CN108359818A - Converter segmented supplies extraction vanadium method - Google Patents

Abstract

The invention discloses a method for extracting vanadium by segmented gas supply in a converter, which belongs to the field of iron and steel smelting. The present invention provides a novel converter vanadium extraction method for solving the problems of large coolant consumption, high cost, high carbon oxidation rate and low vanadium oxidation rate in the production process of a vanadium extraction workshop in a steelmaking plant. The method comprises the following steps: containing vanadium After the molten iron enters the converter, it is blown by blowing gas through an oxygen lance, and the position of the oxygen lance is constant during blowing; from the beginning of blowing to blowing 2.5 to 3.0 minutes, oxygen is used for blowing; then nitrogen is used for blowing, blowing The time is 2.0-3.0 minutes; and then oxygen is used for blowing, and the blowing time is 2.0-2.5 minutes to obtain vanadium slag and semi-steel. The method of the invention can significantly reduce the amount of coolant for vanadium extraction, increase the oxidation rate of vanadium, reduce the oxidation rate of carbon, and is beneficial to the full utilization of resources and the reduction of the production cost of vanadium extraction.

Description

Method for Extracting Vanadium by Converter Segmented Gas Supply

technical field

The invention belongs to the field of iron and steel smelting, and in particular relates to a method for extracting vanadium by supplying gas in stages in a converter.

Background technique

my country is a big country of vanadium-titanium magnetite. Enterprises such as Panzhihua Iron and Steel, Chenggang, Kunming Iron and Steel, and Weiyang Iron and Steel all use vanadium-titanium magnetite for smelting. The vanadium content of molten iron smelted from vanadium-titanium magnetite blast furnace is compared with that of ordinary molten iron. High, and vanadium is an important resource, so vanadium must be extracted before molten iron steelmaking to produce vanadium slag. At present, there are many production methods for producing vanadium slag at home and abroad, mainly including the ladle blowing vanadium process in New Zealand, the vanadium extraction process in South Africa, and the converter vanadium extraction process in Russia and China. Other vanadium extraction processes include vanadium-containing steel slag extraction process. Vanadium, stone coal vanadium extraction process, etc. Among them, the converter vanadium extraction process is the best, and the technical and economic indicators are the best.

The production process system of converter vanadium extraction at home and abroad is the continuous improvement of adding coolant + process temperature + blowing time. Vanadium extraction from hot metal is a selective oxidation technology. Vanadium extraction by converter gas supply is an exothermic process. The oxidation of [Si], [Mn], [V], [C] and other elements makes the molten pool heat up rapidly, while the oxidation of [Si] and [Mn] occurs at the time of [V] oxidation. Before, vanadium extraction could not inhibit its reaction, and the conversion temperature of [C] and [V] was about 1385°C, so to obtain high oxidation rate of [V] and [V] yield, vanadium extraction coolant must be added, Control the molten pool temperature to make it close to [C], [V] conversion temperature, achieve the purpose of extracting vanadium and preserving carbon, and reduce [V] to less than 0.05%. The semi-steel temperature at the end of vanadium extraction should not be too high. The vanadium extraction process is dominated by vanadium oxidation in the early stage and vanadium reduction in the later stage, but the vanadium blowing process is dominated by vanadium reduction. Therefore, the method of cooling is to add coolant to lower the temperature of molten iron to an appropriate range. In converter smelting, through the control of blowing time and process temperature, the vanadium in the semi-steel is oxidized to increase the yield.

