19341 research outputs found
Sort by
Solucionando instabilidades nos processos de peneiramento e britagem na indústria da mineração por meio de estratégia de controle override.
No full textPrograma de Pós-Graduação em Instrumentação, Controle e Automação de Processos de Mineração. Departamento de Engenharia de Controle e Automação, Escola de Minas, Universidade Federal de Ouro Preto.O processamento de minério de ferro à umidade natural representa um desafio substan- cial na indústria de mineração. Melhorar a produtividade dos circuitos, otimizar o desempenho e prolongar a vida útil dos equipamentos são prioridades cruciais. Nesse contexto, a disciplina de otimização e controle desempenha um papel vital na automatização dos processos, com o propósito de maximizar a eficiência e promover a sustentabilidade das operações de mineração. O desafio consiste em integrar de forma inovadora e eficaz as disciplinas de automação com o tratamento de minério, a fim de mitigar as instabilidades no processo. Essas instabilidades resultam em frequentes intemipções no processo de curta duração, porém numerosas, transfor- mando, em diversos momentos, um processo contínuo em batelada. Essas breves interrupções impactam negativamente a eficiência das operações. Assim, este trabalho apresenta soluções desenvolvidas em estratégia de controle override em duas operações unitárias distintas: penei- ramento e britagem. As melhorias implementadas na etapa de peneiramento, são baseadas em uma análise de correlação identificada entre a corrente de acionamento da peneira e as carac- terísticas do minério que resultou em redução de 67% das paradas por sobrecargas e 71% das paradas por intertravamentos de processo. Também será apresentada uma nova estratégia de controle realizada para etapa de britagem que reduziu em 839c as microparadas operacionais através de um controleThe processing of iron ore with natural moisture content represents a substantial chal-
lenge in the mining industry. Enhancing circuit productivity, optimizing performance, and ex-
tending equipment lifespan are crucial priorities. In this context, the discipline of optimization
and control plays a vital role in automating processes with the aim of maximizing efficiency and
promoting the sustainability of mining operations. The challenge lies in innovatively and ef-
fectively integrating automation disciplines with ore treatment to mitigate process instabilities.
These instabilities lead to frequent, albeit brief, interruptions in the process, at various times,
transforming a continuous process into a batch process. These brief interruptions have a neg-
ative impact on operational efficiency. Thus, this work presents solutions developed through
an override control strategy in two distinct unit operations: screening and crushing. The im-
provements implemented in the screening stage are based on an identified correlation analysis
between the sieve drive current and ore characteristics, resulting in a 67% reduction in stop-
pages due to overloads and a 71% reduction in process interlock stoppages. Additionally, a
new control strategy will be presented for the crushing stage, which reduced operational micro-
stoppages by 83% through silo level override control, without compromising the crusher cham-
ber level control. All of these solutions have led to process stability, resulting in increased
efficiency, productivity, and safety of the assets involved
Importance of hydrogen in the mining industry as a renewable energy source.
No full textIn mining, the system of operation relies on equipment that consumes large amounts of energy. In mine operations, diesel-powered equipment is widely used due to its flexibility, loading capacity, and adaptability to various terrain conditions. However, presents high diesel oil consumption and a high emission rate of greenhouse gases. This paper offers a view of the effect of hydrogen on diesel engines in the search for renewable energy alternatives that are in tune with the reduction of the environmental impact arising from the use of petroleum-derived fuels. It is followed by a discussion of energy consumption in mining. Introduces hydrogen production technologies, the advantages of using them in controlled quantities, and the challenges in production, storage, and supply costs. Highlight the “green hydrogen”, carbon-free, an emerging alternative in the decarbonization of mines.Na mineração, o sistema de operação depende de equipamentos que consomem grandes quantidades de energia. Nas operações mineiras, os equipamentos a diesel são amplamente empregados devido à sua flexibilidade, capacidade de carga e adaptabilidade a várias condições de terreno. Entretanto, apresentam alto consumo de óleo diesel e alta taxa de emissão de gases de efeito estufa. Este artigo oferece uma visão do efeito do hidrogênio sobre os motores diesel na busca de alternativas de energia renovável que estejam em sintonia com a redução do impacto ambiental
decorrente do uso de combustíveis derivados do petróleo. É seguido por uma discussão do consumo de energia na mineração. Apresenta as tecnologias de produção do hidrogênio, as vantagens em utilizá-los em quantidades controladas e os desafios de produção, armazenamento e custos de fornecimento. Destaca-se o hidrogênio verde, livre de carbono, uma alternativa emergente na descarbonização das minas
Characterization of magnetic tailings from phosphate-ore processing in Alto Paranaíba.
No full textThe characterization studies of tailings from mining are crucial for the development of its reuse
processes and the reduction of impacts caused by its conditioning on the earth’s surface. This study
characterizes the magnetic tailings from phosphate-rock processing using X-ray diffraction, X-ray
fluorescence spectrometry and quantitative electron microscopy techniques. Samples were obtained
from the magnetic tailings deposit of a mining company in the Alto Paranaíba region, Minas Gerais.
