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By G. Coetzer

"Prior to operating a non-recovery coke pilot plant, it was critical to ascertain coal cake stability during the loading of a 1 m3 coal cake into the oven. Various compaction parameters were verified and established on a small laboratory-scale compaction machine to obtain a coal cake of acceptable stability. These parameters include cake density, cake surface moisture, transverse strength (force applied perpendicular to the original compacted coal cake layers), and applied force to the coal cake. This work determined the behavioural characteristics of the coal while being compacted either with a full-sized or a 1/3-sized compaction plate in a 9 kg capacity mould. Two different coals were evaluated, namely Waterberg semi-soft coking coal (sscc) and Oaky North hard coking coal.The target wet cake density of 1 100 kg/m3 (79% of 1 400 kg/m3 relative density) was achieved for Waterberg sscc, with a particle size d50 varying between 0.6 mm and 1 mm, utilizing the 1/3-sized compaction plate in the laboratory-scale set-up, with 11.6% surface moisture and 92.2 t/m2 commercial equivalent applied force. For Oaky North hard coking coal, a wet cake density of 1 189 kg/m3 (85% of 1 400 kg/m3 relative density) was achieved at a surface moisture content of 12.3% and at a lower applied force than that for Waterberg sscc, i.e. 78.5 t/m2.Coal cakes of acceptable strength, and therefore sufficient stability for further processing, were obtained for all materials evaluated during this study.Further studies should be conducted to determine the effect of zeta potential during the compaction of coals.IntroductionExxaro Resources has successfully installed and commissioned a world-class stamp-charging horizontal 1 t electrically-heated pilot-scale coke oven at its Metallurgy Services facility. Prior to operating the coke non-recovery pilot plant, it is essential to ascertain coal cake stability during the loading of a 1 m3 coal cake into the oven. The design of Exxaro’s pilot plant is such that the coal cake is pushed inside the oven by means of a pusher plate, rather than through a ‘spoon’ feed mechanism, such as is found in industrial horizontal coke ovens. The pusher plate loading mechanism dictates that the coal cake should possess high stability and inherent strength during loading into the oven, owing to frictional forces exerted by the oven floor. In order to obtain a coal cake of acceptable stability, various compaction parameters needed to be verified and established on a small laboratory-scale compaction machine."

Apr 1, 2019

By B. P. Watson, D. Hoffmann, D. P. Roberts

Potholes on the Merensky and UG2 reefs in the Bushveld Complex occur as near-circular to elliptical depressions or slumps on the reef horizon, normally presenting as severe disruptions which prevent economic extraction. Within the pothole, the reef and other strata may either be attenuated, absent, or highly deformed, this being the result of the overlying hangingwall strata having slumped down. The hypotheses for pothole formation involve several mechanisms, including downward erosion, upward fluid movement, or synmagmatic deformation. When potholes are exposed in mine workings, significant fracturing is often observed. This fracturing is particularly evident in anorthosite rock types. Stress measurements were conducted in a pothole on the Merensky Reef to determine if the fracturing was due to high stress conditions. The paper describes the measurement results and numerical modelling that was done to determine the influence of depth and mining on the stress condition at the site. The results show that high stresses do exist in at least some potholes, and that current formation theories do not adequately explain the measured stresses. In support of understanding the high local stress associated with the pothole, the study explored several rock engineering modelling processes to validate the conditions of the study site and enclosing excavations. A better understanding of the stress conditions in potholes with additional data could lead to more appropriate support design and avoidance of potential rockbursts in these structures.

