Navegando por Assunto "Bauxite"

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Acesso aberto (Open Access)
Absorção do dióxido de carbono por resíduo de bauxita em torres de absorção
(Universidade Federal do Pará, 2013-03-04) BOTELHO, Fernando Aracati; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
One of the most discussed environmental problems on the world scene today is global warming and its implications. Although the greenhouse effect is a natural phenomenon, the increase in emissions of gases such as CO2 from the combustion process may favor its aggravation. Following this line, there is interest in conducting research to minimize the release of this gas in the atmosphere. This work aims to study the process of absorption of carbon dioxide by aqueous phase of bauxite residue (soda and dissolved ions in solution) in spray tower and tower saddles random (both pilot scale), as well as check the pH change in this absorption process to both towers. Evaluate pH change and CO2 absorption capacity by considering the following variables: the type of absorption tower, using the supernatant as the absorbent means and the use of the suspension heated by resistances. The results showed that the suspension of bauxite residue absorbed significant amount of CO2, both the spray tower as the tower saddles. The average absorption rate was around 8.42% for the spray tower and 9.34% for the tower saddles. The ability carbonating the suspension of 27%-p was about 33.3 kg CO2 per tonne of waste and there was a substantial reduction of the alkalinity of the residue by reaction with gaseous effluents with a mean decrease of 4.0 and 3.5 pH units for the tower saddles and sprinkler respectively.
Acesso aberto (Open Access)
Controle de qualidade de bauxitas gibbsíticas: predição dos parâmetros AvAl2O3 e RxSiO2 a partir de dados difratométricos por reflexão e transmissão utilizando estatística multivariada
(Universidade Federal do Pará, 2021-02-16) MELO, Caio César Amorim de; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817; https://orcid.org/0000-0002-5880-7638
Currently, traditional wet chemistry methods are used for quality control of bauxites. Such methods indirectly quantify the gibbsite and kaolinite content as available alumina (AvAl2O3) and reactive silica (RxSiO2), respectively, and they are very costly and time-consuming. In order to achieve a rapid and reliable method to estimate these parameters, as alternative to current wet chemistry methods, in this work it is evaluated the use of multivariate statistics – Partial Least Square Regression (PLSR) on XRD data of Brazilian bauxites. The X-ray diffractograms were collected in the reflection and transmission modes, and the data collected by each of these treatments were compared with respect to the quality of the PLSR models. The method was optimized through Principal Component Analysis (PCA) and Factorial Design of Experiments (DOE), from which it was possible to identify outliers, grouping samples with mineralogical similarities into three clusters (C1, C2 and C3), and obtain optimized parameters for the collection and pre-treatment of diffractograms. The best results were obtained using the reflection mode, reducing the 2θ range to 13º – 34º 2θ, increasing the step size from 0.026º to 0.065º, and using standardized data. These collection conditions, although not ideal for most XRD applications, provided both a better accuracy of the predictive models of AvAl2O3 and RxSiO2 and a reduction in the collection time (~ 40 seconds). The results showed that the precision obtained was within the industrially acceptable limits for the quality control of gibbisitic bauxites (AvAl2O3 = 0.49% and 0.83%, and RxSiO2 = 0.32% and 0.23%, respectively for samples of the groups C1 and C2). The prediction was not satisfactory only for marginal bauxites samples (grouped mainly in C3). XRD by transmission allowed the elimination of the preferential orientation effect, however, the accuracy of the model was acceptable only for C1 samples. Compared to the traditional wet chemistry, the proposed method is significantly faster, easier to implement and perform the analyzes, requires less space and manpower, besides no chemical reagents are needed. In addition, with the implementation of X-ray diffraction in the laboratory of the bauxite and alumina industry, it is possible to follow the mineralogy of the ore that feeds the Bayer process and, therefore, to be aware of how variations in the mineralogical composition can impact the process. It is worth noting that such information is still unknown, controlling only the chemical parameters.
