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Sandsloot open pit is situated on the northern limb of the Bushveld Complex, 250 km north east of Johannesburg, South Africa. Sandsloot is currently the largest open pit platinum mine in the world and is one of six potential open pits in the area. The geotechnical strength properties of the Platreef have posed significant mining and processing challenges to the PPRust operation since inception in 1992. In order to optimize the whole business as opposed to isolated cost centres a mine to mill initiative was embarked upon in 1997. Initial work focused on ore characterization and an entire suite of data was collected for each rock type. This included mineralogy, geochemistry, geotechnical, blast ability indices, as well as metallurgical strength data. The second phase involved the clear definition of customer requirements, namely the optimum performance criteria for the plant and mining departments. This involved extensive field trials and data capture to measure the interaction and influence of the mine to mill value chain. Once the design targets were defined, a 3D geotechnical model was constructed to ensure that the targets were consistently achieved. The model is very similar to an ore reserve model; however, it is populated with geotechnical, metallurgical and blast index data. Through software queries the appropriate blast powder factor for each mining block can be obtained, thereby ensuring the correct fragmentation is blasted for the plant and mining operation. The initiative has delivered significant results showing improvements across the mine to mill value chain. These include increased loading rates, reduced electricity and crushing consumables, as well as higher plant throughput. Additionally, the initiative has benefited both brownfield and greenfield projects on the PPRust operation

Jan 1, 2006

By F. A. Camisani-Calzolari

The latter half of the 20th century has seen the proliferation of a series of codes to address commodity needs which were brought about by rapidly advancing technologies and the globalization of markets and consumerism. This paper addresses the specific needs and the origin of this surge and presents these codes in the context in which they were developed. It also compares the main codes or groups of codes and elaborates upon their strengths and weaknesses. Three main categories of codes are identified, namely codes for reporting to international agencies, codes addressing government needs and, finally, codes for the investors and the stock market. Codes governed by international agencies usually relate to strategic commodities which have highly specialized fields of usage such as nuclear power generation where international cooperationis eventually the only viable approach for both the development of technologies and their applications. Codes for reporting to governments address the necessity of each state to exploit its mineral potential profitably and to secure the preservation of wealth for future generations. Reporting to investors is experiencing a considerable popularity as of late because of globalization in mining and the growing need for outside financing of mining projects, whose capital requirements are getting out of reach for the average mid-cap mining company. All these codes have advantages and shortcomings dictated by the specific circumstances under which they were developed, therefore necessitating the definition and implementation of some kind of international standard whereby investments and the spread of information across political boundaries would be facilitated. Though none of these codes might ever become international in the true sense of the word because of significantly different legislations at national level, a step that would greatly contribute to the cross-border disclosure of information would be the reciprocal recognition of competent persons by the major mining countries, including China and Russia. It is also becoming essential that financial institutions and investors be properly advised on mining projects by reporting reserves and resources in a transparent and responsible way with the relevant public disclosures being compiled by professionals who take full responsibility for their submissions. Keywords: reporting codes, mineral resources, mineral reserves, competent person, UN Framework Classification, IAEA classification, JORC Code, SAMREC Code and CRIRSCO.

Jan 1, 2004

By Fadeela Saloojee, Frank K. Crundwell

"Pressure leaching is an option for copper recovery from chalcopyrite. Leaching takes place at high temperatures and pressures in the presence of an oxidising agent. This work shows how the performance of pressure leaching circuits may be improved by optimising the configuration of autoclaves and the heat-removal method. The objective was achieved by creating an autoclave model by combining mass balances, energy balances and population balances. A base-case circuit consisting of a single autoclave was chosen, and this base case was compared with options for increasing capacity by adding more autoclaves to the circuit. These capacity–increase options include circuits in which the additional autoclave is added in parallel, in series and in series with thickening between the two autoclaves. The copper extraction, productivity and cooling requirements for these options are compared. The series circuit with inter-stage thickening has the highest extraction and productivity, however, the cooling duty in the first autoclave is high. In addition to comparing circuit options, three options for heat removal were investigated: cooling coils, quench water and flash recycling. The flash-recycle option results in the highest copper extraction, and the quench-water option gives the lowest copper extraction. INTRODUCTION Background Copper sulfide ores and concentrates containing chalcopyrite are typically hard to leach under atmospheric conditions. Smelting of these ores may also be a challenge, due to the inability of smelting processes to handle low-grade ores, as well as impurities such as arsenic and antimony. Alternative hydrometallurgical routes to treating chalcopyrite are therefore required. One option is pressure leaching, which is the focus of this work. In the pressure leaching process, sulfide ores and concentrates are leached in autoclaves at temperatures of 200 to 220°C and a pressure of about 3000 kPa (Schlesinger et al., 2011). An oxidising agent, usually oxygen, is required to oxidise sulfide ions to sulfate ions. The oxidation of sulfur to sulfate is exothermic; consequently, a method of heat removal is necessary in order to maintain the temperature in the autoclave."

