Search Documents

By M. Steyn

The coordination compound tetrakis(1,3-diphenyl-1,3-propanediona to)zirconium(IV), [Zr(DBM)4], (DBM = dibenzoyl methane/1,3- diphenyl-1,3-propanedionol) was synthesized and characterized by single-crystal X-ray diffraction. [Zr(DBM)4] crystallizes in the monoclinic space group P21/c (a = 24.769(4) Å, b = 10.216(5) Å, c = 19.314(4) Å, and = 101.541(5)°). The coordination geometry around the zirconium atom, formed by the eight O-donating atoms of the four -diketonates, is found to be a near-perfect square antiprism. Crystal packing is stabilized by C?H... interactions throughout the crystal lattice. This structure is a noteworthy example of the application of ambient condition synthesis of zirconium compounds in N,N'-dimethylformamide (DMF) as reaction and crystallization solvent, highlighting the possibilities of aerobic condition metal purification through chelation.

Jan 1, 2014

By G. Chisakuta, P. Bwando, G. Mitshabu

By the end of 2022, the south-eastern Copper Belt region of the Democratic Republic of Congo was host to more than 40 small, medium, and relatively large sized copper solvent extraction sites. To date, solvent extraction reagents supplied in this region have never exceeded 50% of ketoxime content. We generated laboratory extraction and strip isotherms and used these with the BASF IsocalcTM modelling software to assess the benefit of using higher ketoxime blends on the main metallurgical performance indicators such as copper recovery and net transfer. Pure ketoxime extractants combine a relatively low strip point and a decent loading capacity, which are most effective as the pH of the pregnant leach solution gets closer to 2.

Jan 1, 2023

By G. Akdogan, M. Tadie, A. Tapfuma

The Southern African region contains abundant gold tailing heaps that are an environmental concern due to dust pollution and chemical contamination of nearby water bodies. Nevertheless, these heaps contain gold with potential to be extracted for financial gain. In this study, the feasibility of extraction of gold from a Witwatersrand gold tailings using glycine was investigated using a two-level full factorial design. Effects of variables such as glycine concentration at levels of 0.5–1.5 M with a solid–liquid ratio of 50–200 g/L were investigated. Although the solid–liquid ratio used in this study was below the industrial norm, it provides a starting point for investigating the applicability of this technology. To enhance the gold extraction, potassium permanganate pretreatment and copper ion addition were adopted. The results revealed that 91.4% gold extraction was achieved after 24 h pre-treatment of the tailings using 2 g/L potassium permanganate followed by subsequent leaching using 1.5 M glycine at pH 12, with 50 g/L solid–liquid ratio and 2 g/L copper ions. Statistically, the solid–liquid ratio and potassium permanganate pre-treatment of the tailings were found to be significant at 95% confidence interval, whilst interactions of copper ions and glycine concentration were significant factors. The work demonstrates that potassium permanganate pre-treatment prior to glycine leaching of low-grade secondary gold resources, such as tailings, can be beneficial. Furthermore, the methodology developed in this work provides an opportunity for further investigation of the recovery of gold hosted in complex mineralogical matrices.

Apr 14, 2024

By X. Xiang, W. Xia, J. Yin

"TiCl4 slurry containing valuable metals is an unavoidable by-product of the titanium ore chlorination process. The recovery of these valuable metals, which include titanium, niobium, tantalum, and aluminum, is an urgent issue to tackle in the titanium industry. The results of this investigation show that the valuable metallic elements can be recovered from the slurry by evaporation in a sealed container and leaching with dilute hydrochloric acid. After evaporation at 200°C for 60 minutes, nearly 99% of the titanium was recovered in the form of TiCl4, which was formed by the reaction of the TiO2 in the slurry with AlCl3. After evaporation, metals like niobium, aluminum, and tantalum remained in the residue. By leaching with 2.1 mol/L HCl at a L/S ratio of 6:1 mL/g at 80°C for 60 minutes, the soluble metals, such as aluminum, iron, and copper were all removed from the residue, and the niobium and tantalum were further enriched in the leach residue. A concentrate containing 53.40 wt% Nb and 5.57 wt% Ta was obtained by washing the leach residue with dilute aqueous ammonia under stirring. A potential waste water purifying agent containing 263.75 g/L AlCl3 was produced by purifying the leaching solution with Al(OH)3 and modified polyacrylamide. IntrodutionTitanium tetrachloride (TiCl4) is an important intermediate in titanium metallurgy that is widely used in the production of titania and titanium sponge (Akhtar, Xiong, and Pratsinis, 1991). In conventional titanium metallurgical processes, high-titanium materials such as synthetic rutile and high-titanium slag are reacted with chlorine to produce TiCl4 in a fluidized-bed furnace. Accompanying elements, such as Al, Nb, and Fe also react with chlorine to form chlorides, which are mixed with gaseous TiCl4 (Anderson, 1917). In the condensation process, gaseous TiCl4 is refrigerated and high-boiling-point chlorides are precipitated in the liquid TiCl4 to form a slurry containing 50~60 wt% TiCl4 (Wang, Xiang, and Wang, 2012).Various methods have been proposed to recover TiCl4 from the slurry, including microwave heating and spray drying (Wang, Xiang, and Wang, 2012, Wang et al., 2010a). To date, the only way to recover the TiCl4 is to return the slurry to the fluidized-bed furnace. However, this causes fluctuations in the temperature in the furnace, resulting in incomplete reaction between titanium-rich materials and chlorine. Therefore, the slurry is often rinsed with water and neutralized by adding lime, which caused serious environmental pollution and wastes a valuable resource (Roy, Bhatt, and Rajagopal, 2003)."

