Determination of Mercury in Low-Grade Ores

Abstract

Two new rapid and accurate methods are presented for determining mercury in low-grade ores and tailings: (1) A combustion–atomic absorption technique is described wherein a small sample of finely pulverized ore is heated to about 700°C, and the vaporized Hg is detected by atomic absorption. This method is suitable for determining Hg in the 0.1–5.0 lb/ton range, and the precision is about 5% coefficient of variation; (2) an x-ray fluorescence method is described wherein the unweighed, finely ground sample is merely packed into a holder, and the Hg line-to-background ratio is obtained. The problem of matrix effects is avoided by preparing standards to simulate the type of ore being analyzed. The method is suitable for determining Hg over a wide concentration range, with a lower limit of about 0.1 lb/ton. The precision, based on the analysis of a 2.0 lb/ton Hg ore, is about 5% coefficient of variation. These two techniques are compared to the commonly used Whitton and Bureau of Mines methods.