Beneficiation of Low-Grade and High-Phosphorus Iron Ore of Bajrawia, Sudan by Reverse Anionic Flotation: Potential of Microwave Treatment

Deposits of low grade and high-phosphorus iron ores are spreading globally, however, the usage of this kind of deposits in the manufacturing of steel bounded because of the high-phosphorus content as well as depression of iron in which affect the quality of the produced steel. The Bajrawia iron ore deposit is one of the largest in Sudan but it only contains (35.5% Fe) and undesirable amount of phosphorus (0.37% P). This paper investigated the utilization of reverse anionic flotation (RAF) for the upgrading of iron and dephosphorization. Additionally, the effect of microwave pre-treatment on forth flotation performance on a laboratory scale. Microwave pre-treatment was applied on optimized reverse anionic flotation parameters in an account of iron grade (47.31% Fe), iron recovery (86.43%) and phosphorus content (0.167% P). The findings into the microwave pre-treatment are quite promising. This investigation has revealed that microwave heating improves the flotation response of iron grade to (51.94%) and phosphorus content decreases into (0.127% P) due to increasing the liberation.

Research on Reaction Mechanism of Vacuum Carbon Thermal Reduction and Dephosphorization in High Phosphate Iron Ore

According to the mineral composition characteristics of high-phosphorus iron ore, the reaction mechanism of fluorapatite was investigated using pure substance and gangue under vacuum carbon thermal reduction (VCTR) conditions. The effects of reduction temperature, basicity, and C/O ratio on the metallization ratio, dephosphorization ratio, and phosphorus content of pellets were studied. The reaction process of fluorapatite in high-phosphorus iron ore was investigated. The results showed that when the metallization ratio of pellets reached maximum (95%), the dephosphorization ratio was only 5.6%, thus indicating adverse result. The reduction processes of high-phosphorus iron ore under vacuum and nitrogen environment were, respectively, compared under the optimal condition. It was found that the metallization ratio of pellets in the vacuum condition was higher than that under the nitrogen condition, while the dephosphorization ratio showed an opposite result. This indicated that in the process of vacuum reduction, fluorapatite not only reacted with carbon to form gaseous phosphide, but also with iron to form compounds containing the Fe–P bond. Therefore, a new mechanism of reduction of fluorapatite was proposed as follows: 2Ca5(PO4)3F + 12Fe + 9SiO2 + 15C = 9CaSiO3 + 6Fe2P + 15CO + CaF2.