A coal ash beneficiation plant at the Santee Cooper Winyah Generation Station in Georgetown, SC, has entered commercial operation, joining two other Sefa Group sites equipped with the proprietary Staged Turbulent Air Reactor (STAR) processing technology.
The stand-alone Winyah facility adapts to various fuels and raw feeds exhibiting a range of LOI (loss on ignition) carbon content, and will process material from inactive storage ponds plus dry ash from the station’s active coal-fired units. It is capable of 500,000 tons’ annual output, about 70 percent of which will meet ASTM C618 Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete guidelines.
Due to prolonged water exposure, Sefa notes, ponded coal ash undergoes chemical weathering, which reduces its strength-developing characteristics in concrete. Hence, simply drying and grading such material does not yield specification-level, finished ash. STAR processing restores concrete strength-imparting properties in pond ash, a strong value proposition for utilities aiming to lower or eliminate long-term storage or disposal liabilities.
Santee Cooper officials chose the Sefa process as part of their ash pond closure strategy. “[We] aggressively pursued innovative opportunities to empty ponds at Winyah, Jefferies and Grainger stations through recycling, or beneficially reusing, the ash,” says Lonnie Carter, the state-owned utility’s chief executive officer.
With 15-plus years in thermal beneficiation, yielding more than 5 million tons of processed ash, SEFA Group is promoting the STAR technology as a unique, proven solution for pond ash management and new source of ASTM C618-grade fly ash.