**Recycling of the Hardwood Kraft Pulp**

Jarmila Geffertová and Anton Geffert

*Technical University in Zvolen, Faculty of Wood Sciences and Technology Slovakia* 

### **1. Introduction**

264 Material Recycling – Trends and Perspectives

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**4. References** 

(electronic) 1436-2449

1273-6, London, United Kingdom

Council, Inc., Vermont, USA

7450, ISSN (electronic) 1097-9867

Chicago, Illinois, USA

0098-1354

According to "Key Statistics 2009 European Pulp and Paper Industry" CEPI member countries produce 21,6 % of world fibre production, while North America 37,4 % and Asia 23,8 % (Key Statistics, 2009).

Pulp made by kraft process is the most widely used raw material for paper and board production.

For paper and board production is not using exclusively fresh pulp fibres. The portion of recycled fibres increases gradually.

While the portion of new and recycled fibres used in CEPI countries was equivalent in 2008, the consumption of recycled fibres (as a waste paper) increases 2.6 mil. tonnes (fig. 1).

Fig. 1. Evolution of new and recycled fibres.

The year 2009 was the first year when CEPI countries consume more waste paper (44.9 mil. tonnes) than pulp (42.3 mil. tonnes) for production of 88.7 mil. tonnes of paper and board.

The usage level of recycled fibres is evaluated based on predefined parameters – waste paper utilization rate and recycling rate.

Recycling of the Hardwood Kraft Pulp 267

Nowadays adverse price evolution in the area of hygienic paper products is examined. Increased demand for basic raw material leads to the increase in price of pulp (about 40 %) and waste paper (about 80 %) (ŠK, 2010). This evolution was influenced by enormous demand of China for fibres and waste paper. Chinese expansion of paper and board production represents 180 % within the years 1999 and 2009 (MD, 2010). Mentioned negative evolution was influenced by earthquake in Chile; floods in USA and Portugal; transporters strike etc. All these factors conduce to the input increase and the price grow of

Recycling is implemented in paper production for centuries (from 105 A.C.). Initially the paper was made from fibres obtained from old cloth. The usage of wood fibres starts from

Europe has long tradition in the effort of the old paper re-usage. First notices are from 1695 (Denmark), chemical processing by decolouration was patented in England in the year 1800. Technical importance of recycling begins to increase in 20th century. Nowadays the development is focussed on old paper processing. Old paper utilization is important for

• Decrease of specific fuel and electricity consumption for paper production,

because of its regeneration ability after usage, collection and separation.

fibres are routinely recycled for 3- to 5-times (Souček, 2009).

regional relatives. It depends on paper industry production relatives of country.

• Improvement of production economics, decrease of capital and operating costs,

• Conduce to environment protection (Blažej and Krkoška, 1989; Hnětkovský, 1982

Paper and paper products are the most widely used transmission form of written and printed information and packaging material. Paper and board consumption is authoritative and validated parameter of society economic and cultural level. Therefore used paper is the most widespread waste. So paper occurs everywhere where people are living. Besides of very good useful paper properties, paper provides several advantages contrary to competitive material. Firstly the paper is degraded relatively quickly and without negative effect on environment. Then paper represents valuable secondary raw material mainly

Waste paper occurrence, its quality and amount vary within time periods, seasons and

European paper industry, companies focussed on paper collection and waste paper vendors are persuaded that it could be achieved more in long-term environment protection and that "paper cycle" could be closed whereas primary and secondary fibres complete each other. Paper production, processing and utilization create waste paper which is an important source of secondary fibres. If this paper is not used, it represents valueless waste and it contaminates the environment. Nowadays waste paper is not considered as waste but it represents valuable fibre raw material which could be multiply used - recycled. Secondary

hygienic paper products at about 10 % at average (ŠK, 2010).

the half of 19th century (Blažej and Krkoška, 1989).

• Natural fibres and wood material savings,

**1.1 Paper recycling** 

national economy because of:

• Water savings,

and 1983a, b).

The waste paper utilization rate (percentage ratio of waste paper consumption to total paper and board production) in CEPI countries reaches v 50.7 % and recycling rate (percentage ratio of waste paper consumption to paper and board consumption) 72.2 % in 2009. Thereby the obligation of 13 different sectors of paper chain to achieve recycling level 66 % in 2010 was surpassed (www.paperrecovery.eu, 2007).

