A breakthrough in ash recycling – UPM
In Germany, the UPM Schongau paper mill and on-site partner, SMI, have jointly developed a new process for precipitated calcium carbonate (PCC) from residual ash. The new process is hailed as a breakthrough in many ways by forest industry major UPM as a new smart way to use residue ash while saving a significant amount of energy.
According to UPM, around 30 percent of the calcium carbonate, manufactured by burning natural limestone at a very high temperature, needed by the paper mill can now be replaced by the precipitated calcium carbonate (PCC) recovered from the residual ash.
The new product, “ENVIROFIL30 PCC”, has many positive impacts at the mill. On an annual basis, carbon dioxide (CO2) has been reduced by 10 800 tonnes, energy consumption has gone down by 13.5 GWh and truck movement in and out of the mill have been reduced 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, said Heiko Hilbert, Head of the PCC project at UPM Schongau.
Committed research with a trusted partner
The research with SMI into PCC 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, explained Heiko Hilbert, who is also one of the people behind the patent that made a smaller particle size possible.
The cooperation with SMI is described as “open and full of trust” improving over time.
There is no chance of reaching ambitious goals together if you do not know your partner very well, Hilbert pointed out.
Several recycled ash products
UPM has set itself a zero solid waste company by 2030. Most of the solid waste produced by UPM is in the form of ash that is generated from its bioenergy production. At present, 96 percent 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.
So far, UPM Schongau has been producing ash for several uses. ELURIT replaces caustic soda in bleaching the pulp in papermaking. 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, ended Heiko Hilbert.