Ragn-Sells AB (Sollentuna, Sweden; www.ragnsells.com) has partnered Hitachi Zosen Inova AG (Zürich, Switzerland; www.hz-inova.com) for the construction of a new plant that is designed to extract resources from flyash — a toxic byproduct of waste incinerators that normally ends up in landfills. When the facility starts up by 2022, it will be able to process flyash corresponding to half of the yearly production in Sweden.
The plant is based on the Ash2Salt technology, a patented process developed by Ragn-Sells’ subsidiary EasyMining AB (Uppsala, Sweden; www.easymining.se). In the process, flyash is first washed, creating a leachate solution containing chloride salts and heavy metals. The leachate is filtered, and the detoxified residue — with much smaller volume than the original ash — safely landfilled, or used in construction materials. The heavy metals are removed from the leachate by precipitation with sulfide, and ammonia recovered as ammonium sulfate, leaving a solution of chloride salts. The salts are then separated using a single evaporator by a patented process, to produce commercial-grade KCl, NaCl and CaCl2. One ton of flyash can contain as much as 400 kg of salts.
Each year, Sweden produces roughly 300,000 metric tons of fly ash. Around half is sent to a discontinued limestone quarry on the Norwegian island of Langøya (near Oslo). This practice means that neither resources nor toxic substances are extracted. Additionally, the Langøya quarry will reach maximum capacity and close down within a few years.
The plant, which is now under construction at Ragn-Sells’ Högbytorp site in Bro (outside Stockholm), is one of the largest single investments ever within the Swedish material-recycling sector.