The tailings are mainly composed of hematite/magnetite (74.92%), ilmenite (8.91%), fluorapatite
(8.8%), anatase (3.07%), calcite (1.67%), goethite (1.62%), and quartz (1.02%). The particle size of the
tailings is smaller than that specified for the production of sinter feed. The hematite/magnetite phase
is strongly associated with ilmenite and fluorapatite. New stages of comminution and separation are
needed due to the low degree of liberation of these minerals for a possible reuse of the components
Los derechos sexuales y reproductivos de las mujeres en Brasil en la perspectiva del feminismo decolonial.
No full textObjetivo: analisar os direitos sexuais e reprodutivos da mulher no Brasil na perspectiva do feminismo
decolonial. Metodologia: tratou-se de pesquisa teórico-dogmática que, com base nas normas jurídicas,
objetivou esboçar os direitos sexuais e reprodutivos das mulheres e descortinar esses direitos, na
constatação de interseccionalidades como entraves ao reconhecimento e exercício deles na perspectiva
decolonial. Resultados: verificou-se que as normas jurídicas, de forma hegemônica, não são
suficientes, eis que questões socioeconômicas e jurídicas acabam por impedir sua efetivação a todas
as mulheres. Conclusão: fatores interseccionais e de diversidade impedem o exercício dos direitos
sexuais e reprodutivos das mulheres no Brasil, de forma que as normas jurídicas não são suficientes
para a garantia dos direitos.Objective: to analyze the sexual and reproductive rights of women in Brazil from the perspective of
decolonial feminism. Methods: it was a theoretical-dogmatic investigation that aimed to outline, based
on legal norms, the sexual and reproductive rights of women and to show these rights, considering
intersections, as obstacles to the recognition and exercise of these rights in a decolonial perspective.
Results: legal norms were found to be inadequate in hegemonic ways, as socioeconomic and legal
issues prevent their implementation for all women. Conclusion: intersectional and diversity factors
prevent the exercise of women's sexual and reproductive rights in Brazil, making legal norms
insufficient to guarantee rights
Use of hollow fibre membrane contactors to remove dissolved gases from effluents of UASB reactors treating sewage after its conditioning with dynamic membrane filtration.
No full textDissolved gases in the effluent of anaerobic reactors, such as dissolved methane (D-CH4) and sulphide (S2− ), are a
drawback for anaerobic-based sewage treatment plants. Hollow fibre membrane contactors (HFMCs) have been
tested for the removal of these compounds, and this paper evaluated a novel configuration with pressurised
dynamic membrane modules (PDMMs) for conditioning an anaerobic effluent (from UASB reactor fed with
sewage) as a means to reduce HFMCs clogging and fouling. Three PDMMs were used for the anaerobic effluent
conditioning before two types of HFMCs (dense and microporous membranes). An automated backwash with a
tap water cleaning protocol complemented with a chemical cleaning protocol (NaOH and citric acid) was applied
for fouling control. The microporous HFMC could not maintain a stable performance (D-CH4 and S2− removal
drop of 30 % and 40 %, respectively, in 10 days of operation), arguably due to membrane wetting, meanwhile the
dense HFMC showed a more stable behaviour (removal efficiencies close to 100 % and 90 % for S2− and D-CH4,
respectively in >30 days). The water backwash removed an important fraction of the entrapped organic solids.
Meanwhile, the NaOH cleaning was efficient in removing inorganic compounds. Citric acid contributed to the
removal of calcium and phosphate
Multispecies scenes : artistic implications between plants, non-human animals and humans.
No full textNo presente editorial trazemos as inquietações práticas e conceituais que nos inspiraram a propor a temática do presente dossiê, bem como apresentamos individualmente cada ensaio ou artigo que dá corpo ao presente volume, ajudando-nos a refletir sobre a urgente temática ecológica e o necessário repensamento, também poético, sobre as relações multiespécies.In this editorial we bring the practical and conceptual concerns that inspired us to propose the theme of this dossier, as well as individually presenting each essay or article that gives shape to this volume, helping us to reflect on the urgent ecological theme and the necessary rethinking, also poetic, about multispecies relationships
Soluções solitônicas em condensados de Bose-Einstein.
