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"Chairman: Professor H. S. SICHEL Rapporteur: Miss M. I. WATSONPapers:Unrolling of Copperbelt orebodies by J. H. E. Perry and V. H. WiikAn exploration model for tabular orebodies by G. S. Koch and R. F. LinkHarmonic analysis of copper and gold occurrences in the Arbitibi area of the Canadian Shield by F. P. Agterberg and A. G. FabbriMathematical models of orebodies by M. J. Newton and A. G. Royle Estimation of lateritic-type orebodies by A. JournelIn his presentation Mr Wiik said that unrolling could be regarded as a reversal of the natural process of folding, so that the aim of an unrolling procedure would be the reconstruction of original pre-tectonic conditions. While simply formulated, this aim might not always be achieved. The geometrical relationship between points on the deformed surface and corresponding points on the original surface is process-dependent, and a true reconstruction could be achieved only if the deformation history were known in detail.In this computer unrolling procedure all these complexities were ignored. Referring to one particular marker horizon, Mr Wiik said that it was assumed in the procedure that this marker was deposited as a horizontal stratum and that it had subsequently been deformed by simple flexure-type folding.The procedure allowed the geologist to incorporate his knowledge and conception of the deposit through repeated re-contouring with dummy points. This 'manumatic' aspect of the procedure had proved invaluable, not only in resolving specific unrolling problems but also in making the system more acceptable to the geologists in general.Unrolling served towards removing what might be termed `tectonic noise' superimposed on the primary distribution patterns for regionalized variables such as metal content and orebody thickness. From this point of view, variograms derived on the basis of unrolled-plan co-ordinates should be more meaningful in terms of depositional environment than are variograms calculated from a normal map projection.Mr M. M. Oosterveld remarked that it appeared from the paper that there were problems in applying the unrolling technique to ore reserve calculation, and asked whether there were not other methods that might be used for that purpose.Mr Wiik replied that at present unrolling played only a minor role in practical ore reserve estimation within Roan Consolidated Mines, Limited. The techniques currently in use differed from one orebody to another, but in general they involved projection onto a vertical longitudinal section or a horizontal plan, with subsequent grid interpolation by means of a standard computer contouring package."

Jan 1, 2014

By Lene Hansen

Sulphuric acid plants now and then see unexpected increases in SO2 emissions. Our experience is that it is not always easy for the acid plants to pin point the exact reason for the SO2 increase. Sometimes a catalyst bed is sacrificed even though reliable emperature readings and gas analyses could have verified satisfactory activity, hence the leaking heat exchanger is never discovered and after the shutdown the SO2 emissions are still too high. This paper will look into some basic catalyst management tools: Good record keeping is a necessity for collection of representative catalyst samples, reliable operating data is an inevitable starting point for all analysis and trending of operating data is a must for plant optimisation and troubleshooting. In addition these catalyst management tools will give a continuous updated knowledge of the catalyst status in each bed providing the basis for a more effective replacement strategy. The most typical reasons for increasing SO2 emissions will be presented together with easy guidelines for cross-checking of operating data, temperature optimisation and good record keeping.

Jan 1, 2009

By Lene Hansen

Sulphuric acid plants now and then see unexpected increases in SO2 emissions. Our experience is that it is not always easy for the acid plants to pin point the exact reason for the SO2 increase. Sometimes a catalyst bed is sacrificed even though reliable emperature readings and gas analyses could have verified satisfactory activity, hence the leaking heat exchanger is never discovered and after the shutdown the SO2 emissions are still too high. This paper will look into some basic catalyst management tools: Good record keeping is a necessity for collection of representative catalyst samples, reliable operating data is an inevitable starting point for all analysis and trending of operating data is a must for plant optimisation and troubleshooting. In addition these catalyst management tools will give a continuous updated knowledge of the catalyst status in each bed providing the basis for a more effective replacement strategy. The most typical reasons for increasing SO2 emissions will be presented together with easy guidelines for cross-checking of operating data, temperature optimisation and good record keeping.

