Navegando por Assunto "Bauxita"

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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)
Alteração supergênica das rochas básicas do grupo Grão-Pará: implicações sobre a gênese do depósito de bauxita de N5 - Serra dos Carajás
(Universidade Federal do Pará, 1981-11-19) LEMOS, Vanda Porpino; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983
The present study deals with the supergene alteration of the basic volcanic rocks of the Grão Pará Group and gathers evidences that support the N5 bauxite deposit (Carajás Sierra) to be an extreme product of this alteration. In the lack of a continuous profile, this hypothesis was tested with a composed profile using the subsurface information available for the contiguous N4 plateau where the whole weathered sequence could be observed. The bauxite-rich and lateritic horizons, only developed in N5, were then assumed to be a part of that sequence and taken as its more superficial levels. The basic volcanic rocks are of precambrian age and were classified as tholeiitic basalts compositionally similar to those of the calc-alkaline suites that occur in modern island ares (TiO2-Zr/P2O5 diagram). The primary mineral assembly is dominantly composed of labradorite and pigeonite-augite and has zircon, ilmenite and opaque minerals as the major accessory phases. Hydrothermal activity caused mineralogical changes in theses rocks producing chlorite, epidote, calcite, sericite, amphibole and quartz. Significant chemical and mineralogical changes were induced by the weathering in these rocks and could be evaluated to depths up to 140 m. The serbidecomposed material showed substantial losses of CaO, Na2O and FeO (this due to partial oxidation to Fe+3) and less important lasses of SiO2, MgO and K2O. In contraposition there was relative enrichment of Fe2O3, Al2O3, TiO2 and P2O5 besides major gains of H2O. This new chemical environment favored the formation of compatible stable phases represented, in order of abundance, by chlorite, smectite-chlorite, opaque minerals and quartz. The totally decomposed basalts revealed an aimost complete loss of alkalls, MgO and CaO, with SiO2 contents dimishing to values of approximately 40% of its initial quantities. This enhanced great relative gains of Fe2O3, Al2O3, TiO2 and P2O5 and H2O with respect to the previous alterations stage. The resulting mineral assembly turned out be dominated by kaolinite, goethite and titanium oxides, and secondarily by gibbsite and quartz. Determinations of Cr, Ni, Co and Zr were done for both the bas.alts and its weathered equivalents. Enrichment factors of the order of 1.5 to 5.0 generally progressive towards the surface indicate the greater or lesser mobility of these elements within the supergene environment. Cr, Ni and Co were retained by coprecitpitation with iron hidroxides while Zr was accounted for by the preservation of zircon as a residual mineral. The N5 bauxite deposit consists of a gibbsite-rich upper layer with an average thickness of 4.7 m and average chemical composition of 3-.13% SiO2, 2.3% TiO2, 47.0% Al2O3, 23.0% Fe2O3 and 24.0% volatiles. Mineralogically it is composed of gibbsite, kaolinite, titanium oxides and iron hidroxides (goethite). The subjacent layers show distinct chemical constitution but the mineral suites differ in the proportions rather than in the kinds of the phases present. Downwards it is observed 1) a lateritic crust as thick as 10 m, 2) a gibbsite-rich clay that do not exceed 35 m in thickness and 3) an argillaceous horizon of indefinite thickness. The lateritic crust has an average chemical composition of 3.6% SiO2, 2.0% TiO2, 28.0% Al2O3, 47.0% Fe2O3 and 19.0% volatiles, and a mineralogy dominated by hematite, kaolinite, iron hidroxides, titanium oxides and subordinate quantities of gibbsite. The gibbsite-rich clay has average proportions of 24.0%, 2.0%, 28.0%, 32.0% and 13.0.% for SiO2, TiO2, Al2O3, Fe2O3 and volatiles respectively while the argillaceous horizon shows average proportions of 47.0%, 1.5%, 20.0%, 22.0% and 7.5% for these same components in that order. The mineral assembly of these two last levels is dominated by kaolinite, gibbsite, titanium oxides and iron hydroxides although hematite appears only in the gibbsite-rich clay while goethite and quartz appear, only ,in, the argillacebus horizon. The identification of heavy minerals in samples of both the decomposed basalt and the bauxite material revealed the same suite consisting of ilmenite, zircon and tourmaline, the latter mineral being found in greater abundances in the bauxite. Boron determinations from samples of the various horizons of both sequentes (N4 and N5) indicated contente that varied from 70 to 100 ppm, justifying /the probable presence of tourmaline even in the rocks from which was not possible to separate heavy minerals. The integration of all these data allowed the interpretation of the N5 bauxite plateau as a residual deposit of the supergene alteration of the volcanic basic rocks of the Grão Pará. Group with basis on 1) the chemical and mineralogical identities between the two sequences, especially the decomposed basalt and the gibbsite-rich clay, 2) the chemical correspondente that suggests the argillaceous horizon to be an intermediate stage of alteration between the semidecomposed and the decomposed basalt, 3) the presence of gibbsite in the decomposed basalt suggesting a stage of evolution which, given enough time and the appropriate conditions, could produce a material progressively rich in alumina and 4) typical trace elements of basic rocks present in relatively high concentrations in the bauxite deposit and, taken the genetic link for granted, showing enrichment or impoverishment factors along a common trend from the unaltered basalt to the bauxite material. Special attention was paid to the lateritic crust that formed underlying the bauxite deposit. It has been interpreted as a result of the relativo mobility of Fe and Pd, under Eh-pH conditions that favored the descending movement of Fe and the fixation of in the upper horizons.
