunity to monitor the ground water response above a mine panel during both developmental and pillar retreat mining. The initial findings concerning ground water effects presented in this paper indicate that total extraction mining produced significant water level declines in deep-lying strata but had little effect on water bevels at shallower depths.

Jan 1, 1985

By Propster M, Choudhry M

THIS note gives comments on the paper by Kitaev et al on p. 68 of this book and compares results with those obtained by ourselves. We wish to say that the authors are to be congratulated on their sophisticated approach to an important problem and that it complements our efforts on flow maldistribution.1-5 It is our view that Eqs. (1)-(5) on p. 69 are impressive, but unfortunately with present day computers and computational facilities, it would be quite impractical to contemplate the numerical solution of these. Eq. (8) in the authors&apos; paper, on p. 70, does provide the logical starting point for tackling flow maldistribution problems and strictly speaking this equation is more accurate than Eq. (1) in our paper in this book. We note in passing that there is direct experimental evidence to support the contention that our Eq. (1) is at least a reasonable approximation and one may question in a practical sense whether the refinement afforded by Eq. (8) in the paper by Kitaev et a/ is justified. While one must readily accept the appropriateness of Eq. (8) of Kitaev et al as a starting point, the subsequent mathematical manipulation by the authors is open to serious criticism. In order to solve this complex, non-linear equation Kitaev et al postulated irrotational flow, which afforded considerable simplification. One can argue simply on physical grounds that the assumption of irrotational flow is inappropriate, a fact which should be readily apparent on inspection of the flow fields shown in Figs. 2 and 3 of Kitaev&apos;s paper. It follows that while the starting point through the use of Eq. (8) is correct the results derived from this starting point may be suspect because of the erroneous nature of the irrotational flow assumption.

Jan 1, 1975

By B. K. Loveday

The use of large flotation machines is well established, resulting in substantial savings in both capital and operating costs. Therefore, when a new plant is designed, laboratory and pilot-plant tests should be used to simulate large flotation cells, or appropriate scale-up factors should be employed. &apos;Conference on titanium The Fifth International Conference on Titanium will be held from 10th to 14th September, 1984, in Munich, West Germany, organized by the Deutsche Gesellschaft fur Metallkunde e.V., in association with the American Society for Metals, Societe Francaise de Metallurgie, The Academie of Sciences U.S.S.R., The Japan Institute of Metals, The Metallurgical Society of A.I.M.E., and The Metals Society.

Jan 1, 1983

By O. L. Papendorf

The method presented in this paper can be used, instead of lengthy cash-flow determinations, for the calculation of present values in the face of physical growth and inflation.

Jan 1, 1981

Interest in the tantalum-niobium minerals has been greatly stimulated in Western Australia by the fact that these rare minerals occur at numerous localities in that State, and in the adjoining parts of the Northern Territory, sometimes in mineable concentrations, as at Wodgina and Greenbushes. A large proportion of the world&apos;s tantalum comes from these deposits. The late Dr. E. S. Simpson, in particular, made an extensive study of the chemistry and mineralogy of these minerals, and the following observations are based upon the examination of specimens which he and Mr. H. Bawley, Government Mineralogist of Western Australia, have submitted to me for examination from time to time. The fact that so many of the specimens have been analysed provides a unique opportunity for the interpretation of the phenomena observed in the polished sections.TANTALITE-COLUMBITE SERIESIt has long been considered, on the basis of crystallographic form, chemical analyses, and specific gravity measurements, that ferrotantalite (FeO. Taz05), manganotantalite (MnO. Taz05)&apos; ferrocolumbite (FeO. Nbz0 5), and manganocolumbite (MnO. Nbz0 5 ) form a complete isomorphous solid solution series (Simpson, 1937) and this is confirmed by study of polished sections of these minerals, Pehrman (1929) examined a series of five analysed specimens with Nbz0 5 contents as follows:-

