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The 103rd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 16th August, 2000. Welcome The President extended a special welcome to the guests and representatives of our sister institutes and other associations. Also to recipients of awards, senior members of industry, Honorary Life Fellows, Past Presidents, our Members and other guests, among them the following: Reinie Meyer, President, The Geological Society of South Africa Dr Nielen van der Merwe, Chairman, The South African Institute of Rock Engineering Chris Fourie, President, Institute of Mine Surveyors of South Africa

Jan 1, 2000

By J. E. McGill

The junior and small-scale mining sectors in South Africa play an important role in the livelihoods of numerous communities. Mining presents an opportunity, in the post-1994 democratic era, for many individuals to obtain access to much required empowerment and socio-economic development. These sectors are, however, not without numerous characteristics that pose problems for operators, legislators, and other role-players. Mining is inherently risky, with operators experiencing frequent difficulties and challenges throughout the life of mine. Opportunity exists, and needs to be enhanced, for junior and small-scale prospects and operations to include technical risk assessment techniques in documentation presented in search for funding, and in optimizing monthly planning and longer-term functioning. The focus here is to explore how the risk management cycle may currently be applied to a mineral resource suitable for exploitation by the junior and small-scale mining sectors. No management process can create additional value in the ground, but various available mechanisms can go a long way to quantifying the inherent risk that exists, highlighting the need to manage the risks and hopefully allowing the entrepreneur access to the intrinsic opportunities of the emerging mining sector in South Africa.

Jan 1, 2006

By J. F. Curtis

In the synopsis, the author concludes that ?high levels of seismicity do not coincide with high rockburst rates?. Implicit to an appreciation of this statement is the necessity of a common understanding of what is understood by the terms: ?high level of seismicity? and ?high rockburst rates?. With respect to the former term there is no difficulty in that the level of seismicity is traditionally measured in terms of the Richter Scale. The latter term however presents a problem in that the author defines it as a particular sort of seismic event?viz: ?Rockburst? is understood as a seismic event that causes damage to an underground excavation with subsequent injury, loss of material/equipment or production shifts? (p. 322). No scale is given of the amount of: ?excavation damage ?level of injury ?material/equipment loss ?production shifts lost whether separate or cumulative, for a particular seismic event to be classified as a rockburst. A further difficulty arises in that in common usage the words ?rockburst?, ?seismic event? and ?earthquake? are all used to describe the same event.

Jan 1, 1999

By D. G. Krige

For the purpose of determining confidence limits for ore grade estimates, an extensive simulated data base was used, which included 1728 ore blocks with ‘actual’ grades and the corresponding estimates based on ordinary and simple kriging. The practical results show that conditional unbiasedness is essential and that acceptable confidence limits can then be set using Normal theory for the simulated error distribution based on the logarithms of the ratios of ‘actuals’/estimates with a variance related to the kriging variance. The mean of the data used to prepare the variogram and the estimated block grade are to be used properly in this approach. A practical analysis was also done of the actual point and block data from a very large mined out Carbon Leader area. The distributions of the actual grades for two levels of block sizes with different levels of variability were fitted using three models, ie. 2-. 3- and compound-lognormal. The trends of tonnages, grades and relative profits for a range of pay limits, as well as the usual tonnage-grade curves, show a practical insensitivity for the choice between the three lognormal models considered.

Jan 1, 2003

By R. T. Jones

Slags have been produced as by-products from pyrometallurgical processes for thousands of years, and have generally been regarded as waste. Many of these slags are no longer seen as residues merely to be discarded, but as potential economic sources of metals, or as useful by-products in their own right. Slag cleaning can enhance the recovery of valuable metals in existing pyrometallurgical processes, or can produce economic value from recycling old slag dumps. For example, a process has been developed and implemented industrially for recovering cobalt from copper smelting slag in a DC arc furnace. The relatively non-leachable behaviour of glassy slags allows them to be used as a very safe means of disposal of metallurgical waste streams, including many that are classified as hazardous. The high temperatures, reducing conditions, and good mixing that can be achieved in a DC arc furnace enable the effective functioning of this environmentally beneficial means of disposal. Lead blast furnace slag can be rendered safe for disposal by treating it using the Enviroplas process, which strips most of the hazardous lead from the slag (and traps the rest in an insoluble glassy slag) and recovers economic quantities of zinc by absorbing (in a lead splash condenser)the zinc vapour that is fumed off in the furnace. Another example can be seen in the recovery of a chromium- and nickel-containing alloy from stainless steel plant dust, while producing a disposable residual slag. The examples presented here illustrate that it is possible to develop processes that are both economic and environmentally beneficial. Keywords: DC arc furnace, plasma, slag cleaning, cobalt recovery, zinc fuming, Enviroplas, jigging, re-melting fines, environmental, economic

