Paper is made from wood pulp which is extracted from cellulosic materials like wood, bamboo or other similar material. Approximately 85% of paper made is by the Kraft or Sulphate process which is schematically presented in Figure 11.1. Kraft is the Swedish and German word for ‘strong’. Sulphate process was so called as it produces long fibres which are strong, helping to make tough paper. This process was patented in 1884 and has not been economically viable without a BL recovery boiler. This is an alkaline process which is different from the acidic Sulphite process of making pulp.