Figure 2 illustrates the evaluation of waste paper usage rate and recycling level within 1991 and 2009 in CEPI countries (Key Statistics, 2009).

Fig. 2. Evaluation of waste paper usage rate and recycling level in CEPI countries.

Consumption of paper and board per inhabitant is one criteria of industrial and cultural country level. Average world consumption of paper and board was 56.3 kg per habitant in 2004. However, paper and board (P&B) consumption of some countries (USA, Finland) was around 300 kg per inhabitant in 2004 (Lešikár, 2006).

Table 1 indicates actual paper and board consumptions of some world countries. (http://swivel.com/charts/2381-Paper-Consuption-per-capita-by-Country).


Table 1. Paper and board consumption of some world countries in 2009.

The waste paper utilization rate (percentage ratio of waste paper consumption to total paper and board production) in CEPI countries reaches v 50.7 % and recycling rate (percentage ratio of waste paper consumption to paper and board consumption) 72.2 % in 2009. Thereby the obligation of 13 different sectors of paper chain to achieve recycling level 66 % in 2010

Figure 2 illustrates the evaluation of waste paper usage rate and recycling level within 1991

**Recycling rate [%] Utilization rate [%]**

**64,6 66,7**

**1991 2000 2007 2008 2009**

Consumption of paper and board per inhabitant is one criteria of industrial and cultural country level. Average world consumption of paper and board was 56.3 kg per habitant in 2004. However, paper and board (P&B) consumption of some countries (USA, Finland) was

Table 1 indicates actual paper and board consumptions of some world countries.

Finland 334 Germany 235 Greece 76,2 USA 312 Switzerland 210 Bulgaria 35,8 Canada 277 Great Britain 208 Russia 34,5 Belgium 264 Luxemburg 198 Romania 25,6 Denmark 257 Italy 195 China 33,6 Japan 250 France 183 Vietnam 6,3 Austria 245 Spain 166 Cuba 4,7 Germany 235 Czech Rep. 116 India 4,4 Nederland 227 Hungary 82 Iran 9,8 Sweden 223 Poland 80 Iraq 1,4

Consumption of P&B [kg/inhabitant]

Fig. 2. Evaluation of waste paper usage rate and recycling level in CEPI countries.

(http://swivel.com/charts/2381-Paper-Consuption-per-capita-by-Country).

Country

Table 1. Paper and board consumption of some world countries in 2009.

**45,4 48,4 50,7**

**49,2**

**72,2**

Country

Consumption of P&B [kg/inhabitant]

was surpassed (www.paperrecovery.eu, 2007).

and 2009 in CEPI countries (Key Statistics, 2009).

**40,3**

**0,0 10,0 20,0 30,0 40,0 50,0 60,0 70,0 80,0 90,0 100,0**

Country

**39,1**

around 300 kg per inhabitant in 2004 (Lešikár, 2006).

Consumption of P&B [kg/inhabitant] **52,0**

Nowadays adverse price evolution in the area of hygienic paper products is examined. Increased demand for basic raw material leads to the increase in price of pulp (about 40 %) and waste paper (about 80 %) (ŠK, 2010). This evolution was influenced by enormous demand of China for fibres and waste paper. Chinese expansion of paper and board production represents 180 % within the years 1999 and 2009 (MD, 2010). Mentioned negative evolution was influenced by earthquake in Chile; floods in USA and Portugal; transporters strike etc. All these factors conduce to the input increase and the price grow of hygienic paper products at about 10 % at average (ŠK, 2010).

### **1.1 Paper recycling**

Recycling is implemented in paper production for centuries (from 105 A.C.). Initially the paper was made from fibres obtained from old cloth. The usage of wood fibres starts from the half of 19th century (Blažej and Krkoška, 1989).

Europe has long tradition in the effort of the old paper re-usage. First notices are from 1695 (Denmark), chemical processing by decolouration was patented in England in the year 1800. Technical importance of recycling begins to increase in 20th century. Nowadays the development is focussed on old paper processing. Old paper utilization is important for national economy because of:


Paper and paper products are the most widely used transmission form of written and printed information and packaging material. Paper and board consumption is authoritative and validated parameter of society economic and cultural level. Therefore used paper is the most widespread waste. So paper occurs everywhere where people are living. Besides of very good useful paper properties, paper provides several advantages contrary to competitive material. Firstly the paper is degraded relatively quickly and without negative effect on environment. Then paper represents valuable secondary raw material mainly because of its regeneration ability after usage, collection and separation.

