Amines circuits

A foaming problem was treated with limited success by antifoam iiyection, frequent activated-carbon r eneration, and reduced MEA circulation. Problem was finalfy solved by using finer filter elements and adding a filter to the lean amine circuit. 

Stage is included to control the level of iron build-up on the organic phase. Amine circuits also often require a regeneration circuit to protonate the extractant ahead of the extraction process. Other amine circuits may use a strong caustic wash to remove very strongly bound impurity species from the stripped organic phase to avoid loss of capacity on recycle of the organic to the extraction circuit. 

The fine mica fraction is deslimed over 0.875—0.147-mm (80—100-mesh) Trommel screens or hydrocylcones, or is separated with hydrosi2ers. The deslimed pulp (<0.589 mm (—28 mesh)) of mica, feldspar, and quart2 is then fed to a froth flotation circuit where these materials are separated from each other either by floating in an acid circuit with rosin amine and sulfuric acid (2.5—4.0 pH), or an alkaline circuit (7.5—9.0 pH) with tall oil amine, goulac, rosin amine acetate, and caustic soda (see Eig. 2). 

A great variety of resia formulations is possible because other thermosets, such as epoxies or acrylates, and reactive diluents, such as o-diaUyl phthalate [131-17-9] triaUyl cyanurate [101-37-17, or triaUyl isocyanurate [1023-13-6J, can be used to further modify the BT resias. The concept is very flexible because bismaleimide and biscyanate can be blended and copolymerized ia almost every ratio. If bismaleimide is used as a major constituent, then homopolymerization of the excess bismaleimide takes place ia addition to the copolymerization. Catalysts such as ziac octoate or tertiary amines are recommended for cure. BT resias are mainly used ia ptinted circuit and multilayer boards (58). 

Elastomers, plastics, fabrics, wood and metals can be joined with themselves and with each other using nitrile rubber/epoxy resin blends cured with amines and/or acidic agents. Ethylene-propylene vulcanizates can also be joined using blends of carboxylated nitrile rubber, epoxy resin and a reactive metal filler (copper, nickel, cobalt). However, one of the largest areas of use of nitrile rubber modified epoxy systems is in the printed circuit board area [12]. 

Various amines find application for pH control. The most commonly used are ammonia, morpholine, cyclohexylamine, and, more recently AMP (2-amino-2-methyl-l-propanol). The amount of each needed to produce a given pH depends upon the basicity constant, and values of this are given in Table 17.4. The volatility also influences their utility and their selection for any particular application. Like other substances, amines tend towards equilibrium concentrations in each phase of the steam/water mixture, the equilibrium being temperature dependent. Values of the distribution coefficient, Kp, are also given in Table 17.4. These factors need to be taken into account when estimating the pH attainable at any given point in a circuit so as to provide appropriate protection for each location. 

Green, J. C. and Donaldson, R. M., The role played by ion chromatography in the assessment of amines for two-phase erosion corrosion control in nuclear electric s steam-water circuits, ]. Chromatogr., 640, 303, 1993. 

Hybertsen MS, Venkataraman L, Klare JE, Whalley AC, Steigerwald ML, Nuckolls C (2008) Amine-linked single-molecule circuits systematic trends across molecular families. J Phys Condens Matter 20(37) 374115... 

Quek SY, Venkataraman L, Choi FU, Louie SG, Hybertsen MS, Neaton JB (2007) Amine-gold linked single-molecule circuits experiment and theory. Nano Lett... 

A partially neutralized aliphatic mono-amine was used (collector CES 109) in the niobium circuit instead of diamine. 

The effects on the dynamics of photo-injected electrons where not systematically studied, despite scattered reports on the influence of amines, which induce surface deprotonation, and lower surface charge with a resulting negative shift in band edge position and an increase in the open circuit potential, Voc [103], The opposite effect is induced by Li+ ions, which intercalate in the oxide structure. Guanidinium ions increase Voc when used as counterions in place of Li+. Other adsorbing molecules that influence both Voc and short circuit current are polycar-boxylic acids, phosphonic acids, chenodeoxycholate and 4-guanidinobutyric acid. 

Tertiary amines are susceptible to oxidation (RsNiO), and some evidence has been found to suggest that oxidation does indeed occur after several months recycling in a uranium solvent extraction circuit [A. W. Ashbrook, unpublished data]. 

