Center for Mineral Technology

Miguel Calmon, Brazil

Center for Mineral Technology

Miguel Calmon, Brazil

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Bertolino L.C.,Center for Mineral Technology | Rossi A.M.,Brazilian Center for Research in Physics (CBPF) | Scorzelli R.B.,Brazilian Center for Research in Physics (CBPF) | Torem M.L.,Pontifical Catholic University of Rio de Janeiro
Applied Clay Science | Year: 2010

Well characterized kaolin samples from different deposits of Brazil were studied by electron paramagnetic resonance. Three paramagnetic species attributed to iron in different chemical environments were identified in raw samples. A very intense and broad line with 0.2mT linewidth was typical of large particles of iron oxides/hydroxides. A species at g=2.0 with 0.04mT line width was associated with superparamagnetic particles adsorbed to kaolinite surfaces or trapped between its lamellae. An isotropic and/or orthorhombic species in the g=4.2 region belongs to structural Fe 3+ replacing Al 3+ in sites with different crystal-field symmetries. It was verified that large iron oxide particles were responsible for keeping the kaolin whiteness at levels below 50%. Superparamagnetic iron particles mainly affect whiteness in the range of 50%< whiteness <86%. They may be totally removed by magnetic separation followed by chemical treatment using sodium dithionite. The kaolin high whiteness levels (whiteness >86%) were determined by Fe 3+ iron content in the kaolinite structure. However, only a small part of this species can be removed from the kaolinite structure by traditional industrial processing techniques. These results showed that EPR is a powerful technique to assist in controlling kaolin quality in industrial processes. © 2010 Elsevier B.V.


Neumann R.,Center for Mineral Technology | Avelar A.N.,Vale SA | Da Costa G.M.,Federal University of Ouro Preto
Minerals Engineering | Year: 2014

Although bauxites usually have a quite simple mineralogy - gibbsite (+boehmite), quartz, kaolinite, hematite, goethite, anatase (+rutile) and minor or less common phases, fine particle size, low crystallinity and variable compositions of the iron minerals might render phase quantification difficult, as well as impairing bauxite processing. A reliable and complete characterisation is therefore necessary in order to predict processing performance and ensure compliance to plant specifications. X-ray diffraction is the most important single tool for bauxite characterisation, and the constrained refinement of the Al-for-Fe substitution in goethite during one-step phase quantification by fundamental parameters Rietveld method has been successfully used. The same method was developed to analyse the coupled Al-for-Fe and OH --for-O2- substitutions in hematite. The method was tested against Mössbauer spectroscopy iron distribution on bauxite samples with a large compositional range, and on bauxite Certified Reference Materials from the main Brazilian mines, with improved results and widened range of conclusions that can be drawn related to bauxite processing. © 2013 Elsevier Ltd. All rights reserved.


Neumann R.,Center for Mineral Technology | Medeiros E.B.,MBAC Fertilizer Corporation
International Journal of Mineral Processing | Year: 2015

The rare earth elements (REE) are essential for a wide range of applications, from strategic assets (e.g. petroleum cracking, magnets for wind turbines) to popular merchandise, as smartphones. Since 2010, when China, the worlds close to exclusive REE supplier, imposed export quotas, several old and new deposits have been evaluated to compensate market shortage, taking advantage of significant price rises. The Araxá rare earth elements prospect boast a large reserve (6.34 Mt @ 5.01% REO), as well as phosphate and niobium, in a deeply weathered ore of carbonatitic origin. The mineralogy and the ore properties are unconventional for rare earth elements, and require a detailed mineralogical and technological characterisation as starting point to develop a feasible processing route. Rare earths are predominantly carried by monazite (over 70%), and by a solid solution of the plumbogummite group minerals where the barium-rich term gorceixite predominates, while cerianite and bastnaesite account for less than 1% each. Minerals of the pyrochlore supergroup are the main Nb carriers, but phosphate is also due to monazite and the plumbogummite group minerals, as apatite has barely been detected. Goethite, high-Al hematite and quartz are the main gangue minerals, and goethite is thoroughly intergrown with the other phases. Fine particle size (P50 close to 45 μm) and 47.4% of the REE in the - 20 μm size fraction is another feature typical of this kind of ore. The mineralogical and textural complexity of the ore required a comprehensive technological characterisation in order to evaluate processing options. Based on textural measurements, the concentration of monazite, the concentration of the REE carrying minerals and the reverse removal of quartz, as processing option for this ore, have been simulated. Incomplete liberation of monazite does limit its grade in an ideal concentrate to 80%, and its recovery to 70%. The low monazite recovery must be added to the loss of REE carried by other phases, reducing the overall REE recovery to below 45%. Monazite has also a very limited exposition of the mineral on the particle's surfaces, supposed to impair process efficiency enough to keep experimental results significantly far from the simulated ones. The concentration of the REE-bearing minerals might be efficient from the liberation point of view, and over 90% of the REE carriers can be recovered to a 97% grade concentrate. Due to the low REE grade of predominant gorceixite (3.3%), however, the concentrate's grade of 14% REE is just slightly above the double of the ore's grade. For the REE-bearing minerals taken together, the process efficiency might be hampered by selectivity due to the complex mineralogy. The major gangue minerals, goethite and hematite, are strongly intergrown with the other minerals of the assemblage, to an extent that evaluating reverse processing considering these phases was not feasible. The removal of quartz by reverse processing is quite straightforward, and 95% of the mineral might be removed to a high-grade quartz concentrate of 93%, with loss of REE of only 0.14%. The mass discharge of 8.7%, however, rises the grade of the concentrate only to 7.3% REE. Complex mineralogy and the fine crystals and particles with strong intergrowth that characterise the ore hamper efficient concentration for the Araxá REE ore, and direct hydrometallurgical processing of the whole was adopted. The results are in agreement with the few other published attempts to concentrate the rare earth minerals from residual lateritic ores related to carbonatites. © 2015 Elsevier B.V. All rights reserved.