Jan 1, 2015

The safety of mining operations is significantly influenced by the in situ stress fields in which the mining excavations are created. From the point of view of planning of mining operations, the in situ stress field is a most important input parameter for valid modelling of excavations. Many in situ stress measurements have been carried out for mining and civil engineering projects in southern Africa over the past 30 to 40 years. A database of in situ stress measurement results and observations has been compiled. This paper presents results extracted from the database which are considered to be of particular interest to mining areas in South Africa. The database will permit the estimation of likely stress conditions in new areas of mining, provide a basis for evaluation of results from future in situ stress measurement programmes, provide a basis for comparison of observed behaviour with expected behaviour, and provide a source of data on which realistic design and layout analyses can be based. The information contained in the database indicates that horizontal to vertical stress ratios in the Carletonville, Klerksdorp and Rustenburg areas are significantly higher than the value of 0,5which is commonly used in mine layout planning.

Jan 1, 1998

Elongates are commonly used as stope support in South African gold and platinum mines. To evaluate the effect of the inherent strength, stiffness and yield variability associated with elongates, a statistical method is presented which addresses and quantifies the support performance at various levels of certainty. The analysis, which is based on a normal distribution, makes use of force-deformation curves determined from multiple laboratory compression tests on the same support type. The applicability of the method is illustrated making use of actual performance capabilities of various types of elongates. In order to ensure a high probability that support units installed underground exceed the standard support performance curve established by means of laboratory tests, the statistical mean of a suite of tests based on the same support type is downgraded. The ?correction factor? is a function of the mean and standard deviation of the test data, as well as the sample size of units deemed to control the local rock mass stability. It is shown that downgraded performance curves based on a high probability (90 to 95percent) of support units exceeding this performance level are suitable to ensure that the design of support systems will in variably meet the design criteria. In the highly discontinuous hangingwall rock mass typically associated with intermediate- and deep-level mining operations, the interaction between adjacent support units is comparatively limited (at the support spacings commonly used). Therefore, the appropriate sample size (n) of the support units controlling the local rock mass stability should be n= 1. In shallow mining conditions, sample sizes of up to n=5 may be warranted, depending on the spacing of joints and other discontinuities in the hangingwall.

Jan 1, 2001

By M. Hopf

The use of water-cooled copper components as sidewall elements of submerged arc furnaces and other pyrometallurgical applications has become increasingly common. The high cooling efficiency of copper has made it possible to increase the service life of furnace refractories when compared to conventional refractory linings. However, even the self-healing effect of ?freezing? worn areas of the lining does not necessarily protect the copper coolers against wear or corrosion completely. In order to avoid furnace explosions, various methods have been used to monitor the wear of coolers. Unfortunately, these have not been able consistently to identify localized wear. Thos Begbie (South African) and SAVEWAY (German) jointly developed technology to embed a line sensor into the copper cooler during the casting process. This system allows an exhaustive monitoring of the copper cooler. A SAVELINE sensor is placed inside the copper-cooling panel between the water-cooling passage and the hot face of the panel. The sensor follows the meandering shape of the cooling water channels. In the first instance, the sensor provides analogue information as the thickness of the copper reduces. Secondly, this wear signal will be confirmed by a signal of interruption if the sensor is washed away. Because of the structure of the sensor, a self-diagnosis is possible and indications can be confirmed (double proofed).Subsequent to the manufacture of some test pieces, coolers for a large submerged arc furnace were manufactured. The sensorized coolers have been installed at the intermittent surface (slag line) where the largest amount of corrosion has been encountered. The system has been operating since December 2005 in what is considered one of the largest submerged arc furnaces in South Africa. Keywords: Pyrometallurgy, furnace, copper coolers, freeze lining, monitoring, Saveway