Acesso aberto (Open Access)
Análise mineralógica por difratometria de raios-X e método de análise de agrupamento (cluster analysis) como critério para individualização de horizontes bauxíticos
(Universidade Federal do Pará, 2017-03-08) OLIVEIRA, Kelly Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The formation of wide profile of alteration like as bauxitic deposits on Amazon during Cenozoic period is resultant of intense intemperism caused by seasonal climate, elevated temperature and humidity that are characteristics this region. The bauxitic Province of Paragominas, localized in the east portion the state Pará and west portion of Maranhão, occupies 50,000 km2 approximately forming the largest group of bauxite of Brazil. This work was used X-ray diffractometry, a technique that requires little analysis time, minimum pretreatment steps and small sample amounts, associated with cluster analysis for identify and group samples of same horizon of bauxitic profile of the mine Miltonia 3, Paragominas-PA. The results obtain were correlated with chemical analysis, frequently used for quality control and processing of bauxites. The samples used in this work and your chemical analysis were made available for company Norsk Hydro. The mineralogical types of ore were initially defined through clusters analysis of the XRD patterns of two sections (HIJ-229 e HIJ-231) from polling mesh, with 23 holes each section, and with 375 samples analyzed in all. Based on peak position and intensity of the pattern XRD was possible discern the bauxitics horizons. Due the mineralogic similarity this horizon, the differences found in this group refer principals proportions of minerals constituents: Gibbsite, kaolinite, goethite, hematite, and, more rarely, quartz and anatase. Thought clusters analyses was possible to separate by group a set of similar samples, besides facilitate the analysis of many samples quickly and with efficient results. It was possible yet observe a good correlation of the clusters with the lithotypes identified by the company Norsk Hydro through the results of the chemical analysis. In this way, the analysis of clusters in diffractograms of samples of aluminum ore can be an efficient tool aiding in the protocols of processing of this material.
Acesso aberto (Open Access)
Application of bauxite waste from amazon region in the heavy clay industry
(2013-12) HILDEBRANDO, Edemarino Araujo; SOUZA, José Antônio da Silva; ANGÉLICA, Rômulo Simões; NEVES, Roberto de Freitas
In this work, a method was developed for the application of red mud, an alkaline leaching waste, from a bauxite processing plant located in northern Brazil (Amazon region) as starting material for heavy clay products. Samples were prepared by pressing blends of red mud and clay, which were then fired at temperatures from 900 ºC to 1190 ºC. Characterization was carried out by chemical analysis, differential thermal analysis (DTA) and X-ray diffraction (XRD), and the following ceramic properties were evaluated: water absorption, linear shrinkage and flexural strength. In order to evaluate the Na+ stability in the dense ceramic, leaching tests were also carried out on the specimens after sintering process. Results indicated that samples with 50 and 70 wt% of red mud are proper for being used in the production of ceramic bodies, due to its excellent properties, mainly high mechanical resistance and low water absorption, showing thus, an option to minimizing the environmental impacts caused by the aluminum industry.
