The Research On Process And Mechanism Of Oolitic Hematite's Dephosphorization And Dealuminum

The steel industry is an important basic industry of national economy, with the rapid growth of the national economy, metallurgical technology has a great development,the quality of iron concentrates on higher requirements. While domestic iron ore supply can not meet the needs of the development of steel industry, the dependence on imported iron ore significantly increased,and the international iron ore prices rose rapidly. In order to ensure the stable and sustainable development of steel industry, the exploitation of existing domestic iron ore resources is urgent need, especially the iron ore without development that being limited by technical now, high phosphorus oolitic hematite is an important part of it.Hezhang iron ore is low grade oolitic hematite, the rearch result shows that the properties of the ore are complex, and the contents of phosphorus and aluminium are higher as well as silicon by using chemical component analysis and mineralogy analysis. In view of the above characteristics, in this paper the roasting-magnetic separation-reverse flotation and direct reduction-magnetic separation technology were utilized in order to improve the grade of iron and reduce the contents of phosphorus and aluminum.The results of roasting-magnetic separation-reverse flotation show that the optimum conditions of roasting and magnetic separation are roasting temperature 750℃, the dosage of reductant 9%, roasting time 80min,grind granularity -0.043mm about 93.31%, magnetic field intensity 200kA/m, respectively.Reverse flotation based on regrinding of magnetic separation concentrate was carried out under the condition of pH 11,the dosage of depressor 1750g/t, activator 800g/t, collector R1B 800g/t. Through the above method, the grade of iron concentrate 55.47% with 78.34% recovery were obtained, as well as the content of 0.44% phosphorus and 6.94% aluminum, respectively. Infrared spectrum analysis shows that modified oleic acid and collector R1B mainly composed by hydroxyl and carboxyl. Two kinds of collectors can occur chemical adsorption on the surface of the tailings and in the same conditions chemical adsorption ability of collector R1B is stronger than modified oleic acid.According to the iron ore resources characteristics of Hezhang, the tests of hematite and siderite mixed roasting show that when the mixed proportion of hematite and siderite is 6:4, roasting temperature 750℃, the dosage of reductant 8%, roasting time 80min,grind granularity -0.043mm about 90%, magnetic field intensity 200kA/m, the grade of iron concentrate 58.87% with 87.69% recovery were obtained, as well as the content of 0.29% phosphorus and 5.21% aluminum, respectively.Experimental study shows that the optimum conditions of direct reduction-magnetic separation are reduction temperature 1150℃, the dosage of reductant 50%, reduction basicity 0.6, reduction time 120min, grind granularity -0.043mm about 92.18%, magnetic field intensity 150kA/m, respectively. According to this flow sheet, the grade and recovery of iron concentrate were 72.75% and 92.04% respectively, while the phosphorus grade and aluminum content were 0.43% and 6.14% respectively.