Este trabalho apresenta uma análise dos possíveis impactos ambientais negativos decorrentes da instalação do aterro sanitário industrial e dos lagos de resíduos de bauxita do Parque Industrial do Consórcio do Alumínio do Maranhão - ALUMAR, em termo de contaminação das águas superficiais e subsuperficiais das bacias hidrográficas envolvidas, baseado em um grupo de atributos, considerando um modelo exploratório. A partir de dados espaciais (ensaios laboratoriais e de campo) e mapas elaborados pela ALUMAR, nas escalas 1:10.000 e 1:20.000, foram selecionados, analisados e sintetizados todos os atributos de interesse em um conjunto de 12 documentos cartográficos. Num passo seguinte, foram investigados os aspectos do meio físico (colapsividade, erosão, afundamento, estabilidade do maciço e infiltração) e as características físicas do aterro sanitário industrial e do lagos de resíduos de bauxita (posição em relação ao nível de água, posição em relação ao substrato rochoso, aspectos construtivos e técnicas de impermeabilização), os quais podem gerar condições de instabilização no sistema e nas fontes, provocando vazamento. Frente à análise dos dados obtidos, os acidentes na área do aterro sanitário industrial e dos lagos de resíduos de bauxita, podem ser ocasionado por infiltração e erosão. A contaminação decorrente de vazamentos nesta região não atingirá níveis profundos devido à presença de material silte arenoargiloso da Formação Alter do Chão, pouco permeável, que impedirá o deslocamento dos contaminantes em profundidade, promovendo o espalhamento lateral controlado pelas camadas que comportam-se como drenos, e assim os contaminantes poderão ser interceptados pelos canais de drenagem, poluindo as águas superficiais e subsuperficiais e, por conseqüência, todos os componentes do meio ambiente. / This work presents an analysis of the possible negative environmental impacts associated to the installation of industrial sanitary landfill and of lakes of bauxite residues at the Industrial Park of Aluminum Consortium in Maranhão - ALUMAR, in terms of contamination of superficial waters and groundwater, based on a group of attributes, and considering an exploratory model. From laboratories, field data and maps elaborated by ALUMAR, at scales 1:10,000 and 1:20,000, the attributes were put into 12 cartographic documents. The analyses were done considering collapsible, erosion, settlement, slope stability and infiltration conditions of the areas, technological characteristics o f industrial sanitary landfill of the bauxite waste lakes and spacial position in relation to groundwater level and rocky substratum. According to the analysis of the data obtained, the accidents in the area of industrial sanitary landfill and of the lakes of bauxite residues can be caused by infiltration, due to both a deficiency in its impermeabilization system and erosion. The current contamination in this area will not reach deep levels due to the presence of clayey sand silt layers of the Alter do Chão Formation, and low permeability, which impede the movement of pollutants in depth. On the other hand, this layer should promote the lateral dispersal controlled by the layers which behave as drains. The pollutants can be intercepted by the drainage channels, polluting the superficial waters and groundwater and, as a consequence, all the components of the environment.

