Utilization of kraft pulp production residues in clay brick production

The main objective of this study is to investigate the utilization potential of kraft pulp production residues in clay brick. Kraft pulp production is the primary phase of the paper industry. Long cellulose fibers are produced from wood, straw and reeds in kraft pulp production. Short cellulose fibers are separated as an organic waste material from the production system. This type of residue is only utilized in agricultural purpose or in the production of moulded egg cartons. Kraft pulp production plant of Seka Company (located at Afyon-Çay/Turkey), which has 50,000 tpy dried pulp production capacity, generates important amount of organic wastes. Location of the plant is very close to brick manufacturing facilities and this is the main encouraging reason for the investigation study. One way of the increasing the insulation capacity of the brick is generating porosity in clay body. Combustible organic types of pore forming additives are most frequently used for this purpose. Due to the organic nature of pulp residue, pore-forming ability in clay body was investigated. For this purpose, increasing amount of residue (0%, 2.5%, 5% and 10 wt%) was mixed with raw brick-clay. All samples were fired at 900 °C. Effect on shaping, plasticity, density and mechanical properties were investigated. 2.5 to 5% residue additions were found to be effective for the pore forming in clay body with acceptable mechanical properties. It was observed that, fibrous nature of residue does not create any extrusion problem but increase in residue addition increased the water content for the plasticity. As a conclusion, kraft pulp residues can be utilized in brick-clay as an organic pore-forming agent and by this way it can be utilized in environmentally safe way.