Suzano minds its Ps and Qs

With the installation of a new bleach plant, the difficult old unit no longer haunts the Suzano Bahia Sul mill in Brazil

It's difficult to say what Mary Shelley would have thought of her legendary monster, Frankenstein, being compared with a bleach plant in a pulp mill. However, to the dismay of the staff at the Suzano Bahia Sul mill near Sao Paulo, Brazil, the comparison was all too apt.

A new bleach plant that started up in late 2003 has rid the mill of the monster though. The result has been improvements in production, quality, safety and peace of mind.

Built in 1957, the mill sprawls across a large area as new equipment was added over the years. Unfortunately what was once new is now old and in need of replacement or upgrading. The original pulp mill had a capacity of 50 mtpd. Today, Suzano can produce more than 1,500 mtpd from its two lines, one continuous (1,100 mtpd), one batch.

The mill operates as two units: B and C. The B unit produces 525,000 tonnes of pulp, paper and board. There are four paper machines in Unit B: B5-B8. Unit C, which is actually about 12 km from the rest of the mill, operates two paper machines with a total capacity of 54,000 mtpy of coating base paper. The two machines (Cl and C2) use pulp from the Suzano mill. (Unit A was an adjacent tissue mill that has been sold to another company.)

As with most other mills approaching 50 years of age, upgrading is essential. Suzano Bahia Sul had (and has) two projects underway: P and Q. The former deals with increasing paper production. In Phase I, Suzano spent $35 million to rebuild the B8 paper machine in the first quarter of 2004. Voith was responsible for the upgrade, which saw speed increase to 1,200 mpm and production jump from 112,000 mtpy to 155,000 mtpy of printing and writing grades. Basis weights now range from 70-90 g/m^sup 2^.

Earlier, in 2002, B5 received an upgrade that saw its production rise from 75,000 mtpy to 90,000 mtpy of double coated woodfree grades. The machine's off-machine coater was also rebuilt.

Also due for a refit

Machine B7, similar to B8, is also scheduled for a rebuild, but the project still needs approval from the company. If approved, the rebuild would take just over a year. Machine B6 produces 4-layer board.

A new off-machine coater is also a possibility. It would cost about $90 million and could produce up to 230,000 mtpy.

Suzano's markets spread from South America to North America to Europe. Sixty percent of its paper goes out as cut size, the rest in rolls. Domestic shipments account for 60% of production. Suzano Bahia Sul is Brazil's leading producer of uncoated and coated printing and writing paper as well as paperboard.

Project Q is dedicated to the pulp side of the complex. Its objectives were to increase production (from 420,000 to 525,000 mtpy), improve environmental conditions (the mill is in a residential area), rebuild old installations and reduce its water consumption. Total cost was $111.8 million.

Water is a major problem in the area. Most of the water in the region is destined for the city of Sao Paulo and its 16 million inhabitants. So, there is a shortage. Still, the mill can operate comfortably on its allotment of 1.4 m^sup 3^/second. However, quality is a problem. As the municipality has no treatment system, the mill must treat incoming and outgoing flows.

Something that is not a problem for Suzano is wood. The company owns more than 430,000 ha of woodlands. However, not all is available for harvest. There are preservation areas planted with varietal species interspersed with the eucalyptus plantations. Brazilian law dictates that a certain amount of land be set aside for preservation.

In 2004, the company had 4.6 million m^sup 3^ of wood available. Yield in its forests is increasing. In 1980, it was 18 m^sup 3^/ha; in 2002 it had jumped to 40 m^sup 3^/ha. In 2006, the company expects to harvest 45 m^sup 3^/ha. There are two reasons for the growth: better research and the fact that more land that has better soil has become available.

The curve is flattening now, which may suggest the limit is being reached. New technology such as genetic modification may yet stretch the yield. However, this is still banned in Brazil.

Suzano Bahia Sul has two debarking lines at the mill but also debarks in the forest. Currently, 30% of the wood is delivered with bark and the rest is debarked in the forest. The goal is for a 25:75 ratio so the mill is almost there. The mill will probably not be able to debark 100% of its logs in the forest because some areas are too hilly.

Being a good neighbor

Noise was one of the main reasons why most debarking is done in the forest. As noted, the mill is in a residential area and the debarker had to be shut down at night.

As part of Phase I of Project Q, the mill installed a new wood handling system from Metso. The system consists of a wood infeed line, chippers and chip conveying. This line handles the debarked wood arriving at the mill. However, there is a bark separation roll conveyor to remove any remnants of bark left on the log.