Programa de Pós-Graduação em Geologia e Geoquímica - PPGG/IG

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2603

O Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA) surgiu em 1976 como uma necessidade de desmembramento do então já em pleno desenvolvimento Curso de Pós-Graduação em Ciências Geofísicas e Geológicas (CPGG), instalado ainda em 1973 nesta mesma Universidade. Foi o primeiro programa stricto sensu de Pós-Graduação (mestrado e doutorado) em Geociências em toda Amazônia Legal. Ao longo de sua existência, o PPGG tem pautado sua atuação na formação na qualificação de profissionais nos níveis de Mestrado e Doutorado, a base para formação de pesquisadores e profissionais de alto nível. Neste seu curto período de existência promoveu a formação de 499 mestres e 124 doutores, no total de 623 dissertações e teses.

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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)
Aproveitamento dos resíduos cauliníticos das indústrias de beneficiamento de caulim da região amazônica como matéria-prima para fabricação de um material de construção (pozolanas)
(Universidade Federal do Pará, 2007-12-18) BARATA, Márcio Santos; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
The Capim and Jarí regions are the most important kaolin district in the Amazon region, with the largest Brazilian reserves of high whiteness kaolin for paper coating products. Kaolin is obtained from three companies (IRCC, PPSA and CADAM) which produce annually around 1,000 M ton kaolinite-rich wastes derived mainly from the centrifugation phase of the process. The sludge is disposed on artificial sedimentary lakes covering large areas. Another type of kaolin waste is related to a non-processed iron-rich hard or flint kaolin, that overlays the so-called soft kaolin horizon (the main ore). These wastes exhibit appropriate characteristics for the production of high-reactivity metakaolin because they are extremely fine and composed of mainly by kaolinite. The main purpose of this work is to evaluate the feasibility of using these wastes as raw materials to produce mineral admixtures for OPC concretes. The wastes were firstly characterized for x-rays diffraction, thermal analysis, infrared spectroscopy, x-rays fluorescence and SEM. Three heating temperatures were evaluated: 750ºC, 850ºC and 900ºC, followed by pozzolanic activity tests based on traditional mechanical assays using Portland cement and hydrated lime mortars, and “Chapelle” test. The results showed that the more reactive pozzolans are those produced at temperatures that gave rise to higher LOI. The optimum burning temperature to produce metakaolinite from the hard kaolin was obtained at 750ºC while those from the Rio Jari and Rio Capim wastes were at 850ºC and 900ºC. The main reason is related to differences in the amounts of defects from three different wastes. The flint kaolin and Rio Jari waste are mainly composed by a “high-defect” kaolinite while the kaolinite from Rio Capim waste is a “lowdefect” kaolinite. In concrete test using different pozzolans those with metakaolin from wastes improved the mechanical and durability properties in comparasion to silica fume, a industrially manufactured metakaolin and reference concretes.
Acesso aberto (Open Access)
Arenito zeolítico com propriedades pozolânicas adicionadas ao cimento Portland
(Universidade Federal do Pará, 2011-08-29) PICANÇO, Marcelo de Souza; BARATA, Márcio Santos; http://lattes.cnpq.br/7450171369766897; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The proper use of pozzolans enables the production of special cements with lower manufacturing cost and higher durability in comparison with cements without mineral additions. It also enables significant gains in productivity and extending equipments life in the fabric, limestone reserves, and also helping in the reduction of CO2 release into the atmosphere. Zeolites have been used as pozzolanic material in mixtures with Fuller’s Earth and water in buildings from the ancient Roman Empire. Nowadays, there are many discussions involving pozzolanic reactivity of natural zeolites in the incorporation of Portland cement. In the Northeastern region of Brazil, sedimentary zeolites related to sandstones of the Parnaiba Basin wer discovered by the Geological Survey of Brazil in the 2000s. These sandstones are mainly composed by quartz, natural zeolites (estilbity) and clay (smectite). Preliminary studies have pointed that this sandstone may be used as pozzolanic material in Portland cements. The material must be previously sieved to remove quartz and thermally activated, since stilbite is a zeolite with low pozzolanic activity. The main objective of this work is to advance the understanding of the factors that govern the quality and performance of Portland cement modified with this zeolitic sandstone. For this work the structure was divided into three main stages, related to three specific objectives, so that the results are presented in the form of three scientific papers, described as follow: - Evaluation of the natural pozzolanic activity of the zeolitic sandstone to be used as mineral addition in the Portland cement. - The determination of which particle size provides the highest zeolite and smectite concentration, besides the calcination temperature that leads to a higer pozzolanic activity. - The establishing of the best amount of thermally activated zeolitic sandstone to be incorporated as a mineral addition in the Portland cement. During all phases, different instrumental techniques were used for the chemical and mineralogical characterization of the starting materials and products (sandstone + lime mortar, mortar with Portland cement + sandstone + Portland cement pastes sandstone), including: spectroscopy x-ray fluorescence, x-ray diffraction, thermal analysis and scanning electron microscopy. Heat-flow calorimetru assays were carried out to evaluate the physical properties, besides mechanical testing of compressive strength of cement mortars Porltand. In the first stage of the experimental program, the zeolitic sandstone was sieved into different granulometric fractions in order to remove the inert phases (quartz and other minerals), and concentrate the zeolite for further pozzolanic assays. In the second stage, after the first characterization of the samples, we used the zeolitic sandstone that passed in the # 200 and # 325 sieves and calcined at temperatures of 150º C, 300° C and 500° C. Finally, in the third stage, # 200 fraction was calcined at 500 ° C and mixed in different proportions (10, 20 and 30%) in the mortar. The results of the first stage, which culminated in the first article showed that the zeolitic sandstone accelerated the hydration of Portland cement due to the extreme fineness of the material. The sandstone showed pozzolanic activity, and estilbite is the main responsible for this behavior. However, the reactivity was slightly lower than the minimum required to be employed as pozzolan on an industrial scale. Additional studies are needed to ascertain if the thermal treatment between 400° C and 300o C could increase the pozzolanic activity of the sandstone due to the destruction of the crystalline structure of both estilbite and smectite. For the second stage, the results showed that the # 200 fraction was the most suitable because of the higher estilbite concentration (15%) in comparison to the # 325 ssample (2%). The calcination temperature of 500º C has provided the highest pozzolanic activity due to more effective destruction of the crystalline structure of both estilbite and smectite. More moderate temperatures of 150° C and 300° C were not enough. Mortars with the 200 # sample calcined at 500 ° C reached values smaller as those required for a material to be considered as a pozzolane, in this case, 6 MPa for mortar of lime and 75% for the pozzolanic activity index (IAP). The results showed from the third stage showed that the AZ2-3 mixture (10% of zeolitic sandstone incorporated in Portland cement type CPI-S), showed the best result of compressive strength and mineralogical properties of the samples suitable for the production a commercial cement type CPII-Z. In general, one concludes that the zeolitic sandstone from northeastern Brazil has the potential feasibility of producing a CPII-Z cement, whose pozolan contents ranges from 6 to 14% in the Portland cement, according to the ABNT - NBR 11578. Although the strength of the mortar with 10% of AZ2- 3 has reached resistance values close to the reference mortar with 100% of CPI-S, further studies should be carried out in order to find better proportion of sandstone and to meet the requirements for future commercialization.
