The Sepon Gold Mine in Lao PDR undertook a flotation circuit optimisation program to improve concentrate quality by reducing carbonate (dolomite) reporting to the flotation concentrate while maintaining overall gold recovery. Although the installation of a regrind circuit improved mineral liberation, it also reduced cleaner flotation carrying capacity, resulting in lower cleaner recovery and increased carbonate entrainment. Following optimisation of the existing flotation circuit, additional flotation technologies were evaluated to address the remaining cleaner circuit limitations. Laboratory investigations followed by pilot-scale evaluations of the Eriez Cavitation Tube Column and StackCell technologies were undertaken under plant operating conditions to assess their suitability for improving flotation selectivity. Laboratory and pilot-scale testing demonstrated that the Cavitation Tube Column rejected more than 70 per cent of the calcium contained in the rougher concentrate while maintaining stage gold recoveries of approximately 85–88 per cent. Parallel pilot trials comparing two-stage StackCell and existing two-stage Jameson Cells configurations showed that the StackCell circuit produced approximately twice the concentrate grade at comparable overall gold recovery while operating at lower mass pull and reduced concentrate calcium grade. Based on the pilot outcomes, two Cavitation Tube Columns were installed as Phase 1 of the flotation circuit upgrade. Statistical evaluation of industrial operating data collected during six weeks of column operation (n = 75) and four weeks of offline operation (n = 47) confirmed measurable improvements in metallurgical performance. Phase 1 achieved approximately 15 per cent additional calcium rejection while maintaining overall flotation gold recovery within 1 per cent of baseline performance. Statistical analysis demonstrated a significant increase in final concentrate gold grade (p < 0.001) together with a significant reduction in overall calcium recovery to concentrate (p < 0.001), consistent with the trends observed during laboratory and pilot testing. The Phase 1 results provided the engineering basis for approval of Phase 2 of the flotation circuit upgrade, comprising four StackCell units in the rougher flotation circuit together with an additional Cavitation Tube Column downstream of the regrind circuit. This paper presents the laboratory, pilotscale and industrial operating results supporting the staged flotation circuit upgrade at Sepon and demonstrates the value of integrating laboratory investigations, pilot-scale validation and industrial verification when implementing flotation circuit modifications in complex gold processing operations.