Circular production of salts from fly ash

If we are serious about creating a sustainable, climate neutral society, we have to start using the materials we already have as often as possible.

The Ash2Salt technology extracts commercial salts from fly ash, a hazardous by-product from incineration. Valuable raw materials in the ash, such as the agricultural nutrient potassium, can be circulated and used again. This cuts the CO2 footprint of the salts by around 90% compared to traditional, virgin salt production.

The first full-scale Ash2Salt facility is set to open shortly near Stockholm, Sweden. The technology is also available in 12 countries all over the world thanks to a licencing agreement with Hitachi Zosen Inova.

Valuable raw materials from hazardous waste

Fly ash is a product of air pollution control at incineration plants. It is a hazardous waste due to high contents of heavy metals and chlorides. At the same time, it contains several valuable compounds which, until now, have been lost as the ash has been disposed of.

The Ash2Salt process washes the fly ash, and three commercial grade salts are extracted from the liquid: potassium chloride, sodium chloride, and calcium chloride.

After washing, the remaining ash can be placed on a landfill for non-hazardous waste. This represents a major change, since the hazardous properties of fly ash have always made it expensive and problematic to handle.

Research also indicates that the washed material may be adaptable for industrial use in the future.


Circular salt production with a fraction of the climate impact

Incinerating municipal waste destroys potentially harmful microbes and many contaminants. At the same time, valuable raw materials are concentrated in the residue, for example in the fly ash, making it possible to recover them at a large scale.

For all the three main salts produced by the Ash2Salt technology, the climate footprint is about one-tenth of traditional production.

  • Potassium is one of the key nutrients in fertiliser, crucial for agriculture to be able to grow the food we need. Today, it is mined, which causes large climate emissions, and production is largely concentrated to a few countries. Potassium chloride from the Ash2Salt process carries a carbon footprint 93% lower than the equivalent from the mining of virgin resources.
  • Common production of calcium chloride requires the mining and heating of limestone, another climate-intensive process. It is primarily used for de-icing roads and carries a 92% lower carbon footprint when produced with the Ash2Salt method.
  • Sodium chloride, known to most people as ordinary table salt, is one of the most used chemical compounds on the planet. Many industrial processes depend on large quantities of sodium chloride. As most of it comes from mining or the evaporation of sea water, the Ash2Salt technology lowers production climate emissions by 88%.