Planting trees in mining zones for post-mining rehabilitation is of great interest. Therefore, it is important and necessary to study the current state of the air, water, and soil environment in the mine exploited area. Therefore, this article studied and assessed the environmental state in Tan Rai bauxite mining area at Bao Lam district, Lam Dong province through the environmental components of air, water and soil, as a basis for selection of suitable crops for post-mining rehabilitation. The research result showed that the air quality in the bauxite mining area met the standard 3733/2002/QĐ-BYT. Almost monitoring parameters of surface water and wastewater is within the allowed threshold of Vietnam standards. However surface water had a sign of TSS and COD pollution (TSS and COD at the Danos stream after the received point of wastewater from No.6 tailing lake were 1.6 times and 1.07 times higher than those in standard). Ground water was polluted by Coliform (20-63,3 times over standard) and cation NH4 + (1.1-1.5 times over standard); Soil in exploiting region was strongly impacted, soil profile has changed, red-yellow soil dominated, soil fertility is pretty high, pHH20 and pHKC were from acid to neuter. This studied environment state is very suitable for planting pine and acacia. These results will be useful references, as a basis for orientation of post-mining rehabilitation. / Việc trồng cây xanh để phục hồi các vùng mỏ sau khai thác hiện đang rất được quan tâm. Do vậy, việc nghiên cứu hiện trạng môi trường không khí, nước và đất ở vùng khai thác mỏ là rất quan trọng và cần thiết. Bài báo nghiên cứu đánh giá hiện trạng môi trường vùng khai thác mỏ Bauxite Tân Rai, huyện Bảo Lâm, tỉnh Lâm Đồng thông qua các thành phần môi trường không khí, nước, đất, làm cơ sở cho việc lựa chọn loại cây trồng phù hợp cho công tác phục hồi môi trường sau khai thác mỏ. Kết quả nghiên cứu cho thấy, chất lượng môi trường không khí tại vùng khai thác mỏ Bauxite đạt tiêu chuẩn 3733/2002/QĐ-BYT. Hầu hết các thông số quan trắc của nước mặt và nước thải đều nằm trong giới hạn cho phép theo tiêu chuẩn Việt Nam, tuy nhiên môi trường nước mặt cũng đang có dấu hiệu ô nhiễm TSS và COD (TSS và COD tại suối Danos phía dưới điểm tiếp nhận nước thải hồ quặng đuôi số 6 tương ứng gấp 1,6 lần và 1,07 lần so với tiêu chuẩn). Nước ngầm đang bị ô nhiễm Coliform (vượt quy chuẩn cho phép từ 20-63,3 lần) và NH4 + (vượt quy chuẩn cho phép từ 1,1-1,5 lần); Đất tại khu vực khai thác bị tác động mạnh mẽ, phẫu diện đất bị thay đổi, đất đỏ vàng chiếm ưu thế, đất có độ phì khá, pHH2O và pHKCl từ chua đến trung tính. Kết quả hiện trạng môi trường như vậy là phù hợp với trồng thông và keo. Những kết quả này là tài liệu tham khảo hữu ích, làm cơ sở cho việc định hướng phục hồi đất sau khai thác mỏ.

Titre de l'écran-titre (visionné le 22 janvier 2024) / En droite ligne avec ce qui constitue le cœur de la recherche en gouvernance multi-niveaux dans le secteur extractif, cette thèse porte sur les relations partenariales entre l'État (niveau national), l'entreprise multinationale (niveau international) et les communautés (niveau local) en Guinée dans la région bauxitique de Boké. De manière plus précise, elle explore les rapports asymétriques de pouvoir entre les divers acteurs dans la construction de la gouvernance minière dans la région de bauxite de Boké. Pour ce faire, elle s'appuie sur une série de concepts théoriques à savoir responsabilité sociale des entreprises, acceptabilité sociale, retombées locales, innovation institutionnelle, asymétrie de pouvoirs, policy story et policy learning pour nous éclairer à partir d'une perspective multidisciplinaire sur le sens de la gouvernance multi-niveaux dans la région de bauxite de Boké. La thèse parvient à démontrer que les relations partenariales entre les acteurs tendent progressivement à devenir de moins en moins asymétriques à travers un passage d'une gouvernance imposée à une gouvernance de plus en plus négociée. Ce changement de situation est perceptible au niveau de l'État qui a conduit des réformes juridico-institutionnelles profondes afin d'instaurer un régime miner orienté vers une redistribution plus équitable et durable des bénéfices miniers auprès des