Classification of pulp and paper mills

The high degree of process-integration in pulp and paper industry implies that the concept of BAT must be related not only to separate processes, systems or lines, but also to the whole integrated units. For instance, in order to reduce effluent volumes, water has to be recirculated typically from the paper mill to the pulp mill in addition to internal loops in both parts of a mill.

At the same time, a certain product may be manufactured through various different processes and systems and it may be equally relevant to compare such different options, although based on quite different processes, when considering BAT. For instance, newsprint may be manufactured from several different pulp sources such as stone groundwood (SGW), pressurised groundwood (PGW), thermomechanical pulp (TMP), refiner mechanical pulp (RMP), chemithermomechanical pulp (CTMP), sulphite pulp (Si), bleached softwood kraft pulp (BSKP), and/or deinked pulp (DIP). Different furnishes will of course give rise to different emissions.

As pulp and paper products are highly diverse and applied processes even for one and the same product may vary greatly, many factors of production technology must be taken into account to guarantee a high level of environmental protection. The best techniques for the pulp and paper industry cannot be defined solely by describing unit processes. Instead, the whole installations must be examined and dealt with as entities.

In a document supplied by Finland to the EIPPCB [J. Pöyry, 1998 b], a proposal was made how to classify the pulp and paper industry operating in the European Union by distinguishing the technical properties of the installations and their product range. Following this proposal, the technically diverse installations in the EU area are presented using a grouping of 9 main classes.

This classification scheme is product-orientated i.e. distinguishes BAT for different pulp and paper products.

In Figure 1.1 the relationship between the amount of mills and capacities on a European level according to this classification is illustrated.

Capacity (%) Mills (%) 0

10 20 30 40 50 60 70 80 90 100

Non-integr. pulp mills (incl. DIP, TMP) RCF-based p&b (tissue not included) Integr. bleached kraft pulp & paper Integr. unbleached kraft pulp & paper Integr. sulphite p&b mills

Non-integr. fine paper mills Integr. woodcontaining p&b mills Tissue mills

Speciality paper mills

Figure 1.6: Capacities versus amount of mills in Europe

[According to J. Pöyry, 1998; changes made by EIPPCB]. In this study the 9 main classes of the classification scheme are further subdivided in 33 subclasses according to different end products

However, In the European paper industry there is a trend to use a mixture of raw materials as fibre furnishes (e.g. mixture of different types of virgin fibres and recovered fibres). There are also a lot of mills in Europe that are only partly integrated or use fibre mixtures, which are not covered by the proposal. For example there are tissue mills using 10%, 20%, 30% and so on till 90 or 100% of recovered fibres. These mills can not only be described on a product-orientated level. Furthermore, several of the mills are conglomerates giving problems in allocating the total discharges to the different pulp and/or paper types produced when they are not strictly described on a process level as proposed within the BREF.

The process of pulp and papermaking consists of quite many stages. Besides the fibrous material different chemicals and a great amount of water and energy in the form of steam, fuel oil or electric power is required in the process. The wide range of processes involved in the manufacture of pulp and paper can be broken down into a number of unit operations for the sake of discussion. A sequence of operations can be described from raw materials to product but individual processes will not involve all the operations and some are mutually exclusive alternatives.

Bearing in mind that there is no single right or wrong proposal but only reasonable and manageable proposals preference were given to classifying the European Paper industry as described below. To obtain clearer arrangements of the variety of processes involved, the most important pulp, paper and board manufacturing processes are described separately for five main classes that are described in separate chapters in this document. The main types of pulp and paper manufacturing are sub-divided in several sub-classes. The proposed structure of the European pulp and paper industry and the composition of the BREF are shown Figure 1.7. It strikes after a description of the major differences of pulp and paper production from an environmental-point-of-view:

KRAFT PULP &

Figure 1.7: Classification of pulp and paper mills proposed by this document including cross-references to the relevant chapters for those mills

The kraft pulping process is described in Chapter 2. Within kraft pulping emission levels associated with the use of BAT for bleached and unbleached grades are distinguished. The BAT emission levels for non-integrated and integrated kraft pulp mills are both given in this chapter.

The impact of the paper mill can be regarded as included for water discharges within the uncertainties given. On the other hand, as paper drying is more energy consuming than pulp drying figures for energy consumption and air emissions will differ between integrated and non-integrated pulp mills. These aspects are discussed in this chapter. However, the corresponding sections of the papermaking chapter (Chapter 6) have to be considered when determining BAT for integrated kraft pulp and paper mills (available techniques for papermaking). Some process steps of kraft pulping are similar for all ways of pulp manufacturing (e.g. wood handling, drying) and are therefore described only once and references to other parts of the documents are given.

The sulphite pulping process is described in Chapter 3. The sulphite process is much less uniform (e.g. different bases and pH-values) than the kraft pulping process which makes it more difficult to select BAT. The description is concentrated on the major sulphite pulping process in Europe, the magnesium sulphite pulping. Some additional information on NSSC and dissolving pulp will also be given in this chapter.

Mechanical and chemi-mechanical pulping is described in Chapter 4. Groundwood pulping, TMP and chemi-mechanical pulping (CTMP) has been distinguished. Most mechanical pulping is integrated with paper manufacturing. Therefore, the emission levels associated with the use of BAT for both mechanical pulping and papermaking are given in the Chapter 4. However, the corresponding chapter on papermaking (Chapter 6) has to be taken into account to identify the techniques to consider in the determination of BAT for integrated mechanical pulp and paper mills. Cross-references are given to other sections of the document to consider.

Recycled fibre processing is described in Chapter 5. BAT associated levels for processes with and without de-inking are distinguished thereby discussing some further differences in recovered fibre preparation as for e.g. tissue, LWC/SC, carton-board. The emission levels associated with the use of BAT presented are referring to integrated pulp and paper mills because most recovered fibres based mills are integrated mills. The corresponding chapter on papermaking (Chapter 6) has also to be taken into account. There, the techniques to consider in the determination of BAT as far as papermaking is concerned are described. Cross-references are given to the sections to consider.

Papermaking and related processes is described in Chapter 6 for the major paper grades being manufactured in European paper mills. Paper manufacturing at a site of its own (non-integrated paper mills) is dealt with in this separate chapter because, in numbers, most of paper mills in Europe are those mills. There is a certain overlapping to integrated pulp and paper mills that manufacture pulp and paper at the same site. Cross-references are given in those cases to the relevant sections.

No specific information on techniques to consider in the determination of BAT for board manufacturing was provided. Therefore, the document gives no separate description of the production of board. From environmental-point-of-view, the most important differences are between tissue and other paper grades and also between coated paper and board compared to uncoated paper and boards. Thus the following grades where distinguished within Chapter 6:

- Coated printing and writing paper as for instance coated fine paper used for printing, writing and copying

- Uncoated printing and writing paper as for instance uncoated fine paper.

- Tissue paper mills - Speciality paper mills

This group (mainly woodfree paper grades) is at the same time the major types of non-integrated paper mills in Europe. Of course, there are also non-integrated paper mills within that group.

Speciality paper mills is an extremely diverse grouping, which covers a high amount of different products. Speciality paper mills are often producing with more than one change of type per working day. Many speciality paper mills are also non-integrated paper mills. Because of its variety of products no emission levels associated with the use of BAT will be presented for speciality paper mills. The different products have their specific "environmental problems". The values and explanations presented in the BAT chapter should be taken as examples about emission levels to be expected from some types of speciality paper mills. They are not regarded as to cover the whole group of speciality papers completely.