The UPM Schongau paper mill in Germany and on-site partner SMI developed together a new process for producing precipitated calcium carbonate (PCC) from residue ash. The new process is a breakthrough in many ways: it is a new smart way to use residue ash and saves a great amount of energy in the bargain.
Around 30% of traditional calcium carbonate, manufactured by burning natural limestone at a very high temperature, can now be replaced. The new product, ENVIROFIL®30 PCC, has many positive impacts at the mill. Annually it reduces CO2 emissions by 10,800 tonnes, lowers energy consumption by 13,500 MWh and has led to a reduction in heavy traffic on the roads, cutting the number of truck rides into and out of the mill by 2,500.
"The carbon dioxide that results from the burning process is captured directly within this alternative filler material. This way, it is not released into the environment. For us, this pioneering manufacturing process and the end product are perfect examples of innovation and resource efficiency leading us towards closing the natural resource circle," says Heiko Hilbert, leading the project at UPM Schongau.
Committed research efforts with a trusted partner
The research with SMI began some 20 years ago. The first trials on using recycled ash in replacing quicklime were made in 2002. The particles were both too abrasive and too large for filler production back then.
“The chemical process of turning ash into quicklime is only part of the solution. Many other factors have had to be considered, developed in detailed work together with the laboratory and UPM’s research centres and perfected,“ explains Hilbert, one of the persons behind the patent that made a smaller particle size possible.
The cooperation with the partner is open and full of trust and has only improved over time. “There is no chance of reaching ambitious goals together if you do not know your partner very well,” Hilbert points out.
Hectic research on recycling ash underway
Most of the solid waste produced by UPM is ash generated by bioenergy production. At present, 96% of the ash is used in soil construction, cement and brick industries or as fertilisers. The ash composition is always thoroughly analysed before being reused. The ash that is unsuitable for recycling is sent to landfills. UPM is to become a zero solid waste company by 2030.
So far, UPM Schongau has been producing ash for several uses. ELURIT replaces caustic soda in bleaching the pulp in the paper making. Cinerit is suitable for soil construction. UPM Schongau will share its expertise with other UPM mills although the process has to be modified to the specific needs and resources of each site.
“We are interested in extending the reuse of our mineral ash product ELURIT both internally and to other industries. Ash can be reused in UPM’s processes in many ways. We have a lot of ideas and many of them have already been realised at the mill and more widely throughout UPM,” says Hilbert.
Text: Saara Töyssy