Production of cardboard from waste rice husk
http://www.sciencedirect.com/science/article/pii/S2213343714002498 2/7 • • • • • • •
Sale of agriculturalresidue provides further revenue to farmers who have little other opportunities for outside income. Employment is provided to rural labour.
Agriculturalresidues like rice husk and bagasse are locally available either for free or at a very small cost. The major cost in such cases is incurred on collecting and transporting these raw materials. Due to the bulk of these raw materials, transportation can as well be a major cost factor in processing. Nearly all of these raw materials are collected manually and as such the labour costs constitute a big percentage of the total raw material costs. Thus, in countries with very low labour rates, pulp production with these raw materials can be extremely encouraging relative to wood pulping [4]. Consequently, the possibility of manufacturing cardboard from rice husk residues together with bagasse and waste paper was investigated. Their strengths were compared to that of virgin fibres normally used in the production of cardboard for packaging, to see whether the cardboard obtained from rice hulls residues could replace to some extent the pulping material in normal cardboard production. For that purpose, it was important to determine the optimum pulping time in terms of yield, kappa number and lignin content various mixtures of various mixtures of waste papers and rice husk pulp and bagasse pulp and rice husk pulp and to compare the mechanical properties of cardboards manufactured from these mixtures. The optimal amount of virgin fibre to be added also had to be determined so as to maintain strength.
Fibre morphology in nonwood plants used in cardboard making Morphological characteristics, such as fibre length and width, are essential in estimating pulp quality of fibres [5]. Kiaie et al. [6] stated that the flexibility coefficient of bagasse and rice residues is included in high rigid fibres group and thick wall fibre group. Consequently, they do not have efficient elasticity and they are used more on fibre plate, rigid cardboard and cardboard production [7]. Kiaie et al. [6] also concluded the following as shown in Table 1.
Table 1. Biometric properties, chemical composition and morphology characteristics of bagasse and rice.
Biometric properties Chemical composition Morphology characteristics Fibre length: bagasse > rice (lowest) Lignin: (highest) rice > bagasse Slenderness ratio: bagasse > rice Fibre diameter: bagasse (highest) > rice Cellulose: bagasse > rice Flexibility ratio: bagasse > rice Cell wall thickness: bagasse > rice (lowest) Extractive: bagasse > rice Runkel ratio: bagasse > rice Lumen width: bagasse > rice Ash: (highest) rice > bagasse – Source: [6].
Benefits of using rice husk include: Use of local fibre sources would offer import substitution. Rice husk are underutilized. It will expand the economic viability of the existing paper mills and lead to their revival. Saving in foreign exchange will be attained by reducing the amount of imported pulp and exportation of papers and paper products to other countries. Environmental problems on agricultural crop residues would be tackled