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By M. Steyn

[Zr(C9H6NO)4]?(HCON(CH3)2)?(H2O), where (C9H6NO) = 8-hydroxy quinoline (oxH), was synthesized and characterized. This tetrakis-coordinated zirconium complex crystallized in the triclinic crystal system (Pi, Z=2) along with water and N,N?-dimethylformamide(DMF) solvate in the asymmetric unit. The metal atom is surrounded by four N,O-donating bidentate ox-ligands that are arranged around the metal centre to give a square antiprismatic coordination polyhedron with a small distortion towards a dodecahedral geometry. Crystal packing is stabilized by intermolecular interactions of adjacent oxine ring systems in neighbouring molecules, as well as hydrogen bonding of the aqua and DMF solvate molecules, linking the molecular entities into a supramolecular three-dimensional network.

Jan 1, 2013

By C. N. Harman, N. S. S. Rama Rao

Production of Ferro-alloys through submerged electric arc furnace involves use of electric power as one of the major inputs. Hence the production by this power intensive process can be made economically more competitive if the specific power requirement for smelting each ton of the product is brought down. This becomes all the more necessary where the power cost is comparatively high, like in India. Since the day FACOR started production of Ferro Chrome in 1968, briquetted chromite fines along with lumpy ores were used as feed. Subsequently the increase in the proportion of briquettes and reduction in lumpy ore helped in increasing the use of chromite fines and also brought down the specific power requirement. Meantime FACOR had been closely watching the technical development of use of sintered pellets in Outokumpu and SRC Processes which need still lower specific power. But the high capital requirement for a pelletisation plant kept FACOR from introducing pellets feed to their Ferro chrome furnaces. So this was postponed to be adopted in future. In February 2004 in the ?1st Ferro-Alloys India?, a paper [1] was presented by Dr. Amit Chatterjee. In the questions period after the presentation of the paper there came up a discussion in which it was revealed that with the Indian high grade chrome ores it was not possible to make sufficiently strong pellets, unless a larger percentage of bentonite is used as binder. This is because the Indian high grade Chrome ores have different mineralogy of gangue content compared to low grade ores in Finland and South Africa. Higher usage of bentonite gives rise to higher slag volume and this would result in increased specific power. Since FACOR had plans to go in future for sintered pellets feed, this gave rise to a doubt on success of pelletisation for Indian high-grade chrome ores. This prompted FACOR to take up experimental production of sintered chromite pellets and use of the same in one of their existing furnaces for production of high carbon Ferro chrome. The results are encouraging and are summarized in the paper.

Jan 1, 2007

By D. G. Krige

Using chip sample data and spatial structure parameters from a large mined-out section of a South African gold mine the advantages to be gained from a regular underground borehole drilling programme have been investigated for short- and medium- to long-term planning based on block valuations. The results have been compared with the current position, which relies invariably on the extrapolation of limited peripheral sampling data from raises, gullies or stope faces. Some preliminary work has also been done regarding the implications of such underground drilling on costs used for the present pay limit calculations. The results of the study, though preliminary, show that the net advantage of advance regular underground drilling could be substantial and that a more intensive follow-up research is warranted.

Jan 1, 2003

By F. Lombard

We consider the Grubbs estimation of the precision of an online gauge. Typically, this type of estimation involves independent results from two or more reference instruments (sampling and laboratory analysis operations). The properties of the estimator are then independent of the product variability. However, the use of more than one reference instrument entails significant additional costs. The two-instrument Grubbs estimator, which is based on results from a gauge and a single reference instrument, has the disadvantage that its standard error is heavily dependent on the degree of product variability. We propose a new estimator that has a variance that is more or less independent of product variability. In fact, the variance is typically less than that of the Grubbs estimator based on the use of two reference instruments. In order to function successfully, our methodology requires some prior knowledge of the extent of product variability and of gauge precision. In practice, such prior knowledge is often available and it is a weakness of the traditional two - and three-instrument Grubbs methods that no use is made of such knowledge. The efficacy and robustness of the new method is illustrated by Monte Carlo simulation.