Acesso aberto (Open Access)
Argamassas históricas de Belém do Pará.
(Universidade Federal do Pará, 2019-09-16) LOUREIRO, Alexandre Máximo Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The city of Belém, northern Brazil, known as the metropolis of the Amazon, was established on the banks of the Guajará Bay on January 12, 1616, with the denomination of Nossa Senhora de Belém do Grão-Pará, capital of the Grão-Pará province, now the state of Pará. Currently, Belém still has layers of lime mortar on its colonial and imperial buildings, which protect the secular structures and provide evidence of how this material was produced early in its history. Over the years, the deteriorating aspects identified in lime mortars, which damage both aesthetics and functionality, are related to the humidity, saline efflorescence, biological colonization, and/or anthropic actions. Once deteriorated, mortars require maintenance, consolidation, or replacement, which are difficult procedures that can lead to the use of inappropriate materials. Therefore, a good collect and characterization strategies of the original material is necessary for the restoration of historical monuments, because in studies focused on restoration science, the intervention strategy needs to include the use of building materials compatible with the original materials. Thus, the main objective of this doctoral thesis is to determine the characteristics and properties of historical mortars in Belém do Pará from the 18th and 19th centuries, as well as to propose a restoration mortars compatible with the historic mortars, which using industrial waste from Amazon Region. Therefore, this thesis was structured in three independent and complementary thematic articles, which addresses the topic of the historical mortars of Belém do Pará, since their characterization until the proposal of restoration mortars: 1) Investigation of the historical mortar of Belém do Pará, Northern Brazil; 2) How to estimate the binder: aggregate ratio from aerial lime-based historical mortars for restoration? and; 3) The use of industrial waste of the Amazon region in lime-metakaolin restoration mortars: compatibility assessment. Thus, the physical, chemical and mineralogical characteristics were determined, as well as the physical and mechanical properties of the historical material and the restoration material. The results of the historical mortars characterization pointing their main components, their functions and raw materials, besides indicating the analytical techniques used for binder: aggregate ratio quantification, which obtained good accuracy and reliability in your results. Moreover, the results show a wide range of characteristics and properties obtained through restoration mortars, which can serve as a benchmark for other studies or even for practical applications in historic masonry. Therefore, it was possible to identify the restoration mortars most compatible with the historical mortars of Belém do Pará, Northern Brazil.
Acesso aberto (Open Access)
Avaliação da influência dos cátions Na+, Ca2+ e Mg2+ na desativação de Ca, Mg-Bentonitas
(Universidade Federal do Pará, 2015-04-28) CARMO, Andre Luiz Vilaça do; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
In Brazil there is no occurrence of sodium bentonite, because of that, companies that explore this mineral raw material using a denominated sodium activation process, which is the exchange of cations in the interlayer space by Na+. Through this process, the bentonite present considerable improvements in their properties rheologies. However, after some time, these properties decline, which has been called deactivation. Thus, the objective of this study was to evaluate the influence of cations Na+, Mg 2+ and Ca2+ in the bentonite deactivation. For this, three bentonite considered calcic, from the state of Paraíba, and a magnesian, coming from the state of Maranhão, were studied in its natural form, activated and washed. The mineralogical phases of the samples were identified by X-ray Diffraction (XRD), chemical composition by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and cations in the interlayer by Cation Exchange Capacity (CEC). The rheological properties’ study was carried out by swelling. The XRD patterns showed that the dioctahedral smectite is the dominant mineral phase. There was the improvement in swelling results of all bentonite after the sodium activation, as well as subsequent decrease in the swelling value over 95 days (deactivation). Only one of the bentonite remained activated. The swelling results of washed bentonite showed increased for approximately the first 35 days, with subsequent decrease. The chemical composition results showed that a small amount of Na+ is removed from the washed bentonite. Furthermore, these results indicate that not only Na+ influences the swelling, but also Ca2+ and Mg2+ cations.
Acesso aberto (Open Access)
Avaliação das características físicas, químicas e mineralógicas da matéria-prima utilizada na indústria de cerâmica vermelha nos municípios de Macapá e Santana-AP
(Universidade Federal do Pará, 2008-09-30) SOUTO, Flávio Augusto França; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The activity ceramic of the State of Amapá still it presents very incipient, not managing to attend the market local. Among the main hindrances diagnosed, we can cite the next: 1) problems in the rental of lain new; 2) ignorance of the physical, chemical and mineralogical characteristics of the raw material (clay); 3) the lack of technical criteria in the raw material extraction. The work goals are: 1) Do the rising, register and to study clays main occurrences geological context for red pottery of the state of Amapá, the which ones are concentrate in the municipal districts surroundings of Macapá and Santana; 2) In occurrences selected, evaluate the chemical and mineralogical characteristics of the raw material, besides the technological-potteries properties, through which wishes the products improvement of red pottery (bricks and tiles). The work was developed in the area that embraces Macapá's Municipal districts and Santana in Amapá, limited by the latitudes (0º0’30”S and 0º3’30”S) and longitudes (51º12’30”W and 51º5’30”W), where are located the biggest numbers of ceramic of the State. The used materials in this work are coming of clays seized by 4 ceramic: Calandrine (CA) and Amapá Telhas (AT)(Macapá); União (U) and Fortaleza (F) (Santana), besides one regarding Corte de Estrada (CE) in Elesbão's District in Santana's Municipal district, representative sample of the Formation Barreiras. In the total were used 12 samples of the 5 cited places, distributed in profiles with average depth of 2,3 m. The methodology constituted in weigh 1 kg of brute sample, drying itself to 50ºC in stove, disintegrating and homogenizer the same. After this initial treatment, separate in four equal parts, it was separating 500 g for file and the remaining for analysis granulometric. Of the fraction clay it accomplished X-ray diffraction analysis (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), espectroscopy in the region of the infrared with transformed of Fourier (spectrums FTIR), chemical analysis (SiO2, Fe2O3, Al2O3, TiO2, CaO, Na2O, K2O, MgO and loss to the fire). For the technological rehearsals they used rules ABNT and were made bodies of proofs of 6x2x0,5cm to determination of the following parameters: color, water absorption (WA) , apparent porosity (AP), linear shrinkage (LS), apparent density (AD), Flexural Strenght (FS), liquidity limit (LL), plasticity limit (PL) and plasticity index (PI). The data obtained through the chemical analysis show great quantity of SiO2, Al2O3 + H2O, associates to the quartz and kaolinite. Values of Fe2O3, TiO2 suggest refractory and changes reduction in the coloration when burnt to 950ºC, besides being linked to the accessory minerals goethite, anatase and hematite. That was observed CaO and MgO are elements that drop for refractory and linked for montmorollonite and muscovite. Already Na2O and K2O, are fundentes important in vitrification process. For X-ray diffraction, thermal analysis and espectroscopy in the region of the infrared revealed the presence of the following minerals: quartz, illite, kaolinite, esmectite (montmorillonite), goethite, anatase. Clays rehearsed characterize for present elevated plasticity with plasticity index (PI) >15% and fraction silte high percentage. The water absorption measures, apparent porosity, lineal retraction and rupture tension to the inflection after burning in oven in the temperatures of 950ºC and 1050ºC, they presented values adequate for clays use in industry of red pottery. According to the measures obtained in the technological-ceramic rehearsals for the bodies of proofs burnt in the temperatures of 950ºC and 1050ºC, they contacted the next applications in clays studied: 1) Burning temperature to 950ºC - For masonry bricks 10 samples served (U-01, U-02, U-03, F-01, F-02, AT-01, AT-02, CA-01, CA-02, CA-03); for structural bricks 8 samples served (U-01, U-02, U-03, F-01, F-02, AT-02, CA-01, CA-03); and for tiles just 5 samples they presented inside the standards (U-01, U-03, F-02, F-01, AT-02). 2) Burning temperature to 1050ºC - 10 samples they presented inside the standards demanded for tiles production, masonry bricks and structural (U-01, U-02, U-03, F-01, F-02, AT-01, AT-02, CA-01, CA-02, CA-03).
