Liming Characteristics of a Dry Flue Gas Desulfurization Byproduct.

Utilization of coal combustion byproducts (CCBs), which are rich in calcium and magnesium, as a liming material in agriculture can reduce the amount of CCBs requiring disposal in landfills and storage lagoons. The purpose of this experiment was to compare the liming characteristics and liming potential of a mixed CCB (MCCB) with those of lime (CaCO₃) and fly ash. MCCB, fly ash, and reagent-grade CaCO₃ were incubated at soil rates equivalent to 0.5x, 1x, and 2x the SMP liming requirement of an acidic Udult sub-soil (pH 4.32) for 40 d, with pH being measured every 5 d. The total neutralizing value (TNV), degree of fineness, and the effective neutralizing value (ENV) were determined for all three liming materials. The pH of the soil in all three treatments increased over the 40-d incubation period. The pH after 40 d for the 1x liming requirement treatments was 7.02, 6.70, and 6.96 for the lime, fly ash, and MCCB, respectively. Soil incubated with CaCO₃ had the greatest increase in pH in the first 5 d, which was attributed to the fine particle size (i.e., 100% passing through a 100-mesh sieve) of this material. The similar performance of MCCB and lime demonstrates the ability of MCCB to ameliorate soil acidity. Use of CCBs in agriculture can reduce the economic and environmental concerns of long term CCB storage by decreasing the amount of material placed in landfills and storage lagoons.