Iron Increase And Phosphorus Removal Technology Of Oolitic Hematite By Floatation And Microwave Roasting

Oolitic hematite is generally acknowledged to be as one of the most complex iron ore for dressing.Due to its fine grain size,complex structure and high phosphorus content,it is difficult to make it meet the smelting requirement using many mineral processing methods.In this paper,the technology of dephosphorization by“flocculation desliming-reverse flotation”and iron removal by"microwave reduction roasting-low-intensity magnetic separation"are used to solve the problem of utilization of oolitic hematite,providing a new way to realize its resource development.By means of XRD,SEM,EDX,chemical detection and microscopic analysis,techno-mineralogical properties of oolitic hematite are firstly analyzed,based on this,the dephosphorization process of“flocculation desliming-reverse flotation”of oolitic hematite is researched.Then the influences of the roasting temperature,pulverized coal proportioning,roasting time on magnetic susceptibility of roasting iron concentrate are studied to determine the best microwave reduction roasting process.Finally,the effects of magnetic field intensity and grinding particle size on the low intensity magnetic separation index of roasting ores are investigated,and the optimum technologic condition of“microwave reduction roasting-low intensity magnetic separation”of iron concentrate is determined.The results show that the best desliming condition for oolitic hematite are the grinding fineness of-0.045 mm?85.5%?,the NaOH dosage of 800 g/t,the sodium silicate dosage of 500 g/t and the starch dosage of300+100 g/t,corresponding iron concentrate grade of 41.55%,recovery of 91.92%.The optimal conditions for reverse flotation of desilted iron ore are as follows:the dosage of activator CaCl₂of 300 g/t,the dosage of collector sodium oleate of 600 g/t,the dosage of pH regulator NaCO₃of 1200 g/t,and the dosage of inhibitor starch of 800 g/t.The optimum condition of microwave reduction roasting for concentrate after flotation is the temperature of 650?,pulverized coal addition of 15%,the roasting time of 10 min and the reduction roasting effect is the best under this condition,the magnetic susceptibility was 2.38.Under the conditions of magnetic separation with the magnetic field intensity of 80 kA/m,grinding fineness of-0.038 mm?41.5%?,the index of the magnetic iron concentrate is best,and by“one roughing and one scavenging”low intensity magnetic separation process,the magnetite concentrate is finally obtained with the iron grade of 62.8%,operating recovery of 82.5%and phosphorus content of 0.27%.