Selective Flotation of Scheelite from Calcite Using a Novel Reagent Scheme

ABSTRACT

Scheelite and calcite are usually intergrown calcium minerals that are separated via froth flotation. However, their selective separation remains difficult because of their similar surface properties. 2-phosphonobutane −1, 2, 4-tricarboxylic acid (PBTCA or H₅L) is widely used in water treatment due to its low phosphorus content and efficient anti-scaling performance. With its excellent calcium-chelating ability, PBTCA was used as a novel depressant to selectively separate scheelite from calcite in this study. The flotation results of single mineral, binary mixed minerals, and real ore showed that PBTCA could selectively depress calcite at pH 9.0 using sodium oleate as collector. The results of zeta potential measurements, solution chemistry calculation, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculation indicated that the dominant form of PBTCA was L^5-. This anion had a stronger adsorption on negatively charged calcite surfaces through electrostatic interaction. Higher Ca density and stronger Ca activity on calcite promote the adsorption of L^5-. Moreover, the active O atoms in L^5- could better match with two Ca sites on calcite in the interatom distance. Thus, PBTCA provides a new option for calcite depressants and has great industrial application potential.

KEYWORDS:

• scheelite
• calcite
• flotation
• depressant
• PBTCA

Disclosure statement

No potential conflict of interest was reported by the author(s).

PBTCA used as novel depressant to separate scheelite from calcite for the first time.

The dominant form of PBTCA was L^5- and could selectively depress calcite at pH 9.0.

Higher Ca density and stronger Ca activity on calcite could promote L^5- adsorption.

Active O atoms in L^5- match better with Ca sites on calcite in interatomic distance.

The manuscript submitted has been approved by all the authors listed in the paper. It should be emphasized that the work described is original research and no conflict of interest exists in our manuscript. Moreover, the manuscript has not been published previously and is not under consideration for publication elsewhere in whole or in part; National Natural Science Foundation of China [51774328]

Additional information

Funding

Project (51774328 and 51404300) supported by the National Natural Science Foundation of China; Project (2018RS3011) supported by the Young Elite Scientists Sponsorship Program, China; Project (2018JJ2520) supported by the Natural Science Foundation of Hunan Province of China; Project (B14034) supported by the National 111 Project, China; Project (2020JJ2044) supported by the Science Fund for Distinguished Young Scholars of Hunan Province, China; Project (2019zzts312) supported by the Fundamental Research Funds for the Central Universities of Central South University, China.