Anglo Research

Johannesburg, South Africa

Anglo Research

Johannesburg, South Africa

Time filter

Source Type

van Drunick W.,Anglo Research | Gerold C.,Loesche GmbH | Palm N.,Anglo Research
XXV International Mineral Processing Congress 2010, IMPC 2010 | Year: 2010

The work conducted in this paper followed a series of previous pilot trials at Anglo Research. The common objectives to all the work were to develop comminution circuits/fl owsheets that can produce liberated grind sizes at improved effi ciency of energy use. The 'Energy Effi cient Comminution' circuit would also need to be economical from a holistic point of view, and would therefore have to be favourable when all factors are taken into account - ie capital expenditure, operational expenditure, operability, sensitivity to feed variability, safety, relining time, etc. The progression of the work done at AR resulted in the piloting of a 'Cone Crusher-VRM' and 'HPGR-VRM' circuit at Loesche GmbH, using Gamsberg ore. The VRM has previously been identifi ed as an energy-effi cient comminution device, with the added benefi t of producing a dry fi nal product. A dry grinding product would allow one to be better positioned to accurately control the dilution rate (hence per cent solids) to the fl otation plant feed. The galvanic interaction of steel grinding media will also be reduced due to the elimination of grinding balls in the mostly autogenous HPGR-VRM set-up, thereby preserving the mineral surface chemistry.


van Staden A.,University of Johannesburg | van Staden A.,Anglo Research | Zimmermann U.,University of Johannesburg | Zimmermann U.,University of Stavanger | And 5 more authors.
Journal of the Geological Society | Year: 2010

The results of detrital zircon U-Pb geochronology suggest a maximum depositional age of 485 ± 7.2 Ma for a glacial diamictite from the Sierra del Volcán in eastern Argentina (Tandilia System). Earlier interpretations associated the deposit with the Neoproterozoic 'snowball Earth' hypothesis. The data allow direct correlation, for the first time, between Early Palaeozoic deposits in both South America and South Africa connecting the glacial deposits from southern Bolivia to central Argentina with those in South Africa (Pakhuis Formation). On the basis of these results, a new distribution map of glacial cover, corresponding to the Hirnantian stage, can be developed. © 2010 Geological Society of London.


Vanhaecke F.,Ghent University | Resano M.,University of Zaragoza | Koch J.,ETH Zurich | McIntosh K.,Anglo Research | Gunther D.,ETH Zurich
Journal of Analytical Atomic Spectrometry | Year: 2010

Owing to the shorter time interval during which energy is delivered to the sample material, femtosecond (fs) laser ablation is preferable over nanosecond laser ablation for metallic samples. In this project, the influence of various laser parameters - beam diameter, repetition rate and laser fluence - on the ablation of Pb as a heavy metallic matrix using an infrared (λ = 795 nm) fs-LA system (150 fs pulse duration) was studied. The merits of Ar and He as carrier gases were compared and as He did not provide a substantial improvement in the limits of detection, while deposition of sample material on the window of the ablation chamber was more pronounced, Ar was selected for all further measurements. The effect on the ICP caused by the introduction of various amounts of sample aerosol was studied by monitoring the signal intensity for 38Ar+. It was shown that maximizing the amount of sample ablated and thus, the amount of sample aerosol introduced into the ICP, did not result in maximum sensitivity, which was rather obtained under 'compromise' conditions. Subsequently, femtosecond LA-quadrupole-based ICP-mass spectrometry (ICP-MS) was used for the determination of traces of the platinum group metals (PGMs) Rh, Pd, Ru, Ir and Pt and of Au in Pb buttons obtained by fire assay of platiniferous ore reference materials. The signal of 204Pb + was used as an internal reference, correcting for variations in the laser ablation and transport efficiencies and in the instrument's sensitivity. The spectral interferences established for some of the target nuclides due to the occurrence of Pb2+ ions were successfully overcome by pressurizing the reaction cell with NH3. Quantification versus a calibration curve constructed on the basis of the results obtained for matrix-matched standards (> 99% Pb) provided excellent accuracy, superior to those obtained using nanosecond LA-ICP-MS. Also the limits of detection were improved by a factor ranging between 3 and 10 and are <0.010 μg g -1 for the most important PGMs (Rh, Pd, Pt) and Au. Several measures, such as the use of a large ablation cell and housing up to 10 Pb buttons, were taken to increase the sample throughput. In the same context, day-to-day reproducibility of the calibration curve was also examined. When recording a 'fresh' calibration curve every day, the average bias between the experimental results and the corresponding reference values was established to be <2.5% for every target element. When using one calibration curve during three consecutive days, the bias still remains <10%, while the sample throughput is increased and analysis of several tens of buttons per day is feasible (10-15 min total analysis time per sample). © The Royal Society of Chemistry 2010.