Jan 1, 1940

By V 7. 0 / 300 dpi

WHEN the copper smelters were built, in Montana, all of the refractory products which were used in their construction were shipped in from Eastern factories. It was apparent that if a material suitable for the manufacture of these products could be found within the State, a saving of freight could be effected and a new industry built up. Prospecting for such materials was started and experiments were made with samples from numerous deposits. Considerable effort and funds were expended in an attempt to manufacture silica brick from Dillon quartz, a light colored sandstone that is found near Dillon, Mont., on the Oregon Shortline railroad. As a brick material the Dillon quartz was a failure, but it has proved very satisfactory as a silica cement. It is now being used in laying silica brick and for reverberatory furnace bottoms. A bed of quartzite that is particularly suited to the manufacture of high-grade silica brick -was finally discovered at Browns Spur, 6 miles west of Anaconda. The material from this deposit is now being used in the manufacture of the Anaconda silica brick, which have gained a wide reputation for heat-resisting and lasting qualities. The analysis of all average sample of this quartz is: SiO2,, 96.7; Fe203, 0.3; Al203, 2.5; CaO, 0.3 per cent. The very low percentage of fluxing ingredients makes this a most refractory material. All of the Anaconda silica brick are hand molded. Various types of brick machines have been tried, but the hand-mold process proved the best suited to the manufacture of silica brick from this material. The silica is first put through a jaw crusher and is then clumped into wet pans, where 4 per cent. of lime paste is added, to produce a bond. Without the lime the. material would not be plastic enough to mold. After a few minutes&apos; grinding in the wet pans the material is conveyed to the molder, who forces it into the molds by hand. The brick are then dumped on pallets and placed in the drier, where they are left until dry enough to be set in the kilns. Some of the brick are re-pressed before being dried. They are burned about five days, in round down-draft kilns. It is not necessary to have as much heat in the kilns as the brick will be subjected

Jan 9, 1913

By N. A. Smith, R. J. Fowell, J. L. Hislam

Abstract: Data are presented from two sites in southeast England, where problems were encountered in tunnelling through ground containing flint. In response to the difficulties, substantial laboratory testing programmes were initiated to determine the strength of the flints.It is shown that the strength varies very considerably, even within a single flint particle and that the practice of estimating unconfined compressive strength by a single multiplier applied to the point load strength index (Is(50)) may give misleading results. The preparation of UCS specimens for testing was found to be very difficult and it is recommended that tunnel machine capacity is assessed relative to Is(50). Résumé: Des données sont presentées sur deux sites dans le sud-ouest de l’Angleterre,où le perçage d’un tunnel dans un sol contenant du silex a posé des problémes. En consequences de ces difficultés, des programmes substatiels de recherché en laboratoire ont été initiés afin de déterminer la resistance des silex. Il est demontré que la resistance varie considérablement, même au sein d’une particule de silex, et que la pratique de estimation de la résistance en compression non confinée, (UCS) par le biais d’un simple coefficient appliqué au ‘point load strength index (Is50)’ pourrait donner des resultants trompeurs. La préparation de specimens UCS destinés aux tests s’est avérée trés difficile et il est recommandé que la capacité de la machine de perçage de tunnels soit calculée relativement au Is50. Zusammenfassung: Daten von zwei Standorten in Südosten von England, wo Probleme beim Tunnelbau durch feuersteinhaltigen Grund antraffen, sind angegeben. Wegen diesen Schwierigkeiten wurden Laboratoriumsforschungsprogramme eingeleitet, um die Festigkeit von Feuersteinen zu bestimmen. Es wurde gefunden, dass die Festigkeit sehr unterschiedlich war, selbst bei einzelnen Feuersteinstücken, und dass die Praxis, die unbegrenzte Kompressionsfestigkeit (uKf) auf Grund eines einzigen Multiplikationsfaktors vom Punktladefestigkeitsindex (Is50) abzuschätzen, zu irreführenden Resultaten führt. Die Vorbereitung der uKf Prüfstücke war sehr schwierig und es wird vorgeschlagen, dass die Kapazität der Tunnelbaumaschine in Abhang der Is50 bestimmt wird.

Jan 1, 2003

By Ailton Lopes de Oliveira

A Usiminas, como empresa de ponta na produção de aços planos, visando manter e ampliar a sua liderança na produção e comercialização destes produtos, investiu uma elevada soma na modernização de sua linha de produção. Em 2012 foi instalado na Usina de Cubatão, o moderno Laminador de Tiras a Quente e, em agosto de 2013, foi dada a partida operacional da nova linha de Decapagem 03. O objetivo da nova Decapagem 03 é agregar valor em seu portfólio de produtos, complementando assim a nova linha de produtos ofertados com novas dimensões e qualidades. A nova mistura de produtos laminados a quente atende maiores faixas de espessura e largura, além de oferecer tipos de aço não produzidos anteriormente. Este trabalho visa mostrar as principais etapas deste projeto, os benefícios e os resultados preliminares alcançados com a instalação da nova linha de produção. A Decapagem 03, por seu elevado nível tecnológico, é considerada "estado da arte em produção de bobinas decapadas", garantindo assim a obtenção de produtos de grande valor para os clientes, atendendo aos mais rigorosos padrões de qualidade.

Jul 30, 2018