1. A method of multi-stage, multi-speed rotary desulfurization of molten iron comprising:

the molten iron desulphurization process comprises a plurality of stages with different molten iron rotation speeds.

2. The method of claim 1, wherein the plurality of different molten iron rotational speeds have no more than 5 stages.

3. The method of claim 2, wherein the plurality of stages of different molten iron rotational speeds are 3 stages.

4. The method according to claim 3, wherein the molten iron rotation speed of the first stage of the plurality of stages of different molten iron rotation speeds is 6 to 8 rpm.

5. The method according to claim 3, wherein the molten iron rotation speed of the second stage of the plurality of stages of different molten iron rotation speeds is 8 to 10 rpm.

6. The method according to claim 3, wherein the molten iron rotation speed of a third stage of the plurality of stages with different molten iron rotation speeds is 6 to 8 rpm.

7. The method according to claim 3, wherein the molten iron rotation time of the first stage of the plurality of stages of different molten iron rotation speeds is 200 to 400 seconds.

8. The method according to claim 3, wherein the molten iron rotation time of the second stage of the plurality of stages of different molten iron rotation speeds is 400 to 800 seconds.

9. The method according to claim 3, wherein the molten iron rotation time of the third stage of the plurality of stages with different molten iron rotation speeds is 200 to 400 seconds.

10. The method of claim 1, wherein the method of desulfurizing molten iron comprises a blow desulfurization method or a KR desulfurization method.

Background

Molten iron desulphurization is a common molten iron treatment process technology. The molten iron desulphurization method widely applied in domestic steel mills at present mainly comprises a blowing method and a KR method. The blowing method adopts inert gas as a carrier, and the desulfurization powder is sprayed into molten iron through a spray gun made of refractory materials, and the carrier gas simultaneously plays a role in stirring the molten iron, so that the desulfurizing agent and the molten iron are fully mixed, the diffusion of the desulfurizing agent in the molten iron is accelerated, the desulfurizing agent and the molten iron are fully reacted, and the desulfurization effect is achieved. The method has the main defects of low desulfurization efficiency, low utilization rate of the desulfurizer and large consumption. The KR method was developed and applied in Japan 1995. A cross-shaped stirring head made of refractory materials is immersed into molten iron for a certain depth, and the molten iron is stirred by a stirrer to form a vortex, so that desulfurization powder is fully diffused along with the vortex of the molten iron and fully reacts with the molten iron, and the desulfurization effect is achieved. The method has the main advantages that: the dynamic condition of desulfurization is good, so the desulfurization efficiency is high, the utilization rate of the desulfurizer is high, and the consumption is low; the main disadvantages are: the equipment is complex, one-time investment is large, simultaneously, the occupied area is large, and a plurality of steel mills with narrow and small fields cannot be applied due to small fields, large investment and the like.

The currently widely used molten iron desulfurization method is a blowing desulfurization method in which a desulfurizing agent is sprayed into molten iron mainly by a spray gun immersed in the molten iron; KR method in which desulfurization is carried out by stirring and mixing the desulfurizing agent and molten iron sufficiently in molten iron using a stirring wheel made of refractory material. The KR method has high utilization rate of the desulfurizer and good desulfurization effect, but has large equipment investment and large consumption of maintenance and spare parts; the blowing method has simple equipment and small investment, but has low utilization rate of the desulfurizer and unsatisfactory desulfurization effect. Aiming at the problems of the blowing method, the rotary blowing method is adopted, the utilization rate of the desulfurizer and the desulfurization effect are improved, and the equipment investment is relatively low.

The further development of the blowing desulfurization method is a rotary spray gun blowing desulfurization method, the method uses a motor and a speed reducing mechanism, so that a spray gun rotates at a specified rotating speed, the diffusion of a desulfurizing agent in molten iron is accelerated, compared with a simple blowing desulfurization method, the rotary spray gun blowing desulfurization method has higher desulfurization efficiency and smaller desulfurizing agent consumption, meanwhile, the equipment investment is not increased greatly, and the occupied area is also smaller. The currently used rotary blowing method adopts the set rotating speed for rotary blowing in the blowing process, the rotating speed is constant in the one-furnace iron blowing desulfurization process, the optimal rotating speed is different aiming at different stages of blowing desulfurization, and the optimized rotary blowing effect cannot be realized by the blowing at the single rotating speed.