Palm N.,Anglo Research | Shackleton N.,Anglo Research | Malysiak V.,Anglo Research | O'Connor C.,University of Cape Town
XXV International Mineral Processing Congress 2010, IMPC 2010 | Year: 2010

The use of High Pressure Grinding Rollers (HPGR) has been widely reported to have major benefi ts in the treatment of minerals such as iron ore and diamonds. To date there have been few investigations into its use in the treatment of ores containing Platinum Group Minerals (PGMs). HPGRs are known to reduce energy consumption and wear costs and improve the throughput in the circuit. In the present investigation the effect of the comparative use of HPGR and conventional crushing in combination with either dry or wet rod milling on the fl otation of PGMs was studied using batch fl otation. Previous studies of a base metal sulfi de ores had shown that either HPGR or conventional crushing followed by dry milling produced the highest grades and recoveries. However in the present study it was observed that a similar treatment produced the worst results and the highest grades and recoveries were obtained for the case of conventional crushing in combination with wet milling. The HPGR showed no advantages in terms of fl otation performance and dry milling produced particularly poor fl otation results. The results were investigated further using various surface characterisation techniques in order to determine the reason for the decrease in grades and recoveries of platinum when using dry milling and HPGR as opposed to the case for base metal sulfi des. The feed and product samples were analysed using ToF-SIMS, XPS and MLA. The paper will propose reasons to explain the different fl otation behaviour of the two ore types following the various comminution processes focusing on the surface characteristics of the ores, the particle size distribution and the pulp chemistry.


Tonzetic I.,Anglo Research | Dippenaar A.,Kumba Iron Ore
Minerals Engineering | Year: 2011

An alternative to the traditional quantification of iron ore sinter mineralogy is presented through the use of QEMSCAN instrumentation. The classification of minerals by QEMSCAN is based on chemical composition whilst the traditional classification of iron ore sinter mineralogy, through point counting, is based on morphology. The classification of iron ore sinter minerals through XRD is based on crystal structure. Advantages of the QEMSCAN technique include the ability to distinguish magnesio ferrites from calcio magnetites and the fact that calcium ferrite and silico-ferrite of calcium and aluminium (SFCA) distinction is not dependant on the sectioning of the sample mount. © 2011 Elsevier Ltd. All rights reserved.


Palm N.A.,Anglo Research | Shackleton N.J.,Anglo Research | Malysiak V.,Anglo Research | O'Connor C.T.,University of Cape Town
Minerals Engineering | Year: 2010

High Pressure Grinding Rollers (HPGR) are known to reduce energy consumption and wear costs and improve the throughput in the circuit. It has been suggested that they can also modify the liberation characteristics of the ore. In the present study the effect of using conventional crushing as opposed to HPGR in combination with either dry or wet milling was investigated using a base metal sulphide, viz. sphalerite, in order to determine whether there may be an improvement in flotation performance following the use of different comminution procedures. It was found that, irrespective of the crushing procedure (HPGR or conventional), dry milling resulted in the highest grades and recoveries of zinc. These were typically 94% recovery at 40% grade. In order to gain an insight into the effect which these comminution procedures had on the ore, samples of feed and product were investigated using surface analytical techniques. Mineralogical analyses showed no differences in the liberation characteristics of sphalerite irrespective of the comminution procedures used. However, dry milling produced a lower d50. The paper proposes possible reasons to explain these observations. © 2010 Elsevier Ltd. All rights reserved.


Chapman N.A.,Anglo Research | Shackleton N.J.,Anglo Research | Malysiak V.,Anglo Research | O'Connor C.T.,University of Cape Town
Minerals Engineering | Year: 2011

The use of High Pressure Grinding Rollers (HPGR) has been widely reported to have major benefits in the treatment of minerals such as iron ore and diamonds. To date there have been few investigations into its use in the treatment of ores containing Platinum-Group Minerals (PGMs). HPGRs are known to reduce energy consumption and wear costs and improve the throughput in the circuit. In the present investigation the effect of the comparative use of HPGR and conventional crushing in combination with either dry or wet rod milling on the flotation of PGMs was studied using batch flotation. Previous studies of a base metal sulphide had shown that either HPGR or conventional crushing followed by dry milling produced the highest grades and recoveries (Palm et al.; 2010). However in the present study it was observed that a similar treatment of Platinum-Group Minerals produced the poorest results and the highest grades and recoveries were obtained for the case of conventional crushing in combination with wet milling. The HPGR showed no advantages in terms of flotation performance and dry milling produced particularly poor flotation results. The results were investigated further using various surface characterization techniques in order to determine the reason for the decrease in grades and recoveries of platinum when using dry milling and HPGR as opposed to the case for base metal sulphides. The feed and product samples were analysed using ToF-SIMS, XPS and MLA. The paper will propose reasons to explain the different flotation behaviour of the two ore types following the various comminution processes focusing on the surface characteristics of the ores, the particle size distribution and the pulp chemistry. © 2010 Elsevier Inc. All rights reserved.


Ilmenite (FeTiO3) is being explored as an oxygen carrier in chemical looping processes. Its reduction and oxidation are described by the system Fe-Fe2O3-TiO2-Ti2O3. The phase diagram at 1 000°C, presented here, offers a useful tool for predicting reactions and their products. We see that Fe2TiO5 (pseudobrookite) and TiO2 (rutile) form a stable phase assemblage following the oxidation of FeTiO3 (ilmenite) in air. The subsequent reduction of Fe2TiO5 at oxygen partial pressures of 10-15.5 atm stabilizes Fe1.02Ti0.98O3, a solid solution of ilmenite. Further reduction will produce metallic iron, which compromises the integrity of the oxygen carrier for chemical looping processes. We speculate that the reduction of Fe-Ti oxides in several practical instances does not reach completion (and equilibrium) under the imposed atmospheres operating in fuel reactors. © 2011, IFP Energies nouvelles.


