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By L. 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 pinpoint the exact reason for the SO2 increase. Sometimes a catalyst bed is sacrificed even though reliable temperature 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 optimization and troubleshooting. In addition, these catalyst management tools will give 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 operating data, temperature optimization and good record keeping.

Jan 1, 2009

By R. G. B. Pickering

The hard rock gold and platinum mines in South Africa have seen little development in the technology of mining. Holes are still drilled in the rock?though the latest water hydraulic rockdrills will complete that task in two minutes compared with the eight hours for hand drilling. Charging up is with far safer explosives and with available initiation systems it is no longer necessary to run up the face lighting each fuse. Movement of rock in the stope is predominately by means of scraper buckets and scraper winches?these were first introduced in the 1920s. Support is still mainly rock, either in situ pillars or backfill, or alternatively wood. Just as the mining process has changed very little it is hardly surprising that the productivity of mining is also relatively unchanged. Major efforts have been made to mechanize the mining process. However, most of the narrow reef mines where ?trackless mechanized mining? was introduced in the early1980s have reverted to conventional mining. In the wider reefs mechanized mining is the option of choice, unfortunately most of the gold and platinum mines have very narrow reefs that are not suitable to ?off the shelf? equipment. The move to introduce room-and-pillar mining into the narrow UG2 reefs is at the expense of mining more waste with the reef, fortunately it appears that appropriate waste and reef separation processes are available. Room-and-pillar mining followed by long hole drilling and blasting of a narrow slot of reef out of the pillars currently appears to offer the best of both worlds?maximum reef recovery with minimum waste dilution.

Jan 1, 2002

By E. Spicer

X-Ray diffraction (XRD) provides useful information about the composition of an ore sample in terms of quantification of crystalline phases and amorphous content. The use of new, fast detection systems in XRD creates the opportunity to use this technique in modern process control. In the analysis of heavy mineral sands, XRD can identify the main mineral phases, such as ilmenite FeTiO3, rutile TiO2, Zircon ZrSiO4and quartz SiO2, and any other minor components present, such as anatase TiO2, magnetite Fe3O4, haematite Fe2O3or monazite (Ce, REE)PO4. Quantitative analysis is possible by various classical methods such as straight line or polynomial calibration with standards, but modern quantification analysis techniques such as Rietveld analysis (Bish and Howard, 1988) are attractive alternatives, as they do not require any standards or monitors. These methods offer impressive accuracy and speed of analysis. The Rietveld method compares calculated versus experimentally derived X-ray powder diffraction patterns for the sum of all crystalline phases. Another analysis technique offering great benefit to mining industries is cluster analysis. Enormous amounts of XRD measurement data are generated during the process control and material evaluation. New ways of handling such vast amounts of data are required to produce meaningful information for the end users. Cluster analysis greatly simplifies the analysis of a large amount of data from different processes or different raw materials, and automatically sorts closely related scans of an experiment into clusters and marks the most representative scan of each cluster as well as outlying patterns. The use of cluster analysis to evaluate the XRD data allows fast and reliable tracking of the process. It is the most economical procedure to have automatic data evaluation without involving any dedicated personnel in the process. Details of the techniques used, sample optimization methodologies, results, data precision and limitations will be discussed. The approach has potential as a relatively inexpensive, reliable tool, useful in the characterization of heavy minerals sand materials.

