Search Documents

Council for 2005/2006 President W.H. van Niekerk President-elect R.P.H. Willis Vice-presidents Senior R.G.B. Pickering Junior A.M. Garbers-Craig Immediate Past-president F.M.G. Egerton Honorary Treasurer J.A. Cruise

Jan 1, 2006

By Gray Mullins

The construction of drilled shafts as well as other cast in place foundation alternatives relies heavily on good practices from the contractor, engineer, and inspector in order to produce a quality foundation element. As many of the installation methods involve blind concreting processes, it is difficult to be certain of an intact concrete mass of the intended dimensions. A new integrity test has been developed that provides additional insight into the integrity of drilled shaft concrete. By measuring the temperature throughout the shaft via standard access tubes, the measured temperature profile can be compared to the normal signature associated with a shaft of the specified size. This article provides an overview of the new method development, test procedure, analysis, and results.

Jan 1, 2010

By H. Saroglou

The anisotropic behaviour of Athens Schist has been brought out through the testing of specimens with varying orientation of schistosity with respect to the major principal stress under uniaxial, triaxial and dynamic conditions. A large number of results from tests on intact rock specimens of the Athens Schist were statistically analysed and evaluated.

Jan 1, 2004

By C. J. Cutler

Metallurgical accounting for toll treatment smelters pose a number of challenges. Multiple feed stockpiles have to be accounted for as part of the monthly recovery estimation. Moreover, multiple metallurgical intermediates make up part of the in-process inventory, which also influence the monthly recovery calculation. Errors propagate from the measurements of volumes, assays, moisture fractions and bulk densities in the various material types through multiple steps up to the point where the final recovery is calculated. These errors contribute non-linearly to the variance in the final recovery estimate. This paper develops the mathematical formulation for variance propagation in toll smelting operations, including the effect of in-process inventory, assuming measurement biases have been eliminated beforehand. Operational data from a Southern African copper smelter is used for a case study. The method of propagation of variance showed that uncertainties in stockpile assays were the main contributors to variance in the recovery estimate. Variance in the volume and bulk density uncertainties contributed a secondary, yet significant, proportion to the overall recovery variance. It was determined, for the given case study, that the recovery variance depended on the calculation method used and that variance propagation via the two-product formula was smaller than recovery variances calculated via the standard recovery formula. However, the probability that the two product formula will give inaccurate (versus imprecise) results is significantly more due to the practical difficulty of equiprobable sampling of tailings streams from smelter plants (which includes materials such as slags and flue dust). Recommendations are made on how to achieve a reduction in overall uncertainty for toll treatment smelters. Keywords: metallurgical accounting, copper smelters, pyrometallurgy, variance propagation, errors, precision, sampling

Jan 1, 2006

By S. V. Rungan

Since 1994, South Africa has been the subject of international attention, especially in regard to its transformation initiatives, which aim to redress the post-apartheid imbalances. Mining, as a major employer and one of the major industries in South Africa, has been the focus of the government?s Black Economic Empowerment initiative with the introduction of the Minerals and Petroleum Resources Development Act and the Broad?Based Socio?Economic Empowerment Charter for the South African Mining Industry. The historical background to South Africa?s transformation and the role of the mining industry are pivotal to an appreciation of certain aspects of the Minerals and Petroleum Resources Development Act and the Broad?Based Socio?Economic Empowerment Charter for the South African Mining Industry. The issues around Black Economic Empowerment and the enabling of a smooth transition to the South African mining industry of the future are explored in this paper.

Jan 1, 2005

By S. Rajendran

The area of the Exclusive Economic Zone (EEZ) of India is about 2.014 million km2 and the resource evaluation of placer deposits is one of the objectives of Government of India. Placers are detrital metallic minerals found on beaches and in the near shore areas. Quantitatively more important are placer deposits of light heavy minerals such as zircon, ilmenite and rutile. Rivers and other drainage channels are the main carriers of the placers which contain heavy minerals like magnetite, ilmenite, garnet, zircon, monazite, rutile etc. The present beach as well as part of the shelf was land during Pleistocene as a result of the world wide lowering of the sea levels. The coast line shifted a number of times. Hence, the heavy mineral placers on the beaches are expected to extend to offshore areas chiefly with Pleistocene lowered sea level strands. India has extensive deposits of heavy mineral placers along the beaches. Placer deposits of heavy minerals occur in discontinuous patches on the beaches along many parts of the east and west coasts. Along the central west coast of India (12??N - 19? N lat.) the placer containing 14 - 17% ilmenite form an estimated reserve of 4 million tons. On the Ratnagiri coast of Maharashtra, the proportion of heavy mineral varies between 54 and 70% in the bulk samples, consisting mainly of 14 - 39% magnetite and 16 - 30% ilmenite. The National Institute of Oceanography (NIO) surveys show that the sediments off the central west coast consist largely of silty sand, sand silt and clay. The core samples show that a reddish brown clay overlay olive gray clay which in turn overlay heavy mineral rich sands. The heavy mineral concentration ranges upto 90% and has mainly ilmenite and magnetite with minor quantities of apatite, rutile, zircon, kyanite etc. Siddiquie et al. reported 42 - 75% TiO2 in the ilmenite.