Jan 1, 2009

By G. T. C. Emere, E. C. Hunter

The use of cylindro-conical settlers for the clarification of underground water by E. C. HUNTER- (Associate) G. T. C. EMERE-, B.A. (Hons.) (Keele) (Visitor) This paper analyses the performance of conical settlers on Harmony Gold Mine from 1959 to the present time, and describes the investigation that was undertaken to substantiate and improve the use of conical settlers for a new pump chamber in another part of the mine.

Jan 5, 1977

By S. Annavarapu

"Fragment size distributions play an important part in the design and planning of block cave mining operations. Though several methods have been proposed for estimating fragment size distributions in advance of mining, the calibration of these estimating procedures to field measurements has been a challenge. The Block Size Estimator (BSE) program was developed for providing an assessment of primary fragmentation expected in a block cave mine using drill-core piece length data and joint characteristics from the exploration and geotechnical evaluation programmes. In order to validate the results from the BSE program, the drill-core piece length data and the joint characteristics in different rock types from the DOZ block cave mine in Indonesia were used to help generate fragment size distributions in different areas of the mine. The predicted fragment size distributions were compared with the fragmentation observed at the drawpoints during operation of the mine.This paper presents the details of the validation of the fragment size estimates by the BSE program using fragment size distribution data from the drawpoints at the extraction level at the DOZ block cave mine, and the challenges encountered in developing reasonable correlations between the estimated and measured fragment size distributions. IntroductionThe assessment of fragmentation is an important aspect of the design and planning of the block cave mining method, and forms an integral part of the design of the excavations at the extraction level and the selection of material handling systems for transporting the ore to the processing stations. Secondary blasting requirements can also be estimated based on the fragment size distributions developed for the block cave (Laubscher, 1994).Several methods of estimating fragment size distributions in block cave mines have been developed based on joint set parameters estimated from structural data from oriented core drilling campaigns and mapping of available excavations and outcrops. The BCF program (Esterhuizen, 1999) estimates the fragmentation using a combination of empirical, analytical, and rational methods to model the behaviour of materials during the primary and secondary fragmentation processes. The program JKFrag uses advanced tessellation of joint traces to create rock blocks and then generate fragment size distributions (Brown, 2002). Nickson, Coulson and Hussey (2000) presented the details of processing of the geotechnical data from the Mont Porphyre project, including an assessment of block sizes from the data collected on the core logging sheet. The distance between natural fractures was used to create distributions of block lengths, and a distribution of potential block sizes was estimated assuming that the blocks had equal dimensions in all directions. The results agreed closely with the results of the BCF program. Hadjigeorgiou, Grennon, and Nickson (2002) demonstrated the use of oriented borehole data to provide characteristic block size distributions for a mining project using a software package called Stereoblock, which generates a three-dimensional joint network for a given volume and calculates the volumes of blocks created by the intersections of these joints, simulated as circular planes. The distributions of joint orientation and joint spacing generated from statistical analysis of the oriented core data are used for the creation of the Stereoblock model. The diameter of the circular planes representing the joints is determined based on the mean and standard deviation of the joint trace length obtained from scan-line mapping."

May 1, 2019

Mixtures of MnO and graphite were reacted under argon at temperatures ranging from 1200 to 1425°C, and the loss in mass of the mixture was recorded continuously. The results showed that the rate of reduction of MnO increased as the temperature increased and the ratio of MnO to C decreased. The effect of the particle size of MnO and of graphite on the rate of reduction at I350°C was very small in the range 63 to 250 µm for MnO and 45 to 355 µm for graphite. The rate of reduction at I350°C was increased markedly by the addition of Na2CO2 and K2CO3, was slightly increased by the addition of Fe2O3, was unaffected by the addition of CaO, MgO, and AI2O., and was decreased by the addition of SiO2. Some CO2 was always present in the effluent gas, and this was taken as evidence that the reduction of MnO occurred by way of CO2 as an intermediate product. The activation energy of the ratecontrolling step was 57,5 kcal, and this was similar to the measured activation energy for the gasification of graphite by CO., namely, 61,S kcal per mole of graphite. A simple kinetic model was derived on the assumption that the gasification of graphite was the ratecontrolling step, and the results over the temperature range 1200 to I425°C, when plotted in the appropriate form, yielded straight lines as predicted by the model.

