New separation method of boron and iron from ludwigite based on carbon bearing pellet reduction and melting technology

Abstract

Ludwigite is the most abundant boron resource in China. In order to fully utilize the complex ore and meet the boron and iron consumption of the country, a new process was proposed in this research. Fine ludwigite and pulverized coal were pelletized and then reduced isothermally at high temperatures. The influence of reduction conditions, such as reduction temperature and C/O (mole ratio), on the metallization degree and melting morphology of the samples, were studied in detail. The pellet could not melt well at higher or lower temperature than 1 673 K. The increase in C/O could improve the reduction and melting rate of the pellet. The appropriate temperature and C/O were 1 673 K and 1.2 in the work. When the pellet was reduced at 1 673 K for 12 min, the iron and slag separated in a clean manner. The apparent activation energy of reduction stage was 180.17 kJ/mol. The boron content of nugget and boron oxide (B 2O 3) content of the slag were 0.065% and 20.01%, respectively. In addition, the microstructure, phase transformation and phases composition of the samples were characterized by means of XRD, SEM, EDS and optical microscope. The efficiency of extraction of boron (EEB) of the slag was 86.46% when it was cooled in a slow method. The boron-bearing nugget and boron-rich slag were good raw materials for steelmaking and borax production. © 2012 ISIJ.