Acesso aberto (Open Access)
As bauxitas nodulares do Platô Miltônia-3, Paragominas-PA
(Universidade Federal do Pará, 2017-12-12) CALADO, Waldirney Manfredi.; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
There are two distinct levels of bauxites on the Miltônia-3 plateau located at the Bauxite Province of Paragominas-PA. These levels are separated by a pseudopsolitic to concretionary ferruginous laterite (FL) horizon, marking a hiatus between two distinct cycles of the current bauxite profile formation. The bauxites of the upper level (2nd cycle of formation) have nodular to concrete characteristics whereas those of the basal level (1st cycle of formation) are composed by a more physically complete concrete bauxite (CB) added by another level of a more friable bauxite with clayey portions for its base (concrete bauxite with clayey bauxite - CBCB). It was noticeable the CNB located at the upper level of gibbsite-enriched horizon with low reactive silica and iron contents, which are very similar to those found on the horizon of the main bauxite ore (CB) of the profile. In field observations, on the survey fronts and in the drill holes it was found that this CNB is a gradation of the above Nodular Bauxite (NB) horizon. This gradation is observed by the increase in the size of the bauxite nodules, where their Fe-gibbsite pseudopsolites grows up by coalescence, decreasing the diffused iron and silica contents marked by the change in color from lilac-yellow to a red-orange color, to ocher, in higher depths. It is also noticeable a decrease until the complete disappearance of the Al-ferruginous pseudopsolites, in addition to the decrease of the volume of gibsytic-kaolinite clay at this level. Based on this study using macroscopic and microscopic petrography, SEM/EDS, XRD and chemical analysis, as well as Principal Component Analysis (PCA) and descriptive statistics, two evolution model proposals were developed on the genesis of the upper level of nodular bauxites of this lateritic-bauxite deposit, considering: Model (1) - Origin from the degradation of the original bauxites (1st Cycle), related to a 2nd Lateritization Cycle which consists of the preexistence of mature bauxite (CB), overlapped by FL, which was covered by "Belterra Clay". This new nodular level (NB) occurs through the coalescence process whereby the residual aluminous phase junction occurred, resulting from the migration of Fe and Si in solution out of this level and by the migration of the neighboring levels above the clayey overburden (CAP) and below that of FL and CB, forming and concentrating large scale gibbsite preferably and secondarily to kaolinite. With the continuous evolution of this level of NB, a maturation of the basal portion of this level is observed, forming the CNB whose nodules are interincreased, connecting locally, consuming neighboring levels above NB and levels below FL and CB, up to the total consumption of these; Model (2) - Its origin from a 2nd Lateritization Cycle, however from a later sedimentary deposition on the lateritic profile of the 1st Cycle. With the exposure of a source rock as a granitoid pluton (Cantão, Japiim, Jonasa, Ourém and Ney Peixoto of Neoproterozoic granites), gneiss (Archaean crystalline basement) or siliciclastic sediments (Itapecuru and Ipixuna Formations of the Upper Cretaceous), whose weathering degradation made it possible the generation of sediments of clayey nature preferentially kaolinite during the Paleogene until the beginning of the Oligocene. Migration of Fe, Si, Ca, Na, etc. occurred outside this level, preserving and concentrating the Al and O in situ, in addition to the residual Si. The process of coalescence allowed for the addition of the residual aluminous phase, preferentially concentrating the gibbsite and secondarily kaolinite, closing the first cycle of bauxite formation. Thereafter, there was a regional upwelling, followed by erosive processes that allowed for the exposure of this previously formed bauxite profile, under a seasonal climate, with an abundance of meteoric water and intense intercalated insolation, where the FL developed, of regional occurrence marking a hiatus between the formation cycles of these bauxites. New regional retraction movement, which allowed for the deposition of sediments of siliciclastic origin, which served as source rock for a new bauxite formation cycle during the Upper Miocene. They may be the same rocks from which physical and chemical degradation provided sediments for the 1st cycle of bauxite formation. Repeating the coalescence process of the residual aluminous phase, with the large scale development preferably of the gibbsite and secondarily kaolinite, closing the second cycle of NB and CNB formation.
Acesso aberto (Open Access)
Caracterização geológica, mineralógica, química e física do caulim da Mina da RCC-Rio Capim Caulim (PA)
(Universidade Federal do Pará, 2000-07-24) SOUSA, Daniel José Lima de; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
Acesso aberto (Open Access)
Caracterização geoquímica de arsênio total em águas e sedimentos em áreas de rejeitos de minérios de manganês no município de Santana - estado do Amapá
(Universidade Federal do Pará, 2003-02-27) LIMA, Marcelo de Oliveira; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
Acesso aberto (Open Access)
Caracterização química, mineralógica e aplicações potenciais da bentonita associada a basaltos intemperizados da Formação Mosquito, Bacia do Parnaíba, Sul do Maranhão
(Universidade Federal do Pará, 2010-03-01) PAZ, Simone Patrícia Aranha da; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
In the city of Formosa da Serra Negra (Maranhão state, northern Brazil), extensive outcrops of weathered basalts are found, which show enough clay contents to be a potential bentonitic material. The basalts are related to the Jurassic Mosquito Formation (Parnaíba Sedimentary Paleozoic Basin). In this work these saprolites were referred as Formosa bentonite, and the main purpose was to characterize their mineralogical and chemical composition for further potential applications. X-ray diffraction results show that montmorillonite is the main mineral present along with minor amounts of hematite, K-feldspar, magnetite and kaolinite. The Formosa Bentonite was compared with four reference bentonites: Chocolate and Bofe (from the famous Paraiba state deposits), SWy-2 and SAz-1 (from the Clay Mineral Society). Although these bentonites have showed a wide chemical, mineralogy and texture variation, common for such material, the similarities were convincing to increase the expectations of a new Brazilian bentonite. The present montmorillonite was successfully pillared with aluminium polyhydroxications. Results showed that the pillarization process increased the basal spacing of the natural clay from 15.3 to 18.7 Å and the surface area from 55.9 to 180.3 m2/g, proper for catalytic and adsorption applications. Adsorption tests were also carried out for Cu2+ in aqueous solution using the natural and pillared Formosa Bentonite. Surprisingly, in the three evaluated process variables (pH, contact time and adsorption equilibrium) the natural bentonite exhibited a better adsorptive capacity in comparison with the pillarized one. This is of special value if one intends to use these bentonites in natura, for instance, for wastewater treatment. They are environmentally correct, economically viable and assure low cost.
