Distribution Coefficients Of Co Research Articles

Distribution of Co, Fe, Ni, and precious metals between blister copper and white metal

ABSTRACT The distribution coefficients of Co, Ni, Ag, Au, Pd, and Fe at low concentrations between liquid copper and molten white metal (low-iron copper matte, ‘Cu2S’) were investigated experimentally as a function of temperature (1250–1350°C) and SO2 partial pressure (0.01–1 atm). The experimental technique involved samples equilibration at controlled temperature and gas atmosphere, followed by quenching and subsequent elemental analysis of equilibrium phases with electron probe X-ray microanalysis and laser ablation-inductively coupled plasma-mass spectrometry. The distribution coefficient of silver, nickel, gold and palladium between liquid copper and white metal indicated that they favour the blister copper whereas cobalt and iron distribute more to the white metal. The distribution coefficient of nickel, e.g. increased from 2.1 at 0.1–1.0 atm PSO2 and 1250°C to 3.2 at 1350°C. The distribution coefficients were only slightly dependent on temperature. The relatively strong dependence of the distribution coefficient of cobalt on PSO2 was discussed.

Single-crystal solidification of new Co–Al–W-base alloys

Solidification processing of new high-temperature Co–Al–W-base single-crystals has been investigated. Single-crystal bars with compositions of Co–9.4Al–10.7W, Co–8.8Al–9.8W–2Ta and Co–7.8Al–7.8W–1.5Ta–4.5Cr (at%) were successfully grown with a conventional Bridgman process. Helical grain selectors resulted in [001] dendritic growth with primary dendrite arm spacings in the range of 278–364 μm. Segregation of constituent elements in the dendritic structure was very limited, compared to Ni-base single-crystals. Concentration profiles obtained by electron microprobe and analyzed via the Scheil equation indicate distribution coefficients for Co, Al, W and Cr that are close to 1. The distribution coefficient of Ta was approximately 0.6, indicating preferential segregation to the liquid during solidification. These observations collectively suggest that convective instabilities and freckle formation are unlikely to occur during solidification of single-crystals of this new class of high strength Co–Al–W-base alloys.

Trace element partitioning between coexisting biotite and muscovite from metamorphic rocks, Western Labrador: structural, compositional and thermal controls

Coexisting biotite and muscovite in ten metapelitic and quartzofeldspathic rocks from western Labrador have been analyzed by electron microprobe for major and minor elements and by a laser ablation microprobe coupled to ICP-MS (LAM-ICP-MS) for selected trace elements—Li, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Hf and Ta. The samples have experienced a single prograde Grenvillian metamorphism ranging from 490 to 680°C and from 7 to 12 kbar. The trace element compositions of coexisting micas in the metamorphic rocks are used to assess the effects of crystal structure, major element composition and temperature on the partitioning of each element between biotite and muscovite. Overall, trace element distributions are systematic across the range of metamorphic grade and bulk composition, suggesting that chemical equilibrium was approached. Most distribution coefficients (biotite/muscovite) show good agreement with published data. However, distribution coefficients for Co and Sr are significantly different from previous determinations, probably because of contamination associated with older data obtained by bulk analysis techniques. The sequence of distribution coefficients is governed mainly by the ionic radii and charges of substituting cations compared to the optimum ionic radius of each crystallographic site in the micas. In particular, distribution coefficients exhibit the sequence Cr 3+ (0.615 Å) > V 3+ (0.64 Å) > Sc 3+ (0.745 Å) in VI-sites, and Ba 2+ (1.61 Å) > Sr 2+ (1.44 Å) and Cs + (1.88 Å) > K + (1.64 Å) > Rb + (1.72 Å) > Na + (1.39 Å) in XII-sites. The distributions of Li, Sc, Sr and Ba appear to be thermally sensitive but are also controlled by major element compositions of micas. V and Zr partitioning is dependent on T and may be used to cross-check thermometry calculations where the latter suffer from retrograde re-equilibration and/or high concentrations of Fe 3+. The ranges and dependence of distribution coefficients on major element compositions provide important constraints on the values that can be used in geochemical modeling.

High-Temperature solutions of the (0.4Na 2O — 0.6B 2O 3 — BaO — ((6 − x)Fe 2O 3 + xCoSnO 3) System. Crystallization regions of BaFe 12 − (x + y)Co xSn yO 19

In this work, high-temperature solutions of the (0.4Na 2O-0.6B 2O 3)-BaO -((6 − x)Fe 2O 3 + xCoSnO 3) system have been investigated. The concentration and temperature regions for the crystallization of BaFe 12 − (x + y)Co xSn yO 19 for four different degrees of cobalt and tin substitution −Fe (Co + Sn) = 12 0 , 11 1 , 10 2 and 9 3 - have been established. Using six compositions for each one of the above mentioned cases, hexaferrite single crystals have been grown by spontaneous nucleation. The volatility and the creeping of these twenty four solutions as well as the habit and distribution coefficients of Co 2+ and Sn 4+ of the single crystals obtained were also discussed. On the basis of these results, suitable solution compositions for the growth of Co 2+ + Sn 4+ substituted barium M-hexaferrites have been proposed.

