Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11000733 | Minerals Engineering | 2018 | 11 Pages |
Abstract
Selective depression of calcite in a monazite-calcite flotation system was systematically studied using micro-flotation and electrokinetic tests as well as X-ray photoelectron spectroscopy (XPS) characterization and solution chemistry calculations. Monazite was found to be depressed by both sodium silicate and sodium hexametaphosphate when calcium ions appeared in solution. It was hypothesized that co-adsorption of calcium species (CaHCO3+ and CaCO3(aq)) and Si(OH)4 as well as SiO(OH)3- via hydrogen bonding formed a compact layer over the monazite surface, thereby reducing octanohydroxamic acid adsorption by steric hindrance. The use of citric acid or EDTA formed soluble chelates (e.g. CaCitâ and CaEdta2â) with the calcium ions which negated the flotation suppression effect. An XPS study indicated that both EDTA and citric acid chemically adsorbed on the monazite surface, while the adsorption on the calcite surface was achieved mainly through hydrogen bonding. EDTA was more effective than citric acid due to two reasons: (i) citric acid itself presented stronger depression effects and (ii) citric acid has weaker chelating properties for calcium. Using 2.5â¯Ãâ¯10â4â¯M octanohydroxamic acid, 0.05â¯g/L sodium silicate and 6â¯Ãâ¯10â5â¯M EDTA, monazite recovery of more than 90% was achieved while recovering only 20% of the calcite.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Engineering (General)
Authors
Wencai Zhang, Rick Q. Honaker,