Jan 1, 2007

By M. H. M. von Wielligh

"Brick manufacturers supply a variety of uniquely coloured facebricks to the building industry, which requires a high level of colour consistency in the products. Colour variation in bricks is influenced by the composition and consistency of the white clay raw material. By blending varieties of naturally occurring white clay the manufacturers produce a unique range of facebrick products. Homogeneity of the white clay raw materials mined at Lenasia is crucial for producing bricks of consistent colour. Geostatistical investigations of the major element distributions (SiO2, Al2O3, Fe2O3, and K2O) and loss on ignition (LoI) were conducted. An analysis of the spatial continuity of these variables followed by ordinary kriging indicated that the upper white clay layer at Lenasia is richer in K2O and Fe2O3 than the lower layer. Consistency in the colour of facebricks depends critically on careful management of the variability in the K2O and Fe2O3 content of the clays. The geostatistical approach to understanding the distribution of elements in the clay allows miners to construct clay stockpiles of consistent quality for feeding the brick-making process. Geostatistical investigation of the chemical contents in other clay domains within the deposit is recommended, and could be extended to all facebrick manufacturers to assist in improving the colour consistency of their products. IntroductionMost clay in South Africa is used in the manufacturing of tiles, pipes, bricks, whiteware, refractories, and pottery. Bricks are manufactured from a wide variety of clay types, the behaviour of which during firing depends critically on the the clay mineralogy and chemical composition, but this relationship not well understood (Stein, 1982). The variety among clay deposits is related to the different processes of formation (Deer, Howie, and Zussman, 1992). The geochemical composition of the clay can vary between layers and within the same layer in an individual deposit (Lurie, 1984). The properties of clay minerals are determined by their structures and the different combinations of silicate layers, cations, and hydroxyl ions (Kingery, Bowen, and Uhlmann, 1976). South African clays can be classified as either kaolinite or montmorillonite and are seldom found in a pure form (Lurie, 1984). Different clay minerals affect the drying, forming, firing behaviour, colour, and quality of the brick product in different ways. Laboratory tests (full physical analysis) can indicate the suitability of a clay for the manufacture of ceramic products. The minerals most essential for the manufacturing of clay brick products are kaolinite, illite, and quartz (Stein, 1982)."

Jan 1, 2017

By A. Ahmed, A. Fathy, M. Eissa, K. El-Fawakhry, A. El-Mohammady

Silicomanganese is widely used as a complex reducer and an alloying addition in the production of various grades of steel due to its economic and metallurgical advantages. It is also used as a semi-product in the manufacture of medium- and low-carbon ferromanganese and metallic manganese. Manganese-rich slag, resulting from high carbon ferromanganese production, has the advantages of high manganese content, high Mn/Fe ratio, low excess oxygen, low phosphorus content, low fine content and low cost. Such slag seems to be very attractive to use as raw materials for the production of silicomanganese alloys. In the present study, experimental heats were designed and carried out to optimise the factors affecting the production process of silicomanganese using manganese rich slag in the charge. The results of pilot plant experimental heats showed that the optimum metallic yield and recoveries of manganese and silicon are obtained with initial slag basicity,(CaO + MgO) / (Al2O3), equals 1.8 by using dolomite as fluxing material and charging quartzite and fluorspar in percentage of 25% and 4% of the blend, respectively. The results showed also that an amount of 30% of coke in excess of the stoichiometric amount should be added. These result are relative for the specific high Al2O3 ores used.

Jan 1, 2004

By E. van Steen, G. M. Leteba

Optimizing the catalytic performance of multimetallic nanoparticle (NP) catalysts demands a concrete understanding of their design, while preferentially deploying wet chemical synthesis procedures to precisely control surface structural properties. Here we report the influence of reductants such as hydrogen-rich tetrabutylammonium borohydride (TBAB) and carbon monoxide-rich molybdenum carbonyl (Mo(CO)6) on the shape and morphological evolution of Pt-based binary (PtNi and PtCo) and ternary (PtNiAu and PtCoAu) nanostructures derived from a homogeneous solution of aminebased surface active agents (surfactants) in a high boiling point solvent. We successfully synthesized nanostructures exhibiting well-defined and composition-controlled surfaces deploying a one-pot synthetic approach. The development of the surface properties was, however, observed to be alloyspecific. The resultant highly monodisperse alloy NP with narrow size distributions and facet-oriented surfaces are expected to display enhanced functionality as catalysts for utilization in specific chemical reactions.

Jun 1, 2021

By J. Petersen, S. W. Robertson

Heap leaching is used extensively for the processing of low-grade copper, gold, and uranium ores. The hydrodynamics is often the most important factor that limits the rate of metal recovery. Over the past decades the author has performed physical and hydraulic testing of a large number of ore samples considered for heap leaching. The data were reviewed to investigate the effect of physical properties such as particle size distribution (PSD) and bulk density on the hydrology. The unsaturated flow through the bed is traditionally modelled with soil science models such as Brooks-Corey (BC) and Van Genuchten-Mualem (VGM), which relate the hydraulic conductivity to the degree of saturation, also known as the hydraulic conductivity function (HCF). However, most authors found a disconnect between the saturated hydraulic conductivity (KS) and the rest of the HCF, which is explained as resulting from a transition from capillary-to gravity-controlled flow. However, the author found no such transition, and found the flow to be governed by capillary flow throughout. Traditional BC or VGM fits were found to be appropriate, however it was necessary to modify the model to include a point of inflection, above which the hydraulic conductivity remains constant while the moisture content keeps on increasing. It was proposed that this is the result of unconnected or poorly connected pores, which fill with solution but do not create additional flow channels. The point of discontinuity was also found to correspond with the air entry point, measured independently from the air conductivity curves. On average, the air entry point corresponds to the experiential rule that the void saturation should remain below 65% for aerated heaps.