Jan 1, 2004

By G. Wendel

Uranium is a naturally occurring radioactive material in the earth?s crust. Geological processes have resulted in concentration of uranium into ore mined for its gold content in South Africa. This uranium is present in the form of discrete particles of uranium minerals, generally oxides, which are normally insoluble. Chemical and physical processes during gold mining and extraction, particularly when carried out in conjunction with uranium extraction and sulphuric acid manufacture, act on the uranium minerals and the radioactive decay products of uranium. This may result insignificant accumulations of radioactive materials in certain parts of the process. There are a number of naturally occurring radioactive materials in the earth?s crust, such as Uranium-235, Thorium-232, andPotassium-40. This paper focuses on Uranium-238, together with its decay products, and how they affect the gold mines. Water plays a significant role in the redistribution of radionuclides, both as a physical transport medium, and as a solvent in which chemical reactions take place.

Jan 1, 1998

By R. Pickering

The purpose of this paper is to explore the application of technology to stoping systems. Technology, because for the past 100 years the South African narrow reef mining industry has battled to control working costs in a labour-intensive industry. Stoping systems, because it is the stoping method and methodology which is at the heart of the mining system. Introduce a more efficient stoping system and the mining system will look after itself. The technology applied to stoping over the past 100 years can be categorized as follows: ?The introduction of pneumatic rockdrills early this century, the cumbersome rig mounted units being replaced by smaller, lighter hand-held units which were then made easier to use with the addition of an air leg ?Scraper winches to replace gravity and shovels to move rock both in the face and the gullies were first introduced in the late 1920s ?Hydraulic props as a support method arrived in the1960s ?Some people argue that tungsten carbide inserts were equally important. There have been a number of attempts to introduce different technologies into stoping, the most recent being trackless equipment. Where the stoping layout suits the technology it has been successful. There have been too many instances where a technology has been installed because it is fashionable. At the end of the day the outcome from change in the stoping systems has to be safer and more profitable mining systems. It is the contention of the author that change is only likely to be effective if it is supported by the introduction and application of appropriate technology.

Jan 1, 1999

By Manuel Rapiman, Ricardo Sepulveda

The feasibility study of Escondida Norte (ENorte), recommended a slope angle design for the Final Pit. But, according to the experience obtained with the slope adjacent to the West wall of ENorte, in which Compañia Minera Zaldívar (CMZ) gained in its phase 4, a slope of similar geotechnical characteristics will be exposed in the West Wall of Phase 1 (Premine) and of the Final Pit, with an interramp angle 53º and with very good stability results. In this regard, Minera Escondida Ltd. (MEL) performed a study of the slope angles for the phases mentioned and according to this delivered the results of this evaluation, the recommendations and/or the necessary conclusions in the design to ensure that the slopes are stable enough and may enable safe operational management of them.

Jan 1, 2006

A large number of brittleness concepts have been used in very different studies in the literature. One of them is the B1brittleness concept. In this study, the objective is to criticize the B1 brittleness concept on rotary blast hole drills. The B1 brittleness concept, the ratio of uniaxial compressive strength (sc) to tensile strength (sT), are widely used as a rock brittleness concept in the literature (Inyangand Pitt, 1990; Verhoef, P.N.W. 1993; Neil, D.M. et al.1994;Becker, et al.1984; Evans and Pomeroy, 1966; Göktan, R.M.1992; Kahraman, S. 2001; Yamaguchi, U. 1970; Verhoef, P.N.W. et al.1996; Bilgin, 1982; Howarth and Rowlands,1987; Howarth, D.F. et al. 1986). So, it was used as a rock brittleness concept in this article. The value of the B1brittleness concept is equal to the tangent of ß angle in the following graph. It was seen that more meaningful relationships could be obtained with the B2 brittleness, the under ?Area?(= 1/2(scxsT) = B2) under the curve, instead of tangent ß, (=B1), of the curve.

Jan 1, 2003

By X. Pan

Slag-metal equilibrium experiments were conducted at 1500ºC and 1580ºC under 0.03 atm, 0.05atm and 0.83 atm CO partial pressures using silica and Cr-oxide crucibles. The complex slags belonged to SiO2-CaO-Al2O3-MgO-FeOx-CrOxand the metal phase to the Cr-Fe-C-Si-(S)systems. The carbon saturation of the metal phase was avoided using oxide crucibles and thus the results are pertinent to ferrochromium refining slags and processes. From equilibrium data and thermodynamic calculations the CrO /(CrO+Cr2O3) ratio in the slag was determined as 0.75, 0.80and 0.86 under 0.83 atm and 0.05 atm of CO pressure at 1500ºC and 0.03 atm and CO pressure at1580ºC respectively. The results clearly demonstrated that a higher chromium content of the metal results in higher Cr in the slag, and chromium in slag decreases with increasing SiO2. The results were also sensitive to the crucibles used as these oxide crucibles saturated the slag either with respect to SiO2or Cr-oxides. It was also demonstrated that the relative amount of CrO in the slag was higher when SiO2crucibles were used in accord with thermodynamic calculations. Iso-concentration curves for carbon and chromium of the metal phase in equilibrium with the slag were drawn on pseudo ternary SiO2–(AI2O3+CaO+MgO)–(Cr2O3+Fe2O3) diagram. The activity coefficients and activities of carbon and chromium of the metal phase were also calculated from the experimental data and available thermodynamics information and were plotted as iso-activity curves in the same pseudo ternary diagram. Keywords: Chromium, slag, equilibrium