Jan 1, 1980

By G. Akdogan, S. M. Bradshaw, A. P. Van Wyk, T. Punt

Recycling has become an important part of the lithium-ion battery (LIB) life cycle due to the growing demand for energy storage in applications like electric vehicles and renewable energy. Recycling spent LIBs provides a secondary source for strategically scarce metals, like lithium and cobalt, helping to reduce the environmental impact of LIBs. Organic acids have been proven to be effective lixiviants with the benefit of reduced environmental impacts, amongst which citric acid has shown to exhibit similar extraction performance when compared to mineral acids. Leaching LCO and NMC batteries with 1.5M citric acid and 2 vol.% H2O2 at 95°C, 20 g/L for 20 minutes achieved 93% Al, 90% Co, 96% Li, 94% Mn and 94% Ni dissolution. The strong chelating property of citric acid affects the separation of the metals, providing unique extraction opportunities. The first extraction uses 12 vol.% D2EHPA at a pH of 2.5 and O/A ratio of 2 to separate 96.4% Mn and 100% Al from the PLS in two counter-current stages. Stripping the loaded organic with 1.25M citric acid at an A/O ratio of 3 allows for up to 91% stripping of the manganese in a single stage. The second extraction then separates 96.5% Li from the PLS in three counter-current stages using 20 vol.% D2EHPA at a pH 5.5 and O/A ratio of 5. The raffinate remaining after the second separation contains 48.4 wt.% Co and 50.3 wt.% Ni. Keywords: Hydrometallurgy, lithium-ion batteries, metal recycling, citric acid, solvent extraction

Jan 1, 2020

One of the largest and most exciting cast murals in the world has been erected in Johannesburg, forming the focal point of the large atrium in the new headquarters complex for Johannesburg Consolidated Investment Company Limited (JCI). Known as 'Rockface', this is waterwal1 structure formed of cast stainless-steel panels

Jan 1, 1986

By D. W. Dean, J. A. Ryder

"A computer system designed to assist in maintenance scheduling and costing, and in monitoring the performance of equipment, is described. The emphasis is on the information retrieval and implementation aspects of the system.INTRODUCTIONThe cost of the maintenance of equipment can account for a substantial proportion of the total costs of any large industry. These costs are made up of the following elements:(i) capital expenditure,(ii) maintenance labour,(iii) maintenance spares,(iv) maintenance overheads,(v) production losses.Control of these cost elements cannot be achieved without a system which maintains and retrieves the necessary infor¬mation efficiently.The system should provide engineering management with the information necessary to:(i) establish the cost of maintaining items of equipment,(ii)establish the economic life of equipment,(iii) determine breakdown patterns for the establishment of optimum inspection, service and overhaul frequencies,(iv) establish work schedules for those responsible for the maintenance of equipment,(v) establish the optimum maintenance labour complement,(vi) establish the optimum stockholding of maintenance stores items,(vii) improve the performance of equipment,(viii) justify the selection of a particular type and make of equipment,(ix) establish the reasons for any abnormal usage of materials and labour, and to(x)reduce the dependence on the human element for the control of equipment maintenance activities.Many industries have comprehensive and numerous equipment maintenance records but they experience great difficulty in retrieving the required information in the time available and with the labour available. Many industries do not bother to maintain meaningful records, because of this difficulty."

