Considering　that　2%-8%　F　contained　in　lepidolite,　an　improved　sulfuric　acid　method　with　introducing　fluorine　additives　has　been　proposed　to　enhance　its　lithium　extraction.　Herein,　an　acid　mixture　of　hydrofluoric　acid　and　sulfuric　acid　(HF/H2SO4)　was　employed　to　theoretically　investigate　the　dissolution　mechanism　due　to　that　the　HF　molecules　are　the　real　reactive　components　of　the　fluorine　additives.　A　stepwise　heat　treatment　for　fluorine　removal　has　been　proposed　based　on　the　different　boiling　point　of　HF-H2O　and　H2SO4-H2O　subsystems　of　the　acid　leaching　solution.　Effects　of　heating　temperature　(200　°C-350　°C),　heating　time　(6　h,　12　h),　initial　ratio　of　ore/H2SO4　(1:1.5–1:3.5　g/mL)　and　different　heating　style　(one　step　or　stepwise)　on　fluorine　removal　and　lithium　recovery　have　been　carried　out.　Based　on　the　elemental　and　composition　analysis　of　liquid　and　corresponding　solid　phase,　an　optimal　condition　for　fluorine　removal　was　established:　about　0.68%　fluorine　remained　in　leaching　slurry　after　the　stepwise　heat　treatment　at　120　°C　for　3　h　and　200　°C　for　6　h　with　initial　ratio　ore/HF/H2SO4　of　1:2:2　g/mL.　The　retention　of　Li　was　remained　at　a　relatively　high　level　as　94.26%.　The　resulted　siliceous　residues　and　undissolved　quartz　indicates　that　selective　leaching　of　Li　was　achieved　during　this　stepwise　heat　treatment,　which　is　beneficial　for　subsequent　purification　and　lithium　production.　©　2020　Elsevier　B.V.