Disclosure of Invention

In view of the above, the present invention provides a multi-stage multi-speed molten iron rotary desulfurization method, which has a better desulfurization effect.

The invention provides a method for multi-section multi-speed rotary desulfurization of molten iron, which comprises the following steps:

the molten iron desulphurization process comprises a plurality of stages with different molten iron rotation speeds.

Preferably, the plurality of stages with different molten iron rotation speeds are less than or equal to 5 stages.

Preferably, the plurality of stages with different molten iron rotation speeds are 3 stages.

Preferably, the molten iron rotation speed of the first stage of the plurality of stages with different molten iron rotation speeds is 6-8 rpm.

Preferably, the molten iron rotation speed of the second stage of the plurality of stages with different molten iron rotation speeds is 8-10 rpm.

Preferably, the molten iron rotation speed of the third stage of the plurality of stages with different molten iron rotation speeds is 6-8 rpm.

Preferably, the molten iron rotation time in the first stage of the plurality of stages with different molten iron rotation speeds is 200 to 400 seconds.

Preferably, the molten iron rotation time of the second stage of the plurality of stages with different molten iron rotation speeds is 400 to 800 seconds.

Preferably, the molten iron rotation time in the third stage of the plurality of stages with different molten iron rotation speeds is 200 to 400 seconds.

Preferably, the method for desulfurizing molten iron includes a blow desulfurization method or a KR desulfurization method.

The invention adopts multi-section and multi-speed rotary blowing, and realizes better rotary blowing molten iron desulphurization effect by reasonably adjusting the rotary blowing process under the condition of not increasing equipment investment. Although the existing common rotary blowing molten iron desulphurization control technology can set different rotating speeds to control the blowing process, only one constant rotating speed can be set in each furnace molten iron rotary desulphurization blowing process, and the optimization control cannot be carried out aiming at different stages of the molten iron desulphurization blowing process. When the rotating speed of molten iron rotary desulfurization injection is higher, the radial diffusion of the desulfurizer in the molten iron is weak, but the uniformity in the circumferential direction is better, the molten iron splashing is relatively weak, the molten iron scours the gun body strongly, and the service life of the gun body is shorter; when the rotating speed is lower, the desulfurizer is strong in radial diffusion in molten iron, but poor in uniformity in the circumferential direction, but strong in molten iron splashing, small in molten iron scouring on the gun body, and long in service life of the gun body. The multi-section multi-speed rotary desulfurization injection can give consideration to different working conditions and field requirements, and different injection control strategies are formulated, so that the high-efficiency, low-consumption and long-life molten iron desulfurization process system is better met.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other examples, which may be modified or appreciated by those of ordinary skill in the art based on the examples given herein, are intended to be within the scope of the present invention. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. In the examples, the methods used were all conventional methods unless otherwise specified.

The invention provides a method for multi-section multi-speed molten iron rotary blowing desulfurization, which comprises the following steps:

the molten iron desulphurization process comprises a plurality of stages with different molten iron rotation speeds.

In the present invention, the plurality of stages of different molten iron rotation speeds are preferably 5 stages or less, more preferably 4 stages or less, and most preferably 3 stages.

In the invention, the molten iron rotation speed of the first stage of the plurality of stages with different molten iron rotation speeds is preferably 6-8 rpm, more preferably 6-7 rpm, and most preferably 6 rpm; the molten iron rotation time in the first stage of the plurality of stages with different molten iron rotation speeds is preferably 200 to 400 seconds, more preferably 250 to 350 seconds, and most preferably 300 seconds; the acceleration and deceleration strategy of the molten iron rotation in the first stage of the stages with different molten iron rotation speeds is preferably normal acceleration and deceleration, and the acceleration of the normal acceleration and deceleration is preferably 0.8-1.2 revolutions/deviceSecond of²More preferably 1 revolution/second². In the present invention, the acceleration and deceleration strategy includes: the speed is accelerated and decelerated quickly, the required time is short, but the impact on equipment is large, and the molten iron splashing is large; normal acceleration and deceleration, medium acceleration and deceleration speed, long time needed, medium impact on equipment, medium molten iron splashing and the like; the speed is slowly increased and decreased, the speed is slow, the required time is long, the impact on equipment is small, and the molten iron splashing is small. In the invention, the selection of the acceleration and deceleration strategy preferably mainly refers to the time of a speed section, the time is as long as possible, and slow acceleration and deceleration are selected, so that the impact of equipment and molten iron splashing are reduced.

