To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the...To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti Nb-bearing Fe concentrate/coal composite pel- let was reduced at temperatures greater than 1100℃. The addition of CaCO3 improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100~C were analyzed by X-ray diffraction and scanning electron microsco- py-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100℃ for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet.展开更多
The phenomenon of crystallization was implemented in the synthetic V-bearing steelwork slag based on the composition of factory slag from the Masteel Co., and the possibility of undercooling as a technique to precipit...The phenomenon of crystallization was implemented in the synthetic V-bearing steelwork slag based on the composition of factory slag from the Masteel Co., and the possibility of undercooling as a technique to precipitate V-concentration phase was demonstrated. The effect of 20wt% Al_2O_3 additive introduced into the slag on intensifing the precipitation was also investigated. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) were used to investigate the slag after heat treatment. It is demonstrated that gehlenite and grossite are the major crystalline phases. Whitlockite with a high content of V_2O_5 (called V-concentration phase hereafter) nucleates homogeneously and hetergeneously and grows with decreasing undercooling. At 1548 K, the crystals of V-concentration phase grow up as the duration of time, with a medium grain size of 25 μm at 300 min holding time.展开更多
The mechanism of improving compressive strength of magnetite pellet by adding boron-bearing iron concentrate was studied. Boron-bearing iron concentrate and magnetite were mixed, pelletized and roasted under differ en...The mechanism of improving compressive strength of magnetite pellet by adding boron-bearing iron concentrate was studied. Boron-bearing iron concentrate and magnetite were mixed, pelletized and roasted under differ ent roasting conditions. Then, compressive strength of pellets was tested, and polished sections of the roasted pellets were analyzed from the perspective of mineralogy. Finally, the effects of different proportions, roasting temperatures and roasting time of boron-bearing iron concentrate on the compressive strength of magnetite pellets were investigated and explained.展开更多
Realizing the boron and iron separation through selective reduction and melting separation of boron-bearing iron con- centrate is of great significance for the utilization of crude ludwigite. The reduction and melting...Realizing the boron and iron separation through selective reduction and melting separation of boron-bearing iron con- centrate is of great significance for the utilization of crude ludwigite. The reduction and melting separation mechanism of boron-bearing iron concentrate/coal composite pellet was systematically investigated. The reduction and melting separation test of small size pellet was performed to reveal the evolution of slag and iron in the melting separation process. The isothermal reduction experiment showed the relationship between reduction stage and melting separation stage, and the step reduction and melting separation was perfectly achieved. Coal particles existed through the reduction and melting separation process and finally formed brown residue around the separated product. The pellet could not realize melting separation when the B2O3 content in the concentrate was lower than 6.00 wt%.展开更多
基金financial support of the Fundamental Research Funds for the Central Universities (FRF-TP-16-019A1)the State Key Laboratory of Advanced Metallurgy (41617007), University of Science and Technology Beijing
文摘To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti Nb-bearing Fe concentrate/coal composite pel- let was reduced at temperatures greater than 1100℃. The addition of CaCO3 improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100~C were analyzed by X-ray diffraction and scanning electron microsco- py-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100℃ for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet.
文摘The phenomenon of crystallization was implemented in the synthetic V-bearing steelwork slag based on the composition of factory slag from the Masteel Co., and the possibility of undercooling as a technique to precipitate V-concentration phase was demonstrated. The effect of 20wt% Al_2O_3 additive introduced into the slag on intensifing the precipitation was also investigated. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) were used to investigate the slag after heat treatment. It is demonstrated that gehlenite and grossite are the major crystalline phases. Whitlockite with a high content of V_2O_5 (called V-concentration phase hereafter) nucleates homogeneously and hetergeneously and grows with decreasing undercooling. At 1548 K, the crystals of V-concentration phase grow up as the duration of time, with a medium grain size of 25 μm at 300 min holding time.
基金Item Sponsored by National Natural Science Foundation of China(51204013)Fundamental Research Funds for Central Universities of China(FRF-TP-12-020A)
文摘The mechanism of improving compressive strength of magnetite pellet by adding boron-bearing iron concentrate was studied. Boron-bearing iron concentrate and magnetite were mixed, pelletized and roasted under differ ent roasting conditions. Then, compressive strength of pellets was tested, and polished sections of the roasted pellets were analyzed from the perspective of mineralogy. Finally, the effects of different proportions, roasting temperatures and roasting time of boron-bearing iron concentrate on the compressive strength of magnetite pellets were investigated and explained.
基金The authors would like to express their gratitude for the financial support of the China Postdoctoral Science Foundation （No. 2016M600919） and National Natural Science Foundation of China （No. 51274033）.
文摘Realizing the boron and iron separation through selective reduction and melting separation of boron-bearing iron con- centrate is of great significance for the utilization of crude ludwigite. The reduction and melting separation mechanism of boron-bearing iron concentrate/coal composite pellet was systematically investigated. The reduction and melting separation test of small size pellet was performed to reveal the evolution of slag and iron in the melting separation process. The isothermal reduction experiment showed the relationship between reduction stage and melting separation stage, and the step reduction and melting separation was perfectly achieved. Coal particles existed through the reduction and melting separation process and finally formed brown residue around the separated product. The pellet could not realize melting separation when the B2O3 content in the concentrate was lower than 6.00 wt%.
