Phases Transition and Consolidation Mechanism of High Chromium Vanadium-Titanium Magnetite Pellet by Oxidation Process

2016 ◽  
Vol 35 (7) ◽  
pp. 729-738
Author(s):  
Jue Tang ◽  
Man-sheng Chu ◽  
Cong Feng ◽  
Feng Li ◽  
Zheng-gen Liu
Keyword(s):  
Phase Transition ◽  
Oxidation Process ◽  
Consolidation Process ◽  
High Chromium ◽  
Oxidized Pellet ◽  
Three Stages ◽  
Roasting Temperature ◽  
Vanadium Titanium ◽  
Roasting Time ◽  
Titanium Magnetite

AbstractBased on the fundamental characteristics of high chromium vanadium-titanium magnetite (HCVTM), the effects of roasting temperature and roasting time on the phase transition and oxidation consolidation during the oxidation were investigated systematically. It was shown that the oxidation of HCVTM pellet was not a simple process but complex. With increasing roasting temperature and time, the compressive strength of oxidized pellet was improved. The phase transition during oxidation was hypothesized to proceed as follows: (1) Fe3O4 → Fe2O3; (2) Fe2.75Ti0.25O4 → Fe9TiO15 + FeTiO3 → Fe9TiO15 + Fe2Ti3O9; (3) Fe2VO4 → V2O3 → (Cr0.15V0.85)2O3; (4) FeCr2O4 → Cr2O3 → Cr1.3Fe0.7O3 + (Cr0.15V0.85)2O3. The oxidation consolidation process was divided into three stages: (1)oxidation below 1,173 K; (2) recrystallization consolidation at 1,173 – 1,373 K; (3) particle refining recrystallization-consolidation by the participation of liquid phase at 1,373 – 1,573 K. To obtain the HCVTM oxidized pellet with good quality, the rational roasting parameters included a roasting temperature of 1,573 K and a roasting time of 20 min.

Effective Extraction of Vanadium and Chromium from High Chromium Content Vanadium Slag by Sodium Roasting and Water Leaching

2016 ◽  
Vol 863 ◽  
pp. 144-148 ◽  
Author(s):  
Ming Li ◽  
Liang Xiao ◽  
Jing Jing Liu ◽  
Zhi Xin Shi ◽  
Zi Bi Fu ◽  
...  
Keyword(s):  
Chromium Content ◽  
Leaching Rate ◽  
Vanadium Slag ◽  
Water Leaching ◽  
Sodium Salts ◽  
High Chromium ◽  
Effective Factor ◽  
Roasting Process ◽  
Roasting Temperature ◽  
Roasting Time

The extraction of vanadium and chromium from high chromium content vanadium slag by salt roasting and water leaching process has been investigated, which uses mixed sodium salts (Na2CO3 and NaOH) as additive agent in roasting process. The mineralogical morphology was prospected by TG-DSC, XRD, SEM and EDS. The oxidation of slag and transversion of V/Cr-containing phase and sodium salts have been discussed. It has been demonstrated that the presence of NaOH contributes to decompose spinel and olivine phases, which is beneficial to reduce the roasting temperature and elevate V, Cr leaching ratio. The roasting parameters have been studied as a function of roasting temperature, roasting time and ratio of alkali, in which the roasting temperature is the most effective factor on the leaching rate of vanadium and chromium. Under the optimum condition, the leaching rates of V and Cr reached 95.8% and 97.6%, respectively.

Microwave Roasting and Acid Leaching of Vanadium and Chromium from High Chromium Vanadium Slag with CaCO3

2019 ◽  
Vol 294 ◽  
pp. 86-91
Author(s):  
Hui Yang Gao ◽  
Tao Jiang ◽  
Ying Zhe Xu
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Vanadium Slag ◽  
Sulfuric Acid Leaching ◽  
High Chromium ◽  
Microwave Roasting ◽  
Roasting Process ◽  
Roasting Temperature ◽  
Irradiation Technology ◽  
Roasting Time

In this study, microwave irradiation technology was used for the calcification roasting followed by sulfuric acid leaching process. The effect of roasting temperature, m (CaO)/m (V2O5), and roasting time on the leaching ratio of vanadium were investigated and the roasted samples were characterized by TG-DSC, XRD, and SEM. The leaching ratio of vanadium can be significantly enhanced with the increasing in roasting temperature, m (CaO)/m (V2O5), and roasting time. The leaching ratio of chromium decreased with roasting temperature and increased with m (CaO)/m (V2O5), and roasting time. The optimal roasting parameters were roasting temperature of 850 °C, the m (CaO)/m (V2O5) of 0.85, and roasting time of 90 min. Under the optimal roasting parameters, the leaching ratio of vanadium reached 88.81%. While the leaching ratio of chromium is 3.98%. During roasting process, vanadium is oxidized to acid-soluble CaV2O5, Ca2V2O7, and CaMgV2O7. After leaching, chromium mainly exists in form of chromohercynite (FeCr2O4) and chrome-manganese spinel (Mn1.5Cr1.5O4) in leaching residues.

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