Jan 1, 2021

By R. MacRosty, R. Pula, P. Gebski, W. Braun

"This paper provides a progress update on three tapblock monitoring technologies that Hatch has been developing with our clients for non-ferrous smelting furnaces.The Tapblock Diagnostic System (TDS) is an advanced on-line monitoring system that uses temperature data along with embedded thermal model results to evaluate the condition of a tapblock over its campaign life. Hatch recently installed a second Tapblock Diagnostic System, some details of which are provided in this paper.The Tap-hole Acoustic Monitoring (TAM) system is installed on water-cooled copper tapblocks and uses the noise from the tapping channel to provide a qualitative indication of wear and deterioration of the tapping channel refractory. In addition, TAM can be used to monitor drilling and lancing performance, and potentially could also be used in the future as a guide for automatic drilling and lancing systems (Sadri et al., 2008).The third technology is the use of fibre optic sensors to measure temperature on the hot face and in the tapping channel of a tapblock. Fibre optic technology allows installation of numerous sensors in key locations where they are very sensitive to tapblock condition and also provide more extensive spatial coverage than is possible with traditional instruments. This paper provides an update on our efforts to address issues with premature failure of the sensor cables due to corrosion, and also converting the vast amount of data from the sensor cable into information that can be used by furnace operators."

Jan 1, 2014

By H. Dudycz, A. Skoczylas, P. Stefaniak, P. Pyda

In the era of Industry 4.0, technologies such as Big Data (BD) and the Internet of Things (IoT) play a key role, especially for multi-site manufacturing companies. In such companies, the challenge is to collect and process massive amounts of data from industrial devices and extract key information from this data in real-time for ad hoc decision-making. The ability to analyse data from industrial devices translates directly into streamlined production processes, cost optimisation, prevention of unplanned events, and safety during operation. In this context, particular attention should be paid to Big Data Analytics (BDA), whose main source is the Industrial Internet of Things (IIoT). The purpose of this paper is to propose an IT system architecture incorporating BD and the IoT for a mining company. The paper presents results from a literature review focusing on available BD and the IoT solutions for industry (mining in particular) for the purposes of the acquisition, integration, and advanced analysis of data. The advantages and disadvantages of the different solutions were indicated and gaps in the accessibility to dedicated functionality are identified. Based on the analysis of a multi-site mining company, the main challenges faced by such companies planning to implement BD and IoT solutions are identified. Also, a proposal for an IT system architecture incorporating BD and IoT for a mining company is described in the paper. The contribution of the article consists of the identification of the challenges faced by mining companies planning to implement BD and the IoT solutions, and the proposal of an IT system architecture that allows BDA whose main source is the IIoT.

Sep 1, 2021

By M. B. C. Brandt

Richter magnitudes for seismic events were calibrated for use as a Local magnitude scale in the West Rand (WR), Far West Rand (FWR), and Klerksdorp–Orkney–Stilfontein–Hartebeesfontein (KOSH) gold mining areas. Richter magnitudes are currently calculated from seismograms recorded by local surface cluster networks using tabulated calibration values for Southern California, published in 1958. The Richter (1958) model is incorrect for distances of less than 30 km and should be applied only to crustal earthquakes in regions with similar attenuation properties to those of Southern California. When compared to the South African National Seismograph Network (SANSN), the cluster networks, on average, overestimate seismic event magnitudes by approximately 0.1 of a magnitude unit. A calibrated Local magnitude scale was derived by means of a multiple regression analysis between the Local magnitudes reported by the SANSN and the largest zero-to-peak trace amplitudes measured on the cluster network horizontal seismograms, after modelling the attenuation of the seismic waves as these progress from the epicentre to the station position. Magnitudes reported by individual stations for the same event show a significant scatter around the average magnitude owing to the near-surface amplifications of the seismic waves at the recordings sites. Average magnitude should be estimated using as many magnitudes of individual stations as possible to ensure an accurate estimate. Larger event magnitudes should be compared with those recorded by the SANSN.

