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By P. Goosen

The paper presents a basic summary of the approach to hydraulic scale-model tests as may typically be applicable to slurry flow situations. A case study is presented illustrating how hydraulic scale-model tests can be of significant benefit in evaluating the performance of novel or unproven slurry handling equipment. In this case the equipment tested was a fan-shaped expansion piece used to spread the discharge from a launder over the full width of a dewatering screen. The tests showed that the device did indeed distribute the slurry flow both in terms of volume and solids mass, but not perfectly uniformly. Unfortunately the equipment was not taken beyond the model test phase. The scale-model test approach did, however, prove to be very useful as it is considered to have provided a good indication of the expected performance of the full-size unit. Significantly, this was achieved at very low cost compared to the cost of installing the device into the proposed plant and having to later change it out for an alternative or live with the less than optimal performance. The paper illustrates the value that can derive from applying hydraulic scale-model testing techniques to evaluating the performance of new or unusual slurry handling equipment. There is particular value in situations that do not lend themselves to numerical modelling.

Jan 1, 2007

By R. Gurung, S. Asokan, Ch. V. G. K. Murty, R. Upadhyay

Tata Steel Limited which is Asia?s first and India?s largest integrated private sector steel company, as part of its vision to grow in related industries is also undertaking the Titania project. The project will involve mining, separation of ilmenite and other valuable minerals from the inland heavy mineral sands deposit in the Indian state of Tamil Nadu. The raw material will be beneficiated to synthetic rutile, titanium dioxide pigment and ultimately to titanium metal. The recently concluded feasibility study revealed that the deposit under consideration has 10.4%of total heavy mineral content and 15.2% slimes of the size below 63 µm, over an average sand thickness of 6.9 metres. The presence of about 15% slimes in ROM sand coupled with scarcity of water at the project site complicates the slimes handling/disposal system, requiring the development of an innovative, efficient and effective system for disposal of slimes. Mineral characteristics of slimes revealed the presence of kaolinite clay, which poses its own challenges in thickening/dewatering of slimes. This paper outlines the detailed studies conducted, including slime characterization, settling and thickening characteristics, and ge-technical studies to arrive at an efficient and effective slime handling/disposal system, with a view to plant saplings on the mined-out reclaimed land with species typically suitable to that environment.

Jan 1, 2007

By L. Dison

There are many potential uses in gold mining for an initially stiff element of backfill that will yield at a predetermined load and maintain that load to beyond a compression of 30%. Such elements could be used as yielding rib pillars, as replacements for more conventional supporting packs, as con- fining bulkheads for mass backfill, as supports to provide lateral constraint, and load-carrying augmentation to overloaded rock pillars. The paper describes a system of reinforced cemented backfill that can be used to provide the above requirements. The necessary characteristics of the reinforcing and the cemented tailings are described together with the method of design to obtain a predetermined stiffness and yield load. The load-compression characteristics of the reinforced tailings elements are described and the effect of changing various of the design parameters is demonstrated.

Jan 1, 1988

By E. Dermietzel

The fundamental ideas of Computer Aided Lignite Mining (CALM) with respect to hardware and software used at Rheinbraun are explained and outlined in detail. The computers used in the main data processing department and in the different departments in the mines are described. Special emphasis is laid upon the network connecting the computers at different places for data-exchange. Concerning technical applications, the main facilities of CALM are deposit and pit modelling, complex geomechanic computations and mass calculations, data recording from the production process in the pits and refining plants, and detailed information and planning systems for water management and mining equipment. Concerning administrative applications, the main facilities of the software are the accounting system with cost controlling and planning, the materials management system with stock control, forward planning and computer supported order procesing, a system for the administration of property within and surrounding the mines, and systems for personnel administration and payroll. The various software systems developed for these application and the influence of data processing technique, such as data base management and the interconnection of data processing systems, are demonstrated.

