Hazardous ash becomes clean road salt and fertiliser
The environmental company Ragn-Sells is now launching a new technique to extract pure salts from the fly ash which is produced when waste is incinerated. The global patent, Ash2Salt, owned by EasyMining which is part of Ragn-Sells, enables valuable resources to be utilised, at the same time as the hazardous fly ash can be dealt with safely. The salts can be used as road salt and in fertiliser production, among other things.
– Our technique converts fly ash from a waste problem to a resource. We can thus stop sending environmental liabilities onward to future generations and instead derive benefit from the materials that we already have, says Mikael Hedström, head of Ragn-Sells Business Area Treatment & Detox in Sweden.
Every year energy is recovered from almost seven million tonnes of waste in Sweden through incineration and production of district heating and electricity. Fly ash, a hazardous form of waste with high contents of heavy metals and other toxic elements, arises when the flue gases are purified after the incineration process. The ash is currently deposited as hazardous waste after treatment. The Ash2Salt method, a global patent developed by Ragn-Sells’ innovation company, EasyMining, instead detoxify it and enables the valuable salts in the ash to be utilised.
The Ash2Salt process extracts three salts which can be sold on the raw materials market: sodium chloride, potassium chloride and calcium chloride. Sodium chloride, or common salt, can be used as road salt or within the chemical industry. Potassium chloride is an important plant nutrient which is needed for fertiliser production, and calcium chloride can be used to combat ice and dust on roads.
– We are contributing to enabling a non-renewable resource like potassium to be returned to the fields and benefitting food production. At the same time, Sweden avoids exporting hazardous waste to landfill abroad, which reduces transportation and saves both the environment and money, says Mikael Hedström.
An element in the process is that the ash is washed before the desirable materials are extracted from the washing water. The washing makes the residual ash much less hazardous, which means that it can be deposited with less hazardous waste, reducing the need for landfill.
Production will take place at Ragn-Sells’ Högbytorp treatment plant in Bro outside Stockholm and the construction time is estimated at about 2 years.
Fly ash, a hazardous waste with high contents of heavy metals and chlorides among other things, is formed when flue gases are purified in connection with waste incineration. The Ash2Salt process washes the fly ash and three commercial salts are extracted from the wash liquid: sodium chloride, potassium chloride and calcium chloride. It is simpler to deposit the fly ash after it has been washed.
Using the Ash2 Salt method instead of putting the residual ash in a landfill for hazardous waste delivers a number of benefits, commercial as well as environmental.