May 1, 2019

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 J. de Korte, Z. Loubser

"SynopsisThe aim of a blending stockpile is to minimize the natural variation in properties of a material. Two simulation models were written, for coneshell and chevcon stacking, and used to investigate the influence of different stockpile parameters on blending efficiency. The coneshell model is used to show that blending efficiency is highly sensitive to stacked height, with lower output variances observed for higher capacities. Output variance in both models also decreased when the stacker movement increment was decreased. For chevcon stacking, increasing stacker speed significantly increases the blending efficiencies. Increasing the length of the blending tail also reduces output variation, but this parameter would need to be weighed against the accompanying decrease in buffer capacity.IntroductionEven in the most uniform deposit of materials in nature, material properties will vary. The degree of variation can be measured, and usually resembles a normal distribution. The aim of blending and homogenization operations is to minimize the standard deviation of this normal distribution (De Wet, 1994). In general, the reduction in variation will result in a more efficient and cost-effective downstream process. Cement plants need a precise blend of raw materials to ensure desired kiln performance; boilers used in power generation are optimized for fuels of a constant specification; and even though the separation density in a coal washing plant can be adjusted, a constant product quality cannot be produced from highly variable feed (Denny and Harper, 1962). The process efficiency, product quality, and environmental compliance depend on consistency of characteristics in the material fed (Kumral, 2005) Many industries involved in"

Jan 1, 2015

By C. W. P. Finn

INFACON is of special significance to people in South Africa who are interested in ferro-alloys, because it was in South Africa that the idea of regular international congresses on ferro-alloys was conceived and developed. INFACON 74, the first-ever such congress, was held in Johannesburg from 22nd to 26th April, 1974, being organized by the South African Institute of Mining and Metallurgy, the National Institute for Metallurgy, and the Ferro Alloy Producers' Association of South Africa. Design Awards The Design Institute is inviting entries for the 1981 Shell Design Awards. Any product that falls into the three categories shown below, and that was designed in South Africa and is in production, is eligible for an award. Since their inception in 1970, the Shell Design Awards

Jan 1, 1981

By T. Mapeta, S. M. Rupprecht

Discussions on reasonable prospects for eventual economic extraction (RPEEE) include the CRIRSCO 2019 reporting template, JORC 2012, SAMREC 2016, CIM 2019 Guideline, and Regulation SK-1300. These reporting codes all conform to the principles of reasonable prospects for eventual economic extraction. To demonstrate that all mineral resources align with the RPEEE principles, the Competent Person is responsible for endorsing the mineral resource estimate. Moreover, establishing mineral resources and RPEEE requires technical input from numerous technical specialists, such as mining and geotechnical engineers, metallurgical engineers, social and environmental specialists, financial and governmental practitioners, and more. The aim is to improve the transparency of the disclosure of mineral resources and guarantee the investor or potential investor that the reporting of mineral resources is based on reliable technical, economic, environmental, social, and other relevant factors. This paper discusses the important protocols and definitions in some international reporting codes for the purposes of developing a guide memoire that will assist the Competent Person to interpret, establish and apply RPEEE appropriately and easily.