Jan 1, 1987

By C. P. Smyth

Large volumes of quantitative geochemical data, presenting a formidable interpretation task to geologists, are generated in the course of exploration drilling for new ore deposits. The incorporation of geological expertise into computer programs developed for the interpretation of this data would improve the speed and accuracy with which it is interpreted. A detailed analysis of the geochemical log interpretation problem, together with a survey of relevant research in Artificial Intelligence and petroleum well- logging techniques, confirms, that artificial intelligence, particularly as developed in the fields of expert systems and pattern recognition, provides techniques for implementing such data interpretation programs. In addition, it provides data analysis techniques significantly more powerful than those currently applied to geochemical data, and very appropriate to the hypothesise and test' character of mineral exploration problem-solving. The conversion of raw borehole log data to meaningful higher level geochemical entities, in terms of which geological reasoning may take place, is a critical step in applying these techniques to log data analysis. A method of achieving this conversion as an exercise in signal-to-symbol transformation is presented.1

Jan 1, 1987

By R. G. B. Pickering

The South African narrow reef hard rock mining industry has been stuck in a time warp with relatively little change in the mining process in the last century. This paper presents a methodology on how to implement change in narrow reef hard rock mining. It then explores a number of technologies that have been introduced into this mining industry and the impact that they have had on the mining process. The author then presents his view on whether the defined change process has been followed and sets out to identify the most critical aspect of ensuring that change is successfully implemented. Future demand will also be speculated on.

Jan 1, 2007

By M. M. Hajdasinski

The internal rate of return (IRR) is one of the most popular project evaluation criteria in the mineral industry, as well as in other industrial sectors. Analysis of its assumptions reveals, however, that this criterion does not function in the way it is supposed to. The search for a new criterion that would reflect the true rate of return (TRR) of an investment project or the true borrowing rate (TBR) of a borrowing project has led to the development of several approaches, yielding, for the same project, generally different values of the interest rate in question. Two of those approaches have been selected as the most representative and practical. Each has been presented in two variants, and subsequently analysed. As a result, it is shown that the various approaches to the TRR/TBR are all consistent with the net present value (NPV) criterion, and that each can serve as an independent project evaluation instrument, provided its assumptions can be regarded in a given situation as realistic enough.

Jan 1, 1987

By L. A. Abichequer

ROM grade variability is one of the most important factors influencing plant product recovery. Due to the influence of grade variability on mine profits, it is deemed important to guarantee a proper homogenization of the ore through a well-planned blending and homogenization pile system from which the ore is reclaimed at an acceptable grade fluctuation. This study tests geostatistical simulation efficiency in predicting in situ grade variability. The methodology is illustrated using a data-set from a large phosphate mine in central Brazil. Additionally, real data obtained at the mine site during January and February 2007 were used to derive the actual grades of each pile formed during this period. Each pile was formed by a selection of blocks within a dig line and these lines mined along the year 2007 were also made available. Given the real grades, it was possible to reconciliate and validate the results predicted by the proposed methodology. The main outcome of this study is the opportunity to check the geostatistical simulation as a tool to quantify the variability of the homogenization system.

Jan 1, 2009

By P. M. Vercruijsse

Dredging is an industry in constant transformation. It has changed tremendously in the last decades. The traditional dredging activity, like construction and maintaining ports and harbours, desilting of drainage and irrigation channels, keeping reservoirs at depths and removing sediments from waterways, is still of importance. However, it is surpassed by other applications of dredging technology. Reclamation is an important example, where large amounts of sand are dredged, transported over large distances and used to make new land for industrial, housing, airport and other infrastructural purposes. Beach nourishment and other protective measurements should be mentioned here as well. Other applications like offshore winning of oil and gas, environmental clean-up, mining of interesting minerals like gold, diamonds, titanium and tin as well as aggregates from inland and offshore deposits are of importance. For all of these dredging applications equipment is required, and with changing circumstances and constraints, the design and use altered significantly. Larger dredging depths and increasing capacities require an impressive scale-up of equipment and tools. A demand for higher accuracy and selectivity set the requirement for a higher level of automation and control in combination with a well trained crew. Operations under more difficult circumstances and with other soil characteristics necessitated the development of new dredging components and systems. A sound basis for all developments was and still is a better understanding of the various dredging processes. This paper will highlight some eye-catching developments in the dredging industry. It will focus on issues in the field of hydraulic transport such as ever increasing capacity and dredging depth, as well as the pumping of large size materials.