Schouwstra R.,Anglo Research | De Vaux D.,Anglo Research | Hey P.,Anglo Research | Malysiak V.,Anglo Research | And 2 more authors.
Minerals Engineering | Year: 2010

The Gamsberg zinc deposit in the Northern Cape in South Africa has been the subject of a number of studies by Anglo American over the years. Two distinct ore types have been identified, namely pelitic and garnet-magnetite ore. The ore is characterised by relatively high manganese levels. Manganese reporting to the flotation concentrate is problematic for downstream refining. Anglo Research was asked by the exploration division of Anglo Base to study the relationship between the mineralogy and the floatability of the ore from reef intersections obtained from the eastern ore body. The two ore types were found to have different mineralogical characteristics resulting in different flotation responses both in terms of zinc and manganese recoveries and concentrate grades. The presence of the manganese sulphide, alabandite, was also established, and was found to be extremely detrimental to sphalerite flotation. The reasons for this were explained using the surface analysis facility at Anglo Research. © 2010 Elsevier Ltd. All rights reserved.


Viljoen F.,University of Johannesburg | Viljoen F.,De Beers Geoscience Center | Dobbe R.,FEI Electronic Optics B.V. | Harris J.,University of Glasgow | Smit B.,Anglo Research
Lithos | Year: 2010

Although diamonds of eclogitic paragenesis are commonly encountered in the productions of many Southern Africa kimberlites, the nature and evolution of the protolith to eclogitic diamonds are still poorly understood. There is some evidence that these protoliths (and possibly also the diamonds) may be related to subduction of oceanic crust, although this is not a universally accepted view. In order to further investigate the protolith/diamond relationship, garnets and (in some cases) clinopyroxene inclusions in 23 diamonds from Premier mine and 16 diamonds from Finsch were analysed for their trace element composition. From both mines a strong correlation between the garnet Ca content and the chondrite-normalised rare earth element (REE) pattern is evident. Garnets with comparatively low Ca content are characterised by REE patterns which show a steady increase in abundance from light rare earths (LREE) to heavy rare earths (HREE). With increasing Ca content in garnet, the abundance of LREE (La, Ce, Pr, and Nd) as well as the middle rare earths (MREE; Sm, Eu, Gd, and Tb) progressively increases, ultimately giving the trace element pattern a distinct 'humped' appearance. Bulk-rock trace element abundance patterns have been reconstructed from measured trace element contents in garnet as well as calculated trace element concentrations in clinopyroxene, based on known clinopyroxene-garnet partition coefficients (Harte and Kirkley, 1997). At both Premier and Finsch, the low-Ca group samples (2.6 to 5.0. wt.% CaO in garnet) are LREE depleted, and have relatively flat calculated bulk-rock trace element abundance patterns at approximately 10 times chondrite concentrations, but with marked positive Sr and negative Zr anomalies. The intermediate-Ca group samples (5.2 to ~9. wt.% CaO in garnet) are LREE depleted, show Sr and Zr anomalies, have somewhat higher concentrations of Zr and MREE, and have HREE contents that overlap with the low-Ca group (Fig. 6). High-Ca group samples (~. 9 to 14.8. wt.% CaO in garnet) are LREE depleted, show Sr and Zr anomalies, are MREE-enriched, and have HREE contents that are slightly less than the low- and intermediate-Ca group samples. Based on both the calculated bulk eclogite trace element abundances and their patterns, as well as previously published radiogenic isotope data, our preferred model of protolith evolution for the eclogitic diamonds from Premier and Finsch is one in which both the major and trace element chemistry of the inclusions are ultimately inherited from low-pressure oceanic protoliths, consisting of varying mixtures of oceanic basalt. +. cumulate gabbro for diamonds from both Premier and Finsch. Of particular importance in the current data are the presence of marked negative Zr anomalies, marked positive Sr anomalies, and a general absence of Eu anomalies in all compositional groupings. The Zr anomaly can arise in reconstructed bulk eclogite trace element abundance patterns if rutile is not included in the calculations, but the Sr anomalies (coupled with an absence of Eu anomalies) can only be explained through the mixing of oceanic gabbro and mid-ocean ridge basalt. The averaged eclogite bulk trace element compositions for Premier and Finsch are also markedly similar to that of clinopyroxene in a typical cumulate gabbro, and a role for cumulate clinopyroxene in protolith evolution may therefore also be inferred. It is likely that prior to and during diamond crystallisation, the major and particularly the trace element compositions of the high-pressure eclogite source rock to these diamonds may have been slightly modified by metasomatic fluids and melts. However large-scale fluid- or melt-related metasomatic processes are not indicated. © 2010 Elsevier B.V.

Loading Anglo Research collaborators
Loading Anglo Research collaborators