Metal-insulator transition in an aperiodic ladder network: an exact result

We show, in a completely analytical way, that a tight binding ladder network composed of atomic sites with on-site potentials distributed according to the quasiperiodic Aubry model can exhibit a metal-insulator transition at multiple values of the Fermi energy. For specific values of the first and second neighbor electron hopping, the result is obtained exactly. With a more general model, we calculate the two-terminal conductance numerically. The numerical results corroborate the analytical findings and yield a richer variety of spectrum showing multiple mobility edges.Comment: 4 pages, 3 figure

Use of blue dust in sintering

Sintering studies were undertaken through a full factorial design of experi¬ment to estimate the quantitative effect of blue dust along with other process variables. Responses from the experiments were then correlated with the process variables through a regression equation. The coefficients of the equation indicated that the coke breeze exerted maximum influence on the strength. It was possible to incorporate blue dust to the extent of 40% with respect to total iron ore fraction without impairing the properties of sinter

Magneto-transport in a mesoscopic ring with Rashba and Dresselhaus spin-orbit interactions

Electronic transport in a one-dimensional mesoscopic ring threaded by a magnetic flux is studied in presence of Rashba and Dresselhaus spin-orbit interactions. A completely analytical technique within a tight-binding formalism unveils the spin-split bands in presence of the spin-orbit interactions and leads to a method of determining the strength of the Dresselhaus interaction. In addition to this, the persistent currents for ordered and disordered rings have been investigated numerically. It is observed that, the presence of the spin-orbit interaction, in general, leads to an enhanced amplitude of the persistent current. Numerical results corroborate the respective analytical findings.Comment: 7 pages, 7 figure

An Approach to Beneficiation of Apatite Ore of Purulia

West Bengal Mineral Development and Trading Corporation operates the apatite mine in Purulia District of West Bengal. The produce three grades of samples, i.e. (i) High grade above 30% P2O5 (ii) Average grade of about 20% P2O5 and (iii)Low grade of 12% P2O5. The average is directly marketed as fertiliser for application in tea garden etc. The medium or average grade sample is mined from areas around the main ore body and contains substantial amount of ferruginous material besides other gangue minerals. The low grade ore is dumped separately and occasionally blended with high grade of ore to prepare the average grade for direct marketing. Thus every bit of apatite from the mines is used except for the top soil. But with reduc-ed demand, the manufacturer is faced with a selling problem and reduced production. Value addition by way of making high grade product is one option to pursue with. The typical problem is of iron removal as presence of high iron hinders value addition in terms of phosphate during down stream operation. Studies on the average grade sample indicated that using suitable processing steps the phos-phate content could be increased to +38% P205 with very low content of iron & silica. The present paper deals approach adopted in beneficiating the average grade apatite ore of Purulia. Key Words: apatite, Purulia, iron, magnetic separation, flotation

Beneficiation studies on reject dump magnesite sample from Talur Magnesite Mines, Karnataka

Flotation studies on reject dump magnesite sample were conducted using oleic acid emulsion as collector and sodium silicate as depressant. The representative sample assayed SiO, 6.1 %, MgO 41.85%, CaO 2.25% and Fe2O3 1.2%. Mineralogical studies showed that gangue minerals were mostly quartz liberated at grind below 208µ except for serpentine which needs a still finer grind of 107µ Flotation studies in batch scale (I kg batch) indicated that a concentrate analysing 2.02% silica with a yield of 58.5% could he obtained by roughing followed by one cleaning while by adding two more cleaning stages, a concentrate with a silica content of 0.9% with a yield of 32.0% could be produce

Optimisation of Process Variables in Sintering through Statistical design of Experiments

An attempt has been made to quantify the effects of the variables on strength in sintering of iron ore/blue dust received from Bailadila, NMDC. For this, the method of design 2n factorial experiment is used to obtain a response surface equation. Results indicate if the coke breeze increases in the range of variation of the variable in sintering, the strength increases but strength decreases when moisture increases from lower level to higher level. Blue dust does no effect the strength. The optimum levi (-4: variables for the maximon strength of the sinter produ(A is determined by the method of hexagonal design of experjnent. The results indicate that for a basicity of 1.9 an acceptable quality of sinter can be produced. Blue dust amounting to 40.0% of all the iron ore fines taken together can be incorporated in the raw mixture without imparting the strength of the finished sinter