PROBLEM TO BE SOLVED: To provide a method for processing draff which is hardly digested favorably as it is to be easily digested. SOLUTION: Draff is heated at a temperature about not to be red in viewing with eyes and heat-carbonized to a temperature at which gas recognizable with eyes does not generate by using, e.g. a carbonization device of the figure, then the resultant carbonized material is finely crushed and dipped in an acidic aqueous solution to elute materials contained in the carbonized material into the acidic aqueous solution.
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