NML's Activities on Non-ferrous Metals Extraction

India is not well endowed with high grade deposits of ores and minerals of nonferrous metals except bauxite ore of aluminium and beach sand containing titanium, zirconium, and rare earth metals. Hence, the National Metallurgical Laboratory, Jamshedpur, which was first laboratory in the country established to cater the need for developing metal extraction processes, had to concentrate on the beneficia-tion of available lean grade ores of non-ferrous metals and the extraction of valuable metals from the concentra-tes, industrial wastes and secondary resources. This paper briefly mentions the technologies developed, infrastruc-ture and facilities established and the current activities in the field of non-ferrous metal extraction in the labora-tory

Cephem Potentiation by Inactivation of Nonessential Genes Involved in Cell Wall Biogenesis of ß-Lactamase-Producing Escherichia coli

Reversal of antimicrobial resistance is an appealing and largely unexplored strategy in drug discovery. The objective of this study was to identify potential targets for “helper” drugs reversing cephem resistance in Escherichia coli strains producing β-lactamases. A CMY-2-encoding plasmid was transferred by conjugation to seven isogenic deletion mutants exhibiting cephem hypersusceptibility. The effect of each mutation was evaluated by comparing the MICs in the wild type and the mutant harboring the same plasmid. Mutation of two genes encoding proteins involved in cell wall biosynthesis, dapF and mrcB, restored susceptibility to cefoxitin (FOX) and reduced the MICs of cefotaxime and ceftazidime, respectively, from the resistant to the intermediate category according to clinical breakpoints. The same mutants harboring a CTX-M-1-encoding plasmid fell into the intermediate or susceptible category for all three drugs. Individual deletion of dapF and mrcB in a clinical isolate of CTX-M-15-producing E. coli sequence type 131 (ST131) resulted in partial reversal of ceftazidime and cefepime resistance but did not reduce MICs below susceptibility breakpoints. Growth curve analysis indicated no fitness cost in a ΔmrcB mutant, whereas a ΔdapF mutant had a 3-fold longer lag phase than the wild type, suggesting that drugs targeting DapF may display antimicrobial activity, in addition to synergizing with selected cephems. DapF appeared to be a potential FOX helper drug target candidate, since dapF inactivation resulted in synergistic potentiation of FOX in the genetic backgrounds tested. The study showed that individual inactivation of two nonessential genes involved in cell wall biogenesis potentiates cephem activity according to drug- and strain-specific patterns

Processing of polymetallic sea nodules: An overview

Polymetallic sea nodules are the potential sources of copper, nickel, cobalt and manganese. As the land based resources of these metals are depleting very fast, a considerable R&D effort have been made all over the world to extract the metals from the sea nodules during the past four decades. The paper summarises the processes developed by various R&D organisations and metallurgical consortia for the extraction of metal values from the sea nodules. Since the copper, nickel and cobalt in the sea nodules are in oxide Forms and they associate in the lattices of iron and manganese minerals, for extraction of these metals the lattices are broken either by hydrometallurgical reduction or by reductive pyre-treatment. Based on this criteria, processing methods have been broadly divided into two categories : (i) pyrometallurgical treatment followed by hydrometallurgical processing and (ii) purely hydrometallurgical processing. Processes developed under these two categories have been discussed highlighting their merits and demerits. Pilot plant studies carried out by various metallurgical consortia like Knnecott Copper Corporation, Deep Sea Ventures, Metallurgie Hoboken - Overpelt, International Nickel Company are also given. The R&D efforts made in India in the processing of sea nodules during last one decade and the future programme are also discussed