Jan 1, 2007

By E. Cetin

Orebodies that contain more than one economically important mineral are generally evaluated by parametric cut-off grades. This approach often leads to mis-valuation of mineral deposits because cut-off grades are not based on the grades of each individual mineral and, because of the parametric formulation, are only indirectly related to the individual grade distributions. The only realistic approach is a formulation that accounts separately for each component mineral. The grid search method can be used as a means of multi-mineral cut-off grade optimization in this context. This paper describes the use of the grid search method in cut-off grade optimization for multi-mineral deposits. The authors introduce the general concepts of the method and formulate its application to cut-off grade optimization; they describe a software implementation of the method that can accommodate cut-off grade optimization for mineral deposits that contain up to three economic minerals. Keywords cut-off grade, optimization, grid search, multi-mineral deposits.

Aug 1, 2013

By W. C. Joughin

A risk evaluation model has been developed, that enables the quantification of expected injuries and economic losses resulting from rockfalls associated with a support system in a given geotechnical environment. This enables the comparison of different support systems based on the expected frequency of injuries and the total cost of the support system, including the expected economic losses. The model takes into consideration the variability in joint orientations and joint strength within the geotechnical environment and the variability and quality of support systems. The quantification of the benefits of other rockfall risk-mitigating strategies, such as the effectiveness of barring or monitoring, are also incorporated in the model. The risk model is described in this paper and the validation of the model and case studies are described in Part II.

Jan 1, 2012

By B. P. Watson

In South Africa, the Bushveld platinum group metal deposits are unique in that they are the largest platinum group metal deposits in the world. These deposits occur as two distinct stratiform tabular orebodies and strike for many hundreds of kilometres. Mining is extensive, with depths ranging from close-to-surface to 2 000 m. The mining method is a variation of planar open stoping. Pillars are widely used to support the open stopes. Crush pillars are commonly used in this role, where the residual pillar strength provides the required support resistance to stabilize the stoping excavations. This paper describes the direct measurement of stress within these crush pillars, and describes the stress?strain behaviour of these pillars. These findings indicate that the measured pillar failure stress is too high. The implications of these findings are that roof damage and pillar bursting could occur, and some examples of this type of damage are shown. The paper concludes that this problem could be mitigated if the three dimensional pillar geometry were modified and the pillars were cut smaller.

Jan 1, 2007

By P. Ramphisa

In South Africa reprocessing used oil into industrial fuel is commercially attractive. The reprocessed product is sold as a substitute for heavy fuel oil that is derived from crude oil (Rose Foundation, 2008). The objective of this investigation is to evaluate the use of petroleum products such as oil, petrol and diesel in Driefontein Gold Mine. The recovery of oil through recycling has costs implications to the mine while the release of petroleum hydrocarbons due to the poor management of the use of petroleum products has potential to cause pollution and negatively affect soil and water. Environmental legislation such as the Minerals and Petroleum Resources Development Act (Act 28, 2002) requires that such negative impacts to the environment be rehabilitated. The rehabilitation cost of pollution caused by petroleum products to the environment increases operational costs in business. Field assessment is conducted to identify the main sources of petroleum product contamination such as leaks in piping, overfills and petroleum spills. The areas that require mitigation would be mapped in the study. Recommendations for mitigation measures will focus on using the best practicable environmental option (BPEO) as well as the best available technology not exceeding excessive cost (BATNEEC). The recovery of oil from the mining industry is generally low and very poor. In this study, the effect of proper management of petroleum products to the mine?s operational costs is investigated and compared to there mediation costs of the impacts caused due to poor management of these products. The study investigates the financial benefit that could be obtained from proper environmental practices and efficient usage of petroleum products in the mining.

Jan 1, 2009

By I. Ashmole

The dimension stone industry is not widely known or appreciated within the mainstream mining industry. This is in spite of the fact that the industry has grown at an average of over 7% per annum since 1980, and is estimated to now have a global turnover in excess of US$ 60 Billion per annum. Production technologies, particularly in the developed world where labour costs are high, have developed rapidly over the past two decades. Aligned with this, there has been a significant trend in adoption of a more professional mining approach in the exploration for and operation of dimension stone quarries. In fact, in the experience of the authors, mining a dimension stone deposit successfully if often more challenging from a mining engineering point of view than many conventional surface mines. This paper gives an overview of the industry and then proceeds to discuss best practice in exploration for dimension stone and to outline the latest technologies applied in mining of dimension stone. These technologies are varied and the specific combination of technologies applied in any given quarry is determined by both the physical properties of the material as well as the influence of geology which significantly impacts on the recovery of saleable material and hence the economics of the quarry.

