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: 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.