海水中における放射性コバルトと溶存有機物質との相互作用に関する研究

The interaction of radiocobalt with glycine, alanine or aspartic acid dissolved in seawater was investigated under laboratory conditions by means of adsorption on Chelex 100 solvent extraction with dithizone or gel filtration chromatography. The results also were compared with those in freshly prepared or stored culture filtrates of chlorella, fishpond and offshore seawaters in which ionic radiocobalt was spiked, respectively. The distribution coefficients for Co in Chelex 100 and the extraction rates (%) of Co with dithizone in carbon tetrachloride decreased more greatly with time in the presence of the amino acids than in the control. The inhibitory effect of glycin on the adsorption of Co on the Chelex 100 was smaller than that of alanine or aspartic acid. In the fishpond and offshore seawaters or freshly prepared chlorella culture filtrate, the distribution coefficients for Co in Chelex 100 were somewhat greater than in the control, while no significant difference was observed in dithizone extraction. The results of Sephadex G-10 gel filtration chromatography for Co showed that the higher molecular species of Co associated with the amino acids occurred after several days ageing and then increased together with decreasing in the lower molecular species.

Chemical equilibration of the Earth's core and upper mantle

The oxygen fugacity (fO 2) of the Earth's upper mantle appears to lie somewhat above that of the iron-wüstite buffer, its fO 2 is assumed to have been similar to the present value at the time of core formation. In the upper mantle, the Fe-rich liquid protocore that would form under such conditions of fO 2 at elevated temperatures would lie predominantly in the system Fe-S-O. Distribution coefficients for Co, Cu, Ni, Ir, Au, Ir, W, Re, Mo, Ag and Ga between such liquids and basalt are known and minimum values are known for Ge. From these coefficients, upper mantle abundances for the above elements can be calculated by assuming cosmic abundances for the whole Earth and equilibrium between the Fe-S-O protocore and upper mantle. These calculated abundances are surprisingly close to presently known upper mantle abundances; agreements are within a factor of 5, except for Cu, W, and Mo. Therefore, siderophile element abundances in the upper mantle based on known distribution coefficients do not demand a late-stage meteoritic bombardment, and a protocore formed from the upper mantle containing S and O seems likely. As upper mantle abundances fit a local equilibrium model, then either the upper mantle has not been mixed with the rest of the mantle since core formation, or else partition coefficients between protocore and mantle were similar for the whole mantle regardless of P, T, and fO 2. The latter possibility seems unlikely over such a P-T range.

Adsorption of Cadmium and Cobalt on Montmorillonite as a Function of Solution Composition

AbstractAdsorption of Co2+ and Cd2+ on Wyoming montmorillonite was studied by the batch equilibration technique, as a function of salt concentration (0.01–4 M NaCl and NaNO3), pH (5.0–6.5), adsorbate concentration (trace-10−2 moles/liter), and presence of complexing ions. Comparison was made with the adsorbability of Sr2+, known to follow simple ion-exchange equations. The distribution coefficients for Co and Cd in noncomplexing media varied with salt concentration (from ∼500 liters/kg in 0.01 M Na+ to ∼10 liters/kg in 1 M Na+; pH = 5), but to a lesser extent than that of Sr. Adsorbability varied also with pH (∼1 order of magnitude/pH unit), especially at high ionic strength, compared to a negligible pH effect on Sr. The distribution coefficients of Cd and Co decreased with increasing loading on the clay at a very low percentage (0.2%) of the ion-exchange capacity compared to Sr (20%). These data suggest two classes of sites participating in the adsorption of Cd and Co.The adsorbability of Cd in highly concentrated chloride solution (>1 M) was less than 1 liter/kg, presumably because of the chloride complex formation. This effect increased with increasing pH. The low adsorbability of Cd on montmorillonite from concentrated NaCl solution is promising with respect to its use as a tracer for monitoring flow through formations containing montmorillonite.

Electrical conduction and diffusion studies in NH 4H 2PO 4 and KH 2PO 4 single crystals

Electrical conduction (dc) studies are made with pure and cobalt(II)-doped single crystals of NH 4H 2PO 4 and KH 2PO 4. The effect of the dopant concentration on the enthalpy for the migration of protons and the enthalpy for the rotation of the H 2PO 4 group have been studied. It is suggested that proton migration occurs through a synchronous phosphate rotation mechanism. Tritium diffusion studies in KDP and 32PO 4 diffusion in ADP crystals have been made. The mechanisms for the conduction and diffusion processes are found to be different in nature. The distribution coefficients of Co(II) dopant in ADP (2.92 × 10 −3) and KDP (1.14 × 10 −3) are calculated. The following enthalpy values are obtained. KDP (eV) ADP (eV) Enthalpy for the migration of protons 0.01 ± 0.01 0.15 ± 0.02 Enthalpy for the rotation of phosphate group 0.71 ± 0.01 0.66 ± 0.01 Enthalpy for T-diffusion 0.14 ± 0.01 — Enthalpy for 32PO 4 diffusion — 0.24 ± 0.01

Interaction of radionuclides with organic matter dissolved in seawater. Interaction of radiocobalt with some amino acids.

The interaction of radiocobalt with glycine, alanine or aspartic acid dissolved in seawater was investigated by means of adsorption on Chelex 100, solvent extraction with dithizone or gel filtration chromatography. Although the distribution coefficients of Co on Chelex 100 decreased gradually with ageing even in the absence of organic matter, much more decreases were observed in the presence of the amino acids. The distribution coefficients on the resin reached equilibrium states in about 20 days. The extraction of cobalt with dithizone in carbon tetrachloride was also inhibited in the presence of the amino acids. Alanine and aspartic acid showed a similar interfering tendency in both adsorption on Chelex 100 and dithizone extraction, while glycine inhibited dithizone extraction more than adsorption on Chelex 100. From the fractionation of Co by Sephadex G-10 gel filtration chromatography, the higher molecular species of Co associated with the amino acids occurred after several days ageing and then increased together with decreasing in the lower molecular species.