Stability limits of pulverized fuels, burned with the support of natural gas in quarl burners with swirling secondary air, are quantified. The potential heat release of the solid fuels was up to about 14 kW while the gas support was reduced, typically to less than about 12 kW, to find the extinction limits as a function of the swirl number, quarl length, secondary average axial velocity, downstream confinement and for Welsh anthracite, English bituminous coal and Greek lignite (the latter with 12% moisture). In unconfined operation, attached and lifted flames were produced at swirl numbers between 0.3 and 0.6, depending on the quarl length and the air velocity. The bituminous coal provided the broadest stability limits: dried lignite gave comparable lean stability limits but also introduced rich stability limits as the solid feed rate was increased. In confined operation, common rich stability limits were found for attached flames of all coal types: the lean limits were also common for swirl numbers less than than about 0.7. As lean extinction of confined bituminous-fired flames was approached, attached flames were followed by extensive lifted regions. As burner confinement increased, attached flames were observed, for all coal types, at lower values of swirl numbers.