Nov 1, 2021

By V. A. Myazin, M. V. Korneykova, A. V. Svetlov, V. G. Minenko, D. V. Makarov, A. L. Samusev

The paper discusses the treatment problem of mine (waste) water for enterprises of the Russian Arctic. The wide range of relevant pollutants, financial resources, the availability of land for the construction of a treatment plant, waste generated during the treatment process are some of the factors controlling current and future process design solutions. All mining operations have adopted water treatment and water quality monitoring solutions, however there is no single approach to the problem and each industry participant operates within the scope of its available resources. The range of existing and emerging methods is extensive — from using constructed wetlands for the deposition of mineral nitrogen compounds in settling ponds, reagent deposition and chemical coagulation in exhausted mine workings, and filtering dams on the surface to retrofitting existing mine drainage treatment plants with the adoption of the electrochemical coagulation process. Methods of wastewater treatment from heavy metals, oil products, and nitrogen compounds are demonstrated in the example of two industrial facilities in the Murmansk region. It was found that the use of electrochemical coagulation provides effective treatment of mine water from NO3, NO2, Ni, Fetotal and petroleum hydrocarbons (the degree of purification from 50.5-99.7%), the use of phytotreatment system provides wastewater treatment from ammonium ions and nitrite ions by 53-84%, nitrate ions - by 22%. Keywords: Industrial water treatment, treatment flowcharts, settling ponds, constructed wetlands, reagent sedimentation, chemical coagulation, electrochemical coagulation

Jan 1, 2020

By G. Bezuidenhout, N. C. Steenkamp

Buying centres are the first point of contact that determines whether ore will be considered as having sufficient provenance to be considered ethically sourced. The information that needs to be captured on the blockchain platform ranges from reports on in-loco inspections and audits of mining and purchase sites. This will guide passive and active monitoring of mining activities, trade-offs for identification systems, including biometrics for the registration of artisanal sellers, scrutiny on the selection of security measures and companies for buyer centres and stockpiling warehouses, evaluation of active and passive infrastructure security, and remote monitoring applications. Assistance with selection and training in geochemical testing instruments to determine the grade of ore material or concentrates and sorting, on-the-ground investigations, guidance on monitoring methods from stockpile and packing area along the transport route to the final destination are required.

Jan 1, 2023

By A. Modi, C. Li, R. Kabwit, W. Y. Xinchao, R. Joshi

The KIMIN copper project can treat 1.7 million dry t/a copper-cobalt ore. It has three mills in operation, two using conventional milling in water and the third in raffinate. We introduce the project process circuit and the capital and operating costs of using the raffinate process compared with conventional milling in water. There is a capital saving of approximately 11.5% for major equipment by removing the pre-leach thickener. In addition, it also achieves an annual operating cost saving of USD 2.1 million due to an increase in 49% of acidic raffinate recycled and reduction in lime consumption. The features of CITIC’s new duplex stainless-steel ball mill ,as the key equipment of the system, are also introduced

Jan 1, 2023

By A. Mainza, A. Mabentsela

A finite element model of a 5 m radius DC arc ilmenite furnace in idling mode was used to test the notion that the slag solidifies when it comes in to contact with colder pig iron, thus constituting the initial step in the formation of solid slag at the slag-pig iron interface. It was found that a slag that is 150°C hotter than the pig iron does not solidify at the interface. The 150°C temperature difference between the slag and pig iron is a result of solid slag at the slag-pig iron interface, not the other way around as suggested in the literature. Calculations show that the thickness of the frozen slag at the slag-pig iron interface is 1.7 cm for the furnace used. It is proposed that slag solidification begins with the slow co-current flow of molten slag and pig iron in the outer parts of the furnace. This provides enough time for molten slag to interact with molten pig iron without solidifying. As the reduction products form due to reduction of the slag by carbon in the pig iron, the slag solidifies. This approach negates the need for the slag to solidify by merely coming into contact with an inherently colder pig iron. Making use of a low thermal contact conductance between the slag and pig iron was found to be sufficient to numerically capture the presence of solid slag at the slag-pig iron interface and to preserve the 150C difference between the slag and pig iron phase.