Jan 1, 2012

By P. J. Hancox

Heavy mineral deposits have been known from Liberia since the1950s from both river and beach placers. The heavy mineral content of beach sands ranges between 28?62% and the suite includes ilmenite, rutile, zircon and magnetite. These occur together with kyanite, sillimanite, staurolite and garnet. The average ilmenite content is 82% with minor zircon (11%), rutile (6%) and monazite (1%). The ilmenite is, however, of poor quality with haematite intergrowths and a titanium content ranging from10?42.4% (average ±25% TiO2). The amounts of rutile and zircon, while of suitable quality, have also previously been deemed too low for economic exploitation.

Jan 1, 2000

Bateman Engineering managed the establishment of a second diamond treatment plant at the Letseng Mine in the Mokhotlong District of northern Lesotho, about 100 km from the town of Buthe Buthe. Letseng Diamonds Proprietary Limited, is owned 70 % by Gem Diamonds and 30 % by the Government of the Kingdom of Lesotho. The second plant, which commenced construction in late 2006, doubled Letseng Mines' hard rock processing capacity from 2.6 million t/yr to 5.2 million t/yr, making it the worlds' seventh largest diamond mine by throughput. Bateman Engineering provided the engineering design, procurement and construction management of the new plant.

Jan 1, 2010

By M. J. Leeuwner

Computational fluid dynamic (CFD) modelling is used to research the complex flow structures that exist in a hydrocyclone. By simulation of a two phase (water and air) flow system, the internal flow and multiphase interactions are investigated. The suitability of CFD modelling as a design tool is further evaluated by examining the effect of varying device dimensions. Three hydrocyclone geometries, used in previous studies, are specified. A transient simulation approach, which employs the Reynolds Stress Model as turbulence model and the Volume of Fluid model as multiphase model, is followed. Results are validated qualitatively against experimental measurements from the previous studies. Keywords: CFD modelling, hydrocyclone, Reynolds stress model, multiphase flow

Jan 1, 2008

By J. de Villiers

Through the application of the Rietveld method, X-ray diffraction analysis has developed into a fully quantitative method for phase analysis. The Rietveld method itself has progressed from an unstable method that required constant operator intervention to a stable and robust method suited even for routine analysis. The method, however, requires a good initial calibration and periodic checks on its precision and accuracy. Several examples from minerals processing, pyrometallurgy, and materials science show the strengths and applicability of the method. The limitations and sources of error are also discussed.

Jan 1, 2007

By W. J. Theron

The purpose of the paper is to give an introduction to the concept of fatigue and its causes in the mining industry. By knowing the fundamental role it plays, together with its dynamics, can positively contribute to a mine?s safety management system. The difference between physical and psychological fatigue will be addressed with a possible range of causes that could trigger fatigue. There are two main sources of fatigue: firstly, work-related fatigue which is associated with activities at the workplace; and secondly non-work-related fatigue. The shared responsibility between the employer and employee is also discussed as it involves factors that occur both in and outside the workplace. Employers have the responsibility to manage fatigue through using a risk management approach. Employees have the responsibility to ensure they get enough sleep, take sufficient and regular nutrition, are healthy and physically fit and come to work fresh and alert. The impact of the implementation of a fatigue management plan and procedures has the potential to eliminate employee fatigue or its causes, reduce the likelihood of fatigue occurring in the workplace, and counteract the effects of fatigue when it occurs. Factors considered when implementing a fatigue management system include: extended hours of work, shift work, time of day and work design. Fatigue is one of the major role players (either causal or contributory) when it comes to causes of fatalities in the mining industry. Our main challenge in identifying whether fatigue played a role is the fact that it cannot be tested in post-mortems like drug or alcohol abuse. It is an aspect worth understanding and getting an organization sensitive to managing it properly to benefit both organizational as well as employee needs. Keywords Signs of fatigue: Causes of fatigue, circadian rhythms, the fatigue equation, fatigue management, fatigue affecting safety, fatigue fighting tips, lifestyle suggestions.