Jan 1, 2008

By N. Sinclair

"In open pit dozer bulk push operations, the material left resting against the highwall after blasting poses an issue. This is because dozers cannot physically get in behind the waste to begin the bulk pushing process. Instead, an excavator can be used to side-cast this waste for the dozers to access. An alternative technique is to have the dozers ‘side-cut’ the material, which involves the dozers running parallel to the wall, digging out the material, and eventually rotating their blades to begin bulk pushing. Industry practices suggest the latter technique is less productive and economical than using an excavator. However, such excavator sidecasting ‘economic viability’ assumes that smaller/ancillary type excavators are used (i.e. less than 23 m3 bucket capacity). So, what happens if some mine sites are restricted to using relatively larger excavators (> 23 m3 bucket) that are preferred for higher priority digging tasks? When can they avoid using their excavator? This paper explores multiple scenarios that have been designed and developed to simulate data results, which identify conditions in which the dozer side-cutting technique becomes more economically viable than excavator side-casting in terms of decreased unit cost per loose cubic metre. IntroductionOptimizing the cost of waste removal operations is important for the profitability of opencast coal mines. In the past decade, dozer bulk pushing has emerged and taken over from traditional waste removal operations such as dragline and truck-and-shovel methods at various sites around the world (Beatty, 1994). In a typical bulk push operation, once the bench has been blasted, waste is left resting against the highwall, which can either be cleared using a loading unit or by having the dozers ‘side-cut’ the highwall.Dozers perform most effectively when slot dozing side-by-side, perpendicular to the highwall. However, when dozers are required to remove material off the highwall, they must push parallel to the highwall, rather than perpendicular, hence ‘side-cutting’ the material to ensure a clean face. While dozer sidecutting is possible, it has been found that the majority of mine sites use a loading unit in this situation to avoid dozer inefficiency. Other perceived issues with dozer side-cutting include higher maintenance requirements and safety risks to dozer operators working in close proximity to the highwall."

Jan 1, 2019

By E. M. W. Skinner

Various models of near-surface kimberlite pipe emplacement have been proposed over the years. These include a top-down, phreatomagmatic model, a bottom-up, embryonic pipe model and three top-down explosive dyke models. AU of these models consider kimberlites as essentially the same rock type. However, different kimberlites have different pipe shapes and contain different rock types with very specific mineral assemblages and textures and therefore are likely to have been emplaced by different processes. Some authors have considered local geological differences as the principal reason for the contrasting geology but others argue that, while geological differences might contribute locally the petrographic peculiarities of particular kimberlites may be due mainly to inherent compositional differences specifically in the ratios of juvenile CO2 and H2O.

Jan 1, 2010

By J. W. Neale

Mintek was a leading participant in the BioMinE project between 2004 and 2008. This project, which was funded in part by the European Commission, was aimed at the development of biotechnology for the minerals industry in Europe. Mintek?s research programme focused mainly on the development of integrated bioleach-based processes for the recovery of base metals from complex, low-grade sulphide concentrates. Specific European mineral resources were targeted and used in integrated piloting campaigns involving bioleaching, solution purification, and metals recovery. This paper describes the use of thermophilic bioleaching for the recovery of nickel and copper from a low-grade nickel-copper concentrate produced at the Aguablanca Mine in southern Spain. Currently, the Aguablanca Mine produces a bulk nickel-copper concentrate for sale to a smelter, and the proposition is to increase the profitability of the operation by the on-site production of metal or metal intermediate. Initially, bench-scale bioleach tests were conducted to determine the bioleach operating conditions. These tests included an evaluation of mesophilic, moderately thermophilic and thermophilic microorganisms. In order to achieve sufficiently high levels of both copper and nickel extraction, a thermophilic process was selected?this was necessary for leaching of the refractory chalcopyrite that occurs in this concentrate. Additional bench-scale test work was carried out to derive a conceptual process flowsheet for the solution purification and metals recovery circuit. The results of the bench-scale tests were used to design, construct and commission an integrated pilot plant, which was subsequently operated at Mintek for over seven months. During this time, the solution purification and metals recovery processes were optimized, and all recycle loops were closed. The final process flowsheet included the following unit operations: concentrate regrinding, thermophilic bioleaching at 70°C, primary iron removal using limestone, copper solvent extraction and electrowinning, secondary iron removal, nickel hydroxide precipitation using magnesia, and final solution purification using lime. Where applicable, process solutions were recycled to preserve water. The process design data derived from this pilot-plant campaign formed the basis for a conceptual engineering study for the developed process. In the study, mass and energy balances were derived, and a process flowsheet was developed and used as the basis for estimating the capital and operating costs of the process. This enabled a preliminary economic analysis of the process to be undertaken. The findings of this study are discussed.

