Tris(trimethyl-stannyl,-germyl, -sijyl)borates

137-13

A Geological Appraisal of Slope Instability and Proposed Remedial Measures at Kaliasaur Slide on National Highway, Garwal Himalaya

For over six decades Kaliasaur landslide (Lat. 30° 14\u27 30 N, Long. 78° 55\u27 50 E) is a nightmare on the Hardwar-Badrinath road in the Garhwal Himalaya. Located on a sharp bend on the left bank of river Alaknanda, it has emerged as a multi-tier repetitive major landslide, retrogressive in nature. Both surficial and deep seated movements have been monitored. The sliding in the upper layers have been predominantly in the colluvium but where interfaces of quartzite and shale participates, the sliding surfaces have been better defined and discrete. In the present paper, the authors have highlighted the geological, geomorphological and morphometric parameters to diagnose the factors responsible for instability of slope and the magnitude of the problems involved. A scheme of remedial measures which .include modification of existing drainage pattern, timber piling for stitching of debris cover on to the slope, construction of retaining walls and putting back the vegetation on the slope are recommended for control of the landslide

Thin Layer Chromatography of Pesticides and Their Residues

Recent progress in the analysis of organo-phosphorus, organo-chlorine, carbamate, urea, uracil pesticides and their residues by thin layer chromatorgraphic methods employing chemical and enzymatic methods is reviewed

Recovery of Cu, Ni, Co and Mn from sea nodules by direct reduction smelting

Polymetallic nodule contains various metals like copper, nickel, cobalt, manganese, iron, lead, zinc, aluminum, etc. Of these, copper, nickel and cobalt are of much importance and in great demand world over. In fact, due to their extensive technological use these three metals are fast depleting from the earth surface. Hence a world-wide research is progressing on sea nodules as an alternative future source of these metals. India is entirely dependent on imports to meet its requirements of cobalt and nickel both of which are most strategic in nature. In this respect, India has made remarkable progress in recovering these metals from sea nodules. The recovery process so far developed in India is based on either purely hydrometallurgical or pyro-hydrometallurgical routes. The processes generate very dilute leach solution, the downstream processing of which is very difficult. Generation of concentrated leach solution from sea nodule would make the process simpler and economical which may not be possible by direct leaching process. Therefore, it has been planned to explore direct smelting of sea nodules to recover copper, nickel and cobalt along with part of iron in the form of alloy followed by individual metal recovery through matte formation and dissolution. Initial studies on direct reduction smelting of Indian sea nodule were conducted using coke as reductant in lab scale experiments. Various parameters like smelting temperature, reductant concentration, holding time etc. have been optimized to obtain an alloy of suitable composition. At a smelting temperature of 1400 oC, recovery of 90-92% Cu, 92-95% Ni and 80-85% Co is obtained in the form of alloy in a recrystallized alumina crucible which can be further treated to recover these metals in pure form. The iron content in the alloy varies significantly with coke concentration. The slag generated after smelting can be directly treated for production of standard grade Fe-Si-Mn without blending

Alkoxide Complexes of Some Tri- & Tetra-valent Metals: Part I- Conductometric & Potentiometric Studies on Some Aluminium Alkoxide Complexes in Non-aqueous Solvents

256-25

Synthesis of Apparently Covalent Double Alkoxides of Rubidium & Caesium

878-87

N,N-Diethylamino-oxy Derivatives of Dialkyltin(IV)

64-6

Microstructural Study of Galvanized coatings formed in Pure as well as Commercial Grade Zn Baths

The hot dip galvanizing is a complex metallurgical process wherein a steel strip is immersed in a zinc alloy bath normally between 450 and 480°C. The protective coating that is formed consists of a series of intermetallic Fe—Zn compound layers, which have been identified as gamma (r), delta (6), zeta (4) and an outer eta (T) layer, highly rich in Zn. There is no apparent delay in the formation of 4 or 6 phases (less than 5 s reaction time) in pure Zn bath as well as the commercial grade Zn bath. The gamma (I') phase is formed after an incubation time of 30 s at a bath temperature of 470°C in the pure Zn bath. The forma-tion and growth of F phase, however, is delayed in the commercial grade Zn bath. The last morphological feature is the formation of a second 4 layer at the 4/6 interface in reaction time above 30 s. Presence of Pb in the comme-rcial grade Zn bath seems to increase the overall coating thickness. Commercial grade Zn, however, enhances the dross formation in the bath and detoriates the quality of the coating. Presence of transverse cracks as well as entrapment of dross particles in these coatings is attr-ibuted to the less compact coatings that are formed in the commercial grade Zn baths. The present investigation is an effort to have a better understanding of the kinetics of growth and morphology of the coatings during the galva-nizing process in the pure as well as commercial grade Zn baths

Fast Algorithms For Josephson Junction Arrays : Bus--bars and Defects

We critically review the fast algorithms for the numerical study of two--dimensional Josephson junction arrays and develop the analogy of such systems with electrostatics. We extend these procedures to arrays with bus--bars and defects in the form of missing bonds. The role of boundaries and of the guage choice in determing the Green's function of the system is clarified. The extension of the Green's function approach to other situations is also discussed.Comment: Uuencoded 1 Revtex file (11 Pages), 3 Figures : Postscript Uuencode

Towards Sustainable Alumina Production

This paper, an overview • of research pursued at NML towards sustainable alumina production, ',deals with: (a) a chemical beneficiation of red mud to recover all its constituents, and (b) a novel process to reduce the alumina and soda content of red mud using mechanochemical activation (MA) of bauxite. As a part of the study on chemical-beneficiation of red mud, phase stability in the system Fe203-A1203-Na2CO3- C has been investigated using free energy minimization. Using these results, a process involving solid-state carbothermic reduction of red mud in the presence of soda, water leaching for alumina recovery and magnetic separation of leach residue for the sepa-ration of iron and TiO2 rich _fraction has been evaluated. Experimental results are explained using extensive X-ray diffraction and SEM-EDS studies on various solid residues generated in the different stages of the process. Mecha-nical activation of bauxite is investigated: (a) as pre-treatment to the Bayer process; and (b) mechanochemical leaching of bauxite, i.e. simultaneous milling and leaching of bauxite. The superiority of mechanochemical leaching over the existing Bayer 1. process practice and MA as pretreatment has been established. Using the novel process the approach of mechanochemical leaching, reduc-tion in soda content of red mud to less than 1% and alumina content to less than half is possible with additional benefits in terms of moderation in process condition, simplicity of the process and efficient utilization of energy. Merits of the investigated processes have been highlighted vis-à-vis previous studies on red mud utilization and minimization of its enviro-nmental impact