Method of detecting slag in molten steel flow

A method of detecting slag in a molten steel flow, comprising:

• an image capturing step of sequentially capturing a molten steel flow which is directed from a converter toward a ladle and includes molten steel and slag to acquire a plurality of captured images of the molten steel flow;
• a histogram creation step of creating a histogram, in which a density parameter corresponding to a density of each pixel constituting each captured image is shown on a horizontal axis and the number of pixels that is a total number of pixels each having the density parameter is shown on a vertical axis, for each captured image;
• a maximum peak point detection step of detecting a maximum peak point, in which the number of pixels is an absolute maximum value, for each histogram;
• and
• a maximum peak point type determination step of determining to which of the slag or the molten steel the maximum peak point of each histogram corresponds,
• wherein when a maximum peak point Pn of a histogram of an nth (n≥2) captured image is determined in the maximum peak point type determination step,
• in a case where a variation ΔT of a density parameter Tn at the maximum peak point Pn with respect to a density parameter Tn-1 at a maximum peak point Pn-1 in a histogram of an n−1th captured image is equal to or more than a predetermined value, it is determined that the maximum peak point Pn corresponds to the slag, and
• in a case where a variation ΔT is less than the predetermined value, if a variation ΔT′ of the density parameter Tn with respect to a density parameter Tj at a maximum peak point Pj in a histogram of a jth (j≤n−1) captured image, in which a maximum peak point is determined as the molten steel, is equal to or more than the predetermined value, it is determined that the maximum peak point Pn corresponds to the slag, and if a variation ΔT′ is less than the predetermined value, it is determined that the maximum peak point Pn corresponds to the molten steel.