Mar 30, 2023

By U. König, N. Norberg

Ore mineralogy defines the properties during processing and metal extraction. Fast and frequent monitoring of the mineral content and related process parameters brings value to the mining operation and material processing. Decreasing ore qualities and increasing prices for raw materials require a better control of processed ore and a more efficient use of energy. Traditionally quality control in mining industries has relied on time consuming wet chemistry or the analysis of the elemental composition. The mineralogy that defines the physical properties is often monitored infrequently, if at all. The use of highspeed detectors has turned X-ray diffraction (XRD) into an important tool for fast and accurate process control. XRD data and their interpretation make the difference in the identification of minerals, in describing their distribution in ore bodies and in their beneficiation during processing. The use of statistical techniques such as Partial Least-Squares Regression (PLSR) or Principal Component Analysis (PCA) on XRD raw data has been successfully trialled to determine raw materials and processed ores, in addition to well established methods for mineral identification and quantification. PLSR can be used to correlate process parameters directly from the XRD pattern without investigating the mineral content. Hidden information present in the XRD pattern but not determined with traditional methods can be used to improve the characterisation of the analysed materials. The practical use for the direct determination of process relevant parameters during exploration and ore beneficiation will be illustrated in several case studies from mining and ore processing. Keywords: Geometallurgy, mineral monitoring, X-ray diffraction, process efficiency

Jan 1, 2020

By M. Louarrat, G. Enaime, A. Yaacoubi, A. Baçaoui, J. Blin

"The purpose of this study is to prepare a new activated carbon from olive stones for use in gold recovery by carbon-in-leach (CIL) and carbon-inpulp (CIP). The preparation method chosen was physical activation using steam. The effect of four process parameters: the residence time for carbonization, the activation temperature, the residence time for activation, and steam flow, were studied by the mean of response surface method (RSM) in order to optimize the yield, iodine index, and attrition characteristics. These two last responses were used as primary indicators of gold recovery capacity and mechanical strength. The results obtained show that optimal activated carbon can be prepared under the following conditions: a carbonization time of 157 minutes, activation at 921°C for 53 minutes, and a water vapour flow of 0.18 mL/min. This optimum carbon has an iodine value greater than 1100 mg/g and an attrition index in the order of 0.74%. These values reflect the quality of the precursor (olive stones) as a raw material for the development of an effective new activated carbon for the gold mining industry. IntroductionActivated carbon is an effective adsorbent widely used in industry due to its high surface area, well-developed reproducible microporous structure, and high degree of surface reactivity and adsorption capacity. World consumption of activated carbon is steadily increasing. It is primarily used in industrial wastewater and gas treatment and also for silver and gold recovery from cyanide solutions (Syna and Valix, 2003; Soleimani and Kaghazchi, 2008; Buah and Williams, 2010; Eddy et al., 2011). However, activated carbon is expensive and it needs to be regenerated after each adsorption cycle. In order to decrease the cost of manufacturing activated carbon, low-cost forest and agricultural wastes are considered promising new materials. In recent years considerable research has been reported on activated carbon from agricultural wastes, such as olive stones (Yavu et al., 2010), acorn shells (Sahin and Saka, 2013), peanut shells (Wu, Guo, and Fu, 2013), grape seeds (Jimenez-Cordero, 2014), coconut shells (Yalcin and Arol, 2002; Gratuito, 2008), palm shells (Sumathi, 2009), cherry stones (Jaramilloa, Gomez-Serrano, and A´lvareza, 2009), macadamia nut shells (Eddy, 2011), apricot stones (Soleimani and Kaghazchi, 2008), and bagass (Syna and Valix, 2003)."