Jan 1, 2011

By P. W. Lotz

Traditionally, bottle roll tests have been used to optimize the extraction process for best gold extraction and recovery. Such tests typically involve exposing the ore to defined reagent concentrations (lime, cyanide and sufficient oxygen) and balance the gold input with recoveries and losses. With mounting pressures to accommodate sustainability issues during development work, it became apparent that much more information would be required on the interactions and kinetic behaviour of solid and solution species during the entire leach process. This information is vital to enable proactive management of critical issues such as cyanide, arsenic, water and tailings management. Inadequate management of these aspects has led to temporary closures and, in cases of non-compliance, to the dynamically changing regulations. MINTEK?s advanced leach facility (ALF) is being developed with the aim of bridging the knowledge gap between the gold leach process and the predictable environmental impacts upon discharge. The facility aims to monitor all parameters of relevance such as pH, Eh, dissolved oxygen, metals, cyanide species, and viscosity during the entire process to enable more informed decisions on practical interventions. The presented set of data reflects first experiences gained from processing a refractory gold ore concentrate. Attempts at optimizing the process were limited due to the developmental nature of the work. Data relating to leaches with differing preoxidation conditions and cyanide staging is presented.

Jan 1, 2009

By E. H. Myrhaug, K. Aasly, T. Malvik

Six different types of quartz and quartzites used as raw materials by ferroalloy plants have been investigated with respect to their thermo mechanical properties. In order to investigate the effect of the thermal shock caused by the rapid heating of quartz when it enters the furnace, the following techniques have been used for both in situ investigations and investigations of pre-heated quartz: -Heating stage microscopy for in situ observation of heating effects. -Shock heating of quartz in an induction furnace An optical microscope-mounted heating stage was used for in situ observations of the microscopic effects of heating up to 1300 ºC. The effects of heating were observed at different temperature intervals in different samples. The main temperature intervals were below 573 ºC and above 1000 ºC. The cause of the observed effects is interpreted as fluid inclusion decrepitation for T<573 °C and structural implications (micro cracks, grain boundaries and remaining fluid inclusions) at T>1200 °C. Shock heating of the samples was carried out in an induction furnace to 1300 ºC for ten minutes. The effects of the heating were studied with different techniques such as direct observation during and directly after heating, optical microscopy and XRD. Combined transmitted and fluorescence light microscopy shows that the heated quartz show an opening of the grain boundaries and evenly distributed micro cracks that were not present in the unheated reference samples. In some of the heated samples, weak generation of cristobalite was detected by XRD.

Jan 1, 2007

By P. A. Lilly, W. Sarunic

In most cases, slope movement monitoring data are collected on a temporal basis and displacement or velocity is plotted against time in order to assist the engineer to make judgements about slope behaviour. Once an unusual behaviour pattern has been established, the data are then analysed to estimate when the key inflection points occur in the data, when the slope movements start to accelerate and, ultimately, when the slope is expected to collapse. The identification of these inflection points is sometimes difficult to achieve with the naked eye. This paper presents the application of a trend analysis technique, known as cusums, to assist in this process. The authors have presented a range of data from various real life examples which highlight the effectiveness of the cusums technique. A key aspect of the cusums technique is the use of a constant (K) against which data trends are assessed. This constant is best derived from slope performance data at each site, as each rock mass will behave in its own unique way. The authors have experienced slopes that have had threshold values ranging from 0.1mm/day through to 10mm/day, and therefore a conservative approach should be adopted when assessing the performance of slopes.

