Toshishige Suzuki

Hydrometallurgical process for recovery of metal values from spent lithium-ion secondary batteries

We report studies on the separation and recovery of metal values such as cobalt and lithium from spent lithium-ion secondary batteries. Effects of leachant concentration, temperature, reaction time and solid-to-liquid ratio on leaching of cobalt and lithium contained in the anode material of the batteries were examined using several reagents such as sulfurous acid, hydroxylamine hydrochloride and hydrochloric acid as leachants. Hydrochloric acid was found to be the most suitable leachant among the three reagents. A leaching efficiency of more than 99% of cobalt and lithium could be achieved when 4 M HCl solution was used at a temperature of 80°C and a reaction time of 1 h. The pH of the final pregnant liquor obtained was around 0.6 and the concentrations of cobalt and lithium were approximately 17 and 1.7 (g l−1), respectively. The cobalt in the leach liquor was extracted selectively and nearly completely with 0.90 M PC-88A in kerosene at equilibrium pH ≈ 6.7 in a single stage at an O:A ratio of 0.85:1. Then the cobalt in the loaded organic phase was recovered as cobalt sulfate with high purity (LiCo < 5 × 10−5) after lithium scrubbing with a dilute hydrochloric acid solution containing 30 g l−1 of cobalt at an O:A phase ratio of 10:1. This was followed by stripping with a 2 M H2SO4 solution at an O:A ratio of 5:1. The raffinate was concentrated and the lithium remaining in the aqueous solution was readily recovered as lithium carbonate precipitate by the addition of a saturated sodium carbonate solution at close to 100°C. The content of cobalt in the lithium precipitate was found to be less than 0.07%. Lithium recovery approached 80%. A flowsheet of the hydrometallurgical process for the recovery of cobalt and lithium from the spent lithium-ion secondary batteries has been established based on the experimental results.

Preparation of porous resin loaded with crystalline hydrous zirconium oxide and its application to the removal of arsenic

Abstract A porous resin loaded with monoclinic or cubic hydrous zirconium oxide was prepared by incorporation of ZrOCl 2 ·8H 2 O into porous spherical polymer beads followed by hydrolysis and hydrothermal treatment of the zirconium salt. Hydrous zirconium oxide appeared to deposit inside the pores with relatively large diameter. The adsorption capacity and distribution coefficients for As(III) and As(V) were determined by batch procedures. The hydrous zirconium oxide-loaded resin (Zr resin) showed a strong adsorption for As(V) at slightly acidic to neutral pH region while As(III) was favorably adsorbed at pH around 9 to 10. The removal of low concentrations of arsenic from the model effluents to meet the demand of Japanese industrial effluent standard (0.1 ppm) was successfully achieved by the column operation packed with the Zr resin. The Zr resin was regenerated by treatment of the column with 1 M sodium hydroxide followed by conditioning with 0.2 M acetate buffer solution. The amount of zirconium leached out during the adsorption and regeneration cycles was negligibly small and the column can be used repeatedly.

Hydrometallurgical process for recovery of metal values from spent nickel-metal hydride secondary batteries

