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By R. V. Peche

Since 1952, Bond’s equation has been used as a standard to predict the specific energy of grinding for a given duty. The Bond’s equation considers that the exponent is constant for all conditions. Hukki, in 1961, pointed out that the exponent is a function of the particle size, and concluded that the Bond’s equation applies successfully for an intermediate range of sizes; out of this range the Bond’s equation leads to high error as demonstrated in this paper. More recently, in 2004, S. Morrell presented a new formula in which the exponents vary with the feed and product size. This paper is based on Hukki’s approach and presents a new general formula, in which the exponent varies only with the feed particle size. This new equation has been proven in 82 observable cases in Peru and other countries around the world, involving ball mills and vertimills in different configurations over a wide range of feed and product sizes, work indices and mill diameters; in most cases, the predicted value has an error less than 10% with regards to the observed value and no need for any correction factor. Keywords: Grinding, specific energy, particle size, work index, variable exponent

Jan 1, 2020

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. C. Vreugdenburg, B. A. Dippenaar, J. Muller, T. L. de Vries

Iron ore fines are agglomerated in the sintering process to produce sinter: an important feed material for blast furnaces worldwide. A model of the iron ore sintering process has been developed with the objective of being representative of the sinter pot test, the standard laboratory process in which the behaviour of specific sinter feed mixtures is evaluated. The model aims to predict sinter quality, including chemical quality and physical strength, as well as key sinter process performance parameters such as production rate and fuel consumption rate. The model uses the finite difference method (FDM) to solve heat and mass distributions within the sinter pot over the sinter bed height and time dimensions. This method can further be used for establishing empirical relationships with measured sinter properties. Inputs into the model include the feed material physical properties, chemical compositions, and boundary conditions that vary over time. Sub-models describe relationships between applied pressure differential and gas flow rate through the bed of granulated fine ore particles, combustion of carbonaceous material, calcination of fluxes, evaporation and condensation of water, and melting and solidification. Four sinter pot tests were performed and the model predictions validated against temperatures measured at depths of 100, 230, and 420 mm. Differences between predicted and measured temperatures indicated the need for optimization of some model parameters that are uncertain. Optimization resulted in an improvement in the correlation between the predicted and measured temperatures for all tests, although an acceptable level of agreement was not achieved in all cases. Using these parameter values, reasonable agreement was found in terms of typical performance parameters for three out of the four tests.

Jan 1, 2014

By M. Rudolph, A. D. Renno, H. Wu

In this study, synthetic pure cassiterite and cassiterite doped with Fe were successfully produced by sintering. Their crystal structure and chemical compositions are characterised by optical microscopy, X-ray powder diffraction (XRD) as well as scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) based chemical composition analysis. The electrostatic behaviour of synthetic and natural cassiterite was studied by electrophoretic measurements. Their floatability was studied by microflotation with two types of anionic collectors. Results show that the cassiterite floatability with these collectors behaves differently and lead to two opposite results: Natural cassiterite (enriched with Fe) > undoped pure SnO2 by using sulfosuccinamate (Aerosol® 22) Undoped pure SnO2 > Fe3+ doped > natural cassiterite (enriched with Fe) by using styrene phosphonic acid (SPA). Keywords: Synthetic cassiterite, lattice impurities, flotation, zeta potential, Aerosol® 22, styrene phosphonic acid

Jan 1, 2020

By S. Burks

This paper develops the themes explained at the previous SAIMM Platinum conference by Whittle and Burks1. Optimization techniques can be used to significantly increase the value of mining businesses by enabling better long- term planning decisions. Open pit and underground mine design, mine scheduling, cut-off grade and blending, stockpiling, and the linking of these to flexible elements of the metallurgical recovery processes are all evaluated together. Transport or sale of intermediate products and the requirements of the product metal markets can also be considered. Experience shows that net present value (NPV) can potentially be increased by 5-35 per cent or more, usually even before the expenditure of significant amounts of project capital. The case studies presented include: ? An existing operation with multiple open pits and PGM concentrators linked to offsite downstream processing facilities, and with infrastructure constraints for which the scheduling of current operations and the potential for expansion were investigated ? An existing operation with an integrated portfolio of mines, concentrators, smelter and refinery, for which the various possible sources of ore for processing were prioritized to match the downstream process plant constraints and the product markets ? An underground operation in Zimbabwe for which the optimum mining width was calculated and expansion plans were evaluated ? An underground mine with many separate mining sections, for which a revised schedule was developed aiming to keep the shaft system and processing plant at capacity with the highest net value material available at any time throughout the life of mine. In the concluding section of the paper, a few brief notes are included suggesting how the strategic recommendations from enterprise optimization studies may be implemented by the Owner?s team.