In the invention, the rotating speed of the molten iron in the second stage of the plurality of stages with different rotating speeds of the molten iron is preferably 8-10 rpm, more preferably 8-9 rpm, and most preferably 8 rpm; the molten iron rotation time of the second stage of the plurality of stages with different molten iron rotation speeds is preferably 400 to 800 seconds, more preferably 500 to 700 seconds, and most preferably 600 seconds; the strategy of acceleration and deceleration of molten iron rotation in the second stage of the plurality of stages with different molten iron rotation speeds is preferably slow acceleration and deceleration; the acceleration of the retarding acceleration and deceleration is preferably 0.5-0.8 r/s²More preferably 0.6 to 0.7 rpm/sec²Most preferably 0.6 rpm/sec²。

In the invention, the molten iron rotation speed of the third stage of the multiple stages with different molten iron rotation speeds is preferably 6-8 rpm, more preferably 6-7 rpm, and most preferably 6 rpm; the molten iron rotation time in the third stage of the plurality of stages with different molten iron rotation speeds is preferably 200 to 400 seconds, more preferably 250 to 350 seconds, and most preferably 300 seconds; the acceleration and deceleration method for molten iron rotation in the third stage of the plurality of stages with different molten iron rotation speeds is preferably normal acceleration and deceleration; the acceleration of the normal acceleration and deceleration is preferably 0.8-1.2 revolutions/second²More preferably 1 revolution/second²。

In the present invention, the method of desulfurizing molten iron preferably includes a blow desulfurization method or a KR desulfurization method.

In the present invention, the desulfurizing agent used in the molten iron desulfurization process preferably includes: mg and CaO; the mass content of Mg is preferably 15-25%, more preferably 18-22%, and most preferably 20%; the mass content of CaO is preferably 75 to 85%, more preferably 78 to 82%, and most preferably 80%.

In the present invention, the molten iron desulphurization process preferably includes the following molten iron components:

4-4.5 wt% of C;

0.1 to 0.15 wt% of Si;

0.13-0.17 wt% Mn;

0.05 to 0.09 wt% of P;

0.07 to 0.08 wt% S;

0.2 to 0.4 wt% of V;

0.1 to 0.15 wt% of Ti;

the balance being Fe.

In the invention, the mass content of C is preferably 4.1-4.5%, more preferably 4.2-4.5%, more preferably 4.3-4.5%, more preferably 4.4-4.5%, and most preferably 4.411%; the mass content of Si is preferably 0.11-0.14%, more preferably 0.12-0.13%; the mass content of Mn is preferably 0.14-0.16%, more preferably 0.15%; the mass content of P is preferably 0.06-0.08%, and more preferably 0.07%; the mass content of S is preferably 0.072-0.078%, more preferably 0.074-0.076%, and most preferably 0.075%; the mass content of V is preferably 0.3%; the mass content of Ti is preferably 0.11 to 0.14%, more preferably 0.12 to 0.13%.

In the invention, the temperature of the molten iron before desulfurization is preferably 1275-1285 ℃, more preferably 1278-1282 ℃, and most preferably 1280 ℃; the temperature of the desulfurized molten iron is preferably 1265-1275 ℃, more preferably 1268-1272 ℃, and most preferably 1270 ℃.

In the invention, the addition amount of the desulfurizer can be 0.53-1.55 kg, 0.6-1.5 kg, 0.8-1.2 kg and 1kg of magnesium in each ton of molten iron; the average mass of the magnesium can be 0.9-0.95 kg, can be 0.91-0.94 kg, can be 0.92-0.93 kg; the weight of CaO (lime) in the desulfurizer per ton of molten iron can be 2.24-5.85 kg, can be 2-5 kg, and can be 3-4 kg; the average weight of CaO may be 3.7 to 4.2kg, may be 3.8 to 4.1kg, and may be 3.9 to 4 kg.

