Alkali Zinc Research Articles

Viscosity and Softening Behavior of Alkali Zinc Sulfophosphate Glasses

We report on the softening properties and viscosity of glasses from the system ZnO–Na2O–SO3–P2O5 for low‐temperature sealing applications. Up to a ratio of network‐forming ions PO43−:SO42− of about 2:1, a gradual substitution of P2O5 by SO3 results in decreasing glass transition and softening temperatures. At the same time, decreasing kinetic fragility is observed, noteworthy even for decreasing the total amount of network former from 44 at.% to 39 at.%. Thermomechanical and calorimetric analyses reveal a distinct SO42−‐promoted relaxation phenomenon at temperatures significantly below the macroscopic glass transition temperature, which is interpreted as a result of the formation of an increasingly interconnected assembly of SO42− and PO43− units with increasing SO3 content.

Recovery of Zinc by LIX 984N‐C from Electroplating Rinse Bath Solution

The development of a complete solvent extraction process at the laboratory scale for recovering zinc from the zinc electroplating first rinse bath solution (alkali solution) containing ∼1.9 g/L zinc (ZEFRBS) by a solvent extraction route using LIX 984N‐C, which is a new SX reagent developed by Cognis, and dissolved in commercial kerosene was investigated. By using LIX 984N‐C, an electrolyte from ZEFRBS with ∼12 g/L zinc content, which was addable to the alkali zinc electroplating bath, was generated by 10 vol.% LIX 984N‐C in commercial kerosene at the O/A ratio of 1/4 and equilibrium pH value of 8.00 ± 0.05 with a two‐stage countercurrent extraction, and stripping of the loaded organic by a strip solution with 150 g/L sulfuric acid and with the O/A ratio of 1.5 at a two‐stage countercurrent stripping process. A new complete flow sheet of 10 vol.% LIX 984N‐C process for the recovery of zinc from ZEFRBS has been demonstrated.

Thermal Behavior of Alkali Zinc Phosphates

Alkali zinc phosphates Na2ZnP2O7, K2ZnP2O7, LiNaZnP2O7, LiKZnP2O7, NaKZnP2O7, and Li12Zn4(P2O7)5, which can be prepared both by the solid-phase synthesis and through crystallization from a glass, are studied using high-temperature X-ray powder diffraction. The unit cell parameters as functions of the temperature in the range 20–700°C are analyzed, and the linear anisotropic thermal expansion coefficients are determined. The majority of these compounds are characterized by strong anisotropy of thermal expansion. It is found that the LiKZnP2O7 compound exists in two polymorphic modifications, namely, the low-temperature monoclinic modification and the high-temperature orthorhombic modification.

Mixed mobile ion effect in fluorozincate glasses

The mixed mobile ion effect has been investigated for the first time in zinc fluoride glasseswhere in addition to alkali cations fluorine anions also participate in the diffusion process,unlike mixed alkali oxide glasses. The minimum in the conductivity, conductivity relaxationfrequency, crossover frequency and decoupling index indicates the existence of the mixedmobile ion effect in these fluoride glasses. It has been observed that the non-exponentialparameter and the frequency exponent are independent of temperature. It has beenestablished that alkali ions and fluorine anions exhibit lower dimensionality of theconduction pathways in mixed alkali zinc fluoride glasses than that in the single alkalilithium based zinc fluoride glasses while they are migrating. From the scaling of theconductivity spectra, it has been established that the relaxation dynamics inmixed alkali zinc fluoride glasses is independent of temperature and composition.

Integrated Electroplating System Modeling and Simulation for Near Zero Discharge of Chemicals and Metals

The optimality of design and operation of an electroplating system determines largely coating quality, productivity, and waste reduction efficiency. Industrial practice shows that, in a usual operation, the solution loss from an electroplating unit through drag-out can be as high as 30% of overall consumption. This has dramatically increased operating cost as well as waste treatment cost. On the other hand, plating quality in terms of coating thickness on workpieces is always a concern in plants. To improve the economic and environmental performance, a key step is to have a deep understanding of the system. Model-based simulation has proven to be a cost-effective approach along this venue. This paper introduces a fundamental-based general modeling methodology for characterizing an integrated electroplating system that consists of a plating unit and a solution recovery subsystem. The methodology allows detailed system analysis and complete process information integration, which will be crucial for optimal design and operation of a closed-loop electroplating for prevention of plating solution loss and assurance of coating thickness on workpieces. A case study on an alkali zinc electroplating system will demonstrate the efficacy of the model-based design and operation approach.

