Pulp mill biorefining is still a relatively young area in modern pulping R&D driven by megatrends such as increased costs for fossil oil and wood, but also increased competition on the pulp market. The need for new revenues is obvious if the pulp and paper industry is to maintain its strong position. Biorefining can simplified be defined as the efforts to reach as complete utilization of wood raw material as possible in a pulp mill to reach as high revenues as possible. A pulp mill producing chemical pulp is for several reasons an excellent an industrial platform for biorefining. The chemical pulp mill is able to produce relatively pure cellulose, hemicellulose and lignin. The focus in this paper is on separation of lignin from different types of black liquors, the behavior of these black liquors when they are treated according to the LignoBoost concept which we in this paper refer to as "The lignin separation process". Some properties of the separated lignin will also be briefly discussed. "The lignin separation process" is used to remove lignin from kraft/soda black liquors and it has been developed in cooperation between Innventia and Chalmers University of Technology. The technology was sold to Metso Power 2008 and it is now commercially available. Lignin separation, purification, modification and applications have a high priority in R&D work at our company.