Multitechnique multielemental analysis of coal and fly ash

Abstract

The coal sample is first ashed with high temperature ashing or with RF plasma low temperature ashing. The coal ash or fly ash can be analyzed for major ash elements by fusing with lithium tetraborate in an automatic fusion device, the Claisse Fluxer. The ash samples are also dissolved in a Parr bomb in a mixture of aqua regia and HF. Subsequently, the solutions are analyzed for eight major (AI, Ca, Fe, K, Mg, Na, Si, and Ti) and 20 trace elements (As, B, Ba, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Sr, U, V, and Zn) by inductively coupled plasma emission spectroscopy. Mercury in coal and fly ash is determined on a separate aliquot by the cold vapor atomic absorption technique. Fluorine and chlorine in the samples are determined by fusing with Na,CO, and Eschka mixture, respectively, and then measuring the two ions In solution with specific ion electrodes. Oxygen in the samples can be determined rapidly and nondestructively by 14-MeV neutron activation analysis. These methods have been tested by analyzing several NBS coal and fly ash standards with good accuracy and reproducibility.Oil and gas a t present supply three-fourths of the energy used in the United States. In spite of the increasing conservation measures taken, our import of these materials is steadily on the rise. However, the supply of these hydrocarbon fuels worldwide is expected to decline in the foreseeable future.T h e only practical alternative energy supplies a t present are nuclear energy and coal.T h e world reserves of coal far exceed those of any other fossil fuel and are sufficient to support a massive increase in consumption well into the future. It is estimated that the United States has 1.7 trillion tons of coal ( I ) . Despite these massive reserves, however, the amount of coal used in this country has remained almost constant a t about 600 million tons per year for the past few years ( 2 ) . One of the chief reasons for this lack of coal utilization is the environmental concern as to how much increase in atmospheric pollution will take place by burning increased amounts of coal.Coal is a fairly "dirty" fuel and contains large amounts of many inorganic elements. At the same time, there are wide variations in the trace elements content of coal seams even within a single mine. Hence, it is important to have reliable analytical methods which can monitor the inorganic constituents a t various stages of coal production and utilization. Since as many elements as possible need to be monitored in the coal products, it is desirable to have multielement rather than single element techniques.The need for the standardization of the analytical methodology and availability of analytical standards was illustrated by the U S . Environmental Protection Agency's round robin analysis of four fuel matrices for 28 elements in nine laboratories (3). Same samples of coal, fly ash, fuel oil, and gasoline were analyzed for 28 elements in nine laboratories by a variety of analytical techniques -neutron activation analysis, atomic absorption spectrophoto...

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