Co-firing　of　low-volatile　carbon-based　solid　fuels　with　bituminous　coal　is　an　encouraging　approach　to　realize　the　large-scale　clean　utilization　of　pyrolyzed　and　gasified　semi-cokes.　However,　the　interactions　on　co-combustion　characteristics　between　bituminous　coal　and　semi-cokes　have　yet　to　be　fully　understood,　while　less　work　has　aimed　at　fuel-nitrogen　migration　mechanisms　without　the　influence　of　thermal-NO　generation.　Here,　an　experimental　investigation　of　bituminous　coal　blended　with　pyrolyzed　semi-coke　and/or　gasified　semi-coke　in　O2/Ar　atmosphere　was　performed　focusing　on　NO　yield,　burnout　performance　and　fuel-nitrogen　migration　mechanisms.　The　characterization　and　reactivity　of　bituminous　coal　and　semi-cokes　were　revealed　by　thermalgravimetric　analyzer,　etc.　The　results　indicate　that　the　promotion　effects　of　bituminous　coal　on　combustion　of　semi-coke　are　enhanced　with　the　enlarged　difference　between　volatile　contents　of　various　samples.　The　char-nitrogen　of　semi-cokes　are　mainly　converted　to　NO　firstly,　and　then　might　be　converted　to　HCN　and　N2　by　pyrolysis　products　HCN,　NH3　and　CHi.　The　method　of　staged　feeding　could　lessen　the　interactions　between　semi-cokes　and　bituminous　coal,　which　could　significantly　inhibit　the　conversion　of　fuel-nitrogen　to　NO　compared　with　the　strategy　of　out-furnace　blending.　The　present　research　can　offer　guidance　for　co-firing　of　low-volatile　semi-cokes　with　bituminous　coal　in　power　stations.　©　2021　Elsevier　Ltd