Jun 27, 2025

By A. Çelik

Wheel loaders are widely used in many sectors due to their mobility, operational flexibility, and low costs. The literature is mainly focused on improving the hydraulic, mechanical, and electronic subsystems of these machines in terms of efficiency or developing strategies for controlling these systems. In this study, the effects of the loader operator and different working conditions on the loading performance were investigated. The study was carried out at the Can Lignite Enterprise (CLI), which is a major coal producer in Turkey. In the study, which lasted approximately four months, a total of 808 measurements were performed to investigate seven different scenarios. The effect of a single parameter on loading performance was investigated in the first six scenarios. The results showed that the biggest impact on loading performance was caused by the operator's experience with 63.4%. On the other hand, the worst and most ideal working conditions determined from the first six scenarios were tested in the seventh scenario. It was tested as a script. The test results showed that the loading performance was 285.5% more effective under the most ideal operating conditions compared to the worst operating conditions. In addition, in the study, the loading performances of five loaders with four different capacities were examined in terms of energy efficiency and it was determined that the Kawasaki 115 work machine, which has a higher model and lower engine operating hours, was more advantageous. In the study, various suggestions were developed in parallel with the research results. The most prominent and easiest to implement of these suggestions is related to the selection of the loader operator.

Nov 27, 2024

By L. J. Su, J. Y. Zhang, P. W. Gu, J. F. Xu

Surface tension of mold flux is a key factor affecting optimum casting conditions. A thermodynamic model was developed to determine the surface tension of mold flux containing fluoride based on the ion and molecule coexistence theory of slag structure and Butler’s equation. The relationship between composition and surface tension was investigated by this model. Results indicated that the calculated values showed good agreement with literature data, and the average error was 8.19%. The surface tension value of the CaO–Al2O3-based mold flux was larger than that of the CaO– SiO2-based mold flux. The surface tension in a multi-component system decreased with increasing contents of SiO2, CaF2, and Na2O, which are considered surface-active components. This trend was more significant in the CaO–Al2O3-based mold flux.

Dec 11, 2024

By J. Stacey

There are four components to this guideline 1. Guidance on the socio-economic aspects of closure policy 2. Socio-economic closure activities mapped against the mining project life-cycle (a ?check status? tool) 3. A process guide for mine closure planning and implementation 4. Tools in support of mine closure planning and implementation How to use this guideline The four components are part of a hierarchy with: ?Overarching policy as the starting point ?The mine life cycle model as a quick process check tool ?The process guide for detailed practical planning and implementation as practical guidance ?Supportive tools as resources to address specific planning and implementation steps.

Jan 1, 2010

By J. Du, V. Shukla, C. R. Kumar, U. Shivangi, D. P. Chakraborty

During the processing of iron ores, a large quantity of low-grade tailings containing abundant iron values in fine particle size range is produced. Due to the increasing demand in the high-grade ores for metallurgical operations and the stringent environmental conditions imposed on mining activity, it is essential to utilise the waste tailing pond slimes. Recovery of iron values from these tailing ponds not only enhances the life of the existing operating mines, but also enables achievement of a sustainable process. Iron ore tailing/slime (-150 μm) is produced after scrubbing and wet screening of a low-grade iron ore. Tailing beneficiation of iron ore has been addressed either by flotation or wet high intensity high gradient separation. The present paper aims to recover iron values from discarded slime containing assay ~56% Fe, ~6.5% SiO2, and ~7.0% Al2O3 from the Noamundi processing plant by using a high gradient magnetic separator (HGMS). In this process, tailings are effectively processed with a vertical pulsating high gradient magnetic separator to produce a relatively high-grade iron concentrate. The results of investigation indicate that this novel process is capable of producing an iron concentrate assaying ~ 60% Fe and ~3.25% alumina with a yield of ~55 % on weight basis and recover > 65 % iron bearing particles from the tailings. More importantly, the corresponding tailing contained ~45% Fe. It was concluded that this novel process may be effectively used to recover iron values from low-grade hematite tailings. Keywords: Iron ore slime, Fe recovery, HGMS, yield, Noamundi

Jan 1, 2020

By Q. G. Reynolds

The presence of dust and fume suspended in the freeboard region is a common feature of the operation of direct current (DC) plasma smelting furnaces. This occurs primarily as a result of the use of fine feed materials together with the open-arc, open-bath operation of such smelters, and is exacerbated by the high velocities and turbulent mixing of the gas in the vicinity of the arc jet. Dust and fume losses into the furnace off-gas system can be significant in some cases and may have economic, operational, and environmental impacts on the process. A computational modelling study is presented in which the concentration of dust material was considered as a continuous field subject to a governing partial differential equation. Settling behaviour was calculated as a function of particle size, local gas/plasma temperature, and other physical properties. Development of the coupling between the concentration field and a magneto-hydrodynamic description of the arc is shown, and the resulting models were used to compute various aspects of the behaviour of the concentration field in the arc region for a variety of furnace conditions. Time-averaged as well as transient models of the arc were used to generate the results presented. Qualitative case studies produced several practical suggestions for furnace operation, including increased dust capture by the bath when feed ports are located closer to the electrode, and the possible effects of feed segregation in the furnace freeboard based on dust particle size and density.

