Study on magnetic roasting-magnetic separation-inverse flotation for phosphorus reduction of oolitic hematite

The oolitic hematite in the west of Hubei,because of its fine embedded fabric size,and high impurity of silicon dioxide,aluminum oxide,phosphorus etc,it is hard to be used in iron-making.Researches of raising iron grade to reduce phosphorus of oolitic hematite with iron grade of sample 43.76% and content of phosphorus 0.84% were finished in this paper.Studies on factors influencing magnetic roasting on oolitic hematite such as temperature、time of magnetization roasting and ratio of reducing agent were done,the optimum conditions are identified: the hematite are roasted with 11% reducing coal in the temperature of 750 ℃ for 60 minutes.The roasted product is separated by permanent magnetic separator after grinding to 80.54%-0.038 mm.The grade of iron and phosphorus in rough concentrate is 54.10% and 0.80% respectively,iron recovery of 93.19%.After experiment of inverse floatation on concentrate,the grade of iron and phosphorus in rough concentrate is 58.95% and 0.50% respectively with the total Fe recovery 80% based on the optimum conditions: sodium hydroxide dosage of 750 g/t,modified starch dosage of 800 g/t,lime dosage of 500g/t,RA-715 dosage of 750 g/t,G310 dosage of 107.73 g/t,the temperature of flotation pulp is 30 ℃.Then,a cleaning concentration was tested,half of the dosage of lime and collector are added,finally the grade of iron concentrate is 59.87%,the grade of phosphorus is 0.28%,total iron recovery is 71.08%.In consequence of the above results,the technology is feasible and can provide us with effective suggestions in dealing with oolitic hematite.