Power plant fly ash—disposal and utilization

Murtha, M.J.; Burnet, G.; Harnby, N.

doi:10.1002/ep.670020313

Cited by 16 publications

(1 citation statement)

References 4 publications

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“…The optimal conditions included sintering at 1250−1300 °C for 20−30 min, using a Na 2 O:Al 2 O 3 ratio of 1.2−1.3:1 and a CaO:SiO 2 ratio of 1.8−1:1, and leaching at 60−70 °C for 20−30 min with 5% soda solution. , Leaching the sintered material with water gives a lower SiO 2 content than leaching with NaOH and Na 2 CO 3 . , The sodium aluminate solution obtained is processed with Ca(OH) 2 suspensions at atmosphere pressure to desilicate, reducing the SiO 2 :Al 2 O 3 ratio to less than 1:1000. Fly ash was sintered with limestone and soda to form Ca 2 SiO 4 , and about 90% of the Al 2 O 3 was recovered as NaAlO 2 . , No apparent difference in reactivity was found between the Ca contained in the fly ash and that in the added limestone . The Al 2 O 3 yield was increased, and the sintering temperature was decreased by adding 2−10 wt % of carbon and sulfur at a S:C ratio of 0.5−1.5:1 and heating at 1100−1300 °C.…”

Section: Alkaline Processing Of Coal Ashmentioning

confidence: 99%

Technology for Chemical−Metallurgical Coal Ash Utilization

Rayzman

Shcherban

Dworkin³

1997

Energy Fuels

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Coal is a major contributor to power and heat generation in the United States. According to economic forecasts coal mining and consumption as fuel will increase through 2010. Simultaneously, deposits of ash from coal combustion are expected to accumulate extensively. Today, about quarter of coal combustion solid waste is used for cement and concrete production. Many millions of tons of aluminum and silicon contained in the coal wastes are annually lost in landfills. Use of coal ash as a raw material for production of chemicals and construction materials can significantly fulfill the U.S. need for these commodities while at the same time decrease dusty pollution. A fairly large number of processes for recovering alumina and byproducts from coal ash have been proposed and developed. These processes are classified by methods of ash decomposition into sintering and hydrothermal technologies and by extractant type into alkaline and acidic groups. On the basis of the available calculations, preference should be given to a combined process including the alkaline pre-extraction of silicon followed by lime−soda sintering of desilicated solid remainder. This review covers 98 papers, patents, and reports issued over the last 30 years. U.S. chemical and metallurgical industries are expected to resume growing through the end of the decade, and coal ash should be recognized as a practicable domestic raw material which can be utilized in a number of ways.

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