Jan 1, 1998

The results of a series of physical model studies of the stability of jointed rock slopes carried out some years ago are described. These models were tested under centrifugal loading. Four ?geological? structures were tested; all had the same joint orientations and strengths, but the relative spacing of the joints was different. The results showed that the mechanisms of failure of the slopes varied for the different models, and the gravitational loads at which failure developed also varied. The following conclusions are drawn from the results of the physical model tests: ?the mechanism of slope failure is by progressive deformations throughout the slope ?the ratio of the spacings between the different sets of discontinuities exerts considerable influence on the slope failure ?in the models tested, the intact material strength had no noticeable influence on the stability of the jointed rock slopes(note that for hard rock, similitude conditions indicate a prototype slope height of 300 to 400 m, and therefore intact rock failure might not be expected under simple gravity conditions, i.e. no tectonic stresses) ?rock slope failures are three-dimensional and in general are not amenable to two-dimensional simplification ?knowledge of the orientations of discontinuities in the slopes does not allow prediction of a unique failure surface, nor of a volume of failure. The volume of failure is determined to a large extent by the plan configuration of the slope.

Jan 1, 2006

By L. C. Stilwell

Input-output analysis is a major branch of quantitative economics, and is used to analyse the flow of goods and services between production sectors in a national economy. Its purpose is to determine the relative value-adding capacity of each sector. The model has also, in recent years, found increasing use in assessing the environmental and ecological impact of development projects. It has, however, never been applied to individual production facilities, such as large mines, which themselves have complex economic structures, through which there is a flow of goods and services. Conventional cost and accounting systems, as used on mines, treat production sectors as separate cost centres, and do not determine the inter-relationships between them. This can lead to incorrect conclusions on the relative value of sectors and their impact on the total economic performance of the facility. This paper explains the basic principles of input-output analysis, and presents an example of its application to a simplistic model of a mine, which is used in the absence of any real data. The paper concludes that, by forcing definition of the value adding function of each sector, input output analysis will facilitate control of inputs, or costs. This will result in optimal application of resources and exploitation of ore reserves. The authors realise the model needs to be tested on an operating mine, and hope this paper will result in an opportunity to do so. The authors wish to thank the anonymous referees for their valuable comments.

Jan 1, 2000

By Jack Curran

KANSAS CITY, MO - Performing one of the most impressive urban building-implosion projects in recent memory, Tulsa, Oklahoma-based Dykon Explosive Demolition Corp. and Omaha, Nebraska-based Anderson Excavating recently felled the landmark Columbia Bank Building in downtown Kansas City, Missouri, USA. Although every structural blasting project presents special challenges, this undertaking was most notable for its unusually unique structural design, tight clearances, and high risk to adjacent structures.

Jan 1, 2003

By Y. Wang, E. Forssberg, A. Johansson, B. Chan

A super-conducting high gradient magnetic separator with matrix vibration in dry separation mode is a powder purification device, which has been used to remove weakly magnetic impure particles from fine calcite powders below 53 µm in this study. A fundamental question concerned is the evolution of the matrix clogging under gas-solids loads. This paper presents the improvement of the separation selectivity using a method of mechanically based vibration on the matrix in the separator. The functions of the matrix vibration are discussed. The results indicated that the mechanically based vibration on the matrix within a high intensity magnetic field while a feed was introduced in an air stream, was found to be effective for the dry purification of fine powder materials.

