Selective flotation of silicates from phosphates using Tetrabutyl Ammonium Chloride as a green collector

This study introduces Tetrabutyl Ammonium Chloride (TBAC) as a novel selective collector for silicates in the reverse flotation of apatite-quartz model sample. Zeta potential measurements, contact angle analysis, FTIR, and X-ray fluorescence spectroscopy (XPS) were employed to investigate reagent adsorption at mineral-water interfaces. FTIR analysis revealed the appearance of new peaks corresponding to C–H and C–N stretching in TBAC-treated quartz, but not in apatite, indicating TBAC's preferential adsorption on quartz surfaces. XPS analysis further supported FTIR results; a distinct N 1s peak at 401.5 eV was observed on TBAC-treated quartz, while no such peak appeared on apatite, confirming the absence of significant interaction. Zeta potential measurements showed a larger shift in surface charge for quartz than for apatite after TBAC treatment, particularly at higher pH levels, with a notable shift of +16.28 mV at pH 11 for quartz, compared to only +0.4 mV for apatite. Contact angle measurements also demonstrated that TBAC significantly increased quartz hydrophobicity—reaching values above 115°—while apatite showed minimal change. Flotation tests were conducted to evaluate the performance of TBAC as collector for apatite and quartz. In single mineral flotation, the highest quartz recovery (97%) was achieved at pH 11 with a TBAC dosage of 150 g/ton while the apatite recovery was reduced to 31.6%. The binary-mineral system showed a higher recovery of apatite with a commercial quartz collector at 52.4%, compared to just 25.3% when TBAC was used. Comparative tests with a conventional DA collector revealed that apatite recovery was significantly higher with DA (52.4%) than with TBAC (25.3%), emphasizing TBAC's limited interaction with phosphate minerals and its potential utility for silicate removal in reverse flotation processes. • Using the Tetrabutyl Ammonium Chloride “TBAC” as a selective green collector of silicate in quartz-apatite flotation system for the first time. • Extensive adsorption studies were conducted on the behavior of TBAC on quartz and apatite surfaces. • High separation efficiency was observed when TBAC was used at 150 g/ton and pH 11, the highest quartz recovery reached 97%. • Comparison between TBAC and a commercial quartz collector was studied at the optimum flotation conditions.