Jan 1, 2004

By G. Konak

In-pit crusher location selection has had an important role recently, since increasing diesel prices. One way of reducing the haulage costs is to shorten the truck haulage distance by bringing the truck dump point into the pit. This study covers the work done on the optimum crusher location definition for a company that produces aggregate near Izmir, a city of Turkey located in the west. This paper will discuss the effects of pit geometry and mine access requirements on optimum crusher location selection that are mainly based on the establishment of minimum haulage distance. The method will be introduced first and then the computer algorithm developed for this study will be discussed later in the paper. Keywords: in-pit crushing, optimum location selection, optimizing haulage, computer aided design.

Jan 1, 2007

The 100th Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 13th August, 1997. Obituaries The President announced the death, during the year, of the following members: Honorary Life Fellows and Past Presidents D.M. Jamieson, V.C. Robinson Fellows S. Goodwin, M.W. Johns Retired Fellows T.F. Muller, P.L. Nathan, N. Orsmond, R.J. Ortlepp, H.S. Sichel, K.E. Steele, W.B.L. Steuart, N.B. Vinson Member J.P. Hatfield Retired Members S.T. Baron, B.F. Pinder Retired Associate F.J.A. van Reenen In memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1997

By D. M. Mubita

Dilution reduction is one of the areas that offer metal mines an opportunity to increase revenue and reduce costs, resulting in enhanced profits. Effective dilution control programmes require interaction on a multi-disciplinary level. This paper outlines recent initiatives undertaken at Konkola Mine to reduce dilution and increase revenue. The increase in revenue arising from reduced dilution and high factors between in situ and delivered to mill grades were quantified and amount to close to U$ 1.0 million per one per cent improvement in grade factor at a 75c/lb copper price. Sources of dilution from open and in?stope mining methods practised at the mine were identified and a multi-disciplinary dilution control forum set up to control these. Among the major achievements were the introduction of low dilution in-stope mining methods; the introduction of Gemcom geological and mining planning software to replace traditional pencil and paper methods, leading to better in situ estimation and production planning; enhanced control in open stopes through dilution awareness among mining production personnel; location of critical secondary development ends in correct positions; enhanced blast hole control; tracking of development waste by metal tracers and monthly tally; implementation of a cavity monitoring system to check over-breaks in open stopes; and setting up of a stope history database. The results from the cavity monitoring system showed that stopes with over-breaks of 5 metres or less could be controlled to break along the hangingwall contact.

Jan 1, 2005

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements of The South African Institute of Mining and Metallurgy set out on pages 451 to 460 for the year ended 30 June 2002. These financial statements are the responsibility of the Institute?s Council. Our responsibility is to express an opinion on these financial statements based on our audit. Scope We have conducted our audit in accordance with statements of South African Auditing Standards. Those standards require that we plan and perform the audit to obtain reasonable assurance that the financial statements are free of material misstatement. An audit includes: ?examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, ?assessing the accounting principles used and significant estimates made by management, and ?evaluating the overall financial statement presentation. We believe that our audit provides a reasonable basis for our opinion. Audit opinion In our opinion, the financial statements fairly present, in all material respects, the financial position of the Institute at 30 June 2003 and the results of its operations and cash flows for the year then ended in accordance with South African Statements of Generally Accepted Accounting Practice. Auditors 29 July 2003 Council?s approval of the annual financial statements The annual financial statements for the year ended 30 June 2003 set out on page 451 to 460 were approved by the Council on 26 July 2002 and are signed on its behalf by:

Jan 1, 2003

By S. Kitamura

In recent years, the amount of ferritic stainless steel production has increased. However, the rust formation by the salt spray test was pointed out in the past. At the centre of the circular rust zone, pitting corrosion where water-soluble nonmetallic inclusions were embedded was observed. These inclusions originated from the suspended refining slag and consisted of multi-phase oxides and sulphides. By the experiments and thermodynamic consideration of the water-solubility, not only CaO or CaS, but also lime rich calcium-aluminates or calcium-silicates have shown large water-solubility. The composition of oxide phase in the inclusions was almost the same among the samples from molten steel, slab, or cold rolled sheet. On the contrary, CaS was clearly observed around the oxide in the sample of cold rolled sheet, although it was not found in the molten steel or slab samples. The enrichment of sulphur occurred from the desulphurization reaction of the suspended slag particles in the molten steel and also occurred from the diffusion of sulphur to the oxide inclusions during the heating of the slab. The optimization of refining slag composition has lead to produce the ferritic stainless steel without rust formation. Keywords: stainless steel, rust, calcium aluminates, calcium sulphides, water-solubility, refining slag, composition control of inclusions.