Dec 11, 2024

By I. Y. Motovilov, S. A. Telkov, M. B. Barmenshinova, Z. S. Abisheva

As a rule, removing waste rock at the beginning of the process improves the conditions for the flotation of minerals, and also reduces the operating costs of crushing, grinding and flotation. Lead-zinc ores in the Shalkiya deposit of the Republic of Kazakhstan are classified as difficult for enrichment, but taking into account their significant reserves, they are one of the main potential ores for the production of lead and zinc. Under industrial conditions, for processing ores of the Shalkiya deposit, a selective flotation concentration scheme with the production of lead and zinc concentrates is recommended. However, according to the recommended scheme, it is not possible to obtain high-quality concentrates of lead and zinc, with high metal recovery. The paper presents the results of studies of preliminary gravitational enrichment of lead-zinc ore in the Shalkiya deposit. Based on the fractional analysis for the particle size range of -40+8 mm, Henri- Reingard enrichment curves were constructed, separation density (2730 kg /m3) was established to isolate the light fraction with the lowest possible lead and zinc content, and gravity enrichment indices (0.7-0.71) were determined. It was found out that when using gravitational enrichment of the original large-sized ore in the Shalkiya deposit, tails are released at the beginning of the technological process with a yield of up to 20% with the extraction of silica up to 30%, calcite up to 11% and carbonaceous matter up to 12%. As a result of the studies, it was found that the beneficiation of crushed lump ore could be conducted in heavy suspensions. One of the positive aspects of the use of gravitational enrichment is the reduction of energy costs for grinding the heavy fraction, which was experimentally proved in this article. Keywords: Lead-zinc ores, Shalkiya deposit, fractional analysis, gravitational enrichment, floating fraction, sunken fraction, separation density

Jan 1, 2020

By A. R. Leach

Anomalous mining conditions can be described where the level of hazard is increased relative to normal conditions within a mining area. Normal conditions would be those defined as a Ground Control District in a mine’s code of practice, and for which mine standard support layouts are generally developed. It has been found that up to 80% of fall of ground accidents occur where anomalous mining conditions exists, typically in the vicinity of geological weaknesses. These areas require specific attention to ensure they are readily anticipated and identified and that appropriate strategies are used to reduce the hazards associated with them. As part of SIMRAC project GAP 607 checklists to aid identification and best practice mining methods were identified for a range of geotechnically anomalous conditions.

Jan 1, 2003

By J. R. G. Williamson

The Mining Division of Iscor, an integrated minerals and metals company, has recently completed a feasibility study for the establishment of a new heavy minerals mine and smelter in the Richards Bay area of KwaZulu-Natal, South Africa. The mine will produce a heavy mineral concentrate containing ilmenite, zircon, rutile and leucoxene which will be beneficiated at a central processing complex close to Empangeni. The ilmenite will be smelted to produce high-grade titania slag and pig iron for export. The ancient dune containing the mineral deposit is located some distance inland of the coastal dunes, and the sands contain a high proportion of extremely fine material which must be extracted ahead of the gravity separation process. Of the 56 million tonnes to be mined annually over the ten-year life of the mine approximately 23,4%?a total of 13,1 million tonnes of minus 45 micron residue fines?will have to be disposed of in a containment facility. The origin of the fine material is from the weathering of amphibole minerals. The remaining coarse sands will be returned to the mined area to re-create the original dune configuration. A number of options for the disposal of the residue fines have been examined and specialised laboratory tests undertaken to determine the deposition behaviour of the fines. The final solution involved the use of a ?sub-aerial? technique for deposition of fine material in a disposal facility. The resulting arrangement will adequately meet technical and environmental criteria. Upon closure after 10 years of operation, the surface of the disposal facility will be returned to sugar cane cultivation The paper refers to the various options considered and describes the problems associated with competent disposal of the residue fines and the development details of the final disposal facility.

