Abstract: Medium consistency oxygen delignification of pulp is carried out in a series of tubular reaction zones. Rapid delignification is achieved by agitating the pulp by rotating a timing screw in the first reaction zone at a speed in excess of 10 rpm, modifying the flights on the timing screw to increase the amount of agitation, or a combination of the two. Primary oxygenation is carried out in the first reaction zone while subsequent zones provide the retention time needed for the delignification reaction to go to completion. A thick stock pump is used to introduce the pulp into the first reaction zone.

Abstract: Thermal insulating material of cellulosic fibers is prepared by treating wood chips or other fibrous cellulosic material with saturated steam at elevated temperatures and pressures and then fiberizing the treated material. A fire-retardant chemical is added to the material immediately prior to fiberization. The resulting fiberized cellulosic material when dried exhibits superior flame and fire resistance properties.