CN1789435 discloses a coolant for extracting vanadium and controlling calcium from molten iron and a process for extracting vanadium and controlling calcium from molten iron. The chemical composition (Wt%) of the coolant for extracting vanadium is: 56-60% of iron oxide scale, 30-40% of iron concentrate powder, Binder 5-10%, the coolant can increase the extraction rate of vanadium and the grade of vanadium slag, and stabilize the calcium oxide content of vanadium slag; it is only optimized from the vanadium extraction coolant composition, and does not involve the optimization of blowing gas. CN101338351 discloses a vanadium extracting coolant and its preparation method and use method. The coolant is produced from iron oxide scale or vanadium extracting sludge, vanadium-containing iron concentrate, and binder, and contains 80%-95% iron oxide 3-6% SiO ₂ , 0.1-0.6% V ₂ O ₅ , 1-3% MgCl ₂ ; it also only involves the composition adjustment of the vanadium extraction coolant, and does not involve the adjustment of the blowing gas. CN 103924027B discloses a method for extracting vanadium and making steel. The method includes a blowing vanadium extracting process, a semi-steel removing process, and an exothermic agent adding process. The relationship between surface distance H and time is as follows: from the beginning of blowing to 1.5 minutes of blowing, H=1.8m~2.0m; from 1.5 minutes of blowing to 40s before the end of blowing, H=1.6m~1.8m, from 40s to At the end of blowing, H=1.3m~1.6m; when the vanadium extraction furnace is a 70-ton converter, the oxygen lance adopts a 3-hole Laval oxygen lance, the oxygen flow rate is set at 13000Nm ³ /h, and the oxygen pressure is 0.75-0.80Mpa; When the vanadium furnace is a 120-ton converter, the oxygen lance adopts a 4-hole Laval oxygen lance, the throat diameter of the oxygen lance is 30.3mm, the oxygen flow rate is set to 16000Nm ³ /h, and the oxygen pressure is 0.80-0.85Mpa; the exothermic agent is added to the process , when 1/3 of the semi-steel of the vanadium extraction furnace enters the ladle, the heating agent is added to the ladle. Position control, and no mention is made of the method of controlling different blown gases at different smelting stages. Most of the existing technologies only adjust the coolant or gun position, and do not pay attention to the research on the blowing gas which is very important for temperature control.

Contents of the invention

The technical problem to be solved by the present invention is to provide a novel converter vanadium extraction method to solve the problems of large coolant consumption, high cost, high carbon oxidation rate and low vanadium oxidation rate in the production process of the vanadium extraction workshop of the steelmaking plant.

The technical means adopted by the present invention to solve the above-mentioned technical problems is to provide a method for extracting vanadium by means of a converter staged gas supply, the method comprising the following steps:

a. After the vanadium-containing molten iron enters the converter, blowing gas is carried out through the oxygen lance, and the position of the oxygen lance remains constant during blowing;

b. The blowing process is divided into three stages, from the beginning of blowing to blowing 2.5 ~ 3.0min is the first stage, the first stage uses oxygen for blowing;

c. After the first stage is over, continue blowing for 2.0-3.0 minutes. This process is the second stage, and nitrogen is used for blowing in the second stage;

d. At the end of the second stage, continue blowing for 2.0 to 2.5 minutes. This process is the third stage, and the third stage uses oxygen for blowing;

e. At the end of the third stage, vanadium slag and semi-steel are obtained.

Wherein, in the step-wise method for extracting vanadium by means of converter gas supply described above, in step a, the position of the oxygen lance is 1.7-2.0 m.

Wherein, in the method for extracting vanadium by the above-mentioned converter staged gas supply, in step b, the pressure of the oxygen in the first stage is 0.70-0.85MPa, and the gas supply intensity is 3.2-4.0m ³ /(min·t vanadium-containing molten iron).

Wherein, in the stepwise method for extracting vanadium by converter gas supply described above, in step b, the coolant is added at 0.5-1.0 min before the end of the first stage.

Wherein, in the step-wise method for extracting vanadium by means of converter gas supply described above, in step b, the amount of the coolant used is no more than 20 kg/t of vanadium-containing molten iron.

Wherein, in the stepwise method for extracting vanadium by converter gas supply, in step b, the coolant is a low-sulfur and low-phosphorus material containing iron and iron oxides, and its composition includes TFe>50%.