Acesso aberto (Open Access)
Desenvolvimento de uma estrutura sanduíche de base polimérica, produzida com resíduos das indústrias de mineração e metalurgia, para aplicação como painel divisório de ambientes internos na construção civil
(Universidade Federal do Pará, 2016-07-05) MIRANDA, Rossana Martins; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The rechearch proposed to use solid wastes from kaolin and bauxite mining and metallurgical regional industries in a composite of sandwich structure to apply as internal divider panel environments. The blade was of unsaturated polyester matrix, double jute fabric and, kaolin waste (20 wt% polyester) and, the core, of polyurethane expansive and red mud (bauxite waste at process to get alumina), from 0 to 50 wt% PU (increasing by 10 to 10 wt%), in a total of 6 different treatments). The tests carried out were: blade density (ASTM C271/271M – 11), sandwich structure bulk density apparent, sandwich structure porosity, tensile test on the blade (ASTM D5083-10), flatwise tensile test on sandwich structure (ASTM C297/C297M - 04), edgewise compressive test on sandwich structure (ASTM C364/C364M–07), flatwise compressive test on sandwich structure (ASTM C297/C297M - 04), 3-point flexural test on sandwich structure (ASTM D7250/D7250M – 06 e ASTM C393/C393M – 11), Charpy impact test on sandwich structure (ASTM D6110 – 10), flammability test on blade and on sandwich structure (UL 94 - 96) and sound transmission loss test on sandwich structure (ISO 140-3:1995 - E). The results indicated that the choise of polymeric matrices was suitable to reduce weight of such structure mainly the use of a PU expansive. Increasing red mud not contributed to significant increase of sandwich structure bulk density apparent. Kaolin waste reinforcement increased resistance to blade on tensile test. Red mud reinforcement reduced sandwich structure resistance on flatwise tensile, flexural and impact tests. Increasing of red mud didn’t influenced sandwich structure edgewise compressive and flatwise compressive tests but, but it´s use at this sandwich structure, decreased their resistance at the first test and increased at the second test. The PU high flammability was delayed for being cloistered by two blades of polyester and kaolin, proving flame retardant property of kaolin waste. And about sound transmission loss test, the increase of red mud increased that until 20% concentration, after this, stabilized at 25 dB (STC) until 50% red mud. The composite, as a whole, presented feature of a sandwich structure, with a low density core, contributing to reduce structure weight and with higher resistant blades, providing it the desired structural feature to be a divider indoor panel.
Acesso aberto (Open Access)
Estudo da influência da granulometria no comportamento reológico de polpa de bauxita e no fator de atrito
(Universidade Federal do Pará, 2011-09-14) BRUM, Sebastião Martins; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
This paper presents studies of the rheological characterization and determination of friction factors in three bauxite slurries originating in Miltonia Mine, Paragominas - Para, resulting from operating conditions with different degrees of grinding. Thus, the basic difference between them lies in the size distribution. The goal is to make a proposal to revise the specification of the product particle size (for the bauxite slurry pipeline), allowing a comparison with the slurries of the project (pilot plant) and the current operation (processing plant) and the response to changes, especially, viscosity and friction factors. The slurry proposal incorporates a higher percentage of fines (<10 microns) compared with other slurries. The benefits can earn recovery with the incorporation of this portion of fines, which currently is discarded to the tailings pond. The material was characterized by size analysis of the series Tyler, physical and physical-chemical, electron microscopy (SEM) and X-ray spectrometry energy dispersive (EDS). Testes were conducted in coaxial cylinder viscometer, Searle type, in order to determine the rheological behavior of these slurries, depending on the size distribution and varying the concentration of solids. The rheological properties were measured viscosity, yield stress and also behaviors that show the dependence of viscosity with the time of application of a constant shear rate, verifying through the hysteresis curve, the presence or absence of thixotropy and reopexia. The experimental results showed that for the slurries tested, the particle size and solids concentration are important parameters in determining the viscosity. Tests with these three bauxite slurries of different sizes, were performed at predetermined concentrations, to determine the model whose rheological parameters showed the best correlation coefficients (R2), and the best fits were found using the Herschel-Bulkley model. The friction factors were obtained for formulations involving a logarithmic relationship, using the Law of the Wall as a method of obtaining these expressions apply to non-Newtonian viscoplastic fluid, and compared with those calculated by Dodge and Metzner correlation and found that in general there is agreement between the model studied in the three slurries. The factor analysis of friction in the concentration of 50% solids, which is the concentration of pumping by pipeline, shows that the behavior of the slurries studied is similar, with the best settings for the range from 10,000 to 100,000 Reynolds (average work range for the turbulent flow of the ore pulp, homogeneous and heterogeneous).