Acesso aberto (Open Access)
Comportamento de metais pesados e nutrientes nos sedimentos de fundo da Baía do Guajará e Baía do Marajó
(Universidade Federal do Pará, 2010-01-28) HOLANDA, Nielton de Souza; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
Human activities influence the physical and chemical characteristics of water, sediments and organisms in aquatic environments located in industrialized areas and high population density. With the increasing use of estuaries as a reservoir for a large amount of waste, coastal and estuarine ecosystems are gradually being subject to significant impacts. The bottom sediments play an important role in the investigation of these impacts since it has the ability to retain chemical species and inorganic. The objective of this research is to study the geochemical behavior of metals in the bottom sediment of the Bay of Guajará, Guama River and the Bay of Marajo. The two regions were chosen for their opposite characteristics: a Guajará Bay Area (1) under strong anthropogenic influence and Marajó Bay Area (2) considered the reference. We collected 83 points in Area 1 and 60 points in Area 2. Determined chemical concentrations of the following metals: Ba, Cr, Cu, Fe, Pb, Ni, V and Zn, and also the levels of nitrogen, carbon, organic matter, total phosphorus and phosphorus bound to organic compounds. Area 1 shows the average content of nitrogen of 0,08 %, mean levels of carbon and organic matter from 1,51 % and 2,60 %, respectively. The concentration of phosphorus and phosphorus bound to organic compounds 307 mg / kg and 126 mg / kg, respectively. The concentration of metals showed the following values: Ba (529 mg / kg), Cr (91 mg / kg), Cu (17 mg / kg) , Fe (6,82 %), Ni (32 mg / kg), Pb (27mg / kg), V (120 mg / kg) and Zn (69 mg / kg). Area 2 shows the average content of organic matter 1.70 % of carbon and nitrogen 0,98 % and 0,08 % respectively. The concentration of phosphorus and phosphorus bound to organic compounds 193 mg / kg and 7 mg / kg, respectively. The concentration of metals showed the following values: Ba (596 mg / kg), Cr (102 mg / kg), Cu (21 mg / kg) , Fe (8,31 %), Ni (40 mg / kg), Pb (28 mg / kg), V (141 mg / kg) and Zn (85 mg / kg). The carbon and phosphorus (0,98 %, 193 mg / kg), respectively found in area 2 were lower than those found in area 1 (0,51 %, 307 mg / kg) and demonstrate the influence of effluents that are released in the estuary Guajarino. In both areas there is the same downward trend in levels: Fe2O3> Ba> V> Cr> Zn> Ni> Pb> Cu. In area 1 were found higher metal alone while in area 2, with the major averages, the distribution is homogeneous, two areas in the metals has a slight tendency to concentrate where there is a higher content of organic matter.
Acesso aberto (Open Access)
Cristaloquímica da sodalita Bayer derivada de bauxitas com alta sílica reativa de Paragominas-Pa
(Universidade Federal do Pará, 2016-05-24) MELO, Caio César Amorim de; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
In the Paragomina’s region, as well as the whole Brazilian north, gibbisitic bauxite deposits commonly shows high amount of kaolinite. The processing of this bauxites (called as High Silica Bauxites - BASR) became a challenge because in the conventional conditions of the Bayer process, the kaolinite is undesirably leached by NaOH solution, and then precipitated as sodalite. The formation of this phase brings a significant increase in process costs, both by increasing the processing time as the irreversible loss of NaOH robbed from the system to form sodalite, which is then discarded in the red mud. Given this metallurgical problem this study aimed to investigate the crystal chemistry of sodalite formed in conventional conditions of the Bayer process, so that, from these results, studies to reduce these losses of the process and facilitate the processing of BARS can be developed in the future. The materials investigated were kaolinitic gangues from 4 lithologies of an exploration well in Miltonia 3 mine (BN, BNC, BC and BCBA), as well as a kaolin from IMERYS S.A. The digestions were carried out in Teflon-lined, stainless steel autoclaves, using 1 g of solid material, 25 mL of NaOH solution and at a temperature of 150ºC in an oven. The NaOH concentration and the reaction time ranged from 2,5 to 5,0 M and 60 to 420 min, respectively. Then the solid material was characterized by XRD, DTA/TG, FTIR, SEM and ICP-OES. The results of the starting materials showed that the kaolin sample is essentially constituted by kaolinite, which has a high structural ordering degree. All the samples of kaolinitic gangue showed the same minerals: gibbsite, kaolinite, hematite, goethite and anatase. By the observation of the XRD patterns and DTA curves can be noted that the BN and BNC samples are more reactive than the others, possibly due a lower structural ordering degree and particle size. In the experiments with kaolin, it can be observed that are formed not one, but two sodalite phases, which coexist practically throughout the whole process and tending to an equilibrium phase. These two phases differs themselves by the amount and behavior of the NaOH and H2O molecules within the framework. The results of the refinments showed that these phases were: basic sodalita with cell parameter (ao) ~ 8,96 Å, which is predominant in the initial stages of the transformation, and hydrosodalite with ao ~ 8,85 Å dominant in the secondary stage (mainly in 180 min). The XRD results from kaolinitic gangues showed that in 60 min there was no full kaolinite/sodalite conversion, and the sodalite patterns in BN and BNC were more intense and well defined than BC and BCBA, confirming that these samples have more reactive kaolinites. The increase of the reaction time and NaOH concentration provided a slight increase of the structural sodalite order. It may be noted that in almost all experiments the only phase formed was basic sodalite. The exceptions were the lithologies: BCBA and BC, which hydrosodalite was formed in the highest time of reaction and NaOH concentration, thus showing that this phase is directly associated with a higher time, concentration and crystallinity of kaolinite available in the reaction medium. It can be observed that throughout the reaction, in shorter time and concentration it is not possible to achieve a balance, which leads to a constant interchange of predominant phase in the system. In the higher time and concentration experiments, a balance is virtually reached, in order that it cannot be observed separated diffraction peaks. However there is no significant increase of the structural ordering even for extreme times as 3 days of reaction. The ammonium chloride experiments showed that this reaction medium allows the formation of more crystalline phases than all others achieved in this research. However, it did not result in the diminished of the sodium consumption.
