Beneficiation of indian iron ore lumps and fines by using underbed air–pulsated BATAC jigs

After setting a target of 100 MT/yr of Steel by 2012, Indian Steelmakers and Iron Ore producers are already struggling due to the depleted grade of Iron Ore available in India. The main impurities dominating the Indian Iron Ores are SiO2 and Al2O3 which should be reduced with an economical method of Beneficiation. Jigs are the earliest type of process equipments employed in mineral separation but the newly developed under bed pulsated BATAC Jig has considerable advantages over its counterparts. There are various types of BATAC Jigs available for Lump and Fines such as Lump Ore (2 products/3 products) Jig and Fine Ore (2- product) Jig. A South African iron ore producer recently commissioned a 10 Mtpa-capacity greenfield Iron Ore beneficiation plant with 2 Lump Ore BATAC Jigs and 2 Fine Ore with a combined capacity of 1240 tph at Assmang Khumani Iron Ore Mine in Northern Cape, South Africa. The Concentrate contains a Fe grade of > 66%. A further capacity expansion project to 16 Mtpa product is currently underway using 3 more BATAC jigs. The first large scale Iron Ore Jig beneficiation plant in India was commissioned in 2006 at Noamundi in the state of Jharkhand. Tata Steel is already operating a 300 tph Fine Ore BATAC Jig Iron Ore Plant there. Patnaik Minerals also followed the pattern and started constructing 100 tph Fine Ore Jigging Plant at Joda, Jharkhand. There are different combinations possible in which unit operations can be arranged which include Jigs as the heart of the beneficiation process. These various types of flow sheets provided this beneficiation method with an advantage over other unit operations. Lessons learned and best practices regarding equipment selection and operation acquired during the last 10 years are summarized to define potential BATAC Jig applications in Iron Ore. Finally, field experiences and results are analyzed to establish the best strategy to fit specific Indian Iron Ore conditions

Queer In AI: A Case Study in Community-Led Participatory AI

We present Queer in AI as a case study for community-led participatory design in AI. We examine how participatory design and intersectional tenets started and shaped this community's programs over the years. We discuss different challenges that emerged in the process, look at ways this organization has fallen short of operationalizing participatory and intersectional principles, and then assess the organization's impact. Queer in AI provides important lessons and insights for practitioners and theorists of participatory methods broadly through its rejection of hierarchy in favor of decentralization, success at building aid and programs by and for the queer community, and effort to change actors and institutions outside of the queer community. Finally, we theorize how communities like Queer in AI contribute to the participatory design in AI more broadly by fostering cultures of participation in AI, welcoming and empowering marginalized participants, critiquing poor or exploitative participatory practices, and bringing participation to institutions outside of individual research projects. Queer in AI's work serves as a case study of grassroots activism and participatory methods within AI, demonstrating the potential of community-led participatory methods and intersectional praxis, while also providing challenges, case studies, and nuanced insights to researchers developing and using participatory methods.Comment: To appear at FAccT 202

Pinhole-seeded lateral epitaxy and exfoliation of GaSb films on graphene-terminated surfaces

Remote epitaxy represents a promising method for the synthesis of thin films on lattice-mismatched substrates, but its atomic-scale mechanisms are still unclear. Here, the authors demonstrate the growth of exfoliatable GaSb films on graphene-terminated GaSb (001) via seeded lateral epitaxy, showing that pinhole defects in graphene serve as selective nucleation sites

Bottom-up synthesis of mesoscale nanomeshes of graphene nanoribbons on germanium

The synthesis of functional graphene nanostructures on Ge(001) provides an attractive route toward integrating graphene-based electronic devices onto complementary metal oxide semiconductor-compatible platforms. In this study, we leverage the phenomenon of the anisotropic growth of graphene nanoribbons from rationally placed graphene nanoseeds and their rotational self-alignment during chemical vapor deposition to synthesize mesoscale graphene nanomeshes over areas spanning several hundred square micrometers. Lithographically patterned nanoseeds are defined on a Ge(001) surface at pitches ranging from 50 to 100 nm, which serve as starting sites for subsequent nanoribbon growth. Rotational self-alignment of the nanoseeds followed by anisotropic growth kinetics causes the resulting nanoribbons to be oriented along each of the equivalent, orthogonal Ge⟨110⟩ directions with equal probability. As the nanoribbons grow, they fuse, creating a continuous nanomesh. In contrast to nanomesh synthesis via top-down approaches, this technique yields nanomeshes with atomically faceted edges and covalently bonded junctions, which are important for maximizing charge transport properties. Additionally, we simulate the electrical characteristics of nanomeshes synthesized from different initial nanoseed-sizes, size-polydispersities, pitches, and device channel lengths to identify a parameter-space for acceptable on/off ratios and on-conductance in semiconductor electronics. The simulations show that decreasing seed diameter and pitch are critical to increasing nanomesh on/off ratio and on-conductance, respectively. With further refinements in lithography, nanomeshes obtained via seeded synthesis and anisotropic growth are likely to have superior electronic properties with tremendous potential in a multitude of applications, such as radio frequency communications, sensing, thin-film electronics, and plasmonics