Jan 1, 2012

By A. M. Garbers-Craig, T. Coetsee, T. M. Nemavhola

Accretions often form in furnaces when slag and charge materials attach to the refractory wall and build up over time. Accretion formation is usually unwanted because it reduces the working volume of the reactor and hinders material flow through the reactor. However, in some instances a thin, stable accretion layer may be desirable to protect the underlying refractory material. In order to prevent and/or manage accretion formation, it is important to understand the underlying principles of this phenomenon in the particular reactor. Excessive accretion formation hampered production at the Exxaro FerroAlloys ferrosilicon melting and atomization plant. This plant uses induction furnaces in which a 15% silicon-iron alloy is produced by batch smelting a mixture of ferrosilicon of 75%Si grade and low-carbon steel. The molten ferrosilicon alloy is then gas-atomized to a powdered product for use as a dense medium in mineral processing plants. The objective of this study was to investigate the effect of different impurity levels in the ferrosilicon feed material on the extent of accretion formation as well as the effect on the accretion properties, which influence the ease of accretion removal upon furnace shut-down. Refractory and accretion samples were collected after a furnace shut-down and characterized using X-ray diffraction and scanning electron microscopy–energy dispersive spectroscopy. It was concluded that the trace elements in the FeSi-75 feed material (Al, Ca, Mn) were mostly responsible for accretion formation, but that rust on the low-carbon steel and oxidation of the steel contributed to accretion attachment to the lining. The total contaminant content, calcium to aluminium ratio in the FeSi-75 feed material, and thereby the liquid to solids ratio in the accretion at temperature determine the strength of attachment as well as growth of the accretion.

Feb 2, 2021

By S. Dey, C. Bhar, S. K. Mandal

Loading and hauling of ore and waste are the key operations of an opencast coal mine and entail a high operational cost. The productivity of a mine can be increased by reducing the cycle time of loading equipment as well as utilizing dumpers optimally. In this paper we discuss the impact of rock type, bucket fill factor, rock fragmentation, the height of the cut, and angle of swing of the bucket on shovel performance. A time study is conducted on shovels in an opencast coal mine with experimental blasts of rocks to assess the impact of different factors on the performance of the shovel. Based on the data, the authors applied multiple regression (MR) and artificial neural network (ANN) techniques to develop different models for the prediction of the shovel cycle time. Developed models are validated by comparing the predicted data with actual field data. With the help of the best model, the plausible fleet size is determined in order to utilize the shovel and dumper optimally and to improve the performance of shovel–dumper operation.

Oct 1, 2022

By M. Fener, S. Kahraman, O. Gunaydin, M. Alber

Falling into the weak rocks category, fault breccias have extremely poor engineering properties. These pebbles typically cause issues with slopes, subterranean construction, and building projects. Professionals will benefit from the creation of some predictive models for fault breccia triaxial strength, as smooth specimen preparation is typically challenging and timeconsuming. The purpose of this study is to develop some predictive models for the differential stress (Δσ) based on physical and textural properties. Artificial neural networks were used to analyse data related to Misis fault breccia. Initially, models with moderate (noticeable, but not good) correlation coefficients were created using multiple regression analysis. After that, the regression models and three distinct artificial neuron network models were contrasted. Regression models are weaker and less trustworthy than artificial neuron network models, as demonstrated by this comparison. Pointed out is the practicality and ease of use of the artificial neuron network model with S-wave velocity and volumetric block proportion. Ultimately, it can be concluded that artificial neuron networks analysis provides a reliable indirect method for predicting the differential stress of Misis fault breccia.

