Efficient use of Magnetite in Coal Beneficiation Plants for Heavy Media Separation - A case study

Coal is a major commercial source of energy as a solid fuel for steel plants. The beneficiation of run of mine coal is mostly done by gravity separation using heavy media. Magnetite is the most widely used material for heavy media because of its higher stability in suspension, higher specific gravity, lower viscosity and easy avai-lability.Worldwide, almost 60% of total coal beneficiation is carried out by heavy media process. In India in 80% cases the heavy media used is magnetite. The paper esse-ntially deals with the magnetite stability factors, its preparation and recovery processes, its operational utilization and the existing systems in some Indian coal washing plants. A case study to operating system has been made with a view to identifying the major demerits and difficulties existing therein. Some remedial measures as applicable under Indian conditions have also beensuggested

Bioadhezivne vaginalete s klotrimazolom: priprava i evaluacija

In this study, a bioadhesive dosage form of clotrimazole was designed using a combination of bioadhesive polymers Carbopol 934P, sodium carboxymethylcellulose and sodium alginate in different ratios. The bioadhesive strength was evaluated by measuring the force required to detach the tablets from porcine vaginal mucosal membrane. The strong interaction between polymer and mucus lining of the tissue helps in increasing the contact time and permits localization of activity. Carbopol 934P showed maximum bioadhesion and required maximum force for detachment; the force required for detachment was directly proportional to its content. The formulations were tested for their swelling behavior using agar gel plate method. The swelling index was a function of the concentration of the hydrophilic polymer and the formulations containing Carbopol 934 P and sodium carboxy methylcellulose were found to swell to a greater extent than those containing carbopol and sodium alginate. In vitro release studies showed that the batch consisting 2: 1 ratio of Carbopol 934P: sodium alginate (batch C3) released clotrimazole over 24 h. The similarity factor showed that the dissolution profiles of fresh and aged tablets was similar, suggesting good stability of vaginal tablets prepared using a combination of Carbopol 934P and sodium alginate.U radu je opisana priprava bioadhezivnih vaginaleta s klotrimazolom, kombinacijom nekoliko bioadhezivnih polimera u različitim omjerima (Carbopol 934P, natrijeva sol karboksimetilceluloze i natrijev alginat). Bioadhesivnost je određena mjerenjem sile koja je potrebna za odvajanje tablete s vaginalne mukozne membrane svinje. Zbog jake interakcije između polimera i mukoze produljilo se vrijeme kontakta pripravka s kožom i lokaliziralo djelovanje lijeka. Maksimum bioadhezije postignut je uz Carbopol 934P, a sila potrebna za odvajanje pripravka bila je proporcionalna njegovom udjelu. Pripravcima je ispitana sposobnost bubrenja koristeći metodu s agarnim pločama. Indeks bubrenja ovisio je o koncentraciji hidrofilnog polimera. Pripravci s karbopolom i karboksimetilcelulozom jače su bubrili od pripravaka s karbopolom i natrijevim alginatom. In vitro ispitivanja pokazala su da se iz pripravaka s omjerom karbopola i natrijevog alginata u omjeru 2 : 1 (pripravak C3) oslobađao klotrimazol tijekom 24 h. Profil oslobađanja bio je sličan iz svježe pripravljenih i starih vaginaleta, što ukazuje na njihovu stabilnost

Uzbuda autoionizacijskog stanja u Na udarom elektrona

Electron-impact integral cross sections for the excitation of the lowest lying autoionizing level generated by the inner-shell 1s2 2s2 2p6 3s 2S e → 1s2 2s2 2p5 3s2 2P 0 complex transition in sodium (Na) atomic system have been calculated. In the calculation, single-configuration Hartree-Fock (HF) wave functions for both initial and final states involved in the transition matrix element within the asymptotic Green function approximation (AGFA) proposed by Tiwary (1981) were employed. The calculation was done exactly in the same way as in the earlier work in the case of the lightest alkali-metal atom lithium (Tiwary (1985), Tiwary, Macek and Madison (1985)) and the heaviest alkali-metal atom caesium (Tiwary (1983)) in the bombarding energy range from the threshold to 1500 eV. For the first time, Tiwary (1983) predicted the resonance behaviour in near vicinity of the excitation threshold in Cs using AGFA. Feuerstein et al. (1998) performed the experiment and observed resonance behaviour in the neighbourhood of excitation threshold in Na. Comparison has been made with available relevant experimental observations and other theoretical predictions. Our present AGFA theoretical result is qualitatively in accord with the experimental results.Izračunali smo integralne udarne presjeke za uzbudu najnižeg autoionizacijskog stanja koje nastaje udarom elektrona te putem kompleksnog prijelaza 1s2 2s2 2p6 3s 2S e Q 1s2 2s2 2p5 3s2 2P 0 među unutarnjim ljuskama u atomima natrija. U računu smo primijenili jedno-konfiguracijske Hartree-Fockove (HF) valne funkcije za odnosna početna i konačna stanja u matričnom elementu unutar asimptotskog približenja za Greenove funkcije (AGFA), predloženog Tiwary-em (1981). Račun je proveden točno na način kao u ranijem radu za najlakši alkalijski metalni atom litij (Tiwary (1985), Tiwary, Macek and Madison (1985)) i najteži alkalijski metalni atom cezij (Tiwary (1983)), za energije elektrona od praga do 1500 eV. Tiwary (1983) je prvi predvidio rezonanciju blizu iznad uzbudnog praga u Cs primjenom AGFA-e. Feuerstein et al. (1998) izveli su mjerenja i vidjeli rezonanciju u blizini uzbudnog praga u Na. Načinili smo usporedbu poznatih eksperimentalnih podataka i drugih teorijskih predviđanja. Naši su sadašnji teorijski rezultati u skladu s eksperimentalnima