Reduction of Emission from Aluminium Industries and Cleaner Technology

Aluminium metal is produced by electrolytic reduction of alumina in cells lined with carbon blocks. During the process of smelting different gaseous emissions like PFC (per flurocarbon).HF PAH (poly aromatic hydrocarbon), CO2, SO„ particulate matters etc. occur in to the atmosphere. The concentration of emission from a cell depends upon the type of cell, bath chemistry, scrubbing system and gas cleaning equipment used. These emissions cause severe environmental damages such as global warming and disease like fluorosis, cancer, asthma, emphysema, bronchitis etc. Through the development of newer technologies like, intro-duction of prebake technology, use of non-consumable (inert) anode, use of computer controlled and point feeding of alumina to the cell to control the frequency and duration of anode effects, use of low carbon pitch to replace tar, use of pollution monitoring and control equipment etc., there is a significant reduction in the emission levels. This paper deals with the factors infl-uencing the generation of these emissions and its reduction through the development of various cleaner technologies. Use of pollution control equipment and other remedial mea-sures to minimise the environmental pollution are also discussed

Production of Silicomanganese Alloy from Low Manganese Containing Leached Sea Nodules Residue

Leached sea nodules residue was used for the present study for exploring its utilization. The residue generated in ammoniacal-SO2 pressure leaching was water washed to reduce the sulphur content. To improve the Mn/Fe ratio in the residue, it was blended with Fe-Mn slag or Mn ore in the calculated amount and smelting was carried out in 50 kVA submerged arc furnace. Various parameters such as holding time, amount of reductant, power input etc. were investigated. The maximum recovery of Mn from residue blended with Fe-Mn slag and Mn ore was 58% and 65% respectively in the form of silicomanganese

Different applications of waste generated in reduction roasting – ammonia leaching of manganese nodules.

CSIR-NML, Jamshedpur has been engaged in technology development to recover valuable metals (Cu, Ni & Co) from manganese nodules (MN). Extensive R&D work led to development of a process based on reduction roast – ammonia leaching – solvent extraction (SX) – electrowining (EW) route. This process generates large amount of waste/residue (70% of the MN weight) after selective leaching of Cu, Co and Ni, which may be considered hazardous, if untreated, due to its fineness and heavy metal contents. Characterisation studies have shown that this leaching residue waste contains oxides/oxyhydroxides of Fe, Mn, Al and Si with a high porosity and surface area, which are suitable for catalytic activity and adsorption of various aqueous pollutants. In addition, appreciable amount of manganese content of the manganese nodule leached waste may be recovered for the improvement of the economics of MN processing. Keeping these in view, studies for utilisation of waste leach residue have been carried out in three different ways: i) The use of leaching residue as catalyst has been successfully assessed for decolourisation of methylene blue (MB). The surface complex between wMNR and MB at a rate limiting step followed by electron transfer from MB to active metal centre of wMNR and release of products has been found to be operative during the decolourisation process. ii) The potential of water washed leaching residue as adsorbent has been evaluated for removal of anionic pollutants phosphate (PO43-), selenite (SeO32-) and cationic pollutants like Cu2+ and Cd2+, showing a maximum phosphate uptake of 9.88 mgP g-1 and selenite uptake of 15.17 mg Se g-1 for wMNR calcined at 400 C. The monolayer adsorption capacities (Qo) has been found to be temperature dependent showing 26.95 mg g-1 and 40.32 mg g-1 at 303 and 323 K, respectively for Cu2+ ion while the values are 32.23 and 38.14 mg g-1 at 303 and 323 K, respectively for Cd2+ adsorption. iii) In the third application of leached residue, a value added material like silicomanganese alloy has been produced by smelting of MN leaching waste in a 50 kVA electric arc furnace, with manganese recovery of about 77%

Lead sorption by sea nodule residue generated in reduction roasting – ammonia leaching.

Residue generated in reduction roast – ammonia leaching of sea nodules has been utilised for the remediation of aqueous lead. Characterization of sea nodule residue (SNR) reveals fine granulometry (d50 = 11.4 µm) and high surface area of 66.7 m2 g-1. Batch adsorption experiments have been performed varying different parameters. Equilibrium experimental data fitted well in the Langmuir isotherm and derived maximum adsorption capacity (qm) of lead onto SNR has been found to be 840.34 mg Pb(II)/g SNR at 303 K. The qm enhanced to very high value of 2500 mgPb/gSNR upon raising the temperature to 323 K. The pseudo second-order model has been found applicable to the lead removal kinetics