Sep 1, 2025

By F. T. Cawood, T. Chikande, H. R. Phillips

Underground mines require electricity to operate both the main surface fans and auxiliary systems, with primary ventilation systems typically accounting for approximately 40–60% of the mine’s overall electricity consumption. The primary reason for this considerable expense is that most underground ventilation systems are designed for peak demand, regardless of the actual demand, which is commonly dictated by diesel equipment usage in trackless mining operations. Most platinum mines on the Great Dyke in Zimbabwe tend to operate their ventilation systems at this peak level, despite the mine’s air quantity being well in excess of the ‘true’ ventilation needs. This is due to a lack of appropriate ventilation controls. The authors designed and installed a ventilation-on-demand system at one of the bord and pillar platinum mines to minimize the use of redundant air in underground operations. Fourth industrial revolution techniques were applied to the environmental monitoring and tracking systems thereby optimizing air quantity demands. The mine managed to reduce its annual power consumption by 23% through the implementation of manual control and time-of-day scheduling levels of the ventilationon- demand concept. There was also a 6% productivity improvement, mainly attributable to an increased face time as a result of the significant reduction in the re-entry period following a blast. This paper introduces a novel concept of ventilation optimization through digital transformation targeting mainly room and pillar platinum mines. A system was designed, installed, and commissioned, though there is currently an ongoing optimization process to harness the full benefits such as productivity enhancement, reduced power costs, and improved worker health.

Dec 13, 2022

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 M. Z. Emad, N. Abbas, Y. Majeed

Room-and-pillar mining is commonly employed for the extraction of rock salt in undergroundmines. Pillar stress is a major concern in these mines as it is directly related to stability and mineralrecovery. In this study a flat jack method was used to measure pillar stresses in three undergroundrock salt mines in Pakistan. The field work included determination of in-situ stress, in-situ elastic modulus, recording of field variables (pillar length and width, height and width of opening, opening width to height ratio, extraction ratio, and overburden height) and collection of salt block samples. The geomechanical properties of rock salt (uniaxial compressive strength, Young’s modulus, Brazilian tensile strength, and density) were also determined to estimate overburden stress, pillar strength, and factor of safety (both estimated and actual). It was found that the measured pillar stresses are proportional to the overburden stress values, with their magnitude ranging from 6.05 MPa to 11.97 Mpa, and the pillars were found to be stable. Regression analysis was performed to develop statistical models for in-situ stress and in-situ elastic modulus. Finally a quick guideline chart was developed to determine the suitable length of pillar for a given span and required level of safety.

