ALKALINE PULPING OF CEREAL STRAW

This paper presents a new pulping concept for annual nonwood fiber raw materials. The so-called IDE-process is an alkaline solvent pulping p rocess including three consecutive steps. These are the impregnation ( I), depolymerisation (D) and extraction (E) step. In the impregnation step, the raw material is subjected to strong aqueous sodium carbonate solution. The bulk delignification takes place in the depolymerisatio n step where the raw material is ''cooked'' in aqueous ethanol solutio n. In the third step, the degraded lignin is extracted from the pulp w ith fresh ethanol-water solution. Since no sulphur and sodium hydroxid e is used in the process, the recovery is less complicated than the tr aditional alkaline pulping processes. Trials have also shown that the IDE-process is flexible with regard to the raw materials. If the final pulp would be bleached at a different location, a kraft pulp mill nea rby, the IDE-pulp mill should be almost effluent free. Therefore, an I DE-pulp mill can be economically feasible at small scale and be locate d close to the fiber resources.