PUBIFICATION OF WET PROCESS PHOSPHOHIC ACID BY SOLVENT EXTRACTION WITH DIBUTYL ETHER. PART. I. LIQUID-LIQUID EQUILIBRIUM OF THE SYSTEM WATER-PHOSPHORIC ACID-DIBUTYL ETHER AT 25°C.

Solubility and liquid-liquid phase equilibrium data have been determinated for the ternary system water-Phosphoric Acid-Dibutyl Ether at 25°

Data for the binodal curve have been obtained by analyzing the phosphoric acid percentage in both aqueous and organic phases. The plait point composition has been calculated by the Hand, Coolidge and Sherwood methods. The phosphoric acid extraction capacity of dibutyl ether has been compared to that of several solvents previously studied in the Alicante Chemical Engineering Division, showing that dibutyl ether has a phosphoric acid extraction capacity similar to propyl-ether and lower than isoamyl alcohol.     

PURIFICATION OF WET PROCESS PHOSPHORIC ACID BY SOLVENT EXTRACTION WITH ISOAMYL ALCOHOL. PART II. STUDY OF THE IMPURITIES DISTRIBUTION.

ABSTRACT

In the present paper, information about the purifying of wet process phosphoric acid (WPA) by Isoamyl Alcohol (iA) is reported. Distribution coefficients of impurities such’ as Fe, Al, Mg, SO⁼ ₄and F, as well as the distribution of Phosphoric Acid (PA) and Isoamyl alcohol were obtained.

Furthermore the variation of the relative distribution coefficients and selectivities of the different impurities was studied as a function of the PA weight percent (wt%) in the organic phase. Removal of the impurities Fe, Al, Mg and SO⁼ ₄is favoured when decreasing PA wt% in the organic phase. Selectivity of F shows different behaviour, passing through a maximum when plotted against PA wt% in the organic phase     

LIQUID-LIQUID EQUILIBRIUM OF THE SYSTEM WATER-PHOSPHORIC ACID-DI-N-PROPYL ETHER AT 25 AND 40°C. INFLUENCE OF THE ISOMER PROPYL-ISOPROPYL ETHER ON THE APPEARANCE OF THREE LIQUID PHASES AT EQUILIBRIUM.

Solubility and liquid-liquid phase equilibrium data have been determined for the ternary systems Water-Phosphoric Acid-Di-n-propyl Ether as supplied by Merck (with about 6.4% of the isomer propyl-isopropyl ether), and Water-Phosphoric Acid-Di-n-propyl Ether (rectified up to less than 1% of propyl-isopropyl ether), at 25 and 40^°C The temperatures at which three liquid phases at equilibrium appeared were 28.0-28.2^°C and 49.0-50.0^°C, respectively. The presence of the isomer propyl-isopropyl ether causes these systems to split into three liquid phases at equilibrium     

Synthesis of the Bi2Sr2CaCu2O8+δ superconductor following a polymer matrix route

This paper presents a convenient polymer matrix synthesis route based on the use of metal acetates, which yields Bi2Sr2CaCu2O8+δ (2212 phase) with a Tc higher than 93 K, in air and within a short sintering time (6–12 h) at 855°C. The phase quality of the intermediate and final products has been analysed by powder X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy. Macroscopic superconducting characteristics have been determined by alternating-current magnetic susceptibility and direct-current magnetization. The results obtained on a large number of samples suggest that this preparation route is highly reproducible and leads to black-grained powders with excellent homogeneity within a relatively short processing time. The usefulness of these powders to obtain textured superconducting products has been explored and representative results are presented here. This revised version was published online in November 2006 with corrections to the Cover Date.     

Stress intensity factors for nozzle corner cracks

Stress intensity factors have been determined by means of the frozen stress photoelastic technique for nozzle corner cracks in pressure vessel models. The model geometry was chosen to represent a nuclear reactor vessel with a radial branch, and cracks of varying depth were introduced longitudinally. The results were compared to experimental data obtained from burst tests, thus extending their scope.     

PURIFICATION OF WET PROCESS PHOSPHORIC ACID BY SOLVENT EXTRACTION WITH DIBUTYL ETHER. PART II. STUDY OF THE IMPURITIES DISTRIBUTION

The results obtained when studying the purification of wet process phosphoric acid wdith dibutyl ether are reported. Percent PA, and impurities: Fe, Al, Mg SO₄ ^? and F^? extracted into the organic phase are shown. The variation of the percent extracted in to the organic phase for the different components has been studied as a function of the PA wt% in the organic phase. Results have been compared with those corresponding to other solvents previously studied. Dibutyl ether shows good purification behaviour for metallic impurities and SO₄ ^?, but seems to be not very suitable for F^? purification due to its high F^? extraction capacity.     

Some fatigue damage measures for longitudinal elements based on the Wohler field

In this paper, the problem of selecting damage measures and ways of accumulating damage due to a fatigue load history is dealt with. First, a statistical model and a normalization procedure, that allow using a reference stress level or a reference random variable for analysing the fatigue data coming from tests at different stress ranges, are presented. Next, some desirable properties for a damage measure are discussed and several alternative damage measures are investigated based on these properties. It is shown how several damage measures, such as the Palmgren–Miner number, do not satisfy these properties. On the contrary, the standardized logarithm of the number of cycles, which coincides with the standardized Palmgren–Miner number, a Weibull reference variable and a probability based damage measure are demonstrated to satisfy these properties and to be good alternatives for a damage measure. It is shown that the most convenient damage measures are obtained by assuming that two pieces subjected to different stress level tests suffer the same damage if, at the end of the corresponding tests, they have the same probability of failure. The problem of extending the damage measure below the zero-percentile area (where fatigue failure does not occur) is also analysed. Finally, the damage accumulation problem for non-constant stress range load histories is discussed, and formulae for calculating the associated damage are given. For the sake of illustration, several examples of different load types are also given.