Jan 1, 2006

By C. van Tonder

Paper written on project work carried out in partial fulfilment of B Tech (Engineering Metallurgy) degree This investigation relates to a multi-purpose electrolytic system. Its primary purpose is to electrowin gold from high or low concentration gold cyanide solutions and/or from gold sludge, and to convert the recovered gold into a gold (alloy) electroform or electrode at the gold mine itself. These operations are carried out sequentially and in situ in the same electrolytic cell. Electrorefining of the gold recovered may also be done in the cell. The system applies to silver as well, and may be adaptable to base and platinum group metals. It could also be used in environmental applications, to remove undesirable metals present in aqueous solution at very low concentration. The work to be discussed forms part of recently filed patent applications. Subsequent and future developments of the system are briefly outlined. This paper, in part or in full, has been published by the Metallurgical Mine Managers Association (MMMA), with permission from the authors.

Jan 1, 2006

By L. Joncourt, N. Touchard, G. Pochart, C. Perdon

Worldwide, the major Manganese ores can be separated into three different types: ?Oxidized ores (MnO2): in Australia, Gabon, Brazil,?. ?Semi-oxidized ores (Mn2O3): in South-Africa, Australia,?. ?Carbonated ore (MnCO3): in Ghana, South Africa, Kazhakstan?. The other Manganese ores are less rich but can be used locally or in the neighbour countries (China, Ukraina, India?). Since the beginning of the 20th Century, Manganese has played a big role in the steel industry process average usage ratio: 9,5 kg/mt of steel). The recent grow-up of this industry has led to an increase of Manganese ores demand. In parallel, several companies have increased their Manganese ore producing capacity. In this presentation, we explain the link between the main Manganese ores characteristics and the key different factors for an effective and low cost Mn alloys production (HCFeMn and SiMn): ?Chemistry ?Size ?Reactivity Then we will point out the advantages of Comilog ore and Sintec ® usages in various Manganese alloy metallurgical process compared with the other main ores and with the local ores. Some advised formulations for the different kinds of furnaces and alloys will be also discussed.

Jan 1, 2007

By J. H. Zietsman

It has previously been observed that industrial high-titania slags display a compositional invariance, remaining close to stoichio-metric M3O5. The present study focuses on this invariance and the phenomena which may cause it. The invariance was studied using thermochemical calculations and a mechanism is proposed for the observed behaviour. The mechanism suggests that a combination of thermochemical equilibrium and transient slag solidification and melting results in the observed compositional invariance. The proposed mechanism provides new insights and prompts questions about other mechanisms in the smelting process.

Jan 1, 2004

By F. T. Cawood

Inauguration of the new political dispensation in South Africa in1994 initiated a dynamic shift in the ownership, management and development of the country?s affluent mineral heritage. The process of substituting the old South African regime with a new equitable system started soon after the 1994 election of the African National Congress (ANC) to parliament. The Congress?s Freedom Charter revealed the intent of the new dispensation when it called for radical transformation of mineral development. However, since then there have been important changes affecting the rules of mineral development. These are: ?A drastic change in politics ushered in by negotiation, a spirit of reconciliation and a desire to settle disputes peacefully ?The globalization of the South African mining industry in tandem with the opening of domestic mineral resources to foreign capitalists and ?The introduction of sustainable development as a holistic approach to mineral development in order to replace traditional narrow-minded environmental management. Each of these significantly shaped the new mineral investment environment of South Africa. This paper represents a summary of the historical developments leading to the current Mineral and Petroleum Resources Development Act No. 28 of 2002, its regulations, the much publicised Broad-Based Socio-Economic Empowerment Charter, its associated Scorecard, and the Draft Royalty Bill.

Jan 1, 2004

By G. de B. van Niekerk

This paper briefly outlines some mining technology that is used with success in Australia but is not yet fully utilized in South Africa. The following aspects are discussed: improved rotary-drill bit performance, use of trucks and load haul- dump units underground, long-hole raising, blasting techniques, and the use of butterfly roofbolt plates for support.