communautés mais aussi vers une exigence plus importante en matière de transparence et d'imputabilité de la part des entreprises. La thèse a cherché à 'illustrer dans le cas de Boké, cette dynamique relationnelle complexe entre les acteurs, jalonnée de progrès indéniables en matière de rapport de réciprocité mais aussi de dysfonctionnements structurels minant finalement la gouvernance multi-niveaux. La thèse est composée de trois articles, le premier de nature conceptuelle et les deux autres empiriques en s'appuyant sur l'étude de cas de la région de bauxite de Boké pour illustrer l'évolution dans les temps des relations entre l'État, l'entreprise à travers la Compagnie de Bauxite de Guinée (CBG) et les communautés. Alors que le premier article nous souligne le contexte national et nous démontre l'évolution politico-institutionnelle de l'État en matière de gouvernance minière naviguant entre réformes innovantes et dysfonctionnements récurrents, le second démontre les processus de changement et s'attache à convaincre que malgré ces dysfonctionnements, les pouvoirs publics s'acheminent progressivement vers une gouvernance d'instruments de politiques publiques négociée avec les autres acteurs. Le troisième article orgo-centré, témoigne à partir du cas d'étude du système de la CBG, de toute la complexité relationnelle entre elle et l'État d'une part mais aussi entre elle et les communautés de la région de Boké. Cette thèse propose ainsi un éclairage original sur les relations État-entreprise-communautés dans un contexte extractif africain. / In line with what constitutes the core of multi-level governance research in the extractive sector, this thesis focuses on the partnership relations between the State (national level), the multinational enterprise (international level) and communities (local level) in Guinea in the bauxite region of Boké. More specifically, it explores the asymmetrical power relations between the various actors in the construction of mining governance in the Boké bauxite region. To do this, it relies on a series of theoretical concepts namely corporate social responsibility, social acceptability, local benefits, institutional innovation, power asymmetry, policy story and policy learning to enlighten us from a multidisciplinary perspective on the meaning of multi-level governance in the Boké bauxite region. The thesis succeeds in demonstrating that partnership relations between actors gradually tend to become less and less asymmetrical through a transition from imposed to increasingly negotiated governance. This change in situation is perceptible at the level of the State, which has led to profound legal-institutional reforms to establish a mining regime oriented towards a more equitable and sustainable redistribution of mining profits to communities but also towards a greater demand for transparency and accountability on the part of companies. The thesis sought to illustrate in the case of Boké, this complex relational dynamic between the actors, punctuated by undeniable progress in terms of reciprocity relationship but also structural dysfunctions ultimately undermining multi-level governance. The thesis is composed of three articles, the first of a conceptual nature and the other two empirical based on the case study of the Boké bauxite region to illustrate the evolution over time of the relations between the State, the company through the Bauxite Company of Guinea (CBG) and the communities. While the first article highlights the national context and shows us the politico-institutional evolution of the State in terms of mining governance navigating between innovative reforms and recurrent dysfunctions, the second demonstrates change processes and seeks to convince us that despite these dysfunctions, the public authorities are gradually moving towards a governance of public policy instruments negotiated with other actors. The third article orgo-centered, testifies from the case study of the CBG system, of all the relational complexity between it and the State on the one hand but also between it and the communities of the Boké region. This thesis thus offers an original light on state-company-community relations in an African extractive context.

