Behaviour of Compacted Filtered Iron Ore Tailings–Portland Cement Blends: New Brazilian Trend for Tailings Disposal by Stacking

Failures of tailings dams, primarily due to liquefaction, have occurred in Brazil in recent years. These events have prompted the Brazilian government to place restrictions on the construction of new dams, as iron ore tailings deposited behind upstream dams by spigotting have been shown to have low in situ densities and strengths and are prone to failure. This work proposes a new trend for tailings disposal: stacking compacted filtered ore tailings–Portland cement blends. As part of the proposal, it analyses the behaviour of compacted iron ore tailings–Portland cement blends, considering the use of small amounts of Portland cement under distinct compaction degrees. With the intention of evaluating the stress–strain–strength–durability behaviour of the blends, the following tests were carried out: unconfined compression tests; pulse velocity tests; wetting–drying tests; and standard drained triaxial compression tests with internal measurement of strains. This is the first study performed to determine the strength and initial shear stiffness evolution of iron ore tailings–Portland cement blends during their curing time, as well friction angle and cohesion intercept. This manuscript postulates an analysis of original experimental results centred on the porosity/cement index (η/Civ). This index can help select the cement quantity and density for important design parameters of compacted iron ore tailings–cement blends required in geotechnical engineering projects such as the proposed compacted filtered iron ore tailings–cement blends stacking.

Numerical Investigation of Iron Ore Tailings Filled Epoxy Composite as Heat Resistant Material

The thermal properties of epoxy composites reinforced with iron ore tailings were used to investigate the thermal performance of the composite as heat resistant material. Thermal properties are important parameters for determining the behaviour and appropriate applications of materials. This paper focuses on investigating the thermal performance of epoxy composite reinforced with iron ore tailings (IOT) of particles sizes 150 µm, 10% reinforced. The thermal properties of the selected epoxy-IOT composite were specific heat capacity – 2352 J/kg-K, thermal resistivity – 4.788 °C-m/W, thermal diffusivity – 0.089 mm2/s and Thermal conductivity – 0.209 W/m-K. The selected epoxy-IOT composite was numerically compared with an existing material (gypsum board) of the following thermal properties: specific heat capacity – 1090 J/kg-K, thermal resistivity – 3.87°C-m/W, thermal diffusivity – 0.333 mm2/s and Thermal conductivity – 0.258 W/m-K. The numerical analysis was done using Autodesk Fusion360, by modelling the materials as slabs.The heat transfer process of the composite and the prediction of the heat resistance capability were explained by comparing the results with an existing material (gypsum plasterboard) using their mechanical and thermal properties.The numerical results indicated that the epoxy-IOT composite has lower minimum temperature and thermal stress compared with the existing material (gypsum board), which implies that epoxy-IOT composite when used as a heat insulator will resist heat and sustain thermal stress better than the gypsum board of the same geometry under the same conditions. In conclusion, an epoxy-IOT composite of appropriate mixing ratio and geometry can be comfortable use as heat resistant materials. Keywords— Epoxy-IOT, Numerical Analysis, Temperature Distribution, Thermal Performance, Thermal Stress

