Heavy Metals

Heavy metals released by the combustion process as particulate matter or gaseous form can accumulate in the food chain, in the human and animal tissues.

Using the SOLVAir® solution, these pollutants are easily controlled by adding to the sodium bicarbonate BICAR® an adsorbent like activated coal or lignite coke.

Mercury is a toxic, persistent pollutant that accumulates in the food chain, like other heavy metals. It is generated, together with other heavy metals (Pb, Zn, As, Cd …) in fossil fuel-fired power plants, waste combustion and industrial processes. 

The SOLVAir® Solution: dry sorbent injection of sodium bicarbonate for flue gas cleaning

When used as a dry sorbent injected upstream from a bag filter, the sodium bicarbonate BICAR® reacts with SO3, which competes with Hg for active sites on the surface of activated carbon and fly ash particles. Furthermore, after the thermal decomposition, the sorbent becomes porous and has high specific surface area (~ 10 m2/g) which enables some adsorption of mercury as well. 

Therefore, the sodium bicarbonate BICAR® is able to remove 20-70% mercury when used alone and over 99% when used in combination with activated carbon (or lignite coke) on a bag filter.
 
So activated carbon and the lignite coke permit the levels of removal required by the most stringent waste incineration emission limits for all flue gas temperatures below 220°C. At higher temperatures, mercury removal becomes less efficient. As other heavy metals are less volatile in comparison with mercury, their removal efficiency is even better. 

ELV Hg:< 0.05 mg/Nm3, dry, 11% O2
ELV Cd + Tl:< 0.05 mg/Nm3, dry, 11% O2
ELV other heavy metals:< 0.5 mg/Nm3, dry, 11% O2