OXYGEN PULPING OF HARDWOODS AND SOFTWOODS UNDER OXYGEN-RICH CONDITIONS.

In the reported experiments, red maple and loblolly pine were pulped at low consistency with air and alkali at 2550 psi (17,600 kPa). The pulps were then compared with high-consistency oxygen pulps and with kraft pulps. Red maple chips gave a 65%-yield pulp with the low-consistency system that compared favorably in strength properties to a 50%-yield kraft pulp and was substantially better than a high-consistency oxygen pulp using fiberized wood. The low-consistency system also gave superior results with loblolly pine, but the strength properties still did not match those of the kraft reference pulps. The results demonstrate the advantage of pulping under conditions of high oxygen availability.