PROCESS FOR THE SIMULTANEOUS EXTRACTION OF LIGNIN and SILICA， A MIXTURE OF LIGNIN and SILICA， THE USE OF A MIXTURE OF LIGNIN and SILICA and ELASTOMER

The invention relates to a process for the simultaneous extraction of lignin and silica from lignocellulosic plant material， characterized in that it comprises the steps of: a) fractionating the lignocellulosic plant material in the presence of an acid solution， so as to obtain a solid fraction comprising cellulose， residual lignin and silica; b) extracting simultaneously lignin and silica from the solid fraction obtained in step a) with a basic solution， at a pH between 10 and 13 and at a temperature between 70°C and 90°C， so as to obtain a liquid phase comprising lignin and silica， and a solid phase; c) separating the liquid phase and of the solid phase obtained in step b)， d) coprecipitating a mixture of lignin and silica comprised in the liquid phase， at a pH between 5 and 6. The invention relates to a process for the simultaneous extraction of lignin and silica from lignocellulosic plant material， characterized in that it comprises the steps of: a) fractionating the lignocellulosic plant material in the presence of an acid solution， so as to obtain a solid fraction comprising cellulose， residual lignin and silica; b) extracting simultaneously lignin and silica from the solid fraction obtained in step a) with a basic solution， at a pH between 10 and 13 and at a temperature between 70°C and 90°C， so as to obtain a liquid phase comprising lignin and silica， and a solid phase; c) separating the liquid phase and of the solid phase obtained in step b)， d) coprecipitating a mixture of lignin and silica comprised in the liquid phase， at a pH between 5 and 6.