The DFT study of cyclohexyl hydroxamic acid as a collector in scheelite flotation

In this paper, cyclohexyl hydroxamic acid (CHA) was investigated as a new collector for scheelite flotation by the Density Functional Theory (DFT) calculation, mineral flotation tests, adsorption measurement and zeta potential determination. The DFT computation results indicated that the dianion of CHA or benzoylhydroxamic acid (BHA) exhibited stronger chemical reactivity than their anions and neutral molecules, and that the replacement of phenyl group by cyclohexyl group in BHA molecule significantly impacted the electron donating ability of hydroxamate collectors. In alkaline aqueous solutions, the two oxygen atoms in the dianions of CHA or BHA charged more negative charges than other atoms, and hence became their reactive center. The dianion of CHA exhibited higher atomic charge value, HOMO (Highest Occupied Molecular Orbital) energy, bigger dipole moment and binding energy with Ca²⁺, thus it had stronger collecting ability for scheelite than that of BHA. In addition, the results of flotation tests, adsorption measurement and zeta potential determination validated that the collecting capability of CHA was stronger than that of BHA, which achieved excellent agreement with computational analysis.