Santos S.F.,Federal University of Rio de Janeiro | Franca S.C.A.,Center for Mineral Technology | Ogasawara T.,Center for Mineral Technology
Mining Science and Technology | Year: 2011

A method of dry grinding muscovite based on the use of knife-mills is reported. It was possible to produce mica with a particle size below 100 and 45 μm. After grinding, the samples were submitted to sonication treatment, which promoted delamination of the material. The particle size distribution shows that sonicated mica has more particles in the size range 10-50 μm than does non-sonicated mica have. This also indicates a decrease in the average particle size. Characterization of the treated muscovite by scanning electron microscopy revealed a highly delaminated material with a plate-like structure. The products were characterized by chemical analysis and X-ray diffraction, too. This mica has already been used for the synthesis of pearlescent pigments. © 2011, China University of Mining & Technology. All rights reserved.


Brum M.C.,Federal University of Rio de Janeiro | Capitaneo J.L.,Federal University of Rio de Janeiro | Oliveira J.F.,Federal University of Rio de Janeiro | Oliveira J.F.,Center for Mineral Technology
Minerals Engineering | Year: 2010

The utilization of organoclays as adsorbents in the remediation of polluted water has been the subject of many recent research studies. In the present work, the adsorption of hexavalent chromium onto montmorillonite modified by the cationic surfactant cetylpyridinium bromide (CPB) was studied by aiming at water pollution remediation. The electrophoretic mobility measurements of the organo-montmorillonite showed a zeta potential reversion from negative to positive in the whole acidic pH range and up to pH 8.5. In some cases the adsorption of chromate ions onto the organo-montmorillonite was higher than 98% and was well described by the Langmuir adsorption isotherm. The utilization of montmorillonite modified by CPB showed to be an attractive solution to the remediation of water contaminated with chromate ions. © 2009 Elsevier Ltd. All rights reserved.


Rambo D.A.S.,Federal University of Rio de Janeiro | de Andrade Silva F.,Pontifical Catholic University of Rio de Janeiro | Toledo Filho R.D.,Federal University of Rio de Janeiro | da Fonseca Martins Gomes O.,Center for Mineral Technology
Materials and Design | Year: 2015

The work in hand presents the results of an experimental investigation on the thermo-mechanical properties of a textile refractory composite reinforced with polymer coated basalt fibers under tensile loading. The composites were produced as a laminate material using basalt bi-directional fabric layers as reinforcement. A high alumina cement matrix was used in the matrix composition which was designed using the compressible packing method. A series of uniaxial tensile tests was performed under temperatures ranging from 25 to 1000. °C. The cracking mechanisms were discussed and compared to that obtained at room temperature. Thermogravimetry and X-ray diffraction analysis were used to study the deterioration/phase changes as a function of the studied temperatures. Scanning electron microscopy (SEM) was used to study the damage processes in the fiber-matrix interfaces after exposure to high temperatures. The obtained results indicated that the presence and the type of coating can become a deterministic factor in the tensile response of the composite submitted to elevated temperatures. A sudden drop in the serviceability limit state of the composite was observed above 400. °C, caused by the degradation of the polymer used as a fiber surface coating, the degradation of the basalt fiber and by the dehydration process of the refractory matrix. © 2014 Elsevier Ltd.