Acesso aberto (Open Access)
Desenvolvimento do processo de síntese da zeólita A e da sodalita a partir de rejeitos de Caulim da Amazônia com aplicações em adsorção
(Universidade Federal do Pará, 2011-08-31) MAIA, Ana Áurea Barreto; POLMANN, Herbert; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; 7501959623721607
The minimization of industrial and domestic residues is one of the great challenges that human kind is facing. Several proposals are released for this intention, ranging from improving industrial processes in order to minimize waste generation, besides their use in the production of new materials. In this context, this work has the main purpose of using kaolin residues from industries located in the Pará State, northern Brazil, for the production of zeolites (e.g., zeolite A and sodalite). These companies exploit kaolin from the world famous Capim and Jari regions and produce high quality kaolin for the paper industry. Preliminary mineralogical and chemical characterization of the Capim (KC) and Jari (KJ) kaolin residues was carried out as the basis for further zeolite A and sodalite synthesis. The study of thermal activation of kaolinite at various temperatures was carried out using 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR), in order to to produce highly reactive metakaolinite from KC and KJ residues. The zeolite NaA synthesis was performed for varying parameters such as time and Na/Al relation. Temperature was kept constant at 110 °C for the two starting materials (KC and KJ). The KA, MgA and CaA phases were prepared by ionic exchange from phase NaA. In the sodalite synthesis, kaolinite was used directly as starting material and two temperatures (150 and 200 °C) were utilized. The Na/anion and Na/Al relations were maintained constant and varied, respectively in the reaction mixture for KC and KJ. The removal performance of mixed metal ions (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) in aqueous solution was investigated by adsorption process on zeolite NaA prepared from KC an KJ as proposal to reduce environmental problem with industrial wastewater streams that contain heavy metals. The XRD results showed that the residues are mainly composed of kaolinite with extremely low impurity level. For comparing the residues from two regions, Capim and Jari verified that the KC displays a high degree of structural order. This difference displays significant influence in the ideal heating temperature to produce a material with high amount of 4-coordinated A1. As a result, the ideal temperature to produce highly reactive metakaolinite is: 600 °C for Jari kaolin residue and 700 °C for Capim kaolin residue. Zeolite A was produced with a large degree of structural order and was generally obtained as the only zeolitic product. The following synthesis conditions were used: Na/Al ratio of 1.64 and time 18 and 20 h for KC and KJ, respectively. The cationic exchange process between Na from zeolite A and K, Mg and Ca in solutions displays efficient result and with XRD data, was verified that the KA, MgA and CaA phases were obtained with success. The sodalite series was produced from KC and KJ and by FTIR was confirmed the chloride, sulphate and carbonate insertion in its structure. The KJ kaolinite displays high reactivated in the sodalite synthesis, it could be explicated by its low degree of structural order. The sorption capacity of heavy metals mixture (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) on zeolite NaA, produced from KC and KJ, display satisfactory values. The results revealed that the Langmuir model is more appropriate than Freundlich in the fit of the experimental data. Zeolite A, produced from residues (KC and KJ), could be excellent materials for the treatment of wastewater.
Acesso aberto (Open Access)
Dos minerais aos materiais de arquitetura e processos de degradação: edifícios e ornamentos metálicos dos séculos XIX e XX em Belém do Pará
(Universidade Federal do Pará, 2015-06-16) PALÁCIOS, Flávia Olegário; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The use of iron in architecture was intensified during the second half of the XVIII century in Europe, and its influence spread over many countries in growth, such as Brazil. Belém (PA) was one of the cites that received the larger amount of building and ornaments imported, especially from England, France, Belgium and Portugal, during the XIX e XX centuries. Currently, Belém holds the largest number of iron architecture heritage remnants in the country. Despite of having great importance in construction techniques, many of these buildings were disassembled and remain on the wait for restoration processes. Also, studies about theses constructions only focus on historical and visual discussion, with no understanding of construction materials, causing empirical restoration processes. The knowledge about these materials is important to the detailed study of historical metal alloys, and different fabrication techniques, as well as weathering action, aiming future restoration processes with scientific bases. The main objective of this research is to understand the historical metals, their diversity in iron architecture and fabrication processes, and also weathering action in iron buildings and ornaments from the XIX and XX centuries in Belém. Thus, the following specific objectives were established: a) physical, chemical and mineralogical characterization of alloys and pathologies; b) identification of different kinds of alloys, in order understand the production types; c) determination of metallurgy evolution imported to the Amazon. The materials chosen for this research came from three different sites, due to their representativeness and diversity of pieces and origin: Mercado de Ferro do Ver-o-Peso building; the former chalet from the State’s Press; and the ornaments from tombs and mausoleums of the Soledade Cemetery. The methods used were Scanning Electron Microscopy (SEM) for physical characterization and punctual chemical analysis; and X-Ray Diffractometry (XRD) for mineralogical analysis. The results were presented in three scientific papers indicating: 1) iron alloys mostly composed by ferrite; 2) textural variations exhibiting four types for the building group: nodular cast iron, gray cast iron type E, wrought iron and gray cast iron type B; 3) three classification of gray cast iron for the ornamental group of diverse origins, among A, B and D; 4) corrosion as main weathering action, and products constituted by goethite and hematite; 4) remnant paint coats, formed by metallic zinc, and its products of alteration represented by zincite and hidrozincite. Through the results of this research it was possible to indicate the evolution of processes in iron architecture production, and enrich this research area with scientific information, as subside for future restorative processes.
Acesso aberto (Open Access)
Espeleotemas fosfáticos em cavernas ferríferas de Carajás e uma nova ocorrência de esfeniscidita
(Universidade Federal do Pará, 2017-02-26) ALBUQUERQUE, Alan Rodrigo Leal de; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
Iron ore mining in Brazil is important for maintaining the country’s positive trade balance. Iron ore is among the country’s main exports, and as a result of intense extraction, new environmental policies have been implemented. In an attempt to balance economic activity and environmental conservation, an inventory and a relevance-based classification of caves were implemented in 2008 as criteria for environmental licensing of mining ventures. This implementation motivated the present study of phosphate speleothems in iron caves in the Carajás Mineral Province. The objectives of this study were to describe the phosphate minerals and their formation processes based on data from geochemical and petrographic analysis in concert with X-ray diffraction, differential scanning calorimetry coupled with thermogravimetry, infrared and scanning electron microscopy. We studied eight caves where the development of phosphate speleothems appeared to be directly associated with the presence of guano. DSC-TG curves allowed us to identify two phosphate groups: leucophosphite-spheniscidite, which displayed two endothermic events at 323.4 and 400 °C attributed to OH and NH4 removal, respectively, and strengite-phosphosiderite, which displayed no such events. Infrared spectra allowed us to identify the NH4 functional group, related to the presence of spheniscidite, based on absorbance bands centered at 1430 and 3040 cm-1. Values of the unit cell parameters for spheniscidite, calculated by Rietveld refinement, revealed dimensions and angulations slightly lower than those reported in the literature (a = 9.803 Å, b = 9.722 Å, c = 9.858 Å, β = 102.78°). These smaller values are attributed to increased substitutions of K for NH4 and Al for Fe. Based on the geochemical analysis, significant enrichment in P2O5, Zn, Ni and Rb was detected, suggesting that bat guano was a potential source of these elements. Guano decomposition releases phosphoric acid, which percolates the lateritic substrate reacting and substituting iron hydroxides for phosphate minerals, with simultaneous assimilation of metals that had been bioaccumulated and excreted by bats.