Jan 1, 1989

By A. Vorster

The objective with mine planning is to consistently deliver production conforming to quality and quantity requirements throughout the life of the mine. The complexity of the operational context of the modern mine extends far beyond the actual production actions and there is a need to find ways of analysing and managing this extended environment. A well-established approach to handling complex situations rely on the creation of representative models that use classification and visualization strategies. An example of the use of a classification scheme is the periodic table of the elements. All physical matter can be expressed as combinations of basic elements. Not only is the periodic table useful in classifying and identifying matter but it can also be used for the prediction of the properties of unknown matter and compositions of elements.

Jan 1, 2001

By B. P. Watson

Several large falls of ground occur annually in the narrow, tabular stopes mined in the Bushveld Complex. These falls comprise safety risks and cause substantial production losses and compromise efforts to increase productivity. Underground observations in conjunction with instrumentation sites were used to establish the strategic parameters required to describe the rock mass behaviour of shallow-dipping stopes on the Bushveld platinum mines. Existing rock mass rating systems were evaluated using the observations and instrumentation results. None of the current systems adequately described all the relevant geotechnical conditions. Thus a hybrid of several current systems was developed, and the proposed system is discussed in the paper. The new rock mass rating system is termed the ?New Modified Stability Graph? system and follows the method originally described by Mathews et al.1and revised by Hutchinson and Diederichs2.Changes have been made to some of the tables provided by Barton3and to the stress analysis suggested by Hutchinson and Diederichs2. In addition, the logistical regression analysis has been applied to databases, formed using the suggested analyses, for three support resistances and risk levels established.

Jan 1, 2004

A number of impending and actual pit wall failures have been observed and documented, which have been interpreted to initiate on newly generated structural features. This infers failure through intact rock. Failure mechanisms have been postulated resulting from circumferential stress, extensional strain and brittle flexure. These will be discussed in the context of the failures and the associated monitoring. The implications of failure initiating on ?unknown? features has a significant impact for deep open pit mines where designs are based on the expected structural regime. Being able to anticipate such failures is important for design. Equally important is management of such changes as they arise. In this context, monitoring using high resolution microseismic techniques will be discussed as a means of providing early warning of such failures.

Jan 1, 2006

By D. J. Fourie

During the production of pure TiO2for the pigment industry, ilmenite, containing 35?60% TiO2, is reduced to high titania slag, containing 70?95% ?TiO2? and pig iron. The high titania slag produced, consists mainly of titanium in different oxidation states and FeO in equilibrium with liquid iron. To predict the phase and chemical reaction equilibria in a furnace, a suitable solution model is required with accurately determined binary interaction parameters, as slag melts tend to behave very non-ideally. This paper investigates two popular slag models, namely, modified quasi-Chemical (MQC) model and the cell model and provides the binary interaction parameters based on recently published data of the ternary system and critically assessed published unary and binary data. Very few modelling results have been published on the ternary Ti-Fe-O system pertaining to high titanium slags. The solution models, with their regressed interaction parameters, can subsequently be implemented in commercial software of the slag-metal phase equilibria to predict how much and which type of solids will precipitate for a given bulk slag chemistry and operating temperature or, alternatively, above which temperature should a furnace be operated to avoid excessive solids precipitation.

Jan 1, 2005

By Mark Van Kleek

CONTENTS ?The Falcon C ?Data from a Production Trial ?Methodology ?Scale-up ?Test Results ?Circuit Configurations ?Conclusion

Jan 1, 2006

This paper summarizes the results from a project aimed at adapting scroll centrifuges for application to the dewatering of flotation concentrates. The main impetus for the project was to reduce the high cost and footprint size of the technology currently used to dewater fine coal. The technical challenge was to enhance solids capture by incorporating a laser-cut screen into the design of the basket. The project has shown that a pilot-scale scroll centrifuge can be used to dewater froth concentrate. A number of different basket designs were tested, the best results being achieved with a basket comprising a laser-cut screen of aperture 70 µm. The best result on a sample of untreated flotation concentrate, which was taken from the open trough flotation cells at a coal preparation plant (CPP) in NSW was a solids recovery of 82 wt% at a product moisture of 24.3wt%. By comparison the best product achieved with a conventional wedge wire basket was a similar moisture content but solids recovery was only 64 wt%. This could only be achieved after the feed had been artificially thickened. Conditioning of the centrifuge feed with polymer flocculants led to an increase in recovery up to 88 wt% with a moisture content of ca 25 wt%. It is thought that optimizing additive selection and conditioning parameters, as well as screen aperture and open area, could improve performance still further. The results were obtained using centrifuging conditions (centrifugal force, feed solids, feed rate) in the pilot-scale machine which should be possible to translate into conventional designs of commercial scale machines, without downgrading solids throughputs. However only with full-scale trials will it be possible to establish this assertion with certainty.

