Steel before or during the blowing steelmaking pig iron containing vanadium, vanadium slag obtained. The vanadium slag produced by atomization of vanadium before steelmaking is called atomized vanadium slag. It is characterized by high vanadium content, but high iron content, while impurities such as calcium are low. The content of impurities such as calcium, phosphorus and silicon in the slag produced during the vanadium-bearing pig iron steel making process is relatively high. At present, vanadium slag produced in South Africa, Russia and China is basically atomized vanadium slag.
I. Former Soviet Union Chusov Factory
The process is shown in Figure 1.
Figure 1 Wet process of the former Soviet Union Chusov plant
(1) Removal of iron: first remove the large piece of iron by hand, then grind it to 1.0mm, and magnetically separate the iron particles;
(2) Sodium oxide roasting: with sodiuming agent Na 2 CO 3 , NaCl, Na 2 SO 4 , calcined at 850-950 ° C, the rotary kiln used is 2.5 m in diameter, 42 m long, and the processing capacity is 2500-3200 kg/ h. The water-soluble dip leaching rate of vanadium after calcination is 85% to 92%.
(3) Leaching: firstly add water immersion, liquid-solid ratio 3.5/1, 40-50 ° C, and the residue after filtration contains 0.6% V 2 O 5 , and sent to the second step to add acid leaching.
(4) Shen vanadium: using acidic hydrolysis to form vanadium, to obtain red cake. Finally, the melt contains 89% to 90% of V 2 O 5 .
Second, Yantie Alloy Factory
The process used for atomizing vanadium slag of Panzhihua Steel Plant is shown in Figure 2.
FIG 2 emei iron alloy vanadium process plant
Grain size of vanadium slag | 20 mesh | 60 mesh | 80 mesh | 100 mesh |
Screen residue /% | twenty three | 31.2 | 47.9 | 55.8 |
Vanadium slag composition: | V 2 O 5 | Fe | SiO 2 | Al 2 O 3 |
content/% | 15.08 | 44.03 | 11.86 | 3.52 |
(1) Reagents: soda ash, Na 2 CO 3 98%; ammonium sulfate, industrial products; thenardite , Na 2 SO 4 98%; sulfuric acid, industrial products; calcium chloride, industrial products.
(2) Leaching and purifying: immersed in wet ball mill and added CaCl 2 to remove phosphorus, and brighten it to 0.5~1.5kg/m3 solution. The components of the solution after purification are shown in Table 1.
Table 1 Liquid component (g/L) after purification of atomized vanadium slag from Panzhihua Iron and Steel Co., Ltd.
Sample number | V | P | Si | Fe | K 2 O | Na 2 O | pH value | Note |
1 | 7.7 | 0.0077 | 0.27 | 0.00136 | 0.019 | 7.3 | 9.5 | Secondary slag |
3 | 15.7 | 0.0076 | 0.27 | 0.0032 | 0.0048 | 31.9 | 9.5 | Secondary slag |
(3) Shen vanadium: The equipment used is mechanical stirring tank, the speed is 16r/min, direct steam heating, firstly enter the quantitative purification liquid, then slowly add sulfuric acid, adjust the pH to 2~3 and then add ammonium sulfate, steam Heating to 85 ° C, 60 min, sulfuric acid addition coefficient is 1 ~ 1.3. The vanadium end point is controlled in the supernatant containing vanadium below 0.1g/L. The vanadium precipitation rate is 99%, and the ammonium vanadate fuse contains V 2 O 5 98% or more.
Since the ammonium polyvanadate precipitate entrains about 50% of free water, it should be washed with 1% to 2% ammonium sulfate solution to remove Na 2 O in free water.
(4) Deamination and melting of ammonium polyvanadate: The melting is carried out in a 12 m3 water-cooled melting furnace. Coal for fuel gas, a first thermal decomposition stage 600 ℃, the second stage is 800 ~ 900 ℃. The composition of the V 2 O 5 fuse is shown in Table 2.
Table 2 Composition of V 2 O 5 Fuses (%)
Stove number | V 2 O 5 | SiO 2 | Fe | P | S | As | K 2 O | Na 2 O |
3 | 98.87 | 0.275 | 0.269 | 0.0274 | 0.0163 | 0.00185 | 0.12 | 0.96 |
72 | 99.5 | 0.15 | 0.197 | 0.0181 | 0.0059 | 0.055 | 0.389 |
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