Leaching ratio

The 2eohtes are prepared as essentially bindedess preformed particles. The kaolin is shaped in the desired form of the finished product and is converted in situ in the pellet by treatment with suitable alkaU hydroxide solutions. Preformed pellets of 2eohte A are prepared by this method. These pellets may be converted by ion exchange to other forms such as molecular sieve Type 5A (1). ZeoHtes of higher Si02/Al202 ratios, eg, 2eohte Y, can be obtained by the same method, when sodium metasiUcate is incorporated in the preshaped pellets, or when acid-leached metakaolin is used. 

In most ores, sufficient Fe is already present. For some ores, it is necessary to add metallic iron. In practice, the oxidation potential of the solution can be monitored and controlled using the Fe /Fe ratio. Very high leaching efficiencies with H2SO ate common, eg, 95—98% dissolution yield of uranium (39). If acid consumption exceeds 68 kg/1 of ore treated, alkaline leaching is preferred. The comparative costs of acid, sodium hydroxide, and sodium carbonate differ widely in different areas and are the determining factor. 

The reaction mixture is filtered. The soHds containing K MnO are leached, filtered, and the filtrate composition adjusted for electrolysis. The soHds are gangue. The Cams Chemical Co. electrolyzes a solution containing 120—150 g/L KOH and 50—60 g/L K MnO. The cells are bipolar (68). The anode side is monel and the cathode mild steel. The cathode consists of small protmsions from the bipolar unit. The base of the cathode is coated with a corrosion-resistant plastic such that the ratio of active cathode area to anode area is about 1 to 140. Cells operate at 1.2—1.4 kA. Anode and cathode current densities are about 85—100 A/m and 13—15 kA/m, respectively. The small cathode areas and large anode areas are used to minimize the reduction of permanganate at the cathode (69). Potassium permanganate is continuously crystallized from cell Hquors. The caustic mother Hquors are evaporated and returned to the cell feed preparation system. 

Good rhodium retention results were obtained after several recycles. However, optimized ligand/metal ratios and leaching and decomposition rates, which can result in the formation of inactive catalyst, are not known for these ligands and require testing in continuous mode. As a reference, in the Ruhrchemie-Rhone-Poulenc process, the losses of rhodium are <10 g Rh per kg n-butyraldehyde. 

Reaction experiments were performed at the substrate to catalyst ratios between 250 and 5000 (Table 1). The immobilized catalyst showed a rather constant values of TOP and enantioselectivity in spite of the increase in the S/C ratio, even though these values were slightly lower than those of the homogeneous Ru-BINAP catalyst. After the reaction, the Ru content in the reaction mixture was measured by ICP-AES and was found to be under 2 ppm, the detecting limit of the instrument, indicating the at Ru metal didn t leach significantly during the reaction. These results show that the immobilized Ru-BINAP catalyst had stable activity and enantioselectivity and that the Ru metal complex formed a stable species on the alumina support. 

At the stage of Kuroko mineralization, evolved reacted seawater enriched in Eu, Ca, and Sr formed at low seawater/rock ratio (ca. 1 by mass) and at relatively reduced condition (Eu +/Eu + greater than 1). Selective leaching of Eu, Ca and Sr occurred from the dacitic rocks underlying the Kuroko ores. The hydrothermal solution enriched... 

Fig. 2.43. Graphical illustration of sulfur isotope values of HiS (left axis and. solid line) produced during basalt-seawater interaction at various water/rock ratios. Calculations assume that seawater sulfate is mostly removed as anhydrite, that any residual sulfate is reduced by iron oxidation in reacting basalt, and that there is quantitative leaching of basaltic sulfide and homogeneous mixing of both sulfides. Dashed line...

Figure 21. ( Ra/ Ra)-K/( Ra) diagram proposed by Voltaggio et al. (1995). In this diagram, equivalent to a ( Ra/ °Th)-K/( °Th) diagram, are reported the data resulting from successive leachings of K-rich volcanic rocks from Vulcano (Eolian Islands). For each rock, the data define a straight line, whose intercept on the y-axis gives the ( Ra/ h) ratio of the Th-emiched accessory phase and thus the age of the rock (UCS 2.9 0.4 ka DS 2.1 0.3 ka PLZ 1.5 0.2 ka). K/( Ra) ratios are expressed in weight % K/dpm.g (results from Voltaggio et al. 1995 see text for a detailed explanation).

Figure 5. Histogram Th/U for clinopyroxenes in peridotites and pyroxenites from the Ronda peridotite massif Concentrations were measured by isotope dilution mass spectrometry in acid-leached clinopyroxenes. This histogram shows that pyroxenites do not have larger Th/U ratios than peridotites. Thus, the correlation found between ( °Th/ U) and Th/U cannot be explained by mixing of peridotite and pyroxenite melts as advocated in Sigmarsson et al. (1998). Data from Hauri et al. (1994) and Bourdon and Zindler (unpublished). It can be shown with a simple Student t-test that the two populations are indistinguishable.

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