Acesso aberto (Open Access)
Influência da granulometria nas propriedades reológicas da polpa de bauxita pós beneficiamento
(Universidade Federal do Pará, 2015-11-13) REIS, Izabela de Nazaré Souza da Fonseca; FELIPE, Augusta Maria Paulain Ferreira; http://lattes.cnpq.br/8871741271063047; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The knowledge of factors that influence the rheology of bauxite pulp is necessary and important for the quality control of the flow through the pipeline process.This work evaluated the effect of different granulometric fractions (-100#+150#; -150#+200#; -200#+270#; -270#+325# and -400#) on rheology of bauxite pulp that is carried through Mineração Paragominas S/A (MPSA) pipelines. Distinct fractions of bauxite obtained by wet screening were analyzed by an X-Ray Diffractometer (XRD) to determine the mineralogical composition of the samples. The results of those analysis revealed that each fraction has a similar composition (gibsite, kaolinite, hematite, goethit and anatase) though different proportion in the fractions. The studies of rheological parameters were developed by using Thermo Scientific HAAKE Viscotester 550 and the SV1 coaxial cylinder sensor at 30ºC. Bauxite pulps, with constant solids content and equal to 50 wt% were prepared in order to simulate the actual conditions of flow through the pipeline. Testing of apparent viscosity curves versus additive concentration were carried out using sodium polyacrylate at concentrations that ranged from 0 – 1 wt% in order to determine the optimal concentration of additive necessary to stabilize the bauxite pulp. From the results found of optimal concentration of sodium polyacrylate, the hysteresis tests were performed. It was found that the smaller the average particle diameter, the greater the amount of additive is necessary to stabilize the pulp and the addition of sodium polyacrylate in the finer fraction of bauxite caused the flocculation of system. In general, the rheological behavior of the bauxite pulps with their optimal concentrations of sodium polyacrylate was shown to be non-Newtonian and time dependent, with rheopetic behavior for fractions with granulometry between 127 and 48.5 micrometers and thixotropic behavior to fine fraction with average diameter smaller than 37 micrometers. The bauxite pulp formulated with the fine particle size and without addition of sodium polyacrylate showed rheopetic behavior. It was observed, for the dispersed bauxite pulps, that the decrease the average particle size influences the size of the hysteresis area formed, causing a decrease in rheopetic behavior.
Acesso aberto (Open Access)
Mineralogia e geoquímica de bauxitas de Barro Alto (Goiás): considerações genéticas
(Universidade Federal do Pará, 2019-10-01) MOURA, Vitor Hugo Santana; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
In the municipality of Barro Alto, Goiás, a bauxite deposit was developed, mostly, on Neoproterozoic anorthosites. According to recent published data, the general mode of occurrence reinforces the lateritic origin, since bauxite follows the current topographic surface. However, the succession of the horizons is not corresponding to the others of the lateritic model, at least partially. The absence or restricted size of the clay horizon with kaolinite, or the presence of kaolinite bodies sectioning the bauxitic body, which locally reaches large thicknesses, overturn the simple lateritic model. This is reinforced by the absence of the classic leopard skin-like pattern or similar iron-aluminous crust and the absence of other coverage. For various authors the wide occurrence of extensive macrocrystalline, botrioidal gibbsite, apparently occupying venules and fracture walls suggests, along with the diversity of the way of occurrence of clays, a contribution of another process, not only lateritization. From this information a study was elaborated to deepen the knowledge about the formation of the Barro Alto bauxite, detailing the generations of gibbsite and kaolinite, as well as to try to identify the lateritic and hydrothermal contributions with these minerals. In the field, 5 mines explored by the company EDEM - Mineração LTDA were studied (Mining 1, Mining 2, Mining 5, Mining 6 and the SELA trench). From these mines, a greater detail was made in mines 1, 2, 5 and in SELA trench. Forty-eight samples were collected from which 22 most representative samples were selected for laboratory analysis involving mineralogical (X-ray Diffractometry), textural (Optical and Scanning Electron Microscopy), and chemistry (Inductively Coupled Plasma Mass and Optical Emission Spectrometry) characterization. In general, the bauxitic profile of Barro Alto comprises the anorthosite as substrate and possible source rock, on which a porous bauxite horizon (HBP) with stockworks and flint-type veins of kaolin (CF), and locally with subcentimeter corundum crystals (HBPC) was established. They converge to a bauxitic clay zone (ZAB) and then to a massive bauxite horizon (HBM). This in turn is superimposed by a capping formed by centimetric to decametric blocks and nodules of massive bauxite (HBANB), whose occurrence suggests a colluvial formation. In the profiles the horizons HBP, HBPC, HBM and HBANB consist essentially of gibbsite and kaolinite, sometimes containing accessory minerals such as corundum (HBPC), followed by hematite and goethite. In CF and in the bauxite clay zone (ZAB) the dominant mineral is kaolinite and/or halloysite, followed by gibbsite. The chemical composition of the bauxitic profile is basically composed of Al2O3, SiO2 and Fe2O3. CaO, MgO, K2O, MnO, Na2O and P2O5 concentrations are very low (generally <0.09), even below the analytical detection limit. TiO2 contents are also relatively low, generally <0.2%. Trace element concentrations when compared