Exhausting Alternatives

 

There is an important distinction in the by-products of the two types of scrubbers a coal burning power plant can install.  The by-products of a wet scrubber are easily utilized in the current Coal Combustion By-Products (CCP) market within ready-mix concrete, Portland cement, wall board and other road construction material.  The research on utilization of byproducts from dry scrubbers, also referred to as Spray Dry Absorbers (SDA), is only recently being investigated and has shown some positive yet, not completely understood results.  With that said, here are the current and potential uses for SDA material:

 

Concrete

In 2005, about 14,000 tons (1% of CCPs in United States) of SDA material was used for the production of concrete and concrete products.  Because of the expansive nature of dry scrubber CCPs, this area of utilization is still being investigated.

 

Masonry

There have been good results in utilizing SDA material for concrete blocks however the material may need to be conditioned prior to use as a means to produce a marketable product.

 

Flowable Fill

Because of certain properties (moisture density, compressive strength and permeability) SDA materials could be well utilized for flowable fill material and SDA material can be an economical alternative to conventional materials.  More research needs to be done to assess the long-term strength, stress-strain behavior, freeze-thaw properties, swell potential and corrosiveness.

 

Synthetic Aggregate

Much like using SDA material in masonry, it can be used as a synthetic aggregate and has potential use in the manufacturing of bricks, concrete blocks, and other compacted shapes.

 

Mining Fill

SDA material has been used commercially as mine fill and is capable of neutralizing soil acidity and aiding in the re-establishment of vegetative cover.  However, too much SDA material has caused excessively high pH and cementation.  

 

Agricultural

According to a study by the Electric Power Research Institute, “the potential for SDA material to be used as a liming agent or for soil amendment has received mixed results depending on the pH of the soil, crops planted, amount of SDA material used and whether the SDA material was blended with any other material”.

 

Other Alternatives

Other applications of SDA material that are currently under exploration include: