An Investigation on the Sulfuric Acid Leaching of Low Grade Rock Phosphate

[From the Introduction] The practice or using phosphatic materials as fertilizers goes back so far there is no record of when and where they were first employed. The dung of birds was used over 200 years B.C. The use of bones is also an ancient practice. These materials continued to be the main sources of phosphorus and phosphoric acid until after the middle of the nineteenth century, when the Napoleonic battlefields, which had been a source of bone, could no longer be worked profitably. The treatment of phosphatic materials with sulfuric acid was first suggested by Liebig in 1840. In 1842 Lawes took out the first English patent for acidulation of bones and later the same process was applied to rock phosphate. Mineral phosphates known as coprolites were discovered in England in 1845 and in France seven years later. Rock phosphate was first developed in South Carolina in 1867. Since that time the United States has been the foremost phosphate producing nation in the world. The chief deposits of rock phosphate in this country are located in Florida, Tennessee, Montana, Utah, Wyoming, and Idaho. Other important deposits have been found in Belgium, Germany, Spain, Russia, Algeria, Tunis, Egypt, and Morocco. The most extensively exploited deposits of phosphate in the world are those of Florida. The phosphate deposits of this country which rank next to Florida in commercial importance are those of Tennessee. Tennessee is well situated for the distribution of fertilizer material to the southern and middle western states. Its phosphate deposits occur in the central basin of Tennessee and in the western part of the Highland Rim. The area covers approximately 7000 square miles. Most of the phosphate rock marketed in 1936 came from the brown-rock fields of Maury, Sumner, Giles, Davidson, and Hickman counties. Considerable blue rock was shipped from Lewis and Hickman counties, and a little white rock from Perry County. There are three economically important types of rock phosphate in Tennessee, namely, the brown, blue, and white phosphate. The deposits of brown rock phosphate are generally conceded to be formed from phosphatic limestone by the washing out of the more soluble carbonate of lime. The blue rock is a conglomerate deposit derived in part from the underlying Ordovician limestone and partly from remains of later marine life. The white phosphate has been divided into three classes by Hayles, namely, the stony, breccia, and lamellar varieties. The latter is the richest and most plentiful. The breccia variety consists of chert fragments imbedded in a matrix of high grade phosphate. The stony phosphate consists of silicious skeletons formerly filled with carbonate of lime but now containing phosphate. The two commercially important acids used in acidulation of rock phosphate today are sulfuric and phosphoric acids. Phosphoric acid is derived from the rock itself. The two distinct methods of producing phosphoric acid are, first, the sulfuric acid process and, second, the volatilization process. ln the sulfuric acid process phosphoric acid is produced from the tricalcium phosphate of the rock as shown in the following reaction: Ca₃(PO₄)₂+3H₂SO₄ = 3CaSO₄+2H₃PO₄. The term, leaching, as used throughout this paper will refer to the process in which the above reaction takes place. In the volatilization process silica and coke are added to the rock and the mixture heated to about 1500°C either by burning part of the coke in a blast furnace or by heating with an electric arc. The general course of this reaction is usually represented as follows: Ca₃(PO₄)₂+3SiO₂+5C = 3CaSiO₃+P₂+5CO. To produce phosphoric acid from the phosphorus volatilized in the above reaction the phosphorus is oxidized to phosphorus pentoxide and this oxide hydrolyzed to phosphoric acid. Much of the phosphate rock in Tennessee is of such low grade that if it were simply acidulted with sulfuric acid the resulting superphosphate would be too low in plant food value to warrant extensive distribution. The volatilization method has not yet been developed so that it can use the low grade rock satisfactorily. The sulfuric acid process is probably best adapted for the utilization of low grade rock phosphate. For this reason, an investigation on the leaching properties of three low grade rock phosphates was made. The low grade rock phosphates chosen were from Hickman, Johnson, and Ferry Counties of Tennessee

Negative-Triangularity Configuration on EAST: Analysis of engineering limitations on superconducting, D-shaped, target-diverted plasmas

