A method for delignifying

The invention relates to a process for delignifying lignocellulosic raw materials, through the use of sulfites in the presence of an alkaline component, in particular sodium hydroxide or sodium carbonate or a mixture thereof, in aqueous solution under application of elevated temperature and elevated pressure, characterized in that at the beginning of expansion, the used aqueous sulfite solution, and the temperature is increased up to the maximum reaction temperature is increased, wherein the alkaline component is added only after the start of the pulping process.