Carbothermal Reduction of Boron-bearing Iron Concentrate and Melting Separation of the Reduced Pellet

Abstract

Comprehensive utilization of low grade ludwigite is critical important for the safe supply of boron resource of China. Boron-bearing iron concentrate is the intermediate product of the ore dressing process of crude low grade ludwigite and extracting boron from it has great effect on the total boron yield. Prereduction of the boron-bearing iron concentrate is one of the important steps of the pyrometallurgical boron and iron separation process. The carbothermal reduction study of boron-bearing iron concentrate was carried out in the present work. The reduction rate was improved with the increasing of heating temperature and carbon content. The appropriate temperature and C/O (mole ratio of fixed carbon to reducible oxygen) were 1 200 to 1 300°C and 0.8 to 1.2, respectively. In addition, the microstructure and phase evolution of the pellet during the reduction process were characterized by means of SEM and XRD. The apparent activation energy of the iron oxide reduction in the composite pellet was 114.32 kJ/mol based on the first-order reaction model. The iron and slag separate well when the reduced pellets were heated at 1 550°C. The B2O3 content of the slag and the boron element content of the pig iron were 10.8 wt% and 0.74 wt%, respectively. The main minerals in the slag were olivine, kotoite, periclase and spinel after slow cooling, and the efficiency of extraction of boron (EEB) of the slag was 68.4%. The boron-rich slag and boron-bearing pig iron can be used as the raw materials for boron extraction and steel making.KEY WORDS: carbon composite pellet; direct reduction; boron-bearing iron concentrate; boron-iron separation.

Melting Separation Process of High Chromium Vanadium-bearing Titanomagnetite Metallized Pellet and its Optimization by Multi-Index Synthetic Weighted Scoring Method

“…9) work, both the boron-bearing nugget and boron-rich slag were obtained from ludwigite through carbon bearing pellet reduction-melting technology. No matter BF process and present coal based direct reduction-melting separation process, it should be noted that the reduction by carbon is relatively slow and consumes large amounts of energy.…”

“…[5][6][7] Recently, the technology of direct reduction followed by melting separation applying to dispose special metallurgical resources has attracted increasing attention. [8][9][10][11] Jun et al 8) studied the carbothermal reductionmelting separation process for copper slag. In Guang et…”

Separation of Olivine Crystals and Borate Containing Slag from CaO–SiO₂–B₂O₃–MgO–Al₂O₃ System by Utilizing Super-Gravity

“…Considering olivine was the first precipitate from boronbearing slag with temperature decreasing based on B 2 O 3 -MgO-SiO 2 phase diagram, while kotoite and suanite precipitated at lower temperatures and uniformly distributed among the first precipitated olivine, [5][6][7][8][9][10][11] the separation of olivine precipitate and borate containing slag thus would be another feasible choice for recovering boron from the slag. Consequently, the precipitation behavior of olivine in CaO-SiO 2 -B 2 O 3 -MgO-Al 2 O 3 system was investigated, and then the separation of olivine crystals and borate containing slag melt by utilizing super-gravity was conducted in current study, which under the inspiration of successful application of super-gravity on some other melts.…”

Melting Separation Behavior and Mechanism of High-chromium Vanadium–bearing Titanomagnetite Metallized Pellet Got from Gas-based Direct Reduction

“…4,9) Recently, the processes of coal-based direct reduction followed by electric furnace smelting or magnetic separation have gained increasing attention as alternative routes to dispose the special metallurgical resources besides VT and HCVT. [5][6][7][10][11][12][13][14] Shuangying et al 7) has studied the process of metalizing reduction and magnetic separation for vanadium titano-magnetite, by which the vanadium is enriched in the titanium-bearing slag and the recovery ratios of Fe, V, and Ti are 91.19%, 61.82%, and 85.31%, respectively. In Longsheng et al's researches, 13) most of V, Cr, and Ti are concentrated into slag by the process of coal-based reduction-magnetic separation for HCVT, and the recoveries of V, Cr, and Ti are only about 40%, 80%, and 20%, respectively.…”