Jun 5, 2023

1. Book review Technology of metal powders- recent developments, edited by L. H. Yaverbaum. New Jersey, Noyes Data Corporation, 1980. 400 pp. (Reviewer: B. K. Loveday) 2. New books The use of microprocessors, by M. Aumiaux. New York, Wiley, 1980. 176 pp. $25,50. Aluminium smelter technology, a pure and applied approach, by K. Grojtheim and B. J. Welch. Diisseldorf, Aluminium-Verlag GmbH (P.O. Box 1207, D-4000, Federal Republic of Germany). 146 pp. DM48. Coal-bridge to the future. New York, Harper & Row, 1980. $35. System modeling and response.. theoretical and experimental approaches, by O. Doebelin. New York, Wiley, 1980. 576 pp. $26. Environmental and climatic impact of coal utilization, edited by J. J. Singh and A. Deepak. New York, Academic Press, 1980. 646 pp. $39,50. Proceedings of the Third European Conference on Mixing, York, England, April 1979, edited by H. S. Stephens and C. A. Stapleton. BHRA Fluid Engineering (Cranfield, Bedford Mk43 OAJ, U.K.), 1980. 2 volumes. 500 pp. $50. Lignite technology, edited by P. Nowacki. New Jersey, Noyes Data Corporation, 1980. 228 pp. $42. The application of rock mechanics to cut-and jill mining. London, Institution of Mining and Metallurgy, 1980. Papers presented at the Fifth International Symposium on Jet Cutting Technology, Hanover, Federal Republic of Germany, June 1980, edited by H. S. Stephens and B. Jawis. BHRA Fluid Engineering (Cranfield, Bedford Mk 43 OAJ, U.K.), 1980. 438 pp. £38. World coal resources.. methods of assessment and results, by G. Fettweis. Amsterdam, Elsevier, 1979. 425 pp. $80,50. Geophysical and geochemical techniques for exploration of hydrocarbons and minerals, edited by M. Sittig. New Jersey, Noyes Data Corporation, 1980. 300 pp. $40. Financial Times mining international year book 1980. Longman Group Ltd (Periodicals and Directories Division, Longman House, Burnt Mill, Harlow, Essex CM20 2JE, England). £24 surface, £34 airmail. National Symposium on the Availability of Strategic Minerals, edited by M. J. Jones. London, Institution of Mining and Metallurgy, 1980. 109 pp. 3. NIM reports Report No. 1941 The recovery of chromite and platinum from the UG-2 Upper Chromitite Layer .of the Bushveld Complex at the Pandora Mine (first published 10th Mar., 1978). Report No. .2012 A mineralogical investigation of borehole cores from the Trompsburg Complex (first published 6th Apr., 1979). Report No. 2038 The leaching of sphalerite in acidic ferric sulphate media in the absence of elemental oxygen. Report No. 2052 An investigation of the impurities in native gold by neutron-activation analysis. Report No. 2056 The mineralogy and geochemistry of the copper, lead, and zinc sulphides of the Otavi Mountainland. Report No. 2058 A n elementary introduction to image analysis - a new field of interest at the National Institute for Metallurgy. Report No. 2059 Distributed computer control of industrial processes. Report No. 2060 The analysis, by atomic-absorption spectrophotometry, of activated charcoal.

Jan 1, 1980

By A. Singh, R. D. Govender

The current method employed to quantify the efficiency of separation of ferromagnetic ores by wet low intensity magnetic drum separators (WLIMS) incorporates the use of a conventional benchscale Davis Tube (DT) operating at a magnetic field intensity that is equivalent to that of the drum’s surface. However, empirical research has indicated that the magnetic force, or force index, rather than the magnetic field intensity, is the critical factor in the operation of the magnetic separator (Murariu and Svoboda, 2002). Furthermore, the current aforementioned practice would yield incorrect information as the magnetic field gradients produced by a typical WLIMS unit differs considerably from that of a bench-scale DT. In light of this, research on magnetite focusing primarily on the scale-up of DT results to pilotscale WLIMS were undertaken. The investigation entailed a comparative study between that of a typical WLIMS circuit and a bench-scale DT. The purpose was to practically evaluate the performance of a WLIMS, bench-marked against the traditional laboratory-scale DT unit. Moreover, the secondary objective was to produce a magnetite concentrate graded at 69% Fe, 95% -45μm, as a suitable source of separation media for use in the Dense Medium Separation (DMS) industry. Fundamental findings of previous works provided a framework for the study, however, a realworld approach was explored. Preliminary testwork conducted at Mintek investigated the performance of a DT and a typical multi-stage laboratory-scale WLIMS circuit (operating at 1000 Gauss at the surface). The results attained indicated that a DT operating at high intensities is comparable to a single rougher WLIMS stage. Additionally, it was observed that the three stage laboratory-scale WLIMS circuit performed similarly to the DT operating at 1000 Gauss. Moreover, piloting testwork was undertaken, carried out in larger 380mm drums, and the results attained showed a strong correlation with laboratory-scale findings. Keywords: Davis Tube, wet low intensity magnetic separation, magnetite