Acesso aberto (Open Access)
Caracterização química e mineralógica de bauxitas da Amazônia Oriental através de métodos por fluorescência (FRX) e difração (DRX) de raios-X
(Universidade Federal do Pará, 1996-05-26) SANTOS, Antônio Carlos Figueiredo dos; SCHUCKMANN, Walter Klaus
Acesso aberto (Open Access)
Concretes with red mud coarse aggregates
(2012-06) OLIVEIRA, Dênio Ramam Carvalho de; ROSSI, Carlos Rodrigo Costa
Red mud (RM) is a mineral waste, residue of the Bayer process used to obtain alumina from bauxite. While the exploration of rolled pebble damages the environment and is much more controlled by the government, the huge RM disposal areas do not stop increasing and polluting soil, rivers and groundwater sources in Amazon. In this work, the material mixtures used to produce coarse aggregates presented up to 80% of RM, 30% of metakaolin and 30% of active silica as recycled waste. Several tests were carried out to determine the aggregates physical properties and to evaluate the mechanical performance of the concretes with the new aggregates, including hydraulic abrasion strength, and the results were compared to the reference ones, i.e. rolled pebble concretes. Additionally, the sintering process neutralizes any toxic substance as occur in some RM products like tiles and bricks, and these results have encouraged an industrial or semi-industrial production of RM aggregates for concretes.
Acesso aberto (Open Access)
Controle de qualidade de bauxita: otimização do método via úmida para RxSiO2 e método alternativo via WDXRF para AvAl2O3
(Universidade Federal do Pará, 2018-07-09) GOMES, Bruna Serrão; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817
In the metallurgical bauxite industry the quality control of the ore is performed by two chemical parameters, namely: available alumina (AvAl2O3) and reactive silica (RxSiO2), determined according to a procedure that simulates Bayer digestion in laboratory scale. They are parameters for prospective control, mining, processing and ore feeding in the Bayer process. For gibbsite bauxites, which are of interest in this work, AvAl2O3 is associated with the mineral-gibbsite and RxSiO2 to the mineral kaolinite, which is undesired and controlled in the Bayer process because it reacts with NaOH (leaching agent) to form Bayer sodalite, causing irreversible losses of NaOH - which means a considerable increase in the production cost of alumina. Bayer sodalite is a sodium aluminosilicate, insoluble in Bayer digestion conditions and therefore discarded along with the other insoluble bargain minerals in the red mud (insoluble solid residue of the Bayer process). In this context, we sought to: (1) optimize the Alcan method, aiming acid economy by proposing new acid dissolution conditions varying acid type (HCl, H2SO4 and HNO3), acid volume (20, 25 and 30 mL) and (2, 2.28 and 3.8 g), one of the steps for the determination of RxSiO2 and (2) proposing an alternative method for the determination of AvAl2O3 by WDXRF (X-Ray Fluorescence Spectrometry by Length of Dispersive Wave) through mass balance in digestion. Secondary patterns of red mud were properly characterized (XRD, DTA and XRF) and calibrated bauxite and red mud analytical curves with optimal response for linearity and reproducibility. The acid dissolution study of sodalite Bayer showed potential savings in the volume of acid for 25 mL of HCl for ores with up to 45% RxSiO2 and 20 mL for ores with up to 9% of RxSiO2. The HNO3 and H2SO4 presented discrepancies between the contents dissolved in different contents of RxSiO2, whose main influence was the salt used for the effect of the common ion, since NaCl is used in the Alcan method for HCl. Therefore it is necessary to investigate the best salt for dissolution tests with these acids. The mass balance by mineralogical estimation proved more efficient for the future development of the alternative proposal for AvAl2O3 determination studied in this work.
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.
Desconhecido
Difração de raios X em minerais de bauxita e análise através de refinamento pelo método de Rietveld
(Universidade Federal do Pará, 2011) ERDÓCIA, Félix Anderson Barros; REMÉDIOS, Cláudio Márcio Rocha; http://lattes.cnpq.br/7146076994037490
The aluminum metal is obtained from bauxite ore, great industrial importance, consisting of one or more types of aluminum hydroxide plus a mixture of compounds containing silica, iron oxide, titania and aluminosilicates. Because of the variation in the relative concentration of these components in different samples of bauxite, the qualitative and quantitative mineralogy of the ore, has great importance with regard to its technological application, since this is directly related to the content of these components. This work was applied in eight samples of bauxite, extracted from a mine in Paragominas, the process of refining the spectra of X-ray diffraction using the Rietveld method, which were identified and quantified the crystalline phases: gibbsite, kaolinite, goehtita, anatase, quartz and hematite. Carried the refinements of the samples, we found that all had high levels of Gibbsite and Goethite low which gives an excellent type of bauxite to be used in extraction of alumina.
