Application of a fungal cellulase as a green depressant of hematite in the reverse anionic flotation of a high-phosphorus iron ore

•Cellulase was used as a depressant in flotation separation of apatite from hematite.•Hematite was totally depressed by cellulase at pH10, using oleate as a collector.•Excellent separation was achieved during flotation of mixed pure minerals.•Phosphorus content was reduced in the flotation of a high-phosphorus iron ore.