Papers by Massimiliano Zanin
Minerals, 2016
One of the water constituents that has not been investigated in great detail for potential detrim... more One of the water constituents that has not been investigated in great detail for potential detrimental effect on mineral flotation is organic matter. This study investigates the effect of natural organic materials contained in water, such as humic, fulvic and tannic acids, on the flotation of copper and molybdenum sulphides in alkaline conditions and in concentrations similar to those found in natural waters. Results show that copper and molybdenum grades decreased with the addition of humic, tannic and fulvic acid in that order, with a larger depression of molybdenite grade and recovery. Adsorption studies using ultraviolet (UV)-visible spectroscopy and X-ray photoelectron spectrometer (XPS) surface analysis confirmed that these organic materials were adsorbed on the minerals surface. Complimentary analyses of froth characteristics, particle size distribution and fine particles entrainment were also conducted to explain the cause of the negative effect of these organic materials on flotation. The flotation results were explained in terms of the decrease in the hydrophobicity of the mineral surfaces due to the adsorption of hydrophilic groups in these organic materials which then prevent bubble-particle adhesion. The larger detrimental effect of humic acid is due to its higher adsorption on the minerals, high molecular weight and carbon content compared with the other organic acids used.
Advanced Powder Technology, 2012
Froth stability plays a major role in determining the mineral grade and recovery in flotation ope... more Froth stability plays a major role in determining the mineral grade and recovery in flotation operations, and it depends on the type and amount of both frother and suspended particles. Furthermore, there are other parameters such as quality of the process water which may affect the froth stability. In plant practice, the recycling of process water instead of using fresh water is increasingly being common. However, using recycled water normally leads to building up salts and surfactants in solution. Therefore, the effect of the process water chemistry on froth stability and metallurgical performance is important. In this study, the effect of water quality, including pH, and type and concentration of salts (CaCl 2 , AlCl 3 and NaCl) on froth stability and its relationship with mineral particles zeta potential and slurry viscosity was studied. It was found that the forth stability is higher in the presence of multivalent metal ions. Addition of CaCl 2 and AlCl 3 considerably increased both froth stability and pulp viscosity. This may be due to bridging effect of polyvalent metal ions between the ore particles.
Rem: Revista Escola de Minas, 2012
O objetivo desse trabalho é apresentar e discutir a determinação dos parâmetros de dispersão de a... more O objetivo desse trabalho é apresentar e discutir a determinação dos parâmetros de dispersão de ar em células mecânicas de flotação, em circuitos industriais brasileiros. Foram investigados os circuitos rougher e scavenger das usinas RPM, Taquari-Vassouras, Copebras e Fosfértil-Catalão (atual Vale Fertilizantes). Nas usinas RPM e Taquari-Vassouras, foram determinados a velocidade superficial do ar (Jg), o hold-up do ar (εg), o diâmetro médio de bolhas (d32) e o fluxo de área superficial de bolhas (Sb). Para as outras usinas, foram determinados somente o Jg e εg. Os resultados mostraram que, com exceção da RPM, todos os circuitos investigados apresentaram baixos valores para os parâmetros de dispersão do ar. Taquari-Vassouras apresentou os mais baixos valores médios para Jg e εg, respectivamente, 0,05 cm/s e 5%. Os maiores valores de Jg foram determinados no circuito rougher da Copebras, 1,17 cm/s, ao passo que a RPM apresentou os maiores valores para o hold-up e tamanho de bolha, re...
Minerals Engineering, 2019
This work is part of an ongoing investigation being conducted to recover and upgrade rare earth e... more This work is part of an ongoing investigation being conducted to recover and upgrade rare earth elements (REE) minerals from iron oxide and silicate rich tailings generated at a South Australian mining operation. Detailed mineralogical characterisation via Quantitative Evaluation of Minerals by Scanning electron microscopy (QEMSCAN) of the tailings established the presence of low grade (< 1 wt% REE), fine-sized REE minerals. The REE minerals (bastnäsite, monazite, florencite, stillwellite, brannerite, and stetindite) identified were in intimate associations with weakly ferromagnetic/strongly paramagnetic iron oxides (mainly hematite and goethite) and diamagnetic silicate (quartz, illite, and annite) minerals. Chemical analysis showed the tailings comprised 26.2% Fe, 18.6% Si, 3.9% Al, and 1.07% total rare earth oxides (TREO). A rougher-scavenger-cleaner magnetic separation process was deployed to produce two useful streams of REE minerals concentrate and tails using a wet high-intensity magnetic separator (WHIMS). Typical metallurgical results indicated the rejection of 25% of the iron oxides at 0.11 T, whilst producing a magnetic concentrate with TREO recovery of 51% at a grade of 1.25% and non-magnetic tails with TREO recovery of 41% at a grade of 1.08%, both at 1.74 T. Bastnäsite, monazite, florencite, and stillwellite minerals were confirmed to be paramagnetic, whilst stetindite and brannerite were found to be diamagnetic. Whilst the applied magnetic field intensity was the most important factor in the minerals' magnetic separation efficacy, particle size distribution and mineralogical characteristics of ores also had significant effect. The findings exemplify both the challenges and opportunities for the beneficiation of complex, low grade REE-bearing iron oxide silicate rich tailings using WHIMS. They indicate that magnetic separation may be used to achieve modest preconcentration, the success of which is limited by the complex nature of the tailings and its concomitant magnetic properties, and thus warranting the need for further downstream processing (e.g., froth flotation) to produce cleaner, higher grade REE minerals concentrates for subsequent values extraction.
