The theoretical study on the efficiencies of 2-[tris(hyroxycarbamoyl)methyl] carboxylic acids as chelating agents in flotation separation of diaspore and aluminosilicates

The performance of 2-[tris(hyroxycarbamoyl)methyl] carboxylic acids on flotation separation of diaspore over kaolinite and illite was investigated by using flotation tests, and their collecting performance was clarified by using density functional theory (DFT) calculation and molecular dynamics (MD) simulation. The flotation results of single minerals indicate that by using THDA, THCA or THTA as collector under neutral condition, diaspore presents good flotability while kaolinite and illite exhibit poor flotabilities. Among the three collectors, THCA displays the greatest difference in the flotability between diaspore and aluminosilicate. The flotation results of the artificially mixed minerals show that under the condition of pH 7 and 2 × 10−4 mol/L THCA, the A/S value in the concentrate is greatly increased and the separation of diaspore over aluminosilicates is feasible by using THCA as collector. DFT calculations show that large negative charges are located at the O and N atoms in the polar group of these collectors and the O atoms have more negative charges than N atoms. By comparison THCA has the highest HOMO energy, resulting in the highest collecting efficiency. The adsorption of collector on mineral surface by MD method indicates that the combination processes of collectors with mineral crystal are exothermic, and THCA has the greatest difference in binding energy between diaspore and aluminosilicate. A good correlation was found between the theoretical calculations and the experimental results. As a whole, THCA is a better collector to float and separate diaspore over aluminosilicates.

► Designing and synthesizing tris(hyroxycarbamoyl)methyl carboxylic acid as collector.
► Collector selectively floating diaspore over silicates.
► Easier chelation and higher binding energy on diaspore than on silicates causing collector selective adsorption.