Purification of metallurgical grade silicon (MG- Si) by a combination of solvent refining and physical separation has been studied. MG-Si was alloyed with iron and solidified under different cooling rates to grow pure Si dendrites from the alloy. The Si dendrites and FeSi2 that were formed after solidification were then separated by a gravity-based method. The separation method relies on significantly different densities of Si and FeSi2, and uses a heavy liquid with specific gravity between the two phases to float the former on the surface of a heavy liquid, while the latter sinks to the bottom. The effect of particle size and cooling rate on the Si yield and separation efficiency of the Si phase was investigated. The floated Si particles were further purified by removing the physically adherent Fe-Si phase, using an acid leaching method. Analysis of the produced silicon indicates that several impurity elements including P and B can be efficiently removed using this simple and low-cost technique.

Purification of metallurgical grade silicon (MG- Si) by a combination of solvent refining and physical separation has been studied. MG-Si was alloyed with iron and solidified under different cooling rates to grow pure Si dendrites from the alloy. The Si dendrites and FeSi2 that were formed after solidification were then separated by a gravity-based method. The separation method relies on significantly different densities of Si and FeSi2, and uses a heavy liquid with specific gravity between the two phases to float the former on the surface of a heavy liquid, while the latter sinks to the bottom. The effect of particle size and cooling rate on the Si yield and separation efficiency of the Si phase was investigated. The floated Si particles were further purified by removing the physically adherent Fe-Si phase, using an acid leaching method. Analysis of the produced silicon indicates that several impurity elements including P and B can be efficiently removed using this simple and low-cost technique.

Les concentrateurs Falcon permettent de séparer des particules en fonction de leur densité. Leur capacité à traiter des débits de suspension importants rend leur utilisation courante dans les procédés miniers. Dans les gammes de tailles ultrafines (entre 1 et 100 μm), leur coupure devient à la fois granulométrique et densimétrique. Ce travail a porté sur la compréhension de leur physique et de ses limites. Une analyse de leurs mécanismes de séparation a abouti à une loi d’échelle analytique, validée expérimentalement. Des investigations plus complètes appliquées aux suspensions ultrafines ont été réalisées numériquement. Finalement un critère physique liant la gamme de taille à séparer aux densités des différentes fractions a été explicité et appliqué à la valorisation de sédiments fins. / Enhanced gravity separators are widely used in minerals beneficiation, as their superior gravity field enables them to separate particles within narrow classes of density and size. This study aims to shed light on the Falcon concentrator’s ability to separate particles with size and density ranges lower than usual, 1 to 100 micrometers and 1.2 to 3.0 s.g. respectively. Differential particle settling being identified as the prevailing separation mechanism under such conditions, this study couples a theoretical and numerical approach with targeted experiments to build a predictive Falcon separation model that embeds phenomenological fluid and particle flow analysis. Based on this model, physical limitations were identified and quantified through explicit relations between operating parameters, and particle size and density ranges. Falcon’s efficiency to beneficiate dredged sediments was characterized in this way.

Parent Adaptive Doll Play, a technique in an early stage of development, is designed for use by parents in assisting their young children to cope with the stresses of parental separation/divorce. The effects of technique implementation by parents of three- through six-year-old children were investigated. Data was collected before and after parents received training and implemented the technique over an eight-week period. Parents completed the Child Behavior Rating Scale, Burks' Behavior Rating Scales, the Parenting Stress Index, and the Parental Attitude Scale. Twenty-two parents, reporting marital separation through separation and/or divorce, within 18 months prior to the beginning of the study, and reporting more than 50 percent physical custody of a three- through six-year-old child qualified for participation. Twelve children were experimental subjects and ten were control subjects. To determine differences between groups, a one-way analysis of covariance was performed on each post test variable. Positive differences were calculated in several areas of child behavior by parents of subjects in the experimental group. No significant differences between groups were found in any area of child behavior. The score which most closely approached significance, however, was found in the Burks' Behavior Rating Scale area of poor anger control.