Pulping/Bleaching

Wood chips are converted into wood pulp using either a chemical (kraft pulp) or a mechanical (mechanical pulp) process. Kraft pulp can be produced using either a Sulfate or a Sulfite process. Under each method, wood chips are “cooked” in a digester under extreme pressure, with a liquor chemical. During this process, the actual fibers are separated from lignin and other impurities to produce wood pulp. The chemical process is the most widely used method for pulp production. Under the mechanical process, the wood chips are physically beaten thereby releasing the fibres. Because there is no need to have a recovery system for chemicals these manufacturing processes are simpler than those used to produce chemical pulp. However, some mechanical processes do introduce chemicals into the production cycle.