Alkaline injection technology: Field demonstration

In December 2001, 2225 tonnes of fluidized bed combustion (FBC) ash were injected into an abandoned coal mine in eastern Oklahoma. Post-injection monitoring continued for 24 months, during which the mine system appeared to be reestablishing equilibrium with CO2 in the mine headspace. Alkalinity and pH gradually increased, and as of December 2003 were roughly 65 ppm and 7.3, respectively. Metal concentrations were still significantly lower than pre-injection levels, but iron and manganese concentrations had increased from non-detect levels shortly after injection to roughly 30 ppm and 1.25 ppm, respectively. Aluminum, nickel, and zinc were less than pre-injection concentrations and did not appear to be increasing (roughly