Thermonuclear fusion is so named because of the high temperature that the majority of the fuel must maintain such that nuclei can overcome the electrostatic force, fuse, and produce energy. However, the ions and electrons (plasma) are so hot that any material used to confine them would be destroyed. To achieve confinement while maintaining the 50,000,000 K temperature needed for self-sustaining fusion, magnetic confinement is needed. As of 2019, the tokamak is the leading candidate for a practical fusion reactor. In recent years, tokamak research has repeatedly shown that the edge magneto-hydrodynamic stability is critical for handling the power to the walls and the divertor plates which is now and will most likely continue to be a limiting factor in the International Thermonuclear Experimental Reactor (ITER) and the DEMOnstration Power Station (DEMO). Recent experiments at Tokamak à Configuration Variable (TCV) and DIII-D have shown that a Negative-Triangularity Configuration (NTC) has a larger power handling area on the Low-Field-Side (LFS) divertor target plate and improved edge stability. However, there have been relatively few NTC experiments performed so far and none of them have been performed on a superconducting tokamak with shaping capabilities similar to ITER. To expand upon the previous experiments on TCV and DIII-D this thesis addresses an initial test of the NTC capability of the Experimental Advanced Superconducting Tokamak (EAST) which has achieved a ¡ 6 s ohmic discharge Upper Singular Null (USN) target-diverted plasma with a lower triangularity of X! ≤ -0.09

Thermal quark production in pure glue and quark gluon plasmas

We calculate production rates for massless $(u,d)$ and massive $(s,c,b)$ quarks in pure glue and quark gluon plasmas to leading order in the strong coupling constant $g$. The leading contribution comes from gluon decay into $q\bar q$ pairs, using a thermal gluon propagator with finite thermal mass and damping rate. The rate behaves as $\alpha_S^2(\ln 1/\alpha_S)^2 T^4$ when $m, \alpha_S \rightarrow 0$ and depends linearly on the transverse gluon damping rate for all values of the quark mass $m$. The light quark ($u$, $d$, $s$) chemical equilibration time is approximately 10-100 $T^{-1}$ for $g=$2-3, so that quarks are likely to remain far from chemical equilibrium in ultrarelativistic nuclear collisions.Comment: 7 pages, 5 figures (available upon request), CERN preprint CERN-TH-6882/9

Vigilant Warrior™: A Selection Tool for Vigilance Performance

In this paper, we describe an individual differences model of vigilance performance—the ability to maintain one’s focus of attention and remain alert for prolonged periods of time—and summarize our model evaluation research. Our goal was an automated test battery (Vigilant Warrior™) that could be employed to select personnel with superior abilities for assignment to critical vigilance duties. Thus, we conducted extensive laboratory research to identify an optimal set of vigilance predictors and validate them against a simulated, real-world, electronic-display, battlefieldmonitoring task with high vigilance requirements. The results confirmed that an objective, Short Vigilance Task (SVT), coupled with analytic skill and stress-coping measures, could account for 33% or more of the criterion variance. Moreover, the SVT was the most powerful predictor in the battery. Analytic skill and situational variables contributed to vigilance performance, but to a lesser degree. Vigilant Warrior™ is currently receiving extensive field testing in military settings

The Economics of Rotational Grazing in the Gulf Coast Region: Costs, Returns, and Labor Considerations, Phase II

Profitability and labor associated with rotational grazing at three stocking rates and continuous grazing at a medium stocking rate are compared. On a per-acre basis, profits are lowest for low stocking rate rotational grazing. Labor is greatest on both per-acre and per-cow bases with high stocking rate rotational grazing.Time and Motion Study, Conservation, Louisiana, Cow-Calf, Farm Management, Production Economics, Q16,

A surgical team simulation to improve teamwork and communication across two continents: ViSIOT™ proof-of-concept study

