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Secondary fibres lead the way in Europe

The latest in German papermaking technology was at the forefront during a press tour of Voith installations in late 2000. Two mills were featured in a whirlwind visit — Lang Papier in Ettringen and t…

The latest in German papermaking technology was at the forefront during a press tour of Voith installations in late 2000. Two mills were featured in a whirlwind visit — Lang Papier in Ettringen and the Haindl mill in Schongau. Both mills are special in their own way: Lang for its Compact PM 5 and Schongau for its feat of dismantling an old paper machine and installing a new one in 56 days (paper to paper).

Now owned by the Finnish company Myllykoski (since 1987), the Ettringen mill opened in 1897 producing groundwood pulp. Its first paper machine was installed in 1910. In 1996, PM 4 was the first machine equipped with a Janus Concept online upright calender. The Compact PM 5 was installed in 1999 to produce 280 000 tonnes per year (t/y) of SC paper and newsprint using a mostly deinked fibre furnish (See article by Palm et al, Pulp & Paper Canada, April 2001). The first paper was produced on August 22, 1999.

In late 2000, the mill’s third deinking line started up. The mill can now produce 500 000 t/y of deinked pulp from old magazines and newspapers. There is one DIP processing line for each of the mill’s three paper machines. The newest DIP line is dedicated to PM 5. At the time of installation, it had the world’s largest flotation deinking capacity, 880 t/d accepts in one line.

SC furnish for PM 5 is a mix of DIP (75%), groundwood (still made at the mill, 20%) and kraft (purchased, 5% when needed). Fillers may also make up some of the furnish. Furnish for newsprint is 85% DIP, 15% groundwood. Maximum machine speed is 1800 m/min. Wire width is 8.9 m and trim width is 8.1 m.

The Compact refers to the smaller “footprint” the machine makes on the mill compared to a conventional paper machine. While time may mean money to some, to a mill, space is money. For example, the single online calender means a space saving of about 28 m, a dollar saving of approximately US$2 million.

PM 5 features Voith’s DuoFormer TQ gap former and the Tandem-NipcoFlex shoe press. The NipcoFlex is claimed to be the world’s fastest shoe press for graphic papers with a design speed of 1600 m/min. Both presses have the shoe roll in the top press position. This was done for easier maintenance and has had no effect on quality. Dryness after the press can reach 54 to 58% solids for SC papers, even with an ash content of up to 30%. For news, the dryness is 49 to 54%.

The dryer section is divided into five drive groups. The web run is supported throughout the entire dryer. There is a ropeless tail threading system from Fibron (now owned entirely by Voith). Broke is removed by a belt conveyor in the mezzanine.

The eight-roll inclined Janus MK2 online calender can be run three ways: running all the nips, top bypass and bottom bypass. The latter is used for newsprint production. The top and bottom calender rolls have the Nipcorrect system with 44 zones. The Compact PM 5 is the first machine using a wood-containing furnish to run with this kind of press and calender.

The Sirius R125/2 reel produces a glossy, smooth web at high speeds. There is a centre drive for the primary and secondary arms.

The fully automatic sequence of a knife change takes less than 30 seconds. Rolls up to 3.7 m in diameter are possible.

As for quality objectives, for SC-A, they are 68 brightness, 45% gloss (Hunter 75), porosity of 20 mL/min and a PPS-S10 roughness of 1.2 um. All targets have been met and even exceeded.

Mill officials noted that it is cheaper to produce stone groundwood pulp in Germany than it is DIP. Still, the mill would like to buy more secondary fibre but it is not available. The quality of incoming recovered paper is the key to final paper quality. At Ettringen, a recovered paper hall capable of storing 25 000 t has been built. Once trucks are unloaded, the paper is put on conveyors and sent to the hall. The system is entirely automated, including the conveying of paper to the pulpers.

Another new Voith machine will be installed at a location in Germany yet to be announced. It will use the same concept to produce 280 000 t/y of newsprint from 100% DIP. Start-up could be as early as 2002.

A mill in a hurry

On May 2, 2000, Haindl’s Schongau mill shut down its old PM 9 and carefully began to dismantle it. (It had been sold to the Dong Ying Huatai Paper Company in China and is expected to restart in May 2001.) Installation began almost immediately on its new PM 9. On June 28, 2000, the first paper from the new machine went on the reel. In 56 days, the mill had installed a new paper machine producing 230 000 t/y of SC-B paper from a 100% DIP furnish.

