Addressing Coal Ash Environmental Challenges and Growing Federal and State Regulations for Ash Pond Closures With Thermal Process Fly Ash Beneficiation Technology
- Mar 30, 2020 7:49 pm GMT
Today there are over 1,000 ash ponds and landfills in the U.S. requiring EPA-mandated closures or remediation while growing federal and state regulations are placing additional pressure on utilities. After nearly a decade of slowing or reduced output, electricity use from coal-fired power plants is expected to level off but remain as an important energy source so utilities must find economic and sustainable solutions to control ash pond closure costs.
At the same time, the demand for coal combustion products (CCPs) for infrastructure projects is increasing. According to the American Coal Ash Association (ACAA), over 60% of all CCPs produced in 2017 were beneficially used in the production of concrete and this percentage is expected to increase. This provides an opportunity for utilities to meet the needs of concrete producers with more economical cost control of pond closures. According to the ACAA, there is an estimated 1.5 billion tons of legacy CCRs stored in surface impoundments or landfills. If these stored CCRs could be processed to become marketable CCPs, it would help to alleviate current supply issues. As current generation continues to decline, these stored CCRs can be mined as a resource to satisfy the market need. The emergence of new advanced technology to recapture and refine stored CCRs has the potential to transform the market.
In the U.S. market, CCP resource availability is linked to three potential sources: 1) current coal-fired plant generation, 2) reclamation of CCRs stored in landfills, ash ponds or surface impoundments, and 3) imported CCRs. The ability of the first two sources to meet rising demand is being heavily affected by EPA federal and state regulations, and other significant factors.
The shortage of fly ash is partly due the fact that not all fly ash immediately meets ASTM and state specifications for beneficial use and either needs to be processed to remove the extra carbon or stored in landfills. Utilities have been searching for an effective solution that allow them to meet federal and state mandates for ash pond closures and help offset some of these costs through the sale of beneficially used CCPs. In this changing utility environment, one of the best ways to reduce the impact of having to navigate the strict guidelines governing CCR waste disposal and storage is to adopt technology that raises the quality of a greater percentage of CCRs to reach the standards required for beneficial use.
Fly ash with an LOI (Loss on Ignition) above 6% does not meet ASTM or state specifications. In addition, fly ash with Ammonia content above 100 ppm is also commonly avoided by concrete producers while fly ash with mercury concentrations above 200 ppb is not used by cement kilns as a raw material, according to the EPA’s NESHAP National Emission Standards for Hazardous Air Pollutants (NESHAP).
With these broad usage limitations, utilities are often relegated to storing the unsellable fly ash in landfills which increases their costs. Concrete producers face an ongoing challenge of consistently sourcing the quality and supply of usable fly ash they need, while utilities look for ways to reduce landfill material and increase fly ash productivity while making their operations more sustainable. Until now, technology solutions for the beneficiation of high-carbon/unsellable fly ash have been massive and immobile, expensive to operate, with an extensive timeframe for setup.
To address this industry-wide problem, a new proprietary fly ash thermal beneficiation technology has been developed that improves the quality of fly ash produced at electric utilities and increases supply of marketable fly ash to concrete producers nationwide, thus lowering the costs of mandated pond closures at the utility level.
- The newest fly ash beneficiation technology in the market allows for beneficiation of both wet and dry fly ash, reduces loss on ignition (LOI), ammonia, activated carbon, and moisture in fly ash at significantly lower cost profile than other technologies. It takes ash that is unusable and converts it to a consistent high-quality fly ash that meets industry specifications meaning that it can be used as a replacement material in the production of concrete. The new system can be installed at both operating and non-operating power plants to process current ash production or legacy ash stored in ponds and landfills. What is most impressive is its ability to deliver all of these benefits at a significantly lower cost profile than other ash beneficiation technologies, combined with an efficient footprint.
Test results show consistent LOI and Ammonia reduction over a wide range of fly ash inputs as well as the capture of mercury from the exhaust air stream.
The new ash beneficiation technology serves a clear need for cost-effective, efficient and sustainable solutions that can be scaled up or down at the utility site(s) based on the beneficiation needs at a particular pond or site to beneficiate out-of-spec fly ash, increase supply of high-quality ash to the market and provide reduced costs to utilities who are under pressure to close ash ponds
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