Acesso aberto (Open Access)
Gênese das bauxitas nodulares do Platô Miltônia-3, Paragominas - PA
(Universidade Federal do Pará, 2017-12-12) CALADO, Waldirney Manfredi; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
There are two distinct levels of bauxites on the Miltônia-3 plateau located at the Bauxite Province of Paragominas-PA. These levels are separated by a pseudopsolitic to concretionary ferruginous laterite (FL) horizon, marking a hiatus between two distinct cycles of the current bauxite profile formation. The bauxites of the upper level (2nd cycle of formation) have nodular to concrete characteristics whereas those of the basal level (1st cycle of formation) are composed by a more physically complete concrete bauxite (CB) added by another level of a more friable bauxite with clayey portions for its base (concrete bauxite with clayey bauxite - CBCB). It was noticeable the CNB located at the upper level of gibbsite-enriched horizon with low reactive silica and iron contents, which are very similar to those found on the horizon of the main bauxite ore (CB) of the profile. In field observations, on the survey fronts and in the drill holes it was found that this CNB is a gradation of the above Nodular Bauxite (NB) horizon. This gradation is observed by the increase in the size of the bauxite nodules, where their Fe-gibbsite pseudopsolites grows up by coalescence, decreasing the diffused iron and silica contents marked by the change in color from lilac-yellow to a red-orange color, to ocher, in higher depths. It is also noticeable a decrease until the complete disappearance of the Al-ferruginous pseudopsolites, in addition to the decrease of the volume of gibsytic-kaolinite clay at this level. Based on this study using macroscopic and microscopic petrography, SEM/EDS, XRD and chemical analysis, as well as Principal Component Analysis (PCA) and descriptive statistics, two evolution model proposals were developed on the genesis of the upper level of nodular bauxites of this lateritic-bauxite deposit, considering: Model (1) - Origin from the degradation of the original bauxites (1st Cycle), related to a 2nd Lateritization Cycle which consists of the preexistence of mature bauxite (CB), overlapped by FL, which was covered by "Belterra Clay". This new nodular level (NB) occurs through the coalescence process whereby the residual aluminous phase junction occurred, resulting from the migration of Fe and Si in solution out of this level and by the migration of the neighboring levels above the clayey overburden (CAP) and below that of FL and CB, forming and concentrating large scale gibbsitepreferably and secondarily to kaolinite. With the continuous evolution of this level of NB, a maturation of the basal portion of this level is observed, forming the CNB whose nodules are interincreased, connecting locally, consuming neighboring levels above NB and levels below FL and CB, up to the total consumption of these; Model (2) - Its origin from a 2nd Lateritization Cycle, however from a later sedimentary deposition on the lateritic profile of the 1st Cycle. With the exposure of a source rock as a granitoid pluton (Cantão, Japiim, Jonasa, Ourém and Ney Peixoto of Neoproterozoic granites), gneiss (Archaean crystalline basement) or siliciclastic sediments (Itapecuru and Ipixuna Formations of the Upper Cretaceous), whose weathering degradation made it possible the generation of sediments of clayey nature preferentially kaolinite during the Paleogene until the beginning of the Oligocene. Migration of Fe, Si, Ca, Na, etc. occurred outside this level, preserving and concentrating the Al and O in situ, in addition to the residual Si. The process of coalescence allowed for the addition of the residual aluminous phase, preferentially concentrating the gibbsite and secondarily kaolinite, closing the first cycle of bauxite formation. Thereafter, there was a regional upwelling, followed by erosive processes that allowed for the exposure of this previously formed bauxite profile, under a seasonal climate, with an abundance of meteoric water and intense intercalated insolation, where the FL developed, of regional occurrence marking a hiatus between the formation cycles of these bauxites. New regional retraction movement, which allowed for the deposition of sediments of siliciclastic origin, which served as source rock for a new bauxite formation cycle during the Upper Miocene. They may be the same rocks from which physical and chemical degradation provided sediments for the 1st cycle of bauxite formation. Repeating the coalescence process of the residual aluminous phase, with the large scale development preferably of the gibbsite and secondarily kaolinite, closing the second cycle of NB and CNB formation.
Acesso aberto (Open Access)
Geoquímica regional multielementar aplicada aos campos da saúde humana e ambiental na porção continental da folha SA.22-X-D - Belém, Região Nordeste do Pará
(Universidade Federal do Pará, 2008-05-12) VIGLIO, Eduardo Paim; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The present work was done together with PGAGEM – National Program of the Medical Geology and Environmental Geochemistry Research of CPRM - Geological Survey of Brazil, on the 1:250.000 that took place in northeast of the Pará State and the northwest of Maranhão State. This study focused on the Belém Sheet SA.22-X-D, on the same scale. With regional approach, 74 drainage basins with around 100km² were sampled for water and stream sediments. These were analyzed for 33 and 53 elements respectively in order to understand the distribution pattern on the environment. Some points of the public water distribution supply systems where also studied. The water samples were maintained by refrigeration and analyzed by ICP-OES in the LAMIN laboratory of CPRM in Rio de Janeiro. Physiochemical parameters such as pH, conductivity, dissolved oxygen, salinity and temperature were measured in situ. The stream sediments samples were collected in various points of the drainage (composed sample), and analyzed at Acme Laboratory using three different analytical methods: hydret generation connected to ICP-OES, for As and Se; mercury vapor generation connected to atomic absorption spectroscopy – CVAAS for Hg and ICP-OES for the others elements. To all the geochemical maps generated for the water samples was added the curve of maximum allowed concentration for the CONAMA/ Brazilian Health Ministry/WHO. It was also possible to define on the opposite margins of the Guamá river two regions with contributions from distinct source areas. On the south portion the primary source area is the Barreiras Formation. On the north portion, the primary source area are sands so called “post Barreiras” from the Pleistocene and submitted to intense lixiviation, with grades always below the background values, where the totality of the original rock elements was removed. The comparison of water and stream sediments results from the same point shows that the migration of the elements from the sedimentary rocks to the water, with pH values varying from 3.6 to 5.5, is a process actually working. More detailed isotopic studies must be done to confirm that despite smaller grades in the right margin, right on the more populated region of Belém city, these grades are anthropogenic, mainly for Pb and Cu. The data of PGAGEM Project for the public water distribution supply systems was reevaluated. Areas of high concentration and time of exposure were indicated using an expression called the Exposition Grade, the product of the concentration of a chemical element times the daily average ingestion of water (two liters) times the time of exposure. The Exposition Grade Factor defined the localities of Barcarena, Vila dos Cabanos and Moju (located in Belém Sheet), as 3 among 10 localities submitted to the highest exposure risk in all the PGAGEM area. It introduces the concept of ample and restrict geogenic anomaly. The first refers to the natural distribution pattern of elements on the environment. The second refers to both anthropogenic and natural distribution. Twelve basins where detected with ample geogenic anomalies for Al, B, Cu, Fe and Pb, and restrict geogenic anomalies for Cd, Co, Cr, F and Hg. These results are presented on the Geochemical Orientation for the Territorial Management and Public Health Map. This work generated a Geochemical Atlas of the continental portion of the Belém Sheet 1:250.000 scale with analytical results tables and over one hundred geochemical maps. This work confirms that regional and multi-element geochemical surveys outline the distribution patterns of the chemical elements in Nature, and therefore may predict and explain human health problems due to natural factors. This kind of study turns out to be a very useful tool in preventive implementation of Health and Territorial Management public policies.
