Improved Flotation Separation of Apatite from Calcite with Benzohydroxamic Acid Collector

ABSTRACT

Apatite (Ca₁₀(PO₄)₆F₂) is the most important phosphate mineral, and flotation is the main beneficiation method to separate apatite from its major gangue mineral calcite (CaCO₃). Till date, fatty acids and their salts have been widely used as collectors in the apatite/calcite flotation separation due to their low cost and strong collecting ability, but their selectivity is limited. Therefore, screening or designing a selective collector becomes the key to the efficient separation. In this work, an attempt was made to utilize benzohydroxamic acid (BHA) as the collector for the selective separation of apatite from calcite without any depressant. The single and mixed binary mineral flotation experimental results prove the excellent selectivity of BHA in the apatite/calcite flotation separation. Zeta potential measurement results indicate a greater affinity of BHA on the apatite surface than calcite, which is also confirmed by the higher adsorption energy of BHA on the apatite surface based on the first-principle density functional theory calculations. The X-ray photoelectron spectroscopy analysis shows that the selective chemisorption of BHA on apatite over calcite is due to the stronger reactivity and the higher density of Ca²⁺ ion on the apatite surface than calcite. This work shows that surfactants of hydroxamic acid type can be an ideal collector for phosphate mineral flotation.

KEYWORDS:

• Apatite
• calcite
• flotation
• separation
• benzohydroxamic acid (BHA)

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51774328 and 51404300]; National 111 Project [B14034]; Innovation Program for Postgraduate Students of Central South University [2018zzts037]; Innovation-Driven Program of Central South University of China [2017CX007]; Natural Science Foundation of Hunan Province of China [2018JJ2520]; Young Elite Scientists Sponsorship Program by CAST [2017QNRC001].