Abstract: Methods and apparatus are disclosed for refining lignocellulosic material between a pair of relatively rotary refining elements forming an annular outer refining zone and a central feed zone. The method includes feeding the lignocellulosic material to the central feed zone, accelerating the lignocellulosic material through the central feed zone towards the annular outer refining zone without lignocellulosic material build up in the central feed zone and substantially without working the lignocellulosic material in the central feed zone, the density of the lignocellulosic material in the central feed zone being a maximum of about 10 kg/m3, and mechanically working the lignocellulosic material in the annular outer refining zone, and in which the relatively rotary refining elements have a relative speed of greater than about 50 m/sec.

Abstract: Refining apparatus is disclosed including a pair of relatively rotatable refining disks including radial refining bars extending along at least part of the refining gap between those disks, and at least one of the refining bars comprising a sensor bar including strain gauges for sensing the load exerted thereon during refining at a number of points along the sensor bar.