Preferably, in the above-mentioned stepwise method for extracting vanadium by converter gas supply, in step b, the coolant is at least one of pig iron block, iron oxide scale or ore.

Wherein, in the stepwise method for extracting vanadium by converter gas supply described above, in step c, the nitrogen pressure in the second stage is 0.75-0.90 MPa, and the gas supply intensity is 2.5-3.5m ³ /(min·t vanadium-containing molten iron).

Wherein, in the stepwise method for extracting vanadium by converter gas supply described above, in step d, the pressure of oxygen in the third stage is 0.70-0.85MPa, and the gas supply intensity is 3.2-4.0m ³ /(min·t vanadium-containing molten iron).

Wherein, in the stepwise method for extracting vanadium by means of a converter with gas supply, the converter is a top-bottom double-blown vanadium converter or a top-blown oxygen converter.

Wherein, in the method for extracting vanadium in the above-mentioned converter segmented gas supply method, when the converter is a top-bottom combined blowing vanadium converter, the bottom blowing gas supply intensity is controlled to be 0.001-0.003m ³ /(min· t vanadium-containing molten iron), and during blowing, the supply intensity of the bottom blowing gas is controlled to be 0.35-0.65m ³ /(min·t vanadium-containing molten iron); the bottom blowing gas is nitrogen.

The beneficial effects of the present invention are:

The method of the present invention divides the blowing period into three stages. By controlling the type, pressure and flow rate of the blowing gas in the three stages, and controlling the blowing time of each stage, the amount of vanadium extraction coolant can be significantly reduced, and the amount of vanadium extraction can be increased. High oxidation rate and reduced carbon oxidation rate are conducive to the full utilization of resources and the reduction of production costs for vanadium extraction.

Detailed ways

Concretely, a method for extracting vanadium by staged gas supply in a converter comprises the following steps:

a. After the vanadium-containing molten iron enters the converter, blowing gas is carried out through the oxygen lance, and the position of the oxygen lance remains constant during blowing;

b. The blowing process is divided into three stages, from the beginning of blowing to blowing 2.5 ~ 3.0min is the first stage, the first stage uses oxygen for blowing;

c. After the first stage is over, continue blowing for 2.0-3.0 minutes. This process is the second stage, and nitrogen is used for blowing in the second stage;

d. At the end of the second stage, continue blowing for 2.0 to 2.5 minutes. This process is the third stage, and the third stage uses oxygen for blowing;

e. At the end of the third stage, vanadium slag and semi-steel are obtained.

When the oxygen lance is supplied with air in the present invention, the gun position is controlled by a constant gun position mode, that is, the same gun position is used during blowing, and the gun position is controlled at a distance of 1.7 to 2.0 m from the metal liquid surface.

In the original converter vanadium extraction process, the oxidizing atmosphere in the furnace is controlled by adjusting the position of the gun during the gas blowing process, and at the same time adding a coolant to control the temperature to ensure that the vanadium in the iron water is oxidized within a suitable temperature range; however, in this process The oxidizing atmosphere in the intermediate furnace is still relatively high, which makes the content of FeO in the slag relatively high, and the temperature control fluctuates greatly, resulting in a large loss of carbon during the vanadium extraction process.