Jan 1, 2014

By M. J. Sapko

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) recently conducted full-scale explosion experiments; these experiments evaluated the strength characteristics of various seal designs used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests were conducted within the multiple entry section of PRL's Lake Lynn Experimental Mine (LLEM) employing the only currently accepted test method endorsed by the Mine Safety and Health Administration (MSHA) for seal design in American mines. These explosion tests are labor-intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. Therefore, the PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept, that can facilitate the in-situ testing of seals in an operating mine. Two chambers within LLEM and one within the Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from tests in these chambers compare favorably with those from the large-scale explosion tests in the multiple entries. Preliminary size-scaling relationships for predicting the strength of standard seal designs as a function of entry size is also presented. In addition to testing seal designs at the required 20 psi static pressure level, the new facilities also allow for the determination of the seal's ultimate failure pressure. This new approach shows promise as an alternative evaluation method for improving mine sealing technologies which, in turn, will enhance the safety of the underground personnel.

Jan 1, 2003

By C. J. Lenz

The results of prospecting operations involving geological data and a large number of geochemical determinations of the metal content of soil samples are plotted and evaluated by computer. Anomalous areas are identified in each type of environment by selecting probability or population boundary values from frequency distributions. The anomalies are plotted to permit correlation with geographical or geological features. Ranking of prospecting targets is made using geographic pattern, geology, absolute value and metal ratios. Three short case histories are presented.

Jan 1, 2014

By T. Marsden

The demand for continuous improvement in the industrial world is an ongoing process. Some sectors, where the competitive forces are well established, have led the development of new and reliable technological innovations. Although the metallurgical industry can rightfully be proud of its process improvements, there is still work to be done in materials and in material handling. In some cases, the improvements will be as simple as adopting technologies that have been perfected in other processing or manufacturing industries. This paper discusses the next design generation for copper tankhouses which will yield: ?Improved copper quality ?Improved equipment availability ?Lower life cycle costs ?Safer operations. These benefits will be realized through new developments and design improvements in: ?Permanent cathodes ?Cathode washing ?Cathode stripping machines ?Anode preparation machines ?Improved lead anode design ?Recycling of lead anodes and refurbishment of cathodes. The demand for base metals, and in particular copper, has led to more research into improving efficiencies in electrowinning and refinery plants around the world. One of the areas previously taken as a matter of course was the production of lead anodes and stainless steel cathodes. In South America alone there are over 600 000 cathodes and anodes in circulation?a very significant figure.

Jan 1, 2009

By L. Ozdemir, B. Asbury, T. G. Rozgonyi

A new type of bit, that has been developed and is being evaluated, shows great potential in expanding the range of rock strength that can be cut by continuous miners and roadheaders. This new style of bit is called the frustum. The tools tested in this program were developed, manufactured and patented by Briese Industrial Technologies, Inc. The frustum derives its name from the unique geometric shape of the cutter, or cutting insert. The frustum shape cutting tool has previously been proven as an effective cutting tool for machining metals, metal matrix composites and polymers. The frustum rock bit has a very dense carbide frustum shape tip mounted on the end of a steel body similar to the conical bits typically used on continuous miners and roadheaders. In between the carbide frustum cutting tip and the steel body there can be a bearing that allows the frustum to rotate around the bit axis. When the bit is forced into the rock at a skewed angle, the frustum tip rotates as it travels. This rotation greatly reduces the cutting forces acting on the bit when compared to the current state of the art conical drag bits. This cutting force reduction, derived from the frustum’s cutting action, allows for much harder and more abrasive rock to be cut without quickly wearing out the bit. Full scale laboratory cutting tests have been performed with the frustum bit in direct comparison to the current state of the art conical bits. Field trials of the frustum bit are currently being planned. Test procedures, results and findings are presented.

Sep 1, 2001

By J. H. Zietsman, S. Maharajh, J. Muller

In the chlorination process for TiO2 pigment production, blends of titania feedstocks such as ilmenite, synthetic rutile (SR), natural rutile, upgraded slag, and chloride-grade slag are reacted with coke and chlorine at a temperature of around 1000°C to form TiCl4, which is the main product, and other waste metal chlorides. TiCl4 is the main feed material for the TiO2 pigment-making process. Feeding different titania materials to the chlorinator affects the amounts of coke and chlorine required for the process, the amount of waste generated, waste disposal costs, the amount of TiCl4 produced, and bed build-up rates. These factors influence the value of the feedstock. Generally, a higher TiO2 feedstock is more valued since less waste is generated and less reagents are consumed. To quantify the impact of different feedstocks on the chlorinator, a techno-economic model was developed to describe the chlorination process and estimate process variables at steady state. This paper describes the development of the model and studies in which the model has been used to quantify the effects of using different feedstocks.