Advanced Powder Technology, 2012
International Journal of Mineral Processing, 2015
In minerals beneficiation, the mineral liberation spectrum of the plant feed is valuable informat... more In minerals beneficiation, the mineral liberation spectrum of the plant feed is valuable information for adjusting operations, provided the information is available in minutes from particulate sampling. X-ray micro-tomography is the only technique available for unbiased measurement of composite particles composition (on a 3D basis). The bottleneck of current micro-tomographic systems is the X-ray scanning time (data acquisition) rather than the slice reconstruction time (data processing). An algorithm capable of reconstructing tomographic slices of composite mineral particles from a limited number of radiographic projections, and Highlights. X-ray tomography is a promising tools for un-biased mineral liberation studies. A reconstruction method that uses few projections for generating a slice is proposed. An original approach is used and the reconstruction solved by binary programming. The scanning-time is cut and mineral liberation data generated in shorter time. Results of numerical experiments are compared to traditional reconstruction methods *Highlights (for review) Title: Discrete X-ray tomographic reconstruction for fast mineral liberation spectrum retrieval.
as part of a metallurgical investigation to identify factors which may promote undesirable recove... more as part of a metallurgical investigation to identify factors which may promote undesirable recovery of uranium in a copper concentrator in Australasia, detailed mineralogical analysis was performed on several drill core samples to identify the uranium bearing phases and other problematic species that could interfere with the flotation of copper sulphides. This was undertaken in parallel with laboratory flotation tests of the drill core samples to investigate the relative flotation behaviour of uranium bearing minerals. QEM-SCAN analysis was conducted on the flotation concentrate to establish the forms in which U was recovered. The study found that uraninite (UO 2 ) and masuyite (Pb[(UO 2 ) 3 O 3 (OH) 2 ]•3H 2 O) were the major U-bearing minerals, extremely fine grained (average grain size 4µm) and apparently associated with copper sulphides and pyrite. The flotation recovery of uranium minerals was moderate (less than 12% in all samples) but above the expected entrainment levels. This can be ascribed to the intrinsic association with copper bearing sulphides (poor liberation). No naturally hydrophobic minerals such as talc, kerogen, etc were identified in the ore mineralogy to trigger any other flotation mechanisms of uranium.
The present work investigates the mineralogical and chemical characteristics of a refractory gold... more The present work investigates the mineralogical and chemical characteristics of a refractory gold (Au) ore (Eburnean Tectonic Province, Ghana) which sometimes display poor carbon-in-leach (CIL) Au extraction behaviour. Currently, the plant feed ores to the leach circuit is prepared by flotation concentrate treatment involving biological oxidation (BIOX®), followed by BIOX® product wash. To understand and diagnose the cause(s) of low Au recovery, detailed mineralogical (QXRD), optical, shape, size and phase discrimination (OM, laser diffraction and SEM), and bulk (XRF/laser ablation-MS, ICP-OES) and surface (EDTA) chemical characterisation of run-of-mine (ROM), flotation concentrate (FC), pre-wash BIOX® product (BIOX® U), low Au recovery post-wash (BIOX® L), and high Au recovery post-wash (BIOX® H) products were investigated. The results show that, the ore is complex sulphidic and comprises quartz (45%), chlorite group, plagioclase feldspar, dolomite, mica group, olivine group, pyrite, siderite, and rutile as major and minor minerals. Chemical analyses showed Au enrichment in sulphides (arsenopyrite, pyrite). Poor Au leach recovery from BIOX® L could be ascribed to cyanicides (chalcopyrite, pyrite, etc.) and passivation (jarosite, beudantite, etc.).
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Papers by Massimiliano Zanin