Development of Fluxed Iron Oxide Pellets for Steel Making Utilizing Waste Materials

Lump lime is conventionally used as a flux material in steel making. However, use of burnt lump lime often creates problem in operation due to its high melting point, poor dissolution property, fine generation tendency and hygroscopic nature. Lime in combination with iron oxide may form a low melting oxidizing slag and makes the refining process faster. In this context, NML has developed a novel process of making fluxed pellet utilizing waste materials from steel plant without using any binder and without firing. The developed pellet shows very good cold crushing strength (30Kg/pellet), drop impact strength (150) and tumbler index (98%). The high temperature properties of the pellets like thermal shock resistance, melting point (1180oC) and dissolution time (30-60 sec) in molten bath are also found to be excellent. Performance of pellets has been assessed in a simulated oxygen bottom blown process in laboratory scale. Very fast decarburization and dephosphorization, improved metallic yield and decrease in oxygen consumption with controlled foaming are observed. Overall, in the present study the lime-fluxed iron ore pellets, developed in a binder-less room temperature process utilizing waste materials of steel plant are found to possess good cold handling and thermal properties, and favorable melting and refining characteristics, to warrant their application as a partial/complete substitute of the traditional scrap-lime combination in basic oxygen steel making or faster refining in steel making process

Nanoparticle assembly: a perspective and some unanswered questions

In early 2016, the Royal Society of Chemistry arranged a meeting on the topic 'Nanoparticle Assemblies: from Fundamentals to Applications' which was hosted at IIT-Bombay, Mumbai. The meeting brought several leading nanoscience and nanotechnology researchers to India and is only the second Faraday Discussions meeting to have been held in the country. The papers presented at the meeting and the resulting active discussions have been summarized in a Faraday Discussion issue(1). The broad range of topics discussed at the meeting led to an understanding on where we stand in the field of nanoparticle assembly, and also enunciated some of the outstanding fundamental and practical issues that remain to be resolved before these ideas can be applied to practical situations. Driven by these ideas, here we focus on four topics/questions: (i) Can we achieve function-driven design of nanoparticle assemblies? (ii) What is the minimal information needed to build a desired assembly? (iii) How complex a structure can one build? How can one make it responsive? What are the relative roles of equilibrium versus dynamics in the assembly process, and are we at a point where we can now pursue active assembly as a viable mode for creating complex assemblies? (iv) What are the applications that are being targeted and what are the barriers to implementation? In this perspective, we do not present an exhaustive survey of the vast literature in this area, but indicate overarching themes/questions that require immediate attention, largely based on the discussions at the Mumbai meeting.open

Spin dynamics from time-dependent density functional perturbation theory

We present a new method to model spin-wave excitations in magnetic solids, based on the Liouville-Lanczos approach to time-dependent density functional perturbation theory. This method avoids computationally expensive sums over empty states and naturally deals with the coupling between spin and charge fluctuations, without ever explicitly computing charge-density susceptibilities. Spin-wave excitations are obtained with one Lanczos chain per magnon wave-number and polarization, avoiding the solution of the linear-response problem for every individual value of frequency, as other state-of-the-art approaches do. Our method is validated by computing magnon dispersions in bulk Fe and Ni, resulting in agreement with previous theoretical studies in both cases, and with experiment in the case of Fe. The disagreement in the case of Ni is also comparable with that of previous computations

Globally invariant metabolism but density-diversity mismatch in springtails.

Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning

Global fine-resolution data on springtail abundance and community structure

Springtails (Collembola) inhabit soils from the Arctic to the Antarctic and comprise an estimated ~32% of all terrestrial arthropods on Earth. Here, we present a global, spatially-explicit database on springtail communities that includes 249,912 occurrences from 44,999 samples and 2,990 sites. These data are mainly raw sample-level records at the species level collected predominantly from private archives of the authors that were quality-controlled and taxonomically-standardised. Despite covering all continents, most of the sample-level data come from the European continent (82.5% of all samples) and represent four habitats: woodlands (57.4%), grasslands (14.0%), agrosystems (13.7%) and scrublands (9.0%). We included sampling by soil layers, and across seasons and years, representing temporal and spatial within-site variation in springtail communities. We also provided data use and sharing guidelines and R code to facilitate the use of the database by other researchers. This data paper describes a static version of the database at the publication date, but the database will be further expanded to include underrepresented regions and linked with trait data.</p

Surface plasmon resonance in nanocrystalline silver in a ZnO matrix

Silver nanoparticles embedded in ZnO matrix were deposited onto fused silica substrates using high pressure ($\sim$40 Pa) d.c. sputtering techniques. The particle size in the films was tailored by varying the system pressure and substrate temperature, while the metal volume fraction was controlled by adjusting the relative time of sputtering of the targets. Blue-shift of the surface plasmon resonance peak was observed with the reduction in size and volume fraction of metal particles. A surface plasmon peak in the absorption spectra was found to be absent in the films with particle size and metal concentration below a critical value. A sharp absorption edge in the absorbance spectra within the UV-VIS range indicated semiconducting behavior of the ultrafine silver particles. Films deposited at lower substrate temperature showed a narrow distribution of nanoparticles, nearly spherical in shape. Increase in substrate temperature resulted in a non-uniform size and shape in the films due to the agglomeration of the nanoparticles. These size and shape distributions have a profound effect on the optical absorbance spectra and result in a broad and asymmetric surface plasmon band. A shape distribution introduced in the Maxwell-Garnett or Bruggeman effective medium theory was found to give a reasonable description of the experimentally observed optical absorption spectra

Synthesis of both enantiomers of 1-phenylethane-1,2-diol via chirality transfer from bile acid derivatives

Both enantiomers of 1-phenylethane-1,2-diol were synthesized with good to excellent enantioselectivities via selective reduction of the phenylglyoxalates derived from bile acids, followed by reductive cleavage

Refining of hot metal utilizing fluxed iron oxide pellets

Fluxed iron-oxide pellets were prepared using waste iron oxide fines and lime fines and subsequently treated with industrial waste through room temperature binder less process that developed its handling strength (CCS 30 kg/pellet). It has the potential to partially replace scrap and lump lime as BOF charge material. In order to assess the suitability of pellets in refining, performance of the treated pellets in the refining of hot metal was investigated in a laboratory-scale, bottom blowing ladle, lined with magnesite. The hot metal was prepared by melting pig iron chips in an induction furnace, which was subsequently transferred to the bottom blowing ladle. Refining was carried out with the following three flux combinations, viz. i) Heats with lime alone as flux ii) Heats with treated pellets plus additional lime as flux, iii) Heat with iron ore plus lime as flux. Pellets containing 30% lime in their base mixtures were used in this performance study. Parameters like oxygen flow rate, initial temperature and composition of hot metal, slag basicity, etc. were kept constant in all heats as far as practicable. The progress of the removal of C, P, Si, and Mn was studied by collecting metal samples from the refining bath at different blowing stages for chemical analysis. C, P and Mn removals were observed to be faster with the use of pellets than with the other two combinations (combinations-i. and iii.). It was also found that the pellet addition in the proportion of 8% of hot metal brought about a greater removal rate of carbon than that in higher (10%) or lowers (5%) proportions. the metallic yield was found to improve by 1.4%, in comparison with the use of lime alone as flux. Also, there was a remarkable saving in oxygen consumption. This study mainly emphasizes on the comparative heat and mass balance in different flux conditions and analysis of thermodynamic and kinetic aspect of comparative C, P, Si and Mn removal in aforementioned conditions