Jan 1, 2014

By Y. Makola, M. Kilumba, S. Mwaba, P. Ilunga, F. Banze, B. Nel, P. Kyoni, N. Mautsa, R. Nkomba, G. Ilu

Kamoto Copper Company is a copper cobalt mining company established in Lualaba Province of Democratic Republic of Congo under a Joint Venture between Glencore PLC and Gecamines (the state-owned mining company). Operations consist of underground and open pit mines, a concentrator producing sulfide concentrate and oxide ores milled slurry, and a hydrometallurgy plant producing copper cathode and cobalt hydroxides from concentrate and ores. The production capacity is 300 k/a of copper cathode and 35 kt/a of cobalt hydroxide. Since Q4 2020, the Luilu hydrometallurgy plant has experienced operational instabilities due to increase in proportion of dolomite in the ore mined and fed to the plant. This was diagnosed by the significant increase in calcium grade in ore and acid consumption, continuous foaming, and overflow of tanks with subsequent adverse impact on equipment availability due to corrosion caused by acidic spills, structure integrity, and safety concerns around the acidic slurry spills. Production was adversely impact due above equipment availability and often throughput restriction to mitigate the foaming and overflows. A high gangue-acid-consuming ore management programme was developed with the aim of mitigating these impacts. The programme included: (i) use of defoamer agent in leach to stop foaming and overflow, (ii) design of a mechanical solution to leach foaming and overflow, and (iii) froth flotation for copper and cobalt minerals separation from dolomite. Only option (i) is presented in this paper. Through laboratory testwork, pilot-plant testing, plant trial, and full plant implementation, Kamoto Copper successfully implemented a defoamer agent (Kemfoam X9980) dosing at leach, resulting in significant reduction in foaming and overflow of leach reactors and countercurrent decantation thickeners. The optimum defoamer dose rate obtained was 20 mg/L. Since then, the Luilu recovered its operational stability, the corrosion of critical equipment ceased, and availability improved as the acidic leach slurry spills ceased. The constraint on throughput due to leach foaming was addressed and the frequency of sliming events in the thickeners was significantly reduced as the foaming on the supernatant surface ceased, with subsequent significant reduction in interfacial crud in solvent extraction.

Jan 1, 2023

By B. W. Wallace

Permitted explosives in South Africa are those explosives approved by the relevant State authority for use in fiery coal mines. The main tests that an explosive must pass for this approval are the gallery tests derived from the Buxton (U.K.) classification. These tests are described briefly. In addition, the safety of permitted explosives is affected by their ability to deflagrate, and to produce a naked flame after blasting, rather than to detonate fully. Tests done on this phenomenon are discussed. A further potential hazard of explosives is after-blast fume. The testing and behaviour of several permitted explosives in this respect are covered, both in the laboratory and in the field. Performance testing of permitted explosives, specifically the double-pipe, underwater, and ballistic mortar tests, and their relationship to field use, are considered in some detail. The application of traditional and new tests to permitted explosives leads to guidelines for the safe and efficient formulation and use of these products.

Jan 1, 1986

By K. G. Lomberg

The density used to covert volume to tons is critical in determining the real in-situ tonnage of Mineral Resources. However, the methods used to determine density and the use of different technical terms are seen to be inconsistent throughout the industry. Probably the best discussion addressing the determination of density was presented by Lipton (2001). This paper does not try to replicate this excellent work, but rather to review current industry practice and present a comparison of the approach to density in public reporting. Some of the technical terms used in reporting and the common methods applied are also discussed.

