Economics of Disposal of Lime/Limestone Scrubbing Wastes: Surface Mine Disposal and Dravo Landfill Processes

摘要

The report gives results of economic evaluations of flyash and limestone scrubbing waste disposal in a surface mine and in a landfill after treatment with a Dravo Lime Co. chemical additive. For the base case (new 500 MW midwestern plant burning 3.5% S, 16% ash, 10,500 Btu/lb coal), capital investment for the mine disposal process is 16.0 $/kW and annual revenue requirements are 0.98 mill/kWh, compared to 20.0 $/kW and 1.44 mills/kWh for the landfill process, excluding dry flyash collection costs of 19.2 $/kW and 0.56 mill/kWh. A moderate cost reduction is obtained for mine disposal, compared to landfill disposal of the same waste, by eliminating disposal land requirements and reducing earthmoving equipment requirements. Purchasing and handling the chemical additive for the landfill process account for most of the cost differences between the two processes. Power plant size, coal sulfur and ash contents, and distance to the disposal site have major cost effects for both processes. Modular cost breakdowns show purchase and handling of fixatives, thickening, ESP units, and disposal labor to be major cost elements.