The method of the present invention combines the temperature rise process and reaction law of vanadium extraction in converter, and aims at the characteristics of rapid temperature rise in the early stage of oxygen blowing vanadium extraction technology, and divides the blowing period into three stages: the first stage is from the beginning of blowing to blowing 2.5~3.0min, during which the oxygen pressure is controlled to be 0.70~0.85MPa, the gas supply intensity is 3.2~4.0m ³ /(min·t vanadium-containing molten iron), and the coolant is added 0.5~1.0min before the end of the first stage , to ensure that there is a stirring time of >30s after the addition. In the early stage, pure oxygen is used for blowing, most of the vanadium is oxidized, and the coolant is melted; the first stage is over, and the second stage is blown with nitrogen to control the pressure of nitrogen 0.75~0.90MPa, the gas supply intensity is 2.5~3.5m ³ /(min·t vanadium-containing molten iron), the blowing time is 2.0~3.0min, and pure nitrogen is used for blowing and stirring in the middle stage, so as to avoid the continuous impact of oxygen on iron The oxidation of carbon and iron in the water can effectively control the temperature in the furnace. At the same time, the FeO in the slag can continue to oxidize the vanadium in the iron water to increase the oxidation rate of vanadium. The pressure is 0.70~0.85MPa, the gas supply intensity is 3.2~4.0m ³ /(min·t vanadium-containing molten iron), the blowing time is 2.0~2.5min, and pure oxygen is used for blowing in the later stage to ensure the slag iron in the converter. Separation, heating by pure oxygen blowing, effectively reducing the consumption of steel materials.

In order to ensure that the iron oxide in the coolant can oxidize the vanadium in the iron water during the nitrogen blowing and stirring process, the method of the present invention is required to be added 0.5 to 1.0 min before the end of the first stage, so that the furnace can be controlled in the early stage of the fastest temperature rise The internal temperature is around 1320°C, in order to reduce the burning loss of carbon, and at the same time, there is a certain period of time to promote the melting of the coolant to ensure that the slag-gold reaction in the nitrogen blowing process is carried out; the vanadium extraction coolant described in the present invention can be commonly used in this field. The coolant for extracting vanadium is TFe>50% low-sulfur and low-phosphorus material containing iron and iron oxides, such as at least one of pig iron block, iron oxide scale, ore, etc.; Nitrogen is an inert gas, which not only does not raise the temperature of molten iron oxide, but also takes away the temperature in the furnace, so it can greatly reduce the amount of coolant for vanadium extraction. The amount of coolant for vanadium extraction is not more than 20g/t Vanadium-containing molten iron.

The method of the present invention is particularly suitable for top-bottom double-blowing vanadium-extraction converters or top-blown oxygen converters; when the converter is a top-bottom double-blowing vanadium-extraction converter, the gas supply intensity of bottom blowing gas is controlled to be 0.001-0.003m ³ /( min·t vanadium-containing molten iron), reduce bottom blowing in the non-converting stage to avoid excessive temperature drop in the furnace; control the bottom blowing gas supply intensity during blowing to 0.35-0.65m ³ /(min·t vanadium-containing molten iron) During the blowing period, increasing the flow rate and bottom blowing can improve the stirring ability of the bottom blowing; the bottom blowing gas is nitrogen; the non-blowing period is the idle time between the completion of semi-steel and the next blowing.

The present invention will be further described in detail through the examples below, but the protection scope of the present invention is not limited to the scope of the examples.

Example 1

After the molten iron enters the 200t re-blowing converter, during the blowing period, the gun position is kept constant at a distance of 1.7m from the metal liquid surface for blowing; the blowing process is divided into three stages, the first stage uses pure oxygen for blowing, and the oxygen pressure is controlled at 0.70MPa, the gas supply intensity is controlled at 3.2m ³ /(min·t vanadium-containing molten iron), the blowing time is 3.0min, the coolant is added at 2.5min of blowing, and the addition amount is 17kg/t vanadium-containing molten iron; the first At the end of the stage, nitrogen is used for blowing in the second stage, the nitrogen pressure is controlled at 0.90MPa, the gas supply intensity is controlled at 3.5m ³ /(min·t molten iron containing vanadium), and the blowing time is 2.0min; In the third stage, pure oxygen is used for blowing, the oxygen pressure is controlled at 0.85MPa, the gas supply intensity is controlled at 4.0m ³ /(min·t molten iron containing vanadium), and the blowing time is 2.5min; the flow rate of bottom blowing gas in the non-blowing stage is controlled At 0.001m ³ /(min·t vanadium-containing molten iron), the blowing period is controlled by 0.5m ³ /(min·t vanadium-containing molten iron), and the bottom blowing gas is nitrogen; at the end of the third stage, vanadium slag and semi-steel After testing, the vanadium oxidation rate of molten iron reached 92.32%, and the carbon oxidation rate was 11.34%.

