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By C. Musingwini

The South African mining industry continues to be a major source of employment at a time when at least 25 per cent of the working age population is unemployed. At the same time the industry faces a skills shortage in many of the disciplines necessary for its future health. The University of the Witwatersrand, University of Pretoria, University of Johannesburg, and University of South Africa have historically produced mining graduates for the South African mining industry with any shortfall being met by the recruitment of overseas graduates. More recently, the global shortage of engineers and other mining industry professionals has seen a reversal of this trend and a very significant emigration of well-educated and highly skilled personnel. The traditional career path for mining graduates is in production and mine management. However, there is the parallel (and possibly more pressing) need for specialized skills in such fields as ventilation, rock engineering, mine planning, mineral resource evaluation, and mineral asset valuation. Chronic shortages in these essential areas continue to hamper the development of the industry and may well frustrate its ambitions to be safe, healthy, and profitable into the future. The permeability of skills across sectorial boundaries within the mining industry requires that skills shortages in the platinum sector are not looked at in isolation, but within the context of the entire industry. This paper reviews the efforts being made by the universities, at both undergraduate and postgraduate levels, to meet the needs of the South African mining industry in terms of the required numbers and the range of specialized skills.

Jan 1, 2013

By J. du Plooy

Mintek has implemented a training scheme that provides students with the experiential training requirement for the National Diplomas in Chemical Engineering and Extraction Metallurgy. This note describes the main features of the scheme and the course content, and our view of future developments in this area.

Jan 1, 1998

By Alexander B. Reeb, Richard J. Varuso, George M. Filz, Jehu B. Johnson

"T-walls, which are concrete floodwalls in an inverted “T” shape, are an integral component of the Greater New Orleans Hurricane and Storm Damage Risk Reduction System (HSDRRS). In order to resist large lateral flood loads, T-walls are typically supported on long batter piles that extend through the weak and compressible clays and peats commonly encountered in southern Louisiana. Since the piles are battered, settlement of the compressible foundation soils can result in loads acting normal to the piles and induce pile bending moments. Therefore, the design of pile-supported T-walls is a complex soil-structure interaction problem that requires detailed and careful numerical analysis to accurately estimate the stresses and bending moments in the piles. For this paper, numerical analyses were performed for three cross sections that each included a two-pile T wall system that was installed within a 15-ft tall new levee embankment. The cross sections were identical except that the elevation of the T-wall base was varied. This paper discusses the analyses, and it compares the influence of settlements and flood loading on the pile stresses and bending moments. In addition, this paper includes general recommendations for the analysis and design of pile-supported T-walls in practice.INTRODUCTION AND BACKGROUNDThe recently completed Greater New Orleans Hurricane and Storm Damage Risk Reduction System (HSDRRS) includes 350 miles of levees and floodwalls and is designed to defend against a 100-year storm surge event. The floodwalls predominantly consist of I-walls and T-walls. I-walls are comprised of a sheet pile wall curtain capped with a monolithic concrete wall above grade. T-walls are similar to I-walls, but they include a wide concrete base at grade, which forms an inverted “T” shape, and they are generally supported by long batter piles that provide additional lateral and rotational stability for resisting flood loads.During Hurricane Katrina, several I-walls failed, resulting in large breaches and devastating flooding (Duncan et al. 2008, IPET 2009). T-walls on the other hand performed quite well, including T-walls that were overtopped and eroded on the protected side, yet still did not collapse. As part of the HSDRSS, more conservative designs and height restrictions were required for I-walls (USACE 2011), and a number of I-wall sections were replaced with T-walls. However, the design of pile-supported T-walls is complex and requires careful consideration of both flood loading and settlements."

Jan 1, 2017

By G. Richards Gwinn

The mineral graphite, a form of carbon, has been known for hundreds of years, and, was first used commercially as a coloring agent. Its true identity, however, was not recognized until the end of the eighteenth century, and its commercial development did not become extensive until near the close of the ninteenth century.