Mar 1, 2019

By F. Dutoy, M. B. Stella, C. F. Carrozza

Rare earth elements (REEs) are indispensable components in the manufacturing of high-tech devices, renewable energy technologies, and defence applications. As global demand for these elements continues to rise, there is a pressing need to optimize extraction processes for both efficiency and environmental sustainability. This study explores approaches to rare earth extraction using Ionquest® 801 and integrates a predictive modelling to enhance process understanding and optimization. We conducted a screening test varying pH process to evaluate the best extraction efficiency. Starting pregnant leach solution (PLS), solution was prepared in the lab with the following rare earth elements: La, Ce, Gd, Dy, and Υ, at 0.02 M for each element. The data obtained were used to develop empirical and mechanistic models to predict rare earth extraction yields and flowsheet. Further tests were performed by mixing specific concentrations of different extractant and/or phase modifier. Our experimental results demonstrated the effectiveness of the proposedextraction methods, highlighting improvements in both yield and selectivity. The developedmodels successfully captured the complex relationships between process parameters and extraction efficiency, providing valuable insights for process optimization.

Nov 6, 2024

By J. Zhang, A. J. S. Spearing, L. Ma

Ore deposits are becoming more complex to mine as a result of the exhaustion of surface and other easily mined deposits. There is also increasing socio-political pressure to design more environmentally sound, sustainable, and safe mining practices. Wang and Ma designed a mining method for coal, similar to a modified drift and fill using a continuous miner to take sequential cuts (rooms) that are subsequently backfilled. The authors have modified the concept to make it more autonomous, safer, and less costly using highwall coal mining techniques, modified and adapted for underground applications. The method is more flexible than longwall mining and the percentage extraction would seem to be in the same range. In addition because of the backfilling, surface subsidence would not be a major issue and could be more effectively managed.

Feb 2, 2021

By W. K. Ting, A. Hasan

Mine stope is typically backfilled with cemented paste backfill, which provides a regional underground stability and also a reduction of aboveground tailings accumulation. During backfilling, a phenomenon known as arching occurs and affects the stress distribution of the cemented paste backfill. The change in temperature due to uncontrolled heat transfer from the surrounding rock mass and/or generation from hydration process complicates the stress distribution development of cemented paste backfill. This paper presents results of the investigation on the effects of hydration to cemented paste backfill behaviour when backfilled into a narrow wall model using uncemented paste backfill as controlled sample. The parameters considered include backfill type (cemented paste backfill vs uncemented paste backfill), curing temperature (30°C–60°C), and stress evolution during pouring, consolidation, and curing stages. Results show that uncemented paste backfill re-establishes arching effects more readily, with lower peak stresses and greater stress relaxation than cemented paste backfill, of which its behaviour is significantly influenced by hydration under elevated temperatures. The main outcome of this work is that hydration critically controls the stress-temperature response of cemented paste backfill, and the balance between hydration-driven strength gain and stress relaxation can be leveraged to optimise backfill mix design for safer and more efficient stope filling.

Jan 30, 2026

By M. Kumral, Y. A. Sari

Underground mining operations tend to have higher operating costs than surface mines. When metal prices decrease, profitability is jeopardized due to the high costs. Therefore, mining management harnesses new practices that increase operational efficiency. One way to manage this challenge is to invest in new mine planning practices. Stope layout optimization as a part of underground mine planning aims to identify a portion of the orebody in the form of production volumes (stopes) to maximize profit under roadway and stope dimension constraints. In this paper we propose a novel approach based on identifying ore-rich areas of the deposit and prioritizing their extraction through an iterative heuristic clustering approach. The proposed approach is compared with and validated by an exact method through a small mining example. The heuristics produced nearly identical results in a very short time. Finally, a case study was carried out using a larger data-set. The cluster-based iterative approach generated nearoptimal stope layouts in a computationally effective manner.

