Abstract: Granite pegmatite quartz is a high−quality raw material for producing high−purity quartz, and removing feldspar via flotation is crucial for its efficient utilization. The separation of quartz from feldspar via fluorine−free flotation exhibits low efficiency for high−purity quartz in specific particle−size fractions. Meanwhile, hydrofluoric acid−based flotation causes severe corrosion of flotation equipment. To mitigate these limitations, this study integrates surface pretreatment into the flotation separation protocol for quartz and feldspar within the 0.107−0.187 mm particle−size fraction. Surface activation of the ore sample in this size range was achieved by soaking in a dilute hydrofluoric acid solution, followed by filtration and flotation. Recycling the surface pretreatment waste liquid reduced hydrofluoric acid consumption and mitigated equipment corrosion. Results show: (1) In single−mineral flotation, after surface pretreatment, the recovery rate of feldspar froth product increased from 92.2% to 96.5%, while quartz froth recovery was only 7.93%; (2) In artificial mixed ore flotation, surface pretreatment increased the SiO₂ grade of quartz flotation concentrate from 89.43% to 99.51%. Applying this method to flotation purification of a 0.107−0.187 mm ore sample from a foreign granite pegmatite quartz yielded a quartz concentrate with a SiO₂ grade exceeding 99%. After deep purification, it reached 4N8, meeting the standards for high−end high−purity quartz products; (3) When sodium oleate is applied alone, it presents a weak collecting performance toward feldspar. Nevertheless, combined use of sodium oleate and dodecylamine generates a synergistic effect, which effectively improves the surface hydrophobicity of feldspar. Surface pretreatment selectively etches the feldspar surface, increasing specific surface area and surface negative charge density, making collectors more easily adsorb onto feldspar and raising its contact angle by 17°, further improving hydrophobicity. The enhanced flotation separation method for quartz and feldspar in the 0.107−0.187 mm size fraction proposed here has been successfully applied to flotation purification of granite pegmatite quartz for high−purity quartz production.