Abstract
This chapter covers relative topics on wheat straw applied as fibrous raw materials for pulping and papermaking industry, i.e., chemical components and anatomy of wheat straw, pulping process and pulping properties, paper and paperboard products from wheat straw pulps, as well as environmental protection issues. Wheat straw is a kind of annual vascular-bundled herbal arthrophyte containing cellulose fibers that are acceptable for pulping and papermaking. The chemical components and anatomy of wheat straw were discussed; practically, soda or soda-AQ chemical pulping processes are common techniques often applied for chemical pulping from wheat straw, conventional and advanced bleaching sequences were introduced, and especially ECF and TCF bleaching techniques have been successfully applied in China’s paper mills. Cooking and black liquor extraction equipment and facilities are explained; chemi-mechanical pulping properties of wheat straw, corrugated medium, and linerboard products from wheat straw CMP pulps are evaluated; and chemical recovery from chemical cooking black liquor and effluent treatment processes are discussed. In this chapter, not only laboratory research results but also some commercial operation experiences are shared. These information and knowledge described in this chapter will help readers to have a good understanding about wheat straw pulping and papermaking; they are useful for pulping and papermaking engineer as reference for design and operation management of wheat straw pulping lines.
Highlights
Chemical pulping and pulp bleachingSoda and soda-anthraquinone (AQ) cooking, as sulfur-free processes, are more suitable in producing pulp fibers from some no-woody raw materials [12]
This chapter covers relative topics on wheat straw applied as fibrous raw materials for pulping and papermaking industry, i.e., chemical components and anatomy of wheat straw, pulping process and pulping properties, paper and paperboard products from wheat straw pulps, as well as environmental protection issues
By this bleaching sequence, bleached wheat straw pulps (BWSPs) with brightness of more than 80%ISO, pulp viscosity of 653 ml/g and breaking length of more than 7000 m (Tables 5 and 6) and less amount bleaching effluent generated about 30 m3/t pulps, decreased by more than 60% of a traditional CEH bleaching process for wheat straw pulps [15]
Summary
Soda and soda-anthraquinone (AQ) cooking, as sulfur-free processes, are more suitable in producing pulp fibers from some no-woody raw materials [12]. The first installation of continuous cooking system with an annual capacity of 100,000 metric tons of wheat straw pulps was operated at Quanlin Paper Group, Shandong, China This successful practice scales up an individual pulp production line capacity from non-wood materials in the world and improves significantly technical specifications of wheat straw pulping. The first midconsistency and shortened TCF bleaching sequence in the world, namely, OQPo (oxygen delignification—chelating metal ions—peroxide bleaching assisted with oxygen) sequence, was successfully commercially operated with the capacity of 150 t/d by Xianhe Co., Henan, China (Figure 4) in 2008 [15] By this bleaching sequence, bleached wheat straw pulps (BWSPs) with brightness of more than 80%ISO, pulp viscosity of 653 ml/g and breaking length of more than 7000 m (Tables 5 and 6) and less amount bleaching effluent generated about 30 m3/t pulps, decreased by more than 60% of a traditional CEH bleaching process for wheat straw pulps [15]. Wheat straw pulps Screened brown pulp Pulp after oxygen stage Pulp after Po stage
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