Digesting high-aluminum coal fly ash with concentrated sulfuric acid at high temperatures

In this study, fly ash was modified by concentrated sulfuric acid, and it was used in the treatment of phosphorus-containing wastewater, then we have investigated the impact of the different modification conditions on the adsorption, the results show that: in the condition of 5g of fly ash by adding 0.15 mL of concentrated sulfuric acid and 3 mL water, 1.5 h of drying time, the temperature of 100°C, the effect of removaling Phosphorus is the best,and the adsorption efficiency can reach 94.6%. The adsorption rate was fast, and the adsorption can react in condition of wide pH value.

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Dewaterability of Excess Activated Sludge with Fly Ash Conditioning

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.726-731.2651 ◽

2013 ◽

Vol 726-731 ◽

pp. 2651-2654

Author(s):

Chang Nian Wu ◽

Wei Hua Li ◽

Qi Ling ◽

Li Wang ◽

Fa Kang Pan ◽

...

Keyword(s):

Sulfuric Acid ◽

Fly Ash ◽

Activated Sludge ◽

Extracellular Polymeric Substance ◽

Specific Resistance ◽

Coal Fly Ash ◽

Polymeric Substance ◽

Conditioning Process ◽

Sludge Dewaterability ◽

Sludge Conditioning

The coal fly ash (CFA)/coal fly ash modified by sulfuric acid (MCFA)-conditioned sludge dewaterability was investigated in this study. Specific resistance of filtration (SRF) was used to assess the sludge dewaterability. Extracellular polymeric substance (EPS) was determined in attempt to explain sludge conditioning process. The results showed that SRF of the sludge significantly decreased with coal fly ash addition, and the MCFA showed much stronger conditioning capacity than the raw coal fly ash. Under a MCFA dosage of 36g.L-1, the SRF of the sludge decreased from 1.18×1012 to 6.47×1010 m.kg1, and EPS concentration of the sludge decreased from 32.64 to 17.55mg.L-1. The sludge conditioning mechanisms with MCFA mainly included improving adsorption bridging and providing the water transmitting passages by skeleton builder.

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Effect of Coal Fly Ash as Additive on the Sulfur Retention of Coal Briquette

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.512-515.1583 ◽

2012 ◽

Vol 512-515 ◽

pp. 1583-1588

Author(s):

Yan Xia Guo ◽

Yu Ting Li ◽

Fang Qin Cheng ◽

Feng Ling Yang

Keyword(s):

Fly Ash ◽

High Temperatures ◽

Coal Combustion ◽

Coal Fly Ash ◽

Clean Coal ◽

Sulfur Containing ◽

Sulfur In Coal

Clean coal briquette is one of the most effective techniques to remove SO2 from coal combustion by using sulfur-retention agent to retain sulfur in coal residuals. Ca(OH)2 has been proved to be an effective sulfur-retention agent. CaSO4 as the primary sulfur-containing product, however, is thermal unstable at high temperatures. It has been reported that SiO2, Al2O3, Fe2O3 etc. are excellent sulfur retention additives, those are abundant in coal fly ash. In this study coal fly ash was used to the additive to improve the sulfur retention of coal briquette. The results showed that the addition of coal fly ash can improve the sulfur retention. The modified coal fly ash obtained by calcinations assisted with Ca(OH)2 can improve the sulfur retention more noticeable. The SEM and XRD results further indicated that coal fly ash promoted the formation of the sulfur-containing products such as Ca-Si-S-O compounds with high thermally stability.

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