In the invention, the adding amount of the desulfurizing agent in the molten iron desulfurization process is added according to the mass content of S in the molten iron, and when 0.001 wt% of S is contained in each ton of molten iron, the mass of magnesium in the desulfurizing agent can be 0.0099-0.0187 kg, can be 0.01-0.016 kg and can be 0.012-0.014 kg; the average mass can be 0.01-0.014 kg, and can be 0.011-0.012 kg; the weight of CaO in the desulfurizer can be 0.026-0.092 kg, 0.03-0.09 kg, 0.04-0.08 kg, 0.05-0.07 kg, and 0.06 kg; the average mass may be 0.05-0.06 kg, and may be 0.055 kg. In the invention, the less the consumption of the desulfurizing agent, the better, but the improvement of the utilization efficiency of the desulfurizing agent is mainly considered by considering the fluctuation of the sulfur content of the molten iron, the different requirements of the next process on the sulfur content of the semisteel (molten iron), and the like.

In the invention, the mass content of S in the desulfurized molten iron is 0.01-0.015 percent, and the average content is 0.011-0.012 percent; the mass content of S in the slag is 3-4%.

In the invention, a complete molten iron desulphurization process of a furnace of molten iron needs a molten iron desulphurization process system, the multi-section multi-speed rotary blowing molten iron desulphurization process system in the invention consists of a plurality of process sections, and each process section comprises 4 parameters of a section number, running time, running speed and an acceleration and deceleration strategy; the section number is the execution sequence of the process system, and the running time is the time of stable running after acceleration and deceleration are finished.

In the invention, a multi-section multi-speed rotary blowing molten iron desulphurization process system at least comprises one process section, the rotary blowing desulphurization process system is the same as the common rotary blowing molten iron desulphurization process system, and the whole desulphurization process is completed by a given rotating speed. In the invention, a multi-section multi-speed rotary blowing molten iron desulphurization process system can contain N process sections at most, the number of N is almost not limited, but too many process sections cause frequent speed change and are not beneficial to the stable operation of rotary blowing molten iron desulphurization, so N is less than or equal to 5 in principle; and controlling the multi-section multi-speed rotary blowing molten iron desulfurization, most typically controlling the three-section three-speed rotary blowing molten iron desulfurization in the front, middle and later stages.

The invention adopts multi-section and multi-speed rotary blowing, and realizes better rotary blowing molten iron desulphurization effect by reasonably adjusting the rotary blowing process under the condition of not increasing equipment investment. Although the existing common rotary blowing molten iron desulphurization control technology can set different rotating speeds to control the blowing process, only one constant rotating speed can be set in each furnace molten iron rotary desulphurization blowing process, and the optimization control cannot be carried out aiming at different stages of the molten iron desulphurization blowing process. When the rotating speed of molten iron rotary desulfurization injection is higher, the desulfurizer is better diffused in all directions of the molten iron, but the molten iron is relatively weaker in splashing, the molten iron is stronger in scouring the gun body, and the service life of the gun body is shorter; when the rotating speed is lower, the desulfurizer is diffused in a single direction, the diffusion effect is weaker, but the molten iron splashing is stronger, but the molten iron scouring on the gun body is smaller, and the service life of the gun body is longer. The multi-section multi-speed rotary desulfurization injection can give consideration to different working conditions and field requirements, and different injection control strategies are formulated, so that the high-efficiency, low-consumption and long-life molten iron desulfurization process system is better met.

The components of the desulfurizing agent used in the following examples of the present invention are: 20 wt% Mg +80 wt% CaO.

Comparative example 1

Desulfurizing the molten iron by adopting a single-speed rotary blowing desulfurization method, wherein the rotating speed of a desulfurization device in the desulfurization process is 9 revolutions per minute, and the desulfurization time is 20 minutes; consumption of a desulfurizing agent: 0.96kg of Mg and 3.84kg of CaO per ton of molten iron; the temperature of the molten iron before desulfurization is 1280 ℃, and the temperature of the molten iron after desulfurization is 1270 ℃.