Bayer processing of bauxite employed for production of alumina yield a residue red-mud. The worldwide annual-rate of red-mud generation is approximately 120 million tons, and most of this is stockpiled. Red mud is rich in elements like aluminum, titanium and rare earths, in addition to the major iron-bearing constituents. The objective of this research is to explore such a strategy to extract Iron as fine particulate magnetite. Pyrometallurgical reduction experiments using carbon mixtures and a novel hydrometallurgical route are experimented. Reduction experiments performed with petroleum coke as a reductant resulted in incomplete reduction. The ‘optimal conditionsÂ’ for gaseous state reduction are determined to be: a processing temperature of 540oC ± 10oC, partial pressures CO (g) and CO2 (g) each of 0.070atm (bar) ± 0.001atm.(bar)/ inert diluent-gas: N2 (g), for a conversion-time of 30min. A mathematical-model was developed on the basis of unidirectional-diffusion of CO2 (g) within the CO2 (g)–CO (g)–N2 (g) gas-phase of the porous product-layer. Magnetic separation applied to the optimally reduced sample in: obtaining a magnetic portion with high iron and non-magnetic portion containing nonferrous (Al, Ti) is not successful. This finding was subsequently attributed to the nanometer length-scales crystallites of the predominant iron-containing phase, hydrated ferric-oxide(s) as determined by STEM micrographs. In addition, the presence of substitution for Fe3+ by Al3+ and Ti3+/4+ are determined with the help of MÖssbauer spectrograms. A hydrometallurgical route involving selective leaching and precipitation of iron in red-mud is tried. Red-mud is leached in oxalic acid at: 95˚C, 15 % Pulp density, 2.5 h leaching time, 1.5 pH. Kinetic studies yielded the leaching mechanism to be predominantly fluid film control. Ferric oxalate in the leach liquor is reduced to insoluble ferrous oxalate selectively using Iron powder. The ferrous oxalate formed is ~98 % pure. The precipitated ferrous oxalate is magnetically separated and reduced in Nitrogen atmosphere to form fine particulate magnetite. Additionally an economic feasibility study was conducted for the hydro and pyro alternatives to produce magnetite using Monte Carlo Simulations by imparting uncertainties in various input cost components. A traditional process was also compared to the proposed approaches for Total Capital Investment (TCI), Total Product Cost (TPC), Net Present Value (NPV) and sensitivity analysis. ~52 % reduction in Total product cost, 46 % reduction in Total Capital Investment was achieved for the hydrometallurgical process when compared to the traditional approach.

[Truncated abstract] Landforms rehabilitated after bauxite mining can be vulnerable to soil loss by water erosion processes. On most rehabilitated sites, management controls such as deep ripping, contour mounding and landscaped sub-catchments limit erosion. Despite these measures, severe gully erosion that is anecdotally associated with steep slopes can damage rehabilitated areas and affect downstream drinking water resources. A review of erosion dynamics reveals that gullies develop episodically and in a non-linear manner. They often initiated as a near surface process and are influenced by natural climatic drivers. Despite this, local site characteristics including soil and landform can predispose an area to gully erosion. Moreover, erosion models, becoming more-widely utilized within the mining industry, may provide useful tools with which to measure, analyse, and manage gully erosion. One of these models, SIBERIA was tested to determine its suitability for application a tool to help manage erosion risk. We first surveyed 26 eroding and erosion-prone rehabilitated hillslopes to determine the common form and setting for gully erosion on these rehabilitated bauxite mines. A conceptual model was developed to include and explore the interplay between the common causes of the gullies surveyed. The conceptual model accounts for slope steepness but suggests that additionally, certain triggers and threshold effects operating under different site conditions are as influential (or even more influential) than slope steepness as determinants of gully erosion occurrence and severity. ... Soil properties and soil erodibility had some subtle influence on landform stability and erosion risk. The most-erodible media occurred where either: mine floor material was mixed with topsoil/ overburden; and/or the topsoil/overburden layer was thin or its coverage is patchy resulting in slaking subsoil, hardsetting soil and surface crusts. When erodible surface media were combined with steeper (>8[degrees]) or longer (>50 m) slopes or with any major erosion trigger, rill and gully development was greatly intensified. The SIBERIA simulation model was calibrated and its simulated outputs were compared to known locations of gully erosion on a steep, rehabilitated pit from the Willowdale mine. At a resolution of one metre, SIBERIA was able to simulate the approximate dimensions of gullies. However, SIBERIA could not simulate the exact location of individual gully headcuts. Additionally, SIBERA was able to simulate the effect of different microtopographic surface treatments but this was only achieved by increasing the grid resolution to 25 cm and reducing the size of the area simulated due to model constraints. Locations of gully headcuts were overlain onto a grid-based, Digital Elevation Model (DEM) using a Geographic Information System (GIS). The spatial distribution of gully headcut locations was compared to DEM derivatives such as slope and flow accumulation. Positive, and predictive relationships allow between the steepness of the slope of the pre-mining landform and the cell count of the area contributing to flow (catchment), as determined by GIS, may allow a mine scale indication of erosion risk using simple GIS desktop analysis.

