Abstract
Fluorite is a nonrenewable mineral used to produce anhydrous hydrofluoric acid (AHF) and aluminum fluoride. The demand for low-grade fluorite powder (CaF2 < 97%) has fallen sharply owing to the current market conditions. Therefore, a large number of fluorite concentrates have been improved by acid leaching. While this approach can efficiently remove CaCO3 from fluorite concentrate, the SiO2 content, which significantly affects AHF consumption during the production of HF or aluminum fluoride, cannot be completely removed. To solve this problem, in this study, we used reverse flotation before leaching the fluorite concentrates. Subsequently, the feasibility of reverse flotation desilication was determined. The obtained results of the ZP (zeta potential) measurements, solution chemistry analysis, FTIR (Fourier transform infrared spectroscopy) analysis, and micro-flotation tests indicated that employing dodecylamine as the collector and citric acid as the depressor could effectively separate sericite from fluorite. The batch flotation experiment and the pilot test were conducted in Chenzhou (Hunan, China) followed by their operation in Xinyuan Mining Co. Ltd., which produces monolithic fluorite ore on the large scale in Asia. Notably, we found that the contents of both SiO2 and Al2O3 were from 2.82%, 1.17% reduced to 1.28%, 0.74% in the batch flotation experiment. The results of the pilot test showed that the new reverse flotation + leaching technology could dramatically reduce the potential environmental impact and costs, thereby significantly improving the economic benefits by satisfying the requirements of the market.
Highlights
Fluorite (CaF2 ) is a non-renewable mineral and is employed as a flux agent in steelmaking and hydrofluoric acid production [1,2]
The above experiments and analyses demonstrated that the depressant citric acid (CA) and the of the Si-O-Si (Al) or Si (Al)-O groups, respectively [32]
The spectra obtained for sericite with DDA indicated that the –CH3 or –CH2 stretching bands appeared at 2847 and 2919 cm−1
Summary
Fluorite (CaF2 ) is a non-renewable mineral and is employed as a flux agent in steelmaking and hydrofluoric acid production [1,2]. Several studies reported that all commercial fluorite production processes used froth flotation to remove the impurities [3,4,5,6,7] This method was widely employed to remove gangue minerals from fluorite concentrations to further improve the fluorite grade [8,9,10,11]. We decided to use reverse flotation because it can be successful in amine-type, while the valuable minerals are hydrophilic and are enriched in the underflow fraction [13,14,15] This method was alsosilicates reported(quartz to be theor most widely technology cases where the gangue contains mica) andused is floated withfor a collecto the desilicification of various important minerals, i.e., iron ore and magnesite ore [16,17,18].
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