Influence of starch on floatability in fluorite and barite in α-BLA system

In this paper, starch was selected as an inhibitor for the flotation separation of fluorite and barite, and a novel anion-modified collector, α-bromo decanoic acid (α-BLA), was employed to enhance ore recovery and achieve selective separation of barite from fluorite. The wettability, Zeta potential, Fourier Transform Infrared Spectrometer，(FTIR), and X-ray Photoelectron Spectroscopy (XPS) results in the α-BLA system were used as a basis to analyze and study the adsorption mechanisms on the mineral surfaces. At pH = 7, with the condition of 40 mg/L α-BLA and 20 mg/L starch, the difference in flotation of fluorite was maximized, and starch exhibited a strong inhibitory effect on barite. Under conditions of sulfuric acid dosage was 75 mg/L, α-BLA dosage was 50 mg/L, and starch dosage was 20 mg/L, a high-quality fluorite concentrate with a Calcium fluoride (CaF2) grade of 97.71 % and a recovery rate of 94.89 % was obtained. With sulfuric acid dosage of 2000 g/t and starch dosage of 400 g/t, a fluorite concentrates with a CaF2 grade of approximately 50.90 % and a recovery rate of around 98 % was achieved, while the barite tailings contained a Barium sulfate (BaSO4) grade of 41.69 % with a recovery rate of 69.85 %. Further increased dosage resulted in only minor variations in CaF2 and BaSO4 grades, but a decrease in recovery rates to 82.57 % and 58.29 % for CaF2 and BaSO4, respectively. This behavior can be attributed to starch's electrostatic adsorption on the fluorite surface, with its hydroxyl groups forming complexes with Calcium ion (Ca2+) on the fluorite surface. After barite dissolution, the presence of Sulfate ion (SO42-) ions in the solution hindered the adsorption of Barium ion (Ba2+) adsorbents on the surface, combined with the inhibitory effect of starch, reducing the number of activated adsorption sites for α-BLA collector, and subsequently lowering its floatability. Based on these experimental results, optimal dosages and pH ranges can be selected for the flotation separation of barite-type fluorite ore. In the process of separating fluorite and barite through flotation, starch can be effectively employed as a barite inhibitor, with α-BLA serving as the collector to achieve efficient separation of fluorite and barite.