Mineralogy and carbothermal reduction behaviour of vanadium-bearing titaniferous magnetite ore in Eastern India

Vanadium-beaxing titaniferous magnetite bands hosted by Precambrian gabbro-norite-anorthositic rocks or their metamorphic equivalents were discovered in some parts of Eastern Indian Shield, containing 48%-49% Fe （total）, 10%-25% TiO2, and 0.3%-2.20% V2O5 by mass. Mineralogical and petrological study, composition, and characterization of the vanadium-bearing titaniferous magnetite ore were carried out by scanning electron microscopy-energy dispersive X-ray （SEM-EDX）, wave length X-ray florescence （WDXRF）, inductively coupled plasma-atomic emission spectroscopy （ICP-AES）, X-ray diffraction （XRD）, etc. Chemical beneficiation for valuable metals, such as Fe, Ti, andV, was performed by reduction roasting. The direct and indirect reduction were investigated by mixing the lump ore with solid activated charcoal in a closed reactor and purging the reducing gas mixture in standard reducibility index apparatus at different temperatures and time intervals. The reduction roasting parameters were optimized. Finally, the reduced samples were crushed and upgraded by magnetic separation. The results show that, the maximum mass fractions of magnetic and nonmagnetic parts achieved axe 69.36% and 30.64%, respectively, which contain 10.6% TiO2 and 0.84% V205 in the magnetic part and 36.5% TiO2 and 0.22% V205 in the nonmagnetic part.

Oxidation behaviour and phase characterization of titaniferous magnetite ore of eastern India

Titaniferous magnetite ore is a kind of symbiotic complex ore which comprises ilmenite, magnetite, hercynite and magnesio-hercynite spinel minerals. The ore collected from eastern India was characterized by XRD, WDXRF, SEM and M？ssbauer spectroscopy. The oxidation behaviour of fine ore was investigated by TG-DTA analysis under oxygen atmosphere. Subsequent isothermal oxidation experiments were carried out under oxygen and air atmospheres, holding the samples for different periods of time at different temperatures from 873 K to 1473 K. It was observed that ilmenite phase transformed to hematite and titanium dioxide at lower temperature, whereas ferric-pseudobrookite phase was found at higher temperature. Direct reduction of oxidized sample-coke cylindrical briquettes was successfully achieved for phase transition from titaniferous magnetite to iron and titanium dioxide at 1473 K.

Microbial leaching of chromite overburden from Sukinda mines,Orissa,India using Aspergillus niger

Leaching of nickel and cobalt from two physical grades （S1, 125-190 μm, coarser and S3, 53-75 μm, finer） of chromite overburden was achieved by treating the overburden （2% pulp density） with 21-d culture filtrate of an Aspergillus niger strain grown in sucrose medium. Metal dissolution increases with ore roasting at 600℃ and decreasing particle size due to the alteration of microstructural properties involving the conversion of goethite to hematite and the increase in surface area and porosity as evident from X-ray diffraction （XRD）, thermogravimetry-differential thermal analysis （DT- TGA）, and field emission scanning electron microscopy （FESEM）. About 65% Ni and 59% Co were recovered from the roasted S3 ore employing bioleaching against 26.87% Ni and 31.3% Co using an equivalent amount of synthetic oxalic acid under identical conditions. The results suggest that other fungal metabolites in the culture filtrate played a positive role in the bioleaching process, making it an efficient green approach in Ni and Co recovery from lateritic chromite overburden.

The bacteriophage mu lysis system–A new mechanism of host lysis?

Bacteriophages are viruses that infect bacteria and can choose any one of the two alternative pathways for infection,i.e.,lysis or lysogeny.Phage lysis is one of the conventional biological processes required to spread infection from one bacterium to another.Our analysis suggests that in the paradigm bacteriophage Mu,six proteins might be involved in host cell lysis.Mu has a broad host range,and Mu-like phages were found in both Gram-negative and Gram-positive bacteria.An analysis of the genomes of Mu and Mu-like phages could be useful in elucidating the lysis mechanism in this group of phages.A detailed review of the various mechanisms of phage lysis and different proteins associated with the process will help researchers understand the phage biology and their life cycle in different bacteria.The recent increase in the number of multidrug-resistant(MDR)strains of bacteria and the usual long-term nature of new drug development has encouraged scientists to look for alternative strategies like phage therapy and the discovery of new lysis mechanisms.Understanding the lysis mechanism in the Mu-like phages could be exploited to develop alternative therapeutics to kill drug-resistant pathogenic bacteria.In this review article,we have analyzed the phage Mu-mediated host lysis system,which is unknown till now,and our analysis indicates a possibility of the existence of a new lysis mechanism operating in Mu.