Στην παρούσα Διατριβή παρουσιάζεται η μελέτη της δυνατότητας αξιοποίησης της ερυθράς ιλύος, ΕΙ, η οποία παράγεται κατά τη διαδικασία παραγωγής της αλουμίνας με τη διεργασία Bayer, για την παραγωγή δομικών παραδοσιακών κεραμικών, κύρια τούβλων και κεραμιδιών. Μελετήθηκαν αργιλούχα μίγματα με ΕΙ για ποσοστά ΕΙ από 10%κβ έως και 100%κβ.Επιγραμματικά, για την ΕΙ, πραγματοποιήθηκε χαρακτηρισμός και μελέτη της θερμικής συμπεριφοράς της. Για τα μίγματα της ΕΙ με αργιλούχες Α' ύλες, πραγματοποιήθηκε θεωρητικός σχεδιασμός τους, ενώ μελετήθηκε η επίδραση των σταδίων ανάμιξης και λειοτρίβησης, η επίδραση της ΕΙ στην πλαστικότητα, η θερμική συμπεριφορά, οι φυσικομηχανικές ιδιότητες των τελικών κεραμικών, η επίδραση της θερμοκρασίας και ατμόσφαιρας όπτησης καθώς και η περιβαλλοντική τους συμπεριφορά. Πραγματοποιήθηκαν επιπρόσθετα πιλοτικές δοκιμές παραγωγής τούβλων και κεραμιδιών. Τα αποτελέσματα της διατριβής, οδήγησαν στην ανάπτυξη μιας βέλτιστης διεργασίας παραγωγής κεραμικών με ΕΙ, η οποία αφορά στο σχεδιασμό του μίγματος με ΕΙ και την όπτησή του σε αναγωγικές συνθήκες. / In the present thesis, Bayer's process red mud, RM, is being studied as an additive and raw material for the production of heavy clay ceramics, mainly bricks and roofing tiles. A number of clay mixtures with RM were studied, for a RM content ranging from 10wt% to 100wt%. In summary, RM was characterised and studied for its thermal behaviour whereas, for the clay mixtures with RM, their design is provided, and the effect of comminution steps, the effect of RM on plasticity, their thermal behaviour, the influence of firing temperature and atmosphere, the physicomechanical properties of the end bodies, as well as their environmental behaviour are studied. In addition, pilot plan scale experiments were performed for the production of bricks and roofing tiles. The results of this thesis, led to the development of an optimised process for the production of ceramics with RM, which emphasises on the design of the body mixture as well as on the firing in reducing conditions.

Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-15T19:43:41Z No. of bitstreams: 1 TeseMA.pdf: 4330905 bytes, checksum: 6cb5f6465c74b22135d461ab86d86511 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:55:34Z (GMT) No. of bitstreams: 1 TeseMA.pdf: 4330905 bytes, checksum: 6cb5f6465c74b22135d461ab86d86511 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:55:39Z (GMT) No. of bitstreams: 1 TeseMA.pdf: 4330905 bytes, checksum: 6cb5f6465c74b22135d461ab86d86511 (MD5) / Made available in DSpace on 2016-09-16T19:55:47Z (GMT). No. of bitstreams: 1 TeseMA.pdf: 4330905 bytes, checksum: 6cb5f6465c74b22135d461ab86d86511 (MD5) Previous issue date: 2015-08-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This paper describes an integrated process for recovering aluminum, iron, titanium, sodium and silica from red mud through a hydrometallurgical treatment sequence. The disposal of red mud, which is the largest waste produced by the aluminum industry, causes considerable environmental problems, and impacts costs greatly. This work presents a proposal to deal with it. Firstly, red mud is subjected to calcination at the 500-600°C range (thermal activation) so as to modify the structure of the metals present in red mud and make the attack with sulfuric acid easier. Next, the red mud is mixed with sulfuric acid and calcinated at 250- 300 °C (acid calcination). After digestion, the metal sulfates in the cake are dissolved by leaching with water and separated from the silica by filtration . Two routes to recuperate the leached metals are presented here, and the second one is analyzed economically. In this second method, silica is separated by filtration and all other metals in the leached solution are precipitated through a hydrometallurgical process in the form of their oxides. The remaining products present high purity level, thus being more easily marketed. / Este documento descreve um processo integrado para a recuperação de alumínio, ferro, titânio,sódio e sílica numa sequência de tratamento hidrometalúrgico da lama vermelha. A eliminação de