Jan 1, 2006

By B. Solar Menéndez, M. B. Díaz Aguado, I. Á. Fernández, C. González Nicieza

The analysis of subsidence due to the opening of an underground void (mining, water exploitation or civil works hole) is a problem usually hard to solve. First of all, it requires a predictive model, in order to define both the displacement magnitude and area affected by subsidence. Such model should be validated with measurements of the actual movements sustained on the surface, in order to adjust it properly and enable influence of future behaviour in a reliable way. Two different kinds of problems might arise. On one side, it is necessary to control and measure surface movements in a very exhaustive way during a long period of time, beginning before underground works take place and finishing years after they are over. Furthermore, three factors bring in errors, some times of magnitudes higher than the displacement magnitudes measured. These include: the fact that reliable and long-term information cannot always be achieved; the precision of measuring devices; and the design of the topographical network itself. In addition, the predictive models more widely used only apply to certain excavation geometries, mainly to horizontal holes. In light of this background, the Group of Rock Engineering, of the University of Oviedo Mining Department, has developed a working methodology and a specific software tool, Subsidence 3D, to estimate ground displacements and strains. The program will allow for predictive models to be defined and also allows the treatment of data related with topographical marks and its comparative analysis with calculated results. The software has been programmed using Visual C++. Graphical outputs however are generated using AutoCAD 2000. This paper mainly refers to a practical situation, an underground coalmine, remarking the main difficulties arisen during the study of the available information and proposing how to solve them. A predictive model in subsidence 3D was established and validated. The actual behaviour of the ground was that in the model.

Jan 1, 2003

By C. Dauber

Implementing new technologies in industrial operations entails the challenge of measuring the improvements gained by the applied technology. Nevertheless, it is absolutely essential to assess the technical and economic benefits in objective and comprehensible numbers to create a platform for further management decisions. Underground coal mines are characterized by numerous, quite complex procedures which make it difficult to determine the specific economic benefit of a new machine, technique, or method. In the OPTI-MINE Project funded by the European Union?s RFCS programme, five underground coal mines applied the latest information and communication technologies (ICTs) to improve efficiency, mine safety, occupational health, and environmental im-pacts. An integral part of the project is the assessment of these technologies by using key performance indicators (KPIs). The paper will describe some examples of the selected KPIs and the preliminary findings.

Jan 1, 2014

By Rodney Ishak, Merete Tangstad

In the HC FeMn production, better utilisation of coke and electric power is vital for reducing the production costs. The higher manganese oxides in the charge are reduced to MnO in the prereduction zone, where also the Boudouard reaction is active. These gas-solid reactions are to a large extent decisive for the total consumption of both coke and electrical power in ferromanganese production. In the present work formulas for calculating the Degree of prereduction have been developed for industrial practice. It shows that the typical Degree of prereduction is between 10-40%, but it may in good periods be as high as 60%. Statistical analysis has been done in order to find how various operational parameters influence the Degree of prereduction. A few parameters were observed to have an effect on the prereduction. Comilog ore definitely had a positiveinfluence on the prereduction, Comilog sinter and Mamatwan ore probably had a positive influence on the prereduction, all in relation to the average prereduction in the selected periods. Meanwhile, As man ore definitely, % H2O in raw materials and increasing Hd probably, had a negative influence on the prereduction. The findings for these raw materials were very much in coherence with the results of laboratory scale experiments performed, where the CO-reactivity of different ore materials was studied.

Jan 1, 2007

By T. R. Curr, R. T. Jones

Keywords: Pyrometallurgy, Mintek, DC arc furnace, plasma, smelting, chromite, ilmenite, cobalt, slag, zinc fuming, dust, magnesium, laterite, ferronickel, arc modelling, Pyrosim, thermodynamics The Pyrometallurgy discipline at Mintek was initiated in the early 1970s, to support a growing ferroalloy industry in South Africa. In addition to a range of pyrometallurgical options, Mintek specialises in DC arc furnace technology and has pilot plant facilities up to 5.6 MVA, as well as a strong base in process and arc modelling. Industrial processes have been developed for ferrochromium production, ilmenite smelting, and cobalt recovery from slag. Recent work has been done on such processes as the production of ferronickel from laterite ores, the fuming and condensation of magnesium, and the recovery of platinum group metals from &apos;difficult&apos; feedstocks.