Jan 1, 1943

Henry Walker Eltin (HWE) are the mining contractors for Gloucester Coal at Stratford mine, which is in an environmentally sensitive area in the Avon Valley, NSW, Australia. Normal blasting at Stratford is done in a “stand up” or “box cut” mode to suit the truck and shovel operations. Recently an opportunity of doing a throw blast became available when part of a ramp had to be blasted to accommodate changes to the pit design while not damaging the remainder of the ramp. The objective was to maximise throw into the void in order to minimise excavation costs by reducing the amount of overburden to be moved by the excavation fleet. It was necessary that the best result be achieved while staying within the vibration and airblast limits at a neighbouring property and nearby township. Both objectives were achieved through the application of Orica’s knowledge of blast design, modelling and i-konTM electronic detonators.

Jan 1, 2003

By H. P. Jacobi

"The last 25 years have seen tremendous economic pressure placed upon the base metal processor. Industry has responded with technological innovations that have contributed to significant reductions in capital and operating costs. Major changes in processing machinery and philosophy are highlighted for the main unit operations of a base metal mill. Changes in our attitudes on what is environmentally acceptable are also discussed.INTRODUCTIONNewton's law of motion paraphrased states that nothing will change unless there is a pressure to do so.Aase metal processing as a primary commodity related industry has been under severe economic pressure over the last 25 years. This has been brought on by over capacity from new operations in the L.D.C. 's, through material substitution in a host of traditional base metal applications and generally reduced world-wide economic activity. In addition to shrinking markets our collective environmental consciousness has raised effluent standards and workplace hygiene and the employee's as well as government's economic expectations of how much ought to be derived from ''nature's riches''.Industry has responded with technological changes which, it was hoped, would counteract the cost squeeze in which it found itself.I would like to briefly enumerate the major changes, as I see them, that have taken place in the main unit operations that form the normal processing chain for base metals.While the following paper will mention several brands of products, I would like to emphasize that these are the ones that I am most familiar with and is not to say that they are the only manufacturers which have contributed to changes. In fact it ls fair to say that all makers of mining and processing equipment have made improvements to their products, to a greater or lesser degree; they have had to, to still he in business in 1986."

Jan 1, 1987

By Y. C. Han

The advances in seismic design considering soil-structure interaction or soil-pile-structure interaction are described using a substructure approach. The nonlinearity of soil is considered approximately using a boundary zone model with non-reflective interface, and computer programs are available for practical applications. The validation of model is confirmed with dynamic tests on piles in the field, and the results for a single pile are used to compare with the predictions in this study. The liquefaction for sand soil layer can be accounted for, and a case of liquefaction is discussed. Two practical examples are examined, a vacuum tower structure supported on foundation of steel pile group and a table top structure supported on foundation of concrete pile group. To illustrate the effects of soil-pile-structure interaction on the seismic response of vacuum structure, different base conditions are considered, rigid base, i.e. no deformation of the foundation; linear soil-pile system; and nonlinear soil-pile system. The method introduced can be applied to the design of tall buildings, bridges, industrial structures and offshore platforms with soil-pile-structure interaction under seismic or dynamic loads.

Jan 1, 2010

Column flotation has been successfully implemented on a production scale in the Athabasca oil sands. In this application, bitumen is recovered and mineral matter is simultaneously rejected from a middling stream originating from a primary separation vessel. Exploiting the natural hydrophobicity of bitumen, the middlings streams have traditionally been processed utilizing conventional, mechanical flotation cells. Although these cells offer adequate bitumen recovery and mineral rejection rates, operating costs are high due to the required maintenance of the wetted mechanical components. In comparison, column flotation provides superior metallurgical performance while offering a lower maintenance demand. Both metallurgical and mechanical characteristics of column flotation are discussed to demonstrate the benefits of this technology for the recovery of bitumen from oil sands.