Waste paper occurrence, its quality and amount vary within time periods, seasons and regional relatives. It depends on paper industry production relatives of country.

European paper industry, companies focussed on paper collection and waste paper vendors are persuaded that it could be achieved more in long-term environment protection and that "paper cycle" could be closed whereas primary and secondary fibres complete each other.

Paper production, processing and utilization create waste paper which is an important source of secondary fibres. If this paper is not used, it represents valueless waste and it contaminates the environment. Nowadays waste paper is not considered as waste but it represents valuable fibre raw material which could be multiply used - recycled. Secondary fibres are routinely recycled for 3- to 5-times (Souček, 2009).

Recycling of the Hardwood Kraft Pulp 269

fibre shortening is observed within increasing count of utilization cycles. Mentioned

Experiences gained during old paper utilization prove that these fibres show significantly different properties comparing to freshly prepared fibres (Blechschmidt, 1979; Nordman, 1976; Laivins and Scallan, 1993; Hubbe et al., 2007; Howard, 1990, 1994, 1995; Nazhad and Paszner, 1994; Phipps, 1994; Ackermann et al., 2000; Shao and Hu, 2002; Hubbe and Zhang, 2005; Nazhad, 2005). Fibre re-utilization creates extremely non-homogenous mixture of variously old fibres. Old paper is composed by all types of manufactured paper and board. Additional inhomogenity is caused by the presence of fibres used for several times but

Pulp fibres are modified within the paper production by beating. Whereas the beating condition optimization is very important because of created fibrillation of fibre surface, release of fine portion and cell wall delamination. Paper rigidity increases during the beating. However recycled fibres repeated beating and drying lead to the decrease of inter-

Göttsching (1976) detected by strength measuring at zero-span of jacks that recycled fires resistance does not change practically. Decrease of paper resistance made by recycled fibres

Decrease of bonding ability and strength of recycled fibres bring the improvement of several utility characteristics as increased velocity of dewatering and drying, air permeability, blotting paper ability, improvement of light diffusion, opacity, and dimensional stability of paper (Göttsching and Stürmer, 1975), which is linked with decreased fibres ability of

Fibres swelling in width orientation and increase of wet fibre flexibility prove inner fibrilation caused by beating. Beating process creates submicroscopic areas in lamellar structure of kraft pulp fibre cell wall. Mentioned areas have tendency to close themselves

Recycling process of kraft pulp fibres was observed on white kraft pulp sample prepared

Pulp sample was processed into sheets of surface weight 800 – 900 g.m2 and brightness

Original sample after first processing by defibering, milling and drying represents zero recycling. Following pulp fibres processing simulated recycling. Pulp fibres undergo recycling for 8 times. Simulation could be considered as sufficient because usually pulp

Pulp was returned back into defibering, milling and drying process. The beating value was chosen as 29 °SR because of achieving sufficient strength of paper sheets without redundant

modifications reflect in paper properties (Blažej and Krkoška, 1989).

fibre bonding potential (Stürmer and Göttsching, 1979; Peng et al.,1994).

could be explained as the consequence of inter-fibre bond strength decrease.

semi-reversibly during drying (Jayme and Büttel ,1968; Paavilainen, 1993).

swelling in contact with water (Ackermann et al., 2000).

fibres are re-utilized for 4 to 5 times in practice.

fibre weakening and ensuring the possibility of next recycling.

unequally (Attwood, 1983).

**2. Experimental** 

82.7 % MgO.

from hardwood mixture.

Whereas the majority of mixed grades and OCC grades of recovered paper primarily find use in the production of packaging papers and board (84 %), almost all deinking grades (88 %) go to graphic paper production (Putz, 2000).

Waste paper participates in total paper production (60 %) mostly in Nederland and Great Britain. This limit is almost reached in Germany. Whereas Nordic countries that have sufficient wood raw material source are using only 10 – 15 % of waste paper as a secondary fibres (Milichovský, 1994).