lama vermelha, que é a maior resíduos produzidos pela indústria de alumínio, provoca consideráveis problemas ambientais e impactos custa muito. Este trabalho apresenta uma proposta para lidar com eles. Em primeiro lugar, a lama vermelha é submetida a calcinação no intervalo de 500-600 ° C(ativação térmica), para modificar a estrutura de metais presentes na lama vermelha, o que facilita o ataque com ácido sulfúrico. Em seguida, a lama vermelha e misturada ,com ácido sulfúrico, e levada à calcinação com ácido sulfúrico, a 250- 300 ° C (calcinação ácida). Após a digestão, os sulfatos de metal no bolo são dissolvidos por lixiviação com água, e separados da silica por filtração. São apresentados dois métodos para recuperação dos metais que foram lixiviados,sendo que a segunda alternativa, apresentada é avaliada ecônomicamente. A sílica é separada por filtração , e todos metais da solução lixiviada , são separados por processos hidrometalurgicos, na forma dos seus respectivos óxidos, apresentam grande pureza ,sendo facilmente comercializáveis

Cerca de 230 milhões de toneladas de bauxita são produzidas por ano e, destas, 60 milhões são provenientes de operações que beneficiam esta bauxita usando água como meio para separar as frações mais finas. Como consequência do beneficiamento, estima-se que mais de 25 milhões de toneladas de rejeito sejam dispostas todo ano. Estas frações têm grandes quantidades de caulinita, um argilomineral de difícil desaguamento. Estes sólidos estão tipicamente em uma suspensão com água a cerca de 15% de concentração em massa antes de operações de desaguamento. As formas de desaguamento variam, bem como as opções de disposição. Este texto discorre sobre opções de desaguamento como sedimentação natural, espessamento, filtragem e centrifugação. Também se discorre sobre alternativas de disposição. Estas são condicionadas pela concentração de sólidos do material a ser disposto e são a disposição hidráulica em diques ou reaterro na mina. Após a descrição de cada uma das alternativas, são feitas análises de combinações destas formas de desaguamento e disposição, além de uma avaliação do fluxo de caixa livre descontado acumulado para cada uma. Esta abordagem, feita para um caso específico, permite avaliar qual opção implica em menor despesa financeira para a operação. Foram feitas considerações para avaliar características não econômicas de cada uma das operações, como o consumo de água, área ocupada pelo depósito, perigos de cada opção e seus descomissionamentos. A opção que apontou menor desembolso no período da operação, bem como a minimização de perigos, é o desaguamento com centrífugas e disposição do material reaterrando áreas lavradas. / More than 230 million tonnes of bauxite are produced each year and, from these, nearly 60 million come from operations that use water to beneficiate the ore, separating the finer fractions. By reason of this mineral treatment, it is estimated that more than 25 million dry tonnes of reject are disposed each year. The finer fractions have high kaolinite concentrations, a challenging to dewater mineral. These solids are typically in a suspension with about 15% solids concentration in mass before any dewatering. Both the dewatering options and disposal possibilities may vary. This text discusses dewatering options such as natural settling, thickening, filtering and centrifugation. It also describes alternatives of disposing the material. These options depend on the water concentration and consist of hydraulic disposition or using the dewatered material as mine backfill. After describing each alternative, an analysis of possible combinations among those is made along with an accumulated discount free cash flow evaluation for each one. Considerations were made to evaluate non-economic characteristics of each operation including the water consumption, surface occupied, operational hazards, decommissioning and closure. The option that has shown the lowest cost during the life of the operation, simultaneously reducing operational hazards is dewatering with centrifuges and using the material as backfill in mined out areas.