Os Krenak e o desastre da mineração no Rio Doce

Em 5 de novembro de 2015, a barragem de rejeitos de minério de ferro conhecida como Barragem de Fundão, de propriedade da Samarco Mining Inc. Company, uma joint venture envolvendo a Vale S. A. e a BHP Billiton Brasil Ltda, desabou no município de Mariana, Minas Gerais. Cerca de 50 milhões de metros cúbicos de resíduos de mineração foram lançados no Rio Doce e transportados por mais de 600 km até sua foz, no Oceano Atlântico. Entre as muitas comunidades profundamente afetadas estão as do povo indígena Krenak, que habitam a margem esquerda do Rio Doce. Com base na descrição histórica e etno­gráfica dos Krenak e dos conflitos que vivenciaram em seu território ao longo dos anos, o artigo analisa como esse povo foi afetado pelo desastre da mineração do rio Doce. Seis anos depois, o desastre preva­lece como um processo constantemente renovado na vida cotidiana das privações a que todos os grupos afetados foram submetidos. Para o Povo Krenak, o Watu é muito mais do que um rio que proporciona alimentação, lazer, água para os animais e irrigação, enfim, um recurso natural para a sobrevivência. É um parente com quem estabelecem relações. Um familiar que acolhe, aconselha, protege e contribui para a construção da pessoa Krenak. Sua perda, portanto, coloca um desafio ao sistema de justiça ocidental: o reconhecimento de direitos que podem ser formulados a partir de outros sistemas de valoração, basea­dos em cosmovisões e ontologias que questionam o alcance das formas de comensurabilidade e tradução impostas pelo mundo ocidental. Palavras-chave: Mineração; Desastres no Rio Doce; Povo indígena Krenak; Territórios Indígenas; Conflitos Ambientais. Abstract On November 5, 2015, the iron ore tailings dam known as the Fundão Dam, owned by the Samarco Mining Inc. Company, a joint venture involving Vale S. A. and BHP Billiton Brasil Ltda, collapsed in the municipality of Mariana, Minas Gerais. Around 50 million cubic metres of mining waste were released into the Rio Doce and carried for over 600 km to its mouth on the Atlantic Ocean. Among many communities deeply affected are those of the Krenak indigenous people who inhabit the left margins of the Doce River. Based on historical and ethnographic description of the Krenak and the conflicts they have experienced in their territory over the years, the chapter analysis how this people found themselves affected by the Doce River mining disaster. Six years on, the disaster prevails as a process constantly renewed in the everyday life of privations to which all the affected groups have been subjected. For the Krenak people, the Watu is much more than a river that provides food, leisure, watering for animals and irrigation, a natural resource, in short, for survival. It is a relative with whom they establish relationships. A relative that welcomes, counsels, protects, and contributes to the construction of the Krenak person. Their loss, thus, poses a challenge to the Western justice system: the recognition of rights that can be formulated from other systems of valuation, based on cosmovisions and ontologies that question the reach of the forms of commensurability and translation imposed by the Western world. Keywords: Mining; Doce River disaster; The Krenak people; Indigenous territory; Environmental conflict. El pueblo indígena Krenak y el desastre minero del Río Doce Resumen El 5 de noviembre de 2015, la presa de relaves de mineral de hierro conocida como Fundão, propiedad de Samarco Mining Inc. Company, una empresa conjunta que involucra a Vale SA y BHP Billiton Brasil Ltda, colapsó en el municipio de Mariana, Minas Gerais. Cerca de 50 millones de metros cúbicos de desechos mineros se vertieron en el Río Doce y se transportaron más de 600 km hasta su desembocadura en el Océano Atlántico. Entre las muchas comunidades profundamente afectadas se encuentran las del pueblo indígena Krenak, que habitan en la margen izquierda del Río Doce. A partir de la descripción histórica y etnográfica de los Krenak y los conflictos que vivieron en su territorio a lo largo de los años, el artículo analiza cómo estas personas fueron afectadas por el desastre minero del río Doce. Seis años después, el desastre prevalece como un proceso que se renueva constantemente en la vida cotidiana a partir de las privaciones a las que fueron sometidos todos los grupos afectados. Para la gente de Krenak, el Watu es mucho más que un río que proporciona alimento, ocio, agua para los animales e irrigación, un recurso natural para la supervivencia. Es un familiar con el que establecen relaciones. Un familiar que acoge, ase­sora, protege y contribuye a la construcción de la persona Krenak. Su pérdida, por tanto, plantea un desa­fío para la justicia occidental: el reconocimiento de derechos que pueden ser formulados desde otros sistemas de valoración, basados en cosmovisiones y ontologías que cuestionan el alcance de las formas de conmensurabilidad y traducción impuestas por el mundo occidental. Palabras clave: Minería; Desastre del Río Doce; Indígenas Krenak; Territorios indígenas; Conflictos am­bientales.

Study on Properties of Concrete with Iron Ore Tailing and Glass Waste

The aim of this research is to test the characteristics of concrete by substitute fine aggregate with iron ore tailings and partial glass powder as in the place of cement. Concrete with waste products such as glass powder and iron ore tailings offer technical, economic and environmental advantages. In this experimental investigation, glass powder is replaced with cement by 10%, 20% and 30% and iron ore tailings with fine aggregates by 30% which is the optimum percentage. To study the role of glass powder and iron ore tailings combination in concrete. The properties such compressive strength, flexural strength, tensile strength and also durability parameters likely water absorption investigation for M40 concrete is carried out with different percentages of glass powder by keeping the iron ore tailings percentage constant. At 30% glass powder substitution as cement and sand with IOT increases concrete effectiveness. The concrete with 10% glass powder & 30% iron ore tailings showed a higher strength compared to the conventional mix for 28 days. Concrete mix containing 10% GP and 30% IOT showed higher flexural strength of 5.05 MPa for 28 days. Splitting tensile strength value is also increasing i. e for 10% glass powder and 30% IOT, obtained splitting tensile strength was 4.48 MPa and modulus of elasticity value was has also increased. Water absorption experiment consequences results that water absorption decreases with an increase in GP percentage. The concrete workability tends to decrease when with glass powder content increase. Concrete containing 10% glass powder and 30% IOT showed maximum strength and it is considered as the optimum dosage.