TO CLARIFY THE RELATION BETWEEN THE FREQUENCY OF THE GRIT/FIBRE INTERACTION AND THE PRODUCTION RATE AND PULP QUALITY.

THE PRODUCTION OF MECHANICAL PULP BY PRESSURIZED GRINDING OF WOOD (PGW) IS A COMPARATIVELY NEW PROCESS. DATA ON THE EFFECT OF PARAMETERS, SUCH AS GRIT SIZE, SHARPENING PATTERN AND ROTATIONAL SPEED, ARE LACKING TO A GREAT EXTENT WHEN OPTIMISING THE PGW PROCESS.
IN THE FIRST PART OF THE PROJECT, TRIALS WILL BE CARRIED OUT BY COMPARING GRINDING STONES WITH THREE DIFFERENT GRIT DIMENSIONS. IN A PILOT PRESSURIZED GRINDER STONES OF THE SAME COMPOSITION BUT WITH VARYING GRIT SIZES WILL BE TRIMMED, SHARPENED AND STABILIZED STONES UNDER EQUAL CONDITIONS. WITH THE WELL STABILISED STONES PULP WILL BE PRODUCED TO VARIOUS FREENESS LEVELS AND TESTED FOR PULP AND SHEET PROPERTIES.
IN THE SECOND PART OF THE PROJECT, THE SURFACE OF ONE STONE WILL BE TREATED IN AN UNCONVENTIONAL FASHION. AFTER STABILISING THE SURFACE AND OPTIMISING THE GRINDING CONDITIONS OF THE STONE WITH THE UNCONVENTIONAL SHARPENING PATTERN, SEVERAL PRINTING GRADE PULPS WILL BE MADE IN THE PRESSURIZED GRINDING MODE.
PROCESS PARAMETERS AND PULP PROPERTIES WILL BE EVALUATED AND COMPARED TO REFERENCE PWG-PULP.