Jan 1, 2006

1. Book reviews Nonparametric geostatistics, by S. Henley. London, Applied Science Publishers, 1981. xiv + 145 pp. Reviewer: Douglas M. Hawkins Mineral deposits and global tectonic settings, by A. H. G. Mitchell and M. S. Garison. London, Academic Press, Geology Series, 198!. Reviewer: J. Lurie The mining and mineral laws of South Africa, by B. L. S. Franklin and M. Kaplan. Durban, Butterworths, 1982. Cloth, 240 X 150 mm, Lxxcii + 853 pp. R197,50 + GST. Reviewer: M. J. Martinson Aluminium- Volume II, by M. H. Govett and J. Larsen. Sydney, Australian Mineral Economics (Pty) Ltd, 1982. Reviewer: D. G. Maxwell International technology for the nonferrous smelting industry, by Noyes Data Corporation. Reviewer: D. A. Viljoen 2. New publications Coaltransport- an analysis of technical and economic factors, by Dag Pike. London, Financial Times, 1982. £86 (D.K.), D.S. $175 (overseas including first class airmail postage). Small solute concentration differences determined by interferometry, by H.E.L.G. Schweigart. Pretoria, CERG-CSIR (P.O. Box 395, Pretoria), 1982. 3. Mintek reports Report M8A determination, using solid zirconia electrolytes, of the activities of chromium oxide in ferrochromium alloys and slags at 1650°C. Report M31Software for the design of multivariable control systems by use of the Inverse Nyquist Array. Report M37A literature survey of the metallurgical aspects of minerals in Witwatersrand gold ores.This survey reviews the information in the literature Report M 39 The use of masking agents in the determination, by hydride generation and atomicabsorption spectrophotometry, of arsenic, antimony, selenium, tellurium, and bismuth in the presence of noble metals. Report M40 The use of X -ray-fluorescence spectrometry in the determination of uranium, cobalt, and sulphur in materials from mine dumps. Report M44 A n on-line dilution system for spectrometry ustng an inductively coupled plasma source. Report M47 The separation of trace elements from iron, and the analysis of iron-rock ores for use as reference materials. Report M49 A programme in BASIC for the appending of computer files. Australian coal The editors of World Coal and World Mining have announced plans to sponsor the IVth International Coal Exploration Symposium. The symposium will be held in Sydney (Australia) from 15th to 19th May, 1983. Small mine economics The editors of World Mining and World Coal have announced plans to sponsor the Second International Symposium on Small Mine Economics and Expansion in Helsinki, Finland, from 12th to 16th June, 1983. The first symposium was held in Taxco, Mexico, in May 1981.

Jan 1, 1982

By J. P. Gous, J. J. Sutherland

"Transalloys is a silicomanganese (SiMn) producer located in South Africa, and uses only local manganese ores to produce SiMn alloy. The plant operates five open submerged arc furnaces (SAFs) with an annual capacity of 180 000 t of saleable SiMn.Maintaining tap-holes is critical for effective furnace operation, allowing proper drainage of the furnace with minimal operator interference. Using a claygun and drill arrangement installed at each furnace, tapping occurs every four hours. Tap-holes are maintained through mickey replacement and brick repairs. Three furnaces have SiC tap-holes and two have graphite tap-holes.This paper gives a review of SAF operation, furnace and tap-hole design, daily tapping operation, and maintenance practices for repairing tap-holes.IntroductionDefining tap-hole life cycle, Steenkamp et al., (2016) highlighted four main steps: installation during furnace relines, day-to-day operations, tap-hole maintenance, and tap-hole repair. The authors argued that the design of the tap-hole area should allow for all four stages in the tap-hole life-cycle. Design principles for each stage were presented using silicomanganese (SiMn) production as a case study. Here we present a further analysis of the case study by providing practical examples of how the tap-hole life-cycle is managed at Transalloys during the design, operation, and maintenance of submerged arc furnaces (SAFs) applied in the production of SiMn.BackgroundTransalloys is the largest producer of SiMn in Africa. Its smelter complex is based outside the town of eMalahleni, in the Mpumalanga Province of South Africa. Transalloys was commissioned in the mid- 1960s as a high- and low-carbon ferrochromium plant based on the Perrin process. In 1967 the plant was converted to SiMn production because of constraints in the ferrochrome market (Basson, Curr, and Gericke, 2007; Bezemer, 1995). Today, the installed production capacity is 180 000 t of SiMn annually. Plant operations consists of five SAFs (see ratings in Table I), operating 24 hours a day, 365 days a year (including maintenance), involving 280 permanent employees, with up to 120 contract employees on site at any given time."

