A horizontal pulsed solvent extraction column (HPC) has great potential in replacing vertical pul'sed columns (VPC) in the separation of heavy elements in the nuclear industry. Published work examining the performance of the HPC suggests that the mass transfer efficiency for this column is comparable to the VPC, but information on the hydrodynamic characteristics of the HPC is sparse. This paper describes the flow characteristics of the HPC and presents experimental results and correlations for flooding conditions and holdup of the dispersed phase. Correlations obtained for the HPC for these hydrodynamic parameters are compared to published results for the VPC.La colonne pulsCe horizontale (HPC) servant B I'extraction de solvants montre un fort potentiel pour remplacer les colonnes puldes verticales (VPC) dans la sCparation des ClCments lourds dans I'industrie nuclCaire. Les travaux publits examinant la performance de la colonne horizontale suggkrent que I'efficacitC du transfert du matikre pour cette colonne est comparable B celle de la colonne verticale, mais les donnCes sur les caractkristiques de la HPC sont rares. On dicrit dans cet article les caractiristiques d'Ccoulement de la HPC et on prCsente des risultats expkrimentaux et des corrtlations pour des conditions d'engorgement et la rCtention de la phase disperste. Les corrClations obtenues pour la colonne horizontale pour ces parametres hydrodynamiques sont comparCes aux rCsultats publits pour la colonne verticale.Keywords: solvent extraction equipment, pulsed columns, flooding, holdup. olvent extraction is used in the nuclear industry to 417 THE

About 150 flotation tests were done on Elliot Lake ore with 15 reagents as collectors in order to screen and choose an attractive collector for uranium flotation. Several variables were studied including pH, conditioning time and mode of collector addition. The tests were done in a Denver or Agitair subacration cell. The particle size of the ore was kept at 85% below‐325 mesh. Three reagents (Kelex 100, TOPO, and cupferron) were identified as having the most promise. The best results were obtained with cupferron, where 93‐95% of the uranium was recovered in 25‐30% of the mass of original ore. Radium in the tails varied between 15 and 30 pCi/g depending on the mass of uranium floated. Radium was recovered in proportion to uranium in the tests done at neutral pH. The preconcentration results obtained by flotation alone were comparable to those obtained by Raicevic of CANMET using pyrite flotation and wet high intensity magnetic separation of uranium. The consumption of cupferron was 4 kg/Mg ore for each flotation stage. This was 10‐15 times larger than the collector usage in conventional oxide flotation. This scheme did not require other reagents as depressants, activators or modifiers. Reproducibility was good and similar recoveries were obtained with fresh or old ores, and with distilled or mine water. The selectivity of cupferron for uranium in the ore studied was outstanding.

Perforated Plate Ont. L8S 4L7The axial mixing and countercurrent mass transfer characteristics of a 5 cm diameter extraction column agitated by vibrating perforated Teflon plates have been investigated. The dispersed phase was an organic liquid (usually kerosene) and the continuous phase was water. Axial mixing was measured in both phases using pulse tracer techniques; in the continuous phase the axial mixing was estimated to have a significant effect on mass transfer, but axial mixing in thc dispersed phase had a negligible effect. Mass transfer was measured for several different solutes; n-butyric acid. benzoic acid and phenol. The overall heights of a transfer unit (cont. phase) were in the order of 10-20 crn for the organic acids but higher for transfer of phenol from very dilute solutions. The characteristics of the vibrating plate column have been compared with those of other types of extractor and suggestions are made for further development..~ ~ ~~ On a CtudiC les caracteristiques du melange axial et du transfert de matiere a contre-courant d'une colonne d'extraction de 5 cm de diamktre agitee par des plateaux de Teflon perforts vibrants. La phase dispersie est un liquide organique (generalement du kerosene) et la phase continue de I'eau. Le mtlange axial a it6 mesure dans les deux phases par des techniques de traqage pulse; dans la phase continue, on a trouve que le melange axial avait un effet significatit sur le transfert de matikre, tandis que dans la phase disperske, I'effet est negligeable. Le transfert de rnatikre ; t eti mesure pour differents solutes: acide n-butyrique, acide benzoi'que et phenol. Les hauteurs globales de I'uniti de transfen (phase continue) sont comprises entre 10 et 20 cm pour les acides organiques mais elles sont plus elevi-es pour le transfert du phenol a partir de solutions trks diluees. Les caracteristiques de la colonne h plateaux vibrants sont coniparees a celles d'autres types d'extracteurs et des suggestions sont apportees pour de nouveaux dkveloppements.Keywords: axial mixing, liquid-liquid extraction, vibrating plate column. ow frequency reciprocating plate and pulsed plate L extraction columns are well known. Less attention has been paid to the use of high frequencies (10-200 Hz) and low amplitudes (< 1 mm) as a means of plate agitation, despite the potential advantage that the electrical service frequency (60 Hz) can be used to power simple and reliable electromagnetic drives.The background in these areas has been reviewed by Baird et al. (1989) who also described preliminary tests of both liquid-liquid and gas-liquid contact in single cells using vibrating perforated plates. Rama Rao et al. (1991) have described the hydrodynamic behaviour of a 5 cm diameter countercurrent extractor agitated by a stack of perforated Teflon plates equipped with segmental downcomers. By the use of small perforations (1 mm or less) it was possible to obtain drops with a Sauter mean diameter considerably less than 1 mm with only moderate levels of agitation (amplitudefrequency product...