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Nitric acid leaching of waste plasma display panel (PDP) electrode scrap was investigated as a part of development for a pre-treatment process to increase Ru content in the scrap. Leaching performance was evaluated in terms of different experimental parameters such as nitric acid concentration, reaction temperature and time. An aqueous nitric acid leaching solution with a concentration range of 1.5 M–3.0 M at 60 � C and 1.5 M–4.2 M at 75 � C demonstrated as the most effective condition for the selective removal of Pb and Ba from waste PDP scrap powders with about 90% of Pb and 95% of Ba leached in 30 min. The rate of dissolution decreased after a certain level of HNO3 concentration due to formation of Pb(NO3)2 which has limited solubility in the aqueous solution. Other impurities such as Bi, Zn, Ag and Co were dissolved at the level of 75%–90% at all the leachant concentrations, leaching time and temperatures applied, while Si, Al and Fe showed a poor leachability with only 7%, 30% and 40% dissolution, respectively. Ru and Zr were almost insoluble in an aqueous nitric acid solution. The total concentration of Ru in the undissolved residue (27.96%) of the scrap powder after nitric acid leaching was brought up to 93.8% from the initial concentration (14.43%) of the scrap in the final process. The precipitation behavior of Pb(NO3)2 as well as the solubility of SiO2 were also investigated. [doi:10.2320/matertrans.M2010417]

A basic study for the recovery of tin(Sn) from the scraps or plating sludges by a hydrometallurgical process was carried out. Tin was leached out by hydrochloric acid solutions and then separated from the mixed solution of co-leached miner metals such as, As, Sb, Bi, Cu, Zn and Pb for making high purity metal. A solvent extraction process was followed for the separation of tin and other minor metals from hydrochloric acid solution using TBP (tri-n-Butylphosphate) as the extracting reagent. Optimum conditions for the separation process were obtained using separation factors of tin versus each metal impurities derived at various concentrations of hydrochloric acid and sodium chloride in aqueous solution, and TBP in the organic solution. Scrubbing for metal impurities from the loaded organic solution was studied with different HCl concentrations. The study showed that Pb, Bi, Cu, Zn and Sb were quantitatively removed by scrubbing with 8.0 mol/L HCl from the organic phase after extracted in 6.0–7.0 mol/L HCl solution; As with 4.0 mol/L HCl solution from the organic phase after extracted in 3.0 mol/L HCl solution. From the integrated separation experiment by the simulate solution at 25 � C, 1.0 of O/A, and one stage contact at each extraction and purification step, the purity of finial Sn strip solution was 98.9% and the recovery of Sn was 67.9%. [doi:10.2320/matertrans.M2011142]

Solvent extraction experiments of Gd from chloride solution with PC88A were conducted at different extraction conditions. Solvent extraction reaction was identified from the experimental results using a graphical method, and the corresponding effective equilibrium constant was determined by analyzing the ionic equlibria in a GdCl 3 solution. In the experimental ranges investigated in this study, i.e., [GdCl 3 ] ≤ 0.3 kmol/m 3 , [PC88A] o r < 3.0 kmol/m 3 and initial pH ≤ 2.3, solvent extraction reaction or Gd with PC88A and the corresponding effective equilibrium constant were obtained as follows Gd 3 + + 2H 2 A 2 . o r g = GdA 3 HA o r g + 3H + , K e x , e f f = 2.8 x 10 - 1 .

A kinetic study on the electrodeposition of Fe-Zn-P ternary alloys onto steel in chloride solutions was carried out using a rotating disc geometry. Mass transfer through diffusion layer controlled the deposition rates of zinc onto steel, and those of iron and phosphorus were controlled by the rates of both electrochemical reaction and mass transfer. The zinc content in the Fe-Zn-P alloy increased with stirring speed and voltage. However, iron content in the Fe-Zn-P alloy decreased with speed and voltage. The phosphorus content is almost constant with respect to stirring speed in the lower voltage range but decreased slightly with stirring speed in the higher voltage range.