Coal bottom ash

Leaching of trace metals from CCB materials is of potential concern for contamination of natural water supplies. For example, Groenewold etal. (1985) found elevated levels of As, Cr, Mo, Pb, and Se in groundwater below a lignite fly ash landfill in North Dakota, and Shende et al. (1994) found stockpiled coal bottom ash contributed leachable metals to adjoining rivers. However, it also has been observed that weathered CCBs have the ability to retain many metals (Janssen-Jurkovicova et al. 1994 Steenari et al. 1999). 

The bulk of the samples for this study came from TVA s Allen Steam Plant at Memphis, Tenn. The sampling points (Figure 4) included inlet air, coal, bottom ash, precipitator inlet, and outlet at the 268-ft stack level. During the 2-week sampling period the unit was operated under steady state conditions at 240 MW (12) with a uniform coal supply so that a mass balance might be established for a number of elements. All the coal from southern Illinois was washed and crushed so that 90% was less than 4 mesh. Nominal coal analysis indicated the following composition 9.5% moisture, 34% volatiles, 43% fixed carbon, 13% ash, and 3.4% sulfur. 

DOE ash waste Activated carbon, 5 Vermiculite, 20 Class F fly ash, 40 Coal bottom ash, 33 HgClz added such that Hg level was 0.5... 

Goodarzi Fand Huggins FE (2001) Monitoring the species of arsenic, chromium and nickel in milled coal, bottom ash and fly ask from a pulverized coal-flred power plant in western Canada. J Environ Monit 3 1-6. 

Coal bottom ash/ boiler slag BA/BS 53.5 million t (59.4 million T) 15 Reclaimed asphalt pavement RAP NR... 

Coal bottom ash (BA) and boiler slag (BS) are the coarse, granular, incombustible by-products that are collected from the bottom of furnaces that burn coal for the generation of steam, the production of electric power, or both. The majority of these coal by-products are produced at coal-foed electric utiUty generating stations, although considerable BA and/or BS are also produced from many smaller industrial or institutional coal-fired boilers and from coal-burning independent power production facilities [50-57]. The type of by-product (BA or BS) produced depends on the type of finnace used to burn the coal. The main differences between coal bottom ash and boiler slag are summarized in Table 3. 

Stabilized base - aggregate Coal bottom ash Coal boiler slag... 

Element Symbol Coal Bottom ash Precipitated ash Bag ash Stack ash... 

Comprehensive operation data from the HTW pilot unit in Frechen, Germany, can be found in the final technical report [137]. The applied fuel is Rhenish Lignite, which is dried to a moderate water content of 12wt%(ar). Table 6.16 shows the average properties for the feed coal, bottom ash, and fly ash representing the solid input and output streams of the system. 

Canpolat et al. [33] have suggested the usage of zeolite, coal bottom ash and fly ash as replacement materials for production of the cement. It has been opined that the inclusion of zeolites, up to 15 %, results in an increase in the compressive strength of the cement, at early ages, whereas a decrease in compressive strength is observed when zeolites are used in combination with the fly ash. However, the setting time is found to decrease due to the replacement of clinker by the zeolite. This has been attributed to presence of adsorbed water (the excess water remained unused after the hydration process in the cement) on the zeolite surface. 

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