The invention provides a
straw cutting-free method for preparing
straw pulp by spherical digester alkali
digestion. The method comprises the following steps of: washing a
straw raw material; adding a hot alkali solution, adding water, mixing uniformly, and heating; performing
digestion by adopting a conventional
sulfate method or a caustic soda
anthraquinone method; stopping the
digestion when the
lignin discharged from the straw
raw material by the digestion reaches 75 to 90 percent, discharging a
black liquor I, and thus obtaining straw pulp; and adding the hot alkali solution into the straw pulp, performing digestion and conventional washing and thus obtaining unbleached pulp, wherein the thin
black liquor discharged during washing is a
black liquor II, the black liquor II and water are added into the new straw
raw material together, and the unbleached pulp is continuously obtained by repeating. The straw
cutting process is eliminated in the method, so that the flow for preparing the pulp by using the straw is simplified; and on the premise of ensuring the digestion effect, the concentration of the
solid matter of the black liquor can be improved to over 13 percent, the stock loss of the raw material is reduced by about 5 percent, the single-pot digestion capacity is improved by 10 to 15 percent, and the yield and the
viscosity of the formed pulp are raised with different degrees.