Design speed of the Voith machine is 2200 m/min. Operating speed is 1500 m/min (at a basis weight of 56 g/m2). The basis weights range from 45 to 56 g/m2. Wire width is 6.8 m, trim width is 6 m.

The Voith DIP plant consists of several parallel deinking lines of different sizes. Pre-flotation has five lines in the primary stage, each with six cells and, in the secondary stage, two lines each with four cells, one line with three cells and one line with five cells. The post-flotation primary stage has three lines each with five cells and the secondary stage two lines each with three cells. Besides the DIP furnish, which is peroxide bleached and post refined, an amount of filler is also added: PCC or clay. Specialty Minerals has an on-site PCC plant. Filler content can reach 34%, some of which is added (15 to 18%); the rest is in the DIP. One of the advantages of DIP versus virgin fibre is the amount of filler in DIP. This can provide good ink hold-out and better picture impression. Schongau’s DIP furnish is about 40% OMG and 60% ONP.

Opened in 1887, the mill now runs three paper machines producing 650 000 t/y of newsprint and SC grades. Its pulp furnishes are DIP (1900 t/d) and TMP (200 to 300 t/d made from sawmill chips). The new PM 9 added 70 000 t/y of extra capacity to the mill.

The new machine was built to improve SC-B quality for roto and offset heatset printing, reduce noise levels and decrease cooling water use. The mill now uses 30 000 m3/d of water (cooling water, mill effluent and evaporation). Effluent levels are 7 to 8 m3/t/d.

As with Ettringen, the new paper machine features a ModuleJet headbox with CD control, DuoFormer TQv, Tandem NipcoFlex press, TopDuoRun dryer section, an online Janus MK2 calender (10-roll — 2 x 5, rather than the 8-roll as found at Ettringen) and Sirius reel.

Running this much DIP furnish in an SC-grade paper makes quality control a vital aspect of the process. The mill has a moisture profiler scanner at the second vacuum roll to control the profile before the second nip. Therefore, there is an even profile coming out of the press. This ensures a stable run.

After the dryer section there is an ABB quality control system. It measures basis weight, moisture, ash and sheet temperature. There is a moisturizer at the end of the dryer. The section before the calender is critical because the mill needs a very even moisture profile before the calender for SC grades. ABB also supplied the quality control system that is installed ahead of the reel.

The new machine had a steep start-up curve, producing an average of 279 t/d in July 2000 at a speed of 1343 m/min and an efficiency of 45.8%. In August, average production jumped to 480 t/d at a speed of 1390 m/min and an efficiency of 75.5%. An incremental improvement was achieved in September — 481 t/d, 1401 m/min and an efficiency of 75.7%. (Upcoming technical papers in Pulp & Paper Canada will provide a more detailed explanation of the mill and some of the equipment.)

Mill manager E. Krauthauf said that markets were good at the time, that start-up was “just in time”. PM 9 entered a healthy market for magazines, flyers and catalogues. However, the mill now makes less standard news and this market was also flourishing. The Internet, Krauthauf explained, did not take away ads from newsprint as predicted. He added that at least one German paper was limited by its presses, not a lack of advertising. In October, the situation was such that transport trucks were awaiting the paper as it was coming of
f the wrap line.

And, he added, he expects no influence from the Net in the near future. Krauthauf said that one US consultant has forecast a 2.45 million tonne drop in demand for newsprint by 2003. He said the analysts had the figure right, only that it would be an increase.

Production from Haindl’s four German mills is destined mostly to central Europe: 90 to 92%. The rest goes overseas. This is dependent on the grade however. For example, a lot of the SC-B paper ends up in the US.

Krauthauf said that the Schongau mill employs 580 people, of whom 136 are staff. There are 34 apprentices: 16 papermakers, 8 millwrights, 8 electricians and 2 office workers. “This is the future,” Krauthauf said. “We have good young people.” Foremen must also be graduates of a technical school where they follow a curriculum specifically designed for them.

Besides Voith, other suppliers to the Ettringen and Schongau projects included:

Ettringen

Schongau