1 correct gun position control

To some extent, the oxygen lance operation of the double-blown converter steel making is mainly to adjust and control the proper (FeO) content in the slag through the change of the gun position to meet the needs of each stage of the blowing process. If the (FeO) is improperly controlled, it will bring difficulties to the blowing, such as the slag is too late, easy to "back to dry"; or the slag is too early, easy to splash, so the key to controlling the splash is to control the blowing position .

1.1 Adjustment and control of the gun position in the pre-blowing stage

Before opening the blow, the operator should know the following details:

a) the composition of molten iron, mainly the content of silicon, sulfur and phosphorus;

b) molten iron temperature;

c) The condition of the furnace is whether it is a new furnace or an old furnace, whether it is replenished, what is the amount of the furnace, whether there is any residual molten steel and slag in the furnace;

d) the type of steel being blown and its requirements for slagging and temperature control;

e) The operation of the previous or previous furnace, the liquid level of the furnace and the bottom of the furnace.

I must be aware of the above situation. The principle of pre-adjustment and control is to prematurely slag and refine the slag. In the early stage of blowing, the characteristics of silicon and manganese are rapidly oxidized, the concentration of SiO2 in the slag is large, and the temperature of the molten pool is not high. At this time, the lime added to the furnace is required to be formed as soon as possible, so as to form an active slag having an alkalinity of ~1.5 to 1.7. To reduce the erosion of acid slag on the lining, and increase the rate of desulfurization and dephosphorization in the early stage of blowing. To this end, a higher gun position should be used. If the gun position is too low, not only will the low slag (FeO) form a high melting point on the lime surface, but the dense 2CaO•SiO2 will hinder the melting of the lime and will not be able to be slag. Splashes are well covered on the surface of the molten pool. Of course, the previous gun position should not be too high for a long time to avoid serious splashing.

Correctly control the pre-temperature. If the pre-existing temperature is low, a large amount of iron oxide will accumulate in the slag. Then, when the element is oxidized and the molten pool is heated, it will suddenly cause intense oxidation of carbon, which is likely to cause explosive splashing. When the temperature of the furnace is very high, it is possible to add some lime at the same time as the gun is to be thickened, thickening the slag, and sometimes it has some effect on suppressing the splashing, but the amount of addition should not be too much, and if the calcification is added, if it is not continued, Lime should be properly lowered to reduce the enthalpy (FeO) to avoid severe splashing during the intense decarburization after the end of the oxidation of silicomanganese and the increase in bath temperature.

1.2 Blowing mid-term gun position control

The basic principle of gun position control in the blowing process is: continue to slag, slag, rapid decarburization, no splashing, and uniform temperature rise in the molten pool. The middle of the blowing is characterized by strong decarburization. In this stage, not only the oxygen blown in is used for the oxidation of carbon, but also the iron oxide in the slag is consumed in large quantities. The reduction of strontium (FeO) in the slag will make the slag The melting point rises, the fluidity decreases, and the phenomenon of “back-drying” occurs, affecting the removal of sulfur and phosphorus, and even the phenomenon of phosphorus return. The splashing is also serious. In order to prevent the medium-term slag from returning, the gun should be properly raised to make the slag properly ∑ (FeO).

1.3 gun position control in the late stage of blowing

The later task is to further adjust the oxidizing and fluidity of the slag, continue to remove sulfur and phosphorus, make the molten steel composition and temperature uniform, stabilize the flame, and facilitate the accurate control of the end point. The speed of the gun should be slow and should not be too fast. Otherwise, it will cause splashing, smelting low carbon steel, and many adopt carbonation method. Therefore, it is very important to strengthen the molten pool agitation in the later stage to accelerate the decarburization in the later stage, the temperature and composition of the uniform molten pool and the reduction of the strontium (FeO) content of the final slag. . For this reason, when the process slag is not very good, or the medium-term slag is more serious, the slag should be properly raised in the later stage, and when the end point is approached, the gun is appropriately lowered to strengthen the molten pool and the temperature of the molten pool. Homogenizes the composition, reduces the enthalpy (FeO) in the final slag, increases the metal and alloy yield and reduces the erosion of the lining.

3 reasonable furnace type control.

Maintaining a reasonable furnace type is the most effective way to control splashing under existing technology and equipment conditions. For example, proper bottom height and liquid level should be used, and a suitable bottom blowing mode should be adopted according to the smelting steel grade. Higher, it is necessary to take timely measures to deal with the treatment of the bottom of the furnace should take the principle of diligent and light handling.

3.1 It is possible to use a top gun to properly purge after leaving the residue;

3.2 Reduce the frequency of slag splashing and shorten the slag splash time

3.3 Continuous smelting of 3~4 furnace low carbon steel, low carbon and high iron oxide slag tapping.

3.4 Appropriate reduction of slag basicity and magnesium oxide content.

3.5 Do a good job of heat balance, and strive to achieve a slightly richer heat, so as to maintain the end point carbon, and not because the heat is too rich, the amount of cooling material is difficult to control the splash; it is also possible to use the residue retention operation, do not splash the slag when splashing the furnace Dry, leaving about 1/3 of the slag in the furnace, the remaining slag is beneficial to the rapid slag formation in the early stage of blowing, while reducing the amount of coolant added and the degree of foaming of the slag, and shifting the peak of foaming In order to achieve the purpose of controlling the splashing, when the slag is severely foamed, the gun position is raised for a short time, so that the oxygen gun exceeds the molten pool surface of the foam, and the impact of the oxygen jet is used to destroy the foam and reduce the splash.

In addition, prohibiting over-loading, increasing the quasi-loading rate, stabilizing the quality of raw materials, and improving the operating level are also effective means of controlling splashing; especially for small and medium-sized converters.