Jan 1, 2014

By P. Ramsaywok, S Ndanduleni, G. Legodi

The objective of this paper is to share the optimisation journey of a pilot Reflux classifier (RC) circuit in the Exxaro GG1 plant, at Grootegeluk beneficiation complex in Lephalale, South Africa. The RC circuit was commissioned in 2016 to produce semi-soft coking coal at its fines circuit; however the stability of operation as well as the quality control of the coal product was not fully achieved. Various test campaigns and optimisation studies were conducted to understand and optimise the RC circuit at GG1. The studies revealed circuit design inefficiencies; provided an improved technical understanding of the current pilot circuit and the parameters required for the circuit to reach a stable operation. The operation was stabilised with its current inefficiencies to produce an average 12.5% ash semi-soft coking coal product for sustained periods, above the initial target of 10.3% ash. Keywords: Reflux classifier, coal

Jan 1, 2020

By T. Bezuidenhout, J. D. Visagie

In recent years the requirements for a barrier system between the waste body of tailings storage facilities (TSFs) and the natural ground (NG) has necessitated the use of HDPE-lined TSFs in South Africa and other countries. The addition of an HDPE liner creates an interface between, inter alia, the tailings and surrounding soils on the footprint of the TSF. It is known that low-strength materials beneath slopes can cause slope instability. One method which can theoretically mitigate this instability of a lined TSF is the addition of stability bunds along the footprint of the TSF. Altering the profile of the footprint to include slope changes which oppose the direction of the failure creates passive slices in a limit equilibrium analysis. The passive slices actively oppose the movement of active slices, resisting the mobilization of tailings, thus greater active slice forces are required to develop a failure surface running along the liner interface. Two scenarios are presented and compared. The first scenario retains the ground profile unaltered and the second scenario includes stability bunds along the ground profile. An in-depth assessment is made of the interslice forces and the interface shear stresses for each scenario. The theoretical background is discussed in greater detail to determine the mechanisms of reinforcement provided by the bunds.

Jun 2, 2022

By J. E. Dickinson, R. Campbell, M. J. Cole, K. P. Galvin, M. C. Cole

It is common practice in the beneficiation of iron ore ultrafines to apply reverse flotation, and hence float the gangue minerals, leaving behind a high-grade iron ore product. Given the difficulty in floating particles finer than 20 μm, especially those finer than 10 μm, it is necessary to subject the feed to desliming ahead of flotation. There are two problems with this approach. Firstly, given the known inefficiencies of cyclones, desliming needs to be aggressively applied to particle sizes upwards of 45 μm to ensure all the offending ultrafine gangue is removed. Secondly, desliming also removes a significant portion of the valuable iron ore. Thus, a significant portion of the ultrafines, including the iron ore, is lost to the tailings. This paper examines the direct flotation of iron ore fines using the Reflux Flotation Cell. The RFC operates using a concentrated bubbly zone, in the absence of a conventional froth zone, for delivering strong counter current washing through an inverted fluidised bed of bubbles ahead of the product discharge. A system of parallel inclined channels in the lower part of the cell provides enhanced segregation of the bubbles from the tailings, preventing the loss of air bubbles into the tailings. Experiments conducted under semi-batch conditions produced encouraging results with concentrates of ~65% Fe grade in a single flotation stage. Comparatively, up to five successive batch flotation stages were required when using a laboratory scale batch mechanical flotation cell to achieve similar Fe grades. For a given grade, lower Fe recoveries were typically achieved by the RFC. This was attributed to the effective prevention of ultrafine particles succumbing to hydraulic entrainment under a positive bias flux, as well as an increasing feed volume involved in the semi-batch operation using inverted fluidisation water for cleaning. Overall, similar grade-recovery curves were produced, however, significantly higher grades were obtained by the RFC and with fewer separation stages. Keywords: Desliming flotation, iron ore, modified release analysis, reflux flotation cell

Jan 1, 2020

By B. J. Coetzee, P. W. Sonnendecker

The quality control of a two-stage coal washing process involves several complex components that need to be modelled accurately, to enable autonomous control of the process. The first objective is to develop a method to track the material through the washing process, while ensuring accurate washing prediction models are used. This was achieved through a digital twin model of the Grootegeluk 1 coal processing plant. The model is the amalgamation of manipulating and combining of data-sets from the plant historian, geological wash tables, and mining dispatch servers. This information is then used to control and set the processing medium densities of all 15 modules on the plant, 10 modules in the primary wash and 5 modules in the secondary wash. This controller has been successfully implemented and controlled the plant for 10 days.

