Steyrermühl PM6 - An innovative conversion concept from graphic grades to high-quality kraft paper

On January 1 2024, HEINZEL GROUP completed the strategic acquisition of the Steyrermühl mill formerly owned by UPM. Ownership of the idled PM3 had already been transferred to HEINZEL in March 2023, allowing the conversion from supercalendered graphic grades to kraft papers. With this project, the company expanded its bleached and unbleached kraft paper production capacity by an additional 150,000 t per year.

This ambitious conversion included a new softwood and hardwood fiber line as well as rebuilding the gap former to a single, fully adjustable PrimeForm TW shoe-blade gap former, thereby ensuring high flexibility in basis weights ranging from 30-100 gsm at production speeds up to 1200 m/min. This concept also includes a new PrimeFlow AT headbox, a combination that results in lowest MD/CD ratios that are significantly lower than those from any other conventional gap formers in the market. What’s more, the ANDRITZ PrimePress X shoe press and upgrades in the steam & condensate system achieve significant energy savings. The new ANDRITZ VIB SteamTech profiling system and the PrimeCal soft calender technology further enhance the paper's surface quality, making it ideal for demanding kraft paper applications.

The equipment selection was proven in pilot trials via joint efforts between HEINZEL GROUP and ANDRITZ and features several innovations, most notably the use of a nonceramic drainage surface in initial forming phases. The nonceramic surface is a steel alloy which allows dramatically increased flexibility of pressure profile design, increased durability, and reduced CAPEX and OPEX considerations, all while offering very high wear resistance.

 After a challenging project lead time of only 16 months, the machine started up at the beginning of May 2024, perfectly on time. After an unbelievable period of just four weeks, the target production capacity for the first paper grades had already been achieved, and further optimization is still taking place. The PM6, with its new headbox and forming section, sustainably achieves the excellent profiles needed for high-quality end products.

The conversion at the Steyrermühl mill is the latest successful project in the long cooperation between ANDRITZ and HEINZEL GROUP.