Acesso aberto (Open Access)
Efeito de aditivos no comportamento reológico do rejeito da bauxita
(Universidade Federal do Pará, 2015-03) GONÇALVES, Silvane Gonçalves e; BRUM, Sebastião Martins; FELIPE, Augusta Maria Paulain Ferreira; SOUZA, José Antônio da Silva; FERREIRA, Keylla Castro
In the bauxite mining in Parogominas, PA, Brazil, tailings are discarded in the processing with 33.5% of solids content and small particle size with D50 below 5 µm. These factors contribute to this suspension basically formed by silicoaluminates, with high concentrations of kaolinite clay, increase the viscosity and the yield stress, these factors are important during the pumping. It was performed granulometric analysis and determined the chemical and mineralogical composition of the material. It was studied the use of the sodium hexametaphosphate and polyacrylamide 25% anionic to decrease the viscosity. The result show that the viscosity decrease with use of 23.8 g/ton for the polyacrylamide and 101.75 g/ton for the sodium hexametaphosphate. The particle size and the pH have influence in the behavior of the additives.
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)
Estudo do comportamento térmico e propriedades físico-mecânicas da lama vermelha
(2010) MERCURY, José Manuel Rivas; GALDINO, Laécio Gomes; VASCONCELOS, Nazaré do Socorro Lemos Silva; PAIVA, Antonio Ernandes Macêdo; CABRAL JÚNIOR, Aluísio Alves; ANGÉLICA, Rômulo Simões
The present work studied the thermal behavior, the evolution of the crystalline phases with temperature and the ceramic properties of the red mud (bauxite tailing) from an aluminium industry of the Maranhao state. The research was carried out by Simultaneous Thermal Analysis (TG-DTA), Optical Dilatometry up to 1350 ºC, while the evolution of the crystalline phases was performed by X-ray diffraction analysis upon heating between 750 to 1150 ºC. Physical-mechanical properties, like Specific Surface Area, Particle Size Distribution, Plastic Limit (PL), Liquid Limit (LL), Plasticity Index (PI), Flexural Strength, Water Absorption (WA), Linear Shrinkage After Firing (LS) and the Apparent Porosity (AP) were also determined at the same range of temperature. The following major crystalline phases were detected: hematite, sodalite, and anatase at 750 ≤ T ≤ 850 ºC; and hematite, nepheline and sodalite at 950 ≤ T ≤ 1150 ºC. The technological experiments indicated that red mud can be used for the processing of structural ceramic materials, since it is an inert material between 870-950 ºC and presents highest water absorption and lowest shrinkage and flexural strength. At 950 ≤ T ≤ 1350 ºC, red mud presented a high shrinking of almost 5 to 50 % with total fusion at 1350 ºC, due to the presence of feldspathoids phases in its mineral composition.
Acesso aberto (Open Access)
Estudo geológico das lateritas aluminosas da Serra de Trucarã (Tucuruí, Estado do Pará)
(Universidade Federal do Pará, 1989-05-24) SOUZA, Eliene Lopes de; KOTSCHOUBEY, Basile; http://lattes.cnpq.br/0096549701457340
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)
Investigação do processo de corrosão causado pela polpa de bauxita em mineroduto de aço carbono
(2015-03) SANTOS, Marcelo Costa; PINHEIRO, Clairon Lima; CARDOSO FILHO, José Carlos de Araújo
The corrosion caused by the ore slurry transported plays a fundamental role in the lifetime of a pipeline. Thus, the corrosion of API 5L-X70 carbon steel was investigated using process water and bauxite pulp (5% w./v.) as solution and electrochemical techniques. The results of open circuit potential (OCP), polarization and electrochemical impedance spectroscopy (EIS) showed that presence of bauxite caused changes when it compared to water process results and the corrosion rate increased in the bauxite presence. The micrographs of specimens surface obtained by scanning electron microscopy (SEM) showed cracks formation in the oxide in the metal surface and this phenomenon may be responsible for increased corrosion in bauxite presence. The methodology described in this work show to be useful for the investigation of corrosion in pipelines.
Acesso aberto (Open Access)
Mapeamento de jazidas de bauxitas no Distrito Paragominas – Açailândia (PA-MA) pelo método da sísmica de refração
(Universidade Federal do Pará, 1986-12-29) BOLAÑOS ALVARADO, Ricardo Antonio; SCHIEL, Klaus Rainer; http://lattes.cnpq.br/1748862841375705
In the last 30 years, the mapping of bauxite deposits in Brazil has been carried out using drill holes. In this study, the refraction seismic method has been applied for the first time, with about 3000m of shallow profiles done on an experimental scale, at localities along the highway BR-10, as well as at Plato Esperança in the Jabuti region (PA), and near Açailândia county (MA), with the aim of delimitation of the bauxite layer. Although, the critical distance method has been used on some occasions to calculate thicknesses; this study has used the Generalized Reciprocal Method to process and interpret the data, to get the continuos delimitation of the layer being investigated. The GRM has an adventage compared to old traditional methods because, it delinates undulating refractors, infers undetected layers, and also is insensitive to dip angles up to 20 degrees. From the velocity analysis graph the velocity of the bauxite layer has been calculated, resulting in a mean of 840m/s. Using the time depth data it has been possible to map the bauxite, which has an irregular behavior and with a mean thickness of 5m. The geophysical research carried out at these areas turned out to be very important considering the fact that this method can be successfully applied to other regions having the same geological characteristics.
