Coal Combustion Residuals: From Waste Product to Useful Commodity

September 1, 2022

The majority of the electricity powering your home or office right this very moment may have gotten its start in the ground many, many years ago as decomposing organic waste that today is burned as coal. In the simplest of terms, coal is burned to heat water to produce steam to spin turbines to generate electricity. So, what becomes of what is left of the coal after it’s burned?

• • •

Coal Combustion Residuals (CCR) are produced in the creation of electricity in coal-fired power plants and are the remnants from the burnt coal (i.e., ash) that are collected from the flue gases and boilers, as well as other by-products produced as part of air quality emission control systems. The primary CCR materials include:
Fly Ash, a very fine, powdery material composed mostly of silica collected prior to the flue gases emitting from the smoke stacks.
Bottom Ash, a coarse, angular ash particle that is too large to be carried up into the smoke stacks so it forms in the bottom of the coal furnace.
Flue Gas Desulfurization Material, a material leftover from the process of reducing sulfur dioxide emissions from a coal-fired boiler that can be a wet sludge consisting of calcium sulfite or calcium sulfate or a dry powered material that is a mixture of sulfites and sulfates.

CCR is one of the largest types of industrial waste generated in the United States. According to the American Coal Ash Association’s Coal Combustion Product Production & Use Survey Report, nearly 79 million tons of coal ash were generated in 2019.

New team member brings expertise

One of CEC’s newest team members is an expert in the management of CCR. Bill Almes, P.E., is a Senior Principal in our Waste Management practice. He brings more than 30 years of experience as a consulting engineer specializing in civil, environmental, and geotechnical engineering.

His experience includes work in the Mining, Power, and Solid Waste industries. The majority of his project experience has been focused on municipal solid waste and industrial waste management facilities, renewable energy, CCR landfills and impoundments, and coal refuse disposal facilities. These projects required local, state, and federal environmental permitting, facility design, geo-environmental investigations, construction quality assurance, construction certification services, and environmental compliance.
Almes’s broad expertise in CCR reuse is especially valuable to clients.

For many years, CCR was simply disposed of in landfills and surface impoundments. Landmark failures in Tennessee and North Carolina accelerated change to disposal practices.

On Dec. 22, 2008, a failure of a dike used to contain coal ash occurred at the dewatering area of the Tennessee Valley Authority (TVA) Kingston Fossil plant in Roane County, Tenn. During the dike failure, approximately 5.4 million cubic yards (1.1 billion gallons) of coal ash slurry was released into Swan Pond Embayment and three adjacent sloughs, eventually spilling into the Emory and Clinch Rivers.

To assist the TVA Office of Inspector General (OIG) with technical aspects of the root cause analysis (RCA) report provided by others, Almes led a team of geotechnical experts to peer review the RCA findings and provide observations concerning ash management practices at TVA. The sole mission was to provide an independent review on behalf of the OIG and the U.S. Congress.
“We were tasked to make sure Congress knew the real reason [the failure] happened,” says CEC Pittsburgh’s Almes says.

On Feb. 2, 2014, a release of coal ash occurred at the Dan River Steam Station in Rockingham County, N.C. The estimated quantity of ash released was between 50,000 and 82,000 tons. Also, approximately 27 million gallons of ash pond wastewater was released. The released ash and water was discharged to the Dan River.

These events ushered in changes to U.S. EPA regulations to reduce the chances of future failures and releases.
Almes says many power companies have increased their efforts to beneficially reuse the CCR materials in order to reduce the volume of materials that require permanent disposal and are moving away from disposing of CCR in impoundments by placing the CCR materials in new lined landfills — monofills — which accept only the CCR and meet the latest regulatory requirements.

Typically, monofills are superior to unlined CCR landfills and impoundments since they are permitted (approved by state regulatory agencies) disposal facilities constructed with state-of-the-art composite liner and cover systems and leachate collection systems. Essentially, dedicated monofills are established to provide a safe long-term disposal means to protect the environment.

These are usually located adjacent to or very near the power plants, reducing the transportation costs and minimizing safety concerns as heavy truck traffic is reduced in roads. Some are sending the CCR to existing lined landfills, where it is separated from the other wastes.