No full textPrograma de Pós-Graduação em Ciências – Física de Materiais. Departamento de Física, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto.O condensado de Bose-Einstein é formado quando um gás bosônico é resfriado a uma tem-
peratura próxima do zero absoluto. Quando isso ocorre, as propriedades quânticas que são
microscópicas tornam-se macroscópicas, facilitando seu estudo. Nesta dissertação, estudare-
mos ondas de matéria, no contexto de uma representação não-linear para os condensados de
Bose-Einstein sendo submetidos a um potencial Kapitza de armadilha, que é um análogo quân-
tico do pêndulo clássico invertido de Kapitza. Neste potencial foi adicionado um termo linear
que, de certa forma, pode ser associado à interação gravitacional. Para isso, utilizaremos a
equação não-linear de Schrödinger dependente do tempo, também conhecida como equação
de Gross-Pitaevskii. Para encontrar as soluções analíticas, utilizaremos o método da função
tangente hiperbólica estendida, conduzindo a soluções solitônicas. Por meio dessas soluções é
possível analisar o impacto dos parâmetros do potencial Kapitza e do campo gravitacional na
dinâmica solitônica do condensado.Bose-Einstein condensate is formed when bosonic gas is cooled to a temperature close to ab-
solute zero. When this occurs, quantum properties that are microscopic become macroscopic,
facilitating their study. In this dissertation, we will study matter waves, in the context of a non-
linear representation for Bose-Einstein condensates being subjected to a trap Kapitza potential,
which is a quantum analogue of the classical Kapitza inverted pendulum. In this potential a
linear term was added that, in a certain way, can be associated with the gravitational interaction.
For this, we will use the nonlinear time-dependent Schrödinger equation, also known as the
Gross-Pitaevskii equation. To find the analytical solutions, we will use the extended hyperbolic
tangent function method, leading to solitonic solutions. Through these solutions it is possible
to analyze the impact of the parameters of the Kapitza potential and the gravitational field on
the solitonic dynamics of the condensate
Investigation of the presence of metallic phases in Brazilian tin-slags.
No full textThe supply chain of Sn presents social and environmental risks that could threaten the availability of cassiterite, while secondary materials, such as tin-slags, stand as an alter native source for smelters. In this context, this work investigated the presence of occluded metallic phases in Brazilian tin-slags. Chemical analyses of different slags revealed that this fact could be related to high ZrO2 levels, which was also supported by different ther modynamic studies. It was indicated that minor additions of CaO could diminish the melting temperature of these slags, contributing towards the precipitation of metallic prills. Smelting experiments were performed between 1773-1573K with a tin-slag concentrate using limestone as a fluxing agent. It was verified that metallic prills were
mostly precipitated in the bottom of the crucible above 1673K. However, at 1573K, a mixture of metallic and oxidized phases was obtained, indicating that low working tem peratures lead to losses of Sn in the final slag as metallic inclusions. Further additions of limestone improved the coalescence but did not allow efficient precipitation of thes metallic prills. Temperature measurements were performed in a 150 kVA EAF during slag processing, and it was verified that tapping of metal/slag occurred partially below 1573K, justifying the presence of metallic prills in the studied slags. Therefore, an optimization of the process relies both on the dilution of ZrO2 content by a controlled addition of fluxing agents, as well as by an increase in working temperatures. Alternatively, magnetic sepa ration can be used to recover occluded metallic particles from final slags
Otimização do consumo energético de um circuito de britagem de uma mineradora via Sim-heuristic.
No full textPrograma de Pós-Graduação em Engenharia de Produção. Departamento de Engenharia de Produção, Instituto de Ciências Exatas e Aplicadas, Universidade Federal de Ouro Preto.Esta dissertação tem como foco a proposição de uma Sim-heuristic para a resolução do problema
de minimização do consumo energético de uma planta de britagem de uma mineradora, para
um dado volume produtivo. A metodologia proposta se baseia na combinação da metaheurística
ILS (implementada em Python) com um simulador (codificado no Octave) que calcula o volume
de produção da planta de britagem em função dos equipamentos em operação, para diferentes
padrões de granulometria de minério. Para auxiliar o modelo de simulação, são propostos
também diferentes equações de regressão linear múltipla (metamodelos), capazes de estimar
o volume de produção com um R
2
superior a 75% em um tempo computacional reduzido.
Os resultados computacionais mostram que é possível reduzir significativamente o consumo
energético necessário para a produção de um dado volume produtivo em diferentes cenários de
operação.This dissertation focuses on the proposition of a Sim-heuristic to solve the problem of minimizing
the energy consumption of a crushing plant of a mining company for a given production volume.
The proposed methodology combines the ILS metaheuristic (implemented in Python) with a
simulator (coded in Octave) that calculates the crushing plant production volume as a function
of the equipment in operation for different ore granulometry patterns. To assist the simulation
model, different multiple linear regression equations (metamodels) are also proposed, capable of
estimating the production volume with a R
2 greater than 75% in a reduced computational time.
The computational results show that it is possible to significantly reduce the energy consumption
required to produce a given production volume in different operating scenarios
Digital supply chain : roadmap development and application based on Industry 4.0 principles.
No full textThe present study proposes technological routes that integrate Industry 4.0 (I4.0) principles, architectures, and technologies, in favor of a Digital Supply Chain (DSC). This study was accomplished in a company in the steel industry that is adopting I4.0 technologies to promote improvements in its supply chain management process. Interviews and focal group were conducted with twelve professionals from the supply and intelligence department. Then, it was possible to trace the technological roadmap that helps managers to implement these I4.0 technologies in their processes