97/01001 The utilization of coal pond fines as feedstock for coal-water slurry fuels

Abstract

It has been reported that coal slurry fuels were first introduced in the 1870`s in the form of coal-oil mixtures. It was the fuel oil supply shortages and price increases of the 1970`s that created an economic incentive for the development of fuel oil-replacement fuels. The envisioned applications of coal-water slurry fuels (CWSFs) through the 1980`s were essentially the same as those for fuel oil: industrial and utility steam boilers, blast furnaces, process kilns, and diesel engines. The concept involved substituting CWSF for fuel oil with minimal retrofitting of the existing oil-fired system. Such fuels require fairly stringent quality restriction: low ash, high solids loading and low viscosity, which resulted in significant problems with stability. In many cases, the use of additives was required, thereby increasing the cost of the fuel. When oil prices fell during the 1980`s, CWSFs lost economic viability due to the cost of production and the capital intensive modifications required to retrofit oil-designed boilers. One approach to lowering the cost of CWSFs is to use coal refuse as the feedstock and to cofire the CWSF with pulverized coal. The utilization of coal fines can account for up to 20% of the total coal cleaned in amore » preparation plant. The use of fines, therefore, has the potential to reduce the amount of coal discarded and to lower overall fuel costs. Problems associated with the surface disposal of coal waste include: the nonproductive use of land, the loss of aestheitc value, the danger of slides, dam failure, significant permitting costs, and water pollution. It is estimated that 2 billion tons of coal refuse are contained in impoundments in the U.S. Over 75% of these fines are in states east of the Mississippi River. The current annual production of coal fines at preparation facilities exceeds 50 million tons. This does not include anthracite fines, which could account for additional 100 million tons in eastern Pennsylvania.« less