a temperature of for example 120 deg f to 300 deg f or 200 deg f to 230 deg f these stage s 24 may maintain the chips under pressures of 60 pounds per square inch psig to 110 psig for a period of 5 to 120 minutes or 20 minutes to 40 minutes at 5 to 45 or even 10 to 30 consistency of pulp to liquor the fiberized chips 17 may have a shives content of 35 to 45 after treatment with oxygen o 2 26 in the delignification stage s 22 the ph level in each of the delignification stages 24 may be alkaline ph the target ph of the chips being discharged from the delignification stages may be in a range of 7 ph to 12 ph or 8 ph to 10 ph downstream of the delignification stages 22 the oxygen delignified pulp which may have a shives content of 35 to 45 is washed 28 and refined 30 before entering a paper machine 32 that forms the pulp into corrugated paper or other corrugated medium preliminary results have been obtained using the pulping process described above these results are shown in the table of fig2 the results indicate a significant improvement in pulp quality using the novel sc pulping process described above major physical pulp properties such as ring crush cmt mullen tensile and tear strength were improved by 25 to 40 as compared to standard one stage carbonate pulp for final pulp yields of 75 to 80 there is a strong correlation between pulp quality improvement and the final yield as well as pulp consistency and degree of pulp washing prior oxygen.