The beneficiation of Martin Lake Texas lignite

Abstract

Martin Lake lignite from Wilcox County, Texas, yields a moderate level of ash (11.3%) on combustion and has 13% inertinite macerals. These both act as diluents during liquefaction processing. A beneficiation process comprised of size selection, aqueous sulphur dioxide treatment and sink/float separation using heavy media was evaluated and shown to be effective. With laboratory scale equipment, the combined process gave a lignite product with 2.5% ash. A lignite recovery of 82% was achieved. In a commercial process the remainder could be used as plant fuel. Petrographic analyses of the various treated fractions were performed. The huminite (vitrinite) macerals were concentrated in the low gravity fractions whereas the inertinite was concentrated in the high gravity fractions. Owing to the association of the liptinite macerals with minerals, their distribution was bimodal with the highest contents occurring in both the high and low gravity cuts.