Acesso aberto (Open Access)
Micromorfologia, mineralogia e geoquímica da bauxita nodular de Trombetas – PA
(Universidade Federal do Pará, 2018-10-18) LIMA, José Diogo de Oliveira; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Brazil's main bauxite deposits are concentrated in the Amazon region, specifically in the state of Pará. The three main mines are located in Trombetas, Paragominas and Juruti, and they’re responsible for 85% of Brazil's bauxite production. Even with the favorable mineral scenario in Brazil and especially in the state of Pará, there are already companies that are currently competitive in the current market, they are seeking to develop studies of the characterization and use of nodular bauxite in this type of deposit. The ore, so far, is considered as marginal, it means low-grade ore in the mineral industry. In this context, this work sought to evaluate Trombetas deposits’ nodular bauxite from their texture, mineralogical and chemical characteristics as a possible aluminum ore. In the field, seven lithographic profiles were described on the mining fronts of Bela Cruz and Monte Branco mines belonging to ‘Mineração Rio do Norte’. Then, 19 samples were collected, which were described, photographed and prepared for mineralogical and chemical analyzes. The mineralogical phases were identified by X-ray Diffraction (XRD) and Scanning Electron Microscopy coupled to the Dispersive Energy System (SEM/EDS). The textural aspects involved optical microscopy and Scanning Electron Microscopy coupled to the Dispersive Energy System (SEM/EDS). The chemical analyzes were performed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), X-ray Fluorescence (XRF), titulometry and gravimetry. The profiles investigated comprise from the base to the top the bauxite horizon (HBX) which is represented by gibbsite concretions surrounded by a clay matrix. The overlapped bauxite nodular horizon subdivided into HBNB, HBNI and HBNT, is formed by gibbsitic nodules, of fine texture, that impresses solid and porcelanate aspect and they are surrounded by a clayey matrix. The clay cover (CAR) at the top is formed by a yellow clay, corresponding to Belterra Clay. In the profiles, the fragments > 0.500 and ~0.500 mm of the HBX and HBNB, HBNI and HBNT are essentially composed of gibbsite associated with kaolinite, hematite and anatase. The dominance of gibbsite in the fragments > 0.500 and ~ 0.500 mm of the HBNB, HBNI and HBNT, presents a potential of nodular bauxite as a possible aluminum ore. However the fragments < 0.500 mm, clayey matrix of HBX and HBNB, HBNI, HBNT and CAR are mainly composed of kaolinite associated with gibbsite, hematite, quartz and anatase. The kaolinite domain in the HBNB, HBNI, HBNT fragments < 0.500 mm, makes it difficult to consider them as possible aluminum ore. As for the heavy minerals (zircon, rutile and tourmaline), no contrast was found between the horizons and the clayey cover. The chemical composition consists essentially of SiO2, Al2O3, Fe2O3 and TiO2, which reinforce the main minerals identified and as these the contents differ according to the horizons. The concentrations of the trace elements are variable, V, Cr, Ga, Se, Zr, Nb, Mo, Sn, Hf, Ta, W, Hg, Bi, Th and U are above the crustal average in all fragments, clayey matrix of HBX, HBNB, HBNT and CAR. Trace elements such as V, Cr, Ga, Mo, Hg and Bi correlate positively with Fe2O3 (hematite and goethite). While Nb, Sn, Hf, Ta, Th, U, correlate positively with zirconium (zircon) and titanium (anatase). When normalized to the chondrites, the distribution curves present parallelism between the various fragments, clayey matrix of HBX, HBNB, HBNT and CAR, with curves that exhibit Eu anomaly, as well as an enrichment of the heavy rare earth elements (HREE) in front of the light rare earths elements (LREE). The data obtained in the investigated profiles of Bela Cruz and Monte Branco mines demonstrate broad similarity to Belterra clay-type nodular lateritic-bauxite profiles found in Amazon, where the clayey matrix of the nodules resembles textural, chemical (larger elements and traces) and mineralogical (including heavy minerals) with this covering clay.
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.