Applicability of the Reichert spiral for cleaning bituminous and lignitic coals: a pilot scale study

The Reichert spiral which has been particularly developed for the beneficiation of fine coal in the size range of -3 + 0.1 mm is considered as an alternative for fine coal jig, cyclone, and flotation. A systematic study has been carried out to test the separation efficiency of the Reichert spiral on a bituminous coal and lignite. The effect of particle size, pulp density, the presence of fines, and the number of cleaning stages has been studied as a function of separation density. It is shown that cleaning of coal at densities below 1.5 g/cm³ seems inefficient under optimum operating conditions. The Reichert spiral is capable of cleaning the bituminous coal more efficiently than lignite in view of the smaller number of cleaning stages. Lignite, however, requires lower separation densities compared to the bituminous coal. The effect of various parameters on spiral performance is delineated with the aim of developing an optimum strategy for cleaning low quality coals.