Abstract
In practical celestite flotation, iron contamination is commonly found on celestite surfaces. The effect of ferric ions on celestite flotation was assessed by a combination of ion release experiments, DFT calculation, X-ray photoelectron spectroscopy (XPS) analysis, adsorption isotherm study, and flotation experiments in this work. The ion release experiments showed that the associated limonite released ferric ions to solution. According to DFT calculation and surface complexation theory, we found that ≡SrOH0 and ≡SO4H0 are primary functional groups on celestite surface in aqueous environments. The XPS analysis and adsorption isotherm study revealed that ferric ions mainly adsorbed on celestite surface by complexing with two oxygen atoms of surface ≡SrOH0 groups to form ≡Sr–O–Fe–OH precipitates. Flotation results showed that ferric ions strongly depressed celestite flotation. Combined with the change in surface properties determined by XPS, it can be concluded that the adsorption of ferric ions on celestite surface decreased adsorption sites for the collector, and hence, led to depression on celestite flotation.
Highlights
Strontium has been widely used in industry in the last several decades
Ferric ion release experiments from limonite were conducted to investigate the presence of ferric ions in celestite flotation environment
The celestite flotation was inevitably affected by ferric ions released from associated limonite
Summary
Strontium has been widely used in industry in the last several decades. Celestite (SrSO4 ) is the primary strontium mineral, and it is the main source of strontium metal and various strontium chemicals [1]. Flotation is widely used in the beneficiation of celestite due to the low cost and easy operation [4,5]. The practical mineral flotation pulp is characterized by complicated ion composition, which has significant influence on mineral surface properties and solution chemistry properties, leading to an inevitable effect on flotation results [6]. These phenomena can either promote or inhibit the adsorption of flotation reagents, and influence the flotation process. Ferric ion is considered to be a common unavoidable ion which may exert significant influence on mineral flotation even at low concentrations. Deng et al [11] reported that the adsorption of ferric ions changed the atomic composition and chemical state of smithsonite surface, Minerals 2019, 9, 405; doi:10.3390/min9070405 www.mdpi.com/journal/minerals
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