Orientador: Francisco Sergio Bernardes Ladeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-09T09:17:40Z (GMT). No. of bitstreams: 1 Leonardi_FernandaAparecida_M.pdf: 23677977 bytes, checksum: 4c5706f5e614cdc53595822a8c7cceb9 (MD5) Previous issue date: 2007 / Resumo: Muitos trabalhos no âmbito da geomorfologia buscaram associar níveis altimétricos às superfícies de erosão. Partindo-se da teoria de Davis, de topos concordantes ou topos de mesma altitude (uma abordagem clássica baseada em pontos de maior altitude), realiza-se a associação destas superfícies com a ocorrência de perfis bauxíticos, identificando-se assim as antigas superfícies ou paleosuperfícies. Portanto, este trabalho tem como objetivo principal correlacionar as superfícies geomórficas com os perfis de alteração, no caso, os Perfis Lateríticos-Bauxíticos, utilizando-se destes como marcos estratigráficos. A partir do trabalho de campo, no Planalto de Poços de Caldas encontrou-se três tipos de Perfis Bauxíticos: de Serra, de Campo e Retrabalhados. Os Perfis de Serra são mais espessos que os Perfis de Campo, com maior teor de alumínio e menor teor de sílica, indicando que provavelmente se formaram no topo, onde a drenagem permitiu uma maior lixiviação e concentração de alumínio. O que diferencia um Perfil de Serra do de Campo é uma camada de argila existente entre a rocha e a bauxita. Esta camada de argila não possui estruturas da rocha e é bastante homogênea, enquanto, em todo o depósito encontram-se volumes com estrutura concêntrica e sistemas de fraturas preservados do material de origem. Os Perfis Bauxíticos Retrabalhados possuem sua origem nos Perfis de Serra, pois nestes materiais a concentração de alumínio é elevada e a de sílica é baixa. Ao correlacionar os Perfis Bauxíticos, com as prováveis superfícies geomórficas, segundo a altimetria, percebe-se que não há uma ordem, os perfis estão distribuídos aleatoriamente nas bordas e no interior da área, em diferentes patamares do relevo, onde especialmente observa-se a ocorrência de Perfis Bauxíticos de Serra posicionados em altimetrias de Perfis de Campo e Perfis Retrabalhados posicionados sobre Perfis de Serra, acima dos 1.400 metros. O controle estrutural observado em campo, na literatura e nas cartas topográficas nos mostra zonas de falhas comuns, podendo-se associar esta descontinuidade do perfil bauxítico com essas movimentações. Uma das evidências mais claras são os padrões de drenagem que são preferencialmente controlados pelos alinhamentos estruturais que seccionam o embasamento. Muitas movimentações, provavelmente, ocorreram anteriormente à formação dos perfis bauxíticos, entretanto ocorreu uma reativação das falhas, pois se verificou que as falhas cortam os materiais associados aos Perfis de Serra, Perfis de Campo e em alguns casos, afetam os níveis de Perfis Retrabalhados, indicando que a atividade tectônica não se restringiu apenas em moldar o quadro (junto com o clima) dos processos erosivos que afetaram os perfis in situ, mas avançou para além dos eventos de formação dos materiais lateríticos depositados / Abstract: Many works in the geomorphology scope have tried to associate the elevation levels with the erosion surfaces. Starting from Davis' accordance tops or similar elevation theory (a classical aproach based in points of higher elevation) it is proposed the association of these surfaces with the occurrence of Bauxite Profiles, identifying the old surfaces or paleosurfaces. Therefore, this work has the main objective of correlating the geomorphic surfaces with the alteration profiles, in this case the Bauxite Laterite Profiles, applying these as statigraphic marks. Through the field work in Poços de Caldas Plateau were found three types of Bauxite Profile: Rim, Plateau and Reworked Profiles. The Rim Profiles are thicker than the Plateau Profiles, with bigger amount of aluminium and smaller of silica, indicating that they probably were formed in top, where the drainage allowed a bigger leaching and concentration of aluminium. The aspect that distinguishes a Rim from a Plateau Profile is a clay layer between the rock and the bauxite. This clay layer does not have rock structures and it is rather homogeneous, while, in the whole deposit were found contents with concentrical structure and fractures systems preserved from the material of origin. The Reworked Bauxite Profiles have their origin in Rim Profiles, because in these materials the concentration of aluminium is