To provide a method by which high-pressure steam generated during mechanical refining flows back through one or a plurality of refining zone(s) in plates and is extracted as high pressure steam.

A refining plate for refining lignocellulosic material includes: a radially outer peripheral edge 38 and a substrate surface; a refining zone 14 having a plurality of substantially radially disposed bars 18 and grooves between the bars, wherein the bars protrude upward from the substrate surface and the grooves each have a groove width, and a steam channel 34 traversing the bars and grooves of the refining zone, wherein the steam channel 34 has a radially outer end radially inward of the outer peripheral edge of the plate and the steam channel has a width substantially greater than the groove width.