Recovered Paper, Recycled Fibers

1 Role of Recovered Paper In the Paper and Board Industry 

In the past chemical pulp was the most important raw material for paper production, but now this has been replaced by recovered paper. 158 million tons of this raw material were used globally in 2002. This volume exceeds the total volume of woodpulp, i.e. chemical pulp (117 million tons) and mechanical pulp (36 million tons) [1]. These figures show that recycled fibers play a very important role today in the global paper industry as a substitute for virgin fiber pulps. 

Recovered paper ullllzatfon and paper production, 10 tons 

USA Japan China Germany South Korea France Italy Canada Indonesia United Kingdom Spain Taiwan 

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Refining and Fractionation. These processes are used to alter and select cellulose properties so the final sheet has the desired properties (51). Properties of recycled fibers differ from those of fibers prepared directly from wood. For example, recovered chemical fibers have lower freeness, an apparent viscosity leading to different water drainage characteristics on paper machines. Recovered fibers also have iacreased apparent density, lower sheet strength, iacreased sheet opacity, inferior fiber—fiber bonding properties, lower fiber sweUiag, lower fiber flexibiUty, lower water reteatioa, reduced fiber fibrillatioa, and much lower internal fiber delamination. 

In 1993, nearly 36 million tons of paper were recovered in the United States, twice as much as in 1980 (54). Eor the first time, more paper was recovered in the United States than landfilled. As a result, 11 million fewer tons of paper were landfilled in the United States in 1993 than in 1987. This saved more than 69 X 10 m (90 x 10 yd ) of landfill space. In 1995, recovered paper accounted for 31.5% of the fiber used to manufacture 84.1 million metric tons of paper products (54). Annual capital spending for paper recycling projects from 1995 to the year 2000 is estimated to average 2 biUion (55). The American Eorest Paper Association (AE PA) estimates U.S. consumption of recovered paper will increase 4.9% per year through the year 2000, nearly twice the total paper industry capacity growth rate (56). Consumption of recovered paper in U.S. mills in 1997 is estimated at 35.6 million tons (57). 

Today, about 40% of newsprint is recycled and reused. In 1994 alone, recovered and recycled paper and paper products reached 40 million tons and are expected to reach 60 million by the year 2000 [108]. As more and more paper is being recycled, more and more unusable short fibers are being generated. Approximately 15 to 20% of the fibers are too short to be useful after repulping. The combination of short fibers with fillers, known as recycled paper sludge (RPS), is usually disposed of in landfills as waste paper sludge or subjected to incineration after dewatering [109]. 

Typically, recycled paper sludge is made up of approximately 50% cellulose, 10 % hemicellulose and 40 % other materials, and has a moisture content of about 60%. For example, with a dry ton of recovered paper for repulping, there is about 0.15 to 0.2 ton of dry short fibers generated. The wet weight of RPS will be up to 0.5 ton including water, short fiber and other solids known as fillers. Because of its high fiber content, RPS is the type of material that can be effectively utilized and converted into ethanol. The ideal method of producing ethanol from RPS is to use the simultaneous saccharification and fermentation (SSF) process. 

The target of fiber preparation systems is to modify the raw materials for paper production so that the stock suits the requirements of the paper machine as well as those of the finished paper or board. Raw materials are virgin fibers from different sources such as chemical pulps from hard- or softwood or mechanical fibers like SGW, PGW, TMP or CTMP. The largest portion of raw materials today is recovered paper which is processed into secondary or recycled fibers. The recovered paper grades differ a lot as regards fiber compostion and cleanliness levels (see Vol.l). Therefore the processing systems have to take into account these differences as well as the various quality requirements of the finished stock. 

Ltd., of Chandigarh, India, produces a recycled PE/PP/wood composite for use as a wood substitute, or as a filler in cast polyester for furniture. Natural Eiber Composites Inc., of Baraboo, WI, commercialized a pelletized wood fiber-filled plastic using recovered paper or wood fibers with PP, HDPE, or PS. " Mikron Industries manufactures a wood-plastic... 

PET scrap suitable for glycolytic recycle includes production waste, fibers, film, flake, and bottles. In a practical system, major contaminants are separated from feedstocks, e.g., bottle waste is cleaned and separated from a polyethylene base, paper labels, metallic caps, and liners. For many end uses, colored PET must also be segregated. (Highly modified copolymers, glass-reinforced resin, fiber, or fabric blends are not suitable for glycolysis. These can only be recovered by methanolysis/hydrolysis.) Since reaction time depends on surface area, PET feedstocks must be reduced to relatively small particles by grinding, cutting, etc. 

Dry the crucibles and precipitates for at least 1 hour in an oven at 110°C, or preferably overnight at that temperature, as designated by your instructor. When the crucibles have cooled to room temperature, weigh each one on the analytical balance, and record your masses in TABLE 16.IB. Transfer the circles of glass fiber filter paper and the AgCl precipitate to a beaker on the reagent bench marked AgCl PRECIPITATE. This will also be recycled to recover the silver for future use. Finally, clean the crucibles, and return them to the equipment bench. 

Paper broken during the manufacturing process has to be recycled and fibers are recovered from the white water of the paper machine in a saveall. White water is fed back from the paper machine to the approach flow system and stock preparation. Fresh water is supplied to the paper machine. 

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