Recent trends in photoelectrochemical cells

A brief survey is presented of the recent developments and emerging trends in research in photoelectrochemical cell for solar energy conversion utilizing semiconductor electrodes

Preparation and characterization of non-random YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB>-Ag composite

Silver addition to the high Tc superconductor, YBa2Cu3O7 (YBCO) is known to improve its mechanical properties and critical current (Jc) characteristics. We have synthesized the superconductor-metal composite YBCO-Ag by an electroless process at room temperature (using sucrose or hydrazine hydrate in an alkaline medium). The latter method produces a non-random coating whereby each grain of YBCO is coated uniformly by silver. The intrinsic high Tc of 90 K of YBCO can be recovered by compaction of the composite and subsequent heat treatment (900&#176;C and 600&#176;C) in oxygen

Characterization of Srikurmum and Navaladi Beach Placer Minerals

Two different beach placer samples from Srikurmum of Andhra Pradesh and Navaladi of Tamilnadu were collected and characterized in terms of their total heavy mineral content by heavy media as well as magnetic separation studies. Navaladi beach placer sample contains higher amounts of total heavy minerals than that of the Srikur-mum beadh. Mineralogical analysis on both the samples revealed high amounts of garnet and minor quantities of ilmenite. The particle size of garnet is coarser than that of ilmenite. EPMA results indicated that garnet is of almandine variety. The Eastern Ghats metarnotphic belt, covering both the areas, is considered to be the source of these beach placer minerals

Value Addition of Indian Iron Ore Fines by Column Flotation - Few Case Studies

The Government of India highlighted Processing and utili-zation of iron ore fines as a prerequisite to meet the domestic raw material requirements for the projected 110 million tonnes of domestic steel production by the year 2019-20 in the National Steel Policy announced in Nov-ember 2005. This would require 190 million tonnes of iron ore. The depletion of high grade iron ore and increased generation of fines during mining and handling and demand for high grade iron ore fines for export has necessitated the processing of low to medium grade fines. The R&D efforts undertaken at NML-Madras Centre, India in this direction have been highlighted. Flotation in general and Column Flotation in particular appear to be promising in addressing this problem. This would also mitigate the environmental problem created by the dumping of huge quan-tities of low and medium grade iron ore fines. Three case studies involving iron ore fines of varying silica and alumina content from Goa and Bellary-Hospet regions of India were discussed. The results clearly indicate the feasibility and significance of flotation process in treat-ing the fines to obtain marketable concentrates

Photoelectrochemical properties of metal-cluster oxide compounds, A<SUB>2</SUB>Mo<SUB>3</SUB>O<SUB>8</SUB> and (LiY)Mo<SUB>3</SUB>O<SUB>8</SUB>

PEC studies on the single crystals of the metal-cluster oxide compounds. A2Mo3O8 (A = Zn, Mg, Fe), and polycrystalline LiYMo3O8 are reported. The photoresponse behaviour is attributed to the Mo d-d transition. The photopotential, the photocurrent vs applied voltage and the wavelength data indicate that n-Zn2Mo3O8 is stable and possesses a small and indirect band gap of 1.55 eV and a direct band gap of 1.9 eV. With change in A ions in A2Mo3O8, there is no significant change in the PEC properties. LiYMo3O8 is found to be of p-type. PEC studies show that excepting for poor electronic conductivity, A2Mo3O8 possesses all the requisitie characteristics of an ideal photoanode for PAE of water for trapping solar energy

Alteration characteristics of manavalakurichi beach placer illmenite, Tamilnadu.

The mineralogy and alteration characteristics of beach placer ilmenite from the Manavalakurichi coast were investigated by optical microscopy and electron probe microanalysis. Mineral chemistry by electron probe micro-analysis indicated ;enrichment of TI02, MgO, AI203, Cr203, Si02. K20, V205,. CaO and Na20 in the altered products ofilmenitc:. while there was a loss of iron oxide, maganesc oxide and zinc oxide from the ilmenite grains during weathering leading to leucoxen

Beneficiation of a Low Grade Limestone by Flotation Column

Beneficiation of a Low-grade limestone sample from Salem, Tamilnadu was carried out by pilot scale flotation column. Mineralogical studies have revealled that quartz, freldspar, pyroxene and biotitic as gangue minerals while pyrite, in trace quantitiew, appear as opaque along with dominating calcite. Reverse flotation was tried using two different commercial amines viz. Chem750F and Flotamine-D. The studies clearly suggest that it is possible to produce a limestone concentrat assying around 96-97% of CaCO3 with less than 1% SiO2

Processing of iron ore fines by column flotation – Part I & part II

The Government of India highlighted Processing and utilization of iron ore fines as a pre-requisite to meet the domestic raw material requirements for the projected 110 million tonnes of domestic steel production by the year 2019-20 in the National Steel Policy announced in November 2005. This would require 190 million tonnes of iron are. The depletion of high grade iron are and increased generation of fines during mining and handling and demand for high grade iron are fines for export has necessitated the processing of low to medium grade fines. The R&D efforts undertaken at NML-Madras Centre, India in this direction have been highlighted. Flotation in general and Column Flotation in particular appear to be promising in addressing this problem. This would also mitigate the environmental problem created by the dumping of huge quantities of low and medium grade iron are fines. Three case studies involving iron ore fines of varying silica and alumina content from Goa and Bellary-Hospet regions of India were discussed. The results clearly indicate the feasibility and significance of flotation process in treating the fines to obtain marketable concentrates

Reverse flotation studies on an Indian low-grade iron ore slimes

The present investigation deals with the recovery of iron values from the screw classifier overflow slimes from an iron ore washing plant by means of reverse cationic flotation as an alternate to direct anionic flotation. Selectivity index, an indicator of separation efficiency, was chosen as the response parameter for optimizing the quantity and evaluating a series of generically same but chemically different cationic collectors used in reverse flotation and for further optimization of other flotation process parameters. In the optimization, the main variables investigated were percent solids, collector and depressant dosage. An increase in the iron content of the concentrates is obtained with concomitant reduction in Si02 and Al203levels