Jan 1, 1997

By M. Weir, J. R. Cutland, L A. J. Pronk van Hoogeveen

"A computer system for the design of open pits to mine stratiform orebodies has been developed for use at Nchanga Consolidated Copper Mines, Ltd. The particular requirements of such a system, for example, the accuracy of representation of geological detail and the ability to follow footwalls, arc described in this paper, together with the methods that have been adopted to satisfy them.A modified version of the Open Pit Design Program of Rio Tinto Zinc Consultants, Ltd. is incorporated in the system and the geological data are converted into a form usable by the computer by means of a pencil follower. Some of the uses which have been made of the system are described, with reference to the long- and medium-term planning of the Nchanga Open Pit, the major producing pit at Chingola Division."

Jan 1, 2014

By S. J. Baumgartner

The ferromanganese industry is under pressure to deal with the slag arising from the production of ferromanganese, which is discarded in landfills or slag heaps. This material poses an environmental and health risk to surrounding ecosystems and communities, and disposal costs are increasing. Ferromanganese slag contains an appreciable amount of residual manganese metal, which can be exploited. Previous work has shown that the slag can be leached fully, while rejecting the silica to a residue. The methods that were investigated to recover manganese from the leach solution included hydroxide precipitation to upgrade the leach solution followed by manganese carbonate precipitation to produce a pure manganese carbonate product or a manganese carbonate furnace feed material, which would be recycled to increase manganese recoveries in the production of ferromanganese. In addition, electrowinning of electrolytic manganese dioxide from the leach solution was studied. The methods were compared in terms of selectivity, costs, and product quality. Co-recovery of the leach residue, which is a potential cement additive, is discussed. Among the methods investigated to upgrade the pregnant leach solution, hydroxide precipitation utilizing ammonia to adjust the pH appears to be the most effective in removing major impurities such as iron, aluminium, and silica to less than 1 ppm. The manganese carbonate and impure manganese carbonate furnace feed products met quality specifications. However, although the production of these materials was technically viable, the large amounts of base reagent that were required to raise the pH, and the associated high operating costs, rendered the process uneconomic. An optimization study was therefore carried out with the primary objective to determine the ideal acid amount to be utilized in the waterstarved digestion stage, thereby decreasing acid and base consumption while optimizing the quality of the pregnant leach solution, and producing a leach residue that contained <1% Mn. The outcome was an economically viable process. Additional benefits included an increase in the manganese content of the impure manganese carbonate furnace feed material, and a substantial reduction in the dilution of the pregnant leach solution, thereby maintaining high manganese concentrations that rendered the solution viable for electrowinning of electrolytic manganese dioxide, the production of which yielded a current efficiency of 74%.

Jan 1, 2014

By C. Massola, E. E. M. N. de Guzmán, M. G. Bergermana

The abrasiveness of a mineral or rock is an extremely important topic in the mining industry and is generally measured by the Bond abrasion index (AI). However, to determine such an index by the Bond test requires 1,600 g of sample with particle sizes ranging from ½” to ¾”, which are not available in certain situations, such as ore prospecting, drilling, and geometallurgical studies. In order to investigate the abrasiveness of smaller-sized sample materials, a modified LCPC test was developed, which allows testing fine materials (i.e., 1.0 mm or smaller) to predict wear in ore processing circuits and anticipate possible failures resulting from changes in abrasive characteristics of the ore being processed. The results for 16 different materials indicated a good correlation with the AI and the modified LCPC, resulting in a reliable alternative for the AI. Keywords: Bond Abrasion Index (AI), LCPC, abrasiveness

Jan 1, 2020

By D. Moses, J. A. Onyango

Carbonatites are generally competent rock masses with rock mass rating class II rating 60–74. In spite of their competency, they tend to be affected by weak features like manganese-iron veins and/or in situ rock damage due to brecciation associated with carbonatite complexes. Rock slope failure in such hard rocks is complex since such structures within the rock mass form weak links that could potentially control slope instability. In this contribution, a numerical simulation using phase2 v 7.0 was carried out to investigate the influence of in situ rock damage on the stability of mine pit walls. The outcome reveals that, the existence of breccia in the competent rock mass has the capability to reduce the slope stability performance particularly at gentle dipping angles of emplacement in close range to the slope toe. However, as the emplacement position of breccia moves away from the pit wall, the stability performance increases at gentle dipping angle <50º. On the contrary, at the dipping angle of 50° the performance of slope reduced, and at steeper angles >50° the impact becomes negligible. Thus, from a series of analyses, mine design in brecciated rock masses, the ratio of 1:5 between the breccia distance from slope toe and pit depth should be implemented to counter its impact, and if the breccia is within or close to the pit limit, a deliberate effort must be made to mine it out.

