The Kraft process is the primary chemical method for pulping wood into fibers that can be used to make paper. It uses a hot solution of sodium hydroxide and sodium sulfide, known as white liquor, to break down the lignin in wood while preserving the cellulose fibers. Wood chips are cooked in the white liquor in a pressurized digester. This removes the lignin and yields a black liquor containing dissolved lignin and chemicals. The resulting pulp is then separated and processed further into paper. The black liquor is also processed to recover the chemicals and produce new white liquor in a continuous chemical recovery process.

4. Paper Making Process

5. Source: http://www.epa.gov/ttn/chief/ap42/ch10/final/c10s02.pdf

13. Questions?