Example 2

After the molten iron enters the 200t converter, a top-blown oxygen lance is used for gas injection, and the position of the lance is constantly controlled at a distance of 2.0m from the liquid metal surface; the blowing process is divided into three stages, the first stage uses pure oxygen for blowing, and the oxygen pressure Controlled at 0.85MPa, air supply intensity controlled at 4.0m ³ /(min·t vanadium-containing molten iron), blowing time is 2.5min, coolant is added at 2.0min of blowing, and the addition amount is 18kg/t vanadium-containing molten iron; The first stage ends, the second stage uses nitrogen for blowing, the nitrogen pressure is controlled at 0.75MPa, the gas supply intensity is controlled at 2.5m ³ /(min·t vanadium-containing molten iron), and the blowing time is 3.0min; the second stage ends , the third stage uses pure oxygen for blowing, the oxygen pressure is controlled at 0.70MPa, the gas supply intensity is controlled at 3.2m ³ /(min·t molten iron containing vanadium), and the blowing time is 2.0min; at the end of the third stage, half Steel and vanadium slag, after testing, the vanadium oxidation rate of molten iron has reached 91.18%, and the carbon oxidation rate has reached 11.23%.

Example 3

After the molten iron enters the 120t converter, a top-blown oxygen lance is used for gas injection, and the position of the lance is constantly controlled at a distance of 1.9m from the metal liquid surface; the blowing process is divided into three stages, the first stage uses pure oxygen for blowing, and the oxygen pressure Controlled at 0.80MPa, air supply intensity controlled at 3.5m ³ /(min·t vanadium-containing molten iron), blowing time is 2.7min, coolant is added at 2.0min of blowing, and the addition amount is 16kg/t vanadium-containing molten iron; The first stage ends, the second stage uses nitrogen for blowing, the nitrogen pressure is controlled at 0.80MPa, the gas supply intensity is controlled at 2.6m ³ /(min·t vanadium-containing molten iron), and the blowing time is 2.5min; the second stage ends , the third stage uses pure oxygen for blowing, the oxygen pressure is controlled at 0.8MPa, the gas supply intensity is controlled at 3.8m ³ /(min·t molten iron containing vanadium), and the blowing time is 2.2min; at the end of the third stage, half Steel and vanadium slag, after testing, the vanadium oxidation rate of molten iron is 94.16%, and the carbon oxidation rate is 13.73%.

Comparative example 1

After the molten iron enters the 200t converter, the oxygen lance is used to blow oxygen; when the oxygen lance is supplied with air, the lance position is controlled by the "high-low-high" mode, that is, the lance position is 1.9m (the height between the nozzle and the liquid surface) for 1 minute in the early stage of blowing. ), adopt a 1.6m low lance position in the mid-term, adopt a 1.9m high lance position 1.5 minutes before the end of blowing, and control the gas supply intensity at 2.0m ³ /(min·t molten iron containing vanadium); use 0.2m ³ /( The gas supply intensity of vanadium-containing molten iron (min·t) is controlled by bottom blowing nitrogen; vanadium extraction coolant is added 2.5 minutes before blowing, and the added amount is 32g/t vanadium-containing molten iron. The vanadium oxidation rate of molten iron is 84.36%, and the carbon oxidation rate is 15.71%.