Merma A.G.,Pontifical Catholic University of Rio de Janeiro | Torem M.L.,Pontifical Catholic University of Rio de Janeiro | Moran J.J.V.,Pontifical Catholic University of Rio de Janeiro | Monte M.B.M.,Center for Mineral Technology
Minerals Engineering | Year: 2013

Mineral bioflotation encompasses the principles and methods used in mineral flotation using microorganisms as flotation reagents. This work deals with the fundamental aspects of apatite and quartz flotation using Rhodococcus opacus bacteria as a bioreagent. Each mineral sample was conditioning with the bacterial suspension in a rotary shaker under specific conditions as particle size, biomass concentration, pH solution and conditioning time, for all the studies done during the research. The zeta potential results showed a change in zeta potential measurements of the minerals after the bacterial interaction. This change was more significant in the zeta potential curves of apatite than those for quartz. The results also suggest that the bacterial adhesion onto the mineral surfaces was predominantly specific. The greatest apatite flotability achieved 90% at pH around 5, in the presence of 150 mg L-1 of bacteria after 5 min of flotation. On the other hand, quartz achieved a flotability of 14% under identical experimental conditions. The fundamental flotation studies revealed the prospect that R. opacus presents as a biocollector and biofrother and indicate its promising application in phosphate flotation industry. © 2012 Elsevier Ltd. All rights reserved.


Veneu D.M.,Center for Mineral Technology | Torem M.L.,Pontifical Catholic University of Rio de Janeiro | Pino G.A.H.,Pontifical Catholic University of Rio de Janeiro
Minerals Engineering | Year: 2013

The first line of biosorption technology research aims to enhance pathways for the use of novel biosorbents, and thus, reduce the utilization of noneco-friendly process based in chemical products, and to provide economic and sustainable alternatives to conventional process. This subject presents a multidisciplinary approach and requires the fundamentals of water chemistry, biochemistry and surface chemistry to name a few. Biological processes have been attracting attention in heavy metals removal by bacterial strains, due to lower operating costs and their potential applications for ionic metal species removal from aqueous solutions even in high concentrations. The ability of Streptomyces lunalinharesii to sorb copper and zinc from aqueous solutions was investigated through batch experiments at 25 °C. Various sorption parameters such as contact time, initial metal concentration, pH and biomass concentration and the sorption capacity were studied. The degree of copper and zinc removal achieved values around 81% and 60% at pH 5.0 and 6.0, respectively. Moreover, the metals uptake remained constant for contact time above 30 min. The experimental data at equilibrium were fitted to Langmuir and Freundlich adsorption isotherm models and the model parameters were evaluated. The kinetic study showed that the pseudo-second-order rate equation better described the biosorption process. The FTIR analysis revealed that hydroxyl, carboxyl and amine groups were major binding groups. © 2012 Elsevier Ltd. All rights reserved.


Veneu D.M.,Center for Mineral Technology | Pino G.A.H.,Pontifical Catholic University of Rio de Janeiro | Torem M.L.,Pontifical Catholic University of Rio de Janeiro | Saint'Pierre T.D.,Pontifical Catholic University of Rio de Janeiro
Minerals Engineering | Year: 2012

The aim of this work was to study the fundamental aspects of a combined biosorption/bioflotation system applied to cadmium removal from aqueous solutions using a Streptomyces lunalinharesii strain. The main sorption conditions, such as solution pH, biomass concentration and the initial concentration of cadmium were evaluated on the metal uptake performance. The characterization of the biosorbent was carried out through zeta potential measurements, FTIR spectra and SEM images. From the sorption studies, it was observed that the metal removal was significant, around 55% in a single stage, and took place at pH around 5.0; biosorption studies showed that the Langmuir model fitted properly well. Moreover, the maximum cadmium uptake was about 24.8 mg g -1. The kinetic works showed that the pseudo-second-order model appropriately fitted the experimental data. The integrated process of biosorption-bioflotation achieved a cadmium removal value around 61%. © 2011 Elsevier Ltd. All rights reserved.


Castilhos Z.C.,Center for Mineral Technology
One Century of the Discovery of Arsenicosis in Latin America (1914-2014): As 2014 - Proceedings of the 5th International Congress on Arsenic in the Environment | Year: 2014

The objective of this study was to estimate the potential risk on the health of residents of Paracatu (adults and children) due exposure to arsenic present in soil, water, air and food. For the assessed receptors, the risk due to the present contamination scenario was higher than the limit considered acceptable. The main pathways were ingestion of water while swimming and inhalation of particulates. It is important to highlight that human health risk assessment is a very conservative modeling, trying to protect the human health including critical subpopulations. Epidemiological study carried out at Paracatu city will bring new elements to the uncertainties in the human health risk assessment. © 2014 Taylor & Francis Group.

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