The present invention primarily relates to a method for isolating lignin, preferably unmodified lignin, from a mixture, in particular a pulping slurry, containing lignin, a cellulose solvent, a cellulose precipitant, minerals and optionally (residual) cellulose and/or hemicellulose and/or hydrolyzation products thereof, comprising or consisting of the following steps: i) removing the cellulose precipitant from the mixture, ii) contacting the mixture with a lignin precipitant, preferably at a temperature below 50° C., to obtain a precipitate, iii) removing the precipitate obtained in step ii) from the mixture, iv) optionally washing the precipitate with a lignin precipitant, v) removing the lignin precipitant from the precipitate, vi) optionally separating the cellulose solvent and the lignin precipitant from the remaining mixture obtained in step iii) with the proviso that in case the cellulose precipitant is the same as the lignin precipitant used in step ii) or contains one or more components of the mixture used as lignin precipitant in step ii), step i) is optional only.