Jun 1, 2019

By F. K. Mulenga, M. Lusambo

"Geometallurgical models are a strategic tool used primarily in planning, diagnosis, and process optimisation. This paper discusses the development of a predictive model for flotation recovery at Kansanshi concentrator in Zambia as a function of key operational parameters. Daily data for milling and flotation from the circuit processing the copper sulphide ore was analysed. This data, recorded over a period of one year of production, was collected from diverse sensors measuring semi-autogenous milling and flotation parameters. Statistical analysis showed that copper head grade, acid-insoluble, and acid-soluble copper, SAG mill throughput, ball mill load, and tonnage of feed material to the SAG mill in the -125 +63 mm size fraction contributed to the prediction power of the proposed empirical model by as much as 90%. Finally, a proposal was made for the development of a simulation model under MODSIM®, a flexible tool for mineral processing applications. This was to test the limitations of the empirical model for future refinement. IntroductionKansanshi is the largest copper mine in Africa and the world’s eighth largest copper producer, with a total of 253 272 t of copper produced in 2016 (Newall, 2017). It is located approximately 10 km north of Solwezi, the capital and administrative headquarters of the North Western Province, Republic of Zambia. The ore deposit consists predominantly of chalcopyrite and malachite with variable amounts of chalcocite, bornite, chrysocolla, and azurite. Because of the varying proportions of sulphide and oxide copper minerals, the ore is classified into three distinct categories: sulphide, mixed, and oxide ores. As such, three separate processing circuits are used to mill the ore down to a standard targeted grind size of 80% passing 150 µm before froth flotation and leaching.A lot of research and development has been done to improve the performance of the sulphide ore circuit at Kansanshi. Despite the research efforts and subsequent operation, the sulphide ore circuit did not attain the target recovery and grade for 2016, primarily because of the complexity of the orebody.The constant drive to achieve the set production target of recovery and concentration grade after froth flotation motivated the development of a tool for the prediction of recovery. The anticipated benefit is not only to enable the plant to apply corrective actions when needed, but also to make a tool available for the quick assessment of the plant performance of the. For that purpose, data spanning June 2016 to May 2017 was analysed, cleaned up and curvefitted to an empirical model. In doing so, key parameters were determined and calibrated to represent the behaviour of the plant."

Nov 1, 2018

By M. Wong-Kian, L. A. Cornish, A. van Bennekom

Samples of four different satellite materials were prepared by either hot isostatic pressing (HIP) of the powder or tungsten inert-gas welding of rod onto a 316 L stainless-steel substrate. The samples were subjected to a series of comparative erosion corrosion tests, and generally the Hipped samples experienced between 13 and 24 per cent less loss in mass than the equivalent welded alloys. Resistance to erosion corrosion increased with increasing carbon, chromium, and tungsten contents. Metallographic studies indicated the differences in carbide content between the different satellite materials, and the differences in morphology between the Hipped and welded samples. Finer and more homogeneous microstructures were

Jan 1, 1995