Unlike the amine extractants, this compound does not protonate easily and provides excellent selectivity over those metals and metalloids that exist as chloroanions in this medium. Extraction of the latter species becomes significant only above 8 mol dm chloride, as protonation becomes significant. This extractant [Acorga CLX 50], which contains 50% of the active ingredient, has been proposed for an integrated leach, extraction, electrowinning circuit (Cuprex process) [19]. 

The anolyte, containing about 75gdm CD at pFI 2, is fed to a solvent extraction circuit for the separation of Fe—Co and Fe—Ni with a tertiary alkyl amine, dissolved in kerosene. The separation is based on the tendency of the metals to form metal-chloride-amine complexes (Fig. 11.2). At low chloride ion concentration (about 75gdm ), Fe(III) is extracted to the organic solvent, while Co(II) and Ni(II) remain in the aqueous raffinate. If the chloride ion concentration is then increased to about 250 gdm, cobalt is extracted, leaving nickel behind in the raffinate. 

Biochemical lesions that induce depressive syndromes include such classic examples as Parkinson s and Huntington s diseases, especially early in their courses. These disorders involve derangements of central amine systems (i.e., in Parkinson s, there is a disturbance in both dopamine and norepinephrine in Huntington s, dopamine is affected, as well as other nonbiogenic amine neural circuits). Furthermore, antidepressants and ECT, which potentiate central neurotransmission, have effectively relieved depression associated with Parkinson s disease. 

BISMALEIMIDE POLYMERS. These relatively new polymeric materials were developed to serve the increasing requirements for materials of high strength in high-temperature applications. Currently, a high percentage of the bismaleimides produced are used for printed circuit boards (PCBs). The materials usually are cured with aromatic amines and then compression molded into the PCBs. Future uses include aircraft structural components where bismaleimides may prove superior for high-temperature skin surface applications as compared with present epoxy composites. 

Electroless nickel—boron baths use sodium borohydride or dimethyl amine borane [74-94-2] in place of sodium hypophosphite (see Boron COMPOUNDS). The nickel—boron alloy is brittle, highly stressed, and much more expensive than nickel—phosphorus alloys. Nickel—boron is mainly used to replace gold in printed circuit board plating. 

The experimental data for a were compared with theoretical values calculated by means of analogy considerations to electric flow (Ohm s law) [112]. Simple circuit models based on a network of resistors were applied to simulate the cross-type configuration chosen. It could be shown that the calculated values for amin and am3X were in excellent agreement with the experimental data. 

Nitro-4-(trifluoromethyl)-phenol 42 (Scheme 17) in reaction with 2-bromo-2-methyl-propionamide in the presence of cesium carbonate and cesium iodide in acetonitrile afforded 2-hydroxy-2-methylpropionamide 43, apparently via derivative 44 as the intermediate [32]. Amide 44, prepared on a circuitous route, on reduction with borane-dimethylsulfide complex, gave amine 45 as the only isolated product. The parent 2-hydroxy-2-methyl-W-(2-... 

The organic amine extractants are the most commonly used anion exchangers. Secondary amines have been used to recover uranium from leach liquors (GlO) secondary and tertiary amines to recover molybdenum from uranium mill circuits (L13) a primary amine, diethylenetriamine-penta-acetic acid (DTPA) to extract cerium group lanthanides (B6) tri-,V-butylamine-3-methyl-2-butanonc to separate yttrium and rare earth nitrates (G13) tricaprylyl amine (Alamine 336) and methyltrioctyl-ammonium salt (Aliquat 336) to recover vanadium from acidic solutions (A3) and Aliquat 336 to extract vanadium from slightly acidic or alkaline leach liquor (S36). 

Several copper(I) and copper(II) complexes form nuclei for the catalytic deposition of copper or nickel. These include phosphite complexes of Cu such as CuP(OMe)3BH3CN or [Cu(P(OMe)3)4]BPli4 and Cu amine complexes such as [Cu(en)2][BPli4]2 or [Cu(bipy)2][BPli4]2. The complexes are only ultraviolet sensitive, permitting their being handled in dayli t. They are considered useful in printed circuit manufacturing. 

In the processing of mined potash ores, clay in the pulped ore causes higher consumption of collector reagents by adsorption of these, and reduced sylvite recoveries. The clay may be separated from the pulped ore prior to the addition of the amine collector by a desliming decantation, which is a gentle, preflotation collection of the clays in a clay-laden froth. The brine from the clay/brine froth is recycled to the flotation circuit after flocculation of the clay followed by removal of the floe in a thickener [22]. 

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