Abstract A completely hydrometallurgical process has been developed for the recovery of metal values such as cobalt, nickel and rare earths from spent nickel-metal hydride (Ni-MH) secondary batteries. Effects of hydrochloric acid concentration, temperature, reaction time and solid-to-liquid ratio on leaching of metals contained in the electrode materials of the batteries were studied. The optimal operating conditions were found to be 3 M HCl at a temperature of 95°C and a 3-h leach time, and it was possible to treat up to 5.5 g of scrap in 50 ml of acid solution where the recoveries 100% of cobalt, over 96% of nickel and 99% of rare earths were achieved. A typical chemical composition of the resulting leach liquor was approximately, in grams per liter, 23.4 Ni, 1.7 Co, 3.4 Fe, 0.72 Zn, 0.46 Al, 1.2 Mn, 4.2 La, 0.26 Ce, 0.82 Pr, 2.6 Nd and 0.074 Sm, as well as 50 Cl. The pH of the solution was around 1.2. The rare earth values can be readily recovered from the leach liquor by the use of a solvent extraction circuit with 25% bis(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene, in which a two-stage counter-current extraction at an O:A ratio of 3:1 at an equilibrium pH of 2.0, a single-stage cobalt scrubbing with 0.3 M hydrochloric acid at an O:A ratio of 22:1, and a stripping operation with 2.0 M hydrochloric acid in one contact at an O:A ratio of 5:1 are involved. A mixed rare earth oxide of over 99% purity was obtained by selective precipitation with oxalic acid, and calcination of the precipitate. The total yield of rare earths approached 98%. The cobalt and nickel in the raffinate are effectively separated by selective extraction of cobalt with 25% TOA in kerosene after concentration (up to [Cl−]≈220 g l−1). Nearly complete recovery of cobalt can be achieved by using a three-stage counter-current extraction at an O:A ratio of 2:1, followed by stripping with a dilute hydrochloric acid solution (pH 2.0) in a single stage at an O:A ratio of 4:1. Subsequently the cobalt in the strip liquor and the nickel remained in the raffinate are separately recovered as oxalates by the addition of ammonium oxalate. A pure cobalt product and a nickel oxalate with a purity close to 99.9% were obtained. The total recoveries of cobalt and nickel were found to be approx. 98% and 96%, respectively.

Recovery of metal values from spent nickel–metal hydride rechargeable batteries

Abstract A hydrometallurgical process is developed for the separation and recovery of metal values such as nickel, cobalt and rare earths from spent nickel–metal hydride (Ni–MH) rechargeable batteries. After removal of the external case, the electrode materials are dissolved in 2 M sulfuric acid solution at 95°C. The resulting liquor contains typically (g l−1), 10.6 Ni, 0.85 Co, 1.70 Fe, 0.36 Zn, 0.21 Al, 0.54 Mn, 1.73 La, 0.10 Ce, 0.33 Pr, 1.10 Nd and 0.032 Sm. The pH is around 0.4. The rare earth values are recovered from the liquor by means of a solvent extraction circuit with 25% bis(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene, followed by precipitation with oxalic acid. A mixed rare earth oxide of about 99.8% purity is obtained after calcination of the precipitate. The total yield of rare earths approaches 93.6%. The cobalt and nickel in the raffinate are effectively separated by solvent extraction with 20% bis(2,4,4-tri-methylpenthyl) phosphinic acid (Cyanex 272) in kerosene. The individual cobalt and nickel are then recovered as oxalates by the addition of oxalic acid. Cobalt and nickel oxalates with purities close to 99.6% and 99.8%, respectively, are obtained. The overall recoveries are over 96% for both cobalt and nickel. A total flowsheet of the process for recovery of rare earths, cobalt and nickel from spent Ni–MH batteries is proposed.

A critical study of the measurement and calibration of circular dichroism.

Abstract A critical study has been made of circular dichroism (CD) measurements at the wavelengths around 500, 290, and 220 nm. Instruments calibrated at 290 nm with (+)-camphor-10-sulfonic acid gave results for molecular ellipticities [θ] showing deviations up to >30%, at both 220 and 490 nm. Older instruments tended to given higher values of [θ] at 490 nm and lower values at 220 nm, probably due to the age of the Pockel cells. A proposal is made to use d -pantolactone and (+)-tris(ethylenediamine) cobalt (III) iodide monohydrate as calibration standards at 220 and 490 nm, respectively, together with (+)-camphor-10-sulfonic acid at 290 nm.

The synergistic extraction of nickel and cobalt with a mixture of di(2-ethylhexyl) phosphoric acid and 5-dodecylsalicylaldoxime

The synergistic extraction of nickel and cobalt from acidic aqueous solutions has been observed with a mixture of di(2-ethylhexyl) phosphoric acid and 5-dodecylsalicylaldoxime. The rates of extraction and stripping were found to be rapid, even for nickel, and stripping of nickel-loaded organic phase was readily achieved by contact with 0.50 M mineral acid. The separation of nickel and cobalt is possible based on differences in stripping behaviors of the two metals.