By Sylvie Poirier

Researchers at Natural Resources Canada (NRCan) CANMET Mining and Mineral Sciences Laboratories (CANMET-MMSL) and Mining Technologies International (MTI) have designed and built a hybrid diesel-electric mining loader that is the first of its kind to be developed for underground mines. Diesel equipment is popular because of its mobility and most mining operations are reluctant to replace it with tethered electrical equipment despite the obvious elimination of diesel contaminants and significantly lower heat generation (? 35% of an equivalent diesel). However, a diesel-electric vehicle, being currently evaluated by CANMET-MMSL, could be beneficial. In this unit, a constant load diesel generator feeds batteries which, in turn, powers electrical motors that drive the equipment. In a hybrid diesel-electric unit, the constant load diesel generator can be optimized for minimal emissions and hence lower dilution air requirements. This paper will present the project status and the anticipated benefits for mining operations through the application of this technology.

Jan 1, 2008

A South African gold mining rock-related fatal accident database has been analysed in order to determine rock-related fatality trends in the gold mining industry over the period 1990 to 1998. This analysis was extended further to include some of the individual reefs mined and focused particularly on the Carbon Leader Reef, the Ventersdorp Contact Reef, the Vaal Reef and the Basal Reef. Rock-related accident locations are also presented. A stope rock-related risk is proposed, where the fatality rate in terms of rock-related fatalities per million square metres mined for the gold mining industry as a whole is compared to individual reefs, allowing a stope rock-related risk to be attributed to the individual reef. This comparison is extended further by removing the contribution by the reef being evaluated from the industry data, thereby allowing this reef to be directly compared to the rest of the industry with respect to a stope rock-related risk.

Jan 1, 2001

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

Cokriging uses a sparsely sampled, but accurate and precise primary dataset, together with a more abundant secondary data-set, for example grades in a polymetallic orebody, containing both error and bias, to provide improved results compared to estimation with the primary data alone, as well as filtering the error and mitigating the effects of conditional bias. The method described here may also be applied in polymetallic orebodies and in other cases where the primary and secondary data could be collocated, and one of the data-sets need not be biased, unreliable, etc. An artificially created reference data-set of 512 lognormally distributed precious metal grades sampled at 25×25 m intervals constitutes the primary data-set. A secondary data-set on a 10×10 m grid comprising 3200 samples drawn from the reference data-set includes 30 per cent error and 1.5 multiplicative bias on each measurement. The primary and secondary non-collocated data-sets are statistically described and compared to the reference data-set. Variograms based on the primary data-set are modelled and used in the kriging of 10×10 m blocks using the 25×25 m and 50×50 m data grids for comparison against the results of the cokriged estimation. A linear model of coregionalization (LMC) is established using the primary and secondary data-sets and cokriging using both data-sets is shown to be a significant improvement over kriging with the primary data-set alone. The effects of the error and bias are filtered and removed during the cokriging estimation procedure. Thus cokriging using the more abundant secondary data, even though it contains error and bias, significantly improves the estimation of recoverable reserves.

Jan 1, 2014

By C. Dixon

The Abandoned Mine by C.C. Woollacott A heap of rocks marks the abandoned mine. The veld's unpitying silence lies around. Those broken stone?a mute and mournful sign Of human enterprise with failure crowned. Time with the slow hands, shall form the scene anew, Repair the gashes in the wounded soil, And cover up the last remaining clue To a poor useless record of men's toil. And this, the mound they built when hopes were high Shall be a grave, where those hopes buried lie. Outline This paper will consider the implications of the mine closure provisions set out in the new Mineral and Petroleum Resources Development Act and draft regulations. A comparison will be made with the existing provisions in the Minerals Act and the mine closure policy of the Department of Minerals and Energy (DME). The paper will consider whether the new provisions have the potential for improving performance as regards mine closure. It will investigate the financial provisions requirements and the implications of these provisions for mines. It will consider the requirements for a social and labour plan and consider the implications of this for mine closure and its funding. It will analyse the provisions relating to the transfer of environmental liabilities to third parties and consider the implications of this in the case of closing mines and non-closing mines. Finally it will consider the issue of residual legal liability of a mining company once a closure certificate has been issued.

Jan 1, 2003