Decontamination of Zincate Solutions Using Calcium Hydroxide in a Fluidised Bed Reactor

SUMMARYThis article deals with the decontamination and utilisation of waste water. The effectiveness and conditions for the removal of Zn(II) from diluted alkali zinc electroplating bath solutions in flow-rate regime have been investigated. A cheap and simple decontamination route is proposed using the fluidised bed reactor with Ca(OH)2. The advantage of this method is that up to 98% of Zn(II) can be precipitated as a fine crystalline recyclable material—CaZn2 (OH) 6 2H2O with small amount of ZnO. The industrial scheme of this process using lime is proposed.

Crystal Structures of Na2ZnP2O7, K2ZnP2O7, and LiKZnP2O7 Phases in the M2O–ZnO–P2O5 Glass-Forming System (M = Li, Na, and K)

The crystal structures of Na2ZnP2O7 and K2ZnP2O7 are determined from X-ray powder diffraction data. The structure of LiKZnP2O7 is determined using a single-crystal sample. In the alkali zinc phosphates studied, the Zn2+ cation is coordinated by four oxygen atoms of the phosphate tetrahedra. In the first two compounds, the [ZnP2O7]2– anion has the form of a sheet consisting of Zn and P oxygen-containing tetrahedra that involves only five-membered rings. In the LiKZnP2O7 structure, the zinc phosphate anion of the same composition has the form of a three-dimensional skeleton with a three-dimensional system of channels. These channels are linked via six-membered, eight-membered, and ten-membered rings. The atomic coordinates and interatomic distances are reported.

Formation of radiation colour centres in zinc alkali borosilicate glass

Formation of radiation colour centres in zinc alkali borosilicate glass

The role of alkalis and conserving resources in blast-furnace smelting

In ferrous metallurgy, the potential for conserving resources is often determined by the behavior of the impurity elements in metals production. This behavior may be highly complex, and its features may be interpreted differently by different experts. For example, the presence of zinc and alkali metals in the blast-furnace charge is known to result in excessive coke consumption, a reduction in the productivity of the furnace, an increase in the yield of top dust, shortening of the campaign, and in some cases to complete destabilization of the smelting operation. In choosing a technology for blast-furnace smelting, accounting for the entry of alkali metals and zinc into the furnace is one of the most important factors that determines the expediency of controlling the heat “from the top” or “from the bottom” features of the slag formation process, the gasdynamics of the smelting operation, and other characteristics.

Water-related IR absorption spectra for alkali zinc pyrophosphate glasses

The water-related first-order IR absorption spectra of zinc alkali pyrophosphate glasses in the 1400–4000 cm −1 range are investigated. These spectra are shown to contain much greater number of spectral features than the spectra of silicate glasses. The quantitative treatment of spectra obtained is conducted with the dispersion analysis version using the convolution analytical model for the complex dielectric constant. The water-related species in glasses under study are shown to be both the bound hydroxyl group participating in the hydrogen bonding and the H 2O molecule. The corresponding spectral bands are resolved and their frequencies are compared to those in the spectra of water-containing crystals. The stretching mode of bound hydroxyl is shown to be split into a series of components in the 1600–3000 cm −1 range, which is interpreted in terms of the multi-site effect. The occurrence of the multi-site effect for the impurity-related mode is assumed to indicate the phonon-like nature of this mode and non-uniform distribution of the bound hydroxyl groups in the glass samples. The stretching modes of the H 2O molecule are shown to result in several bands in the 2800–3500 cm −1 range.

Multi-site effect in the IR spectra of various inorganic glasses: experimental evidence and structural reasons

Data on the IR spectra of various glasses are reviewed and the spectra of glasses such as vitreous barium metaphosphate, alkali zinc pyrophosphate glasses, and binary borate glasses are subjected to an additional quantitative treatment. A multi-band pattern in the range of the asymmetric stretching modes is shown to occur in the spectra of these glasses. The main reason for the splitting of the asymmetric stretching modes of basic structural groups is shown to be a multi-site effect due to the occurrence of two or more translationally non-equivalent positions of structural groups in the regions of phonon localization. Investigation of the relative intensities of the spectral components originated from the same stretching mode as a function of glass composition is suggested as a possible tool for the study of subtle features of glass structures.

