Froth Flotation and its Application to Concentration of Low Grade Iron Ores

Froth flotation is a process used to separate minerals, suspended in liquids, by attaching them to gas bubbles to provide selective levitation of the solid particles. It is most extensively used process for the separation of chemi-cally similar minerals, and to concentrate ores for econo-mical smelting. Flotation is a selective process and can be used to achieve separation from complex ores such as lead-zinc, copper- zinc etc.Initially developed to treat the sulphides of copper, lead, and zinc, the field of flotation has now expanded to include oxides, such as hematite and cassiterite, oxidised minerals, such as mala-chite and cerussite, and non-metallic ores, such as fluo-rite, phosphates, and fine coal

Self-starting passive phase conjugate mirror with Ce-doped strontium barium niobate

We report the use of Ce-doped SrxBa1−xNb2O6, x=0.60 and 0.75, as the holographic four-wave mixing medium in the construction of a self-starting passive phase conjugate mirror using internal reflection. Without correcting for Fresnel reflections, a steady-state phase conjugate reflectivity of 25% was measured with Sr0.75Ba0.25Nb2O6:Ce. The distortion correcting property of such a mirror was demonstrated using an imaging experiment

Photorefractive properties of Ce- and Ca-doped Sr0.6Ba0.4Nb2O6

We present the results of experimental study of the absorption coefficient, two-beam photorefractive coupling constant, and photorefractive response time of a doubly Ce- and Ca-doped Sr0.6Ba0.4Nb2O6. This crystal displays enhanced photorefractive response at near infrared wavelengths when compared to Ce-doped SBN:60. The temperature dependence of the coupling constant over the range from –30 to 40 °C has also been studied

Photorefractive Properties of Undoped and Doped Single Crystal SBN:60

We present the results of our theoretical and experimental studies of the photorefrac-tive effect in single crystal SBN:60, SBN:Ce, and SBN:Fe. Specifically, the two-beam coupling coefficients, response times and absorption coefficients of these materials are given

Photorefractive Properties Of Undoped, Cerium-Doped, And Iron-Doped Single-Crystal Sr_(0.6)Ba_(0.4)Nb_2O_6

We present the results of our theoretical and experimental studies of the photorefractive effect in single-crystal SBN:60, SBN:Ce, and SBN:Fe. The two-beam coupling coefficients, response times, and absorption coefficients of these materials are given

Photorefractive Properties Of Ferroelectric BaTiO_3 and SBN:60

The results of theoretical and experimental studies of the photorefractive effect in two different classes of materials--perovskite BaTiO_3 and tungsten bronze SBN--have been examined. The interesting features of these measurements indicate that two-beam coupling coefficients, response times, and absorption coefficients enhanced significantly in doped crystals which appear to be suitable for future device concepts. A comparison of these materials showed that Ce-doped SBN:60 single crystals are superior to BaTiO_3 for use in photorefractive applications due to higher two-beam coupling, sensitivity, and overall flexibility of tungsten bronze crystals

Molecular Interaction Studies in Ternary Liquid Mixtures of Quinoline at Varying Temperatures

Density r, Viscosity η, and ultrasonic velocity u, have been measured in pure Quinoline, o-cresol, m-cresol, p-cresol and methanol and in their ternary liquid mixtures with quinoline and methanol as common components at 303.15, 308.15, 313.15 and 318.15K over the entire range of composition. From these experimental data, various thermo-acoustic parameters such as excess molar volume VmE, excess ultrasonic velocity uE, viscosity deviation Δη and excess Gibb’s free energy of activation for viscous flow ΔG*E have been calculated. The deviation/excess parameters were plotted against the mole fraction of quinoline over the whole composition range. The observed negative and positive values of deviaiton/excess thermo-acoustic parameters were explained on the basis of intermolecular interactions present in these mixtures

Beneficiation of Non-Coking Coal for Generating Low Ash Clean Coal

The rapid upsurge in India’s electricity demand with passage of time is consensual perception among energy planners and coal certainly will occupy the centre stage in driving the growth momentum of the country’s economy at macro-economic level. 80% Consumption of non-coking coal is attributable to power sector and India’s definitive coal reserves is estimated to be around 93 billion tonnes (source: Ministry of Coal), and with focussed scientific exploitation of the same, it is adept in catering to energy generation requirement of the country, spanning over next 5-6 decades. However, Indian coal has been observed to be of low quality on account of its high ash content attribute and non-coking category coal constitutes sizeable quantity of near-gravity materials (NGM), which entails beneficiation to suit end-user. The beneficiated coal has immense potential for being used as a blendable mix for metallurgical applications and such blend formulation of clean coal facilitates maximising the infusion of non-coking coal with scarce coking coal for catering to metallurgical industries, enabling lesser dependence on import of high-rank low ash content coke. The present manuscript is aimed at generating low ash (10%) clean coal from high ash (28.88%) non coking coal. The coal was characterised thoroughly in terms of petrography characteristics, size analysis, washability and chemical composition and the gross calorific value of the coal was observed to be 5327 Kcal/kg. The processing was initiated at a top size of 12.5 mm and efforts were made to achieve the objective of 10% ash level in the clean coal at the coarsest possible size adopting advanced gravity based techniques. Tactical combination of gravity separation and flotation techniques yielded clean coal (10% ash content) with maximum possible produce and results were discussed in light of experimental details

Volumetric properties of binary mixtures of cyclohexane with 2-ethoxyethanol at 303.15, 308.15, 313.15 and 318.15 K

1206-1210The excess molar volumes (VmE) for binary liquid mixtures of cyclohexane+2-ethoxyethanol have been calculated from the experimental values of density and ultrasonic velocity at temperatures 303.15, 308.15, 313.15 and 318.15 K and atmospheric pressure over the entire composition range. The results have been used to estimate the partial molar volumes m,i of the components. The excess values have been fitted to Redlich-Kister polynomial equation. The changes of VmE and with composition and temperature have been discussed with reference to the nature of interactions between the component molecules

Surface Chemical and Settling Studies on Hematite, Quartz and Kaolinite in Presence of Organic Reagents

The industrial practice of beneficiation of iron ores produces substantial amount of slimes which causes loss of iron values and environmental pollution. Slimes consists of extremely fine grained iron bearing minerals, impurities and poses problem in processing by conventional beneficiation techniques. The present study aims to develop flocculation technique for selective separation of iron bearing mineral from slimes. Initial experiments were directed towards understanding surface chemical properties of constituent minerals viz. hematite, quartz and kaolinite with or without organic reagents such as tannic acid, starch and polyacrylamide-co-acrylic acid (m.w.-150 lakh). In this paper, the results of flocculation-dispersion experiments on individual samples of hematite, quartz and kaolinite are discussed as a function of different process parameters such as pH, flocculation time and dosages of reagents. Based on the studies, conditions were established for selective separation of hematite from quartz and kaolinite. The results of flocculation-dispersion of individual minerals were applied to ternary synthetic mineral system