Sep 1, 2025

This paper sets out to consider a specific type of corrosion protection system, which is referred to as a Duplex Coating system. The dictionary describes a duplex system as consisting of two elements or a “twofold” composition. The duplex system described in this presentation is such a two-part corrosion protection coating, viz, hot dip galvanizing as the firm base or primer, followed by a top paint system designed to combat severe corrosive environmental conditions encountered in nature. In principle, the duplex system is a cost effective and balanced, designed coating that is suited to the environmental conditions and service life requirements.

Jan 1, 2009

By D. D. Munro

Finsch Mine is a Kimberlite diamond mine located at Lime Acres in the Northern Cape of South Africa. The mine was founded in 1961 and started surface-mining in 1964. Underground production commenced in 1990 using a Modified Blast Hole Open Stoping method for the mining of Blocks 1,2 and 3. Block 4 is currently being mined as a Block Cave. The process of identifying and optimizing a mining method to mine the Block 5 ore body started in 1991 and in 2006 Inclined Caving was identified as being a technically feasible method. This report aims to document the process employed in developing this method by the Block 5 Pre-Feasibility Team as well as discussing the technical challenges encountered during this process.

Jan 1, 2010

By F. T. Cawood, M. N. M. Cudjoe

The ability to conduct real-time material tracking in mines has been a long-standing challenge. Technological innovations such as radio frequency identification technology (RFID) have over the years contributed to the effective tracking of material flow and reporting of metal content. This paper outlines the laboratory procedures and results from testing the suitability of microdot technology as a viable technique for real-time material tracking in mining. The paper clarifies the reasons for conducting the test and presents the material safety data sheet (MSDS) from a South African and Canadian perspective. Microdots from three aerosol systems were immersed in water, heated to 100°C, and crushed into coarse and fine material. These tests were used to ascertain if the technology could withstand mining conditions. A strength, weakness, opportunity, and threat (SWOT) analysis was used to evaluate and compare microdot technology with RFID. It was shown that microdot technology has some potential to track ore parcels because data integrity was retained after exposure to post-blast mining conditions. However, more improvement is required to digitally detect microdots before the technology can be implemented at scale in the mining industry.

Apr 2, 2022

By F. T. Cawood

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

Jan 1, 2001

By B. McFadzean, N. Patterson, M. Becker, S. Geldenhuys

The retreatment of secondary tailings for platinum group metals recovery presents a range of potential challenges, which vary depending on the nature of the original ore and the type of pretreatment it was subjected to. These challenges include the prevalence of ultrafine particles, which promote slimes coatings on valuable minerals, hinder bubble-particle attachment, increase pulp viscosity, and lead to higher gangue entrainment; surface oxidation of minerals, which alters their floatability; and the presence of deleterious gangue minerals and residual platinum group metal species that are inherently difficult to recover by flotation. This study compares the batch flotation performance across a range of tailings samples from the eastern and western limbs of the Bushveld Complex. A complementary mineralogical analysis was conducted to gain deeper insights into mineral behaviour. The paper evaluates these findings to identify the key factors contributing to poor platinum group metal performance.

Mar 6, 2026

By D. Chetty

Process mineralogy forms an integral part of geometallurgy, with ore body characterisation being but one piece of the puzzle in optimising value derived from ore. This value is not only financial, but importantly speaks to sustainability from environmental and social standpoints. The reactive approach of traditional process mineralogy is increasingly being replaced by predictive methods in the geometallurgical sphere, for which mineralogical information must be timeously acquired on judiciously selected sample sets to understand ore variability and its impact on orebody processing. Such processes are not only metallurgical, but must incorporate mining and waste management protocols. Dwindling resources like water and energy also demand innovative approaches for lowering consumption and/or promoting recycling along the value chain. Addressing such challenges relies on appropriate characterisation of ore behaviour under different process regimes. Coupled with this, emerging characterisation tools are increasingly applied to understand the mineralogy of unconventionallypresented and difficult-to-process ores to meet societal and technology demands. Such tools are often accompanied by the generation of large, computationally intensive datasets, for which data management and storage are key requirements, particularly when deciphering temporal trends in ore and process variability. This paper will elaborate on these themes with examples that highlight the importance of process mineralogy throughout the minerals value chain. Keywords: Process mineralogy, ore characterisation, geometallurgy

Jan 1, 2020