Jan 1, 2020

"Chairman: Dr W. S. RAPSON Rapporteur: Mr J. W. WILSONPapers:Computer applications in rock mechanics by F. H. Deist, E. Georgiadis and J. P. E. Moris Rock mechanics in the design of mine layouts by K. Hodgson and N. G. W. Cook Automated regulation of mine ventilation by P. NiskanenThe rock mechanics papers, because of their complementary nature, were presented in succession and discussion on both followed directly. The paper on automated ventilation control at a mine in Finland was then presented and the session was closed with several contributions to this paper.By and large the papers and discussions which followed in this session showed how a classic tie-up had developed between the use of computing techniques in important fields of mining, and their practical application. In fact, the dis-cussion following the rock mechanics papers showed clearly that without the aid of high-speed digital computers the rate of progress in applied research in deep-level hard-rock mines, would have been severely hindered. Furthermore, it became apparent from the comments made by several contributors that the rock mechanics techniques and computer progress described in Deist's and Cook's papers could be used to provide useful data in the solving of rock mechanics and design problems on mines other than flat dipping deep tabular deposits.The paper by Niskanen, which described an automated ventilation control system at a mine in Finland, showed how effective computers could be in areas where the reversal of mine ventilation occurs due to severe seasonal temperature ranges. Although the system described in the paper could not be introduced easily in complex underground mines, several contributors gave examples of similar ventilation problems that could be solved mechanically,In introducing his paper, Dr Deist said that the purpose of the paper was to give a brief account of some of the programs designed by himself and his co-authors to aid in the solution of rock mechanics problems,The first system presented by Dr Deist was known as MINSIM in the South African mining circles. This system was designed specifically to aid in the solution of rock mechanics problems in the South African gold mining industry. It was particularly designed to handle tabular deposits at great depth but it has been used satisfactorily on a number of occasions to obtain at least approximate solutions in other mining situations. Dr Deist said that the principles embodied in the programs were easily extended and, in fact, there was a project in progress at that time which was aimed to do this. He said that the principles could easily be extended to shallow-depth mining at steep or very steep inclinations."

Jan 1, 2014

By Y. R. Murthy, S. Angadi, A. K. Bhatnagar, S. K. Tripathy, L. O. Filippov

Dolomite is an essential raw material for the refractory industry, a flux in the iron and steel industry and also for the extraction of magnesium metal. Generally, particle size reduction, screening and classification are used for the preparation of the high-grade sized material for different applications, whereas low-grade fine fractions are not utilised. These fines or low-grade overburdens are dumped at the mine site for future utilisation, which creates environmental issues along with inadequate space management. In the present investigation, a detailed study was carried out to decrease the silica content of the low-grade dolomite fines from Gomardih , India, containing 28.6% CaO and 20.1% MgO along with 8.3% silica. Different process flow sheet options were evaluated with a combination of dry classifier, wet classifier, gravity concentrators as well as flotation. Different process variables were assessed along with mineralogical characterisation to optimise the process for efficient rejection of siliceous gangue minerals. Results indicated that dolomite, calcite and quartz are the major mineral phases present in the ore along with other minor minerals. It was concluded that two-stage flotation was an effective process for the reduction of silica up to below 1% after grinding to a particle size below 212 μm. A process flow sheet with a combination of gravitation air classifier and flotation can produce a concentrate with silica content below 4.5%. Keywords: Dolomite, flux, dry classification, flotation, characterisation, beneficiation

Jan 1, 2020

By B. Mbuya, A. F. Mulaba-Bafubianda, J. M. Mvita

The paper explains the main effects of input leaching parameters, such as addition of a reducing agent, acidity, agitation, temperature, and leaching system potential, in relation to observed and predicted yields of sought-after cobalt. An artificial neural network coupled with graphical probability networks was developed wherein the abovementioned input parameters were used to predict the percentage of dissolved cobalt. Furthermore, similarities and differences between the Bayesian and neural network approaches in terms of their key outcomes are compared with respect to study of the dissolution of cobalt in sulfuric acid. Key results indicate that there is a need to use neural network results to predict conditions for dissolution of cobalt, while using Bayesian network to explain inferences about conditions of the input parameters, thereby achieving realistic predictions.

