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Characterization of diglycolamide resin using XRF, SEM, XPS, FTIR.

The recovery was investigated of rare earth elements from a monazite concentrate containing 14.36 wt% Ce, 8.65 wt% La, 16.25wt% Fe and 7.24 wt% P. Dissolution experiments were conducted using tartaric, citric, oxalic and maleic acids. The effects of pH, residence time and the use of tailings mine site water were also studied. Oxalic acid exhibited the highest dissolution potential and was selected for further study. The results showed that the effectiveness of each acid correlated fairly well with their ability to bind rare earths, but citric acid exhibited greater complex stability with rare earths than oxalic acid indicating that reprecipitation of the oxalate is important for increased mineral dissolution. The system exhibited surprising selectivity for the dissolution of monazite over the iron phase, as oxalic acid has a greater binding strength with iron than with rare earths. This may be due to other interactions with the phosphate, the different stability of the specific phases, a kinetic limitation on iron dissolution or preferential adsorption to the monazite surface. The conversion of monazite to rare earth oxalate appeared to exhibit a rate limitation with time possibly due to the precipitating material forming a passive layer on the surface of the monazite or consumption of the oxalate by dissolving ions. A rare earth hydroxide could be produced from the leach residue, allowing the process to be applied to conventional solvent extraction. Tailings water used to investigate the effect of dissolved solids on the process showed a marked decrease in phosphorus release, suggesting a significant decrease in monazite conversion., The recovery was investigated of rare earth elements from a monazite concentrate containing 14.36 wt% Ce, 8.65 wt% La, 16.25wt% Fe and 7.24 wt% P. Dissolution experiments were conducted using tartaric, citric, oxalic and maleic acids. The effects of pH, residence time and the use of tailings mine site water were also studied. Oxalic acid exhibited the highest dissolution potential and was selected for further study. The results showed that the effectiveness of each acid correlated fairly well with their ability to bind rare earths, but citric acid exhibited greater complex stability with rare earths than oxalic acid indicating that reprecipitation of the oxalate is important for increased mineral dissolution. The system exhibited surprising selectivity for the dissolution of monazite over the iron phase, as oxalic acid has a greater binding strength with iron than with rare earths. This may be due to other interactions with the phosphate, the different stability of the specific phases, a kinetic limitation on iron dissolution or preferential adsorption to the monazite surface. The conversion of monazite to rare earth oxalate appeared to exhibit a rate limitation with time possibly due to the precipitating material forming a passive layer on the surface of the monazite or consumption of the oxalate by dissolving ions. A rare earth hydroxide could be produced from the leach residue, allowing the process to be applied to conventional solvent extraction. Tailings water used to investigate the effect of dissolved solids on the process showed a marked decrease in phosphorus release, suggesting a significant decrease in monazite conversion.

Batch-sorption tests were carried out on the recovery of gold and platinum from NaCl solution by commercial grade magnetite powder, looking at the effect pH, contact time, and precious metal and NaCl concentration had on recovery. Au and Pt had similar pH dependent recovery curves, with peaks at pH 6-7. At this pH range, a maximum of 4.4 micro mol Au/g Fe3O4and 3.0 micro mol Pt/g Fe3O4 were recovered after 24 h at an initial metal concentration of 0.05 mol/m3. Metal recovery increased with increasing initial precious metals concentration, and decreased with high NaCl concentration. SEM images showed that the gold had agglomerated and was deposited on the magnetite surface., Batch-sorption tests were carried out on the recovery of gold and platinum from NaCl solution by commercial grade magnetite powder, looking at the effect pH, contact time, and precious metal and NaCl concentration had on recovery. Au and Pt had similar pH dependent recovery curves, with peaks at pH 6-7. At this pH range, a maximum of 4.4 micro mol Au/g Fe3O4and 3.0 micro mol Pt/g Fe3O4 were recovered after 24 h at an initial metal concentration of 0.05 mol/m3. Metal recovery increased with increasing initial precious metals concentration, and decreased with high NaCl concentration. SEM images showed that the gold had agglomerated and was deposited on the magnetite surface.

Leaching tests using chloride media and ferric ions as oxidant were performed to investigate the relationship between the leaching rate of Cu from chalcopyrite and the oxidation-reduction potential. A zone of high leaching rates was found where Cu and Fe concentrations increased sharply; leaching reached a maximum at low oxidation-reduction potentials where ferrous ions were more concentrated than ferric ions., Leaching tests using chloride media and ferric ions as oxidant were performed to investigate the relationship between the leaching rate of Cu from chalcopyrite and the oxidation-reduction potential. A zone of high leaching rates was found where Cu and Fe concentrations increased sharply; leaching reached a maximum at low oxidation-reduction potentials where ferrous ions were more concentrated than ferric ions.

The recovery of platinum group metals (PGMs) from chloride solutions using magnetite was investigated. The adsorption of platinum, palladium, and rhodium in chloride medium onto synthetic magnetite powders were studied at different pH conditions, contact time, sodium chloride concentrations, and initial Pt, Rh, and Pd concentrations. Platinum and palladium uptake by magnetite was at a maximum at pH 6-7, and pH 3-4 for rhodium after 24 h with 0.1 mol/dm3 sodium chloride at an initial PGM concentration of 0.05 mol/m3. A sorption mechanism for PGMs was discussed based on the results. Results indicate that Fe3O4 can uptake PGMs and can be used as a potential selective sorbent to recover the metals from chloride solutions or chloride leach liquors., The recovery of platinum group metals (PGMs) from chloride solutions using magnetite was investigated. The adsorption of platinum, palladium, and rhodium in chloride medium onto synthetic magnetite powders were studied at different pH conditions, contact time, sodium chloride concentrations, and initial Pt, Rh, and Pd concentrations. Platinum and palladium uptake by magnetite was at a maximum at pH 6-7, and pH 3-4 for rhodium after 24 h with 0.1 mol/dm3 sodium chloride at an initial PGM concentration of 0.05 mol/m3. A sorption mechanism for PGMs was discussed based on the results. Results indicate that Fe3O4 can uptake PGMs and can be used as a potential selective sorbent to recover the metals from chloride solutions or chloride leach liquors.