“The landfills that accept CCR are mostly owned by the power companies and other private waste disposal companies. The design, permitting, and approval process always takes time,” he says.

CEC guides power companies through regulatory changes

That’s where the expertise of CEC comes into play, guiding these power companies through the maze of regulatory changes when it comes to dealing with the CCR materials.

“We keep up with the frequently changing federal rules and decisions, as well as those of the states, which can have their own regulatory requirements, adding another layer of compliance,” Almes says.

While getting these waste products safely disposed is of the utmost importance, the beneficial reuse of CCR offers an exciting second life for CCR that has been previously placed in impoundments and landfills.

The power company (and their subcontractors) can process, separate, and sell the CCR that is currently being produced or has been disposed of for beneficial use.

While millions of tons of buried CCR are being removed from disposal areas and transported to approved landfills, some of it is being recovered for use by the cement/concrete industry and for other beneficial uses.

This is The SEFA Group’s Winyah STAR beneficiation plant in Georgetown, S.C. It’s one of the STAR facilities transforming Coal Combustion Residuals (CCR) into products used in the concrete industry.
Photo used with permission of The SEFA Group.

The SEFA Group (SEFA) is a company that repurposes the ash. STAR® (Staged Turbulent Air Reactor) Technology is a patented thermal beneficiation process to transform harvested coal ash from surface impoundments or landfills into a high-quality, sustainable product for the concrete industry.

The process removes contaminants and provides a reliable raw material that meets or exceeds all specifications for additives in concrete.

The process is self-sustaining and exothermic, meaning no external fuel source is required for continuous treatment.

Jimmy Knowles, SEFA Vice President Government & Environmental Relations, says there is not enough surplus ash being produced in power plants now to meet the existing demand. “Ash is a desired commodity. It doesn’t matter if the ash is five months old or 50 years old. The embodied energy is in the ash.”

SEFA has recycled more than 25 million tons of fly ash that would have otherwise gone into landfills or ponds and was the first company in the world reclaiming and recycling coal ash from ponds for concrete on a commercial scale. The company operates five STAR plants in the Carolinas.

“We take previously disposed, legacy ash and make it suitable for use,” Knowles says. The material is there for the taking in disposal ponds and monofills; however, additional state and federal permitting is required before the excavation can begin. “We’d like to think of the coal ash disposal sites as ‘storage stockpiles’ and shift the focus to beneficial use.”

Outside-of-the-box thinking

“That’s why we love working with firms like CEC who help us think outside the box,” Knowles adds. “We are looking to create a paradigm of beneficial use from the get go, rather than disposing of it and then having to dig it back up.”

Workers smooth concrete during the reconstruction of Pennsylvania’s Highway 219. The concrete contains CCR treated in one of SEFA’s STAR plants.
Photo used with permission of The SEFA Group.

“The use of fly ash in Portland cement concrete has many benefits and improves concrete performance and the strength and durability of hardened concrete. Fly ash use is also cost-effective. When it is added to concrete, the amount of Portland cement may be reduced,” Almes says. The chemical properties of all fly ash varies widely and some materials, when mixed with water, makes the concrete stronger.

Another benefit of some CCR materials is the recovery of Rare Earth Elements (REEs), which are comprised of only 17 elements from the periodic table.

REEs are used extensively in the manufacture of microchips, which are an essential part of many sectors of the U.S. economy including health care, transportation, power generation, petroleum refining, and consumer electronics (everything from cars and trucks to cellular phones and TVs). Because of this critical role, interest and research into the recovery of REEs from coal, coal refuse, and CCRs has recently increased. These minerals can be isolated, processed, and sold to the chip manufacturing industry, here and abroad, he adds. “Our federal and state governments are funding ongoing research for this process.”

“We want to be part of the process … to be on the leading edge of extracting those elements,” Almes says.
“It’s a cool takeaway. We are letting people know CCR can be a good thing.”

About the Author


Jonna Miller

Jonna Miller is a Marketing Manager with CEC. She has more than 30 years of experience in writing, editing, and photography.

Want more content like this?

Subscribe

Post a Comment


Your email address will not be published.