high and silica is low. Correlating the Bauxite Profiles with the probable geomorphical surfaces, following the altitude, it is not noticed any order, the profiles are distributed at random in the borders and in the inner area, in different levels of relief, where it is specially observed the occurrence of Bauxite Rim Profiles located in elevations of Plateau Profiles, and Reworked Profiles located over Rim Profiles, above 1,400 meters. The structural control observed in field, in literature and in the topographic maps shows zones of common faults, and 0it can associate this discontinuity of the Bauxite Profile with these movements. One of the clearest evidences are the drainage patterns, which are mainly controlled by basement structural alignments. Probably many movements have taken place before the formation of the Bauxite Profiles, however, a reactivation of the faults has ocurred, therefore it was verified that the faults cut the materials associated with Rim Profiles, Plateau Profiles and, specially in some instances, affect the levels of Reworked Profiles, indicating that the tectonic activity did not restrict only in molding the chart (with the climate) of the erosive processes which have affected the profiles ¿in situ¿, but it has advanced farther on the events of formation of the deposited laterite materials / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia

Cerca de 230 milhões de toneladas de bauxita são produzidas por ano e, destas, 60 milhões são provenientes de operações que beneficiam esta bauxita usando água como meio para separar as frações mais finas. Como consequência do beneficiamento, estima-se que mais de 25 milhões de toneladas de rejeito sejam dispostas todo ano. Estas frações têm grandes quantidades de caulinita, um argilomineral de difícil desaguamento. Estes sólidos estão tipicamente em uma suspensão com água a cerca de 15% de concentração em massa antes de operações de desaguamento. As formas de desaguamento variam, bem como as opções de disposição. Este texto discorre sobre opções de desaguamento como sedimentação natural, espessamento, filtragem e centrifugação. Também se discorre sobre alternativas de disposição. Estas são condicionadas pela concentração de sólidos do material a ser disposto e são a disposição hidráulica em diques ou reaterro na mina. Após a descrição de cada uma das alternativas, são feitas análises de combinações destas formas de desaguamento e disposição, além de uma avaliação do fluxo de caixa livre descontado acumulado para cada uma. Esta abordagem, feita para um caso específico, permite avaliar qual opção implica em menor despesa financeira para a operação. Foram feitas considerações para avaliar características não econômicas de cada uma das operações, como o consumo de água, área ocupada pelo depósito, perigos de cada opção e seus descomissionamentos. A opção que apontou menor desembolso no período da operação, bem como a minimização de perigos, é o desaguamento com centrífugas e disposição do material reaterrando áreas lavradas. / More than 230 million tonnes of bauxite are produced each year and, from these, nearly 60 million come from operations that use water to beneficiate the ore, separating the finer fractions. By reason of this mineral treatment, it is estimated that more than 25 million dry tonnes of reject are disposed each year. The finer fractions have high kaolinite concentrations, a challenging to dewater mineral. These solids are typically in a suspension with about 15% solids concentration in mass before any dewatering. Both the dewatering options and disposal possibilities may vary. This text discusses dewatering options such as natural settling, thickening, filtering and centrifugation. It also describes alternatives of disposing the material. These options depend on the water concentration and consist of hydraulic disposition or using the dewatered material as mine backfill. After describing each alternative, an analysis of possible combinations among those is made along with an accumulated discount free cash flow evaluation for each one. Considerations were made to evaluate non-economic characteristics of each operation including the water consumption, surface occupied, operational hazards, decommissioning and closure. The option that has shown the lowest cost during the life of the operation, simultaneously reducing operational hazards is dewatering with centrifuges and using the material as backfill in mined out areas.