Method for measuring thickness of slag floating on surface of molten metal

Abstract

The primary purpose of this invention is to provide a method whereby the thickness of slag can be measured with a high degree of precision without depending on the operator. This invention uses a microwave distance meter that uses an antenna to emit and receive frequency-modulated microwaves that have a central frequency between 24 and 32 GHz and a frequency-modulation amplitude between 8 and 10 GHz. A first length of time from when the microwave distance meter emits the aforementioned microwaves to when microwaves reflected off the surface of a molten metal are received is computed, as is a second length of time from when the microwaves are emitted to when microwaves reflected off the surface of slag are received. A calculated value c(t1-t2) / 2 is computed from the first length of time t1, the second length of time t2, and the speed c of microwaves in air. A correction formula is obtained in advance from calculated-value measurement results from slag of previously-known thicknesses, and during operation, values obtained by using said correction formula to correct calculated values measured successively by the microwave distance meter are used as slag thicknesses.

Description

technical field [0001] The present invention relates to a method for measuring the thickness of slag suspended on the liquid surface of molten metal, and in particular to a slag thickness capable of continuously measuring the thickness of slag with high precision even when the thickness of the slag is thin test methods. Background technique [0002] In continuous casting of steel, molten steel is poured into a water-cooled mold and brought into contact with the mold to cool the molten steel, thereby forming a solidified shell while continuously drawing the solidified shell downward from the mold to produce a cast strand. [0003] In such continuous casting, a tundish is used as an intermediate container between a mold and a ladle for supplying molten steel to temporarily store molten steel when changing a ladle or to distribute molten steel to a plurality of molds. [0004] At the end of the operation of supplying the molten steel in the ladle to the tundish, a small amount...

AI Technical Summary

Problems solved by technology

[0010] However, the method proposed in Patent Document 1 cannot measure the amount of slag in the tundish.

Therefore, when this method is applied to the supply of molten steel from the ladle to the tundish, there is a problem that when the closing operation of the sliding nozzle is carried out early in the continuous casting operation from the viewpoint of reliably preventing the molten slag from flowing out of the ladle , the residual molten steel in the ladle increases, and the yield of molten steel is greatly reduced

However, the measurement of the slag thickness using the measuring stick is a temporary measurement based on the operator's manual work, so there are problems in that there is a workload, the difference between the measured values ​​​​of each operator is large, and continuous and stable measurement cannot be performed. to measure

[0013] And, also there is the following problem when the gauge rod is packed into molten steel: a part of the lid on the tundish upper surface must be opened, and the inert gas (such as Ar gas) environment in the tundish does not sufficiently block the atmosphere. The secondary oxidation caused by atmospheric intrusion leads to the generation of inclusions in the molten steel, which reduces the internal quality of the slab

The thickness of the slag flowing from the converter into the ladle is also measured using a gauge rod loaded by manual work in the same way as the thickness of the slag in the tundish, which becomes a burden on the operator

Images