Jan 1, 2012

By R. M. Lamya

The kinetics of copper cementation during atmosphere leaching of a Ni-Cu matte in CuSO4-H2SO4 solution was studied as a function of initial copper ion concentration, initial acid concentration, temperature, stirring rate, particle size distribution and pulp density. It was found that all these process variables influenced the rate of cementation. A two-stage rate of reaction was observed inmost of the experiments, with the rate of cementation in the initial stage being slower than that of the subsequent second stage. The increased rate of cementation in the second stage was attributed to the enhancing effect of the surface deposit. The cementation process was found to take place by two different rate-controlling mechanisms. At a temperature range of 50?70°C, an activation energy of 74.6 kJ/mol was obtained, indicating a surface reaction controlled process. At higher temperatures (70?80°C) a lower value of activation energy was observed (18.2 kJ/mol), indicative of a process controlled by diffusion through surface layers. The structural characteristics of the cemented deposit could not be determined in the investigated system where the deposit was mixed with the leach solid residue.

Jan 1, 2005

By F. T. Cawood

The new South African Mineral Policy has major implications on the way mineral rent will be collected and shared between the stakeholders in future. Although the policy does not supply details on how this will be done, drastic departures from practices under the previous dispensation require a new approach. For example, there introduction of the ?right to mine? principle implies that the repealed lease consideration concept will be expanded to all minerals. The new policy also makes provision for predetermined standard terms and conditions for all prospecting and mining permissions. It also states that, regardless of whether the mineral rights are state or privately-owned, all prospecting fees and mineral royalties will be determined by state officials after consultation with the registered holder of the mineral rights. This paper proposes a standard mineral royalty formula that complies with the principles mentioned in the White Paper and has been shown to be internationally competitive.

Jan 1, 2001

By Derek J. Cyr

Climate has an immense impact on the properties of Athabasca oil sands and the ease or difficulty with which it is excavated and extracted. During the winter months, exposed oil sands surfaces freeze. When hydraulic and electric shovels used in the various operations in the Fort McMurray area excavate the benches, large frozen lumps are created. These lumps are either destined for a lump dump where increased costs are incurred due to rehandle, or they are sent to the primary crushers where they can cause significant downtimes by jamming the crusher. The crusher down time can sometimes be in the order of hours of lost production. Studies on data from two consecutive winters at Syncrude Canada?s North Mine show a high correlation between climate and the generation of frozen oil sands lumps. Temperature, ground cover, traffic, bench exposure time, oil sands grade and moisture content all contribute to this problem. A 1D frost penetration model was used to predict the depth of frost expected in oil sands and the corresponding likelihood of frozen oil sands lumps. To combat the challenge of frozen lump generation, a number of proactive and reactive measures can be taken: artificial snow, shallow ponds, scheduling, blasting or ripping.

May 1, 2004

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 H. Jehn

Like some other Pt-group metals palladium shows a low but considerable solid solubility of oxygen, which was found already from oxidation studies. The oxygen solid solubility of palladium in equilibrium with gaseous oxygen has been investigated at 900 - 1300 °C in oxygen (665 mbar) and air by gassing and analyzing polycrystalline samples. The 0-concentrations range from 40 to 90 ppm and decrease with rising temperature. The isobaric solubility can be represented by the least-squares fit log c0 = 0.5 log p02- 0.32 + 920/T (c0 in wt. ppm, p02 in mbar, T in K). The thermodynamic data of the exothermic solution reaction are calculated to ?H°= -17.6 kJ?mol-1 and ?S° -76.5 J?mol ? K-1. The behaviour of palladium in an oxygen atmosphere is characterized by the simultaneous reactions of the solution of oxygen in the metal and the formation and evaporation of volatile oxides besides the pure metal evaporation.

Jan 1, 1984

By James A. Bachmann, Christopher J. Gray

On December 26, 1994, at 1:00 am, Santa Fe Pacific Gold's Twin Creeks Mine experienced a major highwall failure involving over 2.5 million tons. The resulting effects of this slide were thousands of ounces of gold that were now deferred and an unstable wall above which made mining the slough material unsafe.

