:. Home

:. Introduction

:. History

:. Producing paper today

:. Latest Technologies

:. Recycling Paper

:. The full paper making process

:. FAQs

:. Glossary

:. References

:. Fun-Crossword


  Making Pulp from Wood

Chemical Pulp

Most chemical woodpulp is made by the sulphate process. Chips from de-barked logs are dissolved in caustic soda and sulphur by heat and pressure leaving a strong brown pulp, coloured by the effect of the chemicals on the lignin and wood sap. The pulp is commonly known as kraft - the German word for strong. About 20% of chemical pulp is made by the sulphite process. Chemical pulping uses less energy than mechanical pulping. In modern mills, recovery boiler operations and the controlled burning of bark and other residues make the chemical pulp mill a net energy producer which can often supply power to the grid, or steam to local domestic heating plants.

Chemical pulp, however, produces a strong liquid effluent that needs to be treated. The term "woodfree" is often used in the trade to signify that the chemical pulping process has been used. it is not meant to be misleading and has been used for decades to mean "free from mechanical wood" (or "ground wood free").


© 2003 design by Ahmed Abdel-Rahman