to the average values of the Earth's Upper Crust (EUC) are generally very low. The concentrations of elements such as Cr, Co, Cu, Zn, Rb, Sr, Y, Zr, Nb, Cs, Ba, Hf, Pb, Th and U are below EUC in all horizons. Only the element Mo has more concentrated values in all horizons. On the other hand, V, Ni, Cu, Cr, Ga, and Pb may eventually have higher values especially in some parts of CF and ZAB. Rare Earth Element (REE) concentrations are below the crustal average in all samples studied and also in the anorthosite. The higher concentrations are typically related to the clayey units such as CF and ZAB, and also to the presence of Fe oxides-hydroxides (HBPC). When normalized to the chondrites, the curves exhibit a slightly similar distribution pattern except for porous bauxite with corundum. There is a slight LREE enrichment and a HREE tendency, but only from Tm to Lu. This behavior resembles that of anorthosite, but with much lower concentrations, except for Tm. It is clear the negative anomalies in Ce and positive in Tm, anomalies linked to LREE depletion and a slight enrichment of HREE. From these mineralogical and chemical data, it was possible to distinguish three distinct generations of gibbsite and kaolinite: Gibbsite (I): of the porous bauxitic horizon, which appears to be that formed directly from the plagioclase and almandine; Gibbsite (II): associated with flint kaolin, along with kaolinite, halloysite and even locally hematite; Gibbsita (III): Cohesive and macrocrystalline, sometimes drusic and overlapping the thinner and more compact botryoidal gibbsite. It forms isolated bodies, apparently disconnected from the larger set of bauxites, in pockets of tens of meters wide and depths greater than 40 m; Kaolinite (I) at the gibbsite - anorthosite interface. This kaolinite makes up the halos of anorthosite alteration, when it does not go straight to gibbsite; Kaolinite (II) corresponds to that of flint kaolin, associated with halloysite and sometimes gibbsite. It occurs in the form of venules, veins and pockets, and vertical fractured zones, the stockworks in general. Kaolinite (III) corresponds to that found mainly in the clayey bauxite horizon with nodules, in which this mineral is yellowish, earthy, invading the bauxite mass and involves the centimetric to decametric nodules. The generations of gibbsite, I, II and III, especially II and III, are not compatible with lateritic evolution, likewise the kaolinite, I, II, and III generations, where I and II are not clearly lateritic, and the III seems to be current pedogenetic. Therefore, it is likely that Barro Alto bauxites are the product of the intense subsurface hydrothermal activity of anorthosites, due to the strong structural deformation in which these rocks were subjected in their final post-emplacement stages.
Acesso aberto (Open Access)
Mineralogia e Geoquímica de U, Th, ETR e outros elementos-traço em bauxitas da região de Paragominas, NE do Pará
(Universidade Federal do Pará, 2022-08-17) PARAENSE, Breno Marcelo Ribeiro; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
The state of Pará has the largest deposits of metallurgical bauxite in Brazil, with emphasis on the western regions (municipalities of Oriximiná and Juruti, with two mines in operation) and Northeast regions of the state (municipalities of Paragominas – one mine in operation – and Rondon do Pará). The lateritic/bauxitic cover of the bauxite province of Paragominas is a product of extreme weathering of siliciclastic sedimentary rocks and is composed of minerals resulting from the highest degree of alteration, that is, kaolinite (Al2Si2O5 (OH)4), gibbsite (Al(OH) )3 , goethite (FeOOH), hematite (Fe2O3) and anatase (TiO2), to which are added traces of relict quartz, traces of heavily degraded mica and heavy minerals of greater resistance in humid tropical conditions such as rutile (TiO2), tourmaline and zircon (ZrSiO4). In addition to the extraction of bauxite, its mineral transformation, which takes place in the industrial district of Barcarena, near Belém, with the Hydro-Alunorte Alumina refinery, and the production of metallic aluminum by Albras. Due to recent events related to the disposal of waste in decantation basins (DRS) used by the mining company, a climate of distrust on the part of public opinion regarding the safety of the mining populations that live in the vicinity of the company, especially regarding the issue of human health, since the constitution of residues from the mineral transformation of the ore is not completely known. The objective of this research is to determine the presence and study the geochemical behavior of trace elements such as U, Th and ETR, in addition to other heavy metals, such as Hg, Cd and Pb, in bauxites and lateritic covers from the Miltônia mine, in Paragominas, and residues (red muds) from Barcarena, the relationship with the accessory mineralogy of these materials and establishment of reference or background values for environmental assessment. The present work was carried out with samples from 1 bauxite profile (section HIJ-231), located in the Miltônia 3 mine, collected through drilling holes and/or from the mine front, process samples were also collected from the SAG mill of the plant I, separated into different granulometric fractions, supplied by Norsk Hydro. The XRD and XRF analytical processes were carried out at the Mineral Characterization Laboratory (LCM) from UFPA, while the Scanning Electronic Microscopy stage was carried out at the Microanalysis Laboratory of same Unit/Institution. The results of chemical and mineralogical analyzes of samples from the Miltônia 3 mine, both raw bauxite and its granulometric fractions, after autogenous milling, showed a relationship between the high values of ZrO2 and TiO2 verified and the accessory minerals - zircon, rutile and anatase.