Acesso aberto (Open Access)
Mapeamento geoquímico da bacia do rio Itacaiúnas, Província Mineral de Carajás: Assinatura geoquímica dos blocos crustais e implicações para recursos minerais e meio ambiente
(Universidade Federal do Pará, 2020-10-26) SALOMÃO, Gabriel Negreiros; DALL'AGNOL, Roberto; http://lattes.cnpq.br/2158196443144675; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
Multielement geochemical surveys (MGS) when combined with advanced data processing techniques and robust statistical analysis, are important tools for understanding the environment. In the last decades, its application in mineral exploration is well established and, in the last decades, it has shown remarkable relevance for environmental studies linked to sustainable territorial management, particularly in the establishment of geochemical background concentration values. The definition of background values has been widely used to demonstrate the inconsistencies of laws and regulations, which establish concentration limits for potentially toxic elements in the environment, often without taking into account the complex spatio-temporal heterogeneity of each region. In Brazil, many MGS were, and continue to be carried out mostly by the Companhia de Pesquisa de Recursos Minerais (CPRM, Geological Survey of Brazil) in different parts of the national territory, although they are still scarce in the Amazon region. The present study is associated with a large geochemical mapping project called the Geochemical Background of the Itacaiúnas River Basin (GBI) carried out by the Instituto Tecnológico Vale (ITV). The Itacaiúnas River Watershed (IRW) is located in the largest mineral province of Brazil, the Carajás Mineral Province, and it is particularly relevant for geochemical studies, because the distribution of chemical elements in this region and the influence of the great geological domains on that distribution are not known. The purpose of this research is to investigate the influence of large geological domains in the chemical composition and geochemical signature of stream sediments of the IRW. In addition, it is intended to generate geochemical maps, identify the associations and geochemical processes in stream sediments, define geochemical compartments for the whole watershed, and determine background concentrations for the analyzed elements, taking into account the geochemical compartments and/or geological domains of the study area. In order to achieve these objectives, the stream sediment geochemical data from the GBI-ITV project obtained in the whole IRW in 2017, and those from two CPRM projects in the center-south portion of the BHRI with sampling in the years 2011-2012 were used. These projects were conceptualized at different scales and sample density; however, the sampling techniques and analytical procedures are similar. Stream sediment sample collections were carried out in active water stream, at surface levels from 0 to 10 cm deep, and preferably in the middle of the channel. Sample preparation included the following steps: drying, disaggregation, quartering and sieving. Approximately 50 g of the fraction <0.177 mm was sent to accredited laboratory for chemical analysis. In the laboratory, the samples were submitted to digestion with aqua regia, and then 51 elements were analyzed (Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, Re, S, Sb, Sc, Se, Sn, Sr, Ta, Te, Th, Ti, Tl, U, V, W, Y, Zn and Zr) via Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The geochemical data was submitted to descriptive statistical analysis and some non-parametric statistical tests. Several graphs (e.g., boxplots, histograms, probability and dispersion) were generated for the main chemical elements. Multivariate statistics (e.g., correlation matrices, cluster analysis and factor analysis) were used to investigate the main existing multi-element associations. To determine geochemical background values, modern methods widely used in the specialized literature were employed. Geospatial information was processed and managed in an environment of geographic information systems, in which different cartographic and geoprocessing techniques were used to generate geochemical distribution maps. In general, it was found that, on the scale of geochemical surveys conducted by ITV and CPRM, there is no conclusive evidence of contamination related to human activity, but very strong evidence of a marked geological contribution in the geochemistry of the stream sediments of the IRW. A consistent and replicable methodology was used to identify the main multi-element associations and to define IRW’s surface geochemical compartments. The geochemical associations identified are controlled by the geological domains, by specific lithologies in restricted areas and/or by biogeochemical factors acting in the study area. The delimitation of geochemical compartments revealed a strong similarity with the simplified geological domains of the basin. Geochemical background concentrations were determined for the IRW and its geological domains. Among the methods suggested for determining the background, the Median ± 2*Median Absolute Deviation showed the most consistent and realistic results. In addition, it is considered essential to define reference values based on geochemical compartments, or even a simple geological setting. The assumption of a single uniform reference value for a wide area is inappropriate. The background values proposed in this research may assist environmental impact studies by monitoring anomalous concentrations of potentially toxic elements, which exceed background concentrations. In addition to its scientific interest, the results presented here can be useful to assist local surveys of geochemical prospecting and in the formulation of environmental policies in the Brazilian territory.
