JPS62107009A - Method for desiliconizing molten pig iron - Google Patents

Abstract

PURPOSE:To considerably improve the work efficiency and productivity of desiliconization by measuring the concn. of silicon in molten pig iron by thermal electromotive force and by regulating conditions during the desiliconization of the molten pig iron in accordance with the measured value. CONSTITUTION:A probe for measuring the amount of silicon is immersed in molten pig iron during desiliconization to measure the concn. of silicon in the molten pig iron. When the concn. of silicon is a point B at a point A of time, the desired final concn. of silicon is obtd. at a point B' by continuing scheduled operation. When the concn. of silicon is a point C, desiliconization is proceeding ahead of the schedule, so a desiliconization curve connecting a starting point S and the point C is drawn to set a point C' and the desired final concn. of silicon is obtd. by finishing desiliconization at the point C'.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for desiliconizing hot metal.

Conventional technology 9Wi construction, 20 (19B?), No. 2.75,
Japanese Patent Publication No. 52-13394 discloses a method in which a special sample is first taken from hot metal, and the sample is cooled and polished before being subjected to a measuring device.

Problems to be Solved by the Invention The conventional method described above takes 5 to 7 minutes, and in order to obtain a more healthy sample, it is necessary to
In the process of applying strong agitation to the hot metal, it is necessary to temporarily stop the process and wait for the hot metal to settle down before sampling, and the total time required for this process reaches 10-15 minutes. For this reason, a decline in work efficiency and productivity was unavoidable.

Means for Solving the Problems The present invention measures the silicon concentration of hot metal by thermoelectromotive force method when desiliconizing hot metal, and adjusts the hot metal desiliconization conditions during the desiliconization process according to the measured value. This is a method for desiliconizing hot metal.

Function The present invention is cast and forged, 20 (19B?), No. 2.7
An immersion type probe as shown in Fig. 3, which incorporates a sensor that utilizes the relationship between silicon concentration and thermoelectromotive force as shown in Fig. 5, is inserted into the hot metal during the desiliconization process without interrupting the desiliconization process. Since it is immersed, it is possible to accurately measure the silicon concentration of the hot metal at that point in time, and thereby change the preset desiliconizing agent use i and, if necessary, the desiliconizing agent supply rate, blowing depth, etc. However, the end point silicon concentration at point 9 can be obtained.

In particular, when gaseous oxygen is used as a desiliconizing agent, the end point hot metal concentration can be controlled by changing the bottle used and the supply rate of gaseous oxygen.

Embodiment FIG. 1 shows the transition of silicon concentration in an embodiment of the present invention. The silicon concentration in the hot metal at the time indicated by A in FIG.
As shown in the figure, when the concentration reached point B, the target end point silicon concentration could be obtained at point B' by continuing the operation as originally planned. On the other hand, when the point C is reached, the desiliconization has progressed more than planned, so the desiliconization curve connecting the starting point S and C is redrawn, a new point C' is predicted, and the process is carried out at the point C'. By completing the process, the target end point silicon concentration can be obtained.

Also, when the point D is reached, the desiliconization is delayed compared to the schedule, so the desiliconization curve connecting the starting point S and D is redrawn and a new D'
By predicting the point and extending the desiliconization treatment until the point D', it was possible to obtain the target end point silicon concentration.

Next, FIG. 2 shows the distribution of end point silicon concentration when desiliconization was performed using a pig iron mixer with a capacity of 800 TON. The crests indicate the conventional process based on the present invention (without control), and the shaded areas indicate the case with the control of the present invention.

In the conventional process, the variation σ was 0.021%, but in the example of the present invention, the variation was reduced by half to 0.010%.

Effects of the Invention The present invention measures the silicon concentration of the molten iron by a thermoelectromotive force method during the desiliconization treatment of hot metal, and adjusts the desiliconization conditions of the hot metal during the desiliconization treatment based on the measured value.

Not only the amount of silicon in the hot metal but also the temperature of the hot metal can be made to reach the target value at the same time as the desiliconization process is completed, and the workability and productivity of the desiliconization process of the hot metal are significantly improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the transition of silicon concentration during desiliconization treatment in an embodiment of the present invention, and a silicon control method based on the actual silicon Iga oil constant value. Figure 3 is a cross-sectional view of the probe for measuring the amount of silicon in hot metal used in the present invention. Probe for silicon content measurement, No. 2, exterior tube, 3, void forming member, 4, e-cement, 5,...
・Cooler 113), 6--・Opening, No. 7...Inflow pipe, 8
・φ・Vacancy, 9...Low temperature side electrode, 10...High temperature side electrode, 11...φ cap, 12 Working...Base, 13...-
,connector.

Claims (1)

[Claims] A method for desiliconizing hot metal, characterized in that when desiliconizing hot metal, the silicon concentration of the hot metal is measured by a thermoelectromotive force method, and the desiliconization conditions of the hot metal during the desiliconization treatment are adjusted according to the measured value. .