Mercer's giant leap

Pulp & Paper, Mar 2005 by Toland, Justin

The U.S.-owned company's new $1.3-billion Stendal market pulp mill in eastern Germany steps up with 552,000-tonne/yr of NBSK

Pulp and papermakers often talk about expanding the business "step by step:" a sensible approach. But sometimes, the next step cannot be a small one-it must be a "giant leap." Taking that step requires the "courage to change," points out Jimmy Lee, CEO of Mercer International. Mercer has just taken the courageous step of starting up a new 552,000-mtpy market pulp mill, Zellstoff Stendal (Stendal), located in Arneburg, Sachsen-Anhalt, eastern Germany. In the process, the U.S.-owned pulp and papermaker has more than doubled its NBSK capacity (Mercer's Rosenthal mill, Blankenstein, Thuringia, Germany produces approximately 300,000 mtpy market pulp).

The new mill, which started up at the end of July, was first announced in January 2000. As is often the case with projects of this size, it took some time for financing for the Euro 1 billion ($1.3 billion) scheme to be put in place. The bulk of the funding comprised a loan of Euro 819 million arranged by Bayerische Hypovereinbank of Munich and partly underwritten by Nord-LB, Hannover and Halifax-Bank of Scotland. However, Mercer had to wait until June 2002 for EU approval for support and subsidies of around Euro 250 million offered by the German government. Mercer owns 64% of Stendal, German electricity giant, RWE, holds a 29% stake, while the remaining 7% belongs to Fahr Beteiligungen AG, owner of the industrial park where the mill is located.

With the money in place, the project moved quickly. RWE, which was awarded the Euro 716 million turnkey construction and erection contract, broke ground on August 26, 2002. The project required 130,000 m^sup 3^ of concrete, 14,200 tonnes of reinforced concrete, and 48,000 pre-assembled parts. At the height of construction, there were 2,500 people working on what was the biggest building site in Sachsen-Anhalt. The machine house was completed in August 2003, an occasion marked by a visit from German chancellor, Gerhard Schroder.

Metso supplied the complete fiberline, from wood handling to finished bales, as well as a millwide automation system, an order worth Euro 135 million in total. Mercer awarded the contract for the black liquor evaporation plant (670 mtph), recovery boiler (3,250 tonnes dry solids/day) and recausticizing plant (8000 m^sup 3^/day) to Andritz. Other key suppliers included Purac (biological water treatment), Sulzer Pumps (pumps and agitators), and Wiessner (air engineering). All the major suppliers were well established and performed in line with their reputations, notes Lee. "We had no major issues with the suppliers," he says.

As process engineer Eberhard Dobschall explains, the startup of the mill was a very special moment for all involved: "At the weekend we filled the first digester with chips and added the first liquor on Monday, and when the first pulp came out the following Wednesday, our hairs stood on end. We felt very proud."

Raw materials

Stendal's pulp is made from 70-80% pine, 20-30% spruce. Wood procurement is the responsibility of subsidiary company, ZS HoIz, while a second daughter company, ZS Transport, is responsible for both internal logistics and wood chip transport and product shipments to all markets. Stendal is PEFC certified and will source wood exclusively from sustainable forests within a 300-km radius of the mill, as well as use chips from sawmills.

According to Dobschall, the mill aims to use 70% own-produced chips and 30% from outside. Daily consumption when the mill reaches full output will be 9,000 m^sup 3^ solid wood. There are three weeks roundwood storage space on site.

The logs are processed using Metso Chip Way technology, consisting of two debarking and chipping lines. Each line can handle up to 300 m^sup 3^ solid wood/hour. The wood infeed system-GentleFeed-conveys the logs into the debarking drum on top of moving lamellas, rather than using chains or sprockets, the aim being to eliminate wood breakages and improve yield and chip quality, thereby decreasing the need for bleaching chemicals.

Together with the infeed system, the Easy Tyre debarking drums and Camura GS chippers are designed to minimize wood losses and maximize the uniformity of chips destined for the digester. The mill also has a bark press that will be used in winter when the bark is less dry. Unused bark is stored and then burnt in the bark boiler to generate energy. Stendal's bark and recovery boilers between them generate 90 MW of energy. Since the mill needs only 55 MW, the remainder can be sold to electricity suppliers. Mercer believes the mill will be an "industry leader" in terms of efficient production and good environmental performance.

Only chips of the right size and quality are made into pulp; those that are too large are rechipped, while fines go to the bark storage area prior to being burnt in the bark boiler. Chips produced onsite and those brought in from sawmills are stored in separate 60,000-m^sup 3^ chip piles for quality control reasons.