Comparative example 2

After the molten iron enters the 120t converter, the oxygen lance is used to blow oxygen; when the oxygen lance is supplied with air, the lance position is controlled by the "high-low-high" mode, that is, the 1.8m lance position is used for the first 1.5 minutes of blowing (the distance between the nozzle and the liquid surface) Height), 1.5m low lance position is used in the mid-term, 1.8m high lance position is adopted 1 minute before the end of blowing, and the gas supply intensity is controlled at 1.8m ³ /(min·t molten iron containing vanadium); 0.25m ³ /( The gas supply intensity of min·t vanadium-containing molten iron) is controlled by bottom blowing nitrogen; the vanadium extraction coolant is added 3 minutes before blowing, and the addition amount is 28g/t vanadium-containing molten iron. The vanadium oxidation rate of molten iron is 83.47%, and the carbon oxidation rate is 16.18%.

From Examples 1 to 3 and Comparative Examples 1 to 2, it can be known that the method of the present invention can significantly improve the performance of the blowing process by controlling the type, pressure and flow rate of the blowing gas in three stages during blowing, and controlling the blowing time of each stage. The amount of vanadium extraction coolant is reduced, the oxidation rate of vanadium is increased, and the oxidation rate of carbon is reduced, thereby realizing full utilization of resources and reduction of production cost of vanadium extraction.

Claims (10)

1. converter segmented supplies extraction vanadium method, it is characterised in that：Include the following steps：

A, it after vanadium-bearing hot metal enters converter, is blown by oxygen rifle blowing gas, oxygen lance position is invariable when blowing；

B, converting process is divided into three phases, and to the 2.5~3.0min that blows for the first stage since blowing, the first stage uses Oxygen blows；

C, the first stage terminates, and continues 2.0~3.0min of blowing, this process is second stage, and second stage is carried out using nitrogen Blowing；

D, second stage terminates, and continues 2.0~2.5min of blowing, this process is the phase III, and the phase III is carried out using oxygen Blowing；

E, the phase III terminates, and obtains vanadium slag and half steel.

2. converter segmented according to claim 1 supplies extraction vanadium method, it is characterised in that：In step a, the oxygen rifle rifle Position is 1.7~2.0m.

3. converter segmented according to claim 1 supplies extraction vanadium method, it is characterised in that：In step b, in the first stage The pressure of the oxygen is 0.70~0.85MPa, and air supply intensity is 3.2~4.0m³/ (mint vanadium-bearing hot metals).

4. supplying extraction vanadium method according to claims 1 to 3 any one of them converter segmented, it is characterised in that：In step b, Coolant terminate in the first stage before 0.5~1.0min when be added.

5. converter segmented according to claim 4 supplies extraction vanadium method, it is characterised in that：In step b, the coolant Dosage be no more than 20kg/t vanadium-bearing hot metals.

6. converter segmented according to claim 4 or 5 supplies extraction vanadium method, it is characterised in that：It is described cold in step b But agent is the low-phosphorous material of the low-sulfur containing iron and ferriferous oxide, TFe in ingredient>50%；Preferably, the coolant is the pig iron At least one of block, iron scale or ore.

7. converter segmented according to claim 1 supplies extraction vanadium method, it is characterised in that：In step c, in second stage The pressure of the nitrogen is 0.75~0.90MPa, and air supply intensity is 2.5~3.5m³/ (mint vanadium-bearing hot metals).

8. converter segmented according to claim 1 supplies extraction vanadium method, it is characterised in that：In step d, in the phase III The pressure of the oxygen is 0.70~0.85MPa, and air supply intensity is 3.2~4.0m³/ (mint vanadium-bearing hot metals).

9. supplying extraction vanadium method according to claim 1~8 any one of them converter segmented, it is characterised in that：The converter For top-bottom blowing vanadium extracting converter or top blown oxygen converter.

10. converter segmented according to claim 9 supplies extraction vanadium method, it is characterised in that：When converter is top and bottom complex blowing It is 0.001~0.003m that bottom blown gas air supply intensity is controlled when converter extracting vanadium, during non-blowing³/ (mint vanadium-bearing hot metals), blows It is 0.35~0.65m that bottom blown gas air supply intensity is controlled during refining³/ (mint vanadium-bearing hot metals)；The bottom blown gas is all nitrogen Gas.