Jan 1, 2001

This paper provides an overview of possible approaches for structuring the ventilation systems for mines that will become operational within the next decade. Features addressed in the paper include: aspects of airway design and layout in the absence of centralized vertical return shafts, the impact of using diesel-powered trackless equipment in conjunction with conveyor belts in the development and production phases of the project, and the need to balance increasing electrical power costs against the requirement for reduced capital expenditure. The paper provides brief descriptions of the strategies employed in real-life situations and presents an overview of various operational parameters affecting the design of ventilation systems that will be used as ?platforms? for much deeper mines in the future.

Jan 1, 2007

By A. M. Hearn, J. R. Henning, A. S. J. Van Rensburg

The lining, together with the electrodes, forms the heart of the operation of a submerged arc furnace. Subsequent to a lining failure on M12 furnace during the early 1980s, Metalloys was active in investigating the concept of thermally efficient ?freeze? linings for its furnaces. The theory revolved around that, not only would, thermally efficient linings result in significant cost savings, but they would also last longer as a result of being subjected to less harsh operational conditions. After having proved the concept on the .smaller. furnaces, Metalloys decided to implement the concept on its largest submerged arc furnace, M12 Subsequent to having recovered from an impending failure of a lining installed in 1981 in M12 in the mid 1980s, Metalloys managed, through rigid lining management, to extend the life of this lining to 1999. At the end of 1999 the decision to replace the lining in the furnace with a ?freeze? lining was made and planning and design proceeded in earnest. This paper discusses the options considered in making the final decision. The features of the design of the lining are also discussed. Consideration is given to the furnace shell cooling system as a result of its importance in maintaining the thermal equilibrium in the lining. Note is made of the fact that the purchase of a .freeze. lining is an expensive exercise but that the time savings in the installation of the lining and the efficiency improvements during operation far outweigh the additional capital cost. The experience on M12 has been that the payback period of the marginal capital expenditure is less than three years. As a result of the opportunity to reline a furnace the size of M12 not presenting itself very often, the learning points from the installation of the lining and the operational advantages and disadvantages are significant. Finally, the point is made that the project had its pros and cons but overall the success of the project has been evident and, as such, the ?freeze? lining is likely to become the norm at Metalloys.

Jan 1, 2004

By J. D. Steenkamp

In a paper presented at the Heavy Minerals Conference 2001 a laboratory scale investigation on the beneficiation of an ilmenite containing waste stream by magnetizing roasting was reported1.This waste stream contained a high concentration of ilmenite, which was contaminated by chromite and other gangue minerals. Interpretation of the results of the investigation was based on the assumption that during magnetizing roasting of an ilmenite concentrate, under the oxidizing conditions, the magnetic properties of the chromite would remain constant. In this article the following hypothesis was tested: The magnetic susceptibility of chromite would remain constant during magnetizing roasting of an ilmenite concentrate under the oxidizing conditions reported by Gouws and Van Dyk1. The results of this study indicated that the hypothesis is not true. The increase in the magnetic susceptibility is not significant though and it is expected that it will not influence the final ilmenite quality to a large extent. Based on the assumptions that the bulk magnetic susceptibility of the waste stream samples represents that of the ilmenite in the waste stream, and the bulk magnetic susceptibility of UG1 chromite that of the chromite in the waste stream, the results also served to confirm that the waste stream with a high chromite content should be roasted under oxidizing conditions, in a reactor with a well-defined retention time distribution (i.e. a fluidized bed reactor), at a roasting temperature of 750°C (rather than the higher temperature ranges of 800°C and 850°C).

Jan 1, 2003