Comparison of methods for evaluating the suitability of Vertisols for Gossypium hirsutum (Bt cotton) in two contrasting agro-ecological regions

This is the author accepted manuscript. The final version is available from Taylor and Francis (Routledge) via the DOI in this record.Cotton (Gossypium sp.) is a major crop grown under rainfed conditions in Vertisols and associated soils in semi-arid tropical (SAT) regions of Peninsular India. In recent years, cotton productivity has declined due to various biophysical factors including pest and diseases, seasonal water stress soil degradation and poor crop management practices. In this study, we compare two methods for evaluating the suitability of Vertisols for cotton in contrasting two agro-ecological regions viz., sub-humid moist (SHM) region and semi-arid dry(SAD) were characterized. Twelve cotton growing Vertisols (seven from SHM and five from SAD) were evaluated for their suitability for cotton cultivation using soil quality index (SQI) and modified Sys-FAO method. SQIs were calculated using the weighted additive index from transformed scores of selected indicators by principal component analysis. For Sys-FAO method both biophysical and soil characteristics were considered for suitability evaluation. We found that the soils of SHM region were moderately suitable for cotton cultivation with soil moisture as the major limiting factor, whereas the soils of SAD region are marginally suitable due to high exchangeable sodium percentage and poor hydraulic conductivity. From this, it may be concluded that the weighted SQI has better agreement with the cotton yield

High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions: Experimental Realization

Conversion of carbon dioxide into selective hydrocarbon using a stable catalyst remains a holy grail in the catalysis community. The high overpotential, stability, and selectivity in the use of a single-metal-based catalyst still remain a challenge. In current work, instead of using pure noble metals (Ag, Au, and Pt) as the catalyst, a nanocrystalline high-entropy alloy (HEA: AuAgPtPdCu) has been used for the conversion of CO2 into gaseous hydrocarbons. Utilizing an approach of multimetallic HEA, a faradic efficiency of about 100% toward gaseous products is obtained at a low applied potential (−0.3 V vs reversible hydrogen electrode). The reason behind the catalytic activity and selectivity of the high-entropy alloy (HEA) toward CO2 electroreduction was established through first-principles-based density functional theory (DFT) by comparing it with the pristine Cu(111) surface. This is attributed to the reversal in adsorption trends for two out of the total eight intermediates—*OCH3 and *O on Cu(111) and HEA surfaces

Influence of irrigation water on black soils in Amravati district, Maharashtra

In view of earlier reports on the occurrence of saltaffected shrink-swell soils in the Purna valley areas in Amravati district of Maharashtra, the present study was carried out to assess the current nature and extent of soil degradation due to use of irrigation water. Results indicate that the irrigation water used to raise agricultural crops in Amravati, Bhatkuli, Warud and Daryapur tehsils contains enough soluble Na-ions and residual sodium carbonate as the water belongs to C4S2 and C4S1 class of the United States Salinity Laboratory. The anthropogenic activities by introducing irrigation have caused severe drainage problem in the shrink-swell soils of the district, which are highly clayey and smectitic that have inherent low permeability. Only exception is the better drained soils of Warud tehsil, which are endowed with Ca-zeolite that help to ward off the ill effects of irrigation. The study thus suggests that continuing the present anthropogenic activities might render the soils unsuitable for agricultural production in the future. In contrast, the soils which are not irrigated do not suffer from any serious degradation in terms of high exchangeable Na (ESP) and low saturated hydraulic conductivity (sHC), suggesting that it would be prudent to encourage rainfed agriculture in the district under improved management practices

Processes determining the sequestration and maintenance of carbon in soils: a synthesis of research from tropical India

Soil organic carbon (SOC) is the major determinant of soil quality, and it greatly influences global carbon cycling and climate change. This paper is a synthesis of the literature on soil carbon research in India, including soil organic and inorganic carbon stocks, in the form of thematic maps for national and regional level planning at bioclimatic systems and agroecological subregion levels in the country. The potential role of soils in mitigating the global warming effects of atmospheric CO2 is discussed using results from Indian tropical soils. The database on Indian soils collected through natural resource inventory and soil carbon and crop modeling approaches show that sequestration of atmospheric CO2 occurs as pedogenic carbonates and plays role as a soil modifier in enhancing soil organic carbon in the drier parts of the country through management interventions. Clearly, soils can act as a potential medium for sequestering atmospheric CO2 to mitigate the global warming effec