Flotation　is　a　potential　method　for　extracting　residual　copper　sulfide　(CuS)　from　the　acid-leaching　residue　of　copper　smelting　dust;　however,　the　inhibitory　impact　of　Bi(III)　in　the　flotation　pulp　significantly　hampers　its　practical　application.　In　this　study,　we　systematically　investigated　the　inhibition　mechanism　of　Bi(III)　on　CuS　flotation　and　propose　a　method　to　prevent　inhibition.　Microflotation　test　results　show　that　a　pulp　environment　with　pH　3　and　a　Bi(III)　concentration　greater　than　1　×　10–2　mol/L　significantly　depresses　the　floatability　of　CuS.　Scanning　electron　microscopy　and　energy-dispersive　spectroscopy　results　confirmed　that　Bi(III)　hydrolyzes　on　the　surface　of　CuS　to　form　a　precipitate　cover　layer,　which　adsorbs　onto　the　surface　of　CuS.　This　precipitate　was　confirmed　by　X-ray　photoelectron　spectroscopy　analysis　and　thermodynamic　calculations　to　be　BiOCl.　Fourier　transform　infrared　analysis　revealed　that　BiOCl　reduces　the　recovery　of　CuS　by　hindering　the　adsorption　of　xanthate.　Finally,　the　pre-treatment　of　the　leaching　residue　with　H2SO4　+　NaCl　solution　can　dissolve　BiOCl　precipitates　on　the　surface　of　CuS,　eliminate　the　influence　of　Bi(III),　and　result　in　efficient　flotation　recovery　of　CuS　from　leaching　residue.　©　2024　Elsevier　Ltd