Navegando por Assunto "Material particulado"

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Acesso aberto (Open Access)
Aspecto geoquímicos do material particulado da pluma estuarina do rio Amazonas: fatores que controlam as interações com as águas oceânicas
(Universidade Federal do Pará, 2000-02-10) PEREIRA, Simone Baía; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429; https://orcid.org/0000-0001-7850-1217
The geochemical aspects addressed in this investigation are the determination of the chemical composition of the material in suspension in coastal waters under the influence of the mouth of the Amazon River, indicating the possible location of the source of suspended material, as well as the influences that it suffers along the continent transition -ocean. X-ray diffraction analysis indicated the predominance of kaolinite, illite and quartz clay minerals over the other identified inorganic components, observing the presence of chlorite, sometimes as a subordinate mineral in some samples, sometimes as a trace, and smectite in trace grades, which, like chlorite, is also present as a subordinate mineral. The centesimal mineralogical composition of the particulate material was estimated, associating the analytical results with X-ray diffraction data, using stoichiometric calculation, based on the scientific literature. The results obtained through the stoichiometric calculation confirm the tendency shown by the diffractograms. It is observed that the dominant clay minerals are kaolinite (maximum in 51.19%), associated with high levels of aluminum, distinguishing the dominance of this clay mineral in the sample in which this fact occurs, and illite (maximum in 42.43%) associated At high levels of potassium, when this clay mineral dominates the samples, the presence of iron and titanium colloids was also admitted. The content and nature of the organic matter associated with suspended sediments were evaluated, using elemental analysis for carbon, nitrogen and hydrogen, thermogram records and absorption spectra in the infrared region. In the sediments, organic compounds predominate (clay minerals, silica, iron colloids), with organic matter always having a content below 3.6%. Therefore, in interpreting the records of absorption spectra in the infrared region, the most intense bands are related to the dominant clay minerals in the material, that is, the illite and kaolinite mixture. Bands related to chemical bonds in clay minerals dominate in the infrared spectra. The clear and intense vibration band of the Si-O stretching, which extends from 1200 to 1000 cm-1, with its most significant developments around 1180 and 1034 cm-1, is well representative of structures of the illite and kaolinite types. And there is still a clear band, with weak folds around 950 to 915 cm-1, related to the Al-OH bond; bands around 790-800, 750-780, 640-690 cm-1; or in the range of 400 - 600 cm-1, the intense absorption bands recorded in the range of 4000 - 3400 cm-1, with their various developments, related to the bonds with hydroxyl, –OH, so common in clay minerals and an intense and average band recorded around 1640 cm-1 corresponding to the angular deformation of the HOH bond, a characteristic of constitutive water present in clay minerals. The infrared absorption spectra of humic and fulvic acids from different sources are similar but not identical. The (subtle) differences are the result of brief changes in their compositions. Perhaps the most interesting feature of the spectrum of humic acids is the appearance of intense and broad absorption bands related to the stretching vibrations of the C=O bond of several organic functional groups (carboxylic acids and their derivatives, aldehydes, ketones), in the range from 1709 to 1715 cm-1 and vibrations of aromatic compounds around 1600 to 1613 cm-1. The bands recorded around 1698 to 1701 cm-1 and around 1400 cm-1 indicate the presence of carboxyl and carbonyl groups. The most interesting aspects of the recorded spectra concern the appearance of clear (but weak) absorption bands in the range of 2959-2885 cm-1, attributed to methylene groups –CH2- of hydrocarbons; and the presence of a weak (but clear) band around 1385 cm-1 referring to the carboxyl and/or carbonyl groups. Leading to the conclusion that it is humic material present in organic matter from leaching and drainage of typical Amazonian soils, such as podzolic and latosolic. Elementary organic carbon contents range from 1.27% to 2.05%, while nitrogen contents range from 0.03% to 0.13%. These contents produce high C/N ratios (minimum 12.7% and maximum 68.3%) of material rich in cellulose decomposition products of vegetable origin. The integration of data from the chemical analysis of suspended matter with physical-chemical parameters of coastal waters and the variation in phosphorus levels (minimum of 0.06% to maximum of 0.71%, expressed in P2O5), associated with salinity variation (minimum of 24.31‰ and maximum of 39.19‰), used as limiting parameters, defined the existence of three characteristic zones of origin of suspended material: one predominantly terrigenous, one transitional and one predominantly oceanic biogenic.