Jan 1, 2023

By A. M. Venter, C. W. Siyasiya, N. K. K. Arthur, M. G. Willemse, D. Marais

Although additive manufacturing is fast gaining traction in the industrial world as a reputable manufacturing technique to complement traditional mechanical machining, it still has problems such as porosity and residual stresses in components that give rise to cracking, distortion, and delamination, which are important issues to resolve in structural load-bearing applications. This research project focused on the characterization of the evolution of residual stresses in Ti-6Al-4V extra-low interstitial (ELI) additive-manufactured test samples. Four square thin-walled tubular samples were deposited on the same baseplate, using the direct energy deposition laser printing process, to different build heights. The residual stresses were analysed in the as-printed condition by the neutron diffraction technique and correlated to qualitative predictions obtained using the ANSYS software suite. Good qualitative agreement between the stress measurements and predictions were observed. Both approaches revealed the existence of large tensile stresses along the laser track direction at the sections that were built last, i.e., centre of the top layers of the samples. This in addition leads to large tensile stresses at the outer edges (corners) which would have the effect of separating the samples from the baseplate should the stresses exceed the yield strength of the material. Such extreme conditions did not occur in this study, but the stresses did lead to significant distortion of the baseplate. In general, the microstructures and spatial elemental mapping revealed a strong correlation between the macro-segregation of elemental V and the distribution of the β-phase in the printed parts.

Feb 6, 2023

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 C. Ndou, T. Mothupi, H. Mandende

The technological advances in efficient, rapid, and non-destructive hyperspectral core logging systems for systematic mineral mapping have led to the discovery and exploitation of new mineral deposits Hyperspectral imaging in the long-wave infrared range has been recently used successfully to identify various phosphatebearing minerals (monazite, xenotime, and britholite), with limited work on apatite associated with mafic-ultramafic layered intrusions. In this study we investigate the effectiveness of a hyperspectral imaging (HSI) system with long-wave infrared (LWIR) bandwidthsto identify apatite in the Upper Zone of the Bushveld Complex. The accuracy of the HSI results was validated by mineralogical and geochemical data. The two apatite-enriched zones detected by HSI suggesting widespread development of apatite throughout the uppermost 600 m of the Upper Zone. The lower apatite-enriched zone is approximately 40 m thick, while the upper apatite-enriched zone is about 23 m thick, consistent with previous thickness determinations by traditional logging and analytical methods. Spectral mixing observed in the response of apatite is ascribed either to the common association of apatite and olivine in these rocks, or to differences between the spatial resolution of the hyperspectral image and the size of apatite grains. The VNIR-SWIR wavelength region did not show prominent spectral features of apatite. Nonetheless, HSI in the LWIR range is effective in mapping apatite and should therefore be considered as an exploration tool. This research advances our knowledge of the reflectance spectroscopy of REE-bearing minerals, which makes it easier to detect, identify, and quantify REE-bearing silicate minerals by HSI.

Feb 6, 2023

By Wei Sun, Ruolin Wang, Wenjuan Sun, Junhao Fu, Haisheng Han, Zhao Wei

Pb–benzohydroxamic acid (BHA) (lead complexes of benzohydroxamic acid) exhibits high selectivity but low collecting efficiency in scheelite flotation. This paper reports the manner in which BHA and sodium dodecyl sulfate (SDS) were employed as ligands to coordinate with the lead ions to obtain a colloidal lead-group multiple ligand complex, i.e., the Pb–BHA–SDS, for improving the collecting efficiency of Pb–BHA. The flotation mechanism of Pb–BHA–SDS with respect to scheelite was investigated from the viewpoint of interface science based on the pure mineral flotation, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results showed that the BHA and SDS coordinated with Pb2+ to form novel leadgroup multiple ligand complexes, which are different from the traditional understanding associated with the mixed collectors. Pb–BHA–SDS was a better collector with stronger collecting ability and excellent selectivity in regard to a scheelite flotation than Pb–BHA. The addition of SDS to Pb–BHA enhanced the latter’s adsorption ability on the scheelite surface and improved the hydrophobicity of the collector’s nonpolar groups, rendering Pb–BHA–SDS as a more efficient collector at a low dosage. Keywords: Scheelite; Pb-BHA complexes; sodium dodecyl sulfate; multiple ligands; Pb–BHA–SDS

Jan 1, 2020