Study on the flotation separation mechanism of diaspore from kaolinite using mixed NaOL/BHA collector

[Display omitted] •Mixed NaOL/BHA exhibited better collecting ability and selectivity than NaOL.•NaOL and BHA co-adsorpted in diaspore surface.•BHA inhibited the chemisorption of NaOL on kaolinite.•Use of mixtures decreased bubble size and foamability & foam stability. In this paper, oleate sodium (NaOL) and benzohydroxamic acid (BHA) was introduced as a mixed collector for diaspore ores. The flotation behavior and the adsorption mechanism of mixed NaOL/BHA collector to diaspore and kaolinite was investigated by flotation tests, FTIR spectra analysis, zeta potential analysis, surface tension analysis and foam performance tests. The flotation results demonstrated that compared to NaOL, mixed NaOL/BHA collector exhibited superior collecting property and selectivity to diaspore against kaolinite. In detailed, the recovery of kaolinite reduced by 20.01% and the aluminum–silicon ratio (A/S) increased by 9.42 in micro-flotation tests; the total recovery rate was increased from 86.42% to 90.85%, and the A/S was increased from 10.68 to 15.27 in bench-scale flotation of a bauxite ore. The FTIR spectra and zeta potential analysis shows that BHA can promote the adsorption of NaOL on diaspore, and inhibit the adsorption of NaOL on kaolinite. The mixed NaOL/BHA collector not only has a significant effect on mineral selective adsorption, but also affects the surface activity of gas–liquid interface and flotation foam characteristics, thus affecting the flotation separation of these two minerals. The addition of BHA ensures that NaOL has good foaming properties and at the same time makes the foam less sticky, which can reduce the gangue minerals entrained in the foam product and is beneficial to the subsequent treatment of foam products such as filtration and dehydration.