PROBLEM TO BE SOLVED: To provide a method of preparing a humectant comprising a rice hull carbon comprising adding water and a binder into the rice hull carbon and kneading them, and shaping the mixture through an extruder to macaronis (pipes) to give an air layer inside for improving a moisture retention effect during an iron manufacturing. SOLUTION: A rice hull carbon kneaded with water and a binder (an adhesive) is charged into a hopper 1, fed through a straight screw 3, shaped into macaronis (pipes) using a die 4 and cut using a cutter to have uniform length so that a macaroni-like humectant comprising the rice hull carbon and having an air layer inside is prepared.
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