Heavy metal outputs from a cement kiln co-fired with hazardous waste fuels

摘要

Measured data from a kiln equilibration test are analyzed for heavy metal outputs from a cement kiln co-fired with hazardous waste fuels. Metal outputs from stack emissions, cement kiln dust and cement clinker are considered. Equations are derived for predicting all three metal outputs at any hazardous waste feed rate under steady state conditions. Through analysis of two steady state conditions, at the beginning and end of the equilibration test, essentially the same ratios of metal feed rates are found to be distributed to the kiln dust at either high or low metal feed rates. Applying the same distribution ratios in the derived equations, metal concentrations of wasted kiln dust are predicted when the kiln is not using hazardous waste fuels. Measured concentrations of arsenic, beryllium, cadmium, chromium, and lead in wasted kiln dust, at the highest intended hazardous waste feed rates to the kiln, are 68, 10, 72, 18, and 68 times those predicted for feed rates with no hazardous waste. In addition, the intermediate, non-steady state segment of the equilibration test is analyzed. If metals are assumed not to accumulate in the kiln, the intermediate metal concentrations in cement clinker are predicted to be substantially higher than those at the final steady state.