Jan 1, 2009

By U. W. O. L Vogler

"The behaviour of rocks depends on their material properties, and therefore it is important that these properties are determined by relevant and reliable laboratory testing methods. The ISRM Suggested Methods are very important documents in this regard, and a draft suggested method exists for the determination of the ’complete stress-strain curve for intact rock in uniaxial compression’. The method specifies the required geometry of specimens and the required testing procedures. The research described in this paper involved the determination of complete stress-strain curves for two materials, one exhibiting the Class I characteristic, and the other the Class II characteristic. To obtain a better understanding of the deformation behaviours in the post-peak region, tests were carried out on specimens of both material types with different length-to-diameter ratios. The results showed that the geometries of the test specimens influence the stressstrain curves in the post-peak region. The implication is, therefore, that the numerical values obtained for the slopes of the post-peak graphs are not material constants, but are geometry-dependent. Explanations for this behaviour are given. These findings have important implications regarding the use of post-peak data, for example for blast fragmentation considerations, and for evaluation of rockbursting potential. The research findings are based on a limited amount of laboratory testing, and should be confirmed by further testing. IntroductionThe most common approach for studying the behaviour of rock is by compression testing of cylindrical specimens in the laboratory. Rocks respond to forces by deforming and eventually breaking. The strength and the deformation characteristics are derived from the stressstrain curves produced. Standard shapes and sizes for the test specimens and standard loading rates are recommended in the Suggested Methods of the International Society for Rock Mechanics (ISRM) and the American Society for Testing and Materials (ASTM) standards. In spite of these standards, there remain certain aspects of testing which require further attention. The research described in this paper deals with deformation and failure behaviour of rock materials using stiff, servocontrolled testing equipment. The particular objective was to test the premise that the behaviour of cylindrical rock specimens in the post-peak region of the stress-strain curves does not reflect only a material characteristic, but is influenced by the height-to-diameter ratio (the geometry) of the rock specimen. An additional objective was to investigate the effect of the stiffness of the test equipment on the outcomes of tests."

Jan 1, 2016

By M. Le Roux

The dewatering of coal, and particularly fine coal, continues to challenge coal prepatration engineers to find a cost-effective solution. With known world oil reserves being depleted daily, it is envisaged that the future price of coal may justify the use of thermal drying to achieve lower coal product moisture levels. The effect of exposure of the coal to elevated toemperatures on the mechanical strength of the coal was investigated. It was found that temperature does not play a major role in determining the volume breakage of a particle and that other variables such as orientation during impact has a much greater influence. A double breakage mechanism was reported during the grindability tests. Surface, as well as volume breakage, occurs for the first 4 minutes while only surface breakage takes place thereafter. Due to this double breakage action, it was found that exposure to temperature does play a role in the amount of breakage and breakage rates during grindability tests. It was also concluded that a particle will break to an optimum size due to impact, after which only its surface will grind away as it is subjected to breakage forces.

Jan 1, 2008

By Maggi Loubser

"In a technologically advanced era, where process control is accurately maintained within the smallest error margins, and accuracy and precision are continuously improved, sampling is still left to the lowest paid employee in the company without training him or her properly to understand the relevance and importance of the task. In this paper the objectives of sampling in a process control environment is discussed and an attempt is made to link it to the theory of sampling. Some of the practical problems associated with implementing theoretical sampling principles in an industrial environment will be elucidated and some examples given on how compromises are made. Different methods of sampling will be discussed with real life examples from different manufacturing industries."

Jan 1, 2014