Effective Chromium Extraction from Chromium-containing Vanadium Slag by Sodium Roasting and Water Leaching

Abstract

Chromium (Cr) was concentrated as chromium spinel in the vanadium slag produced by pre-oxidizing vanadium-containing hot metal in Pan-steel in China. Due to the chromium-rich Hongge ores used, chromium concentration in this slag was much higher than that in common vanadium slags. To propose a process for effective Cr extraction from the slag, mechanisms of Cr oxidation in Pan-steel vanadium slag under sodium roasting conditions were studied experimentally and with thermodynamic simulations. Chromium slags without vanadium were synthesized in the laboratory to mimick mineralogical characteristics of Pan-steel vanadium slag and characterized by XRD, SEM/EDS and TG-DSC techniques. Conditions for Cr extraction from the chromium slag after sodium roasting by leaching with water were studied and optimized. Results showed that Cr spinel was encapsulated in the silicate phase. During sodium roasting, Cr spinel was oxidized and decomposed after oxidation and decomposition of the olivine phase. Sodium carbonate began to react with chromium oxide, which was produced by decomposition of Cr spinel, at 537°C and large amount of sodium chromate appeared after 800°C. However, multi-component liquid phase (mixture of Na2Cr2O4, Na2CrO4 and Na2CO3) was produced after 1 000°C, which suppressed the conversion of Cr(III) to Cr(VI) by inhibiting oxygen supply. A conversion about 90% was obtained when the chromium slag was roasted at 1 000°C for 2 h with Na2CO3 addition in stoichiometric ratio to total amount of Cr2O3 and SiO2. 96% of Cr in the leaching liquid was recovered as chromium sesquioxide in fine powder form and high purity by reducing and precipitating.

Viscosity Property and Structure Analysis of FeO–SiO₂–V₂O₃–TiO₂–Cr₂O₃ Slags

“…With the gradual consumption of high quality VTM, the low-grade bearing chromium VTM (namely the Hongge type V-bearing titanomagnetite, with an approximate composition of 45.5 mass% T.Fe, 10.6 mass% TiO 2 , 0.4 mass% V 2 O 5 , and 0.2 mass% Cr 2 O 3 ) [6][7][8] has caused much attention and is beginning to be utilized in recent years. It is reported that the proven reserves of Hongge type V-bearing titanomagnetite is about 2.0 billion tons in Panxi and Chengde regions of China.…”

Investigation of Reaction Mechanism on the Lime-Free Roasting of Chromium-Containing Slag

“…The greatest weight loss can be observed in the temperature range of 920 K to 1010 K (647°C to 737°C), which indicates that Na 2 CO 3 reacted with Fe 2 O 3 and Cr 2 O 3 via Eqs. [4] and [9].…”

“…In the Hongge Mine Area, located at the boundary of Panzhihua City and Xichang City, the minerals not only contain iron, titanium, and vanadium, but the chromium content is also relatively rich (0.2-0.8 pct). [4] At present, the vanadiferous titanomagnetite minerals are firstly used to produce titanium slag and vanadiferous hot metal by smelting in a blast furnace. [5][6][7] Then in a rotary furnace, the vanadium steel slag is separated from the vanadiferous hot metal by a special blowing process.…”

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

“…According to the prediction model derived by Tanaka et al 25) and the research on the surface tension of molten blast furnace slag bearing TiO 2 , 26) Cation and R i Anion is the radium of cation and anion respectively, m; N i P is the mole fraction of component i in phase P, -; P is Surf (surface) or Bulk (bulk). In addition, SO 4 4 − is thought to be the minimum anionic unit in SiO 2 and the ratio of R Si 4+ to R SiO 4 4− is 0.5.…”

“…1) In VT, there are various valuable elements including iron, titanium, vanadium, and chromium which are typical strategic resources due to its extensive application in metallurgy, chemical industry, and aerospace etc. [2][3][4] Based on the mass fraction of Cr 2 O 3 , VT is classified into two categories: ordinary VT and high chromium vanadiumbearing titanomagnetite (HCVT), and HCVT has a higher comprehensive utilization value. 2) At present, VT is smelt in blast furnace (BF) but the recovery rate of Fe, V, and TiO 2 is only reach 70%, 39% and 13% respectively.…”