GOLD IN PROCESSES OF PYRITE FORMATION. PART 1. GOLD ACCUMULATION DURING PYRITE FORMATION

Abstract

On the basis of the multistage model of pyrite formation at low and elevated temperatures, three types of sediments were synthesized: hydrotroilite, dehydrated hydrotroilite, and pyrite. Their sorption capacity with respect to gold was investigated by the method of 195Au radioactive tracer. The investigations were carried out in a wide range of parameters, involving those typical of natural sedimentary and sedimentary-hydrothermal processes: T = 25-200°C, CAu = 10-12-10-3 g/ml, pH = 3-12.5, and a liquid-to-solid weight ratio of 100 and 10 000. It was found that the sorption capacity of initial hydrotroilite with respect to gold was 1-2 orders of magnitude higher than that of pyrite. It was supposed that fine-dispersed gold could be formed during the hydrotroilite to pyrite phase transition owing to the release of excess initially accumulated metal. We discussed the chemisorption nature of gold accumulation and the influence of OH- and HS- groups in sediments on the deposition of the metal.