Spectroscopic investigations of Dy 3+ ions in borosulphate glasses

Spectroscopic investigations on optical absorption spectra of Dy 3+ ions in zinc borosulphate (ZnBS:ZnSO 4·7H 2O + B 2O 3) and alkali zinc borosulphate (RZnBS : R 2SO 4+ZnSO 4·7H 2O+B 2SO 4=Li 2SO 4· H 2O, Na 2SO 4 or K 2SO 4) glasses have been carried out. The observed spectra have been analysed in terms of a parametrized model Hamiltonian consisting of 20 interaction parameters of atomic nature. The squared reduced matrix elements, | U λ | 2 ( λ = 2,4,6) for all the 4f 9(Dy 3+) intermanifold J → J′ transitions lying upto 30 000 cm −1 are presented. Using Judd-Ofeltlt theory, intensity parameters have been evaluated which are inturn used to predict various spectroscopic properties of fluorescent levels of Dy 3+ ions in borosulphate glasses. The spectroscopic parameters of Dy 3+ ions in borosulphate glasses are compared to the values of fluoride glasses.

Optical properties of Sm 3+ ions in zinc and alkali zinc borosulphate glasses

Optical absorption spectra are presented for Sm 3+ ions in zinc and alkali zinc borosulphate glasses at room temperature. The absorption bands, responsible for various transitions, are assigned and analysed in terms of a parametrized model Hamiltonian ( H FI). Energy levels and reduced matrix elements calculations were carried out using the complete 198 SLJ basis set for the 4f 5(Sm 3+) configuration. From optical absorption measurements and using the Judd-Ofelt theory, radiative properties for fluorescent levels of Sm 3+ ions have been predicted. Variation of the energy parameters, intensity parameters and radiative properties of Sm 3+ doped glasses is examined.

Melt crystallization of zinc alkali phosphate glasses

Melt crystallization of two zinc alkali phosphate glasses was studied with X-ray diffraction (XRD) experiments to accelerate efforts to melt process these glasses with organic polymers. The inorganic glasses differed markedly in chemical durability (water sensitivity) and crystallization rates. They were studied at room temperature prior to and after melt processing with XRD experiments and in situ at melt temperatures without flow in a novel differential scanning calorimeter/XRD apparatus. The glasses were found to be amorphous at room temperature and semi-crystalline above their glass-transition temperatures. Higher temperatures and shear (mixing) rates increased the crystallization rate of the glasses. The non-durable (water-sensitive) glass was observed to contain significant levels of crystalline matter after melt processing at 400°C. This process-induced crystallization of the glasses must be controlled, possibly during processing and/or glass formulation, otherwise it may lead to formation of unwanted phase-separated defects in the glass. If high levels of the crystalline matter are present during melt processing, they may lead to irreversible plugging of the processing equipment.

IR fundamental spectra and structure of pyrophosphate glasses along the 2ZnO·P 2O 5–2Me 2O·P 2O 5 join (Me being Na and Li)

The IR reflection spectra of mixed zinc alkali pyrophosphate glasses in the broad frequency ranges are reported and the quantitative treatment of these with a version of the dispersion analysis method was conducted based on the specific analytical model of the complex dielectric constant of glasses. Numerical data on the optical constants, band frequencies, and band intensities are calculated. Results obtained are interpreted in terms of vibrations of the (PO 3) 2− and (PO 2) − terminal groups, (PO 4) 3− anion, and P–O–P bridge. The presence of all these groups in the structures of glasses under study is confirmed and the formation of the (P 3O 9) 3− ring metaphosphate anion rather than the chain polymeric phosphate anions is suggested. The gradual decrease in the width of the anion distribution toward the pyrophoshate anion with the Me 2O for ZnO substitution is also confirmed. It is shown that this decrease determines the IR spectrum variations observed in the 0 to about 27 mol% Na 2O composition range. The amounts of the (PO 4) 3− and (P 3O 9) 3− anions are shown to become negligible in the structures of glasses with Na 2O content greater than 30 mol%, and the IR spectrum variations observed in the 27–45 mol% Na 2O composition range are shown to be mostly due to the intensity redistribution from the low-frequency component of the asymmetric stretch of the (PO 3) 2− terminal group to the high-frequency component of the same stretch.