Jan 1, 1996

By J. H. Schulman, M. H. Buckenham

R. W. Christy (Manager of Sales, Sanitary Engineering Equipment, Link-Belt Co.) and C.D. Rubert (Barrett, Haentjens & Co.) — Messrs. King and Schepman have presented an excellent paper which outlines the general practice in the design of thickener mechanisms. Lifting devices, controls, special applications and underflow pumping arrangements have been reviewed in detail. Pumping arrangements were illustrated which eliminate the need for an expensive tunnel beneath the thickener floor. Most of those illustrated have the common feature of a relatively long underflow suction line extending from the hopper floor to the pump located on the bridge at the periphery of the tank. The authors limit these arrangements to comparatively dilute or thin slurrys. It is implied that dense and coarse concentrates, which are difficult to pump, cannot be handled unless a tunnel is constructed. Fig. 1 shows an underflow pump arrangement which negates the need for a tunnel but which permits the operator to convey a heavy dense slurry. The pump is mounted directly on the fixed hoist platform and the impeller is located at the base of the steel center column. Priming water is not needed. The column

Jan 1, 1963

By Arturo Ressi di Cervia

Construction of the drilled shafts for the Brightman Street Bridge Replacement Project were not only challenging due to working over the water but were also challenged by changed soil conditions, concurrent work being performed by an adjacent contractor on the same project, environmental restrictions and severe winter conditions. A total of 36 x 8 feet diameter drilled shafts with 7.5 feet rock sockets were installed for the East and West bascule piers. This project also included Osterberg Cell load testing on two production drilled shafts at each the East and West bascule piers. The results from the load test program were used to fine tune the design of the drilled shaft rock sockets. From a constructability standpoint the reverse circulation drilling method with a pile top drill rig proved to be an excellent choice for drilling the overburden and rock sockets of the large diameter deep drilled shafts.

Jan 1, 2003

By S. Dixon

The Peñasquito deposit in Mexico is one of the largest grassroots precious metal discoveries developed in recent years. Goldcorp Inc. acquired the gold-silver-lead-zinc property with the acquisition of Glamis in 2006. The Peñasquito property is located in the northeast corner of Zacatecas state, Mexico. The elevation of the property averages 1,900 m (6,200 ft) above sea level. It is situated in a wide east-west valley. Minera Peñasquito, S.A. de C.V., wholly owned subsidiary of Goldcorp Inc. has operated twin SABC-flotation lines since June 2010. Each line is capable of processing 50,000 tonne per day using a SABC grinding circuit followed by flotation to produce lead and zinc concentrates. The addition of a Polysius Polycom HPGR 2417 with dual 3,000 kW drives to reduce the crushed pebbles produced by the SAG mills was planned to increase production to 65,000 tonne per day per line. The production has been limited to 100,000 tpd due to operating issues in the grinding circuit. The operating issue has been the amount of pebbles generated by the SAG mills is significantly less than originally planned. This paper describes the planned installation of a crushed augmented feed to maximize utilization of the HPGR capacity. This coupled with full utilization of the SAG and Ball Mill available energies there is the potential to achieve a 50% total capacity increase from the grinding circuit.