Aug 2, 2022

By C. Birch, J. Perold

"Due to the challenging geological environment of the Postmasburg Manganese Field (PMF), a study was conducted to determine if any benefits would derive from the inclusion of resistivity data during threedimensional (3D) modelling of the manganese resource. This was achieved by estimating manganese resources from 2011/2012 drilling data and comparing them with manganese resources estimated from the same drilling data and resistivity data collected during 2013 and 2017.Both models were adjusted to limit their extent to the same 3D modelling space. Significant volume and tonnage differences were observed for all lithological units. The greatest differences were noted in the manganiferous zones of alteration – 7.200 Mt for the geological model versus 3.700 Mt for the geoelectric model.This study showed that the inclusion of resistivity data can reduce exploration costs significantly, as a direct consequence of the resistivity data allowing more accurate siting of boreholes. This decreases the number of boreholes, samples, and analyses required due to the 3D electrical delineation of mineralized areas prior to drilling.An additional benefit is the ability to more correctly forecast the net present value of an operation due to more accurate estimation of manganese resources and stripping ratios. This is clearly demonstrated by the estimated gross profit estimation of R409 million for the geological resource model versus R264 million for the geoelectric resource model.The addition of resistivity data can, therefore, reduce exploration costs and can increase confidence in geological and financial modelling. It would be reasonable to conclude that this approach could also be used for karsthosted massive sulphide deposits. IntroductionAccording to Corathers (2014) and Gajigo, Mutambatsere. and Adjei (2011), South Africa holds between 75–80% of global manganese reserves, followed by Ukraine (10%), Australia (3%), India (3%), and Gabon (2%). The known, land-based, manganese resources located elsewhere are estimated at 2%.The majority of economically important sedimentary manganese ore deposits in South Africa are situated in the Northern Cape Province (Gutzmer, 1996). Manganese ores of the Postmasburg Manganese Field (PMF) were discovered in 1922, and the Kalahari Manganese Field (KMF) in 1940. According to Astrup and Tsikos (1998) and Gutzmer (1996), mining of manganese ore from the PMF ceased during 1989 in favour of the superior quality of manganese ore from the KMF."

Mar 1, 2019

By G. Kleyn

"Sub-standard practices and their adverse impact on safety performance remain a challenge in the South African gold mining industry. The purpose of this study was to investigate the root causes of sub-standard practices and the effect on safety performance in South African gold mines. The focus of the study was on the underground production operations at a gold mine in the Free State. The study consisted of three parts: a personal investigation into the causes of sub-standard practices at the mine, a comparison with the results of a cultural study performed at the West Wits mines, and a behavioural survey.The studies described in this article yielded similar results in terms of the key drivers behind sub-standard practices. It was found that substandard practices had a number of causes, and the origin lies within the habits, attitude, and behaviour of employees. Current methods of addressing sub-standard practices and improving safety performance were found to discourage employees from performing work safely and according to procedure. It was concluded that the lack of critical behavioural habits for the given work environment and job title could possibly be the primary reason for the occurrence of sub-standard practices. IntroductionSince the implementation of the Mine Health and Safety Act, 1996 (Act 29 of 1996) and the Mine Health and Safety Regulations, the South African mining industry has been striving to improve health and safety performance and has placed great emphasis on adherence to mine standards.The Act requires employers in the mining industry to report accidents, incidents, and dangerous situations to the Regional Principal Inspector of Mines in their area. The data provided by employers is captured and analysed by the South African Mines Reportable Accident Statistical System (SAMRASS) and made available for public viewing (Department of Mineral Resources, 2011).A review of the national mine-related accident statistics shows clearly that the South African gold mining industry has improved its safety performance markedly over the past decade, but is still facing major challenges (Figure 1). These include meeting the Mine Health and Safety Milestones (Department of Mineral Resources, 2011)."

Jan 1, 2016

By John W. Harbaugh, Alfredo Prelate

The goal of the study described here is to develop objective. quantitative methods for estimating the outcome probabilities of exploratory oil wells. The study employs the 're-experience' approach, in which historical data are used in a manner which attempts to recreate the past. Our past experience, of course, is the principal guide to the future. To appraise present-day oil prospects, however, we must analyze prospects that have been drilled in terms of how these former prospects were interpreted before they were drilled. An analysis of how they are interpreted after they were drilled is an inadequate guide to the future because our hindsight knowledge is superior to our foresight knowledge. Objective calculation of future outcome probabilities, then, requires that we attempt to treat past information in a manner analogous to that in which we must treat present information in forecasting future outcomes.

Jan 1, 2014