To achieve the efficient flotation separation of cassiterite from fluorite, an eco-friendly depressant, the disodium salt of adenosine 5′-triphosphate (Na 2 ATP), was employed for the selective depression of fluorite. The performance of Na 2 ATP as a depressant in the flotation of cassiterite and fluorite was evaluated by micro-flotation experiments in a sodium oleate (NaOL) system. The flotation tests revealed that Na 2 ATP significantly depressed the flotation of fluorite compared to that of cassiterite, and excellent separation was achieved using 1.0 mM Na 2 ATP and 0.14 mM NaOL at pH 8.02. Moreover, the mechanism of the selective depression Na 2 ATP on the two minerals was revealed by surface analyses, revealing that chemisorption between the phosphate group of Na 2 ATP and the calcium ions on the fluorite surface was responsible for the selective adsorption of Na 2 ATP on fluorite, and the significant pre-adsorption of Na 2 ATP onto the fluorite surface impeded the further adsorption of NaOL. However, because Na 2 ATP was adsorbed on cassiterite by physisorption, which is relatively weak, the strong chemisorption of NaOL on cassiterite occurred regardless of pre-treatment with Na 2 ATP. Furthermore, density functional theory calculations revealed that the adsorption mode of Na 2 ATP to be “horizontal” and to occur at multiple calcium-ion sites on the fluorite surface. In summary, Na 2 ATP is a suitable high-efficiency depressant for the separation of cassiterite from fluorite by direct flotation.
Adenosine 5′-triphosphate disodium salt (Na 2 ATP) was used as the efficient depressant for the separation of cassiterite from calcite . The effect of Na 2 ATP on the flotation of cassiterite and calcite was evaluated by the micro-flotation experiments, and the results showed that an excellent separation performance was achieved at the reagents regime of 1.0 mM Na 2 ATP and 0.14 mM NaOL when pulp pH was 9.11. Moreover, the adsorption and depression mechanism of Na 2 ATP on calcite was investigated via a series of surface analyses. The contact angle analysis and zeta potential measurements showed that Na 2 ATP was strongly adsorbed onto the calcite surface rather than cassiterite surface, and that could still significantly enhance the hydrophilicity of the calcite after conditioned with NaOL. The FTIR analysis and XPS analysis results indicated that the interaction between Na 2 ATP and calcite was the chemical binding, and the calcium atom on the calcite surface and the phosphate group of Na 2 ATP was the major reaction unit in this processing. Furthermore, the pre-adsorption of Na 2 ATP on calcite surface would impede the interaction between NaOL and calcite, but the adsorption of NaOL on cassiterite surface could not be affected by the weak physical adsorption of Na 2 ATP. Therefore, Na 2 ATP could be utilized as a potential depressant for removing calcite from cassiterite.
Bin Yang,Haoran Sun,Donghui Wang,Wanzhong Yin,Shaohang Cao,Yulian Wang,Zhanglei Zhu,Kai Jiang,Jin Yao
Up to now, there is still a great challenge to efficiently separate magnesite from calcium-bearing carbonate minerals, especially dolomite, via froth flotation owing to their similar physicochemical properties. In this investigation, a novel depressant adenosine 5′-triphosphate disodium salt (Na 2 ATP) was introduced into the flotation process using the collector sodium oleate (NaOl), which was proved to be effective for the separation of dolomite and magnesite. The flotation results demonstrate that Na 2 ATP exhibits a more intense depression on the flotation of dolomite than that of magnesite and can separate effectively magnesite from dolomite, which depends on much less NaOl adsorption onto dolomite in the presence of Na 2 ATP. Zeta-potential detection and adsorption amount tests illustrate that the pre-addition of Na 2 ATP strongly interferes with the interaction between NaOl and dolomite so that a more significant reduction in adsorption of NaOl on the surface of dolomite in comparison with magnesite. Moreover, infrared spectral (IR) and X-ray photoelectron spectroscopy (XPS) measurements further confirm that the depressant Na 2 ATP is adsorbed more strongly onto dolomite than magnesite. And the selective adsorption of Na 2 ATP onto dolomite rather than magnesite was mainly due to the strong bonding of its phosphate groups and the calcium sites only exposed to the dolomite surface, resulting in selectively depressing the flotation of dolomite.
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