Jan 1, 2001

By James Pile

Long, high capacity, highly tensioned, cable bolts (strand bolts), stiff enough to be installed with resin like a solid bolt, yet flexible enough to be used in any lengths, have been widely used in Australian coal mines since the early 1990?s. A brief history and update on recent developments of this technology is provided. The first major US trial of this Australian technology, has recently taken place at BHP Billiton?s San Juan longwall coal mine in New Mexico. Thirty-five foot long, high capacity, highly tensioned, post-grouted cable bolts are being used to provide active secondary support of intersections in areas where operator safety and life of mine considerations are paramount, and standing support cannot be installed for reasons of equipment access. The cable bolts are resin anchored into overlying sandstone channels, tensioned, and post-grouted. The installation procedure and support results for these highly tensioned cable bolts are given.

Jan 1, 2007

By G. Laing

On scheduled commissioning and effective operation of a solvent extraction circuit relies on getting the design of both the core contact equipment and the peripheral plant right. Experience has shown that poor performance of new plants is frequently a result of ?utility? systems that do not match the requirements of the circuit, rather than the mass transfer equipment itself. Both the operator/owner and designer need to understand the ?complete requirements? for the circuit to get the balance of the design right. This paper reviews generic issues, frequently overlooked or altered during cost-cutting exercises, which have a significant impact on plant performance.

Jan 1, 2002

By Todd Wanless

This paper addresses the challenges experienced by the designer and three government agencies during implementation of major improvements for the Turkey Creek Tunnel in Kansas City, Kansas. The tunnel serves as a vital stormwater conveyance system for upstream flood control. Major structural deficiencies were identified within the tunnel including complete loss of sidewall and invert. Without immediate attention, complete loss of the tunnel arch could lead to blockage and extensive remedial repairs under difficult conditions. Considering that tunnel flows must be maintained during construction, a phased design and construction process has been implemented to expedite stabilization of the erosion cavities followed by tunnel liner repairs.

Jan 1, 2008

By H. I. Kim

The leaching of a complex matte in chlorine and chloride media was studied. The matte was prepared from manganese nodules by the reduction smelting-sulfidation route. From XRD analysis, the major phases of the matte were identified as CuFeS2, CuS2, (FeNi)9S8, (FeNi)S2, Ni9S8, Ni3S2, (CoFeNi)9S8 and Co metal. Investigated were the chlorine, hydrochloric acid, hydrochloric acid-oxygen, ferric chloride, ferric chloride-oxygen, cupric chloride and cupric chloride-oxygen systems. The results are discussed in terms of reagent concentration, retention time, leach temperature and gas sparging rate. The chlorination process resulted >99% metal extraction efficiency within a short retention time and at atmospheric temperature. However, there were no preferential extractions of Cu, Ni and Co with respect to Fe. The cupric chloride-oxygen system produced leach liquors with the lowest Fe content and with a high base-metal extraction. Sulfide sulfur was converted to mixtures of elemental sulfur and sulfate in all the studied systems.

Jan 1, 2009

By J. S. Ll. Leach, M. B. Bever

THE system copper-nickel exhibits complete solid and liquid miscibility1 The thermodynamic properties of such a system would not be expected to deviate greatly from ideality. Although the evidence is conflicting, anomalies in the composition dependence of various physical properties of solid copper-nickel alloys suggest that mixing may not be ideal.' From measurements of the Hall coefficient it has been concluded that clustering occurs in these alloys. ' Considerations involving the phase diagram of the ternary system copper-nickel-chromium have led Mei-jering3 to predict a positive heat of formation for solid copper-nickel alloys. An electrochemical investigation of the activity of nickel in copper-nickel alloys showed unexpectedly large positive deviations from ideality.4 wagner5 has proposed that if the entropy can be considered ideal, these measurements would yield the following equation for the heat of mixing at 700°C H" = 3380 x,vl (l-xVi) cal per g atom [I1 The heat of formation at 722°C of solid copper-nickel alloys of the equiatomic composition has been measured in a reaction calorimeter as 540 cal per g atom. This note reports calorimetric measurements of the heat effects on dissolution of some copper-nickel ndon: in tin. These measurements were preliminary to a larger investigation, which was later discontinued. From them the heats of formation of the alloys can be calculated, if certain assumptions are