Jan 1, 2012

By António A. Henriques, António Gomes Correia, Ana Teixeira

"Abstract Pile foundations are often used for important structures, and thus, reliability evaluation is an important aspect of the design. Reliability methods have become increasingly important as decision support tools in different areas. The main benefit of reliability analysis is that it provides quantitative information about the parameters (uncertainties) that most significantly influence the behaviour under study. In particular, the design of pile foundations still involves many limitations and uncertainties, particularly when there is not enough investment in soil characterisation and/or pile load tests. In addition to the uncertainties associated with soil characterisation, physical, statistical, spatial and human uncertainties exist. In this subject, the primary purpose of this paper is to demonstrate the application of reliability methods to geotechnical pile design (axial load). It also presents a simple and practical approach to performing it using Monte Carlo Simulations, intending to provide knowledge for code harmonisation and encouraging the development of such methodologies in geotechnical practice. Sensitivity analyses are shown to understand the influence of each uncertainty type coming from different sources. An application example indicates, corroborating other studies, that the model error is the most influent uncertainty. As such, when using the different models (SPT-, CPT- and PMT-based) for bearing capacity, the results emphasise the need for a well-defined and wellcharacterised resistance model, also these results allow the engineer to understand how important the load tests can be to achieve reliable results and economic designs.1 IntroductionUnlike the approach to reliability evaluation used in structural engineering, the traditional procedure used in geotechnical designs addresses uncertainties through high global or partial safety factors (SF), mostly based on past experience. However, this approach to addressing uncertainties does not provide a rational basis for understanding their influence on design.Furthermore, the new regulation codes and social concerns, such as the sustainability or the economy, are imposing geotechnical engineers to increase their ability to deal with uncertainty in a direct and more rational way. Designs should be economic, sustainable and reliable at the same time. Concerning the reliability part of design, different approaches can be done, but the most important thing to keep in mind is the simplicity and efficiency of the tools and applied methods."

Jan 1, 2014

By A. Griffiths, G. Vickell

"INTRODUCTIONA successful cyanide destruction process has to ensure environmental compliance at reasonable cost. That this is possible with hydrogen peroxide is shown by the fact that over twenty gold mines either already use H2O2 or intend to start using it within the next few months. About half of these mines are in Canada.This growth is remarkable, considering that the first treatment plant to use H2O2 for detoxifying cyanide was commissioned less than five years ago at Ok Tedi, in Papua New Guinea.Hydrogen peroxide is being applied to a wide range of situations, including:Treatment of CIP pulps; examples: Ok Tedi, PNG; Hope Brook, Nfld.Treatment of barren bleeds and filtrates; examples: Nickel Plate, B.C.; Puffy Lake, Man.Treatment of tailings pond discharge; examples: Detour Lake, Ont., Page Williams, Ont.Treatment of excess heap leach solution; examples: Hope Brook, Nfld; Gordex, NS.Treatment of barren heaps after heap leaching; examples: Alhambra, NV; Wharf Resources, S.D.Treatment of pond reclaim water to prevent either ""preg-robbing"" or depression of gold-bearing pyrite in a flotation step; example: Getchell, NV.Treatment of backfill to prevent possible groundwater contamination; example Hope Brook, Nfld.Treatment of tailings ponds to prevent bird kills; example: Paradise Peak, NV.""Emergency"" units to deal with unusual events such as freak storms or dam failures."

Jan 1, 1989

By M. A. Amarante

Beneficiation studies were conducted on a Portuguese feldspar ore, in order to obtain final products capable of being used in the ceramic industry. A simple scrubbing operation is enough to break the lumps in the feed. The ore deposit contains ca 35 x 106tonnesfrom which, by screening, three main products could be obtained. This paper focuses on the beneficiation of the 500/74 µm fraction, which constitutes about 27% of the ore, assaying 9.42% Al2O3,equivalent to approximately ca 46% feldspar, with a mean iron content of 0.29% iron oxides. Magnetic separation and froth flotation testwork was carried out, in order to decrease the iron contamination and increase the feldspar content. Magnetic separation alone decreased the iron content of the feed to values between 0.04 and 0.08% iron oxides with an average yield greater than 90%. Flotation with HF, provided a feldspar recovery of 45?46% with a concentrate assaying 17.6% Al2O3. The use of H2SO4, gave a recovery of 35?36% of feldspar concentrate, assaying 16.1% Al2O3. However, economic and environmental advantages of using sulphuric acid may compensate for the lower mass recovery. The iron content of0.12% iron oxides in these concentrates, could be reduced to 0.04?0.05%, by further magnetic separation.

Jan 1, 1997