Judd-Ofelt intensity analysis and spectral studies of Pr(III) ions in alkali zinc borosulphate glasses

Judd-Ofelt parameters for Pr 3+ ions in zinc borosulphate glass (ZBS) and alkali zinc borosulphate glasses (RZBS, R = Li, Na, K or Gd) were derived from the intensities of the integrated absorption bands. The radiative transition probabilities A, radiative lifetimes τ r, branching ratios β R and integrated emission cross sections σ a were calculated for the excited states 3P 0, 3P 1 and 1D 2. The resulting spectroscopic parameters are compared with the corresponding reported values.

Electron paramagnetic resonance and optical absorption spectra of Fe(III) ions in alkali zinc borosulphate glasses

Electron paramagnetic resonance (EPR) and optical absorption studies have been made for Fe(III) ions in alkali zinc borosulphate (R 2SO 4-B 2O 3-ZnSO 4, R = Li, Na, K or Cs) glasses. Two resonance lines are observed near g = 4.2 and g = 6.4 in the EPR spectra for all the Fe(III) ion-doped alkali zinc borosulphate glasses. The EPR spectra at different temperatures (123 K to 423 K) for Fe(III) ions doped in K 2SO 4 ? B 2O 3 ? ZnSO 4 glass were measured. It is observed that the peak-to-peak widths ( ΔH pp) of the resonance line at g = 4.2 are independent of the temperature between 123 and 423 K, whereas the spin-susceptibilities decrease with increasing temperature. The optical absorption spectrum of 1 mol% Fe(III) ions in a glass sample of 10K 2SO 4 · 40ZnSO 4 · 49B 2O 3 at 300 K has five bands characteristic of Fe(III) ions in octahedral symmetry. The crystal field parameter, Dq, and the Racah interelectronic repulsion parameters, B and C, have been calculated.

Optical properties of Er3+ ions in zinc borosulphate glasses

AbstractThe optical properties of Er3+ ions in zinc borosulphate (ZnSO4 · 7 H2O + B2O3) and alkali zinc borosulphate (R2SO4 + ZnSO4 · 7H2O + B2O3, R2SO4 = Li2SO4 · H2O, Na2SO4, or K2SO4 and Gd2(SO4)3 · 8H2O) glasses are reported. The assigned energy level data of Er3+(4f11) in borosulphate glasses are analyzed in terms of a parametrized model Hamiltonian and in turn satisfactory eigenvalues and eigenvectors for intensity analyses are obtained. The Judd‐Ofelt theory has been applied to predict various spectroscopic parameters for the fluorescent levels of Er3+ : borosulphate glasses and these results are compared and discussed with similar results.

Melt rheology of zinc alkali phosphate glasses

The melt rheology of two zinc alkali phosphate glasses was studied with oscillatory flow experiments to accelerate efforts to melt process them with organic polymers. The glasses differed markedly in chemical durability and melt viscosity. Melt viscosities were time independent at temperatures near their glass transition temperature. The ω dependence of the complex viscosity η* conformed excellently to predictions, η*(ω)=η0/(1+iωτ), for Hookean dumbbells. Fit parameters η0 and τ were used to estimate a melt viscosity–average molecular weight M using a model reported by Ferry and co‐workers [J. Applied Phys. 26, 359 (1955)]. Arrhenius activation energies ΔH‡ for viscous flow were consistent with those traditionally found for inorganic glasses. At higher temperatures, the melt viscosity of both glasses increased monotonically with time. The viscosity increase was exponential at long times, and the transition time to the exponential dependence was found to be strongly dependent on the shear strain. The steep viscosity rise is expected to cause significant processing challenges. Sample crystallization is thought to be responsible for this behavior.

Identification of organic corrosion inhibitors suitable for use in rechargeable alkaline zinc batteries

Inhibition of the corrosion of zinc in aqueous alkali by various organic compounds has been tested. The rates of hydrogen evolution due to the metal corrosion in these inhibitor environments have been monitored at 25 °C for a number of days. Except for a few of the tested compounds, all inhibited zinc corrosion to varying degrees. Inhibitor performance under electrochemical conditions has been checked for selected compounds that showed appreciable corrosion inhibition in the previous test. Thus zinc polarization is followed with and without these inhibitor environments under potentiostatic conditions. Corrosion potential and current density have been observed to play vital roles in determining suitable performance of inhibitors under battery situations. Inhibitor environments where zinc has produced nearly the same corrosion current density as in the standard (corrosion current density without an inhibitor) have performed well in battery situations. In such cases improved single and accumulated cycle capacities have been recorded in battery situations.