Experimental Study On Process For Metallic Reduction-Dressing Separation Of Ludwigite

In this paper, a new process for metallic reduction and separation of ludwigite is proposed, which is based on the characteristics of ludwigite, the conditions of coal resources and the present situations of metallic reduction developments in our country. By means of experimental study, metallic reduction of ludwigite process parameters was initially established, such as the reduction time, reduction temperature, coal particle size, and the FC/O (mole ratio), particle size of ludwigite The basic law of ludwigite appropriate reduction and the basic law of iron separated from boron, magnesium, and silicon are analyzed. Combined with experimental study, reduction thermodynamics and element migration law of ludwigite are researched through thermodynamics calculation software FactSage. The exploratory experiments conclusions of ludwigite metallic reduction-dressing separation are given as follows:(1) The ludwigite is made up of Fe3O4, MgFe2O4, Mg2FeBO5, Mg3Si2O5(OH)4, MgBO2(OH), MgO, etc. Because of complicated dissemination in minerals, agglutination among iron, silicon and boron minerals, tiny particles, it is difficult to realize Fe-B separation by conventional methods.(2) The high efficient Fe-B separation in ludwigite can be achieved by this new technology of metallic reduction-dressing separation. When the carbon ratio is 1.4, the particle size of coal is between 0.5 and 1.5 mm, reduction temperature is 1250℃, reduction time is controlled of 60 min, the particle size of ludwigite is between 0.5 and 2.0 mm, and the magnetic field strength is selected at 50 mT, the new process indexes are given as follows:the grade of dressing product is 87.78%, the metallization is 93.52%, the yield of iron also reaches 88.02%, besides the grade and yield of boron oxide is 15.88% and 88.86% separately in tailings. Besides the grade and yield of magnesium oxide is 43.75% and 94.60% separately in tailings. Besides the grade and yield of silicon dioxide is 24.51% and 98.66% separately in tailings.(3) The optimized parameters are given, such as the carbon ratio is 1.4, the temperature is 1250℃, the time is no less than 60 min, and the particle size of coal is between 0.5 and 1.5 mm, the particle size of ludwigite is between 0.5 and 1.5 mm.(4) The product of dressing is the iron powder with high metallization, through the further disposition, which can be used in steel production. The tailings of dressing are high grade sources containing boron, which can be used as superior raw material in boron industry.(5) Through FactSage thermodynamic calculation and XRD experiment and research, the element migration patterns in the isothermal reduction process of is analyzed, as follows:Fe3O4â†'FeOâ†'FeMg2B2O4(OH)2â†'Mg2B2O5â†'Mg3B2O6Mg3Si2O5(OH)4â†' (Mg3Si2O7)â†'Mg2SiO4â†' MgSiO3Fe3Si2O5(OH)4â†' (Fe3Si2O7)â†'Fe2SiO4â†' Fe(6) With the increase of temperature or the rise of time, in the reaction system iron quality gradually increases, Fe2SiO4 quality gradually reduces. Mg2SiO4 content in the system falls. MgSiO3 content is in the rising trend.