Background: Team communication in operating rooms is problematic worldwide, and can negatively impact patient safety. Although initiatives such as the World Health Organization’s Surgical Safety Checklist have been introduced to improve communication, patient safety continues to be compromised globally, warranting the development of new interventions. Video-based social science methods have contributed to the study of communication in UK ORs through actual observations of surgical teams in practice. Drawing on this, the authors have developed a surgical team simulation-training model (ViSIOT™). A proof-of-concept study was conducted in the UK and USA to assess if the ViSIOT™ simulation-training has applicability and acceptability beyond the UK. Methods: ViSIOT™ training was conducted at two simulation centers in the UK and USA over a 10-month period. All surgical team participants completed a questionnaire (that assessed design, education, satisfaction and self-confidence in relation to the training). Descriptive and inferential statistics were performed for the quantitative data and thematic analysis was conducted for the qualitative data. Results: There was strong agreement from all participants in terms of their perception of the course across all sub-sections measured. Nine themes from the qualitative data were identified. The two countries shared most themes, however, some emerged that were unique to each country. Conclusions: Practical developments in the course design, technology and recruitment were identified. Evidence of the course applicability in the USA provides further affirmation of the universal need for team communication training within ORs. Further studies are required to assess its effectiveness in improving communication in OR practice

Thermal quark production in ultra-relativistic nuclear collisions

We calculate thermal production of u, d, s, c and b quarks in ultra-relativistic heavy ion collisions. The following processes are taken into account: thermal gluon decay (g to ibar i), gluon fusion (g g to ibar i), and quark-antiquark annihilation (jbar j to ibar i), where i and j represent quark species. We use the thermal quark masses, $m_i^2(T)\simeq m_i^2 + (2g^2/9)T^2$, in all the rates. At small mass ($m_i(T)<2T$), the production is largely dominated by the thermal gluon decay channel. We obtain numerical and analytic solutions of one-dimensional hydrodynamic expansion of an initially pure glue plasma. Our results show that even in a quite optimistic scenario, all quarks are far from chemical equilibrium throughout the expansion. Thermal production of light quarks (u, d and s) is nearly independent of species. Heavy quark (c and b) production is quite independent of the transition temperature and could serve as a very good probe of the initial temperature. Thermal quark production measurements could also be used to determine the gluon damping rate, or equivalently the magnetic mass.Comment: 14 pages (latex) plus 6 figures (uuencoded postscript files); CERN-TH.7038/9

A molecular survey across Madagascar does not yield positive records of the amphibian chytrid fungus Batrachochytrium dendrobatidis.

Madagascar harbors a rich and diverse amphibian fauna, with over 280 nominal species of native frogs, all of which are endemic to the island. Although many species are threatened predominantly by habitat destruction, so far this fauna has not experienced any enigmatic declines as amphibians have in other parts of the globe. The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), associated with mass amphibian die offs in Europe, the Americas and Australia has so far not been detected in Madagascar, but surveys so far were based mainly on histological examination of frog samples, with molecular data from only a single site. Here, we present results from a molecular screening of altogether 300 frog specimens belonging to 53 species in 13 genera, from 12 sites throughout Madagascar spanning all of Madagascar`s major bioclimatic regions and an array of different elevations from 20 to 2400 m above sea level. All samples were analyzed using a standard quantitative real time polymerase chain reaction (qPCR) assay and yielded only negative results, suggesting the widespread absence or very localized and low prevalence of the amphibian chytrid fungus across Madagascar during the sampling years 2006 and 2007.This research was supported by Conservation International, by the Spanish Ministry of Science, by the Volkswagen Foundation, and by The US National Science Foundation (EF-0723563 and 1120283)Peer Reviewe

Thermal Fermionic Dispersion Relations in a Magnetic Field

The thermal self-energy of an electron in a static uniform magnetic field $B$ is calculated to first order in the fine structure constant $\alpha$ and to all orders in $eB$. We use two methods, one based on the Furry picture and another based on Schwinger's proper-time method. As external states we consider relativistic Landau levels with special emphasis on the lowest Landau level. In the high-temperature limit we derive self-consistent dispersion relations for particle and hole excitations, showing the chiral asymmetry caused by the external field. For weak fields, earlier results on the ground- state energy and the anomalous magnetic moment are discussed and compared with the present analysis. In the strong-field limit the appearance of a field-independent imaginary part of the self-energy, related to Landau damping in the $e^{+}e^{-}$ plasma, is pointed out.Comment: Latex+FEYNMAN.tex. 5 figures and special files are submitted using Figure