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The selective depression effect of sodium hexametaphosphate on the separation of chlorite and specularite

Zhao Fugang, Yu Xiankun, Gao Xiangpeng, Li Mingyang, Chen Xiangxiang

Physicochemical Problems of Mineral Processing

2023

Vol. 59, iss. 2

art. no. 166495

Flotation is the most known beneficiation method for the separation of complex and refractory iron ores. As a typical iron-containing silicates, it is difficult to separate chlorite from specularite, because of the similar surface physicochemical properties. In this study, the selective depression effect of sodium hexametaphosphate (SHMP) was conducted via the cationic micro-flotation. The surface adsorption mechanism between SHMP and the two mineral surface was explored through surface adsorption amount tests, Zeta-potential measurements, Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The micro-flotation results indicated that SHMP could selectively depress around 90% of chlorite, while its effect on the floatability of specularite was negligible (<20% depressing). The surface adsorption amount tests, Zeta-potential measurements analysis demonstrated that SHMP selectively adsorb on chlorite surface while on the surface of specularite is feeble. The further surface adsorption analysis via FT-IR and XPS proved that SHMP selective adsorption occurred on the chlorite surface mainly by chemisorption mainly through the chelation reaction between O in the phosphate groups of SHMP molecular and metal ions on surface of chlorite.

Structure-activity of chelating depressants for chalcopyrite/pyrite separation: DFT study and flotation experiment

Li Mingyang, Lian De, Zhao Fugang, Tong Xiong, Wu Chaoyang, Gao Xiangpeng

Physicochemical Problems of Mineral Processing

2021

Vol. 57, iss. 6

102--112

Three types of chelating depressants were studied for chalcopyrite/pyrite separation, including S-S, S-O, and O-O types, via density functional theory calculations and microflotation. The calculation results indicate that the depressant’s chelating atoms have large coefficient and great activity according to the molecular frontier orbital (HOMO and LUMO) and the orbital coefficients. For S-S type of depressant, S atom in both keto or enol forms won’t affect their HOMO and LUMO patterns and the orbital contributions. For S-O type, the presence of N atom in the ring structure of a molecular will increase the reactivity of O-Cu while weak S-Cu. For O-O type, the electron supply capacity of benzene ring is higher than strain chain, and atom N in strain chain increased their electron supply capacity. The microflotation results basically confirmed the prediction based on the calculation. The simulation results demonstrate that the interaction of a depressant with metals and minerals are affected obviously by the spatial structure and electronic structure of an atom in its molecular.