The molten iron is intercepted by a long paper tube and sampled, the sulfur content in the molten iron is detected by water cooling, and the detection result is as follows: before desulfurization: 0.07 wt% S; the mass content of S in the desulfurized molten iron is 0.012 percent.

And detecting the mass content of S in the desulfurized slag, wherein the detection result shows that the mass content of S in the desulfurized slag is 3.4%.

Example 1

The molten iron is desulfurized by adopting a three-section three-speed rotary blowing desulfurization method, and the desulfurization processThe first stage of the medium-sized desulfurization equipment has the rotating speed of 6 revolutions per minute, the desulfurization time of 5min and the acceleration and deceleration speed of 1.0 revolution per second²(ii) a The rotation speed of the second stage is 8 r/min, the desulfurization time is 8min, and the acceleration and deceleration speed is 1.0 r/s²(ii) a The rotation speed of the third stage is 6 r/min, the desulfurization time is 5min, and the acceleration and deceleration speed is-1.0 r/s²(ii) a Consumption of a desulfurizing agent: 0.95kgMg and 3.8kgCaO per ton of molten iron; the temperature of the molten iron before desulfurization is 1280 ℃, and the temperature of the molten iron after desulfurization is 1270 ℃.

Detecting sulfur in the molten iron before and after desulfurization, wherein the detection result is as follows: before desulfurization: 0.07 wt% S; the mass content of S in the desulfurized molten iron is 0.011 percent.

And detecting the mass content of S in the desulfurized slag, wherein the detection result shows that the mass content of S in the desulfurized slag is 3.6%.

Example 2

The molten iron is desulfurized by adopting a three-section three-speed rotary blowing desulfurization method, the first-stage rotating speed of desulfurization equipment in the desulfurization process is 6 revolutions per minute, the desulfurization time is 5min, and the acceleration and deceleration speed is 1.0 revolution per second²(ii) a The rotation speed of the second stage is 8 r/min, the desulfurization time is 11min, and the acceleration and deceleration speed is 1.0 r/s²(ii) a The rotation speed of the third stage is 6 r/min, the desulfurization time is 5min, and the acceleration and deceleration speed is-1.0 r/s²(ii) a Consumption of a desulfurizing agent: 1.4kg of Mg and 5.6kg of CaO per ton of molten iron; the temperature of the molten iron before desulfurization is 1285 ℃, and the temperature of the molten iron after desulfurization is 1270 ℃.

The sulfur in the molten iron before and after desulfurization is detected, and the detection result is as follows: before desulfurization: 0.10 wt% S; the mass content of S in the desulfurized molten iron is 0.010 percent.

And detecting the mass content of S in the desulfurized slag, wherein the detection result shows that the mass content of S in the desulfurized slag is 3.8%.

The invention adopts multi-section and multi-speed rotary blowing, and realizes better rotary blowing molten iron desulphurization effect by reasonably adjusting the rotary blowing process under the condition of not increasing equipment investment. Although the existing common rotary blowing molten iron desulphurization control technology can set different rotating speeds to control the blowing process, only one constant rotating speed can be set in each furnace molten iron rotary desulphurization blowing process, and the optimization control cannot be carried out aiming at different stages of the molten iron desulphurization blowing process. When the rotating speed of molten iron rotary desulfurization injection is higher, the desulfurizer is better diffused in all directions of the molten iron, but the molten iron is relatively weaker in splashing, the molten iron is stronger in scouring the gun body, and the service life of the gun body is shorter; when the rotating speed is lower, the desulfurizer is diffused in a single direction, the diffusion effect is weaker, but the molten iron splashing is stronger, but the molten iron scouring on the gun body is smaller, and the service life of the gun body is longer. The multi-section multi-speed rotary desulfurization injection can give consideration to different working conditions and field requirements, and different injection control strategies are formulated, so that the high-efficiency, low-consumption and long-life molten iron desulfurization process system is better met.

While only the preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.