Acesso aberto (Open Access)
Mapeamento geoquímico e estimativa de Background em solos na região da Província Mineral de Carajás – Leste do Cráton Amazônico, Brasil
(Universidade Federal do Pará, 2018-03-09) SALOMÃO, Gabriel Negreiros; DALL’AGNOL, Roberto; http://lattes.cnpq.br/2158196443144675; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
This research is linked to the project 'Geochemical Background of the Itacaiúnas River Basin' under development by the Vale Institute of Technology Sustainable Development (ITVDS). In Brazil, geochemical surveys have been carried out mainly by the Companhia de Pesquisa de Recursos Minerais (CPRM – Brazilian geological survey), which has executed some projects focused on the region of Carajás, the largest mineral province in Brazil and in which the Itacaiúnas River basin is located. One of these projects, titled 'Evaluation of the Potential of the Strategic Mineral Resources of Brazil', carried out in the year 2012, covered the region of Canaã dos Carajás and generated a large collection of soil geochemical data. As such data were made available, the main purpose of this dissertation is to explore as much information as possible to elaborate multi-elemental geochemical maps based on interpolation techniques and to establish geochemical background values of the elements in soils of the target region of the CPRM survey. 225 soil samples, along with 32 duplicates, were collected in that project in an area of approximately 4,500 km2. The 80 mesh (0.177 mm) fraction of these samples was submitted to aqua regia digestion and 53 elements (Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Pd, Pt, Rb, Re, S, Sb, Sc, Se, Sn, Sr, Ta, Te, Th, Ti, Tl, U, V, W, Y, Zn, Zr) were analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) for the major and minor elements and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for the trace elements. The analytical data provided by the CPRM were initially submitted to a quality control by means of Residual Standard Deviation (RSD) calculation for each duplicate. Then, the simple substitution method was used for the values beyond the limit of detection, followed by uniand multivariate statistical analyzis, including descriptive statistical treatments, identification of outliers via Grubb test, normality tests (Lilliefors and Kolmogrov- Smirnov), correlation and cluster analysis. All statistical analyzis previously highlighted were conducted by STATISTICA® and SPSS® softwares. To determine the values of threshold and geochemical background and graphical representation were used the methods boxplot and cumulative frequency curve methods (Minitab® and Excel® software) and the iterative techniques 2 and calculated distribution function (freeware Visual Basic macro denominada VB Background®). For the construction of geochemical maps, the World Geodetic System 1984 (WGS84) coordinate system was adopted as standard. Spatial representations followed techniques of interpolation according to the kriging or inverse distance weighting (IDW) methods. 43 analyzed elements were submitted to the statistical tests, having been left aside Au, B, Ge, Na, Pd, Pt, Re, Se, Ta e Te, because they presented ≥90% of the analytical data below the limit of detection. Correlation analyzis revealed 14 moderate correlations (0.650> r ≥ 0.575) and 19 high correlations (r ≥ 0.650), generally consistent with usual geochemical associations in geological environments such as Cr-Ni, Cu-Ni and U-Th. The cluster analysis discriminated seven clusters, at a linkage distance of 0.8, with evident geogenic origin, as for example the group composed of Cr, Ni and Mg, typical of mafic-ultramafic rocks. The geochemical maps allowed to identify occurrences of several anomalies in soils, interpreted as being of geogenic origin. Thus, U, Th, La and Ce enrichment was found in soils derived from sub-alkaline neoarchean granites, for example Estrela, Serra do Rabo and Planalto granites, and Cr and Ni in soils from mafic-ultramafic rocks of Luanga and Vermelho complexes and the Cateté Suite. Elements typically associated with anthropic activities, such as P, Zn, Mn, Ba and Pb, as well as potentially toxic elements (EPT), such as Al, As, Bi, Cd, Co, Hg, Mo and Sn, did not generally exhibit, anomalous concentrations and, when this occurred, these appear to be due to geological conditions. Among the methods used to estimate the background values of the 43 evaluated elements, the iterative technique 2 was the one that presented the best result. In cases where this method could not be used, the values obtained by the calculated distribution function (As) and the boxplot representation (Hg and S) were adopted as background. The cumulative frequency curve showed to be a useful graphical technique in the identification of outliers and multiple thresholds. The 225 samples were grouped into five classes that revealed the close linkage between the background values and the geology of the region: 1) Sub-alkaline granites (39 samples); 2) Sedimentary and metasedimentary rocks (28 samples); 3) Gneisses and associated granitoids (70 samples); 4) Metamafic, intermediate and banded iron formation (BIF) (80 samples); 5) mafic-ultramafic rocks (8 samples). With the results obtained, it is concluded that, in the scale of the survey carried out, there is no conclusive evidence of contamination related to human activity, but rather strong evidence of a marked geogenic contribution in the soils of the study area.
Acesso aberto (Open Access)
Materiais híbridos orgânicos-inorgânicos: argilominerais, óxidos e polímeros
(Universidade Federal do Pará, 2018-03-23) CAVALCANTE, Manoella da Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The interaction on a nanometric scale of molecular or polymeric species with inorganic substrates constitute the basis for obtaining hybrid materials. The development of these materials represents an emerging and interdisciplinary topic between the frontiers of life sciences, materials and nanotechnology. The combination of these two materials, organic-inorganic, produces a new material with improved properties and structures essentially different from its individual components. Constituted by a continuous phase (matrix), being plastics or cellulose, and an inorganic phase, such as clay minerals or oxides. several papers have been published obtaining these materials with improved properties: traction modules, gas barrier, flame retardants, density, melt strength, electrical conductivity, etc. Capable of making industry flexible and rigid products and in the manufacture of electronic materials (wire and cable coatings manufacture of sensors / actuators), vaccine production, among others. The most clay minerals used in the synthesis of hybrid materials are the species montmorillonite, clay but others can also be used, such as illite and palygorskita. In the state of Maranhão, northeastern Brazil, there are several occurrences of clay minerals, most notably smectite, illite and palygorskite. Among these clay minerals two new occurrences have already been identified and characterized by the UFPA Group of Applied Mineralogy (GMA), such as Bentonite Formosa and Palygorskite, which are abundant in the region and do not yet have an application. In addition to a new occurrence of illite not yet characterized in the region of the municipality of Barão de Grajaú (MA). Another material with great potential for obtaining nanomaterials is the vanadium pentoxide, having intrinsic features such as alignment of the magnetic field, and redox system such as gel elasticity, enabling application in the electronics industry for the manufacture of batteries and electrochromic displays for sensors/actuators. In Brazil, vanadium pentoxide began to be produced in 2014 by Maracás S/A. Currently, its consumption is focused on the production of special steels for the manufacture of aircraft structures and the aerospace industry. At the national level the production and development of hybrid materials and platforms for use in high-tech industry is small. Thus, the development and improvement of nanomaterials is necessary using as starting material and clay minerals national occurrence oxides. Within this context, this thesis aimed to develop a study on application of three clay minerals (Mg-montmorrillonite, illite and Palygorskita) from northeastern Brazil, besides vanadium pentoxide in the processing of hybrid materials using as poly matrix (methylmethacrylate) (PMMA ) and cellulose nanofibers. For this, the methodology of this work was divided into three parts: The first one consisted of the collection or synthesis, treatment and characterization of the individual materials (clay minerals, vanadium pentoxide, methyl poly (methacrylate) and cellulose). The second was to obtain hybrid materials clay mineral-PMMA (AP) and vanadium pentoxide cellulose (VC) and the third one was mainly to evaluate the thermal and mechanical properties of the AP hybrids and the electrochromic properties of the VC films. The characterization of the samples confirmed the predominance of Mg-montmorillonite, Illita and Palygorskita. The natural clay and organophilic fraction were used to obtain 12 samples with common and elastomeric PMMA to perform the physical-chemical tests focusing mainly on flammability and traction. By means of XRD measurements it was possible to verify that there was interaction between the two organic-inorganic phases, and that in the elastomeric PMMA there was a better dispersion of the clay minerals. The tests carried out on these materials indicated that the hybrids exhibit intrinsic thermal and mechanical behavior of each material possibly related to the type of structure present in the inorganic phase, contributing to the increase or decrease of Tg, Tm, flammability and traction. Four V2O5-cellulose films were obtained and characterized. Electrochromic tests were conducted in the films that presented better performance. It was possible to verify that there was interaction between the nanofibers of vanadium pentoxide and cellulose maintaining the electrochromic property of the oxide. Potentiometric measures were found that after 30 and 100 cycles the films remained flexible and maintained their properties. In this way, this work concluded that it is possible to obtain hybrid materials with clay minerals coming from the northeastern region of Brazil and can adapt their thermal and mechanical properties according to their application. The same was observed for the VC films that presented satisfactory results and that can be used in displays and / or flexible sensors.

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