Jan 1, 1960

Due to the reduction in frictional resistance, the characteristics of joint infill have a major role to play on rock mass instability. This paper elucidates the laboratory behaviour of graphite infilled joints based on a large-scale shear apparatus under constant normal stiffness (CNS). Discontinuities in a graphite mine have been simulated using high strength gypsum plaster, with the joints infilled with compressed graphite layers. The Fourier series was employed to characterize the joint surface, and the method of using the Fourier coefficients for the prediction of dilation and normal stress with displacement is explained. Die Charateristik von Verbindungsfüllungen hat einen wichtigen Einfluss auf Felsmassenstabilität aufgrund der Verringerung des Reibwiderstandes. Diese Veröffentlichung untersucht das Verhalten von Graphit gefüllten Verbindungen im Labormaßstab mit einer Methode die auf einem gross-umfang Apparateprinzip unter konstanter Normal-Steifheit beruht. Unregelmässigkeiten in einer Graphit Mine wurden mit Gypsum Gips von hoher Festigkeit simuliert, die Verbindungen wurden mit kompressierten Graphitschichten gefüllt. Fourier Reihen wurden angewandt um die Verbindungs Fläche zu Characterisieren. Die Methode die verwendet wurde um die Ausdehnung und Normalkraft mit der Verschiebung mit Hilfe von Fourierkoeffizienten zu bestimmen wird beschrieben. Due à diminution des résistances par frottements, les caractéristiques des joints de remplissage joue un rôle majeur sur les instabilités de la roche. Cet article étudie le comportement en laboratoire des joints de remplissage en graphite à partir d’un dispositif de friction à grande échelle sous rigidité normale constante. Les discontinuités dans une mine de graphite ont été simulées grâce à un plâtre à haute teneur en gypse, dont les joints ont été remplis de couches de graphite compressées. La caractérisation de la surface des joints a été réalisée avec les séries de Fourier. La méthode utilisant le coefficient de Fourrier pour la prédiction de la dilatation et de la compression en fonction du déplacement est également expliquée.

Jan 1, 2003

By D. Komljenovic

This paper presents the use of queuing theory in truck fleet sizing in open pit mining operations. In the first part, a methodology is developed by which an optimal ratio between the size of shovels and trucks may be determined. The second part gives the fundamentals of the queuing theory and its application in analyzing shovel and trucks. The stochastic character of involved times (loading, truck cycle, etc.) is taken into consideration. Using the above theory, the optimal truck fleet size in actual conditions may be estimated. Minimal operating cost of the working system (shovels-trucks) represents the basic requirement of the analyzed process. The methodology was validated on Caterpillar front-shovel ? truck combinations.

Sep 1, 2004

By George A. Lawrence, J. C. McHardy

"Field operating experience with an improved flotation mechanism for handling various flotation applications is covered in this paper. Some aspects of designing flotation machines are also presented. Operating data from extensive testing of commercial size equipment under actual plant operating conditions in the following applications is detailed:1. Copper Flotation2. Fine Coal Flotation3. Base Metal Sulfide FlotationDesign features, design improvements, modifications tested, and overall performance data are reviewed. Some mecl1anical performance data as well as metallurgical performance results are presented. Some comparisons with conventional flotation equipment are reported in this paper.Flotation sizing theories are reviewed and an actual equipment selection ex2.mple is presented. Scale-up criteria used for developing large cells are briefly covered.The paper concludes with a brief review of anticipated future flotation equipment design needs. IntroductionThe mining/milling industry is faced with increasing pressure to cut costs while maintaining product quality and indeed, in some instances, expanding production. For copper, nickel, iron, molybdenum, lead and zinc sulphides, coal, phosphate and some other minerals;, flotation remains the primary method of concentration and recovery of the valuable mineral away from the gangue. Cost reduction in flotation can be broadly focused on two areas:1. Flotation Chemicals2. Flotation Equipment"

Jan 1, 1985

By R. Grimard, M. Gamache, L. -P. Bigras, P. Cohen

This paper describes a real-time fleet management system for an undergroun mine. Dispatching, routing and scheduling are handled simultaneously, taking into account the mine status, operational constraints and vehicle location information. Each assignment decision takes into account the traffic on the road segments of the mine network, whether road segments are bi-directional or uni-directional, and ensures that each LHD (load-haul-dump) vehicle arrives at loading and dumping points with the correct orientation. Such a system can be used either as a simulation tool for strategic planning or as a real-time managing and optimizing system for operations. In the simulation mode, the system can accurately estimate the impact on productivity of decisions such as the development of waiting areas (bays, sidings), or the addition (elimination) of vehicles to the fleet in operation. When used for real-time dispatching, routing and scheduling of vehicles, the system can optimize production with respect to various assignment criteria such as cycle-time minimization or deviation from a target production plan.

Jan 1, 2004

By R J. Johnson

The development of "SANFO" has provided the Mining Industry with a LOW COST HIGH GAS VOLUME, VARIABLE DENSITY, Blasting Agent which can be blended "On Site" in a simple Agitator mixing and charging system by mine site employees.

Jan 1, 1996