Acesso aberto (Open Access)
Avaliação de parâmetros da qualidade do ar em um município amazônico do Estado do Pará
(Universidade Federal do Pará, 2025-02-21) ROSÁRIO, Abimael Silva do; MENDONÇA, Neyson Martins; http://lattes.cnpq.br/7534816053779593
This study evaluated the air quality in Barcarena, Pará, Brazil, throughout 2023, focusing on monitoring particulate matter concentrations (PM2.5, PM10, and TSP) at two points (P01 and P02) near an industrial complex with activities such as ore beneficiation and shipment, agricultural fertilizer storage and bagging, and grain shipment. These points were strategically chosen due to their location within the influence zone of various enterprises and the prevailing wind direction in the region. Samples were collected using High-Volume Samplers (HVS) over 24-hour periods, following guidelines from the Air Quality Technical Guide and CONAMA Resolution No. 491/2018. Collected data underwent descriptive and multivariate statistical analysis using Minitab Statistical software to determine PM2.5, PM10, and TSP concentrations and calculate the Air Quality Index (AQI). Results showed PM2.5, PM10, and TSP concentrations complied with the intermediate standards (PI-1) of CONAMA Resolution No. 491/2018 and the stricter limits of CONAMA Resolution No. 506/2024. The AQI for PM2.5 and PM10 was classified as "N1 - Good" throughout the study period, indicating no harmful effects on human health. Additionally, the study conducted a cost analysis of air quality monitoring campaigns, considering supplies, labor, and equipment, using ORÇAFASCIO software for budget development. This study contributes to air quality monitoring in areas with intense industrial activity, providing relevant data for environmental management and public health. Furthermore, the cost analysis offers valuable insights for planning and decision-making in similar projects.
Acesso aberto (Open Access)
Experimento em escala de emissão de poeira no processo de empilhamento
(Universidade Federal do Pará, 2022-03-25) CASTRO, Maycon Magalhães; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662; MACHADO, Luis Paulo Silveira; http://lattes.cnpq.br/0702289670734922; https://orcid.org/0000-0003-1587-3632
Dust emission can lead to health problems, explosion risk, material segregation and environmental pollution. Therefore, it is necessary to understand the parameters related to dust generation to improve particulate emission control techniques. Dust reduction based on spray spraying is the main method to prevent and control dust emission in ore stacking. Dust suppression techniques at conveyor belt transfer points can be subdivided into material spraying and trapping of fugitive particles. To analyze the parameters associated with dust generation during ore stacking, a scaled conveyor bench was developed for dust suppression tests via water spray. This installation is equipped with spray nozzles whose relative location on the belt can be adjusted and the speed of the conveyor can also be controlled. The spray jet is provided by a set of spray module and flow divider, allowing the variation of the system pressure and with the possibility of using suppressors, which can increase the efficiency of particle capture. Dust suppression performance is analyzed by monitoring strategic points with the highest dust emission. The results of this investigation show that dust generation increased as the drop height increased, it was observed that the region close to the pile emits a higher concentration of dust, due to the impact of the material flow on the stacking surface, in compared to the front region of the flow. The results after using the spray on the belt showed that the highest drop height (1600 mm) emitted the highest concentration of particles (3192.72 μg/m3) after spraying, on the material, the dust concentration reduced by about almost 70%, showing the efficiency of spray humidification. It was also observed that PF has a higher critical humidity than that of SF, as well as that it emits a higher concentration (1116.52 μg/m3) compared to Sinter feed (848.14 μg/m3), making it evident that by as it is a material with a smaller granulometry, the pellet feed tends to emit a higher concentration of particulates when handled.