Advancing flue gas treatment
The classic treatment of land filling involves the method of stabilisation followed by solidification. Stabilisation is required to decrease potential dangers of waste by turning the contaminants into a soluble form without necessarily changing their physical make-up. Solidification turns the waste into a solid with a firm binding structure by means of a chemical reaction. Using Mg-based sorbents is the new alternative for flue gas treatment. Significantly lower quantities of Mg-based agents are needed to neutrilise the same amount of pollutants as compared to Ca-based agents. Also, Mg-based sorbents are safer to use, less corrosive and more environmentally friendly. Furthermore, Mg-based products have the suitable pH value for the lowest solubility of heavy metals, which makes stabilisation easier. The most applied practice for flue gas treatment is using dry lime as a stabilising/solidifying reagent. The lime is used with the ash residue and forms a cement-like substance. However, recycling and reusing residues, including fly ashes, coal burning ashes, and APC residues, is another alternative. Combining APC residues with slurry MgO provides higher solubility but separation and purification still remain difficult. Because APC residues are considered hazardous waste landfill, the new method will have to prove healthy and it will take time to provide such results. If the advantages of magnesium oxide assist in reinforcing the competition between sorbing agent suppliers, the result may lead to an increase in the cost of calcium-based products. Magnesium oxide is a widespread product in Europe and its promotion will open new opportunities for its application. This will mean cleaner and more efficient waste management in the gas treatment industry.
