Abstract: A method for preparing a coal, which is used alone or in combination with at least one other coal, or a caking additive as a raw material for coke production. The method includes, before the coal or caking additive is delivered to a coke plant, adjusting a grain size such that the amount of grains with a grain size of 6 mm or more in the coal or caking additive satisfies at least one of a degree of entanglement (a - b)/a of 0.20 or more and a portion having a height a of 30 mm or more is 30% or less by mass. The height a is a height of semicoke adhering to a stirrer, the semicoke formed by heating the coal or caking additive in a container while rotating the stirrer, and the height b is a height of the semicoke on an inner wall of the container.

Abstract: A method for evaluating the thermoplasticity of a coal or a caking additive with an apparatus including a container for coal and a stirrer located in the container. The method includes estimating a permeation distance of the coal or caking additive from a value indicating a shape of semicoke formed by rotating the stirrer while heating the coal or caking additive and from a correlation between the value indicating the shape of the semicoke and the permeation distance of the coal or caking additive.

Abstract: A method of producing a coal blend by blending plural brands of coal to produce a coal blend includes letting a surface tension of coal when inert material is assumed to be 100 vol % be ?100, and letting a surface tension of coal when reactive material is assumed to be 100 vol % be ?0, determining ?0 of coal; among brands of coal 1, 2, . . . i, . . . , and n to be blended in a coal blend, specifying coal i in which ?100 is outside of ?0; measuring TI of coal i; and determining a blending ratio of coal i such that w calculated by formula (1) is 20.4 mass % or less w=?(xi×TIi)??(1).

Abstract: A method of estimating a surface tension of coal includes subjecting a surface tension, a physical property value representing a coal rank, and a total inert content of each of different brands of coal to multiple regression analysis to determine in advance a regression equation including the surface tension of coal as an objective variable and the physical property value and the total inert content as explanatory variables; and measuring the physical property value and the total inert content of a coal of which the surface tension is to be estimated, and calculating the surface tension of the coal with the measured physical property value and the measured total inert content, and the regression equation.

Abstract: A method of estimating a surface tension of coal inert material includes determining in advance a first relational expression representing a relationship between a surface tension of coal inert material and a physical property value representing a coal rank; and measuring the physical property value representing the coal rank of a coal for which the surface tension of coal inert material is to be estimated, and calculating the surface tension of the coal inert material by using the measured physical property value representing the coal rank and the first relational expression.

Abstract: Methods for evaluating whether there is a probability that coal will reduce the strength of coke using an apparatus including a stirrer. A degree of entanglement (a?b)/a represented by the heights a and b, or the height a only, is used as an evaluation index for coal, where a height of the semicoke on an inner wall of the container is represented by b, and a height of the semicoke on the stirrer is represented by a. Semicoke formed from heated coal is formed in the container using the degree of entanglement as an evaluation index.

Abstract: A method of evaluating coal includes preparing coal samples having different inert amounts by pulverizing one brand of coal; measuring the inert amounts of the respective coal samples and measuring surface tensions of semi-coke obtained by heat treating the respective coal samples; and determining a regression line based on the inert amounts and the surface tensions and evaluating the coal by using, as an index, a ratio of a variation in the surface tensions to a variation in the inert amounts as determined from the regression line.