ADSORPTION CHARACTERISTICS AND REMOVAL OF OXO-ANIONS OF ARSENIC AND SELENIUM ON THE POROUS POLYMERS LOADED WITH MONOCLINIC HYDROUS ZIRCONIUM OXIDE

Adsorption properties for oxoanions of Se(IV), Se(VI), As(III), As(V), and methyl derivatives of As(V) have been examined by the porous polymer beads loaded with monoclinic hydrous zirconium oxide (Zr-resin). The retention of these ions on the Zr-resin has been analyzed using Langmuir model of adsorption. The equilibrium constants and the capacities for above ions have been determined. The equilibrium constants for monomethyl arsinic acid and dimethyl arsinic acid are similar to that of As(V) but the adsorption capacity depends on the number of methyl groups. As(V) and Se(IV) are effectively retained on the Zr-resin from an aqueous solution of acidic to neutral pH region, whereas As(III) is removed from neutral to alkaline solution. The column system packed with the present Zr-resin can quantitatively remove low levels of As(V) and Se(IV) from aqueous solution.

Adsorption and removal of oxo-anions of arsenic and selenium on the zirconium(IV) loaded polymer resin functionalized with diethylenetriamine-N,N,N′,N′-polyacetic acid

A polymer adsorbent in which a Zr(IV)-edta complex analogue is immobilized has been prepared and applied to the removal of oxo-anions of As(III), As(V) and Se(IV). Effective retention of these anions has been demonstrated with the proposed polymer complex system. The adsorption mechanism of oxo-anions onto the Zr(IV)-chelated polymer complex has been investigated using Zr(IV)-edta as the model compound. The formation of mixed complexes with oxo-anions has been exemplified by the isolation of the carbonato complex K2[Zr(CO3)edta].3H2O, the structure of which has been confirmed by X-ray crystallography. NMR study suggests that oxo-anions that form weak or moderate conjugate acids, including those of As(III), As(V) and Se(IV), can form mixed complexes with Zr(IV)-edta using the unsaturated coordination site. However, oxo-anions of strong conjugate acids did not show any appreciable interaction with this complex. According to these observations, retention of oxo-anions on the Zr(IV)-chelated polymer complex has been interpreted by a ligand substitution reaction. The adsorption characteristics of As(III), As(V) and Se(IV) on the Zr(IV)-loaded resin have been examined with respect to the equilibrium adsorption, percentage extraction and the effect of co-existing ions. The adsorption and desorption cycles of the oxo-anions have been demonstrated using a column packed with the proposed resin without any loss of column performance, which indicates the possibility for repeated use.

Chromatographic separation and inductively coupled plasma atomic emission spectrometric determination of the rare earth metals contained in terbium

Abstract The chromatographic separation of rare earth elements (REEs), prior to inductively coupled plasma atomic emission spectrometric (ICP-AES) measurements, using a column packed with 2-ethylhexyl hydrogen 2-ethyl-hexylphosphonate (PC-88A)-loaded polymer resin in order to exclude spectral interferences was examined. A favourable separation of trace amounts of metals (La, Nd and Sm) from a large amount of terbium was achieved simply by elution with dilute hydrochloric acid. Trace lanthanum and neodymium in metallic terbium were determined by separation of the analyte ions from the matrix element followed by ICP-AES analysis.

Chiral molecular patterns of self-assembled ion pairs composed of (R,S), (S)-16-methyloctadecanoic acid and 4,4′-bipyridine

Self-assembled monolayers of stearic acid, (R,S) and (S)-16-methyloctadecanoic acid ion-paired with 4,4′-bipyridine have been observed on a solution–graphite interface by a scanning tunneling microscope (STM) and the observed macro-scale molecular patterns have been interpreted in terms of absolute chirality of the constituent molecule.