Acesso aberto (Open Access)
Mineralogia e geoquímica do perfil laterito bauxítico na serra Sul, Província Mineral de Carajás
(Universidade Federal do Pará, 2020-11-03) RODRIGUES, Paulo Ronny Soares; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The Amazon holds the largest reserves of bauxites in Brazil, located in Trombetas, Juruti, Paragominas and Rondon do Pará. The Carajás region, with large lateritic deposits, especially of iron, is also emerging with potential for bauxite deposits, with emphasis on those of Serra Norte. In Serras Sul, smaller occurrences were identified, which were investigated in this work. In this context, field activities were carried out with sample collection and textural, mineralogical and chemical analyzes and then a genetic discussion was presented. In four alteration profiles on a side road near the Serra Sul, after geological cartography, 23 samples were collected, which were described, photographed and prepared for mineralogical analysis (X-ray diffraction), textural (optical and scanning electron microscopy) and chemical (mass and optical emission spectrometry, with inductively coupled plasma). The bauxite laterite profile comprises from the base to the top of: 1) Kaolin Horizon (HC); 2) Mottled clay Horizon (HAM); 3) Nodular Bauxite Horizon (HBN); 4) Clayey Bauxite Horizon (HBA) and 5) Ferruginous crust Horizon (HF); and finally to the top 6) Dismantled crust ferruginous horizon (HFD. The chemical composition is essentially dominated by Al2O3, Fe2O3, SiO2 and TiO2, which compose the main minerals, kaolinite, gibbsite, hematite, goethite and anatase. The trace elements V, Cr, Cu, Ga, As, Zr, Cd, Hf, Bi and Th, whose concentrations are generally higher than those of the Upper Crust of the Earth, are more concentrated in the ferruginous horizons, related to Fe oxy-hydroxides (hematite and goethite) and also to zircon. On the other hand, the elements Co, Zn, Se, Rb, Sr, (Nb), Ag, (Sn), Cs, Ba and Pb are at lower levels than theUpper Continental Crust, and their concentrations are lower in ferruginous horizons, suggesting affinity with clay minerals.ETR at levels lower than UCC, are enriched in ETRP and present strong positive and negative C and positive Eu anomaly, and suggest distribution in zircon, oxy-hydroxides of Fe and other mineral phases. and mass clearly demonstrate a complete lateritic evolution, only partially modified in its upper portion. The bauxite zone, however, does not have local potential for ore, due to the low content of usable alumina and high in reactive silica. However, its occurrence opens an opportunity for further research in view of the geological and paleoenvironmental potential of the Mineral Province of Carajás.
Acesso aberto (Open Access)
The Belterra Clay On The Bauxite Deposits Of Rondon Do Pará, Eastern Amazon
(Sociedade Brasileira de Geologia, 2018-09) NEGRÃO, Leonardo Boiadeiro Ayres; COSTA, Marcondes Lima da; POELLMANN, Herbert
Bauxite deposits in the Amazon region are commonly covered by yellowish clays which can reach up to 25m thick, known as Belterra Clay (BTC). In Rondon do Pará, Eastern Amazon, BTC is 13m thick and covers world-class bauxite reserves. Three pilot bauxite mines were investigated in Rondon do Pará for an initial characterization of the local BTC. In discordant contact with the lateritic profile, the BTC has reddish brown colors at its base to ocher tones towards the top. It has a massive structure with silt-clayey texture and nodular bauxitic fragments at its base. Rietveld mineral quantification of the material attests that it is dominated by kaolinite, with goethite, gibbsite, hematite, anatase and residual quartz. The thermal behavior of the material also confirms its mineralogical composition. Kaolinite is of low structural order, which was considered the main difficulty in the application of the Rietveld method. Goethite has up to 33 mol% of Al. As observed by scanning electron microscopy (SEM), the minerals represent pseudo-hexagonal crystals measuring from 150 to 700 nm. The BTC in the studied area is correlated to BTC on others bauxitic deposits of the Amazon region, suggesting this material experienced the same genesis and geological evolution, probably during the Pliocene.