Mar 1, 2021

By T. Bhambhani, E. Arinaitwe

Solvay has developed several novel reagent innovations to improve separations in sulfide ore flotation and address major industry challenges. These innovations include: a) carbon management strategies to reduce the deleterious impact of organic carbon on flotation circuits; b) new collectors for heavily tarnished or oxidized Cu-Au ores; and c) a functionalized depressant for minimizing penalty elements in metal concentrates. Owing to their unique chemistries, these innovations exhibit a wide spectrum of rather unique properties that are quite in contrast to the traditionally used reagents. The chemistry, attributes, application, and advantages of these innovations are discussed in this paper based on laboratory, pilot, and plant results and observations for various ores

Jan 1, 2023

By N. K. Singo, J. D. Kramers

The reprocessing of tailings resources to extract gold on an industrial scale has become common practice. While these projects are common in the Witwatersrand basin, similar low-technology processes are not operational in smaller goldfields. This study explores the possibility of reclaiming the tailings dump of the Louis Moore Mine in the Giyani Greenstone Belt, investigates potential hazards to communities in the vicinity, and identifies mitigation strategies. Auger samples were taken from the Louis Moore tailings at depths of up to 5 m. Aqua regia leach analyses show Au concentrations of up to 1 g/t. Inferred estimations based on ordinary kriging (OK) and inverse distance weighted (IDW) methods put the residual Au resource in the Louis Moore tailings dump at 0.20 t. Reworking the tailings is viable, although a potential environmental risk exists in the form of elevated arsenic concentrations. Further exploration is required to determine the mineralogical associations of Au and As. Tailings reworking would assist in raising funds for mine rehabilitation. The secondary tailings could potentially be repurposed, which would provide employment and facilitate community development, as well as deliver environmental benefits.

Jul 1, 2021

By F. Dong, F. Yang, J. Wang, Z. Wang, D. Mingxia

Antimony oxide ores are important antimony resources, but their recovery is still a problem. In this paper, the adsorption behaviour and mechanism of dodecamine and quaternary ammonium salt on the surface of cervantite and quartz were investigated. The flotation behaviour of cervantite and quartz using quaternary ammonium salts and dodecylamine as collectors was studied by single mineral flotation experiments. The adsorbed amount was measured and infrared spectroscopy was used to study the ability of several cationic collectors to float cervantite and quartz. The results show that quaternary ammonium salts can simultaneously float the cervantite and quartz. It is difficult to achieve separation of the two minerals using quaternary ammonium salts as collectors. At pH>10, dodecylamine can float quartz but not cervantite, which can achieve reverse flotation separation of the two minerals. The difference between the abilities of quaternary ammonium salts and dodecylamine to float cervantite and quartz lies in the different ionisation properties of the two reagents. Quaternary ammonium salt is a strong electrolyte that is completely ionised in the pulp and exists mainly in the form of quaternary ammonium ions. Dodecylamine is a weak electrolyte and predominantly forms molecules under alkaline conditions. Keywords: Cervantite, quartz, dodecylamine, quaternary ammonium salts, flotation

Jan 1, 2020

By Mark Dangerfield

[Power-Point Presentation]

Jan 1, 2005

By F. Dinter, S. A. C. Hockaday, Q. G. Reynolds

The thermal decomposition of carbonate minerals as pre-treatment before smelting reduces the energy requirement for smelting. It can also make the combustion of fossil fuels for heating unnecassary. Thermal decomposition may become important in reducing greenhouse gas emissions when producing ferromanganese alloys while simultaneously reducing electrical energy demand during smelting. A kinetic reaction rate model for the thermal decomposition of manganese ores is presented, based on published reaction rate kinetics for the decomposition of manganese oxides and calcium carbonate. The model was validated against thermogravimetric data for two carbonaceous manganese ore samples and one ferruginous manganese ore sample. The reaction rate model shows that carbonate minerals in the manganese ores are decomposed at temperatures above 900 °C while pyrolusite is decomposed at temperatures from 450 °C to 500 °C. Mn2O3 decomposes rapidly at 550 °C. Braunite decomposition at temperatures below 1000 °C was negligible. The presence of organic carbon in the samples led to further reduction of the samples during thermal treatment.

Aug 3, 2023