Mining is an important industry, accounting for 6.9% of global GDP. However, global development promotes accelerated demand, resulting in the accumulation of hazardous waste in land, sea, and air environments. It reached 7 billion tonnes of mine tailings generated yearly worldwide, and 19 billion solid tailings will be accumulated by 2025. Adding to this, the legacy of environmental damage from abandoned mines is worrying; there are around 10,000 abandoned mines in Canada, 50,000 in Australia, and 6000 in South Africa, as well as 9500 coal mines in China, reaching 15,000 by 2050. In this scenario, restoration techniques from mining tailings have become increasingly discussed among scholars due to their potential to offer benefits towards reducing tailing levels, thereby reducing environmental pressure for the correct management and adding value to previously discarded waste. This review paper explores the available literature on the main techniques of mining tailing recycling and reuse and discusses leading technologies, including the benefits and limitations, as well as emerging prospects. The findings of this review serve as a supporting reference for decision makers concerning the related sustainability issues associated with mining, mineral processing, and solid waste management.

Mining is an important industry, accounting for 6.9% of global GDP. However, global development promotes accelerated demand, resulting in the accumulation of hazardous waste in land, sea, and air environments. It reached 7 billion tonnes of mine tailings generated yearly worldwide, and 19 billion solid tailings will be accumulated by 2025. Adding to this, the legacy of environmental damage from abandoned mines is worrying; in Canada there are around 10,000 abandoned mines, 50,000 in Australia, 6,000 in South Africa, and 9,500 coal mines in China, reaching 15,000 by 2050. In this scenario, restoration techniques from mining tailing have become increasingly discussed among scholars due to their potential to offer benefits towards reducing tailings levels, thereby reducing environmental pressure for the correct management and adding value to previously discarded waste. This review paper explores available literature on the main techniques of mining tailing recycling and reuse and discusses leading technologies, including the benefits and limitations, as well as emerging prospects. The findings of this review serve as a supporting reference for decision-makers concerning the related sustainability issues associated with mining, mineral processing, and solid waste management.

Solid waste management is a challenge for municipalities mainly due to the increasing generation of residues worldwide. Much waste still ends up in landfills, either as a final disposal sink, or as a temporary yet long-term storage prior to eventual landfill mining. Through degradation and infiltration processes, these materials threaten groundwater, soil and the environment, invariably causing expressive societal concern. Waste managers, environmentalists and regulators alike focus upon predicting how these complex geochemical systems will evolve over decades. Geochemical modeling and transport simulation are commonly used to support the design, operation or characterization of these dynamic systems. In this targeted critical review of the literature over the last two decades concerning geochemical modeling applications to waste disposal (including municipal, incineration residue, and industrial), we have attempted to provide an assessment of the current state of knowledge in this field, supported by a comprehensive list of modeling methodologies and data analyses, relevant for municipal solid waste (MSW) management systems. The information provided is meant to be useful for specialists when planning, implementing or adapting MSW systems.

A Educação Profissional e Tecnológica brasileira, nos últimos anos, principalmente de 2000 a 2016, vem passando por transformações oriundas de políticas públicas elaboradas visando a sua expansão e reestruturação. Frente a essas transformações, as escolas profissionalizantes são desafiadas a repensarem e ressignificarem a forma como mantêm um elo com a sociedade. Vários aspectos precisam ser observados e questionados no sentido de contribuir para a permanência e o sucesso dos discentes nas escolas profissionais. A evasão discente é um dos problemas enfrentados no ensino profissional, influenciada por diversos fatores que pesam na decisão do aluno em permanecer ou não no curso. Dentre esses elementos, destacam-se as práticas pedagógicas e sua relação com a aprendizagem e a motivação dos alunos, proporcionando um maior envolvimento com a instituição de ensino. Este trabalho teve como objetivo refletir sobre as práticas pedagógicas e a evasão discente no Curso Técnico de Eletromecânica do IFCE Campus Pecém. A referida pesquisa foi classificada, metodologicamente, como aplicada, com uma abordagem qualitativa, com características exploratórias e desenvolvida por meio de levantamento bibliográfico, estudos de casos e relatos de experiência. Os resultados obtidos possibilitaram uma melhor compreensão da ocorrência da evasão no referido curso, elencando as suas possíveis motivações. Foi verificada a grande importância das práticas pedagógicas para a permanência dos discentes no curso, pois que elas contribuem de forma significativa para o processo de ensino e aprendizagem.

Aços inoxidáveis duplex (AID) são caracterizados por apresentar interessante boas propriedades mecânicas e resistência à corrosão, possuindo um vasto campo de aplicação na indústria química e petroquímica. Geralmente, os reparos dos equipamentos ou estruturas são realizados por soldagem, sendo importante a seleção de parâmetros. É de suma importância a obtenção do teor adequado de ferrita no metal de solda, sendo que a variação da energia de soldagem pode influenciar de forma direta no percentual de ferrita. Logo, o objetivo deste trabalho é avaliar a influência da variação da energia de soldagem na microestrutura e na microdureza do metal de solda do AID. Foram realizadas soldagens de revestimento com sobreposição de duas camadas sobre o aço estrutural ASTM A516 Gr.60, utilizando eletrodo revestido AWS E2209-17. Três níveis de energia (15, 20 e 24 kJ/cm) foram empregados, variando-se a corrente e a velocidade de soldagem. Foi verificado que para os níveis de energia empregados não houve diferença significativa no percentual de ferrita, porém o primeiro cordão depositado apresentou maior teor de austenita em relação aos demais cordões. De forma geral, foi verificado que o primeiro cordão depositado obteve níveis maiores de microdureza. Todas as condições apresentaram microdurezas abaixo do valor crítico.

Plasma powder surfacing is one of the latest processes for application of coatings, with control of dilution as its main feature. Surfacing with superduplex stainless steels is an interesting option for the construction and repair of equipment for applications in a highly corrosive environment, allowing the desired characteristics to be achieved: corrosion resistance and good mechanical properties. The aim of this work is to assess the ferrite content in the weld metal and the mechanical characteristics via microhardness profiles in surfacing of C-Mn steel pipes with deposition of UNS S32760 by plasma powder surfacing. Welding operations were carried out on pipes with deposition of SDSS, employing three welding heat input levels, varying the welding speed or the welding current. Then the geometry was analysed, the ferrite content in the weld metal was quantified and the microhardness profile was recorded. Variation in welding heat input caused changes in weld bead geometry, with variation in the welding current producing the most significant changes. Increase in heat input caused decrease in ferrite content of the weld metal. Regarding microhardness, only the condition with a higher level of welding current gave sufficiently high levels of microhardness in the weld metal.