Sep 1, 2021

By H. Cevizci

In this study, a newly developed plaster stemming method is studied and compared with the usual dry drill cuttings stemming method for surface blasting in mines and quarries. Drill cuttings are generally used in open pits and quarries as the most common stemming material since these are most readily available at blast sites. However, dry drill cuttings eject very easily from blastholes without offering much resistance to blast energy. The plaster stemming method has been found to be better than the drill cuttings stemming method due to increased confinement inside the hole and better utilization of blast explosive energy in the rock. The main advantage of the new stemming method is the reduction in the cost of blasting. In one series of blast tests, blasting costs per unit volume of rock were reduced to 16 per cent by increasing burden and spacing distances. Also, better fragmentation was obtained by using the plaster stemming method. Blast trials showed that plaster stemming produced finer material. In the same blast tests, +30 cm size fragments reduced to 5.4 per cent of the total, compared to 37.7 per cent in the conventional method of drill cuttings stemming. With this method of stemming, vibration and air shock values increased slightly due to more blast energy being available for rock breakage, but these increased values were small and under the permitted limit for blast damage criteria.

Jan 1, 2012

By Y. J. F. Haven, G. H. J. Kitson, D. G. Beadle

I have read this paper with considerable interest. By using an automatic instrument to assess the dust samples taken in South African collieries, the authors are ahead of the gold mining industry, which still uses the laborious method of microscopic assessment, with its limited accuracy, of the half-a-million dust samples taken each year. As the authors state, the result obtained from the photoelectric assessment of the samples is approximately proportional to the surface area of the respirable dust. However, modern theory is that, in assessing coal dust, it is the respirable mass which is important in determining the danger to health. Thus Table II of their paper is of considerable value in showing the relationship between the P.E.R. value and the mass concentration measurement. Unfortunately this table only gives the mean relationship. The important point is to know the scatter around this mean. If the scatter is small, then this mean value (for different operations) would have considerable value in converting from respirable surface area to respirable mass, but if the scatter is large, then such a conversion, using a fixed factor, will have little value. In the text the authors mention the range of values as being between 3 to 24, but without a statement on the number of samples used to determine this range and their distribution, this is a rather nebulous statement. I hope, in their reply, that the authors will give, in statistical terms, some statement on the overall correlation between these two parameters. I might add that at present a member of my staff is working on similar relationships for dust samples taken in gold mines. Another factor which may well be most important in determining the danger of dust levels in coal mines is the composition of the dust, specifically its quartz content. I understand that the authors have some information on this point, and to make their results of greater value in International comparisons of dust levels and the concomitant development of pneumoconiosis, it will be extremely useful if they could place this information on record. Even though, as I have said above, modern theory postulates that respirable mass is a better parameter to use than respirable surface area, the problem remains of how to measure this parameter with short time sampling, which, as the authors point out, is their preferred strategy for dust sampling and dust control. I know of no easily portable instrument, independent of external power supplies, which can, in 5 to 10 minutes, collect sufficient dust to enable it to be weighed accurately. Thus the authors' implied intention of continuing to sample by their present techniques and using their present parameter to report the results is, in my opinion, an entirely valid decision.

Jan 10, 1968

By L. Tartibu, S. Assuli, P. Nkul, A. Kabimba, W. Elongo, N. Makhotla, D. F. Verwey, F. G. Ndiitwani, J. Bilali, T. Mukongo

The presence of colloidal silica negatively impacts various hydrometallurgy processes. This paper details the nature of colloidal silica, operational issues caused by colloidal silica, as well as various mitigation measures. MMG Kinsevere observed severe phase-continuity instability, increased crud formation, and reagent consumption, and reduced current efficiency in electrowinning with a deterioration in copper quality. Historical mitigation measures were initially implemented but failed to solve the problem. MMG Kinsevere successfully achieved efficient silica removal without adverse effect on the solvent extraction with the use of DEHSCOFIX® SC12 coagulant. A week into the coagulant trial, silica concentration had dropped from > 1500 mg/L to within 500 mg/L. The solventextraction plant recovered its stability and again operated at maximum capacity. Additionally, improvement was observed on current efficiency and copper cathodes quality with use of the coagulant.

Jan 1, 2023